Study On Auxiliary Performance Of Solar Hot Water System And Air Source Heat Pump Based On Mild Climate

Energy use has become a crucial concern in the last decades because of rapidincrease in energy demand. There are two problems have to be solved. One is how tomeet the demand of sufficient energy supply in the economic development; thesecond is how to improve energy efficiency. In China, Solar thermal utilizationtechnology has been mature in the area of solar energy utilization. However, solarenergy is low heat flux and unstable, which is greatly influenced by the weather.Thus configuration of the reliable auxiliary energy is essential to ensure a steadysupply of hot water. Moreover, the design of auxiliary energy needs to make areasonable choice in order to obtain stability, energy conservation and economicefficiency.In this paper, experimental study and theoretical analysis of the operationalcharacteristics of household solar water heating system are investigatedsystematically under the local meteorological conditions in Kunming. The researchwork was carried out as follows:(1) For the established household flat-plate solar hot water system，its operatingcharacteristics throughout the day was analyzed experimentally and theoretically.The results showed that the solar irradiance had few influence on the performancecharacteristics of the solar water heater under different weather conditions. Thesystem efficiency kept around52%when the daily total radiation varied from5.3MJ to22.2MJ; The study on the relationship between the daily average efficiencyand the auxiliary energy under typical weather conditions was helpful to the designof the auxiliary energy supply for the all-weather operation of the solar water heaterand the decision of the area of the heat collectors.(2) A model of balcony-type flat-plate solar water heater system on the platformof TRNSYS program was built. The results of TRNSYS simulation was comparedwith the experimental results of the system, it is shown that the agreement betweenthem is quite good. The parameters were changed in the model, the annual cumulative operating characteristics of the system with the typical Meteorologicalyear weather data was calculated in Kunming and Beijing.(3) The annual solar radiation and ambient temperature changes in thedistribution were analyzed in Kunming. According to the practical air source heatpump assisted solar hot water system, we established mathematical model andstudied operating characteristics of the system in the case of monthly average daywith the parameters typical meteorological year, obtaining the heat provided by solarhot water system and the rest of the heat provided by air source heat pump.Theseefforts laid the foundation for further improving the performance of the air sourceheat pump assisted solar hot water system.