Research On Simulation Of Air-Conditioning Fin-Tube Heat Exchanger Forming

As a kind of compact heat exchanger, fin-tube heat exchanger is widely used in air-condition and refrigeration industry. Because of the technique development in air-condition and refrigeration industry,as well as stricter regualtions on energy saving and environmental protection,improving heat transfer coefficient of the heat exchanger unit has been becoming an essential means to enhance the heat transfer performance of whole heat exchanger system and balance low performance of alternative refrigerants. Fin-tube expand-joint forming and heat exchanger bending are key forming techniques in manufacutre of fin-tube heat exchanger,which are greatly related to the capability and reliability of heat exchanger. Nowadays,the application of new technologies, like grooved copper tube forming, and demand of high efficiency in mass production,brings many challenges to the forming process design of the fin-tube heat exchanger.In this thesis,the expand-joint forming process of fin-tube heat exchanger is studied by using the finite element method. 2D and 3D FE models of the forming process are established based on the inner grooved tube and L shape fin. The formability parameters,such as driving force,tube parameters and the contact status and contact pressure between the fin and tube are numerically studied to find the factors which influence the forming quality.Based on the wave shape fin which is widely used in air-conditioning heat exchanger,the FE model of multilayer bending process is established to study bending process of fin-tube heat exchanger. Through the research the important forming parameters in the heat exchanger bending process,the reason for fins crash are found. Futhermore, forming process parameters of the fin-tube heat exchanger are optimized. To improve the and contact effect and forming quality,the influence of different mandrel shapes on tube forming process is studied. Meanwhile, fin shape modelled by spline curves is optimized to get an optimal shape to decrease the contact gap, and then increase the heat transfer coefficient. The influence of the different structures of the bending die,the urethane sheet and changes of the boundary conditions on the heat exchanger bending process are also analyzed. Some suggestions to improve bending process are given.Experiments are carried out to validate the simulation result. Good agreement between the simulation and experimental results is obtained. It can be concluded that the FE model of the fin-tube heat exchanger forming process in the thesis can reflect the actual production well and provide guide for practical production.