F105 Flow Boiling Heat Transfer and Wall Temperature Distributions of Helically Coiled Steam Generator Heated in Oil Bath(Heat Exchanger)

Abstract

A scale model experiment of the flow boiling heat transfer to water in a helically coiled tube submerged in a high temperature oil bath was conducted to clarify the heat transfer characteristics of the steam generator of LMFBR. The external and internal tube wall temperatures were measured under low quality conditions and heat fluxes across the tube wall were calculated from their difference. One dimensional thermal conduction model was applied to evaluate the heat transfer coefficients at the external and internal tube wall and their time variations. The results show that the heat flux change is caused by the heat capacity of the tube and its temporal behavior is quite different from the wall temperatures. The periodic change of the heat transfer may cause the local dry-out and peculiar variations of the wall temperatures and the heat flux.