Development and Tests of the Solar Air Heater with Thermal Energy Storage

Abstract

Passive solutions in buildings have recently been rediscovered because they allow the rational use of solar radiation, which promotes energy savings. Thermal energy gained from the sun may be stored in the form of sensible heat in accumulative solid materials in a building envelope. This paper proposes an innovative solar air heater that captures and accumulates solar energy during the day and releases it during the night. The analyzed system is based on inexpensive ceramic modules, which can be used to construct thermal storage walls or solar chimneys in modern buildings. Both configurations have been tested experimentally and by a numerical model in ArCADia BIM software. Experiments have been carried out in laboratory conditions using a specially developed prototype. Among other parameters, power transferred from the solar air heater to the ventilation air in different conditions has been analyzed. When airflow was set to 150 m3/h, the maximum power observed under stable working conditions was approx. 355.0 W when the developed solar air heater operated as the solar chimney, and approx. 165.0 W when it operated as the solar thermal wall. When airflow was set to 200 m3/h, the maximum power was approx. 385.0 W. Experimental results have been used to calculate the efficiency of the solar air heater in real conditions. The total efficiency in the case of the solar chimney was estimated as 0.25, while in the case of the thermal wall it was estimated as 0.78, which resulted in an annual reduction in energy usage at a level of 190.7 kWh and 556.1 kWh, respectively (4.8 and 14.0%). In practice, these values can be significantly higher due to the possibility of increasing the length and shape of the accumulation heat exchanger.

Investigating the impact of Trombe wall parameters on thermal performance and room temperature in the Iraqi climate

“…The governing equations for unsteady fluid flow and heat transfer, as represented by Equations ( 1) through (6), and the associated boundary condition equations are solved numerically using the finite volume method. To address and mitigate unrealistic pressure oscillations, a staggered grid approach is employed for computing the velocity components, while scalar variables are calculated on the main grid.…”

“…These systems have the potential to yield yearly energy savings ranging from 30% to 70%, depending on design factors such as wall size, orientation, insulation, glazing, and prevailing climatic conditions. 5,6 Among various types of passive solar systems, the Trombe wall holds special significance due to its widespread use as a passive solar technology, appreciated for its simplicity, low or no maintenance requirements, and zero operating expenses. A Trombe wall consists of solid, darkcolored masonry with a glass panel positioned in the front.…”

“…Therefore, it is essential to assess how a Trombe wall functions in particular climatic conditions and how it may perform best. A comprehensive examination of existing research encompassing review papers, 5,6,[24][25][26][27] has revealed a significant lack of full-scale field investigations of Trombe walls designed to match the Iraqi climate. In light of this research gap, this paper presents a numerical and experimental study of Trombe wall performance and impact of its parameters on energy savings and temperature variation within a full-scale test room located in Iraq.…”

“…Solutions such as solar roofs, solar chimneys, and Trombe walls have all demonstrated significant improvements in energy efficiency. These systems have the potential to yield yearly energy savings ranging from 30% to 70%, depending on design factors such as wall size, orientation, insulation, glazing, and prevailing climatic conditions 5,6 …”

Nearly zero energy building design and optimization: A residential building transformation in Türkiye

“…To improve the energy efficiency of buildings, many countries are promoting the use of renewable energy (Sornek et al, 2023). Efficient buildings are needed to contribute to sustainable development.…”