Heat Transfers Coefficients of Directly and Indirectly Cooled Component Areas during Air-Water Spray Cooling

For the determination of heat transfer coefficients in air-water spray cooling, two methods are presented that are capable of characterizing multi-nozzle cooling set-ups. The methods are based on the quenching of thin-walled tubes or massive cylinders on which cooling curves are recorded at given positions with thermocouples. The temperature dependent heat transfer coefficients were calculated by an inverse calculation and the measured temperature-time-curves could be reproduced with these data in numerical cooling simulations. Next, the determined heat transfer coefficients were used for the calculation of an air-water-spray quenching process of a forging part with more challenging geometry. The calculated results were compared with thermocouple measurements. Different calculation variants for the heat transfer on component surfaces not directly exposed to the air-water spray are shown and discussed. ◼