Study On Parameter Optimization Of Expansion Process Of Air Conditioning Heat Exchanger

Tube-fin heat exchanger is the main component of air conditioning heat exchanger,and its forming quality has an important influence on heat exchange effect.In this paper,the expansion quality of the heat exchanger is studied by the tube-fin bonding degree after expansion.According to the problem of incomplete contact between the tube and the fin,the parameter optimization of the expansion process is carried out to improve the tube-fin bonding and heat transfer effect of heat exchanger.First,taking the tube-fin heat exchanger as the research object,the effect of the contact between the tube and the fin after expansion on the tube-fin heat transfer is theoretically studied.Therefore,it is proposed to improve the fitting degree of the tube-fin after expansion from the heat exchanger expansion process.By studying the mechanical state of the tube and the fin under the three stages of the expansion process,the influence of the axial force on the fins on the tube-fin fit is analyzed,and the results that the axial force on the fins are related to the expansion die diameter,the wall thickness of the heat exchange tube and the inner diameter of the fins are obtained.Next,taking bare tube heat exchanger and microgroove tube heat exchanger as research objects,tthe model simplifications are carried out according to the axisymmetric model of bare tube heat exchanger and the rotation-symmetric structure of microgroove tube heat exchanger,and the simplified models are verified respectively.By means of simulation,the factors that affect the bonding of the bare tube heat exchanger and microgroove tube heat exchanger after expansion are studied respectively,and the influence raw of the respective parameters of the expansion die,the tube and the fin on the fitting degree are obtained.In addition,the orthogonal test simulation is designed to obtain the primary and secondary order of the influence factors on the tube-fin fit after the expansion of the two heat exchanger.The optimal parameters of the expansion process of the bare tube heat exchanger are obtained: the expansion die diameter 6.90 mm,bare tube thickness 0.22 mm,the fin inner diameter 7.30 mm and the wall thickness of the fin 0.090 mm.And the optimal process parameters of microgroove tube heat exchanger are obtained: the bottom wall thickness of the microgroove tube 0.23 mm,the micorgroove tooth height 0.20 mm,the micorgroove angle 16°,the fin inner diameter 7.31 mm and the fin thickness 0.105 mm.Last,the optimized parameters of the two heat exchangers are verified from the aspect of heat transfer.On the one hand,the heat transfer simulation of the original model and the optimized model of the two heat exchanger is established.On the other hand,the heat transfer experiment is carried out by setting up the heat transfer experiment platform.The results verify the superiority of the optimal process parameters,which has a guiding significance for actual production.