Developing of a novel fluid greenhouse shading system by computational fluid dynamics: Validation and hydraulic studies

One way of improving the thermal performance of greenhouses is using thermal insulators (thermal shading). In this study, the behavior of a novel dynamic shading system made of two-layer polycarbonate plates containing fluid was investigated by numerical method. In this system, according to the cooling and heating requirements also to control the incoming or outgoing radiation from the greenhouse, the appropriate fluid was pumped into the ducts between the polycarbonate plates by a hydraulic pump. Studying the hydraulic parameters, including intra-duct pressure and fluid velocity between plates, can be very useful for the proper design of the shading to minimize the energy required and run the system. The computational fluid dynamics (CFD) method and standard k-ε turbulence model simulated turbulent flow inside the shading ducts. Validation between experimental and numerical data showed an average difference of less than 5 percent between the experimental and numerical pressure drop data. The maximum velocity value of 0.96 ms-1 was obtained for the ducts inside. In comparison, the system pressure drops in single (series) and triple modes (parallel) it was 3793 Pa for the latter and 3439 Pa for the former, which indicates 9.3% decrease in pressure drop for the innovative and proposed design.