Thermal Radiation Analysis for Single Panel Cryopump Application

Abstract

The world is facing energy crisis as various conventional energy sources are on the verge of depletion. This energy crisis demands for more reliable and long-lasting technology to generate power. Presently an extensive work is carried out to develop fusion technology based on plasma con nement for power generation. The power generated with reaction in plasma depends upon the amount of vacuum created in the con ned space. The need for high vacuum is achieved by cryopumps installed in the system. Cryopumps are used in many application where high to ultrahigh vacuum are needed. The principle working of cryopumping is to remove gas from the system, i.e generating vacuum, by condensing on a cold surface (i.e Cryopanel). The e ectiveness of cryopump also the performance of the overall system depend upon the fraction of molecules sticking to the surface of cryopanel in the cryopumps. It become utmost important to maintain the cold surface of the cryopanel at very low temperature in order to improve the e ectiveness of cryopump. It is a challenge for designer and analyst to work with such ultrahigh vacuum and low temperature application in studying the various parameter a ecting the performance of cryopumps at ground level and under extreme environmental condition. The low temperature on the cryopanel is attained by owing liquid helium (boiling point 4.2 K) into it. The rise in the temperature of the cryopanel leads to desorption of gas molecules on the surface which decreases the pumping speed as well as amount of energy generated in plasma fusion process. Cryopumps, required for D-T reaction and plasma sustainability, are operated at very low temperature (up to 4 °K) and in ultrahigh vacuum range (below 10-6 Pa up to 10-12 Pa), the possibility of heat transfer by convection is negligible while conduction through support structure and supply line are minimized by using low conductivity material. The only cause of heat transfer on cryopanel is through radiation. Present work study the e ect of radiation heat transfer on cryopanel, as a critical component to be evaluated for heat load. It includes theoretical and analytical approach to calculate radiation heat load on cryopanel. View factor evaluation is important in radiation heat transfer. View factor calculation between surfaces of baffl es and cryopanel are evaluated through FEA and value of heat load on cryopanel is calculated theoretically. The project work includes study of radiation heat transfer on cryopanel through radiation shield and ba es and calculate heat load variation on the panel surface at various points. The Finite element analysis software ANSYS is used to carrying out this project. It is the software that has been keenly programmed with many sorts of problem in thermal analysis. ANSYS gives more accurate and better solution for the actual geometry in existence.