Paper Title
EFFECT OF COUNTER CURRENT AIRFLOW ON FALLING SPRAY FILMS EVAPORATION OVER HORIZONTAL CIRCULAR TUBES

Abstract
Abstract - The falling spray film evaporative cooling system has shown the advantages of a large flow rate, excellent fouling resistance, and uniform dispersion of water sprays to increase the overall cooling area and enhance heat exchange efficiency. This paper aims to probe the effect of counter-current airflowon the liquid film flow phenomena and thermal outcomes over the horizontal round tubes under impinged sprays at different water flow rates. The present experimental study employs a high-speed camera to grab the optical images of spray film flows tocharacterize the liquid film distribution over the tubes under the state of counter current airflows. The average wall temperature, outlet temperature of spray nozzle and heat flux varied by a programmable DC power supply are measured to resolve the heat transfer coefficient.In effect, the measured total average heat transfer coefficients are 3.79 kW/m2K, 3.92 kW/m2K, and 4.39 kW/m2K at the water flow rates of 3, 5, 7 LPM and a heat flux of 30 kW/m2.The counter current airflow can achieve a increase in heat transfer up to 14.3%. Keywords - Spray Falling Film Evaporation, Film Thickness, Heat Transfer, Counter Current Airflows