Experimental study on the correlation of subcooled boiling flow in horizontal tubes

Abstract

Subcooled boiling is the most effective form of heat exchange in the water jacket of the cylinder head. Chen's model is the most widely used correlation for predicting boiling heat transfer, but the selection of the correlation for the nucleate boiling is controversial. The work of this paper is to simulate the heat transfer process in the water jacket of the cylinder head with a horizontal rectangular channel that is heated on one side. Using the coolant flow velocity, inlet temperature and system pressure as variables, the heat flux and heat transfer coefficient were obtained. The results show that the increase of the coolant flow velocity can effectively promote the convection heat transfer, and the change of inlet temperature and system pressure will affect the occurrence of nucleate boiling. However, the Chen?s model predictions doesn?t fit well with the experimental data. Four nucleate boiling correlations were selected to replace Chen's model nucleate boiling correlation. The correlation proposed by Pioro coincides best with the experimental data. The mean error after correction is 18.2%.

Low temperature simulation of ammonia refrigeration based on dissipative molecular dynamics

“…Although this improves the evaporator heat exchange, but the oil layer caused by lubricant obstruction heat exchange problem has not been fundamentally resolved. At the same time, most scholars focus on the problem of oil retention in evaporators, mainly study oil ammonia separators, but oil ammonia separation the refrigeration unit is too complex, installation, maintenance and service life are problems [9]. To solve the problem of evaporator oil retention, the most fundamental is to understand the mechanism of oil/ammonia in the evaporator interaction and its flow pattern.…”