Dynamic simulation model for the design and optimization of a novel high-vacuum solar thermal collector

This paper focuses on the design of an innovative high-vacuum solar thermal collector, for which a novel dynamic simulation model is developed. As it is well known, standard flat plate solar thermal collectors are affected by thermal losses which significantly reduce their energy performance. Among all thermal losses, convective and radiative account for approximately 80% of the overall. To reduce these losses, a novel innovative flat plate solar thermal collector characterized by a high-vacuum space (i.e. 10-8 mbar) between the glass cover and edge is developed. The vacuum space is made with the aim of insulating the absorber serpentine with a consequent convective thermal loss reduction. In addition, the serpentine absorber system is suitably painted with a solar coating for reducing the radiative thermal loss. Thus, the presented prototype allows store hot water with no need for any additional storage system. In this paper, a mathematical model able to assess the energy performance of the innovative high-vacuum prototype is also presented. The tool is based on a detailed 3D transient finite-difference thermal network and it is validated against the experimental data obtained by different experimental tests.