Performance Of Closed Heat Source Tower During Heating Conditions

Currently, renewable energy technology is one of the key measures to reduce heating and cooling energy costs.Closed heat source tower heat pump is a new renewable energy technologies that absorbs heat from the outdoor air in winter and rejects heat into outdoor air in summer at cost of a little electricity. It achieves that building heating and air conditioning terminal has no boiler, no carbon emissions, no electricity and energy-efficient auxiliary. With the promotion of closed heat source tower heat pump system,it has more and more problems in practical application. In order to further develop this technology, it is very necessary to study closed heat source tower heat pump systems.Firstly, the mathematical model of heat and mass transfer in closed heat source tower was proposed and was confirmed by experiment data. Secondly,an experimental test platform was built up for closed hea t source tower heat pump system, operating parameters of the entire system were testing comprehensively,including:inlet/outlet solution temperature and inlet/outlet air temperature in closed heat source tower, solution/air volume flow and so on. The experimental correlation of the outdoor air temperature with inlet solution temperature as well as the experimental heat transfer coefficient correl ations of air outside the closed heat source tower were fit out by experimental data. Finally, the heat transfer characteristics of bench closed heat source tower were studied by MATLABTRNSYS Real-time Dynamic Simulation Technology.It was indicated that the model is accurate enough to simulate the heat transfer characteristics in the closed heat source tower,the air enthalpy is linear distribution, the heat transfer effect of upper fin heat exchanger is better than the lower part, the center of the tower is firstly frosting. During the heating period, air temperature difference is close to solution temperature difference in Closed heat source tower, and equal 2~3℃ most of the time; When air temperature is below 5 ℃, relative humidity is higher than 56.8%, closed source heat pump system must turn on spray pump, otherwise frost formation would occur on closed heat source tower exchanger surfaces and be bad for normal operation of the system. In order to ensure the normal operation of the experimental system, the freezing point of spray solution must be below-8.4℃, and that of glycol solution must be below-12.7℃. During the heating period, A 90 k W total heat was absorbed by Closed heat source tower, and sensible heat is 8390 k W, the latent proportion of total heat is 31.8%, namely, sensible heat play a leading role in closed heat source tower, latent heat can not be ignored.