Solar thermal energy harvesting properties of spacer fabric composite used for transparent insulation materials

•We proposed and produced a novel flexible TIM model of spacer fabric composites.•The properties of TIMs in two different types of spacer fabric composite were measured and compared.•The coating process of poly-p-xylene was validated as an effective method to improve the thermal insulation property of TIMs.•Spacer fabric composites demonstrated to have large potential and extreme broad application prospect in the field of TIMs.

Transparent insulation materials (TIMs) hold an extraordinary potential in solar thermal energy collection, and are gradually and widely applied in the energy-saving buildings. However, due to the limitation of available materials, conventional TIMs are rigid, heavy and uneasy for installation. In this paper, a novel TIM product made of spacer fabric composites was designed and investigated experimentally. Compared with traditional TIMs, the proposed spacer fabric composites are featured with flexibility, low weight and high applicability. Four different types of spacer fabrics composites were developed to analyze the solar energy conversion efficiency using textile material. Their chemical composition, conductivity and water repellency properties were systemically evaluated using UV-VIS-NIR, thermal detector and contact angle measurements. The spacer fabric composites of spacer filament in 'X' type was demonstrated to have a stronger solar thermal collection capacity than that of 'V' type. Also, the poly-p-xylene coating contributed to a higher thermal insulation and stronger water repellency property. To be specific, the stable collection temperature of the optimal composites can reach to 98 °C from the ambient temperature of 32 °C at a radiation of 1100 W/m2. In conclusion, the spacer fabric composites demonstrated to have large potential and extremely broad application prospect in the field of transparent insulation materials.