Performance study on a novel greenhouse cover structure with beam split and heat control function

Abstract

Based on the principle of spacing prism, a novel greenhouse cover plate with beam split and heat control function is proposed. The visible light needed for plant growth transmits into the greenhouse and near-infrared radiation is absorbed to reduce the internal temperature. The target is to design a greenhouse cover plate that can not only reduces the temperature of greenhouse, but also reduces the energy consumption of greenhouses cooling system in summer. The relative position and size of the heat-absorbing plate are obtained through theoretical calculations. Based on the Monte Carlo light tracking principle, optical software is used to optimize the operating mode of the heat-absorbing plate. The relationship between air flow, efficiency and outlet temperature are analyzed by CFD numerical simulations. The integrating box is designed on principle of integrating ball, which is used to test this device's transmission and thermal characteristics. The test results are compared with double-layer vacuum glass under actual weather conditions. The results show that the transmission rate of spectral temperature control cover structure (STCCS) is about 60 % in the morning and afternoon, but it is lower at noon, approximately 47.32 %. Based on the thermal characteristic experiment results, it can be known that the average inside temperature of the STCCS box is decreased by 3.16 °C compared with the double-layer vacuum glass, and the thermal load is reduced by 21 %.