Comparison Of Experiment and Simulation Of Thermal Hydraulic Of Radiation Shield Of Cryosorption Cryopump

Abstract

Cryopumps belong to the class of entrapment or capture vacuum pumps which retain gas molecules by sorption and/or condensation on its internal surfaces. Thus, the performance of cryopump is governed by the interplay of these two pumping mechanisms. The cryopump consist of cryopanels as pumping surfaces. The pumping surfaces or the cryopanels can be arranged circularly and suspended from the header. These cryopanels are enclosed by 80K cylindrical shield. Baffles can be installed to prevent the cryopanels from the high temperature radiation from the pump inlet. Baffles are cooled by 80K gaseous helium. The 80K cylindrical shields can be enclosed by the pump housing. The paper describes study of temperature distribution over radiation shield plate of 0.5xO.5 m, which is made up of SS 316L. Thermal hydraulic analysis was performed for flow of liquid nitrogen at 80 K and liquid Helium at 4.5 K. The results were compared with the theoretical calculations. To study pressure drop and heat -transfer rate an experiment was carried out by flowing hot water through the radiationshield. The heat flow images c::-ptured by the infrared (IR) camera.