Study On Performance Of Solar/Air Source Heat Pump Water Heating System In Guangzhou Area

As an inevitable process of social development issues, energy and environmental issueshave become the focus of widespread concern. With the accelerated pace of China to build amoderately prosperous society, energy production and energy consumption will be higherdemand, sustained and rapid growth in energy demand will make us face more seriousenvironmental stress. It has become a social consensus that improving energy efficiency,reducing the consumption of conventional energy and rational use of renewable energysources. The energy consumption of hot water is an important part of our energy consumptionin residential buildings. With the continuous improvement of living standards, which therewas a substantial part of the energy consumption will grow, especially in the hot and humidsouth China. In this paper, a case study in Guangzhou, by building experimental apparatus,running process were tested on solar water heating systems, air source heat pump waterheating systems and air source heat pump assisted solar water heating system throughout theyear. Their operating performance and economy were compared, to provide technical supportfor the application of Guangzhou domestic hot water systems for residential buildings.The experimental apparatus of solar(electric assist) water heating system, air source heatpump water heating systems and air source heat pump assisted solar water heating systemwere built and their thermal performance under typical seasonal weather conditions weretested in this thesis. The results show that the daily average solar collector efficiency valueschanged little with the seasons, at about53.5percent, when solar radiation is large, the dailyaverage collection efficiency decreased. The COPHof air source heat pump is influenced bynot only environmental temperature, water temperature, but also air relative humidity. Byanalyzing the measured data, the relational expression about COPHwith ambient temperature, relative humidity, water temperature was obtained: COPH=(0.0348t+0.1364φ+0.6867)×(-0.0041t2L+0.164tL+1.4378). It is the basis for the annual performance analysis of air-sourceheat pump water heating system.The mathematical model of each system under the meteorological parameters of typicalmeteorological year in Guangzhou were built, with the lowest energy consumption as theobjective function, to analysis the angle of solar collector and optimal operation mode of airsource heat pump assisted solar water heating system in Guangzhou. The results show thatbest inclination collectors installed is13.1°,and the opening time of assisted heat pump unitof air source heat pump assisted solar water heating system is17:00to make sure solarcollectors can be turned into full use.For10t daily water consumption for a student dormitory in Guangzhou, the annualenergy consumption of the three water systems were analyzed. Under the meteorologicalparameters of typical meteorological year, the annual operation energy consumption ofsolar(electric assist) water heating system, air source heat pump water heating system, airsource heat pump assisted solar water heating system are64556.2kWh,44636.17kWh,23043.52kWh,energy consumption of unit hot water are17.69kWh/t/d、12.23kWh/t/d、6.31kWh/t/d. The energy consumption of unit hot water of air source heat pump system is69.14%of that in solar(electric assist) water heating system. If the air source heat pump as anauxiliary heat source in combination with a solar water heating system, energy consumptionof unit hot water greatly reducing, is only35.7%of that in solar(electric assist) water heatingsystem.For solar(electric assist) water heating system, air source heat pump water heatingsystem and air source heat pump assisted solar water heating system, a comparative analysisof their energy-saving benefit, economic benefit and environmental benefit in Guangzhouwere made in this thesis. Results show that the annual operation energy consumption ofsolar(electric assist) water heating system, air source heat pump water heating system, airsource heat pump assisted solar water heating system are96.19%、66.53%、34.34%of thatconventional gas boiler water heating system; the dynamic annual cost of these three waterheating systems are92.47%、62.94%、61.81%of that conventional gas boiler water heatingsystem; within the use fixed number of year, the carbon dioxide emissions of these threewater heating systems reduce432.5t、549.05t、675.38t than that in conventional energy waterheating systems.