IEC TS 62610-3:2009

Mechanical structures for electronic equipment - Thermal management for cabinets in accordance with IEC 60297 and IEC 60917 series - Part 3: Design guide: Evaluation method for thermoelectrical cooling systems (Peltier effect)

IEC/TS 62610-3:2009(E) provides an evaluation method for thermoelectrical cooling systems (Peltier effect). With this design guide it is possible to calculate the efficiency of the thermoelectrical cooling system (Peltier effect) and its cooling power depending on the ambient temperature and internal temperature. This design guide can also be used to appraise thermoelectrical cooling systems by its efficiency.

General Information

• Status: Published
• Publication Date: 13-Dec-2009
• ICS: 31.240 - Mechanical structures for electronic equipment
• Technical Committee: SC 48D - Mechanical structures for electrical and electronic equipment
• Drafting Committee: WG 5 - TC 48/SC 48D/WG 5
• Current Stage: PPUB - Publication issued
• Start Date: 14-Dec-2009
• Completion Date: 31-Jan-2010

Standards Content (Sample)

IEC/TS 62610-3 ®
Edition 1.0 2009-12
TECHNICAL
SPECIFICATION
colour
inside
Mechanical structures for electronic equipment – Thermal management for
cabinets in accordance with IEC 60297 and IEC 60917 series –
Part 3: Design guide: Evaluation method for thermoelectrical cooling systems
(Peltier effect)
IEC/TS 62610-3:2009(E)
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IEC/TS 62610-3 ®
Edition 1.0 2009-12
TECHNICAL
SPECIFICATION
colour
inside
Mechanical structures for electronic equipment – Thermal management for
cabinets in accordance with IEC 60297 and IEC 60917 series –
Part 3: Design guide: Evaluation method for thermoelectrical cooling systems
(Peltier effect)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 31.240 ISBN 978-2-88910-773-5
– 2 – TS 62610-3 © IEC:2009(E)
CONTENTS
FOREWORD.0H3
INTRODUCTION.1H5
1 Scope and object.2H6
2 Normative references .3H6
3 Abbreviations, symbols and indices .4H6
3.1 Abbreviations .5H6
3.2 Symbols .6H7
3.3 Indices .7H7
4 Theory of the thermoelectrical cooling system .8H7
4.1 The Peltier element .9H7
4.2 Thermoelectrical cooling systems.10H8
5 Measurement setup .11H12
6 Interpretation and evaluation .12H13
Annex A (informative) Sample calculation .13H17
Bibliography.14H30

Figure 1 – Principles of the thermoelectrical cooling system .15H9
Figure 2 – Thermal resistances.16H10
Figure 3 – Thermodynamic system boundaries of a thermoelectrical cooling system
attached to a closed cabinet .17H11
Figure 4 – Measurement setup.18H12
Figure 5 – Results of the measurement.19H14
Figure 6 – Example for a specification sheet of a thermoelectrical cooling system
(Peltier) .20H16
Figure A.1 – Mollier h-x-diagram for humid air .21H20
Figure A.2 – Principles of the Peltier effect .22H21
Figure A.3 – Illustration for Z dependent on the number of charge carrier .23H22
Figure A.4 – Influence of the Figure of Merit ZT on the efficiency of the Peltier device.24H22
Figure A.5 – Thermodynamic system boundaries of a Peltier device .25H23
Figure A.6– Thermal resistance of a thermoelectrical cooling system.26H24
Figure A.7 – Typical temperature curve of a thermoelectrical cooling system .27H25
Figure A.8 – Example for the thermal resistance between air and a heat sink as a
function of the air velocity .28H26
Figure A.9 – Temperature distribution of a common heat sink for given boundary
29H26
conditions .
Figure A.10 – Illustration of the importance of the Thermal Interface Material (TIM).30H27
Figure A.11 – Dependency of the effective cooling power Q on the difference ΔT
C
between inside temperature and ambient temperature .31H28

Table A.1 – Measurement dataset.32H17

TS 62610-3 © IEC:2009(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MECHANICAL STRUCTURES FOR ELECTRONIC EQUIPMENT –
THERMAL MANAGEMENT FOR CABINETS IN ACCORDANCE
WITH IEC 60297 AND IEC 60917 SERIES –

Part 3: Design guide: Evaluation method
for thermoelectrical cooling systems (Peltier effect)

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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6) All users should ensure that they have the latest edition of this publication.
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a technical
specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• The subject is still under technical development or where, for any other reason, there is
the future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.

– 4 – TS 62610-3 © IEC:2009(E)
IEC 62610-3, which is a technical specification, has been prepared by subcommittee 48D:
Mechanical structures for electronic equipment, of IEC technical committee 48:
Electromechanical components and mechanical structures for electronic equipment.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
48D/401/DTS 48D/414/RVC
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62610 series can be found, under the general title Mechanical
structures for electronic equipment – Thermal management for cabinets in accordance with
IEC 60297 and IEC 60917 series, on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
TS 62610-3 © IEC:2009(E) – 5 –
INTRODUCTION
Besides the conventional compressor cooling there are several alternatives for cooling, for
example: absorption cooling, thermoelectric cooling (Peltier), magneto caloric cooling, CO
cooling and others.
For the design of thermoelectrical cooling systems, values of the dissipation loss depending
on the ambient temperature and internal temperature are necessary.
Thermoelectrical cooling systems performance is a function of ambient temperature, hot and
cold side heat exchanger (heat sink) performance, thermal load, of the design of the Peltier
device and of Peltier electrical parameters.
Therefore an evaluation method has to be developed. This design guide allows a comparison
of thermoelectrical cooling systems.

– 6 – TS 62610-3 © IEC:2009(E)
MECHANICAL STRUCTURES FOR ELECTRONIC EQUIPMENT –
THERMAL MANAGEMENT FOR CABINETS IN ACCORDANCE
WITH IEC 60297 AND IEC 60917 SERIES –

Part 3: Design guide: Evaluation method
for thermoelectrical cooling systems (Peltier effect)

1 Scope and object
This part of IEC 62610 provides an evaluation method for thermoelectrical cooling systems
(Peltier effect).With this design guide it is possible to calculate the efficiency of the
thermoelectrical cooling system (Peltier effect) and its cooling power depending on the
ambient temperature and internal temperature. This design guide can also be used to
appraise thermoelectrical cooling systems by its efficiency.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 62194:2005, Method of evaluating the thermal performance of enclosures
3 Abbreviations, symbols and indices
For the purposes of this document, the following abbreviations, symbols and indices apply.
3.1 Abbreviations
COP coefficient of performance [-]
c heat capacity [W/kgK]
P
D pipe diameter [m]
I current [A]
k overall heat transfer coefficient k [W/ m K]
n total number of Peltier devices [-]
Δp pressures difference [Pa]
Q energy flow (thermal, electrical, conductivity) [W]
Q effective cooling power of the thermoelectrical cooling system (Peltier) [W]
C
Q cooling power of a Peltier device at operating conditions [W]
cPe
Q total dissipated heat flow on the hot side [W]
D
Q heating power inside the cabinet [W]
H
R electrical resistance of the Peltier device [V/A]
Pe
R thermal resistance [K/W]
i
S surface [m ]
T temperature [K]
V voltage [V]
TS 62610-3 © IEC:2009(E) – 7 –
&
V volume flow [m /s]
ZT Figure of Merit [-]
3.2 Symbols
α Seebeck coefficient [V/K]
ρ density [kg/m³]
λ thermal conductivity [W/m K]
σ electrical conductivity [S/m = A/V]
ϕ relative humidity
3.3 Indices
1-7 position marks
A related to an air flow
a ambient
C effective cooling power
c cold side
D total dissipated and removed heat on the hot side
E electrical power applied to the thermoelectrical cooling system
F Fan
H heating inside the cabinet
h hotside
i internal, inside the cabinet
L heat loss
m average
Pe related to the Peltier device
R reverse
S related to the whole thermoelectrical cooling system
4 Theory of the thermoelectrical cooling system
4.1 The Peltier element
The Peltier effect is the direct conversion of electric voltage to temperature differences and
the reverse process is called Seebeck effect.
Therefore a thermoelectrical cooling system (Peltier effect) transfers heat from one side of the
device to the other side against the temperature gradient, with consumption of electrical
energy.
This Peltier effect is described by the following equation:
⎛ ⎞
1 λ ⋅S
2 Pe Pe
⎜ ⎟() []
Q = α ⋅I⋅T − ⋅I ⋅R − ⋅ T − T W [1]
cPe c Pe 4h 4c
⎜ ⎟
2 x
⎝ Pe ⎠
The cooling power of one Peltier element Q depends on different phenomena.
cPe
– 8 – TS 62610-3 © IEC:2009(E)
The term α ⋅I ⋅ T is the maximum cooling power based on the Peltier effect, whereas α
c
represents the Seebeck coefficient.
1 ⎛ λ ⋅ A ⎞
2 Pe Pe
⎜ ⎟
The term ⋅I ⋅R represents the Joule heating, the term ⋅()T − T is the
Pe 4 4
h c
⎜ ⎟
2 x
Pe
⎝ ⎠
heat conduction between the hot and the cold side through the Peltier element.
According to Equation 1 it is a requirement to minimize the terms of the Joule heating and the
heat conduction.
For the evaluation of a Peltier element the coefficient Figure of Merit ZT was defined as
shown in Equation 2.
α ⋅ σ
ZT= ⋅ T [−] [2]
λ
which represents the ratio between the electrical conduction σ to the heat conduction λ at a
given temperature T.
ZT is therefore a very convenient figure for comparing the potential efficiency of devices using
different materials. Values of ZT=1 are considered good, and values of at least the 1–3 range
are considered to be essential for thermoelectrics to compete with mechanical generation and
refrigeration in efficiency.
4.2 Thermoelectrical cooling systems
The thermoelectrical cooling systems (see Figure 1) transport heat Q from one medium to
c
another whereas these media can be either gas or liquid. For a better heat transfer, heat
sinks are connected to each side of the Peltier device. The material between the Peltier
device and the heat sink is called Thermal Interface Material (TIM).

TS 62610-3 © IEC:2009(E) – 9 –

cold side
hot side
Peltier device
TIM
heat sink
fluid
T
Detail A:
x
T T T T T T
1 2 3 5 6 7
T T
4h 4c
Q
R
Detail A:
insulation
T
Q
cPe
Q
E
x
x
T PE T
3 5
T T
4h 4c
IEC  2351/09
Figure 1 – Principles of the thermoelectrical cooling system

– 10 – TS 62610-3 © IEC:2009(E)
The medium at temperature T passes the heat sink of the thermoelectrical cooling system
(Peltier) which has a temperature of T and is cooled by convection. The heat is transferred
through the heat sink by conduction at the given temperature gradient between T and T .
6 5
Then the heat flux is transferred through the Thermal Interface Material (TIM) by conduction.
The Peltier device is responsible for the main temperature gradient.
On the hot side of the Peltier device the heat flux passes the TIM and the heat sink due to
conduction and finally the heat is removed by the medium on the hot side by convection.
The total thermal resistance limiting the total heat flux is a sum of every resistance of each
described process (see Figure 2).

medium I      heat sink      TIM      Pe.      TIM       heat sink     medium II
Q Q
D                                C
T T T T T T T T
1 2 3 4H 4K 5 6 7
hot side cold side
IEC  2352/09
Figure 2 – Thermal resistances
The thermal resistances can be expressed as followed:
T − T
T − T
5 4K
2 1
R = []K / W R = []K / W
1 5
Q Q
D C
T − T T − T
3 2 6 5
R = []K / W  R = []K / W
2 6
Q
Q
C
D
T − T T − T
4H 3 7 6
R = []K / W R = []K / W
3 7
Q Q
D C
R = R [3]
total ∑ i
i=1
Minimizing each resistance is necessary for designing an efficient thermoelectrical cooling
system.
As shown in 33HFigure 1 the empty space between the two heat sinks and the Peltier devices is
filled with insulation materials to avoid a reverse heat flux Q from the hot heat sink to the
R
cold one due to conduction. For an efficient working thermoelectrical cooling system this
reverse heat flux through the insulation is to be minimized at all costs. Therefore in further
calculation this heat flow Q is assumed to be zero.
R
TS 62610-3 © IEC:2009(E) – 11 –
III
I
ϕ T
1 A,1
ϕ T
4 A,4
Q Q IV
D
C
Q
R
ϕ T ϕ T
3 A,3 2 A,2
Q
E
Q
L
II
Q
H
IEC  2353/09
Figure 3 – Thermodynamic system boundaries of a thermoelectrical
cooling system attached to a closed cabinet
The power equations for each thermodynamic system according to 34HFigure 3 are as followed:
I: Q = Q − Q + Q ± (Q = 0) [4]
C H L F,c R
II: Q = Q + Q + Q ± (Q = 0) [5]
D C E F,h R
&
III: Q = V ⋅ρ ⋅c ⋅()T − T [6]
C c p A,1 A,2
&
IV: Q = V ⋅ρ ⋅c ⋅()T − T [7]
D h p A,4 A,3
Q = k ⋅S ⋅()T − T [8]
L i,m a,m
The heat flux Q which is removed from the cabinet is the heating power Q minus the heat
C H
over the cabinet walls. Q is the heat dissipation from the fan on the cold side and is
loss Q
L F,c
a function of the efficiency factor of the fan and its rotation speed. The power balances
according system boundary II indicates that the heat flux Q is the sum of Q and the power
D C
Q that is applied to the Peltier devices and the dissipated heat from the fan on the hot side
E
Q minus the reverse heat flux Q through the insulation.
F,h R
Furthermore it is assumed that no condensation of water vapour occurs while cooling. This
implies that the relative humidity ϕ which is dependent on system temperature and on system
pressure has to fulfil certain conditions.

– 12 – TS 62610-3 © IEC:2009(E)
The relative humidity is defined by the ratio between the partial pressure of water vapour in
the mixture p and the saturated vapour pressure of water at the given temperature of the
H O
*
mixturep .
H O
p
H O
ϕ = ⋅100% [9]
*
p
H O
With disregard of the so-called supersaturated state, water vapour condensation occurs at ϕ =
100 %. Therefore it shall be ensured that there is no condensation of water vapour during the
cooling.
5 Measurement setup
35HFigure 4 shows the general measurement setup for the evaluation of a thermoelectrical
cooling system. It consists of a cabinet that is surrounded by a climate room to keep the
ambient temperature constant. In the cabinet a heater is placed to simulate the heat
dissipation under operating conditions. The thermoelectrical cooling system (Peltier) is
mounted onto the cabinet. It has to be considered that there is no short-circuit of the airflows.

climate room
ϕ T
4, A,4
p
ϕ T
1, A,1
cabinet
V
c
U
F,c
I
F,c V
c
U
Pe
I
Pe
ϕ T
3, A,3
ϕ T
2 A,2
V
h
p
U U
F,h H
I I
F,h H
IEC  2354/09
Figure 4 – Measurement setup
TS 62610-3 © IEC:2009(E) – 13 –
The power inlet for the heater, fans and the Peltier devices as well as the ambient
temperature shall be independently adjustable for measuring at fixed conditions. The airflow
can be easily determined by using a measuring nozzle with defined diameter as shown in
36HFigure 4. By measuring the pressures difference the air velocity w in m/s in the pipe can be
calculated with the following equation.
2 p
⋅ Δ
w = ε ⋅ τ ⋅ [m/ s] [10]
ρ
with ε ≈ 1 (compression factor) and τ ≈ 1 (value of resistance of the nozzle) for air, the
pre
...