Heat Transfer of a Single-Phase Natural Circulation Loop With Heating and Cooling Fluids

Abstract

In present work, a one-dimensional simplified mathematic model of a single-phase natural circulation loop with heating and cooling fluids at steady state is presented. Water is used as the working fluid and the secondary fluid in the loop. A numerical verification was performed using the case with a constant heat flux condition in the heater, the results of which show the good agreement with the experiment results published in the literature. Results show that the steady state Reynolds number, the modified Grashof number and the heat transfer rate increase with the increase of driven temperature difference. And the steady state Reynolds number increases with the increase of the loop diameter and the value of the Reynolds number ranges from 10 to 100, which means the laminar flow regime in the SPNCL. The effect of loop diameter on modified the Grashof number is relatively weak at higher driven temperature difference. For heat transfer rate, it increases with the increase of loop diameter through there is a decrease in the temperature difference ΔTr.