A Simulation of Non-Ventilated Trombe Wall Performance With Graphite-Enhanced Phase Change Material

Abstract

This research evaluates the performance of a non-ventilated Trombe wall in three contrasting climates in Iran including Lavasan (cold-mountainous), Yazd (hot-dry), and Tabriz (cold-semi-dry). Simulations were conducted using DesignBuilder/EnergyPlus. The sample building was a residential space, and the studied non-ventilated Trombe wall consists of double-glazed low-emissivity glass, an air cavity, a dark concrete wall, and side polyurethane insulation. To enhance heat storage, graphite-enhanced phase change materials (PCM) was used. The baseline energy model was validated using monthly utility bills, achieving ASHRAE-compliant accuracy (CV(RMSE) < 5%). The evaluation indices included thermal loads, total annual energy, and CO₂ emissions. The non-ventilated Trombe wall mainly reduced heating demand, while its impact on cooling loads was limited. Total energy savings were recorded as 13.3% in Lavasan, 9.6% in Yazd, and 8.1% in Tabriz. The integration of PCM, however, significantly improved these savings, increasing them to 20% in Lavasan, 18.2% in Yazd, and 13.8% in Tabriz, respectively. For the PCM integrated Trombe wall, the reduction in annual CO₂ emissions was 11.4% in Lavasan, 10.6% in Yazd, and 2.7% in Tabriz. -An analysis of sensitivity regarding the thickness and placement of PCM, along with an assessment of the PCM liquid fraction, suggests that the performance of the system is determined by the degree and duration of phase change activation. Furthermore, the placement of PCM within the wall assembly is equally as significant as the thickness of the PCM. In summary, this study demonstrates that integrating graphite-enhanced PCM with a non-ventilated Trombe wall enhances thermal stability and energy efficiency across all climates, providing the most significant benefits in cold-mountainous climates followed by hot-dry climates.