GREENHOUSE COOLING USING EARTH-TUBE HEAT EXCHANGER AND EVAPORATIVE COOLING FOR DURING SUMMER SEASON

Abstract

In this research work an attempt has been made to analysis the thermal performance of the earth-tube heat exchanger (ETHE) during summer season of 2012 (June to September). The experimental work was executed in the experimental farm of Faculty of Agriculture, Suez Canal University, Ismailia Governorate, Egypt (Latitude angle of 30.62oN, Longitude angle of 32.27oE, and mean altitude above sea level of 5 m). The ETHE technique was used to utilize the stability of deep soil temperature for reducing the indoor air temperature during the summer season. A computer simulation model has been developed and used based on MATLAB program to determine the depth at which the soil temperature is stabilized. A comparative study between the evaporative cooling system (based on fan-pads system) and the ETHE system was carried out during the summer season to compare weather the two cooling systems differed significantly in the cooling effectiveness to provide and maintain the indoor air temperature within the two greenhouses at the desired level. The obtained data showed that, the depth at which the soil temperature is stabilized was achieved at 3 m deep. The overall thermal efficiency of the ETHE system was 73.85 %. Due to the microclimatic conditions (air temperature and air relative humidity) were at and around the desired level, the growth rate, flowering rate, fruit set rate, and fresh yield of cucumber crop were at high rates and good quality. Data of the computer simulation model of the indoor air and soil temperatures were found to be very closest to that measured.