Study On Circulating Characteristics Of Domestic Solar Water Heater With Wall - Mounted Natural Circle Flat Plate

Flat plate domestic solar water heater is giver priority to natural circulation. Thethermal efficiency is directly affected by the circulation quality of the water heater.Current research on natural circulation characteristics of the water heater is stillrelatively limited for the reason that the natural circulation flow rate of water heater isweak and complex and restricted by measuring instruments and experimentalconditions. Flat plate solar collector is the key component of a solar hot water heatingsystems, and the performance of the collector directly determines the efficiency of theheating systems. The current research hot spot is still focused on improving thethermal performance of the collector. In this paper, characteristics and efficiency ofthe natural circulation of hot water systems studied by establishing the naturalcirculation model of domestic solar hot water systems and combining with theexperimental data. Analysis of temperature field, flow field, and the efficiency unitdistribution is also carried out using CFD numerical simulation. Finally, water heating,temperature stratification and thermal performances in the storage tank of flat platewater heating systems have been predicted by artificial neural network method. Andthis provides a valuable reference evaluation technical means for thermalperformances of hot water heating systems. The results of the study are as follows:1. Based on experimental measurements, to establish natural circulation massflow rate model of flat plate solar water heating systems, and to realize the calculationof natural circulation mass flow rate. Data analysis found that: The natural circulationflow rate has a good linear correlation with the solar irradiance. The height that uppercirculation pipe connects with the position of the tank interfaces has great impact onthe natural circulation.2. Establish simplified CFD model of flat plate collector, and collector tube ishorizontally placed. The credibility of simulation results are verified through theexperimental measurement. Using CFD methods to simulate and analyze thetemperature field and flow field of collector. The results show：because of the effects of the inlet mass flow rate,temperature and enhanced solar irradiance thant the massflow distribution in the pipe is not uniform.3.The established artificial neural network prediction model can better predictthe water temperature stratification data during the temperature rise of systems undersunny weather after trained under cloudy climate conditions, which shows betterpredictive ability extrapolation and prediction accuracy.The above results have a deep understanding on natural circulationcharacteristics of flat plate solar water heating systems, and also a good referencevalue in the design of solar water heating systems. In addition, provide an artificialintelligence neural network technology thermal performance test method that lowerstest conditions.