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THE EUROPEAN SOLAR STORAGE TESTING GROUP CO-ORDINATOR'S REPORT.

Objective

THE AIM OF THE CEC CONCERTED ACTION THE EUROPEAN SOLAR STORAGE TESTING GROUP IS TO DEVELOP PROCEDURES BOTH FOR A SIMPLE TEST METHOD FOR THE BASIC CHARACTERIZATION OF STORAGE SYSTEMS AND FOR AN EXTENSIVE TEST METHOD, RESULTING IN DETAILED CHARACTERIZATION OF THE STORAGE SYSTEMS. THE RESULTS OF THE EXTENSIVE TEST SHOULD YIELD PARAMETER VALUES FOR A CALCULATION MODEL OF THE STORAGE SUBJECTED TO THE TESTS. THE DEVELOPMENT OF SUCH A GENERAL MODEL IS A SPECIAL TASK WITHIN THE RESEARCH PROJECT. THE JOINT ACTION PROGRAMME CONSISTS OF THREE SUCCESSIVE SERIES OF TESTS.

PARTICIPANTS IN THE PROJECT ARE: THE TECHNICAL UNIVERSITY OF DENMARK; THE DANISH SOLAR ENERGY TESTING LABORATORY; ECOLE NATIONALE SUPERIEURE DES MINES DE PARIS (JOINTLY WITH CSTB); THE UNIVERSITY OF STUTTGART; THE UNIVERSITY COLLEGE CARDIFF AND THE TNO INSTITUTE OF APPLIED PHYSICS (TPD). THE PROJECT IS CO-ORDINATED BY THE TPD.
EVALUATION OF THE FIRST SERIES OF TESTS (A ROUND ROBIN TEST), TOGETHER WITH RESULTS COMING FROM VARIOUS SUBTASKS HAVE MADE CLEAR WHICH QUANTITIES ARE NECESSARY FOR A GOOD THERMAL CHARACTERIZATION OF HEAT STORAGE DEVICES. SUCH QUANTITIES ARE THE STORAGE CAPACITY, THE HEAT LOSS OF THE STORE AND THE STORAGE EFFICIENCY; THE LATTER IS A MEASURE FOR THE AMOUNT OF HEAT WHICH CAN BE CHARGED TO OR DISCHARGED FROM THE STORE WITHIN A CERTAIN TIME. THESE QUANTITIES CAN BE DERIVED DIRECTLY FROM THE RESULTS OF A SO-CALLED TEMPERATURE STEP RESPONSE TEST. OTHER QUANTITIES, LIKE THE EFFICIENCY OF THE HEAT EXCHANGER IN THE STORE AND THE HEAT TRANSFER BETWEEN DIFFERENT PARTS OF THE STORE (E.G. IN CASE OF STAND-BY WITH A HOT TOP OR DURING STRATIFIED (DIS-)CHARGE) CAN NOT BE DERIVED DIRECTLY FROM A TEST, AT LEAST NOT WITHOUT INTERNAL TEMPERATURE MEASUREMENTS. SUCH PARAMETERS ARE IDENTIFIED IN A FITTING PROCEDURE, BY AN AUTOMATED PROCESS OF COMPARING THE RESULTS OF A STORAGE MODEL WITH THE TEST RESULTS.
THIS REVEALS ALREADY THE STRONG INTERACTION BETWEEN THE DEVELOPMENT OF A SET OF TEST PROCEDURES AND THE MODEL DEVELOPMENT. CONCERNING THE DEVELOPMENT OF A GENERAL MODEL TWO APPROACHES ARE CURRENTLY UNDER INVESTIGATION: A 4-PORT STRORAGE MODEL AND A MODEL IDENTIFICATION METHOD. ALTHOUGH BOTH APPROACHES HAVE BASICALLY DIFFERENT STARTING POINTS, IT IS VERY PROMISING TO NOTICE HOW EACH STEP IN THE DEVELOPMENT MEANS A FURTHER CONVERGENCE TOWARDS A "GENERAL" STORAGE MODEL.
PARAMETER VARIATIONS WITH THE STORAGE MODELS ARE ALSO CARRIED OUT TO FIND THE INFLUENCE OF THE MODELS' APPROXIMATIONS AND THE EFFECT OF THE CHOSEN INPUT DATA ON THE RESULTS. FOR INSTANCE, THE INFLUENCE OF THE SO-CALLED NUMERICAL DIFFUSION ("SMEARING EFFECT") WHICH MAY LEAD TO ERRONEOUS CALCULATION RESULTS.
CONSIDERABLE PROGRESS IS MADE, NOT ONLY ON THESE TOPICS, BUT ALSO ON ITEMS LIKE THE DEVELOPMENT OF A FORTRAN PACKAGE TO PROCESS THE MEASURED DATA, INCLUDING A DETAILED ERROR ANALYSIS, THE DEVELOPMENT OF A SPECIAL TEST TO QUANTIFY THE HEAT LOSS DISTRIBUTION OVER THE STORAGE SURFACE, E.G. HEAT LOSS FROM A PARTLY (DIS-)CHARGED STORE ("HOT TOP"), THE DEVELOPMENT OF A DYNAMIC TEST TO EVALUATE THE PARAMETERS DERIVED FROM THE TESTS AND THE SELECTED STORAGE MODEL, ETCETERA.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

NEDERLANDSE ORGANISATIE VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TNO*
Address
1,Stieltjesweg 1
2628 CK Delft
Netherlands

Participants (5)

Business Unit of TNO Built Environment and Geosciences
Netherlands
Address
Van Mourik Broekmanweg 6
2628 XE Delft
CARDIFF UNIVERSITY
United Kingdom
Address
Newport Road 30-36
Cardiff
CENTRE SCIENTIFIQUE ET TECHNIQUE DU BATIMENT - CSTB
France
Address
4, Avenue Du Recteur Poincare
75782 Paris
TECHNICAL UNIVERSITY OF DENMARK
Denmark
Address
Anker Engelundsvej 1, Building 101
2800 Lyngby
UNIVERSITAET STUTTGART
Germany
Address
Keplerstrasse 7
70174 Stuttgart