Numerical Simulation And Optimization Of The Heat Source Tower

With the energy crisis and environmental pollution increasingly prominent,especially in the winter heating period of northern China where haze frequently takes place,heating of the northern region has become a major event related to national livelihood.It is significantly related to the fact that the heating in northern China is still the main coal-fired boilers,which not only causing a waste of resources,but also exacerbating the environmental pollution.The heat source tower heat pump technology has been widely used in the Yangtze River Valley of China for its environmental protection,energy saving and high efficiency,which provides a new way to solve the heating problem in the north.However,the temperature in the winter of the northern region is lower and humidity is relatively low,for example,in Tianjin where temperature is maintained at about-5 ?,sometimes the temperature will be as low as-10 ?,making the application of heat source tower in the north faced with more challenges.In this paper,based on the open source heat source tower in the northern region,the choice of antifreeze solutions and heat source tower structure parameters optimization were experimentally and numerically studied.In experimental aspects: the physical properties of five different antifreeze solutions(calcium chloride,ethylene glycol,propylene glycol,glycerin and propylene carbonate)were measured and compared,and then,the best antifreeze solution suitable for the northern winter was selected.In simulation aspects: through the comparative analysis of the experimental results above,ethylene glycol solution of the mass fraction of 30% is selected as antifreeze solution.A three-dimensional numerical model of open source heat source tower was developed to simulate heat and mass transfer between antifreeze and air in heat source tower.In addition,in this model,the effect of the condensation phase transition of the air on heat transfer performance is also considered.Based on the model above,the effect of air inlet parameters(temperature,humidity,air inlet angle),antifreeze parameters(temperature,flow rate),spray angle and spray numbers on the heat transfer performance were investigated.The results are as follows:Ethylene glycol due to low freezing point,low viscosity,slightly corrosive,and low cost is more suitable as the frozen liquid in the northern region.Air inlet humidity,temperature and inlet angle affect the heat transfer performance of the heat source tower.The latent heat and total heat transfer increases with the increase of relative humidity and temperature,however,the heat transfer decreases with the increase of air inlet angle.Solution temperature and flow rate affect the heat transfer performance of the tower.As the temperature increases,the heat transfer decreases,however,heat transfer increased significantly with the increase of solution flow.Spray cone angle and spray number are important parameters affecting the performance of heat source tower.With the increase of the spray cone angle,the heat transfer increases and then decreases,moreover,an optimal spray angle exists.In addition,heat transfer increases with the increase of the spray numbers.The results show the appropriate selection of antifreeze solution makes the heat source tower possible to operate in the northern region of China,moreover,a reasonable heat source tower parameter design can obviously improve the heat transfer efficiency of the heat source tower,which provides a theoretical basis for the popularization of the heat source tower in the northern region.