Process intensification in a cross-flow rotating packed bed for evaporative cooling of water

Abstract

Cooling towers are essential devices in any chemical processing industry, air conditioning, petrochemicals, power generation units among others where an enormous amount of waste heat is generated continuously. To cool the equipment, water is generally considered a suitable coolant as it is easily available, non-degrading in nature and can be reused multiple times, and also has a high heat capacity. In this experimental study, the performance evaluation of a packed bed contactor under centrifugal field is done for evaporative cooling of water by an unsaturated gaseous stream wherein the two phases come in contact in a cross-current mode. Rotating packed beds (RPB) are acclaimed Higee (high gravity) devices utilized in process intensification. Here, the action of terrestrial gravity (as in conventional devices) is altered by strong centrifugal acceleration (∼100–1000g). Higee devices have a great impact on the mass transfer rates leading to a drastic reduction in the equipment volume. The performance evaluation is done in terms of evaporation rate of water and thermal efficiency of the Higee contactor and the effect of operating parameters were examined as well. With increase in the gas flow rate and rotational speed there is an increase in the evaporation rate from 0.012 - 0.034 kg/min. There is a minute reduction in the evaporation rate with the increase in liquid flow rate. The maximum and minimum values of thermal efficiency of the contactor in the study are 0.20 and 0.37 respectively. The study depicted that rotating packed beds are cost and time effective and technically feasible for evaporative cooling of water.