Analysis And Research On Heat Transfer Performance Of The Open Heat Source Tower Under Winter Conditions

For a long time in the future,building energy consumption will be the main growth point of energy consumption in China's economic development.The research and application of building energy saving technology will have an important impact on energy structure and consumption.Heat source tower heat pump technology is widely used in building energy saving,which is of great significance to the adjustment of energy structure.In summer,hot water with high enthalpy value and air with low enthalpy value are directly contacted in the tower through the surface of packing for heat transfer,and heat of hot water is transferred to air driven by enthalpy difference.The cooling limit is the wet bulb temperature of air.In winter,low enthalpy value circulating solution absorbs heat from high enthalpy low temperature wet air,thus providing low temperature potential heat source and endothermic limit temperature for heat pump mainframe.For air wet bulb temperature,high heat transfer efficiency,multi-purpose tower,increased the utilization rate of equipment and energy saving advant ages,in line with the prospects of sustainable development.As the key equipment of heat source tower heat pump system,the performance of open heat source tower directly affects the working efficiency of open heat source tower heat pump system.The analysis and research of heat and mass transfer performance of open heat source tower is very important for the optimization of heat pump technology.After reading relevant literature and information,this paper studies the heat transfer performance of open hea t source tower by combining theory with experiment.The following work has been done:(1)The mechanism of gas-liquid heat and mass transfer in the tower is analyzed,and the heat and mass transfer model of open heat source tower in winter is established.The heat and mass transfer mechanisms of air and circulating solution in countercurrent and smooth open heat source towers during heat and moisture exchange are described respectively.The mathematical model of heat and mass transfer of open heat source tower in winter is established,and the heat change caused by the change of water quantity in the process of heat and mass exchange in the tower is not neglected.The heat transfer differential equation is solved numerically by Runge-Kutta method,and the computer solving process of counter-flow and parallel-flow open heat source towers is given respectively.The accuracy of the model is verified by experimental data,and the error is within 12%.It satisfies the requirement of engineering precision very well.(2)Experimental study on heat transfer performance of open heat source tower.Firstly,an open heat source tower heat pump experimental platform is built,and the measurement methods and experimental steps of the experimental platform equipment and testing instruments are introduced.The selection criteria of circulating solution and packing are described in detail.The heat transfer performance of the open-type heat source tower is analyzed from two aspects of tower body setting and import parameters,through the analysis of heat and mass transfer processes,some suggestions for optimizing the heat transfer performance of open heat source tower are given.(3)The influence of Lewis relation on heat and mass transfer model of open heat source tower in winter is studied.Firstly,the thermodynamic meanings of Lewis relation and Lewis factor are elaborated in detail.Then,the differences of heat transfer performance between the experimental value of Lewis factor and the open heat source tower using Lewis relation are compared and analyzed,and the range of Lewis factor is 0.81~0.98 in the experimental range.