Abstract:
The objective of this research was to study heat transfer in fertile soil for
seedlings using solar energy to heat water for curbing the growth of microorganisms in
soil and cultivate seedlings.
The efficiency of various solar collectors including an asymmetric compound
parabolic concentrator, a heat pipe evacuated tube solar collector, and a flat plate solar
collector were determined. Then, the solar collectors were connected in a series circuit
to create hot water system. Four arranged patterns of solar collectors were studied. The
pattern that could produce the highest water temperature was used to drip hot water
into the soil to study heat transfer in the seedling soil.
The results showed that the efficiency of the asymmetric compound parabolic
concentrator, the heat pipe evacuated tube solar collector, and the flat plate solar
collector were 79.45%, 72.25%, and 21.53%, respectively. When the three solar
collectors were connected in a series circuit and produced hot water from solar energy
system, the ambient temperature was heated with a large asymmetric compound
concentrator to increase the water temperature. The heated water was put into a flat
plate solar collector that placed between a large and a small asymmetric compound
concentrator to receive solar energy. Then, the water produced with the flat plate solar
collector was put into the heat pipe and evacuated tube solar collector to increase the
water temperature. It was found that the last pattern could produce hot water of 100
oC at the flow rate of 0.004 kg/s with solar radiation of 991 W/m2. As the result, the
temperature of the fertile soil for seedlings could rise at the depth level of 0, 5, 10, 15,
20, 25, and 30 cm, respectively. The water temperature was at 75.5 oC, 75.3 oC, 75.1 oC,
74.9 oC, 74.7 oC, 74.5 oC, and 74.1 oC, respectively. The rise of water temperature could
curb R. solanacearum which caused the plant diseases.