Identification of the average and local boundary condition of heat transfer during cooling with a water spray under surface boiling

The study determined the local and average heat transfer coefficient and the heat flux on the surface of a cylinder cooled with a water nozzle. The inverse method was used to identify the heat transfer coefficient. An objective function was defined to determine the distance between the measured and calculated temperatures. Two models describing the heat transfer coefficient on the cooled surface were considered. The first model described changes in the heat transfer coefficient as a function of the sample radius and cooling time, and the second one assumed the dependence of the heat transfer coefficient solely on time. Numerical simulations showed significant differences in the determined heat transfer coefficients depending on the adopted model of the boundary condition. The performed tests included experimental temperature measurements at selected points of the sensor, numerical simulations of temperature changes, and the inverse solution.