Research On The Heat Transfer Performance Of The Micro-channel Separated Heat Pipe

The separate heat pipe is a kind of based on conventional h eat pipe technology.It can be highly efficient heat transfer of new type heat transfer element.its working principle is in the separated arrangement of evaporator and condenser to form the height difference,and refrigerant relies on gravity to make it flow in pipe.Micro-channel generally refers to the equivalent diameter 3 mm the following passage,and in the air conditioning industry,micro-channel heat exchangers has the following advantages:low pressure drop,light quality,low refeigerant charge and high heat transfer performance.So micro-channel heat exchangers is been taken as the evaporator and the condenser,which can strengthen micro-channel heat transfer effect and improve the heat transfer efficiency of the whole system by combining advantages of both micro channel heat exchangers and the separated type heat pipe.Fristly,the effect of the filling ratio on the heat transfer rate,EER,pressure and temperature of the refrigerant and mass flow rate are investigated by experiment in enthalpy difference laboratory.The results show that the optimal filling ratio of is 74.5%-113.2%,and the maximum heat transfer rate and EER are 3.89 kW and 11.3.Under the different working conditions,the change of outdoor temperature can affect the performance of heat exchange system.The results show that the increase of temperature difference between indoor and outdoor can improve heat transfer performance from 1.89 kW to 7.59 kW.The investigate is in a growth trend.The effect of different air volume on the heat transfer performance is studied.The result shows that the larger the air volume can make improve the heat transfer rate and EER,but the optimal filling ratio is still 74.5%?113.2%.Secondly,the micro-channel steady-state heat transfer calculation model is established in MATLAB.The separated type heat pipe system is divided into micro-channel evaporator steady-state heat transfer model,the micro-channel condenser steady-state heat transfer model and calculation model of the steady state micro-channel heat insulation section.The model can research the effect of different laboratory on the heat transfer performance of the system and the flow mechanism.The results show that the optimal filling ratio of the simulate is same as the optimal filling ratio of the experiment,and the relative error of the refrigerant pressures is less than 1%.In addition,the maximum relative error of the refrigerant temperatures is 6.8%.As to the maximum cooling capacity,the relative error of the simulation and experiment is 1.8%.These errors are all within a reasonable range,so the accuracy and feasibility of the model was verified.Finally,by the steady state model,the effect of indoor and outdoor temperature,air volume on the heat transfer performance and flow characteristic were calculated.Based on the simulation,the influence of structure parameters of micro-channel heat exchanger such as fin height,fin pitch,flat tube,louver pitch and louver angle of the heat exchanger on the heat transfer performance and flow resistance are analyzed,which can give a reference to the optimization design of the system.