Performance simulation of an unglazed transpired solar collector: two-dimensional and three-dimensional analysis

Abstract

The increasing depletion of fossil fuel resources and their rising costs highlight the need for alternative renewable energy technologies, such as unglazed transpired solar collectors (UTSCs). These systems utilize solar energy to preheat outdoor air, enhancing energy efficiency and reducing dependence on conventional heating. This study presents a numerical analysis of UTSC performance under Lithuanian climatic conditions using two- and three-dimensional models developed in ANSYS FLUENT. The 3D model simulates a wall fragment composed of two horizontally repeating sheet metal profile sections and ten vertically repeating sections, maintaining a realistic air gap. The 2D model, with a geometry of 375 × 16,600 mm, represents a longitudinal section applicable to any UTSC. The analysis evaluates the velocity of air flow, pressure distribution, and the increase in air temperature. The overall efficiency was found to be 54.32% for the 3D model and 54.07% for the 2D model. Both models were validated against the measured data. The study highlights the strengths and limitations of each modelling approach. The development of such models would allow for a faster and more reliable assessment of the application of UTSC in specific applications in industrial and other buildings.