Experimental investigation and theoretical prediction of the multistage reciprocating evaporative cooler

Present work comprises the fabrication of a multistage reciprocating humidifier where four Celdek 7090 packings are arranged at different positions run by a motor connected to a cam follower. Packing dips in the water and comes in contact with air in cross flow direction in a duct. Air velocities and camshaft speeds are varied to evaluate the performance parameters such as outlet dry bulb temperature, outlet specific humidity, evaporation rate, coefficient of performance, cooling effect and humidification efficiency. A theoretical model is constructed to predict the performance of the multistage dynamic humidifier. Stage-wise performance is also determined to analyse the influence of number of stages on the cooler performance. The system gave a maximum evaporation rate, energy conversion factor, humidification efficiency equal to 1.864 g/s, 4.84, and 72.62 %. The predicted performance parameters for various conditions are found to be in agreement with the experimental results. Experimental and empirical results are close to each other with a maximum deviation of 2.1 %, 2.4 %, 8.3 % and 8.5 % for exit air temperature, exit humidity ratio, saturation efficiency and energy conversion factor respectively for various tested air flow rates. Stage wise performance revealed that higher number of stages will drastically deteriorate the performance and simultaneously increase the energy consumption.