Abstract: Net heat absorbed or lost by the lower convective layer of an experimental solar pond in different days and months was studied during the period of 126 days in 1999. Internal energy level of lower convective layer increases via absorbing solar energy, and decreases due to heat loss into the ground and the walls of the pond. In order to estimate net heat absorbed in that layer, initially internal energy difference was calculated in the layer during consecutive days in the whole period. The general trend obtained for the daily changes of net heat absorbed or lost by the lower convective layer was identical in per unit mass and per unit area of the pond. Because intensity effects of temperature variations in lower convective layer over time were more important than the effects of changes in lower convective layer elevation, density and specific heat of the layer on the total trend of heat absorbed per unit area. During the study period, net heat absorption occurred for 60 days; net heat loss happened for 56 days and there was no net heat absorption or loss for 10 days or its value was very insignificant. The maximum values of net heat absorbed per unit mass and per unit surface area, were corresponded to the 1th May and were 14.3 kJ/kg and 14.3 MJ/m2 respectively. The maximum values of net heat lost per unit mass and per unit surface area, were attributed to the 20th May and were equal to 04.1 kJ/kg and 34.. MJ/m2 respectively. The average daily values for the duration of heat absorption were close to the average daily values of heat loss per unit mass and per unit surface area and thus, the average daily values for the total period were positive and equal to 14130 kJ/kg and 0.017 MJ/m2 but insignificant. It was observed that monthly value of the net heat was positive (net heat absorption) in May and June but negative (net heat loss) in July and August as well as the amounts of average daily net heat were equal to 0.20 MJ/m2 and -0.16 MJ/m2 in June and July respectively.
Keywords: Solar Pond, Lower Convective Zone, Heat Absorption, Heat Loss
Volume 1, Issue 1, 2014