GT-140002

January 2014

Delivery efficiency of the Jaga Low H2O heat

exchanger in a Tempo enclosure

Determination of the delivery efficiency for a quality declaration for the ISSO database

GT-140002

January 2014

Delivery efficiency of the Jaga Low H2O heat

exchanger in a Tempo enclosure

© 2014 Kiwa N.V. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, whether electronic, mechanical, photocopying, recording, or in any other way, without the prior written permission of the publisher.

Kiwa Technology B.V.

Wilmersdorf 50

Postbus 137

7300 AC Apeldoorn

Tel. 055 539 33 93

Fax 055 539 34 94

www.kiwatechnology.nl

Determination of the delivery efficiency for a quality declaration for the ISSO database

Colophon

Title Delivery efficiency of the Jaga Low H2O

heat exchanger in a Tempo enclosure Project number 130901030 Project manager ir. M.J. Kippers Client Jaga-Konvektco Nederland B.V.

J. Verdonck Quality assurer(s) ir. J.C. de Laat Author(s) ing. E.F.J. Fennema, ir. M.J. Kippers

This report is not public and is only provided to the clients of the contract research project/consulting project. Any further distribution will be by the client itself.

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Summary

Jaga-Konvektco has developed the Low H2O heat exchanger, which provides energy

savings compared to a standard radiator. Jaga likes to use this energy saving as a

selling point. Jaga intends to have the Low H2O heat exchanger included in the

database that is linked to the energy performance standard (EPN) by means of a

quality certificate. The energy savings of the Low H2O heat exchanger are therefore

also included in the energy performance coefficient calculation. The database with

quality declarations is managed by ISSO (knowledge institute for the installation

sector.)

Using simulations, which are based on national and international standards, and

measurements performed by Jaga-Konvektco, Kiwa Technology has calculated the

energy savings of the Low H2O heat exchanger. The energy savings of the Low H2O

heat exchanger are at least 5%.

The quality declaration for the Low H2O heat exchanger in a Tempo enclosure is set

out in the annex.

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Contents

Summary 1

1 Introduction 3

1.1 Background 3

1.2 Jaga Low H2O heat exchanger with Tempo type 15 enclosure 3

1.3 Task: Calculation of the delivery efficiency of the Low H2O heat exchanger 4

1.4 Report layout 5

2 The Low H2O heat exchanger is more energy efficient than standard radiators 6

2.1 Result is at least 5% energy saving 6

2.2 The delivery efficiency is determined using an annual simulation of the Low H2O heat exchanger in a standard home 7

2.2.1 The simulation is modular 7 2.2.2 Modelling of the Jaga Low H2O 7

Literature list 9

I Calculation of the delivery efficiency 10

II Modelling of the Jaga Low H2O heat exchanger 11

III Quality declaration: delivery efficiency 'lH,em of Jaga Low H2O heat exchanger in a Tempo enclosure 16

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1 Introduction

1.1 Background

The energy performance of a building depends, among other things, on the efficiency

of the delivery system. These delivery systems include the radiators. The energy

performance is calculated on the basis of the "Energy performance standard for

buildings" (EPG, NEN7120).

As standard the EPG assumes default values for the delivery efficiency of delivery

systems under various conditions. However, the standard also offers the alternative to

evaluate the delivery efficiency through a quality declaration. The quality declaration

has the advantage that a distinction can be made between different delivery systems

based on their efficiency. Innovative energy-efficient delivery systems can therefore

make a positive contribution to the calculated energy performance of a building and in

this way are competitive. ISSO (knowledge institute for the installation sector)

assesses the validity of quality declarations and manages the "verified quality

declaration database".

1.2 Jaga Low H2O changer combined with Tempo type 15 enclosure

The Jaga Low H2O Tempo is a heat emission system based on a heat exchanger in

an enclosure as shown in figure 1, 2 and 3.

Figure 1: Jaga Low H2O heat exchanger Figure 2: Jaga enclosure Tempo type 15

NEN 7120 "Energy performance standard for buildings" (EPG)

- based on the European Energy Performance Buildings Directive (EPBD)

The efficiency of delivery systems using default values (standard route)

all delivery systems have the same efficiency

no possibility for evaluating innovative energy-efficient delivery

systems

default values included in NEN 7120

The efficiency of delivery system based on quality declaration

(alternative route)

distinguish between delivery systems in terms of efficiency

recognition for innovative energy-efficient delivery

systems

quality declaration included in the ISSO "verified quality

declaration database"

quality declaration issued by Kiwa

Energy performance of the building

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Figure 3: Jaga Low H2O heat exchanger in Tempo plus type 15 (wall mounted model)

The Low H2O heat exchanger is made of copper tubes and corrugated aluminium

fins. The serial matrix-flow channels (Figure 1) ensure a good heat transfer of central

heating-water to the air. Due to the compact design, the Low H2O heat exchanger

contains relatively little water and steel parts. Thus, the exchanger reacts fast to a

heat demand and does not heat up unnecessarily when the optimum indoor

temperature is reached. The heat exchanger is mounted at the bottom of the

enclosure. Since the beginning of 2014, the Jaga Tempo type 15 conversion has an

insulating layer on the wall side to limit the loss of energy to the outside.

The Jaga exchanger differs from a conventional radiator in the way described below,

which is relevant for the EN7120:

Advantages:

o The surface of the heat exchanger is significantly smaller than a

conventional radiator. This leads to less radiation loss through the

back wall.

o The insulating layer in the enclosure on the wall side limits the

energy losses to the back wall.

o Significantly smaller heat capacity results in a faster response

time for heat output during a 'cold start'.

Disadvantages:

o The lower temperature and smaller surface results in a smaller

radiation component in the Fanger comfort equation.

o The convection losses to the back wall are higher because there

is a bigger air flow along the back wall.

1.3 Task: Calculation of the delivery efficiency of the Low H2O heat

exchanger Jaga-Konvektco has commissioned Kiwa Technology to calculate the delivery

efficiency of the Low H2O heat exchanger mounted in a type 15 Tempo enclosure.

Kiwa Technology has developed a simulation model for this exchanger. The

simulation model is based on an existing model that was also used for an earlier

quality declaration of a delivery system. Use is also made of the existing model of the

reference radiator from the previous project. The simulations were then carried out

for the purposes of the quality declaration. Furthermore, Kiwa Technology

supervises the process for the ISSO request.

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1.4 Report layout In the following chapter the realisation of the calculated delivery efficiencies is

presented as well as the annual simulation of the radiators in a standard house. The

quality declaration is included within the annex.

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2 The Low H2O heat exchanger is

more energy efficient than standard radiators

The delivery efficiency of the Low H2O heat exchanger is higher than the delivery

efficiency of standard radiators. This is the result of a year’s simulation of both

radiators in a standard home. The energy performance of a building is, to a large

extent, determined by the required energy for space heating. The delivery efficiency

together with the generation and distribution efficiency determines the overall

efficiency of the heating system. The delivery efficiency has an influence in the

determination of the EPC of a building. A more efficient radiator therefore gives a

better EPC rating of the building.

In this chapter the calculated delivery efficiencies are presented as well as the

annual simulation of the radiators in a standard house.

2.1 Result is at least a 5% energy saving

Table 1 shows the calculated delivery efficiency of the Low H2O heat exchanger

{riH,calc,LH2O) and the calculated delivery efficiency of the standard radiator type 22

{riH,calc,std). The reference delivery efficiency of the standard radiator (riH,ref,std) from

EN7120 [Lit 1] is also shown.

The reference delivery efficiency for the Low H2O heat exchanger (riH,ref,LH2O) is the

calculated delivery efficiency (riH,calc,LH2O) of the competitor product ECO radiator

scaled with the relationship between the calculated delivery efficiency (riH,calc,std) and

reference delivery efficiency (riH,ref,LH2O) of the standard radiator, see annex I: This is

the efficiency that is included in the quality declaration.

Simulations were carried out for low and high average delivery temperatures and for

newbuild and existing buildings. The simulations are based on standard tests from

the standard for energy performance of buildings [Lit 4].

Table 1: Delivery efficiency of the Low H2O standard heat exchanger calculated with the annual simulation

Average delivery temperature: ≤50° C Average delivery temperature: >50° C

STD radiator Low H2O STD radiator Low H2O

Test riH,calc,std

[-]

riH,ref,std

[-]

riH,calc,LH2O

[-]

'lH,ref,LH2O

[-]

riH,calc,std

[-]

riH,ref,std

[-]

riH,calc,LH2O

[-]

'lH,ref,LH2O

[-]

Newbuild 0.89 1.00 0.98 1.10 0.91 0.95 0.99 1.03

Existing building 0.80 0.95 0.93 1.11 0.86 0.90 0.97 1.01

The annual simulations show that the calculated delivery efficiency of the Low H2O

heat exchanger is higher than the calculated delivery efficiency of standard radiators.

The Low H2O heat exchanger achieves at least a 5% energy saving compared with a

standard radiator. The delivery efficiency is averaged and is rounded down to 0.05 in

accordance with EN7120 [Lit 1]. The delivery efficiency is summarised in the quality

declarations in annex III, where a maximum value of 1.00 is used as agreed with

ISSO.

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2.2 The delivery efficiency is determined using an annual simulation of the Low H2O heat exchanger in a standard house Kiwa Technology has proven the energy saving of the Low H2O heat exchanger with

the help of the software package Matlab/Simulink. A standard home was simulated

[Lit 1] containing a standard parallel radiator or a Low H2O heat exchanger.

In Chapter 2.2.1 there is a description of the general simulation model. Then in

chapter 2.2.2 the Low H2O heat exchanger model is described which is contained

within.

2.2.1 The simulation is modular

The modular structure of the model is shown schematically in Figure 4. It consists of

three levels.

Figure 4: Structure of the simulation model to determine the performance of the Low H2O standard heat exchanger and standard radiator

At the top level external conditions are configured, including internal heat, heat

emission, ventilation, climate and sun, these are then presented to the subsystems

'building subsystem' and 'radiator subsystem'. The second level concerns the

'building subsystem'. This subsystem contains the model of a standard room and is

based on EN7120 [Lit 1]. The third level contains a detailed simulation of a standard

or a Low H2O heat exchanger. The theoretical model of the Low H2O heat exchanger

is validated on the basis of a practical measurement by Jaga-Konvekto according to

EN442, [Lit 6]. The complete model is validated according to EN15265 [Lit 4] by

calculating a number of cases, in which a standard radiator is used.

2.2.2 Modelling of the Jaga Low H2O

The Jaga Low H2O heat exchanger with the associated heat transfer mechanisms, is

shown in figure 5. In the middle of the figure there is the heat exchanger, including

enclosure and insulation, seen mounted on the wall. The heat exchanger radiates to

the enclosure and the insulation on the wall. The warm air carries heat to the enclosure

and the insulation on the wall by forced convection. The wall carries heat to the outside

air by radiation and free convection. The enclosure also carries heat to the air in the

room by radiation and free convection. The heat transfer at the wall and enclosure are

magnified on the sides.

Thermostat Sun Climate Ventilation Heat emission Internal heat

Radiator subsystem LH2O or standard

Simulation (verified according to EN15265 with standard radiator)

Building subsystem

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Figure 5: Jaga Low H2O heat exchanger with heat transfer mechanisms

The elaboration of this model is shown in annex II.

Insulation

Wall

Enclosure

Heat exchanger

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Literature list

Lit 1 NEN 7120:2011, Energy performance of buildings – Determination method

Lit 2 NEN-EN 15316-2-1:2007, Heating systems in buildings - method of calculating the energy requirement and the system efficiency - Part 2-1: Delivery systems for space heating

Lit 3 NEN-EN-ISO 13790:2008, Energy performance of buildings - Calculation of energy use for space heating and cooling

Lit 4 NEN-EN 15265:2007, Energy performance of buildings - Calculation of energy needs for space heating and cooling using dynamic methods - General criteria and validation procedures

Lit 5 NEN-EN-ISO 6946:1997, Components and elements of buildings – thermal resistance and thermal transmittance – determination method (ISO 6946:1996)

Lit 6 NEN-EN 442-2:1996, Radiators and convectors - test methods and presentation of the performance

Lit 7 polytechnic notebook G1/9, 48th

Edition, Royal PBNA, 1998)

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I Calculation of the delivery efficiency

The delivery efficiency is the ratio between the heat demand and the heat delivered to

the house:

QH;nd

riH QH;em

With

riH

QH;nd

QH;em

the delivery efficiency [-]

the heat demand [MJ]

the supplied heat [MJ]

The calculated delivery efficiency (riH,calc,LH2O) of the Low H2O heat exchanger is

scaled based on a reference delivery efficiency for the Low H2O heat exchanger

{riH,LH2O) with the relationship between the calculated delivery efficiency (riH,calc,std) and

reference delivery efficiency (riH,ref,std) of the standard radiator:

H , LH 2O H ,ref ,std

riH ,calc,LH 2O

riH ,calc,std

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II Modelling of the Jaga Low H2O heat exchanger

The Jaga Low H2O heat exchanger with the associated heat transfer mechanisms, is

shown in Figure 5. In Figure 6 the Jaga Low H2O heat exchanger is shown in a lumped

capacitance scheme.

Figure 6: Lumped capacitance scheme of the Jaga Low H2O heat exchanger

This scheme consists of five known parameters and 20 unknown parameters, see Table

2. The 20 unknown parameters are to be solved using the equations from Table 2

that in are worked out in Table 3.

Known parameters Unknown parameters Comparison

T exchanger T air T outside T room Q in

T inside wall T outside wall T enclosure inside T enclosure outside T air out Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10

Q11

Heat transfer Q1 Heat transfer Q2 Heat transfer Q3 Heat transfer Q4 Heat transfer Q5 Heat transfer Q6 Heat transfer Q7 Heat transfer Q8 Heat transfer Q9 Heat transfer Q10

Law of conservation of energy (thermal pull) Law conservation of energy (system limits) Energy balance node A

Energy balance node B Energy balance node C Energy balance node D

T exchanger

Radiation (Q5)

T outside Conduction (Q2)

T wall inside

Convection (Q7) T air

T enclosure inside

T enclosure outside

Radiation (Q1)

Conduction (Q8)

Air which is flowing out on the top of the enclosure (Q11) T air out

T room

Radiation (Q9)

Radiation (Q3)

Convection (Q10)

Convection (Q4) Convection (Q6)

T wall outside

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Q12 Energy balance node E

Q13 Energy balance node F

Q14 Energy balance node G

Q15 Energy balance node H

Table 2: Model parameters and equations

Q1 Radiation from the exchanger to the enclosure

The radiation is calculated by: Q =A·F·L·f3·(T 4-T 4)

rad exch wall

with

A = [m2] surface (top of the exchanger) F = [-] view factor L = [-] emission factor f3 = 5.67·10-8 [W/(m2·K4)] Boltzmann constant Texch = [K] temperature of the exchanger Twall = [K] temperature of the wall

Q2 conduction through the wall

The heat transfer is calculated using the equation for heat transfer by conduction.

Q = k/l·A·T [W] heat transfer

k = [W/(m·K)] thermal conductivity coefficient l = [m] wall thickness

A = [m2] area of the wall above the exchanger within the enclosure

T = Twall inside -Twall outside [K]

Q3 Radiation from the outer wall to the outside

See equations Q1

Q4 Convection from the outer wall to the outside

The heat transfer is calculated using the equation for heat transfer by free convection along a vertical wall.

Q = h·A·T [W] heat transfer

h = Nux·k/l [W/(m2·K)]

A = [m2] surface of the wall

T = Twall outside -Toutside[K] Nux = 0.671*(Pr/(Pr+0.986·Pr(1/2)+0.492))(1/4)·Ra(1/4)

Ra = (g·f3)/(a·v) ·l3T [-] Rayleigh number (g·f3)/(a·v) = air property

Q5 Radiation of the exchanger to the enclosure

See equations Q1

Q6 Convection to the inner wall

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1

2

3

The heat transfer is calculated using the equation for heat transfer by forced internal convection.

Q = h·A·T [W] heat transfer

h = NuD·k/Dh [W/(m2·K)] A = [m

2] area of the wall above the exchanger within the enclosure

T = Tair-Twall[K] k = [W/(m·K)] thermal conductivity coefficient Dh = 4·A/p [m] hydraulic diameter (A = surface; p = perimeter)

3 3 3 (1/3)

NuD = (Nu1 +0.7 +(Nu2-0.7) ) Nu1 = 3.66

Nu2 = 1.615·(ReDh·Pr·Dh/l)(1/3)

ReDh = vi·Dh,i/v [-] Reynolds number v = [m

2/s] kinematic viscosity of air

Pr = 0,72 [-] Prandtl number

Q7 Convection to the enclosure (inside)

See equations Q6

Q8 Conduction by the enclosure

See equations Q2

Q9 Radiation from the enclosure to the room

See equations Q1

Q10 Convection from the enclosure to the room

See equations Q4

Law conservation of energy (thermal pull (as part of convection))

The thermal pull (flow rate of air) is calculated using the law of conservation of energy and the law of conservation of mass.

P = P1 + P2 + P3 + P4 + P5 = (·g·l [Pa]] (law of conservation of energy)

p5

P1 =

(1·0.5··v 2

[Pa] pressure loss at entry of the exchanger

P2 = (2·l/Dh

wis·0,5··v 2

[Pa] pressure loss between the lamella of the exchanger

P3 =

(3·0,5··v 2

[Pa] pressure loss at transition from the exchanger to the enclosure

p4

P5 = (5·0,5··v5

4

[Pa] pressure loss in the enclosure

p3

P5 = (5·0,5··v5

[Pa] pressure loss at exit of the enclosure p2

v5

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= v4·= v3·= v2·= v1·m/s] (law of conservation of mass)

with

g = 9.81 [m/s2] gravitational acceleration

l = [m] height of the lamella

= [kg/m3] density of air

vi = [m/s] air speed (1 = 1 [-] friction factor

(2 = 4·24/ReDh [-] friction factor

p1

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(3 = 1 [-] friction factor (4 = 4·24/ReDh [-] friction factor (5 = 1 [-] friction factor Dh = 4*A/p [m] hydraulic diameter (A = surface; p = perimeter) ReDh = vi·Dh,i/v [-] Reynolds number v = [m2/s] kinematic viscosity of air

The heat transfer is calculated using the equation for heat transfer by forced convection.

Q = ·A·T [W]

heat transfer with = 0.664·Pr1/3·Re1/2 [W/(m2·K)] Nusselt number A = [m2] projected surface of the exchanger on the wall Pr = 0,72 [-] Prandtl number

Law conservation of energy (system limits)

Qin=Q12+Q13=Q14+Q15+Q11

Energy balance node A

Q12=Q1+Q5

Energy balance node B

Q1+Q6=Q2

Energy balance node C

Q2=Q3+Q4

Energy balance node D

Q3+Q4=Q14

Energy balance node E

Q13=Q6+Q7+Q11

Energy balance node F

Q5+Q7=Q8

Energy balance node G

Q8=Q9+Q10

Energy balance node H

Q9+Q10=Q15

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III Quality declaration: delivery efficiency 'lH,em of Jaga Low H2O heat

exchanger in a Tempo enclosure

Individual heating or district heating with individual metering. Height in computation

zone space of up to 8m.

Heat delivery type of heating system Average delivery

temperature

≤50ºC >50ºC

2a) Radiator heating and/or convector heating for outside

wall d; average thermal resistance of the external partition

elements e at the location of the radiators or convectors, Rc in

m2K/W, equal to or larger than 2.5

1.00

1.00

2b) Radiator heating and/or convector heating for outside

wall d; average thermal resistance of the external partition

elements e at the location of the radiators or convectors, Rc in

m2K/W, less than 2.5

1.00

1.00

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