SIST EN ISO 22975-2:2017

SLOVENSKI STANDARD
SIST EN ISO 22975-2:2017
01-januar-2017
6RQþQDHQHUJLMD6HVWDYQLGHOLLQPDWHULDOLVSUHMHPQLNRYVRQþQHHQHUJLMHGHO
9DNXXPVNLFHYQLVLVWHPKHDWSLSH]DXSRUDERVRQþQHWRSORWH7UDMQRVWLQ
]PRJOMLYRVW,62
Solar energy - Collector components and materials - Part 2: Heat-pipes for solar thermal
application - Durability and performance (ISO 22975-2:2016)
Solarenergie - Kollektorbauteile und -materialien - Teil 2: Wärmerohre für
solarthermische Anwendungen - Beständigkeit und Leistungsfähigkeit (ISO 22975-
2:2016)
Energie solaire - Composants et matériaux du collecteur - Partie 2: Caloduc pour
application thermique solaire - Durabilité et performance (ISO 22975-2:2016)
Ta slovenski standard je istoveten z: EN ISO 22975-2:2016
ICS:
27.160 6RQþQDHQHUJLMD Solar energy engineering
SIST EN ISO 22975-2:2017 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 22975-2:2017

---------------------- Page: 2 ----------------------

SIST EN ISO 22975-2:2017


EN ISO 22975-2
EUROPEAN STANDARD

NORME EUROPÉENNE

October 2016
EUROPÄISCHE NORM
ICS 27.160
English Version

Solar energy - Collector components and materials - Part 2:
Heat-pipes for solar thermal application - Durability and
performance (ISO 22975-2:2016)
Énergie solaire - Composants et matériaux du Solarenergie - Kollektorbauteile und -materialien - Teil
collecteur - Partie 2: Caloduc pour application 2: Wärmerohre für solarthermische Anwendungen -
thermique solaire - Durabilité et performance (ISO Beständigkeit und Leistungsfähigkeit (ISO 22975-
22975-2:2016) 2:2016)
This European Standard was approved by CEN on 12 September 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 22975-2:2016 E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 22975-2:2017
EN ISO 22975-2:2016 (E)
Contents Page
European foreword . 3

2

---------------------- Page: 4 ----------------------

SIST EN ISO 22975-2:2017
EN ISO 22975-2:2016 (E)
European foreword
This document (EN ISO 22975-2:2016) has been prepared by Technical Committee ISO/TC 180 "Solar
energy" in collaboration with Technical Committee CEN/TC 312 “Thermal solar systems and
components” the secretariat of which is held by ELOT.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2017, and conflicting national standards shall be
withdrawn at the latest by April 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 22975-2:2016 has been approved by CEN as EN ISO 22975-2:2016 without any
modification.

3

---------------------- Page: 5 ----------------------

SIST EN ISO 22975-2:2017

---------------------- Page: 6 ----------------------

SIST EN ISO 22975-2:2017
INTERNATIONAL ISO
STANDARD 22975-2
First edition
2016-10-01
Solar energy — Collector components
and materials —
Part 2:
Heat-pipes for solar thermal
application — Durability and
performance
Énergie solaire — Composants et matériaux du collecteur —
Partie 2: Caloduc pour application thermique solaire — Durabilité et
performance
Reference number
ISO 22975-2:2016(E)
©
ISO 2016

---------------------- Page: 7 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

---------------------- Page: 8 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test overview . 2
5 Durability . 3
5.1 High temperature resistance test . 3
5.1.1 Objective . . 3
5.1.2 Test conditions. 3
5.1.3 Apparatus . 3
5.1.4 Procedure . 3
5.1.5 Results . 3
5.2 Freeze resistance test . 4
5.2.1 Objective . . 4
5.2.2 Test conditions. 4
5.2.3 Apparatus . 4
5.2.4 Procedure . 4
5.2.5 Results . 5
6 Performance . 5
6.1 Starting temperature of heat-pipes . 5
6.1.1 Principle . 5
6.1.2 Test conditions. 5
6.1.3 Apparatus . 5
6.1.4 Procedure . 5
6.1.5 Results . 6
6.2 Temperature uniformity of heat-pipes . 6
6.2.1 Principle . 6
6.2.2 Test conditions. 6
6.2.3 Apparatus . 6
6.2.4 Procedure . 6
6.2.5 Results . 7
6.3 Heat transfer power of heat-pipes . 7
6.3.1 Principle . 7
6.3.2 Test conditions. 7
6.3.3 Apparatus . 8
6.3.4 Procedure .10
6.3.5 Results .11
Annex A (informative) Typical configuration of a heat-pipe for solar thermal application .12
Annex B (normative) Test reports on a heat-pipe for solar thermal application .13
Bibliography .22
© ISO 2016 – All rights reserved iii

---------------------- Page: 9 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 180, Solar energy.
ISO 22975 consists of the following parts, under the general title Solar energy — Collector components
and materials:
— Part 1: Evacuated tube — Durability and performance
— Part 2: Heat-pipes for solar thermal application — Durability and performance
— Part 3: Absorber surface durability
The following parts are under preparation:
— Part 5: Insulation material durability and performance
iv © ISO 2016 – All rights reserved

---------------------- Page: 10 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

Introduction
This part of ISO 22975 specifies test methods for durability and performance of heat-pipes for solar
thermal application.
This part of ISO 22975 is applicable to all heat-pipes for use with both evacuated tubes and flat plate
collectors.
For each durability and performance test, its objective, principle, test condition, apparatus, procedure
and test results are specified.
For all the tests specified in this part of ISO 22975, a complete heat-pipe is required.
© ISO 2016 – All rights reserved v

---------------------- Page: 11 ----------------------

SIST EN ISO 22975-2:2017

---------------------- Page: 12 ----------------------

SIST EN ISO 22975-2:2017
INTERNATIONAL STANDARD ISO 22975-2:2016(E)
Solar energy — Collector components and materials —
Part 2:
Heat-pipes for solar thermal application — Durability and
performance
1 Scope
This part of ISO 22975 specifies definitions and test methods for durability and performance of heat-
pipes for solar thermal application.
This part of ISO 22975 is applicable to heat-pipes for use with evacuated tubes, including glass-metal
sealed evacuated tubes and double-glass evacuated tubes, as well as with flat plate collectors.
This part of ISO 22975 provides test methods for determining durability of the heat-pipe, including high
temperature resistance and freeze resistance.
This part of ISO 22975 also provides test methods for measuring performance of the heat-pipe, including
starting temperature, temperature uniformity and heat transfer power of the heat-pipe.
This part of ISO 22975 is only applicable to gravity heat-pipes.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 9488, Solar energy — Vocabulary
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9488 and the following apply.
3.1
heat-pipe
heat transfer element, utilizing latent heat of phase-change for heat transfer
3.2
gravity heat-pipe
heat-pipe (3.1) without a capillary wick inside, in which the liquefied working fluid (3.6) returns from
condenser (3.4) to evaporator (3.3) due to its own weight
3.3
evaporator
part of a heat-pipe (3.1), where the liquefied working fluid (3.6) absorbs heat, vaporizes and becomes the
vaporized working fluid
© ISO 2016 – All rights reserved 1

---------------------- Page: 13 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

3.4
condenser
part of a heat-pipe (3.1), where the vaporized working fluid (3.6) releases heat, condenses and becomes
the liquefied working fluid
3.5
adiabatic section
part of a heat-pipe (3.1), located between evaporator (3.3) and condenser (3.4), where working fluid (3.6)
has minimal heat exchange with the surroundings
3.6
working fluid
medium used for heat transfer in a heat-pipe (3.1)
3.7
tilt angle (of heat-pipe)
angle between the horizontal plane and a heat-pipe (3.1)
3.8
starting temperature of heat-pipe
minimum temperature required for a heat-pipe (3.1) to start operating
3.9
temperature uniformity of heat-pipe
temperature difference between evaporator (3.3) and condenser (3.4) when a heat-pipe (3.1) operates
under normal conditions
3.10
heat transfer power of heat-pipe
thermal power transferred to the cooling liquid from a heat-pipe (3.1) when using the cooling liquid to
remove heat
3.11
stable conditions
conditions in performance tests of a heat-pipe (3.1), in which the temperature variation is less than ±1 K
over a period depending on the performance test item
4 Test overview
Durability tests and performance tests for heat-pipes are specified in Clause 5 and Clause 6, respectively.
The tests shall be performed in the sequence according to Table 1.
All these tests shall be performed on the same heat-pipes.
Table 1 — Test list
Clause Test
5.1 High temperature resistance test
a
5.2 Freeze resistance test
6.1 Starting temperature of heat-pipes
6.2 Temperature uniformity of heat-pipes
b
6.3 Heat transfer power of heat-pipes
a
The freeze resistance test shall be carried out only for heat-pipes claimed to be freeze resistant.
b
The heat transfer power test shall be performed after the high temperature resistance test.
2 © ISO 2016 – All rights reserved

---------------------- Page: 14 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

5 Durability
5.1 High temperature resistance test
5.1.1 Objective
This test is intended to assess the capability of a heat-pipe to withstand high temperature without
failure.
5.1.2 Test conditions
The test shall be carried out under the following conditions:
a) test environment: indoors;
b) ambient temperature: 15 °C to 35 °C;
c) test temperature in heating chamber: 180 °C ± 5 °C or 230 °C ± 5 °C or 280 °C ± 5 °C depending on
specific application and manufacturer’s declaration;
d) tilt angle of heat-pipe: 90° ± 1°.
The test may be conducted at any higher heating chamber temperature, if requested.
5.1.3 Apparatus
The test apparatus consists of a heating chamber and a thermometric system.
Measuring instruments shall meet the following requirements:
a) heating chamber temperature controller, with an accuracy of ±0,5 K;
b) ambient temperature sensor; standard uncertainty shall not be more than ±0,5 K;
c) digital clock/data acquisition system; standard uncertainty shall not be more than ±10 s/d.
5.1.4 Procedure
The test shall be carried out for a batch of at least 10 sample heat-pipes of the same product.
The procedure shall be as follows.
a) Place all sample heat-pipes into the heating chamber at the specified tilt angle.
b) Increase the temperature in the heating chamber slowly (maximum 20 K/min) up to the selected
test temperature.
c) Maintain the test temperature for 30 h.
d) After the heat-pipes have cooled to room temperature, visually inspect for damage, such as leakage,
breakage, distortion or deformation.
5.1.5 Results
The product will be qualified if there is no visual evidence of damage to the heat-pipes.
Results of the inspection shall be reported together with ambient temperature, test temperature in
heating chamber and test duration.
© ISO 2016 – All rights reserved 3

---------------------- Page: 15 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

5.2 Freeze resistance test
5.2.1 Objective
This test is intended to assess the extent to which a heat-pipe, which is claimed to be freeze resistant,
can withstand freezing.
5.2.2 Test conditions
The test shall be carried out under the following conditions:
a) test environment: indoors;
b) ambient temperature: 20 °C to 30 °C;
c) freezing temperature: −20 °C ± 1 °C;
d) thawing temperature: 20 °C ± 1 °C;
e) tilt angle of heat-pipe: 90° ± 1°.
5.2.3 Apparatus
The test apparatus consists of an appropriate freezing device and a thawing device.
Measuring instruments shall meet the following requirements:
a) temperature controllers used for the freezing device and thawing device, with an accuracy of ±0,5 K;
b) surface temperature sensor; standard uncertainty shall not be more than ±0,5 K;
c) ambient temperature sensor; standard uncertainty shall not be more than ±0,5 K;
d) digital clock/data acquisition system; standard uncertainty shall not be more than ±10 s/d.
5.2.4 Procedure
The test shall be carried out for a batch of at least 10 sample heat-pipes of the same product.
The procedure shall be as follows.
a) Place all sample heat-pipes into the freezing device at the specified freezing temperature for
60 min, at the specified tilt angle.
b) Remove samples from freezing device, and within 30 s, insert them into the thawing device at the
specified thawing temperature, keeping the evaporator in lower position, to a depth not less than
1/9 of the total length of the heat-pipe.
c) After heat-pipes are inserted into the thawing device, measure and record the temperature on the
condenser surface at a point between 18 mm and 22 mm from top of the condenser. Wait for 5 min
after the temperature difference between the thawing device and the condenser surface is not
larger than 9 K.
NOTE If the temperature difference falls below 9 K, this indicates that the heat-pipe has started to
operate again.
d) Repeat Steps a) to c) 20 times.
e) After the heat-pipes have been removed from the thawing device, visually inspect for damage, such
as leakage, breakage, distortion or deformation.
4 © ISO 2016 – All rights reserved

---------------------- Page: 16 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

5.2.5 Results
The product will be qualified if there is no visual evidence of damage to the heat-pipes.
Results of the inspection shall be reported together with ambient temperature, freezing temperature,
thawing temperature, tilt angle of the heat-pipe, insertion depth in thawing device, as well as number of
freeze-thaw cycles.
6 Performance
6.1 Starting temperature of heat-pipes
6.1.1 Principle
This test is intended to determine the minimum temperature required for a heat-pipe to start operating.
6.1.2 Test conditions
The test shall meet the following conditions:
a) test environment: indoors;
b) ambient temperature: 15 °C to 20 °C;
c) cold water bath temperature: 10 °C ± 0,5 °C;
d) hot water bath temperature: 25 °C ± 0,5 °C or 30 °C ± 0,5 °C or 40 °C ± 0,5 °C, depending on specific
application for different working temperature of the heat-pipe, and 40 °C ± 0,5 °C is the maximum
test temperature;
e) tilt angle of the heat-pipe: 90° ± 1°.
6.1.3 Apparatus
Two thermostatic water baths are used for the test. The cold water bath is maintained at the specified
cold water bath temperature, and the hot water bath is maintained at the selected hot water bath
temperature.
Measuring instruments shall meet the following requirements:
a) temperature controllers used for the cold water bath and hot water bath, with an accuracy ±0,5 K;
b) temperature sensors used for measuring surface and ambient temperature; standard uncertainty
shall not be more than ±0,5 K;
c) digital clock/data acquisition system; standard uncertainty shall not be more than ±10 s/d.
6.1.4 Procedure
The procedure shall be as follows.
a) Fit a surface temperature sensor to the condenser of the heat-pipe, at a point between 18 mm and
22 mm from top of the condenser. Thermally insulate the heat-pipe, except for 1/6 of its length at
the evaporator end.
b) Immerse the lower end of the heat pipe in the cold water bath to a depth of 1/6 of the total length
of the heat-pipe, at the specified tilt angle. Wait for at least 3 min after stable conditions have been
reached.
© ISO 2016 – All rights reserved 5

---------------------- Page: 17 ----------------------

SIST EN ISO 22975-2:2017
ISO 22975-2:2016(E)

c) Remove the heat pipe from the cold water bath and immerse its lower end in the hot water bath to a
depth of 1/6 of the total length of the heat-pipe, at the specified tilt angle.
d) Measure and record the temperature on the condenser surface every 10 s until at least 120 s after
stable conditions have been reached.
6.1.5 Results
The condenser surface temperature of the heat-pipe shall be recorded.
The results of the measurement shall be reported together with ambient temperature, cold water bath
temperature, hot water bath temperature, insertion depth of the heat-pipe, distance of measuring point
from top of condenser and variation of condenser surface temperature.
6.2 Temperature uniformity of heat-pipes
6.2.1 Principle
This test is intended to measure the temperature difference between evaporator and condenser when a
heat-pipe operates under normal conditions.
6.2.2 Test conditions
The test shall meet following conditions:
a) test environment: indoors;
b) ambient temperature: 25 °C ± 5 °C;
c) test temperature in hot water bath: 90 °C ± 0,5 °C;
d) tilt angle of heat-pipe: 90° ± 1°.
6.2.3 Apparatus
A thermostatic hot water bath is used for the test, maintained at the specified test temperature.
Measuring instruments shall meet the following requirements:
a) temperature controller used for the hot water bath, with an accuracy ±0,5 K;
b) temperature sensors used for measuring ambient, surface and hot water temperature; standard
uncertainty shall not be more than ±0,5 K;
c) digital clock/data acquisition system; standard uncertainty shall not be more than ±10 s/d.
6.2.4 Procedure
The procedure shall be as follows.
a) Fit a surface temperature sensor to the condenser of the heat-pipe, at a point between 18 mm and
22 mm from top of the condenser.
b) Insert the heat-pipe into the water of the thermostatic hot water ba
...