This study introduces a novel solution to the pressing challenges of higher energy consumption in the greenhouse: air-flowed containing particles circulated within a double-layer covering featuring spectral splitting (APSP).
Used as a greenhouse roof, this approach provides an effective method to achieve the reduction in the cooling and heating load of the greenhouse. The APSP system can split incoming sunlight into plant active spectrum (PAS: 300–800 nm) for crop growth and heat active spectrum (HAS: 800–1500 nm) for heating production. The APSP comprises a hollow structure formed by a highly light-transmissive outer film and a spectral splitting film (SSF) as the inner layer of the covering structure. Air-flowed containing spherical black particles made of polystyrene with low-density and high HAS absorption are circulated in the hollow structure driven by the fans. Through rigorous modeling and experimental testing, the study validates the system's optical and thermal performance. The Root Mean Square Error (RMSE) of optical performance and the relative error of photo-thermal performance between the model and the experimental data of the APSP are 2.7 % ∼ 5.4 %, and 4.8 %, respectively. The numerical simulation and experimental results show that the appropriate parameters of the APSP are: the average diameter of particles is 1.18 mm (D1.2) with the number per unit area (N) of 4.54 × 105, the velocity of the particles is 8 m/s with 20 mm fluid thickness. In this case, the average transmittance in PAS of the APSP is 20.9 % with the crop growth factor (G) of the APSP is 25.0 %, which is higher than the defined value of the G (24.8 %) to meet the growth of plants. The average absorption of the APSP in HAS is 92.1 %. The total solar energy utilization efficiency of the APSP is up to 57.2 %. Meanwhile, compared with the common greenhouse covered with a single film, the greenhouse with a covering of the APSP with particles filling rate of 95 % can decrease the heat transfer coefficient of 5.0 W•m−2•K−1 at night in winter. The APSP can reduce greenhouse cooling load by 32 % and heating load by 18 %, respectively.
In addition, the APSP system has a payback period of 1.03 years and the levelized cost of energy of 0.034 $/kWh within a 10-year life cycle. These results affirm the feasibility and benefits of the APSP as a roofing solution for energy-efficient greenhouses.
Yuan, Y., Wu, G., Yang, Q., Zhang, C., Wu, T., Wang, R., Qi, H., Nie, J., Wang, Y., Tan, D., Luo, Y., Li, B., Zhang, W., Liu, R., & Xie, Y. (2026). A novel spectral-splitting solar greenhouse roof with air-flowed containing particles between double covering: Experimental results and modeling. *Renewable Energy, 256*(Part G), Article 124498. https://doi.org/10.1016/j.renene.2025.124498
Source: Science Direct
