Processes of Radiation Heat and Evaporation of Droplets and Their Influence on the Shielding Properties of Fire Water Curtains

Abstract

Background . Water curtains are one of effective means of protection against fire thermal radiation. The analysis of the water curtain shielding properties is carried out by means of mathematical model operation. But the process of droplets evaporation as a result of their heating by fire thermal radiation is not considered in the existing mathematical model. Objective . A central objective of the study is the analysis of processes of droplets radiant heating and evaporation, and also their influence on the water curtain shielding properties. Methods . Thermodynamic analysis of the specified processes is made on the basis of the corresponding heat balance equations both for water curtain in general, and for separate droplets. Results . Main results of the study are the numerical calculations and the graphic dependences of the parameters characterizing droplets evaporation for the typical regimes of thermal shielding. For the purpose of verification of the received results their comparison with results of earlier executed experimental studies on evaporation of water droplets at impact of laser radiation of infrared range was executed. It is established that theoretical results in limits of errors are in consent with the experimental results. Conclusions. The conclusion follows from the received results that evaporation of droplets owing to their heating by a fire thermal radiation has no essential impact on the shielding properties of water curtains. This process can be not considered when performing technical calculations.