Numerical Simulation Of Heat Transfer Enhancement In The Heating Pipe Of Deicing Fluid

The rapid deicing fluid heating system is the kernel equipment of civil aircraft ground deicing system,which is of great importance to safety and efficiency of aeronautical service under icy condition.However,the domestic heating system designed has not been as efficient as those aboard when large flow of deicing fluid is heated.In this paper,the helically coiled tube,the main heat exchanger in the system,is optimized to enhance the heat transfer,in order to improve the efficiency of the heating system.The study of heat transfer enhancement is mainly on straight pipes,with ideal fluid as working medium.In this paper,the heat transfer and flow characteristics in helically coiled tube are studied in consideration of the viscosity of working medium.Smooth helically coiled tube with inner diameter D is optimized to transverse corrugation helically coiled tube(TCHC),where equal-pitch ring-ribs are convex on the inner wall.The influence of the ring-ribs' geometric parameters on heat transfer is studied by control variable method.Referring to the study of the heat transfer of straight tube with ribs,the ring-ribs parameters are selected with depth in the 0.025D~0.2D and width in 0.3D~2.0D.Deicing fluid is an ethylene-glycol-based mixture of highly viscosity.Glycol is chosen as work medium to simplify the heat transfer.The heat transfer of glycol is simulated by numerical method in smooth helically coiled tube and TCHCs with different parameters.The Field synergy principle is applied to analyze the complex heat transfer and flow characteristics.The results indicate that TCHC shows better heat performance than the helically coiled tube,which means that TCHC achieves heat transfer enhancement.TCHC performs well in the heat transfer when the depth of the ring-ribs is in the range of 0.05D~0.075 D and the width is in the range of 0.4D~0.5D in condition that the pitch of ring-ribs is fixed.According to Field synergy principle,the fluid radial velocity component increases with the augmentation of the ring-ribs' depth,which coordinates the velocity field and the temperature gradient field.Then,the heat transfer is enhanced.The heat transfer parameters varying with the change of ring-ribs' width is not obvious because the width has little effect on the velocity.Compared with the width,the depth of ring-ribs has greater impact on the heat transfer of thefluid.The heat transfer and flow characteristics are studied by numerical simulation in helically coiled tube and its optimized model.The influence of the geometric parameters of the ring-ribs is analyzed.The optimized model is proved to be effective with highly viscous fluid.Meanwhile,the preferred range of parameters is obtained.The research of this subject provides the theoretical reference for the design of the rapid deicing fluid heating system.