deliverable d5.1: test protocol definitions filedeliverable d5.1: test protocol definitions...

Deliverable D5.1: Test protocol definitions

FluMaBack Fluid Management component

improvement for Back up fuel cell systems

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Grant Agreement number: 301782 Project acronym: FluMaBack Project title: Fluid Management component

improvement for Back up fuel cell systems Application area: Stationary power production and CHP Topic: SP1-JTI-FCH.2011.3.3: Component

Improvement for stationary power applications

Research and technological development Funding Scheme: Collaborative Project Project start: 01/07/2012 Project duration: 36 months

Date of latest version of Annex I against which the assessment will be made:

30/03/2012

Due date of deliverable: 30/06/2013 (M11) Lead beneficiary: EP Prepared by: EP, ElectroPS, Domel, Tubiflex, Onda, JRC Report submitted: 02/08/2013

Project co-funded by the Fuel Cells and Hydrogen Joint Undertaking within the Seventh Framework

Programme

Dissemination Level

PU Public X

PP Restricted to other programme participants (including the FCH JU)

RE Restricted to a group specified by the consortium (including the FCH JU)

CO Confidential, only for members of the consortium (including the FCH JU)

EU restricted Classified with the mention of the classification level restricted "EU

Restricted"

EU confidential Classified with the mention of the classification level confidential " EU

Confidential"

EU secret Classified with the mention of the classification level secret "EU Secret "




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DOCUMENT REVISIONS

Version Date Prepared / changed by

Comments

0.1 02/05/2013 EP First draft

0.2 17/05/2013 Domel revision

0.3 17/06/2013 JRC revision

0.4 02/08/2013 EP Last draft




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Contents List of Tables ............................................................................................................... 4 List of Figures .............................................................................................................. 5 List of abbreviations ..................................................................................................... 6 1. INTRODUCTION .................................................................................................... 7 2. TEST PROTOCOL ................................................................................................... 9 2.1 Air blower and hydrogen pump (first releases) test protocol ............................. 11 2.1.1 Air blower fine characterization tests ......................................................... 11 2.1.2 H2 recirculation pump fine characterization tests ...................................... 14

2.2 Air blower and hydrogen pump life/ageing test protocol ................................... 18 2.2.1 Recirculation pump life/ageing test ........................................................... 18 2.2.2 Air blower life/ageing test ......................................................................... 22

2.3 Humidifiers test protocol ................................................................................. 25 2.3.1 Humidifier fine characterization test .......................................................... 26 2.3.2 Humidifier life/ageing test ........................................................................ 27

2.4 Heat exchanger test protocol .......................................................................... 28 2.4.1 Heat exchanger fine characterization tests ................................................. 28

2.5 Test procedures ............................................................................................. 31 2.5.1 Air blower test procedures ........................................................................ 31 2.5.2 H2 pump test procedures ......................................................................... 31 2.5.3 Humidifier test procedures ........................................................................ 32

2.6 Prototype of FC system’s test protocol ............................................................. 33 2.6.1 Fuel cell System layout ............................................................................. 35 2.6.2 General test structure .............................................................................. 36 2.6.3 First and second release test at EP_ Base test procedure ........................... 39 2.6.4 Second FC system Release Test at JRC_climatic chamber tests ................... 42 2.6.5 Second FC system Release Test at EPS_lifelong tests ................................. 44

3. DATA ANALYSIS & RESULTS INTERPRETATION .................................................... 46 3.1 Performance evaluation criteria for the individual components and FC system ... 46 3.1.1 Performance evaluation of the air blower .................................................. 46 3.1.2 Performance evaluation of the H2 pump .................................................... 47 3.1.3 Performance evaluation of the Humidifier .................................................. 47 3.1.3 Performance evaluation of the FC system .................................................. 54

3.2 Lifetime validation & aging model for individual component and FC system ....... 55 3.2.1 Lifetime validation model for air blower and H2 pump ................................ 55




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List of Tables TABLE 1: BLOWER PERFORMANCE SPECIFICATION FOR 3 KW AND 6 KW FC BACK-UP POWER SYSTEM ............ 11 TABLE 2: AIR BLOWER TEST BENCH COMPONENTS AND RANGES............................................................ 12 TABLE 3: H2 PUMP PERFORMANCE SPECIFICATION ............................................................................ 14 TABLE 4: HYDROGEN PUMP TEST BENCH COMPONENTS AND RANGES ...................................................... 16 TABLE 5: HYDROGEN PUMP BEARING CHARACTERISTICS (DOMEL DATA) ................................................. 19 TABLE 6: DUTY CYCLE RATING LIFE .............................................................................................. 20 TABLE 7: BLOWER BEARINGS CHARACTERISTICS (DOMEL DATA) ........................................................... 22 TABLE 8: DUTY CYCLE RATING LIFE .............................................................................................. 23 TABLE 9: HUMIDIFIER PERFORMANCE SPECIFICATION ........................................................................ 25 TABLE 10: PERFORMANCE REQUIREMENTS FOR THE H2/AIR HEAT EXCHANGER TO BE DEVELOPED FOR 3KW AND

6KW FUEL CELL SYSTEMS (D2.1) .......................................................................................... 29 TABLE 11: PERFORMANCE REQUIREMENTS FOR THE EXTERNAL HEAT EXCHANGER TO BE DEVELOPED FOR 3KW AND

6KW FUEL CELL SYSTEMS .................................................................................................... 30 TABLE 12: DUTY CYCLE LIFE/AGEING TEST ..................................................................................... 31 TABLE 13: DUTY CYCLE LIFE AGEING TEST ..................................................................................... 32 TABLE 14: TEST CYCLES CHARACTERISTICS .................................................................................... 38 TABLE 15: DEFINITION OF CYCLES CHARACTERISTICS FOR TESTS AT EP ................................................. 39 TABLE 16: STANDARD ROUTINE .................................................................................................. 40 TABLE 17: DYNAMIC ROUTINE .................................................................................................... 40 TABLE 18: DEFINITION OF CYCLES CHARACTERISTICS FOR TESTS AT JRC .............................................. 42 TABLE 19: DEFINITION OF CYCLES CHARACTERISTICS FOR TESTS AT EPS .............................................. 45 TABLE 20: SEQUENCE OF LIFELONG TESTS ..................................................................................... 45 TABLE 21: T1=20°C, T3 VARIABLE, �3 VARIABLE, RH1 AND RH3 CONSTANTS ..................................... 48 TABLE 22: T1=40°C, T3 VARIABLE, �3 VARIABLE, RH1 AND RH3 CONSTANTS ..................................... 49 TABLE 23: T1=20°C, T3 VARIABLE, �1 VARIABLE, RH1 AND RH3 CONSTANTS ..................................... 50 TABLE 24: T1=40°C, T3 VARIABLE, �1 VARIABLE, RH1 AND RH3 CONSTANTS ..................................... 51 TABLE 25: T1=40°C, T3 VARIABLE, �1 AND �3 VARIABLE, RH1 AND RH3 CONSTANTS ........................ 52 TABLE 26: T1=20°C, T3 VARIABLE, �1 AND �3 VARIABLE, RH1 AND RH3 CONSTANTS ........................ 53 TABLE 27: HYDROGEN PUMP BEARING CHARACTERISTICS (DOMEL DATA) ............................................... 59 TABLE 28: RATING LIFE IN STANDARD CONDITIONS .......................................................................... 60 TABLE 29: RATING LIFE ............................................................................................................ 61 TABLE 30: RATING LIFE IN EXTREME CONDITIONS ............................................................................ 62 TABLE 31: RATING LIFE WITH A HIGHER AXIAL LOAD ........................................................................ 63 TABLE 32: DUTY CYCLE RATING LIFE ............................................................................................ 64 TABLE 33: BLOWER BEARINGS CHARACTERISTICS (DOMEL DATA) ......................................................... 64 TABLE 34: RATING LIFE IN STANDARD CONDITIONS (NMB 608) ......................................................... 65 TABLE 35: RATING LIFE IN STANDARD CONDITIONS (NMB 629) ......................................................... 66 TABLE 36: DUTY CYCLE RATING LIFE ............................................................................................ 67




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List of Figures FIGURE 1: PROCESS SCHEME - GRAPHIC REPRESENTATION OF POWER SYSTEM TO BE REALIZED WITH FLUMABACK

COMPONENTS .................................................................................................................... 9 FIGURE 2: AIR BLOWERS FINE CHARACTERIZATION TEST BENCH SCHEMATIC ............................................ 12 FIGURE 3: AERODYNAMIC PERFORMANCE OF MANUFACTURED PROTOTYPE AT DIFFERENT SPEED .................... 13 FIGURE 4: SCHEMATIC OF THE HYDROGEN RECIRCULATION PUMP FINE CHARACTERIZATION TEST BENCH ........ 15 FIGURE 5: AERODYNAMIC PERFORMANCE OF MANUFACTURED PROTOTYPE AT DIFFERENT SPEED .................... 17 FIGURE 6: VIBRATION SIGNAL WAVEFORM ...................................................................................... 20 FIGURE 7: SCHEMATIC OF THE HYDROGEN RECIRCULATION PUMP LIFE/AGEING TEST BENCH ........................ 21 FIGURE 9: HUMIDIFIER FINE CHARACTERIZATION TEST BENCH ............................................................. 26 FIGURE 10: SCHEME OF THE HUMIDIFIER ....................................................................................... 26 FIGURE 11: PRINCIPAL CHARACTERISTICS OF THE AGEING CYCLES ........................................................ 27 FIGURE 12: H2/AIR HEAT EXCHANGER FINE CHARACTERIZATION TEST BENCH ......................................... 29 FIGURE 13: GLYSANTIN/AIR HEAT EXCHANGER FINE CHARACTERIZATION TEST BENCH .............................. 30 FIGURE 14: LAYOUT OF FUEL CELL SYSTEM: “CLOSE BOX” AND “OPEN BOX” ........................................... 35 FIGURE 15: LOAD PROFILE ........................................................................................................ 37 FIGURE 16: PRINCIPAL CHARACTERISTICS OF THE INDIVIDUAL A CYCLE (15’ON /30’OFF LOAD) ................... 38 FIGURE 17: PRINCIPAL CHARACTERISTICS OF THE INDIVIDUAL B CYCLE (240’ON /30’OFF LOAD) ................. 38 FIGURE 18: PRINCIPAL CHARACTERISTICS OF THE INDIVIDUAL C CYCLE (4320’ON /30’OFF LOAD) ............... 39 FIGURE 19: PRINCIPAL CHARACTERISTICS OF THE INDIVIDUAL E CYCLE (480’ON /1’OFF LOAD) ................... 39 FIGURE 20: ODD GROUPS CYCLE SEQUENCE IN STANDARD ROUTINE, COMPOSED BY ONE B3 CYCLE FOLLOWED BY

THREE A3 CYCLES ............................................................................................................. 40 FIGURE 21: EVEN GROUPS CYCLE SEQUENCE, COMPOSED BY THREE A3 CYCLES FOLLOWED BY ONE B3 CYCLE .. 41 FIGURE 23: FIRST SEQUENCE, STRESS CONDITIONS ........................................................................ 44 FIGURE 24: SECOND SEQUENCE, STRESS CONDITIONS ...................................................................... 44 FIGURE 25: BLOWER PERFORMANCES ........................................................................................... 46 FIGURE 26: ENERGY FLOWS....................................................................................................... 54 FIGURE 27: BEARING LOAD ........................................................................................................ 56 FIGURE 28: PRINCIPAL CHARACTERISTICS OF H2 BEARINGS (MODEL 608-2Z) ......................................... 59




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List of abbreviations BoL Beginning of life BoP Balance of plant BoT Beginning of test EoL End of life EoT End of test FC Fuel cell PEM Polymer electrolyte or proton exchange membrane Rpm Revolutions (rounds) per minute FCT Fine characterization test LAT Life/ageing test PRT Periodical performance reference test




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1. INTRODUCTION

Overview of FluMaBack project

The FluMaBack (project abbreviation for Fluid Management component improvement for Back up fuel cell systems) project aims to improve the performance, life time and cost of BOP components of back up fuel cell (FC) systems specifically developed for emerging countries where long power black-outs occur (8-9 hours a day usually during working hours) and very demanding hard operation conditions are present often under extreme climate conditions and geographies (high ambient temperatures, high degree of ambient humidity, high air pollution, remote location, etc). Due to such requirements for long periods of back-up system operation (several hours almost each day) the improvement of sub-system components addressed in this project benefits both back-up and CHP (combined heat & power) fuel cell applications. The project focuses on new design and better operating BOP (balance of plant) components aiming at:

- Performance improvements in terms of reliability and efficiency; - Life improvements in terms of prolongation / extension both at component and system

level; - Cost reduction in a mass production perspective; - Process simplification of manufacture /assembly of the entire fuel cell system.

The project consortium consists of industries working together commercially, and being able to identify the critical needs based on their daily experience. This consortium in fact represents a real opportunity for developing a strategic alliance of industrial actors that in future can collaborate fostering the technological evolution of the components towards more efficient and flexible BOP components that will allow fuel cell industry to exploit the huge opportunities both for EU market and for emerging market economy countries (e.g. Brazil, China, Indonesia, India, Malaysia, Russia, Thailand, Vietnam, etc). The present project is therefore focused on the most critical BOP components with the largest potential for performance improvement and cost reductions as follows:

- Blower, - Recirculation pump, - Humidifier, and - Heat exchanger.

Relevant research institutes and universities support the industries in the development and evaluation of BoP components. The project activity is fully part of the call topic as it aims to improve availability and cost competitiveness of balance of plant (BoP) components, as well as their suitability for mass production to meet performance and lifetime targets (up to 10 years). As the industrial partners are actively supplying the fuel cell business, the project results can be implemented rapidly, enhancing the impact of the project Lifetime of such sub-system components has consequences not only on the performance of the individual component but on the performance of PEM fuel cell (polymer electrolyte fuel cell) stack, as well. Problems on robustness and durability on blower, pumps and humidifier can bring about damages on the membrane at PEMFC stack.




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Moreover it is important to evaluate the influence of the performance degradation of the BOP components (and their possible contamination effect) to the performance of the PEMFC stack. The target system of these R&D activities is a back-up fuel cell system specifically developed to face frequent and long periods of power black-outs (up to 8-9 hours per day) in emerging market economy countries. Lifetime of systems up to 10 years means more than 30,000 accumulated hours of system operation. Indeed, lifetime of back-up fuel cell system up to 10 years is guaranteed with lifetime of BOP components and fuel cell stack of 20,000 hours at nominal power in order to provide only one maintenance cycle. This means that the improvement of such sub-system components specifically designed for PEM fuel cell systems will advantage back-up systems as a first target application but could be benefit CHP applications too.




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2. TEST PROTOCOL The test protocol reports specific test procedures for each BoP component and fuel cell system in full accordance with manufacturers and the end-user in order to validate the performance criteria of the components concerned in the development here. The definition of the testing procedure includes also a strategy for performing accelerated tests on the components to validate anticipated lifetime. Specifically, an ageing model will be defined and agreed with manufacturers and end user.

Figure 1: Process Scheme - Graphic Representation of Power System to be realized with

Flumaback Components

The BOP components that will be tested are:

- Air blower (first and second release); - Hydrogen recirculation pump(first and second release); - Humidifier(first and second release); - Heat exchanger (first and second release).

The protocol includes 3 types of test for each these BOP components:

A) fine characterization test (FCT) particularly used for the first release of each BOP component

B) life/ageing test (LAT) C) periodical performance reference test (for validation purpose) (PRT)

The time available for the tests on first release BoP components using agreed test protocols to validate lifetime, durability/robustness and corrosion rates is 5 months (ref. Gantt Chart), while the first FC system release tests will last a maximum of 3 months.




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In this period 2 prototypes for each BoP component (for 3 kW and 6 kW fuel cell stacks) and 2 FC systems (3 and 6 kW) are to be characterized. In particular there will be two prototypes of air blowers and recirculation pumps available, one prototype for EP and one for Nedstack. The same blowers and recirculation pumps for 3 kW and 6 kW FC system will be tested. Based on results of BoP components testing we will prepare further prototypes for first FC system release tests. Separate components will be delivered (e.g. lamination material, magnets, bearings, impeller material …) to test and verify the impact of hydrogen. The time available for the tests on second release BoP components using agreed test protocols to validate lifetime, durability/robustness and corrosion rates is 11 months, while the second FC system release tests will last 11 months. The characterization of BoP components follows this procedure:

1) fine characterization test (FCT) 2) life/ageing test (LAT): 24h/24h, 7day/7day 3) periodical performance reference test (for validation purpose) (PRT).

In this period will be characterized 2 prototypes for each BoP component (for 3 kW or 6 kW fuel cell stacks). In the remaining 11 months tests of the FC system will be conducted according to this procedure:

- for 7 months 2 FC systems prototypes are tested (3 and 6 kW) at JRC and EP. JRC will use a climate chamber to perform tests in extreme climate situations (tropical environment).

- in the last 4 months ElectroPS will conduct a lifelong test using an accelerated procedure: frequent start up and shut down cycles, steep and rapidly changing load demand and longer cycles (72h) in parallel test setups (3 and 6 kW).




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2.1 Air blower and hydrogen pump (first releases) test protocol

2.1.1 Air blower fine characterization tests The new air supply system to be developed consists of an aerodynamic part centrifugal compressor and the electric motor that drives centrifugal compressor. The drive will be based on new brushless motor which is controlled by a DSP (digital signal processor) which allows great flexibility and dynamic operation of the system. The project targets of the air delivery system are:

- High blower efficiency (>30%) value at the working condition of fuel cell system; - miniaturized – compact design with integrated controller, - warranty for reliability at extreme ambient conditions (40°C and 70%RH); - sound pressure level below 60dB(A) assembled in fuel cell system; - size reduction due to an improvement of coupling between filter and blower in order to

facilitate assembling in fuel cell system; - lifetime 20,000h; - cost comparable with the industrialised blower currently used.

Table 1: Blower performance specification for 3 kW and 6 kW FC back-up power system




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The first release of the air blower will be tested using a fine characterization bench test system, in order to evaluate the performance and capabilities of the device in term of flow rate, pressure drop, temperature and energy consumption.

Figure 2: Air blowers fine characterization test bench schematic

The air compressor (or blower) takes in ambient air and delivers the necessary flow of air to support the operation of the fuel cell. For small fuel cell systems considered here, these compressors are powered by an electric motor. The power for the electric motor, PAC, is made available from the power converter through the system controller. Because a relatively large volume of air is needed to support the operation of the fuel cell, this element is one of the largest energy consuming loads on the system.

Table 2: Air blower test bench components and ranges

ID Description Model/Range

BLOWER Blower to test

ALIM AC/DC (power source) Alintel

MFM Flow meter FCI ST75V/ Air range: 0-40kg/h

V-01 Backpressure valve Samson 3241

TI-01÷02 inlet/outlet blower T TC (themo couple) K type

TI-03 Engine T inlet TC K TI-04 In driver engine T TC K TI-05 Outlet driver engine T TC K dPI Differential pressure transducer Rosemount 1151DP /0-700

mbar

P-01 Pressur trasducer Bourdon-Haenni /0-4 barg

Digital power meter

Digital power meter in order to evaluate the energy consumption (V, A, W)

Yokogawa WT230

piping Piping AISI 316 DN 40




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The tests are conducted assuming an open circuit and varying the pressure drop in the circuit with a backpressure valve (V-01). The power electronics and the motor cooling is carried out in a closed circuit connected with a plate heat exchanger cooled by tap water. The inlet temperature and outlet temperature of the air blower motor are monitored. The energy consumption of the electric motor is monitored by a digital power meter. In Figure 3 is reported a preliminary characterization done by Domel.

Figure 3: Aerodynamic performance of manufactured prototype at different speed

,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00 40,00

p [

kP

a]

Q [l/s]

Aerodynamic performance

15k rpm 17,5k rpm 20k rpm - measurement 22,5k rpm

The blowers speed is controlled via DC voltage 0-10V. The characterization’s tests consist of monitoring all operating parameters (air outlet flow rate, air pressure drop across inlet and outlet, air temperature inlet / outlet) at constant speed of the electric motor, varying the pressure drop across the circuit by backpressure regulation. In particular the tests are:

- 20 steps (each 0.5V) between 0-10V for the speed control, - At each step change of the pressure drop along the circuit,

- Data analysis.




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2.1.2 H2 recirculation pump fine characterization tests

The recirculation pump to be developed consists of a single motor that allows recirculation of both pure hydrogen and pure oxygen in two separate chambers, in order to manage two different chemical aggressive pure gases in the same device. Due to pressure oscillations in volumetric pumps and required high tolerances (hydrogen leakage) a centrifugal pump was selected. The project targets of the recirculation pump are:

- identification of the most proper materials inert to dump hydrogen and oxygen; for safety reasons stainless steel is currently preferred but also plastic materials will be investigated,

- identification of the most proper manufacturing technology (based on materials used and quantity predicted),

- currently several types of pumps are used for fuel cell applications, the focus is on constant fluid flow with minimal flow oscillations, so initial focus will be on centrifugal pump design,

- lifetime increase (from current 6,000 to about 20,000 hours) to be properly used in back-up application in emerging market economy countries, and

- cost comparable with the industrialised not specific pumps currently in use.

Table 3: H2 pump performance specification




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The first release of the recirculation pump will be characterized on a test bench system capable of measuring the performance of the device in terms of pressure drop, flow rate, temperature and energy consumption.

Figure 4: Schematic of the Hydrogen recirculation pump fine characterization test bench




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Table 4: Hydrogen pump test bench components and ranges

ID Description Model/Range

PUMP Pump to test

HEX Heat exchange gas/water

NV-01 Throttling valve Samson 3241-0

NV-02 Needle valve, piping filling

NV-03 Needle valve, piping emptying

NV-04 Control valve, control of water flow Samson 3321/kvs 1.6PT

NV-05 Needle valve, control of engine cooling

MFM Flow meter FCI ST75V/ H2 range: 0-12kg/h

TI-01÷02 Thermocouples along the circuit TC K

TI-03÷06 Thermocouples, inlet and outlet driver engine

TC K

dP Differential pressure transducer Rosemount 1151DP /0-700 mbar

PI-01÷02 pressure transducers, inlet and outlet pump pressure

Bourdon-Haenni /0-4 barg

Digital power meter

Digital power meter in order to evaluate the energy consumption (V, A, W)

Yokogawa WT230

piping Piping AISI 316 DN 40

In order to characterize the hydrogen pump and simulate the recirculating of unconsumed hydrogen, a closed mode test bench will be set. The tests could be conduced varying the pressure drops in the circuit with a throttling valve (NV-01) as to adjust the working pressure while attempting to limit pressure drop. Simultaneously the inlet pump pressure is adjusted to a constant value using two needle valves (NV-02 and NV-03) that allow pipe filling and purging. In the circuit a gas to liquid (water) heat exchanger (HEX-01) is inserted in order to ensure the inlet pump temperature remains at initially chosen conditions set for the test. The water cooling is by inserting a thermo regulator (NV-04) able to adjust the temperature of the inlet pump to accurately dose water flow through the valve. The valve is regulated using the TI-01 inlet pump temperature sensor. The power electronics and the motor cooling is carried out in a closed circuit connected with a water plate heat exchanger. The inlet and outlet temperature of the engine motor and that of the electronic components is monitored. Energy consumption is monitored / recorded using a digital power meter.

The pump speed is controlled via DC voltage 0-5V. The characterization’s tests consist of monitor all operating parameters (flow rate, pressure drop, temperature) at constant speed, varying the pressure drop with the throttling valve NV-01. In particular the tests are: - 13 steps (each 0.2V) between 2.5-5V for the speed control, - At each step change of the pressure drop along the circuit,

- Data analysis.




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In Figure 5 is reported a preliminary characterization done by Domel.

Figure 5: Aerodynamic performance of manufactured prototype at different speed

000

001

002

003

004

005

006

007

008

000 001 002 003 004 005 006

p [

kP

a]

Q [l/s]

Aerodynamic performance

17,5k rpm 20k rpm 22,5k rpm 25k rpm 27k rpm




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2.2 Air blower and hydrogen pump life/ageing test protocol

Life/Accelerated aging uses aggravated conditions of heat, pressure, vibration to speed up the

normal aging processes. It is used to help determine the long term effects of expected levels of

stress within a shorter time, usually in a laboratory environment under controlled standard test

conditions. It is used to estimate the useful lifespan of a product or its shelf life when actual

lifespan data are unavailable.

The main factors that cause failures are:

- ageing of the bearings;

- electronic failures.

Bearing failure is one of the foremost causes of breakdowns in rotating machinery and such failure

can be catastrophic, resulting in costly downtime.

2.2.1 Recirculation pump life/ageing test

Hydrogen pump materials can degrade over time due to corrosion, embrittlement and other physical phenomena caused by the chemical properties of the anode gas; proper tests will be developed and performed in order to evaluate the amount of solid particles generated by the friction of rotating parts in the impeller. In order to satisfy the target of 20,000 operational hours, accelerated ageing tests are performed in order to stress the blower and to evaluate any possible degradation. The second release of the hydrogen pump will undergo more comprehensive testing consisting of the following phases:

- Recirculation pump fine characterization - Life/ageing test - Performance reference test (for validation purpose)

In particular, bearing failure is one of the foremost causes of breakdowns in rotating machinery and such failure can be catastrophic, resulting in costly downtime. In operation, the dimensions of a bearing change as a result of structural transformations within the material. These transformations are influenced by temperature, time and stress. A bearing life calculator (SKF bearing calculator) will be used in order to fix severe conditions and evaluate the influence on the life of the component:

- high relative humidity of the reactants (hydrogen), - high operating temperature, - high rotating speed, - variable back-pressure.

Increase of pressure, temperature, flow rate and rotary speed is strictly related to the axial and radial load of the bearing, thus resulting in a different life expectancy.




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In the SKF life rating correlation the stress resulting from the external loads is considered together with stresses originated by the surface topography, lubrication and kinematics of the rolling contact surfaces. The influence on bearing life of this combined stress system provides a better prediction of the actual performance of the bearing in a particular application. Below four different calculations are shown varying: speed, temperature, lubrication conditions, level of contamination and dynamic bearing load, in order to evaluate the rating life of the bearings and evaluate the accelerated aging condition. In Sec. 3.2 the calculation is reported in detail. Rating life in standard conditions is calculated starting from the bearings characteristics, using the SKF correlation diagram:

Table 5: Hydrogen pump bearing characteristics (Domel data)

The SKF rating life, operating hours is 25800h. SECOND CONDITION: Rating life is calculated varying speed and temperature (20%overRPM=31200 rpm and 20%overT=132°C). The SKF rating life, operating hours is 8600h, accelerated ageing conditions: 3x required to access 25800hours. THIRD CONDITION (limit value): Rating life is calculated varying speed and temperature (RPMlimit=36000 rpm and Tlimit=160°C). The SKF rating life, operating hours is 2800h, accelerated ageing conditions: 9x required to access 25800hours. FOURTH CONDITION (higher dynamic load): Rating life is calculated varying speed and temperature (20%overRPM=31200 rpm and 20%overT=132°C) and increasing the axial load (effect mainly due to a high backpressure in the circuit). The SKF rating life is reduced to 1465h, accelerated ageing conditions: 18x required to access 25800hours.




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In order to analyze a correct rating life, the operating conditions, such as the magnitude and direction of loads, speeds, temperatures and lubrication conditions are continually changing. Within each duty interval, the bearing load and operating conditions can be averaged to some constant value. The number of operating hours or revolutions expected from each duty interval showing the life fraction required by that particular load condition should also be included. Under variable operating conditions, bearing life can be rated using this formula: �10� � 1/�1/�10�1 2/�10�2 3/�10�3�

Duty interval T,°C RPM

equivalent

dynamic

load , P

SKF rating

life, L10mh

time

fraction,U

resulting

SKF rating

life, L10mh

1 132 31200 0,127 8600 0,2

2277 2 160 36000 0,127 2800 0,4

3 132 31200 0,165 1465 0,4

Table 6: Duty cycle Rating Life

A periodical performance reference test will be conducted using the fine characterization test bench in order to monitor degradation of the component performance in term of flow rate, pressure drop, energy consumption and engine vibrations. Depending on the operating conditions and load, the resulting damage can be flattened areas on the rolling elements or indentations on the raceways. The indentations can be irregularly spaced around the raceway, or may be evenly spaced at positions corresponding to the spacing of the rolling elements. Permanent deformations usually lead to higher vibration and/or noise levels and increased friction. It is also possible that the internal clearance will increase or the character of the fits may be changed. Vibration signals are collected with a vibration sensor installed on the housing.

Figure 6: Vibration signal waveform




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A specific life/ageing test bench is built to operate on wet and heated / dry hydrogen gas. Its control unit manages data acquisition of the measured variables, H2 refilling in the circuit and guarantees implementation of safety actions in case of set alarm values, for example, too high temperature or pressure. In order to perform tests using cold hydrogen gas, the test bench will be operated inside a temperature controlled volume. The hydrogen filling consists of a solenoid valve and a pressure reducer to control circuit refilling. The humidification system consist of a bubbler in which the recirculated hydrogen is conveyed too. A control valve allows venting of hydrogen in case of the test ends and for safety reasons. The circuit is composed of a pressure digital sensor (indicator), located on the top of the bubbler, and four temperature sensors to measure: the ambient temperature, the water temperature in the bubbler, the outlet pump temperature and the temperature on the motor engine. This monitoring system allows 24h/7 testing.

Figure 7: Schematic of the Hydrogen recirculation pump life/ageing test bench




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2.2.2 Air blower life/ageing test

Compressors can degrade in performance over time as rotating components, especially bearings, wear down and surfaces become contaminated with air-borne dirt, dust and oils, and motor windings overheat and fail. In order to satisfy the target of 20,000 operation hours (life), will be conduced accelerated ageing tests in order to stress the blower and evaluate its possible degradation. The second release of the air blower will follow a more complex procedure consisting of the following phases:

- First air blower fine characterization - Life/ageing test - Performance reference test (for validation purpose)

A bearing life calculator (SKF bearing calculator) will be used in order to fix severe conditions and evaluate the influence on the life of the component:

- high operating temperature, - high rotating speed, - high back-pressure.

In Sec. 3.2 the calculation is reported in detail. Rating life in standard conditions is calculated starting from the bearings characteristics.

Table 7: Blower bearings characteristics (Domel data)

The SKF rating life, operating hours are 29240h (NMB 608) and 48000 (NMB 629). The bearing limiting is NMB 608, the following accounts will be made only on this bearing and they will be normalized to 20000h operational.




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SECOND CONDITION: Rating life is calculated varying speed and temperature (20%overRPM=24000 rpm and 20%overT=84°C). The SKF rating life, operating hours is 6660h, accelerated ageing conditions: 3x required to access 20000hours. THIRD CONDITION (limit value): Rating life is calculated varying speed and temperature (RPMlimit=36000 rpm and Tlimit=110°C). The SKF rating life, operating hours is 2220h, accelerated ageing conditions: 9x required to access 20000hours. FOURTH CONDITION (higher dynamic load): Rating life is calculated varying speed and temperature (20%overRPM=24000 rpm and 20%overT=84°C) and increasing the axial load (effect mainly due to a high backpressure in the circuit). The SKF rating life is reduced to 870h, accelerated ageing conditions: 23x required to access 20000hours. In order to analyze a correct rating life, the operating conditions, such as the magnitude and direction of loads, speeds, temperatures and lubrication conditions are continually changing

Duty

interval T,°C RPM

equivalent

dynamic

load , P

SKF

rating

life,

L10mh

time fraction,U

resulting

SKF rating

life, L10mh

1 84 24000 0,127 6660 0,2

1493 2 110 36000 0,127 2220 0,4

3 84 24000 4.04 870 0,4


A periodical performance reference test will be conducted using the fine characterization test bench in order to monitor degradation of the component performance in terms of flow rate, pressure drop, energy consumption and engine vibrations. Vibration signals are collected with a sensor installed on the housing. In order to characterize under critical conditions the blower’s tests will be performed in a climate chamber. A stable temperature water loop (T-05) is used to stabilize the air inlet. A back pressure valve V-01 is used to modify the pressure drop of the circuit. The temperature measured inside the chamber is influenced by radiation phenomena caused by the high temperature to which the blower’s body stabilizes, and in particular its fluid dynamics part, so some septa that force the flow to take a tortuous path are put inside the climate chamber. The climatic chamber is equipped with the following temperature probes (thermo couples):

- T-05: set point temperature exchanger - T -04: air inlet temperature - T-03: temperature air flow within the chamber - T-01: temperature near the intake filter - T-02: body temperature near the outlet




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and a valve V-01 in order to operate with a high backpressure.

Figure 8: Schematic of the Air blower’s life/ageing test




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2.3 Humidifiers test protocol The humidifier will be designed on a new concept to overcome tubular configurations with Nafion® tubes. A material selection will be performed to identify possible alternative materials. If not feasible, a new humidifier design employing Nafion® at different tube? size and shape (planar sheets) will be developed. The technical development objectives for the humidifier are mainly:

- optimal geometry design definition, - optimal connection to the fuel cell stack, - flexibility: current solutions consists of two (2) sizes: one (1) for humidification of air

equivalent to 250 l/min flow rate, one (1) for humidification of air flow equal to equivalent to 450 l/min flow rate. The target is a device that allows several sizes (minimum 4) according to the different power ranges of FC stacks, and

- cost: the current cost should be lower than 300 Euro/kW with a target of less than 100 Euro/kW.

3kW

AIR FLOW Q (Nl/min)

p (mbarg)

T (°C)

RH (%)

composition (%vol dry)

A02 humidifier primary flow inlet 300 170

21%O2 – 79%N2

A03 humidifier primary flow outlet

150 55 90

A04 humidifier secondary flow inlet 270 30 65 100 14%O2 - 86%N2

A05 humidifier secondary flow outlet

20 55 100

6kW

AIR FLOW Q

(Nl/min) p

(mbarg) T

(°C) RH (%) composition

(%vol dry)

A02 humidifier primary flow inlet 500 200 21%O2 –

79%N2 A03 humidifier primary flow outlet 165 55 90

A04 humidifier secondary flow inlet 450 45 65 100 14%O2 -

86%N2 A05 humidifier secondary flow outlet 30 55 100

Table 9: Humidifier performance specification




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2.3.1 Humidifier fine characterization test

Figure 9: Humidifier fine characterization test bench

The first release of the humidifier will be characterized on a dedicated bench test system, where air humidity can be controlled, by a separate thermodynamic equilibrium humidifier. The purpose of the test is a fine evaluation of the water transfer capabilities of the device from the wet to the dry stream. In order to realize the real operating conditions a system of thin film evaporation with a stage of super-saturation will be used, equipped with a mixer with the cathodic air and a temperature conditioning system.

Figure 10: Scheme of the humidifier

The tests can be performed sending in counter-flow the dry air and the wet air (excess air from the fuel cell) and analyzing all the operative conditions: air flow, pressure drop, temperature and relative humidity. A backpressure valve (V-01) simulates the pressure drops in the fuel cell.

Dry air (1)

De-humidifier air (4)

Wet air (3)

from FC

Humidifier air (2)

to FC V-01




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In this test bench air humidity can be controlled and modified enabling evaluation of the effective water mass transfer from the dry to the wet side of the humidifier.

2.3.2 Humidifier life/ageing test

The second release of the device, as for the other BoP components, will be tested using the following procedure:

- Initial characterization of the component

- Ageing test

- Periodical Reference Test (for validation purpose)

In order to evaluate accelerated ageing of the humidifier, it is tested under dry condition (air dew point 2°C) and in wet condition (saturated). Dry/humidified cycles will be repeated in order to accelerate degradation of water transport membranes.

1) Preliminar Life/ageing cycle at constant flow and temperature: - 2’ dry (air dew point 2°C) - 10’ wet (saturated) dry cycle in order to define the time within which the humidity drops to zero.

During the subsequent tests we use this new time for the dry cycles.

2) First sequence Life/ageing cycle: - x’ dry (air dew point 2°C) - 10’ wet (saturated)

repeated 10 times per day, at constant flow (50 Nl/min) and T (35°C).

3) STEP sequence: increasing flow rate steps (20 Nl/min per step) and Temperature (5°C per step).

Figure 11: Principal characteristics of the ageing cycles

A periodical test reference on the dedicated bench system measures the effective humidification capability of the system all along the life and the pressure drop along the two circuits. The tests on the system aim to characterize the humidification system under most critical operating conditions as typically occur during low power operation of the system when water production is at minimum due to the electrochemical reactions. Under such conditions it is appropriate to verify that the humidification system functions optimally to allow a high degree of proton conduction in the polymer membranes.




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2.4 Heat exchanger test protocol The development objectives for the heat exchanger are:

- ensure a fuel cell stack temperature of maximum 65 ºC with a maximum difference of 5 ºC between inlet and outlet during steady state and ensure a stack temperature during transient operation (e.g. ….) conform to the specified relative humidity range.

- internal cooling loop reduction in length: a reduction from 80 cm at present to a few cm of piping is targeted.

- reduction of thermal inertia: 20% reduction of thermal capacity is expected by improved management of and more rapid temperature changes for fuel cell stack.

- reduction of the number of tube / pipe connections: 4 connection could be eliminated with consequent simplification of assembly.

- internal heat dissipation: a reduction up to 10% of present internal heat to be dissipated is expected (e.g. for 6 kW of thermal power, 50 W to be dissipated internally are expected in comparison with current 500 W).

2.4.1 Heat exchanger fine characterization tests

The first release of the heat exchanger is tested on a dedicated test bench system in order to evaluate heat exchanging capabilities of the device, in order to check the general requirements of the component. As reported in deliverable 2.1 and in the process scheme will be used two heat exchanger:

- H2/Air heat exchanger in order to heat the pressure reducer outlet hydrogen stream;

- Air/glysantin external heat exchanger to cooling the stack.

3kW

AIR FLOW Q

(Nl/min)

p

(mbarg) T (°C)

RH

(%)

composition (%vol

dry)

A05

humidifier secondary

flow outlet - H2/AIR

heat exchanger inlet

270 20 55 100 14%O2 - 86%N2

A06

H2/AIR heat exchanger

outlet - power system

outlet

270 0 40 100 14%O2 - 86%N2

H02

pressure reducer

outlet - H2/AIR heat

exchanger inlet

62 0,27 20 H2 99,999%

H03a H2/AIR heat exchanger

outlet - stack inlet 62 0,22 35 H2 99,999%




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6kW

AIR FLOW Q

(Nl/min)

p

(mbarg) T (°C)

RH

(%)

composition (%vol

dry)

A05

humidifier secondary

flow outlet - H2/AIR

heat exchanger inlet

450 30 55 100 14%O2 - 86%N2

A06

H2/AIR heat exchanger

outlet - power system

outlet

450 0 40 100 14%O2 - 86%N2

H02

pressure reducer

outlet - H2/AIR heat

exchanger inlet

105 0,27 20 H2 99,999%

H03a H2/AIR heat exchanger

outlet - stack inlet 105 0,22 35 H2 99,999%

Table 10: Performance requirements for the H2/Air heat exchanger to be developed for 3kW

and 6kW fuel cell systems (D2.1)

MFC Air

Metering pump

Air

DemiWATER

Thin-film evaporator

MFC Air

saturator Thermal conditioning

H2/AIR Heat Exchanger

H2MFC H2

T-01

T-02

T-03

T-04

RH-01

AIR LINE

HYDROGEN LINEdP-01

H2 out

dP-02

Aria out

Figure 12: H2/Air heat exchanger fine characterization test bench

The H2/air heat exchanger heats the pressure reducer outlet hydrogen stream (to 35°C) and cools the power system outlet air (to 40°C). The first release of the H2/Air heat exchanger will be characterized on a dedicated bench test system, where air humidity is controlled by a separate thermodynamic equilibrium humidifier. In order to realize the real operating conditions a system of thin film evaporation with a stage of super-saturation is used, equipped with an air mixer and a temperature conditioning system. The H2 flow and air flow are controlled and regulated by a mass flow controllers. The characterization consists of evaluating the heat exchange efficiency defined as:

And the pressure drop along the circuits.




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Table 11: Performance requirements for the external heat exchanger to be developed for 3kW and 6kW fuel cell systems

FUN

Air cooling

Water/glysantin pump

T-02T-01

dP

Figure 13: Glysantin/Air heat exchanger fine characterization test bench

The first release of the glysantin/Air external heat exchanger is characterized on a dedicated bench test system (Figure 13). The second release of the devices is first characterized on the same test bench utilized in a fine characterization test to check whether the validation requirements are met. A specific lifelong test is performed in order to analyze degradation effects. In particular the ageing tests are performed 24h/24 recirculating glysantin and measuring the conductivity of the mixture.




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2.5 Test procedures

2.5.1 Air blower test procedures

First air blower release

First air blower release tests' duration: test duration within 5 months period Second air blower release

Second air blower release total tests’ duration: test duration within 11 months period

3 days: FCT (fine characterization test) 25 days: LAT (life ageing test,24h/24h) 2 days: PCT (periodical characterization test) 28 days: LAT (life ageing test,24h/24h) 2 days: PCT (periodical characterization test)

The procedure of LAT repeated in order to ensure the SKF rating life of 1500h.

Duty

interval T,°C RPM

equivalent

dynamic

load , P

SKF

rating

life,

L10mh

time fraction,U

resulting

SKF rating

life, L10mh

1 84 24000 0,127 6660 0,2

1493 2 110 36000 0,127 2220 0,4

3 84 24000 4.04 870 0,4

Table 12: Duty cycle life/ageing test

2.5.2 H2 pump test procedures

First release of recirculation pump

First release of recirculation pump tests’ duration: test duration within 5 months period In particular the tests are: - 13 steps (each 0.2V) between 2.5-5V for the speed control, - At each step change of the pressure drop along the circuit, - Data analysis.

Second release of recirculation pump

Second recirculation pump release tests’ duration: test duration within 11 months period

First 3 days: FCT (fine characterization test) 25 days: LAT (life ageing test,24h/24h) 2 days: PCT (periodical characterization test)




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28 days: LAT (life ageing test,24h/24h) 2 days: PCT (periodical characterization test)

The procedure of LAT repeated in order to ensure the SKF rating life of 2300h.


equivalent

dynamic

load , P

SKF rating

life, L10mh

time

fraction,U

resulting

SKF rating

life, L10mh

1 132 31200 0,127 8600 0,2

2277 2 160 36000 0,127 2800 0,4

3 132 31200 0,165 1465 0,4

Table 13: Duty cycle life ageing test

2.5.3 Humidifier test procedures

First release of humidifier First release of humidifier (3 and 6 kW) tests’ duration: 5 months

Second release of humidifier

Second humidifier release tests’ duration: 11 months

First 3 days: FCT (fine characterization test) 25 days: LAT (life ageing test,24h/24h) 2 days: PCT (periodical characterization test) 28 days: LAT (life ageing test,24h/24h) 2 days: PCT (periodical characterization test)

The procedure of LAT repeated in order to ensure the rating life of 2800h.




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2.6 Prototype of FC system test protocol The aim of the FluMaback is the development of sub-system components based on 3-6 kW PEM stacks developed for back-up application in emerging market economy countries, with long and frequent power black-outs (e.g. 8-9 hours per day). Back-up systems based on PEM fuel cell stacks have already reached a sufficient degree of technological maturity to be ready for market introduction in Europe and other Western Countries. However specific activities on BOP components aiming to improve their reliability, (useful) life and cost-competitiveness are still lacking both at the level of individual components and at system level. This compromises the vast adoption of PEM fuel cell systems in business continuity market in general and above all hinders to emploit the potential and enormous business opportunities in emerging economy market countries. Durability and reliability at severe operation conditions (high temperatures and high degree of humidity) is addressed in the component development due to the use of more stable materials, compact design and reliable assembly processes. Improved, corrosion-resistant materials are developed, evaluated and finally built into the FC power system. In system development, the target ‘durability’ corresponds to ‘extend operation range with lower (performance) degradation rate’.

In particular life and reliability tests are performed to evaluate the systems' performance and to optimize the interaction between BOP components (air blower, hydrogen recirculation pump, humidifiers, heat exchangers) and the fuel cell stack. The tests will be performed on realistic conditions (load profile, environment, start stops, effect of dynamic conditions). Test procedures used are those developed for the FCH-JU funded FITUP project. The tests will be conducted on two FC systems releases. First Release Test The targeted test period for the first release test is 3 months (from M17 to M19). In this period 2 FC systems prototypes will be tested (3 and 6 kW) in parallel test setups at EP. The full system is tested at EP as a “closed box” and “open box” using the same layout (see Fig.15 Layout for FC system: “closed box” and “open box”). In both configurations will be measured external parameters such as: voltage and current at fuel cell system terminals; current at batteries terminals; current at electronic load terminals and temperature of the FC system cabinet. During the “open box” characterization of the system will be used further measurement probes (additional measurement of air flow rate, of produced water, additional temperature sensors, etc.) to continuously monitor device / system output. Such necessity may in some way affect device integrity but is useful for later more in-depth investigations. The base test procedure reported in Sec. 2.6.3 will be followed. All operating parameter are logged by the device / system and analyzed in real time.

Second Release Test The targeted test period for the first release test is 11 months (from M24 to M34).




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In the first 7 months, 2 FC systems prototypes are tested (3 and 6 kW) at JRC and EP. The full system is tested at JRC as a “closed box” and “open box” using the same layout (see Fig. 15 Layout for FC system: “closed box” and “open box”). In both configurations will be measured external parameters such as: voltage and current at fuel cell system terminals; current at batteries terminals; current at electronic load terminals and temperature of the FC system cabinet. During the “open box” characterization of the system will be used further measurement probes (additional measurement of air flow rate, of produced water, additional temperature sensors, etc.) to continuously monitor device / system output. Such necessity may in some way affect device integrity but is useful for later more in-depth investigations. JRC will use a climate chamber to perform tests in extreme climate situations (tropical environment). The 2 FC systems (3 and 6 kW) will be characterized in succession. Some cycles performed on the first release will be followed by longer cycles (72h). As for the First Release Test at EP, all operating parameter are logged by the device / system and analyzed in real time.

The full systems are tested at EP, “closed box” and “open box” characterization tests are repeated for verification purposes. The base test procedure reported in Sec. 2.6.3 will be followed. All operating parameter are logged by the device / system and analyzed in real time.

In the last 4 months ElectroPS conducts a lifelong test using an accelerated test procedure comprising of frequent start up and shut down cycles, steep and rapidly changing load demand (rapid load cycles as defined in Sec. 2.6.5) and longer cycles (72h) in parallel test setups (3 and 6 kW).




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2.6.1 Fuel cell System layout

Figure 14: Layout of Fuel cell system: “close box” and “open box”

The main components of the fuel cell UPS systems are the following:

• PEM fuel cell(s) • fuel cell auxiliary equipments (air blower, water pump, power electronics, …) • start-up batteries (or ultracapacitors)

The “closed box” and “open box” test system is composed of the following parts, including external parameters:

• an industrial pc used to control the tests and collect the data through an acquisition board, equipped with necessary signal conditioning devices

• a temperature sensor used to measure the ambient temperature in the test area • one voltage signal to the acquisition board • three current signals (shunts) • an electronic load • an ac/dc converter for simulating the DC bus during normal operation • a controlled switch that breaks the connection between the AC/DC converter and the grid.




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The controlled variables in “closed box” and “open box” test systems are:

• external grid power availability (controlled through a controlled power switch) • load applied to the backup systems The monitored variables in “closed box” and “open box” test systems are: • voltage and current at fuel cell system terminals • current at batteries (or ultracapacitors) terminals • current at electronic load terminals • interior temperature of the FC system compartment / cabinet

The “open box” additional measurements are:

• produced water (measurement of the drained water) • additional temperature sensors along the heat exchanger, humidifier and external heat

exchanger During the “open box” test systems a periodic measurement with the infrared-camera will be performed, in order to monitor some critical components.

All external parameter and that internal to the device are recorded and analyzed in real time.

2.6.2 General test structure The tests will be performed on realistic conditions (load profile, environment, start stops, effect of dynamic conditions). The protocol includes different test cycles (a mix of simulated failures that represent the actual grid operation) and a load profile cycle in order to monitor the FC system performance. The three types of tests are:

- 1° test: LOAD PROFILE TEST

- 2° test: START and STOP TEST

- 3° test: DYNAMIC PROFILE TEST

1°LOAD PROFILE TEST The aim of this test is to verify the response of FC System to small load variation. The first test sequence consists of changing load (power) demand simulated using a resistive electrical load. The current response of the FC system to the change in load being 0.5 kW per 5 minutes step from 0 kW to 3 KW (6 kW) and back to 0 kW is recorded ( Figure 15 below for the load profile).




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Figure 15: Load profile

2° START and STOP TEST

The main target of these tests is the evaluation of FC system behaviour in case of grid failures. These tests should confirm the functionality, reliability and performance of the system. In particular different grid failures are simulated, divided in three main groups, each one is characterized by a different duration and represents a statistical class of failures that actually occur in reality. Test procedures used are derived by the concepts developed in the FCH-JU project FITUP:

• short term grid failures (A type), duration of 15 minutes • medium grid failures (B type), duration of 240 minutes (4 hours) • catastrophic grid failures (C type), duration of 4320’ (72 hours)

An additional grid failure, defined for a specific FLUMABACK Project need:

• long term grid failures (E type), duration of 480 minutes (8 hours) B, C and E type simulations have a larger duration compared to the actual grid failures of the same class. The duration of B failures has been fixed in order to create test procedures respecting the given number of on-off cycles and hours of operation. E type is an additional grid failure (not developed during FITUP Project). It will be performed during the laboratory tests at EP. C simulations are larger than real world ones, the resulting tests are more stressing for the systems than usual functioning. As a consequence, if the systems will be able to withstand the programmed tests, they will prove to be capable of working in harder conditions than normal operation in Europe. C type will be performed during the climate chamber tests at JRC and during lifelong tests conduced by EPS.




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The protocol performed in FITUP project provides two different start-up conditions: • warm start up (1 type), with an off period duration prior to the cycle of 1 minute • cold start up (2 type), with an off period duration prior to the cycle of 60 minutes In order to perform the analysis during FLUMABACK project an only start up condition will be employed:

• cold start up (3 type), with an off period duration prior to the cycle of 30 minutes. 3° DYNAMIC PROFILE TEST In order to simulate different grid requests, the same tests are performed at different power levels namely 50%, 75% and 100% of total system power. This will be done only during the E type simulation at EP. The characteristics of the simulations and their frequency are indicated in the following table.

Cycle type A1 A2 A3* B1 B2 B3* C1 C2 C3* E3*

Total duration

per cycle (min)

15 15 15 240 240 240 4320 4320 4320 480

off period

(min) 1 60 30 1 60 30 1 60 30 30

Performed in

EP, JRC,

EPS

EP, JRC,

EPS

JRC,

EPS EP, JRC

Table 14: Test cycles characteristics

*cycles performed during the FLUMABACK project.

Figure 16: Principal characteristics of the individual A cycle (15’on /30’off load)

Figure 17: Principal characteristics of the individual B cycle (240’on /30’off load)




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Figure 18: Principal characteristics of the individual C cycle (4320’on /30’off load)

Figure 19: Principal characteristics of the individual E cycle (480’on /1’off load)

2.6.3 First and second release test at EP_ Base test procedure These tests will be performed in laboratory and have the main purpose of supplying reference data. The test is performed according to the following set of load sequences:

Cycle name A3 B3 E3

cycle duration (min) 15’ 240’ 480’

Off period before cycle start

(min) 30’ 30’ 30’

N° cycles at 50% power 24 8 4

n° cycles at 75% power 24 8 4

n° cycles at 100% power 24 8 4

Total number of cycles 72 24 12

Total on hours 18 96 96

Table 15: Definition of cycles characteristics for tests at EP

A and B cycles will be performed following sequence of simulation groups, named standard routine. Every group of the sequence contains less than 8 hours of total test time (sum of on and off periods, counted from the first start up to the last shut down of the day), therefore it can be contained in a standard working day.




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Group 1 2 3 4 5 6

Cycle order B3 → 3 A3 3 A3 → B3 B3 → 3 A3 3 A3 → B3 B3 → 3 A3 3 A3 → B3

N° of A3 3 3 3 3 3 3

N° of B3 1 1 1 1 1 1

Total time 405 405 405 405 405 405

Power level 75% 75% 100% 100% 50% 50%

Table 16: Standard routine

Every time the standard routine is performed, three E-cycles must be carried on. The order of E cycles is arbitrary, but all the cycles enumerated in table must be done.

At the end of the three E-cycles, a dynamic routine is performed as below:

Table 17: Dynamic routine

Each sequence consists of:

- one standard routine,

- three E-cycles

- a dynamic routine and it will repeated 4 times. At the start and at the end of all sequences a load profile will be performed in order to verify the response of FC System to small load variation. The second and fourth sequence will be done with the “open box” test systems, analyzing additional variables.

Figure 20: Odd groups cycle sequence in standard routine, composed by one B3 cycle followed

by three A3 cycles

Group 1 2 3

Cycle order B3 → 3 A3 B3 → 3 A3 B3→ 3 A3

N° of A3 (50%) 0 0 0

N° of B3 (50%) 1 0 0

N° of A3 (75%) 0 0 0

N° of B3 (75%) 0 1 0

N° of A3 (100%) 3 3 3

N° of B3 (100%) 0 0 1

Total time 405’ 405’ 405’




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Figure 21: Even groups cycle sequence, composed by three A3 cycles followed by one B3 cycle

During the laboratory tests, a noise measurement will be conduced. Noise level measurements utilizing:

- a microphone, the interface between the acoustic field and the measuring system, put a meter in front of the fuel cell;

- an electronic amplifier and calibrated attenuator for gain control;

- a frequency weighting or analyzing possibilities. During the laboratory tests, an evaluation of hydrogen consumption will be conduced. The evaluation of the hydrogen consumption of the systems (and therefore the estimate of their efficiency) will be carried on through gravimetric measurements of the hydrogen tank used to feed the systems. In fact, this method assures the highest level of accuracy. These measurements will be operated using a precision balance with a minimum accuracy of 1g. A special procedure was defined: 4 A3 cycles, performed at 4 different constant power levels (25%, 50%, 75%, 100% of total system power). The whole procedure is graphically represented in below.

Figure 22 - Hydrogen consumption evaluation test cycle sequence

During the 60’ of system inactivity between subsequent cycles, the hydrogen tank used to feed the system will be weighed. The tank should be placed directly on the balance, in order to weigh it without moving any part of the system. If this will not be possible, maximum care should be used during the disconnection of the tank from the system in order to avoid changes in tank weight not depending on hydrogen consumption. The weighing of the tank should be operated after that any hydrogen flow to the




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fuel cell vanishes (there is flow for some time also after system stop). The whole procedure will be completed using a single hydrogen tank (10 l, 200 bar, approximately 2 Nm3). The procedure will be done for each system (3 and 6 kW) 3 times during the tests at EP: at the beginning, after the 2° repetition and at the end.

2.6.4 Second FC system Release Test at JRC_climatic chamber tests

An integrated environmental test system consisting of a walk-in climate chamber (ambient temperature in the range -40 °C/+60 °C, humidity up to 95%) is available at JRC. This chamber will be used to perform tests in extreme climate situations (tropical environment). During the preparation of a test inside the climate chamber, it is important to avoid any substantial modification of the tested system. Therefore, it is strongly recommended to connect the test equipment to the system in a way that it can be moved in and out from the chamber without any component disconnection.

Climate chamber tests in extreme environmental conditions will be performed at JRC in tropical environment continuous operation (45 °C and 70 % RH).

During the climate chamber tests, C simulations are executed for a period of 72 hours: these operating conditions are more stressing compared to the real ones. Every test sequence will start with a 5 hours stand-by period inside the climate chamber in order to stabilize the temperature condition of the system. After stabilization the grid failure sequence will start, following the same procedure applied in EP, but always at 100% of power: this will result in a more stressing condition for the system.

The cycles carried on during climate chamber tests are:

Cycle name A3 B3 E3 C3

cycle duration (min) 15’ 240’ 480’ 4320’

Off period before cycle start

(min) 30’ 30’ 30’ 300’

n° cycles at 100% power 24 8 4 12

Total on hours 6 32 32 864

Table 18: Definition of cycles characteristics for tests at JRC

Each sequence consists on:

- 3 A3-cycles and 1 B3-cycle repeated 2 times

- 1 E3-cycle

- 3 C3-cycles and it will repeated 4 times. The second and fourth sequence will be done with the “open box” test systems, analyzing additional variables.

The climate chamber tests will be carried on in the following way:




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• the UPS is placed inside the chamber, connected to the grid and to the load, with load set at maximum UPS power

• the environment conditions are set

• after the temperature inside the chamber reaches the desired value, the UPS is kept in stand-by for at least 5 hours.

• test sequence start




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2.6.5 Second FC system Release Test at EPS_lifelong tests

ElectroPS will conduct a lifelong test using an accelerated procedure: frequent start up and shut down cycles, steep and rapid load cycling of short duration per cycle and longer cycles (72h) in parallel test setups (3 and 6 kW). The stress cycles are composed by two sequences. FIRST SEQUENCE: 3 cycles composed by 5 start-ups and 5 shut-downs, alternatively repeated every 10 minutes (i.e. each cycle implies 5 repetitions of 10’ ON/10’ OFF sequence). Between subsequent cycles the waiting time is 30’. 15 on-off cycles per day are performed.

Figure 23: First sequence, stress conditions

SECOND SEQUENCE: 3 cycles made of 5 start-ups and 5 shut-downs, alternatively repeated every 5 minutes (i.e. each cycle implies 5 repetitions of 5’ ON/5’ OFF). Between subsequent cycles the waiting time is 30’. 15 on-off cycles per day are performed.

Figure 24: Second sequence, stress conditions

The electronic load is set at maximum UPS power during both sequences.




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The cycles carried on during lifelong tests are:

Cycle name A3 B3 C3 10’ON/

10’OFF

5’ON/

5’OFF

cycle duration (min) 15’ 240’ 4320’ 10’ 5’

Off period before

cycle start (min) 30’ 30’ 300’ 10’ 10’

n° cycles at 100%

power 12 4 11 75 75

Total on hours 3 16 792 12,5 6,25

Table 19: Definition of cycles characteristics for tests at EPS

Each sequence consists on:

- Stress cycles: 15 on/off (10’on/10’off), 15 on/off (5’on/5’off) x 5

- 3 C3-cycles (at 100% power) and it will repeated 3 times. At the beginning and at the end of the lifelong tests this sequence will be performed:

- 3 A3-cycles and 1 B3-cycle repeated 2 times

- 1 C3-cycle at 100% of power.

duration,

h 13,5 77 80 231 80 231 80 231 13,5 77

cycles (3A3 1B3)

X2 1 C3

stress

cycle 3 C3

stress

cycle 3 C3

stress

cycle 3 C3

(3A3 1B3)

X2 1 C3

Table 20: Sequence of lifelong tests




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3. DATA ANALYSIS & RESULTS INTERPRETATION

3.1 Performance evaluation criteria for the individual components and FC system

3.1.1 Performance evaluation of the air blower The blowers speed is controlled via DC voltage 0-10V. The characterization’s tests consist of monitoring all operating parameters (air outlet flow rate, air pressure inlet /outlet, air temperature inlet / outlet) at constant speed of the electric motor, varying the pressure drop across the circuit by backpressure regulation. In particular the tests are organized as:

− 20 steps (each 0.5V) between 0-10V for the speed control, − At each step change of the pressure drop along the circuit, − Data analysis.

Figure 25: Blower performances

Blower performance may be evaluated from the following equation:

Equation 1: Blower efficiency � � � � �� ∗ ��

�� 1�

The term η is the blower efficiency, assuming an adiabatic process. The term k is the ratio of specific heats, cp/cv, which for air is commonly taken at 1.40. The temperature and pressure




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terms represent the conditions at the inlet and discharge of the blower, and may further be characterized by static or total measurements. For example, it is customary to present pressure ratio as a static-to-total measurement, or total-total, etc., with corresponding total or static temperature measurements. Note also that compressor efficiency can be evaluated directly from the pressure and temperature rise across the compressor stage. Since an adiabatic process is assumed, a comparison against an ideal (isentropic) process can be made, the difference between the two being influenced by the “isentropic efficiency”, η.

3.1.2 Performance evaluation of the H2 pump

The pump speed is controlled via DC voltage 0-5V. The characterization’s tests consist of monitor all operating parameters (H2 flow rate, pressure pressure inlet /outlet, air temperature inlet / outlet) at constant speed, varying the pressure drop along the circuit. In particular the tests are organized as:

- 13 steps (each 0.2V) between 2.5-5V for the speed control, - At each step change of the pressure drop along the circuit, - Data analysis.

During the fine characterization leakage tests are performed.

3.1.3 Performance evaluation of the Humidifier

The tests are carried out with the logic to vary, as far as possible, only one parameter at a time.

The variables that define the test conditions are: the two air flows (dry side_�� and wet side_�� ) the inlet temperatures (dry side_ � and wet side_ �) and the inlet humidity (dry side__� � and wet side_� �). In the test campaign, this set of parameters is fixed: inlet temperature dry side_ � and wet side_ �, inlet relative humidity dry side__� � and wet side_� �. The tests allow to study the effects on: the outlet temperatures ( � and !), the outlet humidity

(� � and � ! ) according to the following procedures: a) dry air flow constant and wet air flow variable in a defined interval; b) wet air flow constant and air flow shell side variable within a defined interval; c) dry and wet air flow variables within a defined interval maintaining, as far as possible, a ratio of about unity between the two flows; According to Tab. 15, the tests for 3kW humidifier are organized as:

- Inlet dry air T1 variable (20°C and 40°C); - Inlet wet air T3 variable (between 20°C and 80°C); - RH1 = 40%; - RH3 = 100%; - Dry and wet air flows variable between 50 l/min and 300 l/min (steps of 50 l/min).




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1° TEST

inlet T1

(dry), °C

inlet T3

(wet),°C

m1̇ (dry

flow),l/min

m3 (wet

flow),l/min RH1(%) RH3 (%)

20 20

50

variable

50-300

40 100

100

variable

50-300

150

variable

50-300

200

variable

50-300

250

variable

50-300

300

variable

50-300

2° TEST 20 40

50

variable

50-300

40 100

100

variable

50-300

150

variable

50-300

200

variable

50-300

250

variable

50-300

300

variable

50-300

3° TEST 20 60

50

variable

50-300

40 100

100

variable

50-300

150

variable

50-300

200

variable

50-300

250

variable

50-300

300

variable

50-300

4° TEST 20 80

50

variable

50-300

40 100

100

variable

50-300

150

variable

50-300

200

variable

50-300

250

variable

50-300

300

variable

50-300

Table 21: T1=20°C, T3 variable, "#� variable, RH1 and RH3 constants




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5° TEST

inlet T1

(dry),

°C

inlet T3

(wet),°C

m1̇ (dry

flow),l/min

m3 (wet


40 20

50 variable

50-300

40 100

100 variable

50-300

150 variable

50-300

200 variable

50-300

250 variable

50-300

300 variable

50-300

6° TEST 40 40

50 variable

50-300

40 100

100 variable

50-300

150 variable

50-300

200 variable

50-300

250 variable

50-300

300 variable

50-300

7° TEST 40 60

50 variable

50-300

40 100

100 variable

50-300

150 variable

50-300

200 variable

50-300

250 variable

50-300

300 variable

50-300

8° TEST 40 80

50 variable

50-300

40 100

100 variable

50-300

150 variable

50-300

200 variable

50-300

250 variable

50-300

300 variable

50-300

Table 22: T1=40°C, T3 variable, "#� variable, RH1 and RH3 constants




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9° TEST

inlet T1

(dry), °C

inlet T3

(wet),°C

m1̇ (dry

flow),l/min

m3 (wet


20 20

variable

50-300 50

40 100

variable

50-300 100

variable

50-300 150

variable

50-300 200

variable

50-300 250

variable

50-300 300

10° TEST 20 40

variable

50-300 50

40 100

variable

50-300 100

variable

50-300 150

variable

50-300 200

variable

50-300 250

variable

50-300 300

11° TEST 20 60

variable

50-300 50

40 100

variable

50-300 100

variable

50-300 150

variable

50-300 200

variable

50-300 250

variable

50-300 300

12° TEST 20 80

variable

50-300 50

40 100

variable

50-300 100

variable

50-300 150

variable

50-300 200

variable

50-300 250

variable

50-300 300

Table 23: T1=20°C, T3 variable, "$� variable, RH1 and RH3 constants




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13° TEST

inlet T1

(dry), °C

inlet T3

(wet),°C

m1̇ (dry

flow),l/min

m3 (wet


40 20

variable 50-

300 50

40 100

variable 50-

300 100

variable 50-

300 150

variable 50-

300 200

variable 50-

300 250

variable 50-

300 300

14° TEST 40 40

variable 50-

300 50

40 100

variable 50-

300 100

variable 50-

300 150

variable 50-

300 200

variable 50-

300 250

variable 50-

300 300

15° TEST 40 60

variable 50-

300 50

40 100

variable 50-

300 100

variable 50-

300 150

variable 50-

300 200

variable 50-

300 250

variable 50-

300 300

16° TEST 40 80

variable 50-

300 50

40 100

variable 50-

300 100

variable 50-

300 150

variable 50-

300 200

variable 50-

300 250

variable 50-

300 300

Table 24: T1=40°C, T3 variable, "$� variable, RH1 and RH3 constants




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17° TEST

inlet T1

(dry), °C

inlet T3

(wet),°C

m1̇ (dry

flow),l/min

m3 (wet


40 20

50 50

40 100

100 100

150 150

200 200

250 250

300 300

18° TEST 40 40

50 50

40 100

100 100

150 150

200 200

250 250

300 300

19° TEST 40 60

50 50

40 100

100 100

150 150

200 200

250 250

300 300

20° TEST 40 80

50 50

40 100

100 100

150 150

200 200

250 250

300 300

Table 25: T1=40°C, T3 variable, "$� and "#� variable, RH1 and RH3 constants




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21° TEST

inlet T1

(dry), °C

inlet T3

(wet),°C

m1̇ (dry

flow),l/min

m3 (wet


20 20

50 50

40

100

100 100

150 150

200 200

250 250

300 300

22° TEST 20 40

50 50

40

100

100 100

150 150

200 200

250 250

300 300

23° TEST 20

60

50 50

40

100

100 100

150 150

200 200

250 250

300 300

24° TEST 20 80

50 50

40

100

100 100

150 150

200 200

250 250

300 300

Table 26: T1=20°C, T3 variable, "$� and "#� variable, RH1 and RH3 constants




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According to Tab. 15, the tests for 6kW follow the same procedures listed above: - Inlet dry air T1 variable (20°C and 40°C); - Inlet wet air T3 variable (between 20°C and 80°C); - RH1 = 40%; - RH3 = 100%;

Dry and wet air flows variable between 100 l/min and 500 l/min (steps of 100 l/min). The performances analysis consist on the evaluation of the effective water mass transfer from the dry to the wet side of the humidifier varying temperature and air flow.

3.1.3 Performance evaluation of the FC system

Data acquired and analyzed during the FC system tests are: IFC, Ibat, Iload, VFC.

Figure 26: Energy flows

There are three ways for energy flow in the system as described in the below figure. Blue flow is from H2 energy converted to electrical energy in the fuel cell and consumed by the load. Green flow is the grid energy absorbed by the batteries from via rectifiers and consumed by the load. Red flow is the H2 energy converted into electrical energy which is then transferred to the batteries by FC charging the parallel connected batteries, then consumed by the load. In EPS system DC/DC prevents FC charging the batteries after the transient period, so the red flow is less significant. There are two components of performance degradation: fuel cell degradation and battery degradation. In a sufficiently long operation this will be dominated by fuel cell degradation. H2 consumption test results will be a good estimate about performance degradation of the entire system because this will cover the energy flows as represented with blue and red lines in the above figure. However, by choosing H2 consumption as the performance degradation parameter we are neglecting the battery degradation component (green flow). So we need to justify that blue and red flows are sufficiently larger than green flow.

FC

Batt

Load

H2

AC




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3.2 Lifetime validation & aging model for individual component and FC system

3.2.1 Lifetime validation model for air blower and H2 pump

Life/Accelerated aging is testing that uses aggravated conditions of heat, pressure, vibration,

etc. to speed up the normal aging processes of items. It is used to help determine the long term

effects of expected levels of stress within a shorter time, usually in a laboratory by

controlled standard test methods. It is used to estimate the useful lifespan of a product or its shelf

life when actual lifespan data is unavailable.

The main factors that cause failures are:

- ageing of the bearings;

- electronic failures.

Bearing failure is one of the foremost causes of breakdowns in rotating machinery and such failure

can be catastrophic, resulting in costly downtime. The life of a rolling bearing is expressed as the number of revolutions or the number of operating hours at a given speed that the bearing is capable of enduring before the first sign of metal fatigue occurs on a raceway of the inner or outer ring or a rolling element. Bearing life is usually expressed as the number of hours an individual bearing will operate before the first evidence of metal fatigue develops in the rings or rolling elements. In past years, four different terms were used when referring to bearing life. The American Bearing Manufacturers Association (ABMA), formerly the AFBMA defines the Basic Rating Life, L10 as the bearing life associated with a 90% reliability when operating under conventional conditions, i.e. after a stated amount of time 90% of a group of identical bearings will not yet have developed metal fatigue. L10 life is also referred to by manufacturers as the 'minimum expected life'. Calculating loads The basic dynamic load rating covers dynamically stressed bearings that rotate under load. This rating, defined in ISO 281, is the bearing load that results in a basic rating life or L10 of 1 million revolutions. Dynamic loads should include a representative duty cycle or spectrum of load conditions and any peak loads. The basic static load rating applies to bearings that rotate at speeds less than 10 rpm, slowly oscillate, or remain stationary under load over certain periods. Be sure to include loads of extremely short duration (shock) because they may plastically deform contact surfaces and compromise bearing integrity. Classical mechanics along with known or calculable external forces are used to calculate the loads acting on a bearing. These external forces may include resultants from power transmission, shaft or housing supports, or inertia. When calculating loads on a single bearing, assume the shaft to be a beam resting on rigid, moment-free supports. Basic catalog or simplified calculations typically ignore elastic deformations in the bearing, housing, or machine frame, as well as moments produced in the bearing by shaft deflection. Such




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calculations may assume loads are constant in magnitude and direction and act radially on a radial bearing, or axially and centrically on a thrust bearing. Oftentimes, bearings in actual service see simultaneous radial and axial loads. When the resultant of radial and axial loads is constant in magnitude and direction, calculate an equivalent dynamic bearing load from: P = XFr + YFa where P = equivalent dynamic bearing load, kN; Fr = actual radial bearing load, kN; Fa = actual axial bearing load, kN; X = radial load factor for the bearing; and Y = axial load factor for the bearing.

Figure 27: bearing load

For single-row radial bearings, axial load influences P only when the ratio Fa ⁄ Fr exceeds a certain limiting value. Conversely, even light axial loads are significant for double-row radial bearings. The above equation also applies to spherical thrust bearings and other thrust types that handle both axial and radial loads. Be sure to consult manufacturer catalogs for axial-radial thrust bearings because designs can vary widely. For thrust ball bearings and other types that carry pure axial loads, the equation simplifies to P = Fa, provided the load acts centrically.




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Rating life equations The basic rating life of a bearing in accordance with ISO281 is: L10 = (C ⁄P)

p basic rating life (at 90% reliability) (million revolutions) where C = basic dynamic load rating, kN; P = equivalent dynamic bearing load, kN; p = life-equation exponent ( p = 3 for ball bearings; and p = 10/3 for roller bearings) For bearings run at constant speed, it may be more convenient to express the basic rating life in operating hours: L10h = (10

6/60n) L10 basic rating life (at 90% reliability) (operating hours) where n = rotational speed, rpm Predicted bearing life is a statistical quantity in that it refers to a bearing population and a given degree of reliability. The basic rating life is associated with 90% reliability of bearings built by modern manufacturing methods from high-quality materials and operated under normal conditions. In practice, predicted life may deviate significantly from actual service life, in some documented cases by nearly a factor of five. Service life represents bearing life in real-world conditions, where field failures can result from root causes other than bearing fatigue. Examples of root causes include contamination, wear, misalignment, corrosion, mounting damage, poor lubrication, or faulty sealing systems. Ongoing advances in bearing technology and manufacturing processes continue to extend bearing life and reduce sensitivity to severe operating conditions. Standard ISO 281 has developed in step with these advances to predict service life more accurately. The latest version expands coverage to include bearing material fatigue stress limits, and a factor for solid contamination effects on bearing life when using various lubrication systems such as grease, circulating oil, and oil bath. For modern high quality bearings, the basic rating life can deviate significantly from the actual service life in a given application. Service life in a particular application depends on a variety of influencing factors including lubrication, the degree of contamination, proper installation and other environmental conditions. Therefore, ISO 281 uses a modified life factor to supplement the basic rating life. The SKF life modification factor aSKF applies the same concept of a fatigue load limit Pu as used in ISO 281. Values of Pu are listed in the product tables. Like ISO 281, the SKF life modification factor aSKF takes the lubrication conditions and a factor hc for the contamination level into consideration to reflect the operating conditions using: Lnm= a1aSKF L10 where a1 = life-adjustment factor for reliability (1.0 for 90% reliability); and aSKF = manufacturer life modification factor according to ISO 281. SKF (main designer of bearings) has a free bearing life calculator: http://webtools3.skf.com/BearingCalc/selectedCalculation.action?selectedCalculationID=1&selectedCalculationName=Bearing%20life It will be used in order to analyze the bearing life.




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In the SKF life rating equation the stress resulting from the external loads is considered together with stresses originated by the surface topography, lubrication and kinematics of the rolling contact surfaces. The influence on bearing life of this combined stress system provides a better prediction of the actual performance of the bearing in a particular application. Below four different calculations are shown varying: speed, temperature, lubrication conditions, level of contamination and dynamic bearing load, in order to evaluate the rating life of the bearings. H2 RECIRCULATION PUMP FIRST STANDARD CONDITION: Rating life in standard conditions is calculated starting from the bearings characteristics.




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Table 27: Hydrogen pump bearing characteristics (Domel data)

Figure 28: Principal characteristics of H2 bearings (model 608-2z)

ASONIC HQ 72-102 is a synthetic high-temperature lubricating grease (-40°C/+180°C). Due to the careful selection of product components and the clean manufacturing environment, ASONIC HQ 72-102 is a rolling bearing grease with a particularly low noise level. In Table 34 are reported the calculation of the rating life (L10 and L10h) and in particular is introduced the askf manufacturer life modification factor according to ISO 281. It depends on lubrification conditions (ηc, Pu, k).

The SKF rating life, operating hours is 25800h.




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inlet value_standard condition

Fr, kN 0,005 radial load

Fa, kN 0,07 axial load

n, rpm 26000 speed

T, °C 110

grease ASONIC HQ 72-102

viscosity, mm2/s

100 (40°C)

12 (100°C)

C,kN 3,45 basic dynamic load rating

C0,kN 1,37 basic static load rating

results

P,kN 0,127 Equivalent dynamic bearing load

C/P 27,2 Load ratio

L10=(C/P)^3 20124 Basic rating life (at 90% relaibility), million

revolutions

L10h=106/(60*n)*L10 12900 Basic rating life, operating hours

v1,mm2/s 7,5

rated viscosity of lubrificant, depends on

bearing mean diameter and rotational speed,

ref.diagram

v,mm2/s 10 actual operating viscosity of the lubrificant,

mm2/s, ref diagram

k=v/v1 1,33 viscosity ratio

ηc 0,6 factor for contamination level, "high

cleanliness", sealed bearing :ηc=0,8

askf 2 SKF life modification factor aSKF

Pu,kN 0,057 Fatigue load limit

Pu/P 0,45

ηcPu/P 0,27

L10m=a1*askf*L10 40247 SKF rating life, million revolutions

L10mh=106/(60*n)*L10m 25800 SKF rating life, operating hours

Table 28: Rating Life in standard conditions

SECOND CONDITION: Rating life is calculated varying speed and temperature (20%overRPM=31200 rpm and 20%overT=132°C). In Table 35 are reported the calculation of the rating life (L10 and L10h) and the SKF rating life. The SKF rating life, operating hours is 8600h, accelerated ageing conditions: 3x required to access 25800hours.




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inlet value_20%overRPM_20%overT



n, rpm (20%overspeed) 31200 speed

T, °C (20%overtemperature) 132


viscosity, mm2/s

100 (40°C)

12 (100°C)



results


C/P 27,2 Load ratio


revolutions


v1,mm2/s 6

rated viscosity of lubrificant, depends on bearing

mean diameter and rotational speed, ref.diagram

v,mm2/s 8 actual operating viscosity of the lubrificant, mm

2/s,

ref diagram


ηc 0,3 factor for contamination level, "high cleanliness",

sealed bearing :ηc=0,8

askf 0,8 SKF life modification factor aSKF

Pu,kN 0,057 Fatigue load limit

Pu/P 0,449

ηcPu/P 0,135


L10mh(B)=106/(60*n)*L10m 8600 SKF rating life, operating hours

Table 29: Rating Life

THIRD CONDITION (limit value): Rating life is calculated varying speed and temperature (RPMlimit=36000 rpm and Tlimit=160°C). In Table 36 are reported the calculation of the rating life (L10 and L10h) and the SKF rating life. The SKF rating life, operating hours is 2800h, accelerated ageing conditions: 9x required to access 25800hours.




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inlet value_limit value (RPM and T)



n, rpm 36000 speed

T, °C 160

grease

ASONIC HQ 72-

102

viscosity, mm2/s

100 (40°C)

12 (100°C)



results


C/P 27,2 Load ratio

L10=(C/P)^3 20124 Basic rating life (at 90% relaibility), million revolutions


v1,mm2/s 6

rated viscosity of lubrificant, depends on bearing mean

diameter and rotational speed, ref.diagram


2/s, ref

diagram


ηc 0,1 factor for contamination level, "high cleanliness", sealed

bearing :ηc=0,8


Pu,kN 0,057

Pu/P 0,449

ηcPu/P 0,045


L10mh(C)=106/(60*n)*L10m 2795 SKF rating life, operating hours

Table 30: Rating Life in extreme conditions

FOURTH CONDITION (higher dynamic load): Rating life is calculated varying speed and temperature (20%overRPM=31200 rpm and 20%overT=132°C) and increasing the axial load (effect mainly due to a high backpressure in the circuit). In Table 37 are reported the calculation of the rating life (L10 and L10h) and the SKF rating life. The SKF rating life is reduced to 1465h, accelerated ageing conditions: 18x required to access 25800hours.




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inlet value_20%overRPM_20%overT and higher load



n, rpm 31200 speed

T, °C 132


viscosity, mm2/s

100 (40°C)

12 (100°C)



results


C/P 21 Load ratio


revolutions


v1,mm2/s 6

rated viscosity of lubrificant, depends on bearing

mean diameter and rotational speed, ref.diagram


2/s,

ref diagram


ηc 0,1 factor for contamination level, "high cleanliness",

sealed bearing :ηc=0,8


Pu,kN 0,057

Pu/P 0,345

ηcPu/P 0,035


L10mh(C)=106/(60*n)*L10m 1465 SKF rating life, operating hours

Table 31: Rating Life with a higher axial load




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In order to analyze a correct rating life, the operating conditions, such as the magnitude and direction of loads, speeds, temperatures and lubrication conditions are continually changing. Within each duty interval, the bearing load and operating conditions can be averaged to some constant value. The number of operating hours or revolutions expected from each duty interval showing the life fraction required by that particular load condition should also be included. Under variable operating conditions, bearing life can be rated using this formula: �10� � 1/�1/�10�1 2/�10�2 3/�10�3�


equivalent

dynamic

load , P

SKF rating

life, L10mh

time

fraction,U

resulting

SKF rating

life, L10mh

1 132 31200 0,127 8600 0,2

2277 2 160 36000 0,127 2800 0,4

3 132 31200 0,165 1465 0,4


AIR BLOWER FIRST STANDARD CONDITION: Rating life in standard conditions is calculated starting from the bearings characteristics.

Table 33: Blower bearings characteristics (Domel data)

In Table 12 are reported the calculation of the rating life (L10 and L10h) and in particular is introduced the askf manufacturer life modification factor according to ISO 281. It depends on lubrification conditions (ηc, Pu, k).

The SKF rating life, operating hours are 29240h (NMB 608) and 48000 (NMB 629). The bearing limiting is NMB 608, the following accounts will be made only on this bearing and they will be normalized to 20000h operational.




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inlet value_standard condition (608 bearing)



n, rpm 20000 speed

T, °C 70

grease Y551

viscosity, mm2/s

47,8 (40°C)

8 (100°C)



results


C/P 26 Load ratio



v1,mm2/s 8




2/s, ref

diagram



bearing :ηc=0,8


Pu,kN 0,057

Pu/P 0,45

ηcPu/P 0,27


L10mh(A)=106/(60*n)*L10m 29240 SKF rating life, operating hours

Table 34: Rating Life in standard conditions (NMB 608)




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inlet value_standard condition (629 bearing)



n, rpm 20000 speed

T, °C 70

grease Y695H

viscosity, mm2/s

47,8 (40°C)

8 (100°C)



results


C/P 31 Load ratio



v1,mm2/s 8




2/s, ref

diagram



bearing :ηc=0,8


Pu,kN 0,08

Pu/P 0,53

ηcPu/P 0,32


L10mh(A)=106/(60*n)*L10m 48067 SKF rating life, operating hours

Table 35: Rating Life in standard conditions (NMB 629) SECOND CONDITION: Rating life is calculated varying speed and temperature (20%overRPM=24000 rpm and 20%overT=84°C). The SKF rating life, operating hours is 6660h, accelerated ageing conditions: 3x required to access 20000hours. THIRD CONDITION (limit value): Rating life is calculated varying speed and temperature (RPMlimit=36000 rpm and Tlimit=110°C). The SKF rating life, operating hours is 2220h, accelerated ageing conditions: 9x required to access 20000hours. FOURTH CONDITION (higher dynamic load): Rating life is calculated varying speed and temperature (20%overRPM=24000 rpm and 20%overT=84°C) and increasing the axial load (effect mainly due to a high backpressure in the circuit). The SKF rating life is reduced to 870h, accelerated ageing conditions: 23x required to access 20000hours.




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In order to analyze a correct rating life, the operating conditions, such as the magnitude and direction of loads, speeds, temperatures and lubrication conditions are continually changing

Duty

interval T,°C RPM

equivalent

dynamic

load , P

SKF

rating

life,

L10mh

time fraction,U

resulting

SKF rating

life, L10mh

1 84 24000 0,127 6660 0,2

1493 2 110 36000 0,127 2220 0,4

3 84 24000 4.04 870 0,4


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