24.10.2017 moses workshop sion christoph gentner
TRANSCRIPT
125.10.2017
24.10.2017– MOSES Workshop Sion
Christoph Gentner
A HT-PEM fuel cell system model for the
electric power supply on ships
225.10.2017
motivation
reduction of emissions
dieselgenerator(500 kW)
fuel cell system(2 x 5 kW)
state of the art- diesel electric ships
alternative- unconventional fuels
and energyconverter
- since 2012 HT-PEM
challenge- reduction of
emissions
source picture: Topaz – M. Fischbach; C18 – www.cat.com; H3 5000 Rack – www.serenergy.com
325.10.2017
HT-PEM fuel cell system
known characteristics
fuel mix: S/C = 1,5
system efficiency
load acceptance
???
source picture: H3 5000 – www.serenergy.com, source efficiency: e4ships Brennstoffzellen im maritimen Einsatz 2009 – 2016 (2016)pilot plant: METHANOL POWERED FUEL CELL SYSTEMS FOR MARINE APPLICATIONS, C. Thiem, C. Gentner & G. Ackermann; SCC 2015
object of investigation
HT-PEM with water-methanol fuel mix
developed for TELCO industry
nominal power output: 5 kW el, DC
0.3
0.35
0.4
0.45
0.5
1 1.5 1.75 2 2.5 3 3.5 4 4.5 5
η
electric power output in kW
module efficiency
425.10.2017
measurements
setupa) reactor with fluegas heat
exchangerb) evaporator with oil inlet and
exhaustgas pipec) heated oil tankd) heated measuring pipee) MFCs for air and hydrogenf) solid state relaisg) Labview compact rio
525.10.2017
fuel cell system module- anode gas: synthesis gas (H2 + CO2 + H2O)- Methanol steam reforming in processing unit
called: reformer- stack waste heat recovery: fuel mix
evaporation
HT-PEM
FCS module and reformer
reformer- catalytic burner: burns anode off gas- reactor: CH3OH + H2O 3 H2 + CO2- evaporator uses waste heat from: stack,
fluegas & synthesis gas
cathodeexhaust
reformerexhaust
aircoolantfeedair
stackreformer &evaporator
catalyticburner
reactor
Fuel mixevaporator
625.10.2017
physical model
reformer
Processunit
controlvolumes• every element has its own mass, connecting areas,
conductivity and specific heat. ሶ𝜗𝐶𝑉• elements (fluid & solid) are coupled by heat transition
and conduction
discretization in flow direction• 2 sections catalytic burner• 5 sections reformer• 5 sections evaporator
first principle of thermodynamics
d𝐸
d𝑡= ሶ𝑄 = ሶ𝜗𝐶𝑉 ⋅ 𝑚𝐶𝑉 ⋅ 𝑐𝑝,𝐶𝑉
ሶ𝑚𝐹𝑒𝑒𝑑,(𝑔)
ሶ𝑚𝐹𝑙𝑢𝑒𝑔𝑎𝑠
ሶ𝑚𝑆𝑦𝑛𝑔𝑎𝑠
(2)
(3)
(4)𝜗𝑊𝑎𝑙𝑙𝑘
𝜗𝑊𝑎𝑙𝑙𝑘+1
𝜗𝑇𝑜𝑝,𝑙𝑘
𝜗𝑆𝑦𝑛𝑔𝑎𝑠𝑘
𝜗𝑇𝑜𝑝,𝑐𝑘
𝜗𝑇𝑜𝑝,𝑟𝑘
725.10.2017
model calibration
syngas rector in
syngas reactor out
syngas reformer out
time in seconds
fluegasrector in
fluegas rector out
fluegas reformer out
oil tank
oil evaporator in
oil evaporator out
ϑ in
°C
measurements
simulation
feed flow
parameter estimation- minimisation of the quadratic difference to measurements- simple geometry: identical geometric data in every section- time intense iterative procedure: ~ 100 Parameters to guess- direct feedback to the user: e.g. heat conduction in aluminum housing
825.10.2017
physical model
bipolar plate
first principle of thermodynamics
air oil synthesisgas
boundary condition𝜗𝑙𝑒𝑓𝑡 = 𝜗𝑟𝑖𝑔ℎ𝑡
bipolar plate ~ 3 mm
not modelled:membrane
thermal model
bipolar plate- 1 plate represents the stackmassflows are scaled- simple geometry: identical geometric data in every section (total 5)- not validated with measurements- geometry known, pyhsical properties from literature
d𝐸
d𝑡= ሶ𝑄 = ሶ𝜗𝐶𝑉 ⋅ 𝑚𝐶𝑉 ⋅ 𝑐𝑝,𝐶𝑉
925.10.2017
reformer control• 𝜆𝐻2-stack changes in
order to supply heat fora constant reactortemperature
feedflow
• 𝜆𝑂2-reactor follows themeasurements
airflow
HT-PEM model
aircoolantfeedair
stack control• electric power is a
control objective stack current
• 𝜆𝑂2-stack is constant cathode airflow
• oil mass flow iscontrolled to keep stacktemperature constant
oilmassflow
fuel cell system model- reformer- stack (5300 W)- auxiliaries (300 W)- control
Meyer-Werft measurements
power curvepolarization curves
1025.10.2017
simulation results
FCSM characteristics
characteristics- waste heat in cooling water and exhaustgas- fuel cell stack produces water- exhaustgas cooling recovers water (25 °C & 40 °C)
steam reforming
combustion
cooling water wh exhaust gas wh H2O overproduction
el. power FCSM in kW SM H2O > 0:self supply possible
1125.10.2017
FCSM results
• exhaustgas composition(humid air and CO2)
• waste heat use:(for seawater evaporation)
• efficiency(> 40 %)
simulation results:
• air demand(similar DG)
fuel supply
methanolbunker
water:recycle/ evaporate
new pol. curve (S 1), degraded (S 2)
1225.10.2017
energy simulation
system simulation- Input: measurements general consumers- Fuel cell system model with load dynamics- Transients loads for battery storage- Controlled variable: state of charge
1325.10.2017
single line diagram a- FCS independent (directional energy flow)- BS independent (bidirectional energy flow)- controlled SOC
integration
single line diagram b- FCS charges the battery storage- integrated system (unidirectional energy flow)- Controlled SOC
battery storage: Bs
fuel cell system: Bza
1425.10.2017
sizing of a battery storage
worst case scenario- load shedding (La3)- FCS ramps down- SOC increases (start: 60 %)
legend------------------------La1: 95 % 75 %La2: 95 % 50 %La4: 95 % 10 %------------------------
battery: 161 kWhC-Rate < 1------------------------
general consumer
fuel cell system
state of charge (battery)
1525.10.2017
energy simulation results
measured 12 dayScenario: ~ 1,5 MW
high speed diesel generator fuel cell system
specific mass 9 kg/kW 19 kg/kW (incl. battery)
specific volume 14 … 20 l/kW 20 l/kW
CO2 100 % 83 %
conclusion- FCS reduce air pollutants (humid air + CO2, low noise, no vibrations )- energy storage necessary- comparable size and volume to medium speed dieselgenerator- expensive
1625.10.2017
thank you for yourattention!
M. Sc. Christoph GentnerTUHH Institut M-4
Elektrische Energiesysteme und Automation
1725.10.2017
simulation results
FCSM characteristics
characteristics- from simulation extracted data for steady states- S1/S2 different operating modes- S1/S3 new degradated polarization curve OK efficiency match
el. power FCSM in kW
efficiency CH3OH consumption
air demand CO2 production exhaustgas temperature
1825.10.2017
energy simulation
load following mode or SOC boundary- FCS can follow the load in 80 % of all cases no significant change of SOC (high frequency switching: load - unload) SOC always at setpoint of 60 % (good to survive crtical load cases)- FCS can operate highly decoupled from load (Alternative II)
mode forcriticaloperations
mode foruncriticaloperations
1925.10.2017
fuel cell systems vs
dieselgeneratorors (10.2017)
MSL SL PEM (H2) HT-PEM (CH3OH)
mass / power17
kg
kWel,AC9
kg
kWel,AC10
kg
kWel,DC12…15
kg
kWel,DC
volume / power
27 … 37l
kWel,AC14 … 20
l
kWel,AC14
l
kWel,DC17
l
kWel,DC
fuelconsumption
205g
kWh225
g
kWh72
g
kWh440
g
kWh
price280 …400
€
kWel,AC5000
€
kWel,DC5000
€
kWel,DC
electricenergy price
0,06€
kWhAC0,10
€
kWhAC0,68
€
kWhDC0,15
€
kWhDC
HFO = 294 €/t; MGO = 428 €/t; H2 = 9500 €/tCH3OH = 330€/t
2025.10.2017
Methodology
Measurements + Simulation
pilot plant (2 x 5 kW) AC operation exhaustgasanalysis waste heat potential
limited load change(8 %/min & 17 %/min)
methanol reformer- dynamics (syngas output: vane anemometer)- temperatures (fluids & body)- FC-stack waste heat (𝜗-controlled)- catalytic burner (controlled MFCs H2 & air)- synthesis gas composition
using gas chromatography
pilot plant: METHANOL POWERED FUEL CELL SYSTEMS FOR MARINE APPLICATIONS, C. Thiem, C. Gentner & G. Ackermann; SCC 2015
2125.10.2017
simulation results
new vs degraded
2225.10.2017
steady state measurements
analysis of synthesis gas composition• H2 using a thermal conductivity sensor (WLD)• H2 using gas chromatography (GC)• CO2 … (GC)• CO … (GC)• CH3OH: condensate head space
analysis (GC)
ሶ𝑚𝐹𝑒𝑒𝑑 𝑥𝐶𝐻3𝑂𝐻𝑀𝑒𝑎𝑠𝑢𝑟𝑒 𝑥𝐶𝐻3𝑂𝐻
𝐶𝑎𝑙𝑐
stoichiometric results: (Xi)
reformer
burner
2325.10.2017
Theoretical considerations
Steam to carbon ratio
𝑆
𝐶=
𝑛𝐻2𝑂𝑛𝐶𝐻3𝑂𝐻
𝑛𝑀𝑖𝑥 = 𝑛𝐻2𝑂 + 𝑛𝐶𝐻3𝑂𝐻
𝑥𝐶𝐻3𝑂𝐻 =𝑛𝐶𝐻3𝑂𝐻
𝑛𝐻2𝑂 + 𝑛𝐶𝐻3𝑂𝐻
The fuel mix (feed) consists of 60 vol.-% methanol and40 vol.-% water (S/C = 1,5).Is it the optimum?
How do the equilibrium states look like?Minimize the Gibbs energy.
Methanex 2006
2425.10.2017
Theoretical considerations
Steam to carbon ratio
substance amount fraction
𝑥𝑖 =𝑛𝑖σ𝑛𝑖
CO2CO
CH3OH H2O H2
X-axis: temperature in °CY-axis: S/C ratio
objective S/C temperature
H2 ↑ ~ 1 150 °C
CO ↓ high low
CH3OH ↓ high High
η ↑ High small
2525.10.2017
Theoretical considerations
Steam to carbon ratio
CO2CO
CH3OH H2O H2
X-axis: temperature in °CY-axis: S/C ratio
η
S/C = 1,5 (60 % CH3OH)OK!ϑ = 150 °C … 250 °C
2625.10.2017
Measurements
Sankey Diagram (Load = 100 %)
ሶ𝐻𝑂𝑢𝑡ሶ𝑄𝐼𝑛
=2,71
3,35 + 1,25= 59%
ሶ𝑄𝐿𝑜𝑠𝑠ሶ𝑄𝐼𝑛
=0,14
3,35 + 1,25= 3%
ሶ𝑄𝑊𝐻
ሶ𝑄𝐼𝑛=
0,75
3,35 + 1,25= 16 %
ሶ𝑄𝐶𝑜𝑛𝑑ሶ𝐻𝐸𝑣𝑎
=0,54
2,26 + 0,28= 21 %
combustion
exhaust heat loss
oil
feed
𝚫𝐑𝑯synthesis gas (Xi)standard state
cooling & condensation
2725.10.2017
Measurements
Dynamic behaviour
time in seconds time in seconds
mas
sflo
win
g/s
reasons for high order system with dead time• film flow evaporation causes timedelay• higher order due to series connection of
control volumes:1. evaporator2. superheater3. reactor4. heat exchanger
No hydrogen discontinuities are detected for changing feed flow!
insulated temperature controlled measuringsection with vane anemometer
Feed
Simulation
Measurement
2825.10.2017
Projekt Schiff Bz-Technologie Leistung / kW
Brennstoff
1985 ff.Studie
Vindicator MCFC 4 x 625 MDO
2003 ff.Demo.
Viking Lady MCFC 320 LNG
2006 ff.Demo.
Undine SOFC 20 CH3OH
2006 ff.Demo.
Alsterwasser PEM 50 H2O
Stand der Wissenschaft
Brennstoffzellen auf Schiffen
ab 2009 folgen: Rivercell, E4Ships, E4Ships 2 und viele weitere- Pa-X-ell (HT-PEM mit Methanol + Wasser) - ShiBZ (SOFC mit Diesel)
Vorangegangene Forschungsprojekte
2925.10.2017
HT-PEM Modellierung
• Massenbilanz: Reaktorumsatz -> Polarisationskurve
• Energiebilanz: Fluid- & Festkörpertemperaturen
3025.10.2017
Metrological investigation
Steady State Measurements
fluegas synthesis gas
feed in kg/hfeed in kg/h feed in kg/h
oil
3125.10.2017
Systembeschreibung
H3 5000