Judgement and calculation method research of onset of nucleate boiling under tube outside pool boiling condition

Abstract

Abstract Pool boiling is a common phenomenon and widely utilized to realize the heat transfer process in different fields. In advanced nuclear power plant such as the AP1000 passive safety system, pool boiling is also used to fulfil the residual heat removal function through the Passive Residual Heat Removal Heat Exchanger (PRHR HX). The onset of nucleate boiling (ONB) point is one of the key points during heat transfer mechanism changing process. The judgement and predicted method of the ONB under tube outside pool boiling condition is still a difficulty and needs further investigation. In this paper, the heat transfer characteristic of the ONB point is experimentally studied by combining with high speed camera technology. Base on the observing and calculating results, the ONB point is judged. The applicabilities of different ONB point predicting correlations are estimated and an empirical correlation predicting wall superheat degree more accurately is developed.