INFLUENCE OF WATER TEMPERATURE ON DROPLET SIZE DISTRIBUTION OF HIGH-PRESSURE WATER MIST NOZZLES

Temperature affects the number of water properties. Density, specific heat capacity, surface tension and more change with temperature. The size of the water droplets has strong impact on the shielding of radiant heat or the ability to extinguish and suppress fires. Determining the droplet size distribution of water mist is used in wide range of industries, in fire protections, spray technology, pharmaceuticals or automotive industry. The work deals with the measurement of the droplet size distribution of eight selected nozzles at different temperatures using the laser diffraction method. The selected nozzles are designed for use in fire protection to extinguish and suppress fires. Measurements were taken at the distance of 12.5 cm from the nozzle in the centre of the mist stream. The water source temperatures chosen for the measurements were 25, 40, 55 and 80 degrees Celsius. The purpose of the work was to determine the effect of temperature on the change in Sauter mean diameter and particle size distribution at a working pressure of 70 bar. For the six measured nozzles, a decrease in Sauter mean diameter with increasing temperature was observed. For the two measured nozzles the result was the opposite. The particle size distribution of the four measured nozzles varied significantly at different temperatures.