Using Part of Generated Energy by Fermenting Compost in Increasing the Efficiency of Greenhouses Passive Solar Heating System

(Tony asked)

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Abstract

The efficiency of passive solar energy system for heating greenhouses, that consists of four water filled transparent PE tubes and placed on the soil surface in-between the cultivated rows in greenhouses, decreases with the increase of the size of plant canopy as plants grow that shades the tubes. The study aims to increase the efficiency of the heating system using part of the generated energy during composting. The energy from the compost piles was transferred through heat exchangers and closed pumped water system. The piles of compost were placed near the greenhouses of treatment and forced aeration was done by a centrifugal fan. The study was conducted at the Research Station of Protected Cultivation of the GCSAR near Damascus during two successive seasons (2008-2009, 2009-2010). The first season was considered an indicator season. The compost temperature and quality and the effect on tomato yield has been investigated during the first season. The second season results showed that the efficiency of heat collection was improved in the treatment due to the extra heat gain from compost by water circulation by pumps within heat exchangers placed in the compost piles. The average maximum and minimum water temperature in the treatment as compared to the control increased by 1.3 and 1.1176;C, respectively. As a result, the mean maximum and minimum soil temperatures increased by 0.8 and 0.5176;C respectively. Meanwhile, the minimum air temperature increased by 0.8176;C in comparison with the control. The improvement in soil and air temperature in addition to aeration resulted in yield increase of 26% and 23% during the first and second season, respectively. This increase was significant in most of the pickings in the second season. The obtained compost had acceptable quality parameters because forced aeration was used to insure aeration. The economic return was feasible even though the growing season only was for spring cycles. Key Words: Compost, Heat Exchangers, Passive Solar Energy, Protected cultivation, Temperatures, Tomato yield.
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