THERMAL PERFORMANCE FOR GREENHOUSE HEATING BY USING EARTH-TUBE HEAT EXCHANGER DURING WINTER SEASON

Abstract

In this research work an attempt has been made to analysis the thermal performance of the earth-tube heat exchanger (ETHE) during winter season of 2012-2013 (December to March). 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 worming the indoor air of greenhouse cucumber during winter season, and 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. 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 during winter season (heating process) was 72.90 %. 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.