Simulation and optimization of the thermal behavior of a Trombe wall under unsteady conditions

Abstract

This paper aims to analyze the heat transfer in an unvented Trombe wall. The wall exchanges by convection and radiation with two internal and external environments. During winter, it absorbs a variable solar flux through its outer surface, while during summer, it absorbs solar radiation via the glazing thanks to a thin black film. The conservation equations governing the problem were discretized by the control volume method and solved by the SIMPLE algorithm. The radiosity method was applied to evaluate the radiative fluxes exchanged by the lateral surfaces of the air layer. These numerical approaches were implemented in a numerical solver, which is validated against the findings of a similar study. Indeed, the differences recorded between the results do not exceed 7 %. In this work, the authors studied the thermal performance of the Trombe wall considering different building materials (fired clay, sand-lime, concrete, and fly ash) and different working fluids (air, helium, neon, argon, krypton, and xenon). The results are presented in terms of hourly variations of the incoming and outgoing fluxes and some metrics measuring the thermal performance of the studied system.