Thermographic investigation of water droplet boiling on hot ceramic surfaces

An experimental research is conducted, focusing on the thermal behavior of hot, non-porous, ceramic surfaces during the cooling transient induced by single- and multi-droplet boiling water systems. The research is aimed at modeling the extinguishment of a solid fuel fire by sprinkler-generated droplets. The long term objective of this study is the construction of a model for the prediction and optimization of sprinkler-based extinguishment systems performance. In this paper, the results of a series of experimental tests on single- and multi-droplet boiling systems are presented and discussed. In order to get more insight into the solid surface temperature transients induced by dropwise evaporation and boiling, the test materials have been chosen within the category of low thermal conductivity substances (1 to 5 W m-1 °C-1), so that a relevant and well-measurable cooling effect is observed. The dropwise cooling transients are monitored by the non-intrusive method of infrared thermography, and the potentialities of this approach are stressed out.