Optimization Of Packing Structure And Its Influence On The Heat And Mass Transfer Of The Heating Tower

Heat source tower heat pump is a new technology that uses low-grade heat in air to realize cooling and heating.It has good energy-saving benefits and application prospects in hot summer and cold winter areas.The heat source tower is the core device of the heat source tower heat pump system.The heat and mass transfer mechanism of heat source tower is similar to that of the cooling tower.The solution exchanges heat with the flowing air on the surface of the heat source tower packing.However,the heat exchange capacity of the heat source tower is very different in winter and summer.Latent heat transfer is dominant in summer and sensible heat transfer is dominant in winter,which leads to weak heat transfer capacity and large volume of heat source tower in winter.Therefore,measures must be taken to strengthen heat and mass transfer of heat source tower to improve heat transfer capacity.In order to solve this problem,this paper uses theoretical analysis,numerical simulation and experimental research methods to optimize the surface structure and size structure of the packing,which provides support for the miniaturization of heat source tower.In this paper,the theory of liquid flow on the surface of packing is deeply analyzed.Five different surface structures and three different wave heights of packings are selected according to the influencing factors of liquid flow on the surface of packing.The effects of surface structure and ripple height of filler on liquid diffusion characteristics and distribution uniformity were studied by setting up an experimental platform for filler surface flow characteristics,taking divergent water angle and liquid phase distribution non-uniformity coefficient as evaluation indexes.In order to solve the problem of non-uniform initial distribution of filling,a discrete liquid-liquid distribution model based on point source distribution was established.The influence of the distance between the filling points on the uniformity of filling distribution was studied,and the corresponding optimization measures were put forward.Based on the study of heat and mass transfer characteristics of cross flow heat source tower,a mathematical model of heat and mass transfer of heat source tower was established,and the distribution law of temperature,humidity and potential difference in the packing of heat source tower was studied and obtained.The heat and mass transfer performance of heat source tower under the combined action of multiple factors was studied by orthogonal test,and the influence of inlet parameters of heat source tower on its performance was revealed.The influence of the height-width ratio of Packings on the performance of heat source towers with different sizes of heat source towers was studied when the size of packedtowers changed and the volume of packings remained unchanged at constant solution flow rate and constant air flow rate.The influence of different packing spacing on the performance of heat source tower was studied,and on this basis,the packing arrangement was optimized.The results show that the increase of packing width and heat transfer capacity of high heat source tower is limited under constant solution flow rate and air flow rate,and the packing of heat source tower should be designed with large aspect ratio and the ratio of height to width should be controlled between 1.5 and 2.5 under constant packing volume.An experimental system for the performance of heat source towers was set up,and the heat and mass transfer characteristics and resistance characteristics of packed heat source towers with different sheet spacing under different solutions and air flow rates were studied.The experimental results show that the heat transfer capacity of heat source tower can be increased by reducing the distance between sheets.The resistance of packing increases with the decrease of the distance between sheets,and the increase of resistance leads to the decrease of air flow.The attenuation rate of air volume increases with the increase of air volume,but is less affected by the flow rate of solution.The maximum attenuation rate of air volume is 7.29% when the distance between sheets decreases from 15 mm to 9 mm.