| The development of solar hot water in our country has gone through more than 30 years, various application technology is relatively mature, however the promotion and use of centralized solar hot water system in high-rise residential meet many problems, the energy-saving of the system has been questioned. Therefore, it's very important to analyze the energy consumption of centralized solar hot water system for its popularization and operation in the residential construction. The air source heat pump assisted solar centralized hot water system is combined with the heat pump technology and renewable energy technologies, the system makes full use of renewable energy and low grade energy, having great energy efficiency and advantages. This paper mainly analyze the energy consumption and cost in the application process of the centralized solar hot water system to the 24 hours water demand of Shenzhen high-rise residential, which can give to reasonable suggestions on it's promotion and application.Firstly this paper summarises the the operation principle, operation mode and the control method of air source heat pump assisted solar centralized hot water system. Then the mathematical calculation model of equipments and parameters: solar heat collecting system(including solar radiation, heat efficiency of flat plate collector, heat collection and heat efficiency of heat collection system), air source heat pump heating system(including refrigerant thermodynamic cycle, compressor, condenser, evaporator and throttle valve), thermal storage heating system(including heat loss of pipe network and water tank, the power of water pump and fan) and the system thermal load are established. According to the established mathematical model, this paper theoretically analyzed the variation law of heat collection set with time, radiation and ambient temperature, the relationship between heat efficiency of collection system and the radiation, the ambient temperature and the average temperature of the heat collection system, changes of water temperature with time and heat collection, the main influencing factors of heat production, thermal efficiency and running time of the the air source heat pump, delay relationship between heat collection and the heat load of the system., and ultimately determine the formula and the influence factors of the energy consumption of the system.Based on the above theoretical research, selected two communities which installed air source heat pump assisted solar centralized hot water system in Shenzhen. Collecting monthly data of opened households, water and power consumption in two projects for a period of more than one year, which obtained the mathematical fitting formula for change within one year of per capita water consumption and unit hot water consumption; redefined the Shenzhen's summer, winter and the transition season, analysing the causes of producing difference in summer through the comparison of theoretical energy consumption and the actual energy consumption; calculated the operating costs of the two projects. Then tested the thermal performance of project 1 in July, and recorded the parameters including ambient temperature, atmospheric irradiance, the inlet and outlet and circulating flow temperature of collecting system changes with the time. Based on analysis above, got the fitting equation of solar radiation variation, the relationship between the heat collector and the temperature of the inlet and outlet of the heat collection system, the relationship between the instantaneous heat collection efficiency and the heat collection efficiency of the system; Test the water temperature change of heat collecting tank and heat preservation performance of heat supply tank of project 2, verifying the delay relationship bettwen the temperature of water tank and the heat collecting capacity, and calculating the heat loss coefficient of water tank. Finally, the annual solar energy guarantee rate, annual conventional energy alternatives and environmental benefits of the two projects were evaluated.The results show that it's unreasonable in Shenzhen's high-rise residential to applly the centralized solar hot water system to ensure 24 hours of water supply system. There is obvious energy-saving advantage between the air source heat pump assisted solar hot water system and other conventional energy system, but the unified management with the artificial fees, management fees, equipment maintenance and other additional expenses make the system energy-saving but not financial. |
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