Study on Basic Analysis Method of Critical Heat Flux in Energy System

Abstract

The parameters of molten salt heat storage power generation system are continuously improved. The boiling crisis caused by deterioration of heat transfer in such system is studied and the basic mechanism and influencing factors are explored. In traditional theory the dry area of the bubbles are the cause of sudden overburning. In this paper the physical phenomenon is simulated by a variable heat convection boundary condition. Based on Fluent, four factors, including growth rate of dry area, size of dry area, size of pipe and shape of pipe, are simulated and analysed numerically to figure out what effect they have on wall temperature rise. The calculation results show that if final size of dry area is consistent, the dry area’s expansion rate will have little influence on wall temperature because time for temperature to rise is much more than that for dry area to grow; The highest temperature rise is directly dependent on the size of dry area, and is also affected by the size of pipe, which is related to volume heat flux; Corner of square pipe is more likely to face the boiling crisis than centre region. In order to burn the pipe wall, there must be a large area of heat transfer deterioration lasting for quite a long time, so the most cases of the wall damage is due to thermal stress instead of traditional statement “burning”. This method provides a new analytical perspective and has guiding significance for experiment and theoretical analysis in the next research plan.