THE EFFECT OF DISSOLVED GAS ON BOILING INCIPIENCE AND SUBCOOLED BOILING HEAT TRANSFER

摘要

The knowledge of heat transfer characteristics in the presence of dissolved gas is of importance in thermal hydraulic design of integral reactor with a self-pressurizer including N_2 which can be liberated during postulated accidents. This experimental study investigated the dissolved gas effects on the onset of nucleate boiling and the subcooled boiling heat transfer under natural convection in a closed test loop scaled for a integral reactor. Steady state experiments were conducted at pressures of 1, 3, 5, 10 bar with increasing the heat flux for both conditions of gas-saturated and degassed. A single-phase natural convection heat transfer correlation was suggested, and the subcooled boiling heat transfer coefficients were increased up to 37% due to the dissolved gas. In the transient experiments of decompression, the dissolved gas effects were investigated with measuring the temperatures of local position when the system pressure drops from 10 to 1 bar within 400 seconds.