Thermal solar systems and components - Custom built systems - Part 4: Performance test methods for solar combistores

This European Standard specifies test methods for the performance characterization of stores which are intended for use in small custom built systems as specified in EN 12977-1.
Stores tested according to this document are commonly used in solar combisystems. However, the thermal performance of all other thermal stores with water as a storage medium (e.g. for heat pump systems) can be also assessed according to the test methods specified in this document.
This document applies to combistores with a nominal volume up to 3 000 l and without integrated burner.
NOTE   This document is extensively based on references to EN 12977-3:2012.

Thermische Solaranlagen und ihre Bauteile - Kundenspezifisch gefertigte Anlagen - Teil 4: Leistungsprüfung von Warmwasserspeichern für Solaranlagen zur Trinkwassererwärmung und Raumheizung (Kombispeicher)

Diese Europäische Norm legt Prüfverfahren für die Beschreibung der Leistung von Speichern fest, die zur Verwendung in kleinen kundenspezifisch gefertigten Solaranlagen nach EN 12977-1:2018 bestimmt sind.
Die nach diesem Dokument geprüften Speicher werden häufig in solaren Kombianlagen eingesetzt. Jedoch kann auch die thermische Leistung aller anderen Wärmespeicher, bei denen Wasser als Speichermedium zum Einsatz kommt (z. B. Wärmepumpenanlagen), nach den in diesem Dokument festgelegten Prüfverfahren bewertet werden.
Dieses Dokument gilt für Kombispeicher mit einem Nennvolumen von bis zu 3 000 l und ohne integrierten Brenner.
ANMERKUNG Das vorliegende Dokument nimmt umfassend Bezug auf EN 12977-3:2018.

Installations solaires thermiques et leurs composants - Installations assemblées à façon - Partie 4 : Méthodes d'essai des performances pour chauffe-eau solaires et installations solaires combinées

La présente Norme européenne spécifie des méthodes d’essai pour la caractérisation des performances des dispositifs de stockage destinés à être utilisés dans de petites installations assemblées à façon, comme indiqué dans l’EN 12977-1:2018.
Les dispositifs de stockage soumis à essai conformément au présent document sont couramment utilisés dans les installations solaires combinées. Cependant, la performance thermique de tous les autres dispositifs de stockage thermiques utilisant de l’eau comme support de stockage (par exemple pour des installations de pompe à chaleur) peut également être évaluée conformément aux méthodes d’essai spécifiées dans le présent document.
Le présent document s’applique aux dispositifs de stockage combinés ayant un volume nominal jusqu’à 3000 litres et sans brûleur intégré.
NOTE Le présent document est principalement basé sur les références de l’EN 12977-3:2018.

Toplotni sončni sistemi in sestavni deli - Neserijsko izdelani sistemi - 4. del: Preskusne metode delovanja sončnih zbiralnikov

Ta evropski standard določa preskusne metode za delovanje hranilnikov, ki so namenjeni za uporabo v majhnih neserijsko izdelanih sistemih v skladu s standardom EN 12977-1.
Hranilniki, ki se preskušajo v skladu s tem dokumentom, se običajno uporabljajo v sončnih kombiniranih sistemih. Vendar se lahko na podlagi preskusnih metod iz tega dokumenta oceni tudi toplotna učinkovitost vseh drugih hranilnikov toplote, ki kot sredstvo shranjevanja uporabljajo vodo (npr. za sisteme toplotnih črpalk).
Ta dokument se uporablja za kombinirane hranilnike z nazivno prostornino do 3000 l in brez vgrajenega gorilnika.
OPOMBA:   Ta dokument v veliki meri temelji na sklicih na standard EN 12977-3:2012.

General Information

Status
Published
Public Enquiry End Date
19-Sep-2017
Publication Date
20-Aug-2018
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
20-Apr-2018
Due Date
25-Jun-2018
Completion Date
21-Aug-2018

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Thermische Solaranlagen und ihre Bauteile - Kundenspezifisch gefertigte Anlagen - Teil 4: Leistungsprüfung von Warmwasserspeichern für Solaranlagen zur Trinkwassererwärmung und Raumheizung (Kombispeicher)Installations solaires thermiques et leurs composants - Installations assemblées à façon - Partie 4 : Méthodes d'essai des performances pour chauffe-eau solaires et installations solaires combinéesThermal solar systems and components - Custom built systems - Part 4: Performance test methods for solar combistores91.140.65Oprema za ogrevanje vodeWater heating equipment91.140.10Sistemi centralnega ogrevanjaCentral heating systems27.160Solar energy engineeringICS:Ta slovenski standard je istoveten z:EN 12977-4:2018SIST EN 12977-4:2018en,fr,de01-september-2018SIST EN 12977-4:2018SLOVENSKI

STANDARDSIST EN 12977-4:20121DGRPHãþD
SIST EN 12977-4:2018
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12977-4
April
t r s z ICS
t yä s x râ
{ sä s v rä s râ
{ sä s v rä x w Supersedes EN
s t { y yæ vã t r s tEnglish Version
Thermal solar systems and components æ Custom built systems æ Part

vã Performance test methods for solar combistores Installations solaires thermiques et leurs composants æInstallations assemblées à façon æ Partie

v ã Méthodes d 5essai des performances pour chauffeæeau solaires et installations solaires combinées

Thermische Solaranlagen und ihre Bauteile æ Kundenspezifisch gefertigte Anlagen æ Teil

vã Leistungsprüfung von Warmwasserspeichern für Solaranlagen zur Trinkwassererwärmung und This European Standard was approved by CEN on

t { October
t r s yä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Rue de la Science 23,
B-1040 Brussels

t r s z CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s t { y yæ vã t r s z ESIST EN 12977-4:2018

EN 12977-4:2018 (E) 2 Contents Page European foreword ....................................................................................................................................................... 4 Introduction .................................................................................................................................................................... 5 1 Scope .................................................................................................................................................................... 6 2 Normative references .................................................................................................................................... 6 3 Terms and definitions ................................................................................................................................... 6 4 Symbols and abbreviations ......................................................................................................................... 6 5 Store classification .......................................................................................................................................... 6 6 Laboratory store testing ............................................................................................................................... 7 6.1 Requirements on the testing stand ........................................................................................................... 7 6.1.1 General ................................................................................................................................................................ 7 6.1.2 Measuring data and measuring procedure ............................................................................................ 7 6.2 Installation of the store ................................................................................................................................. 7 6.2.1 Mounting ............................................................................................................................................................ 7 6.2.2 Connection ......................................................................................................................................................... 7 6.3 Test and evaluation procedures ................................................................................................................ 8 6.3.1 General ................................................................................................................................................................ 8 6.3.2 Test sequences ................................................................................................................................................. 9 6.3.3 Data processing of the test sequences .................................................................................................. 12 7 Test report ...................................................................................................................................................... 14 7.1 General ............................................................................................................................................................. 14 7.2 Description of the store ............................................................................................................................. 14 7.3 Test results ..................................................................................................................................................... 15 7.4 Parameters for the simulation ................................................................................................................ 16 Annex A (normative)

Store model benchmark tests .................................................................................... 17 Annex B (normative)

Verification of store test results ................................................................................ 18 Annex C (normative)

Benchmarks for the parameter identification ..................................................... 19 Annex D (informative)

Requirements for the numerical store model ................................................... 20 Annex E (informative)

Determination of hot water comfort ..................................................................... 21 Annex F (informative)

Implementation for Ecodesign and Energy Labelling ..................................... 22 F.1 Standing loss .................................................................................................................................................. 22 F.2 Nominal store volume ................................................................................................................................ 22 F.3 Volume of the non-solar heat storage ................................................................................................... 22 Annex ZA (informative)

Relationship between this European Standard and the energy labelling requirements of Commission Delegated Regulation (EC) No 811/2013 aimed to be covered .................................................................................................................................... 23 Annex ZB (informative)

Relationship between this European Standard and the energy labelling requirements of Commission Delegated Regulation (EC) No 812/2013 aimed to be covered .................................................................................................................................... 24 SIST EN 12977-4:2018

EN 12977-4:2018 (E) 3 Annex ZC (informative)

Relationship between this European Standard and the ecodesign requirements of Commission Regulation (EC) No 814/2013 aimed to be covered.............. 25 Bibliography ................................................................................................................................................................. 26

SIST EN 12977-4:2018

EN 12977-4:2018 (E) 4 European foreword This document (EN 12977-4:2018) has been prepared by 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 October 2018, and conflicting national standards shall be withdrawn at the latest by October 2018. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 12977-4:2012. This document has been prepared under the Mandate M/534 “Standardisation request to the European standardisation organisations pursuant to Article 10(1) of Regulation (EU) No 1025/2012 of the European Parliament and of the Council in support of implementation of Commission Regulation (EU) No 814/2013 of 2 August 2013 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for water heaters and hot water storage tanks and Commission Delegated Regulation (EU) No 812/2013 of 18 February 2013 supplementing Directive 2010/30/EU of the European Parliament and of the Council with regard to the energy labelling of water heaters, hot water storage tanks and packages of water heater and solar device” which was given to CEN by the European Commission and the European Free Trade Association. For relationship with EU Directive(s), see informative Annex ZA, ZB and ZC, which are integral parts of this document. EN 12977 is currently composed with the following parts: — Thermal solar systems and components — Custom built systems — Part 1: General requirements for solar water heaters and combisystems; — Thermal solar systems and components — Custom built systems — Part 2: Test methods for solar water heaters and combisystems; — Thermal solar systems and components — Custom built systems — Part 3: Performance test methods for solar water heater stores; — Thermal solar systems and components — Custom built systems — Part 4: Performance test methods for solar combistores; — Thermal solar systems and components — Custom built systems — Part 5: Performance test methods for control equipment. According to the CEN-CENELEC Internal Regulations, the national standards organisations 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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 12977-4:2018

EN 12977-4:2018 (E) 5 Introduction The test methods for stores of solar heating systems as described in this document are required for the determination of the thermal performance of small custom built systems for combined domestic hot water preparation and space heating, so-called solar combisystems, as specified in EN 12977-1:2018. These test methods deliver parameters, which are needed for the simulation of the thermal behaviour of a store being part of a small custom built system. NOTE 1 With the test methods for stores given in EN 12897 only a few parameters are determined in order to characterize the thermal behaviour of a store. These few parameters are not sufficient for the determination of the thermal performance of small custom built systems as described in EN 12977-2:2018. NOTE 2 The already existing test methods for stores of conventional heating systems are not sufficient with regard to solar heating systems. This is due to the fact that the performance of solar heating systems depends much more on the thermal behaviour of the store (e.g. stratification, heat losses), as conventional systems do. Hence, this separate document for the performance characterization of stores for solar heating systems is needed. NOTE 3 For additional information about the test methods for the performance characterization of stores see EN 12977-3:2018 and [1] in Bibliography. SIST EN 12977-4:2018

EN 12977-4:2018 (E) 6 1 Scope This European Standard specifies test methods for the performance characterization of stores which are intended for use in small custom built systems as specified in EN 12977-1:2018. Stores tested according to this document are commonly used in solar combisystems. However, the thermal performance of all other thermal stores with water as a storage medium (e.g. for heat pump systems) can be also assessed according to the test methods specified in this document. This document applies to combistores with a nominal volume up to 3 000 l and without integrated burner. NOTE This document is extensively based on references to EN 12977-3:2018. 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. EN 12828, Heating systems in buildings — Design for water-based heating systems EN 12977-3:2018, Thermal solar systems and components — Custom built systems — Part 3: Performance test methods for solar water heater stores EN ISO 9488:1999, Solar energy - Vocabulary (ISO 9488:1999) 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 12977-3:2018 and EN ISO 9488:1999 apply. 4 Symbols and abbreviations For the purposes of this document, the symbols and abbreviations given in EN 12977-3:2018 apply. 5 Store classification Solar combistores are classified by distinction between different charge and discharge modes. Five groups are defined as shown in Table 1. Table 1 — Classification of combistores Group Charge mode Discharge mode 1 direct direct 2 indirect direct 3 direct indirect 4 indirect indirect 5 stores that cannot be assigned to groups 1 to 4 NOTE

All stores can have one or more additional electrical auxiliary heating elements. SIST EN 12977-4:2018

EN 12977-4:2018 (E) 7 Stores that can be charged or discharged directly and indirectly (e.g. a store of a space heating system with an internal heat exchanger for the preparation of domestic hot water) can belong to more than one group. In this case, the appropriate test procedures or the assignment to one of the groups respectively, should be chosen depending on its mode of operation. 6 Laboratory store testing 6.1 Requirements on the testing stand 6.1.1 General The hot water store shall be tested separately from the whole solar system on a store-testing stand. The testing stand configuration shall be determined by the classification of the combistores as described in Clause 5. An example of a representative hydraulic testing stand configuration is shown in EN 12977-3:2018, Figure 1 and Figure 2. An appropriate test facility consists of two charge loops as shown in EN 12977-3:2018, Figure 1 and two discharge loops as shown in EN 12977-3:2018, Figure 2. 6.1.2 Measuring data and measuring procedure The requirements specified in EN 12977-3:2018, 6.1.2 shall be fulfilled. 6.2 Installation of the store 6.2.1 Mounting The store shall be mounted on the testing stand according to the manufacturer's instructions. The temperature sensors used for measuring the inlet and outlet temperatures of the fluid used for charging and discharging the storage device, shall be placed as near as possible at least 200 mm to the inlet and outlet connections of the storage device. The installation of the temperature sensors inside the pipes shall be done according to approved methods of measuring temperatures. If there is/are more than one pair of charging and/or discharging inlet or outlet connections, then only one may be connected to the testing stand (at the same time) while the other(s) shall be closed. The pipes between the store and the temperature sensors shall be insulated according to EN 12828. 6.2.2 Connection The way of connecting the storage device to the testing stand depends on the purpose of the thermal tests which shall be performed. Detailed instructions are given in the clauses where the thermal tests are described. Connections of the store which do not lead to the charge or discharge circuit of the testing stand shall be closed, and not connected heat exchangers shall be filled up with water. All closed connections shall be insulated in the same way as the store. Since fluid in closed heat exchangers expands with increasing temperature, a pressure relief valve shall be mounted. The performance of a solar heating system depends on the individual installation and actual boundary conditions. With regard to the heat losses of the store besides deficits in the thermal insulation, badly designed connections can increase the heat loss capacity rate of the store due to natural convection that occurs internally in the pipe. In order to avoid this effect, the connections of the pipes should be designed in such a way that no natural convection inside the pipe occurs. This can be achieved if the pipe is directly going downwards after leaving the store or by using a heat trap siphon. SIST EN 12977-4:2018

EN 12977-4:2018 (E) 8 6.3 Test and evaluation procedures 6.3.1 General The aim of store testing as specified in this document is to determine parameters required for the detailed description of the thermal behaviour of a combistore. Therefore, a mathematical computer model for the store is necessary. The basic requirements on suitable models are specified in Annex A and Annex B. The following parameters shall be known for the simulation of a store being part of a solar heating system. a) Stored water: 1) height; 2) effective volume respectively effective thermal capacity; 3) heights of the inlet and outlet connections; 4) heat loss capacity rate of the entire store; 5) if the insulation varies for different heights of the store, the distribution of the heat loss capacity rate should be determined for the different parts of the store; 6) a parameter describing the degradation of thermal stratification during stand-by; NOTE 1 One possible way to describe this effect in a store model is the use of a vertical thermal conduction. In this case, the corresponding parameter is an effective vertical thermal conductivity. 7) a parameter describing the characteristic of thermal stratification during direct discharge; NOTE 2 An additional parameter may be used to describe the influence of different draw-off flow rates on the thermal stratification inside the store, if this effect is relevant. 8) positions of the temperature sensors (e.g. the sensors of the collector loop and auxiliary heater control). b) Heat exchangers: 1) heights of the inlet and outlet connections; 2) volume; 3) heat transfer capacity rate as a function of temperature; 4) information on the capacity in respect of stratified charging; NOTE 3 The capacity in respect of stratified charging can be determined from the design of the heat exchanger as well as from the course in time of the heat exchanger inlet and outlet temperatures. 5) heat loss rate from the heat exchanger to the ambient (necessary only for mantled heat exchangers and external heat exchangers). SIST EN 12977-4:2018

EN 12977-4:2018 (E) 9 c) Electrical auxiliary heat source: 1) position in the store; 2) axis direction of heating element (horizontal or vertical). If the auxiliary heater is installed in a vertical way, also its length is required; 3) efficiency that characterizes the fraction of the thermal converted electric power which is actually transferred inside the store. NOTE 4 Badly designed electrical auxiliary heaters may cause significant heat losses during operation. In this case, the electrical power supplied to the heater is not equal to the thermal energy input to the store. The following clauses describe how the listed parameters can be determined. Therefore, specific test sequences are necessary. The test sequences indicated by letters (e.g. test CD) can be subdivided into phases indicated by a number (e.g. CD1 – conditioning). Between the end of one phase and the start of the following phase, a maximum stand-by time of 10 min is allowed. During this stand-by time, the ambient temperature only shall be measured and recorded. NOTE 5 One essential point of the methods described is that measurements inside the store are avoided. NOTE 6 The determination of all above listed store parameters is possible only according to the method described in 6.3.2 and the data processing of the test sequences described in 6.3.3. For further details and test sequences, see EN 12977-3:2018. 6.3.2 Test sequences 6.3.2.1 Introduction The store is tested on the test stand by different specific test sequences. The sequences are specified to simulate the physical effects, which correspond to the parameter to be determined. A parameter identification program using a store model evaluates the measuring data. Charging and discharging the entire store implies connections of the charge/discharge circuits to the uppermost and lowermost direct ports available at the hot water store. Full discharging is required for conditioning of the store and for the final discharge phase. Full charging is required for all discharge tests, which require that the entire store is charged. The series of the performed tests should comprise two tests, which include stand-by periods. One test is for the entire store, to determine the heat loss capacity rate. The other test concerns only the part of the store, which is heated up (usually the auxiliary heated part). This test is used to determine the degradation of thermal stratification during stand-by. The stand-by period should be such that the losses during this period are approximately half of the stored energy. For these two tests with stand-by periods, the same test should also be performed without a stand-by period. Flow rates and power values are given as examples only. The chosen flow rate or power should be suited to the type of component, which will be used with those connections. 6.3.2.2 General This clause describes the thermal test sequences for the different groups of combistores. This clause is based on procedures defined in EN 12977-3:2018, only new items are included. In EN 12977-3:2018 mainly the determination of the thermal capacity, heat loss capacity rate of the entire store and the heat transfer capacity rate of immersed heat exchangers is defined. The thermal test sequences described in this document shall be carried out for all groups of combistores. The storage device shall be connected to the testing stand according to 6.2. SIST EN 12977-4:2018

EN 12977-4:2018 (E) 10 6.3.2.3 General charge direct (Test CD) Test CD: — test phase CD1: conditioning until steady-state is reached; — test phase CD2: charging through test ports until ÍC,o = 55 °C; — test phase CD3:

optional stand-by until approximately half stored energy is lost to ambient; — test phase CD4: direct discharge of the entire store until steady-state is reached. Table 2 — Flow rates and store inlet temperatures for Test CD Test phase Process Charge Discharge CV ϑC,i ϑC,o DV ϑD,i ϑD,o l/h °C °C l/h °C °C CD1 conditioning 0 - - 0,5 × nV 20,0 variable CD2 charge 0,5 × nV 60,0 variable 0 - - CD3 stand-by 0 - - 0 - - CD4 discharge 0 - - 0,5 × nV 20,0 variable If the ports are used with a boiler the operating temperature of which is greater than 60 °C (e.g. a wood boiler), a higher inlet temperature (ÍC,i) may be used. 6.3.2.4 General charge indirect (Test CI) Test CI: — test phase CI1: conditioning until steady-state is reached; — test phase CI2: charge through test heat exchanger at constant power of CP = 2,0 × nP until ÍC,o = 60 °C;; — test phase CI3: optional stand-by until approximately half stored energy is lost to ambient; — test phase CI4: direct discharge of the entire store until steady-state is reached. Table 3 — Flow rates and store inlet temperatures for Test CI Test phase Process Charge Discharge CV ϑC,i ϑC,o DV ϑD,i ϑD,o l/h °C °C l/h °C °C CI1 conditioning 0 - - 0,5 × nV 20,0 variable CI2 charge 1,2 × nV variable variable 0 - - SIST EN 12977-4:2018

EN 12977-4:2018 (E) 11 CI3 stand-by 0 - - 0 - - CI4 discharge 0 - - 0,5 × nV 20,0 variable If the heat exchanger is used at different flow rates, the test should be performed four times, using, if possible, the following different charging conditions: constant power Pn at high and low flow rates, as well as constant power 0,5 × Pn at low and high flow rates. 6.3.2.5 General discharge direct (Test DD) Test DD: — test phase DD1: conditioning until steady-state is reached; — test phase DD2: charging of the entire store until ÍC,o = 55 °C; — test phase DD3: discharge through test ports until ÍD,o = 30 °C; — test phase DD4: direct discharge of the entire store until-steady-state is reached. Table 4 — Flow rates and store inlet temperatures for Test DD Test phase Process Charge Discharge CV ϑC,i ϑC,o DV ϑD,i ϑD,o l/h °C °C l/h °C °C DD1 conditioning 0 - - 0,5 × nV 20,0 variable DD2 charge 0,5 × nV 60,0 variable 0 - - DD3 discharge 0 - - 0,5 × nV 20,0 variable DD4 discharge 0 - - 0,5 × nV 20,0 variable 6.3.2.6 General discharge indirect (Test DI) Test DI: — test phase DI1: conditioning until steady-state is reached; — test phase DI2: charge of the entire store until ÍC,o = 55 °C; — test phase DI3: discharge through the test heat exchanger until ÍD,o = 30 °C; — test phase DI4: direct discharge of the entire store until steady-state is reached. SIST EN 12977-4:2018

EN 12977-4:2018 (E) 12 Table 5 — Flow rates and store inlet temperatures for Test DI Test phase Process Charge Discharge CV ϑC,i ϑC,o DV ϑD,i ϑD,o l/h °C °C l/h °C °C DI1 conditioning 0 - - 0,5 × nV 20,0 variable DI2 charge 0,5 × nV 60,0 variable 0 - - DI3 discharge 0 - - 0,5 × nV 20,0 variable DI4 discharge 0 - - 0,5 × nV 20,0 variable If the heat exchanger is intended for domestic hot water preparation, this test shall be performed three times under different discharge conditions. To each of these three discharge conditions the following two charge conditions shall apply: store fully charged and auxiliary heated part charged. In all, six tests shall be performed. The following discharge conditions should apply: — low flow rate; — high flow rate. The test shall be repeatedly performed under following conditions: Intermittent discharge at high flow rate with 10 min discharge and 10 min stand-by. This test does not need to be performed if it can be assumed that the heat transfer capacity rate of the discharge heat exchanger will not be time dependent. 6.3.3 Data processing of the test sequences 6.3.3.1 General NOTE The data processing of the test sequences is partly based on references to EN 12977-3:2018, only new items are included. The evaluation of the measured data are based on parameter identification. When all necessary tests as described in 6.3.2 are performed, identification of store parameters shall be carried out using a numerical store model that fulfils the requirements given in Annex A. For information regarding an adequate parameter identification algorithm that fulfils the necessary requirements, see EN 12977-3:2018, Annex C. The store model shall meet the requirements of the benchmark tests given in Annex A. For the parameter identification, the measured data can be compressed and/or converted to constant time steps. In both cases, the data records shall represent mean values for the corresponding time step. During charge and discharge, the time steps should not exceed 3 min. During stand-by, a maximum time step of 15 min is allowed. For the parameter identification (“fit”), the measured values of the inlet store temperatures, ambient temperature, flow rates and the power of the electrical heating source(s) shall be used as inputs. Since at the beginning of each test the store is always conditioned to 20 °C, no skip time is required. Hence the data used for parameter identification (“fitting”), shall start with the second test phase, and Ís = 20 °C shall be used as initial temperature for the store model. SIST EN 12977-4:2018

EN 12977-4:2018 (E) 13 6.3.3.2 Determination of all store parameters (except the vertical position of the temperature sensors) NOTE The determination of all store parameters, except of the vertical position of the temperature sensors, is partly based on references to EN 12977-3:2018, only new items are included. All parameters, which are determined by parameter identification, shall be identified during one parameter identification process. This requirement is not relevant for the determination of t

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