FEASIBILITY STUDY OF THE USE OF A DEHUMIDIFIER WITH AN EVAPORATIVE COOLER

Abstract

The effectiveness of evaporative cooling in producing comfort conditions depends upon the prevailing weather. General limitations are related to the outdoor wet bulb temperature and relative humidity. In monsoons and in areas where out side wet bulb depression is low, the evaporative cooling becomes ineffective. The present investigation has been in continuation of Phase I study carried out by Harnam Singh at the University of Roorkee(3) Dehumidification of very humid air by silica gel followed by a heat exchanger has been tried, for use with an evaporative cooler. These two attachments have been tested to investigate the improvement obtainable with a typical room air cooler available in the market. Four different arrangements of dehumidifier, viz . a bed type, and box type with three different amounts of filling, have been employed. Air to air heat exchanger with water dropping on the secondary air side, and two water to air heat exchangers, with different number of rows of flat tubes have been tested. The difference in resulting performance has been reported. Although a tendency towards increased thermal relief has been indicated, (v) the improvement is found to be very small. An improved evaporative cooler with incrcas d saturation efficiency should yield greater thermal relief than has been obtained with the evaporative cooler employed in the present investigation. However, on the basis of operating cost, such an arrangement does not appear feasible because: of a very high cost of regeneration of silica gel.