不同热边界条件下板翅式换热器轴向导热对换热的影响

Based on MATLAB program and by implementing the distributed parameter method, the 2-D model of reverse-flow plate fin heat exchanger(PFHE) was constructed. The numerical results were compared with the experimental results in a multi-stream PFHE used in liquefier in Claude cycle, and the numerical results were in good agreement with the experimental results. The effect of the axial conduction on heat transfer performance of PFHE was investigated, and it was observed that the effectiveness of PFHE considering axial conduction decreased by 21.8%, compared with that without considering axial conduction. Moreover, the influence of the adiabatic boundary condition on the cold and hot ends of separating plate of PFHE was transferred to the inner domain of PFHE by axial conduction effect, which resulted in the fluid temperature distortion in near-inlet domain. When the boundary conditions of constant wall temperature or constant heat flux were adopted on hot and cold ends of separating plate respectively, the fluid temperature distortion in near-inlet domain almost disappeared. When considering axial heat conduction, compared with the adiabatic boundary conditions at both ends of the partition, the effectiveness of the constant wall temperature boundary conditions increases by 35.8%(ε_c) and 31.7%(ε_h), and the effectiveness of the constant heat flow boundary conditions increases by 22.8%(ε).