Calculation specifics in the study of solar greenhouses with thermal energy accumulator in mind

Abstract

The paper presents a simplified thermal model that allows estimating heat losses taking into account the main parameters: the surface of the greenhouse - a transparent fence, the bottom of the greenhouse - soil and the ratio of the design of greenhouses. A simplified thermal diagram of the greenhouse heat transfer has been compiled and, on the basis of the simplified thermal diagram, heat losses through the transparent enclosure, through the bottom, soil and structural ratios have been determined by calculation. Calculations show that with total solar radiation, 620 W/m2, heat loss through the surface of a transparent fence is 508 W/m2, in percentage terms it is 82%. At the same time, through the bottom (ground) 58 W / m2, in percentage terms they are 9%, the total heat loss is 566 W / m2, in percentage terms they are 91%. To reduce heat loss through the transparent enclosure, it is recommended to use more innovative materials, such as ceramic film with improved thermal insulation properties or low iron glass, extra clear glass, double-layer transparent enclosure, and it is also recommended to enclose one side of the greenhouse with a thermal insulation wall. According to calculations, in order to reduce heat losses through the bottom of the greenhouse, we recommend making a special deepening in the soil, since at large soil depths, a slow spread of soil temperature is observed, which will also lead to the least heat loss. To reduce heat losses through the bottom of the greenhouse, we recommend using thermal energy accumulators in the ground. Estimation of heat losses makes it possible to determine the required amount of heat loss through the surface and bottom of the greenhouse and, based on these calculations, carry out research work to reduce them.