Determination of heat transfer coefficients for complex spray cooling arrangements

Abstract

Numerical simulation of quenching by air-water spray cooling requires an accurate knowledge of the spray heat transfer coefficients (HTCs). In this work, a novel method of heat transfer determination is presented that takes lacking aspects of prior determination methods into account. The temperature trends during cooling of a thin-walled tube are used in an optimisation calculation based on a numerical model of the setup to determine the HTCs. It is shown that higher inlet pressures lead to higher heat transfers and that the heat transfer between two spray nozzles increases with decreasing nozzle to nozzle distance. However, for some cases, adjacent sprays can lead to decreasing HTCs. The amount of nozzles in circumferential direction had an overproportioned effect on the heat transfer in the film boiling regime. Verifications generally show a good agreement of measured with computed temperature trends based on the calculated HTCs.