Analysis of heat transfer properties of hollow block wall filled by different materials in solar greenhouse

In the present study, the volumetric thermal capacity and thermal conductivity of hollow block wall were changed by filling soil and perlite in the cavities to improve wall thermal performance. The results show that filling soil or perlite in the cavities of hollow blocks is a feasible way of improving the thermal performance of north wall of Chinese solar greenhouses. Filling hollow blocks with soil increases the thermal capacity of wall, and more heat can be stored. Filling hollow blocks with perlite increases the thermal resistance of north wall so less heat is lost. Then, two layered composite walls (wall HB-2P4S and HB-4P2S) were designed and their performance was compared. Model simulation and experimental results suggest that the composite wall with 40 cm of hollow block filled with soil and 20 cm of hollow block filled with perlite had better thermal performance than the composite wall that was composed of with 40 cm hollow block filled with perlite and 20 cm filled with soil.