Heat Transfer Efficiency While Cooling with a Water Spray, Air-Assisted Water Spray and Water Jet Under Boiling and Single-Phase Forced Convection Conditions

The main purpose of this paper was to determine and compare the boundary conditions of heat transfer on the cooled surface of a cylindrical sensor made of Inconel 600 alloy while cooling with a water jet, water spray and air-assisted water spray under high-temperature conditions. The inverse method for the heat conduction equation was used to determine the boundary conditions. Experimental tests were carried out, including temperature measurements at several points inside the cylinder while cooling with all the tested systems from a temperature of 900 °C for three values of water pressure: 0.05 MPa, 0.1 MPa and 0.2 MPa. Temperature measurements were used as the input data to identify the heat transfer boundary conditions. The temperature field of the axially symmetric sensor was determined using the finite element method. The boundary conditions were determined as average values of the heat transfer coefficient and heat flux and local values of the heat transfer coefficient. A comparison of the amount of thermal energy dissipating from the sensor surface as a result of boiling and a forced single-phase convection is also presented in the paper. The highest uniformity of cooling was obtained during air-assisted water spray-cooling.