Cooling of hot ceramic surfaces induced by water sprays in the nucleate boiling regime

An experimental and theoretical research is conducted, focusing on the thermal behavior of hot, non-porous, low-conductivity surfaces during the cooling transient induced by single- and multi-droplet boiling water systems. The research is aimed at modeling the cooling effect induced on a hot solid surface by sprinkler-generated droplets. The long term objective of this study is the construction of a model for the prediction and optimization of the performance of sprinkler-based fire-extinguishment systems. In this paper, the results of a series of experimental tests on single- and multi-droplet boiling systems are presented and discussed. The main objectives of the present study are: a) to investigate experimentally the effect of the boiling onset on the cooling effect induced on the solid surface by the water droplets; b) to measure the evolution of the solid surface temperature during evaporation, with particular attention to the values of minimum, maximum and average temperature; c) to examine the possibility of improving spray cooling efficiencies.