GENERAL-MODEL FOR TESTING SOLAR DOMESTIC HOT WATER-SYSTEMS

For modelling solar domestic hot water (SDHW) systems, a plug flow store model is presented. It is used in conjunction with the dynamic system testing algorithm to predict the long term performance of SDHW systems from short term test data. The basic property of a plug flow model is its capability of modelling drawoffs without any mixing inside the store. As an extension, the model developed in this paper covers the range between pure plug flow and full mixing. The degree of draw off mixing is characterized by a continuous parameter instead of a (discrete) number of thermal nodes which actually is defined neither for a plug flow model nor for a real system. Less than ten model parameters characterize a system under test. It was found that the parameters can be identified in short time (two to four weeks outdoors) for a large class of systems, e.g. thermosyphon systems or integrated collector store (ICS) systems, systems with load side heat exchanger, auxiliary heater, and heat pipe collectors. A summary of experimental results for different systems is given.