Pressure Drop Characteristics of Slit-Type Heat Exchanger
A slit-type heat exchanger offers several advantages to the design of cryocoolers; it can accommodate various configurations either in a straight or tapered shape and involves no thermal contact resistance problems, which are often encountered in a mesh-type heat exchanger. The needed heat path in the radial direction of the heat exchanger of a large-scale and high-power cryocooler is especially favorable. Our focus here is on the measurement and analysis of the pressure drop characteristics of a slit-type heat exchanger. First, measurement of overall pressure drop is considered under steady-flow conditions. The analyzed parameters of the heat exchanger configuration include: 1) size of slit; 2) number of slits; and 3) angle of slit. Second, using the pressure boundary conditions obtained from the experiments, CFD (Computational Fluid Dynamics) was carried out to reproduce the experimental data. Using the CFD calculations, the entrance and exit losses of the pressure were carefully examined and identified. These results can divide the overall pressure drop into the entrance, exit, and tapered channel losses. Finally, we conclude that the pressure drop characteristics under steady flow conditions can be used for conditions of oscillating flow. The presented results should help one design an optimum regenerative cryocooler with slit-type heat exchangers.