الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
An experimental gableevenspan polyethylene greenhouse was built and installed, in order to study and investigate the possibility of utilizing a passive solar energy system for warming the environment of cucumber crop. It was used to minimize the fluctuation of inside air temperatures between the daylight and night times. Two water tubes made of polyethylene sheet each having contained 0.353 m3 water were vertically moved at sunrise to hung up on the roof of greenhouse, in order to maximize the solar radiation flux incident on them. At sunset they were moved down to situate between the rows of cucumber plants. Under clear sky conditions, the measured solar radiation flux incident outside and inside the greenhouse varied from time to time, from day to another, and during the month according to the sky cover (clouds), solar altitude angle, and solar incident angle. The ambient air temperature inside the greenhouse at night was greater than that outside the greenhouse on average by 3.1 (R@(BC, due to the heat energy supplied by the passive energy system in addition to the heat gained from the floor, plants and cover. The water temperature in the plastic tubes at night time was on the average greater than the air temperature inside the greenhouse by 4.9 (R@(BC. The measured water temperature inside the two plastic tubes were validated with the computed using air energy balance during daylight time. The greatest amount of heat energy supplied by the heat distributing system using passive energy system was achieved on January when the temperature difference between water and interior ambient air was 6.49 (R@(BC. On the other hand, the lowest amount of heat energy supplied occurred on May when the temperature difference was 2.26 (R@(BC. The difference between the total heat load added to the greenhouse at night time and the total heat losses for each month during this research work was small. The measured water temperature inside the two plastic tubes at night time were validated. The daily average effectiveness of the heat distributing system using passive energy system during the heating season was 47.58%. The southern row gave the greatest number of leaves because it was exposed to more solar radiation during daylight, and faced the hot sky at night time. The rate of vegetative growth was satisfied and maintained the same throughout the growing season. This was due to the heat energy added from the water tubes particularly at night time during winter season.