Thermal stratification in solar storage tanks




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De Montfort University


Thesis or dissertation

Peer reviewed


The purpose of the work was to investigate the thermal stratification in solar storage containers. Three domestic thermally stratified hot water storage containers were designed with the main object of improving and stabilizing thermal stratification of the stored water as a means of improving the overall efficiency of solar water heating systems. Testing of the three storage containers was carried out under similar conditions and the results showedthat TYPEI storage container behaves as a three-segment stratified system, TYPEII storage container behaves as a two-segment stratified system with a thermocline occupying approximately half of the height of the storage container, and TYPEIII storage container behaves as a two-segment stratified system with a thermocline occupying two thirds of the height of the storage container. It was found that TYPEI storage container, with a LID equal to 3/1, gave the best results in terms of heat collected, and also had the maximum stratification which is the main goal of this study. The effect of each of three flow rates (0.01 kg/Sm2 , 0.015 kg/sm2 , 0.02 kg/sm2 ) on stratification was studied and it was found that the flow rate of 0.01 kg/Sm2 of collector area gave the better result. A low-cost simulator for studying the performance of solar energy storage containers was designed. The design was based on a relatively inexpensive micro-computer linking into a mains power regulator with an 8-bit digital control system. Meteorological data was used to compute radiation income on any inclined plane and the output to the power regulator is controlled by the computed instantaneJus rate of energy gain from the collector system undergoing simulation.A comparison has been made between some of the experimental and theoretical results for mE I storage container. The theoretical prediction was based on two mathematical IOOdels of Duffie and 2 44 Beckman , and Close • A computer system model has been developed to assist in the design of a solar water heating system.





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