Study On The Optimization And Performance Of Residential Centralized Solar Domestic Hot Water System

At present,some problems are existed in the application of residential centralism solar domestic hot water system in our country: First,there is less research on the study of domestic hot water using pattern on the demand side of users;Second,the understanding of practical application effect of solar domestic hot water system is not clear,lacking the proof of practical operating data;Third,the evaluation index system is imperfect.Focusing on these problems,this paper mainly discusses hot water demand patterns,actual application effect,evaluation index and optimization of system performance,based on three research methods:questionnaires,engineering case test research and mathematical modeling.Firstly,hot water using mode,the forms of domestic hot water system,system using preferences and influence factors were investigated by questionnaires and field visits.Investigation results were concluded by effective 557 questionnaires recycled.Secondly,three typical residential solar hot water engineering cases located in Beijing,Chifeng and Tianjin were tested respectively,by which the thermal balance of “two ways into-two ways out” were counted.It was found that solar fraction as an important reference index of the system design had certain limitations when evaluating the actual running system.Three new kinds of evaluation index were put forward to reflect the actual consumption of the auxiliary conventional energy reasonably.Finally,combined with practical engineering,the mathematical model of heat-collecting unit,heat-supply unit and heat-using unit were established and formed the model of whole system.MATLAB language was used to write the calculation procedures based on the above model,providing support for the research of system optimization and performance.The main conclusions of the paper are listed as follows:(1)User requirement pattern has a great influence to the application effect of solar hot water system.Solar hot water system would cost even more energy than conventional hot water system if the operation control was inappropriate;(2)Actual operation energy consumption should be oriented in the evaluation of solar hot water systems.Evaluation idea should be changed from tracking solar into tracking conventional energy sources;(3)In the energy output of solar hot water system,heat dissipation increases with increasing cycle time of water supply.It was found that the cycle time of water supply system should be reduced as far as possible to reduce the heat loss and improve the system energy saving benefits on the premise that residents' hot water temperature demand were ensured.The research results of this thesis have certain significance on the research of domestic hot water consumption,residential hot water usage patterns,running effect analysis and evaluation and the control strategy research on the application of solar energy hot water system.