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Innovative fin arrangements were proposed to enhance the thermal performance of latent heat storage units. The enthalpy-porosity approach was employed to optimize the fin distribution and predict the transient melting behaviors of N-octadecane. The unit with horizontal fins of uniform length was set as the base condition for comparison. It was found that the dead space of heat transfer and melting due to natural convection was not effectively eliminated by the conventional fin set. The region persisted at the bottom of the unit until the end of the melting process. In light of these observations, the fins were repositioned and resized. Three alternative fin configurations were proposed and evaluated: angled fins, asymmetrically located fins, and stepped fins. Results illustrated that fin structures significantly influenced the heat transfer characteristics and melting behaviors of latent heat storage units. Generally, greater enhancements were attained with downward angles and downward offset distances. The downward angle −20°led to an accelerated melting rate of 18.3 % compared to the base condition. In case 9, where the fins were moved down by 12 mm, the heat transfer enhancement ratio reached 32.5 %. However, introducing inhomogeneity in the fin length had only a minimal impact on the melting process. • Non-uniformity in heat transfer due to natural convection decreases the overall PCM melting. • Novel fin arrangements are employed in this paper to improve the PCM melting as well as heat transfer. • Fins with downward angle and downward offset can substantially increase the thermal energy storage rate. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]