Experimental study on thermal performance of high absorption latent heat storage plate (LHSP) in greenhouse

Abstract

Phase change material (PCM) can effectively reduce temperature fluctuations in greenhouses and increase crop yields. Plastic greenhouses are a major form of facility agriculture in southern China, and there are no walls in it. Therefore, how to combine plastic greenhouses with PCM has become research hotspot. A new type of high absorption latent heat storage plate (LHSP) was proposed. That is to lay PCM plates on the north side of the plastic greenhouse vertically. To enhance solar energy utilization and reduce heat loss, solar high absorption and thermal insulation layer were respectively placed on the sunny side and shady side. Two greenhouses were constructed and LHSP was placed in one greenhouse as Case 1. After that, a solar high absorption film and thermal insulation layer were attached to the sunny side and the shady side as Case 2 and Case 3. The average air temperature of two greenhouses and the thermal performance of LHSP were compared under three cases. Results showed that, in Case 1, the LHSP can raise the average air temperature inside the greenhouse by 1.8–2.9 °C during the night. in Case 2 and 3, the average air temperature had a stable improvement of 1.6–2.2 °C and 1.8–2.1 °C respectively at night. Besides, in Case 2, the heat storage of LHSP on sunny side had increased by 26.2%. In Case 3, the total average heat loss of LHSP was reduced by 21.5% and the average heat release from sunny side had risen by up to 39.7%. The high absorption latent heat storage plate showed excellent thermal performance.