Research of Vacuum Degree Influence on Performance of Vacuum Heat Insulation Oil Pipe

Abstract

In this paper, mathematical model for heat transfer in thermal barrier is established based on the experiment which tested apparent heat conductivity of heat insulation oil pipes. Vacuum degree influence on performance of vacuum heat insulation oil pipe is analyzed by contrasting heat insulation oil pipes in different grades. The main conclusions are as follow. When internal pressure in the thermal barrier is between 0~20Pa or greater than 40Pa, the apparent heat conductivity increases with the pressure. And when internal pressure in the thermal barrier is between 20~40Pa, the apparent heat conductivity decreases with the pressure in volatility. When internal pressure in the thermal barrier is between 30~40Pa, the apparent heat conductivity of heat insulation oil pipe is lesser.