EN 12977-3:2012

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.HPThermische Solaranlagen und ihre Bauteile - Kundenspezifisch gefertigte Anlagen - Teil 3: Leistungsprüfung von Warmwasserspeichern für SolaranlagenInstallations solaires thermiques et leurs composants - Installations assemblées à façon - Partie 3 : Caractérisation des
performances des dispositifs de stockage pour des installations de chauffage solairesThermal solar systems and components - Custom built systems - Part 3: Performance test methods for solar water heater stores91.140.65Oprema za ogrevanje vodeWater heating equipment91.140.10Sistemi centralnega ogrevanjaCentral heating systems27.160Solar energy engineeringICS:Ta slovenski standard je istoveten z:EN 12977-3:2012SIST EN 12977-3:2012en,fr,de01-julij-2012SIST EN 12977-3:2012SLOVENSKI
STANDARDSIST EN 12977-3:20081DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 12977-3
April 2012 ICS 27.160 Supersedes EN 12977-3:2008English Version
Thermal solar systems and components - Custom built systems - Part 3: Performance test methods for solar water heater stores Installations solaires thermiques et leurs composants - Installations assemblées à façon - Partie 3: Méthodes d'essai des performances des dispositifs de stockage des installations de chauffage solaire de l'eau
Thermische Solaranlagen und ihre Bauteile - Kundenspezifisch gefertigte Anlagen - Teil 3: Leistungsprüfung von Warmwasserspeichern für Solaranlagen This European Standard was approved by CEN on 19 February 2012.
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, 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
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12977-3:2012: ESIST EN 12977-3:2012

Store model benchmark tests . 35A.1General . 35A.2Temperature of the store during stand-by . 35A.3Heat transfer from heat exchanger to store . 35Annex B (normative)
Verification of store test results . 37B.1General . 37B.2Test sequences for verification of store test results . 37B.2.1General . 37B.2.2Verification sequences from measurements on a store testing stand . 37B.2.3Test sequences obtained during a whole system test according to ISO 9459-5 . 44B.3Verification procedure . 44B.3.1General . 44B.3.2Error in transferred energies . 44B.3.3Error in transferred power . 45Annex C (normative)
Benchmarks for the parameter identification . 46Annex D (informative)
Requirements for the numerical store model . 47D.1General . 47D.2Assumptions . 47D.3Calculation of energy balance . 47SIST EN 12977-3:2012

Determination of store parameters by means of “up-scaling” and “down-scaling”. 49E.1General . 49E.2Requirements . 49E.3Determination of store parameters . 50E.3.1Thermal capacity of store . 50E.3.2Height of store . 50E.3.3Determination of heat loss capacity rate . 50E.3.4Relative heights of the connections and the temperature sensors . 50E.3.5Heat exchangers . 50E.3.6Parameter describing the degradation of thermal stratification during stand-by . 51E.3.7Parameter describing the quality of thermal stratification during direct discharge . 51Annex F (informative)
Determination of hot water comfort . 52Bibliography . 53
Tables
Table 1 — Classification of the stores . 12Table 2 — Measuring data . 16Table 3 — Compilation of the test sequences . 19Table 4 — Flow rates and store inlet temperatures for Test C (group 1). 20Table 5 — Flow rates and store inlet temperatures for Test C (group 2). 21Table 6 — Flow rates and store inlet temperatures for Test C (group 3). 21Table 7 — Flow rates and store inlet temperatures for Test C (group 4). 22Table 8 — Flow rates and store inlet temperatures for Test L (group 1) . 23Table 9 — Flow rates and storage device inlet temperatures for Test L (group 2) . 24Table 10 — Flow rates and store inlet temperatures for Test L (group 3) . 24Table 11 — Flow rates and store inlet temperatures for Test L (group 4) . 25Table 12 — Flow rates and store inlet temperatures for Test NiA (group 2 or 4) . 26Table 13 — Flow rates and store inlet temperatures for Test EiA . 27Table 14 — Flow rates and storage device inlet temperatures for Test NA (groups 1 and 3) . 28Table 15 — Flow rates and store inlet temperatures for Test NB (group 1 and 3) . 28Table 16 — Flow rates and store inlet temperatures for Test NB (groups 2 and 4) . 29Table 17 — Flow rates and store inlet temperatures for Test EB . 30Table A.1 — Results of the analytical solution. 36Table B.1 — Compilation of the verification sequences . 38Table B.2 — Flow rates and storage device inlet temperatures for Test V (group 1). 39Table B.3 — Flow rates and storage device inlet temperatures for Test V (group 2). 40Table B.4 — Flow rates and storage device inlet temperatures for Test V (group 3). 41Table B.5 — Flow rates and storage device inlet temperatures for Test V (group 4). 42Table B.6 — Flow rates and storage device inlet temperatures for Test NiA (group 2 or 4) . 43Table B.7 — Flow rates and storage device inlet temperatures for Test EiV . 44 SIST EN 12977-3:2012

Stores tested according to this document are commonly used in solar hot water systems. However, the thermal performance of all other thermal stores with water as a storage medium can also be assessed according to the test methods specified in this document. The document applies to stores with a nominal volume between 50 l and 3 000 l. This document does not apply to combistores. Performance test methods for solar combistores are specified in EN 12977-4. 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 12897, Water supply – Specification for indirectly heated unvented (closed) storage water heaters EN ISO 9488:1999, Solar energy — Vocabulary (ISO 9488:1999) ISO 9459-5, Solar heating — Domestic water heating systems — Part 5: System performance characterization by means of whole-system tests and computer simulation 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN ISO 9488:1999 and the following apply. 3.1 ambient temperature mean value of the temperature of the air surrounding the store 3.2 charge process of transferring energy into the store by means of a heat source 3.3 charge connection pipe connection used for charging the storage device 3.4 combistore one store used for both domestic hot water preparation and space heating SIST EN 12977-3:2012

flow rate which is achieved when the mean value of V~& over the period of 0,5 “reduced charge/discharge volumes” (see 3.34) is within V~&± V~& × 0,1 Note 1 to entry: The symbol ”~” above a certain value indicates that the corresponding value is a mean value. 3.9 dead volume/dead capacity volume/capacity of the store which is only heated due to heat conduction (e.g. below a heat exchanger) 3.10 direct charge/discharge transfer or removal of thermal energy in or out of the store, by directly exchanging the fluid in the store 3.11 discharge process of decreasing thermal energy inside the store caused by the hot water load 3.12 discharge connection pipe connection used for discharging the storage device 3.13 double port corresponding pair of inlet and outlet connections for direct charge/discharge of the store Note 1 to entry: Often, the store is charged or discharged via closed or open loops that are connected to the store through double ports. SIST EN 12977-3:2012

time integral of the measured power over one or more test sequences, excluding time periods used for conditioning at the beginning of the test sequences 3.24 measured power, Px,m power calculated from measured volume flow rate as well as measured inlet and outlet temperatures 3.25 measured store heat capacity measured difference in energy of the store between two steady states on different temperature levels, divided by the temperature difference between these two steady states SIST EN 12977-3:2012

Cs thermal capacity of the entire store, in J/K cp specific heat capacity, in J/(kg K) Pn nominal heating power, in W Px,m measured power transferred through the charge (x = C) or discharge (x = D) circuit, in W Px,p predicted power transferred through the charge (x = C) or discharge (x = D) circuit, in W Qx,m measured energy transferred through the charge (x = C) or discharge (x = D) circuit, in J Qx,p predicted energy transferred through the charge (x = C) or discharge (x = D) circuit, in J tst time required to achieve a steady state, in s tx,f transfer time for charging (x = C) or discharging (x = D), in s SIST EN 12977-3:2012

relative error in mean power transferred during charge (x = C) or discharge (x = D), in % εx,Q
relative error in energy transferred during charge (x = C) or discharge (x = D), in % ρ density, in kg/m³ 5 Store classification Hot water stores are classified by distinction between different charge and discharge modes. Five groups are defined as shown in Table 1. Table 1 — Classification of the stores 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 may have one or more additional electrical heating elements. SIST EN 12977-3:2012

The circuits are intended to simulate the charge and discharge loop of the solar system and to provide fluid flow with a constant or well-controlled temperature. The full test stand consists of one charge and one discharge circuit. NOTE 1 If the store consists of more than one charge or discharge devices (e.g. two heat exchangers), then these are tested separately. The testing stand shall be located in an air-conditioned room where the room temperature of 20 °C should not vary more than ± 2 K during the test. Both circuits shall fulfil the following requirements:  the flow rate shall be adjustable and stable within ± 5 %;  the working temperature range shall be between 10 °C and 90 °C; NOTE 2 A typical heating power of the charge circuit is in the range of 15 kW.  the minimum cooling power in the discharge circuit shall be at least 25 kW at a fluid temperature of 20 °C; NOTE 3 A typical heating power of the discharge circuit is in the range of 25 kW. NOTE 4 If mains water at a constant pressure and a constant temperature below 20 °C is available, it is recommended to design the discharge circuit in a way, that it can be operated as closed loop or as open loop using mains water to discharge the store.
 the minimum heating up rate of the charge circuit with disconnected store shall be 3 K/min;  the minimum available electrical heating power for electrical auxiliary heaters shall be 6,0 kW.
NOTE 5 The electrical power of the pump (P101) should be chosen in such a way that the temperature increase induced by the pump (P101) is either less than 0,6 K/h when the charge circuit is "short-circuited" and operated at room temperature (“short-circuited” means that no storage device is connected and SV102, V113, V115 and V116 are closed, see Figure 1) or an additional cooling device should be integrated in the circuit.
Key FF flow meter HX heat exchanger OP overheating protection P pump
ST store (belonging to test facility) SV solenoid valve TT temperature sensor TIC temperature indicator and controller V valve Figure 1 — Charge circuit of the store-testing stand The heating medium water in the charge circuit (see Figure 1) is pumped through the cooler (HX101) and the temperature controlled heaters (TIC106) by the pump (P101). A buffer tank (ST101) is used to balance the remaining control deviations. By means of the bypass (V107) the flow through the store can be controlled, it also ensures a continuously high flow through the heating section and therefore good control characteristics. With the solenoid valve (SV101), the heating medium can bypass the store to prepare a sudden increase of the inlet temperature into the store. The temperature sensors are placed near the inlet (TT101) and outlet (TT102) connections of the store; the connection to the store is established through insulated flexible pipes.
The charge circuit can be operated closed, under pressure (design pressure 2,5 bar, membrane pressure expansion tank and pressure relief valve (V109)) as well as open (valve (V108) open) with the tank (ST102) serving as an expansion tank. A calibration of the installed flow meter (FF105) is possible by weighing the mass of water leaving the valve (V112). The installation is equipped with the usual safety devices, i.e. pressure relief valve (V117) and overheating protection device (OP101). The discharge circuit (see Figure 2) is constructed in a similar way. It includes two coolers – (HX201) and (HX202) – and a temperature controlled heating element (TIC206) with 5 kW heating power. The discharge circuit can either be operated in open circulation with water from the net or it can be operated in closed circulation. During open operation, the water is led via the safety equipment (V201) and flows through the coolers, the heating section and the flow meter (FF205) into the store. The hot water leaving the store flows through the solenoid valve (SV201) and the valve (V210) into the drain. The valve (V212) is closed. For heating the water it is recommended to increase the flow through the heating section with the pump (P201) in order to improve the control performance; the additional volume flow returns through the bypass (V209). SIST EN 12977-3:2012

Key FF flow meter HX heat exchanger P pump SV solenoid valve
TT temperature sensor TIC temperature indicator and controller V valve Figure 2 — Discharge circuit of the store-testing stand SIST EN 12977-3:2012

NOTE Uncertainties in the difference in the charging and discharging medium temperature, between store inlet and store outlet close to 0,02 K can be achieved with modern well matched and calibrated transducers. Hence, it is possible to measure low temperature differences with small uncertainties. The relevant data shall be measured at least every 10 s and the measured data shall be recorded as mean values of at most three measured values. The temperature sensors shall have a relaxation time of less than 10 s (i.e. 90 % of the temperature variation is detected by the sensor immersed in the heat transfer fluid within 10 s after an abrupt step in the fluid temperature). Prior to each store test a zero measurement should be performed where the fluid in the charge or discharge circuit is pumped over the short-circuited charge or discharge circuit. “Short-circuited” means that flow pipe and return pipe of the corresponding circuits are directly connected (recommended volume flow approximately 0,6 m³/h, temperatures 20 °C, 40 °C, 60 °C, 80 °C). If the measured temperature difference exceeds the permissible uncertainty of 0,05 K, the temperature sensors shall be calibrated. A reference heater may also be used for the zero measurement. SIST EN 12977-3:2012

The connections at the storage device, as delivered by the manufacturer, are considered as the thermal demarcation between the storage device and the testing stand.
The solenoid valves shall be placed as near as possible to the inlet and outlet connections of the storage device.
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.
NOTE 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 e.g. if the pipe is directly going downwards after leaving the store or by using a siphon. 6.3 Test and evaluation procedures 6.3.1 General The aim of store testing as specified in this document is the determination of parameters required for the detailed description of the thermal behaviour of a hot water store. Therefore, a mathematical computer model for the store is necessary. The basic requirements for suitable models are specified in Annex A and Annex D. The following parameters shall be known for the simulation of a store being part of a thermal solar system. a) Stored water: 1) height; 2) effective volume respectively effective thermal capacity; 3) heights of the inlet and outlet connections; SIST EN 12977-3:2012

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 and mass flow rate (in case the mass flow rate is variable); 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). 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, its length is also required;
3) efficiency that characterises the fraction of the electric power converted to thermal and 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 A) can be subdivided into phases indicated by a number (e.g. A1 – 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, only the ambient temperature shall be measured and recorded.
NOTE 5 One essential point of the described methods is that measurements inside the store are avoided.
NOTE 6 The determination of all the store parameters listed above is possible only according to the method described under 6.3.3. However, some of the parameters may also be determined according to the method described under 6.3.2. SIST EN 12977-3:2012

group 1
group 2
group 3
group 4
6.3.2.2.2 6.3.2.2.3 6.3.2.2.4 6.3.2.2.5 Determination of the thermal stratification during discharge with a 'high' flow rate Test S
6.3.2.3 Determination of the stand-by heat loss capacity rate of the entire store Test L:
group 1
group 2
group 3
group 4
6.3.2.4.2 6.3.2.4.3 6.3.2.4.4 6.3.2.4.5 Determination of the heat transfer capacity rate and the position of the auxiliary heat exchanger(s) Test NiA for stores with auxiliary heat exchanger(s) 6.3.2.5 Determination of the position(s) and length(s) of the electrical heating source(s) Test EiA for stores with electrical heating source(s) 6.3.2.6 Determination of the degradation of thermal stratification during stand-by Test NiA and Test NiB for stores of groups 1 and 3
Test NiA and Test NiB for stores of groups 2 and 4
Test EiA and Test EiB for stores with electrical auxiliary heating sources only 6.3.2.7.2
6.3.2.5 6.3.2.7.3 6.3.2.6 6.3.2.7.4
NOTE 1 The exact vertical positions of the upper connections of the heat exchangers above which the store is charged in a mixed way, have a minor influence on the thermal behaviour of the store. Hence, these vertical positions do not need to be determined by means of parameter identification. It is recommended to measure the corresponding positions or to determine them from the drawing of the store. The following applies to all tests for determination of the heat transfer capacity rate of the heat exchangers. The flow rates through the heat exchangers as well as the heating powers which are given for the determination of the heat transfer capacity rate (dependent on temperature) of the heat exchangers are recommendations. Other flow rates and heating powers may also be used if they better correspond to the real operating conditions or are specified in the manufacturer's inst
...