Application And Performance Study Of Solar Energy And CO₂ Air Source Heat Pump In Kunming

Under the dual pressures of energy crisis and environmental pollution,the development and utilization of renewable energy represented by solar energy has received more and more attention.However,solar energy is susceptible to climate,there is instability,it can not be operated around the clock,and the requirements of the outlet water temperature cannot be guaranteed.An auxiliary heat source must be provided to ensure the actual heating effect.Therefore,the combination of solar energy and CO₂ air source heat pump is used as a source of domestic hot water to complement each other.Firstly,based on the basic theory of solar water heating system and CO₂ air source heat pump water heating system,the optimal coupling mode of solar energy and CO₂ air source heat pump is discussed.On this basis,a combined heating system of solar energy and CO₂ air source heat pump is designed and built for a hotel hot water renovation project in Kunming.Secondly,the influence of the inlet water temperature,ambient temperature and heating temperature of gas cooler on the thermal performance of CO₂ air source heat pump is studied.The results show that the heating coefficient of heat pump is higher when the inlet water temperature is 15 and the heating temperature is 60⁷5 taking into account the heating temperature and COP of heat pump.On a typical test day,the thermal performance of solar energy and CO₂ air source heat pump combined heating system in three different operation modes was tested.The test results show that the average daily solar collector efficiency is about 46.6%when a single solar water heating system runs;the average heating coefficient of a heat pump is about 3.6 when a single CO₂ air source heat pump water heating system runs;and the heating coefficient of a heat pump can reach more than 2.8 in the coldest month when a combined solar and CO₂ air source heat pump is running.In addition,the external performance file is compiled by TRNSYS software to create a CO₂ air source heat pump water heater model with rated power of 18 kW and rated heat of 70 kW.On this basis,the simulation models of solar water heating system,CO₂ air source heat pump water heating system and end mixing solar energy and CO₂ air source heat pump combined heating system are established respectively.Taking the spring equinox,summer solstice,autumn equinox and winter solstice as typical climatic conditions,the variation law of water supply temperature and water supply quantity of solar water heating system and CO₂ air source heat pump with time under certain water consumption load is analyzed.The results show that under typical climatic conditions,the water supply temperature and water supply quantity of solar water heating system in most time are analyzed.The water supply does not meet the water load,and the remaining heat required is provided by CO₂ air source heat pump,which can provide heating on demand.The variation of water supply temperature of water storage tank,water supply temperature of high temperature water tank and water supply temperature after mixing with time under different typical climatic conditions was also studied.The variation of mixing ratio of high temperature water and medium and low temperature water with time is analyzed emphatically.The results showed that the average mixing ratio of high temperature water and medium and low temperature water was 0.97 in spring equinox,and the average mixing ratio of high temperature water and medium-low temperature water was 1.05 in summer solstice,and the average mixing ratio of high temperature water and medium-low temperature water was 0.75 in autumn equinox,and the average mixing ratio of high temperature water and medium-low temperature was 1.83 in winter solstice.Finally,the economy and environmental protection of the combined heating system of solar energy and CO₂ air source heat pump in Kunming are analyzed.