In-Situ Evolution of Heat and Mass Transfer Phenomena and Evaporative Water Losses of Three Agro-Waste Evaporative Cooling Pads: An Experimental and Modeling Study

摘要

Utilization of evaporative cooling to condition rooms for increased productivity of farm animals is very common. The major challenge in adopting this technology in sub-Saharan Africa is the availability of cheap and effective cooling pads to provide the desired room condition. In this research, prediction of heat and mass transfer coefficient and evaporation losses of three agro based evaporative cooling pads based on mass density difference of the process fluid and binary diffusivity coefficient at the exit air temperature was established. The study was performed for wood charcoal, jut and palm fruit fiber as evaporative cooling pad materials. The dynamic performance of these three agro based cooling pads was also investigated in real time under a very fluid dry environment with a constantly intruding moist wind from southern Atlantic Ocean. The experimental results showed that mass transfer coefficient for the three products varied from 1.969 x 10(-2) to 1.503 x 10(-1) m/s depending on the product and the applied air flow rate. Similarly, the heat transfer coefficient ranged from 19.79 to 151.1 W/m(2) K. Periodic variation in evaporative effectiveness was observed with highest value occurring at the lowest inlet air velocity of 1.13 m/s for jute fiber. Comparison of the modeling results between Halasz, and the indicative rule of thumb used by Baltimore Aircoil was favorable to Halasz model with a coefficient of variation ranging from 0 to 3.06 x 10(-7) and a correlation coefficient of about 0.98. the second model has shown a deviation from experimental results that can reach 45% under particular conditions.