Improvement of the energy efficiency of a trombe wall using nano enhanced phase change material

Abstract

The Trombe wall is built using materials that have a higher thermal capacity to gather solar energy and materials that have a lengthy energy storage capacity. The researchers presented many designs for improving Trombe wall performance. One of several designs is to use phase change materials in Trombe wall design. To keep the heat gained from solar radiation and use it to heat the structure at night. A different design of a Trombe wall with phase change material is evaluated in this study. To boost the performance of the phase transition material, nano enhanced materials with high thermal conductivity were chosen to quicken the process of energy transfer. Organic PCM, which is recyclable, economically effective, chemically stable, and has a wide temperature range, was chosen as a phase change material. N-octadecane was employed as the phase change material, and n-octadecane with nano enhancement of Expanded Graphite was chosen for the NePCM. To improve the heat gain by solar radiation, pyrolytic graphite was chosen as Trombe wall material as it has high thermal conductivity. Finite Element Method simulations are performed on the Trombe wall model. Istanbul, Türkiye, weather data was collected. For the computations, average monthly solar radiation, daylight hours, ambient temperature, and wind speed were used. The initial room temperature was taken as 18°C. Simulations were run for the coldest 7 months, and room, NePCM, and Trombe wall temperatures were measured. The coldest months, December, January, and February, saw increases of 1.57°C, 1.23°C, and 1.40°C, respectively. Another simulation was performed with n-octadecane as the PCM without nano enhancement. This simulation focused on n-octadecane PCM with no nano-enhancement components. This simulation uses the same weather data, the Trombe wall design, room layout, and material properties to those utilized in the first NePCM simulation. A comparison of NePCM and PCM for the room, Trombe Wall, and PCM was carried out. While the differences between NePCM (nano-enhanced) and non-NePCM situations were minor in January, February, and December, March showed the most apparent discrepancy. This pattern can be traced to the interaction of two factors: Despite having less sunshine than April, March had a greater level of solar radiation. This increased solar input to the Trombe wall's thermal gain exacerbated the temperature disparity seen with NePCM. The latent heat storage capability of NePCM most certainly played an important influence in March. During periods of intense solar radiation, the PCM absorbed and stored thermal energy, gradually releasing it during cooler parts of the day or on subsequent days when solar input was limited. This latent heat buffer allowed for a more sustained temperature increase than in circumstances lacking NePCM. For the seven months, the average energy gain of the NePCM was 16% higher than the PCM. This development can be attributed to improved thermal conductivity and heat transfer potential, facilitated by the nano-designed structure of the NePCM, which allows for more efficient absorption and retention of thermal energy within the material. It was determined that nano enhanced phase change material is more efficient than non-nano enhanced phase change material.