Research On Heat Transfer Of Heat Source Tower And Performance Of Heat Pump System

As an important part of building energy consumption,the heating energy consumption and air conditioning energy consumption of buildings are important parts.According to different climate characteristics,it is suggested that appropriate cold and heat sources can effectively reduce the energy consumption of air conditioning.In order to adapt to the climate characteristics of hot summer and cold winter,an open cross-flow heat source tower heat pump system is proposed.The following research is done for the heat source heat pump and its systemFirst,the principle of heat and mass transfer of the open-type cross-flow heat source tower is analyzed,and the mathematical model of heat and mass transfer of the split-type cross-flow heat source tower is constructed according to the principle.Use Fortran language to realize the calculation of discrete equations.The simulation calculation components of the open cross-flow heat source tower and the heat source tower heat pump unit are established in the TRNSYS simulation software.Then,TRNBuild was used to calculate the hourly building load of commercial buildings,residential buildings,and office buildings in Chongqing.Under the same building load conditions,the calculation of the open-type cross-flow heat source tower heat pump system under the meteorological parameters of five cities was completed.The heat transfer performance of the cross-flow heat source tower during the heating season was compared.The changes of the temperature and temperature difference between the inlet and outlet of the solution,the degree of approximation,the ratio of heat transfer to latent heat,the amount of condensate of the cross-flow heat source tower,and the mass fraction of antifreeze solution under different climatic conditions were compared and analyzed.Then,under the meteorological conditions of Chengdu,Chongqing,Wuhan,Changsha,and Nanchang,the hourly load changes of buildings in each city were analyzed.The heat pump system is built through TRNSYS calculation software.The energy-saving and economic efficiency of the open-type cross-flow heat source tower heat pump system under different urban meteorological parameters throughout the year are studied.The average value of the coefficient of performance of the heat source tower heat pump system in Chengdu and Chongqing during the heating season is the largest,while that of Wuhan is the smallest.In the air-conditioning season,Chengdu and Chongqing have the smallest average system performance coefficients.In areas with higher air humidity,the system has higher performance in the heating season,but lower performance in summer;the opposite is true in areas with lower air humidity.In Chengdu,Chongqing,and Nanchang,the operating cost of the unit output of cold and heat is relatively small,and the economy is better;Wuhan’s economy is poor.Finally,after TRNSYS system simulation calculation,the heat source tower heat pump unit,air source heat pump unit and gas boiler + chiller are compared and studied.Based on the energy-saving effect of the year-round operation,compared with the other two models,the heat source tower heat pump is the best.Its primary energy utilization rate is 4.8% and 15.2% higher than that of the conventional chiller + boiler system model and the air source heat pump system.The operating cost of the chiller + boiler system is4.5% higher than that of the heat source tower heat pump system.The annual unit operating cost of the heat source tower heat pump system is 16.8% lower than that of the air source heat pump system unit,and the system operating cost is 4.1% lower than that of the air source heat pump system.