Papers by Keyword: Phase Change Material (PCM)

Abstract: In this study, a comparative thermal performance analysis was conducted on three roof configurations under the hot climate of Iraq/Basra to evaluate their potential contribution to Nearly Zero Energy Building (nZEB) objectives. The first two models incorporated Phase Change Materials (PCM) with different melting points (24°C and 29°C) arranged in varying sequences, while the third model represented a traditional roof with EPS insulation and concrete. Annual simulations using Design Builder program assessed the impact of PCM layer arrangements on indoor thermal regulation and cooling energy demand reduction. Results demonstrated that the PCM-based roofs significantly reduced indoor temperature fluctuations compared to the traditional roof, directly translating to substantial reductions in cooling energy requirements a critical factor for nZEB feasibility in hot regions. The configuration with PCM29 on top followed by PCM24 proved most effective, consistently maintaining indoor temperatures within a narrower and more comfortable range with daily averages 32.7°C, thereby minimizing the need for active cooling. In stark contrast, the traditional roof exhibited higher variability with peaks exceeding 42°C, indicating significantly greater cooling loads. These findings highlight that strategic optimization of PCM layer arrangement in roofs is a highly effective passive cooling strategy. This approach not only enhances occupant comfort but also dramatically reduces building cooling energy consumption, representing a vital step towards achieving nearly zero energy building performance in energy-intensive arid climates.

Abstract: Phase Change Materials (PCMs) have become popular for thermal energy storage (TES) uses due to their large latent heat capacity and almost isothermal performance. However, melting rates and the overall effectiveness of the system are constrained by their intrinsically poor heat conductivity. Considering latest studies investigating innovative shapes and combinations to optimize heat transfer achievement, fin insertion has become an effective and affordable upgrade technique. The most recent computational and experimental studies on fin-enhanced latent heat thermal energy storage (LHTES) systems are covered in this review, with a concentrate on how fin materials, forms, and configurations enhance PCM melting performance. Fin shapes such as longitudinal, radial, tree-like, spiral, T-shaped, V-shaped, fractal, and hybrid fins have been studied with respect to temperature uniformity, natural convection impacts, and melting time decrease. The outcomes demonstrate that improving fin shape could decrease melting times by as much as 70%, with geometric and tree-like fins performing better due to increased conduction–convection coupling. Furthermore, included in the research are design trade-offs involving fin volume against surface area as well as the impact of computational optimization in the design of fin shape. subsequently, research gaps and future initiatives are noted, with a focus on the possibility of hybrid improvement techniques that combine heat transfer fluid optimization or high-conductivity additives with advanced fin design.

Abstract: A new form of composite PCMs is developed by adding 0.5 wt% of SiO₂, TiO₂, ZnO and CuO nanomaterials to lauric acid. Phase change temperatures of lauric acid range from 43.92°C to 44.65°C and 40.84°C to 41.36°C, respectively. In addition, the phase change latent heats are 183.23 kJ/kg and 183.68 kJ/kg at room temperature, respectively. Thermal properties of PCM with nanomaterials were discussed in terms of weight fractions. The improvement in thermal conductivity of the PCM owing to the dispersion of nanomaterials was verified by laser flash analyser (LFA). Hence, the newly developed composite PCMs holds great potential as a candidate for harnessing solar energy in low-temperature heating systems. Keywords: Phase Change Material (PCM), Melting, freezing, Nanomaterials and Lauric acid.

Abstract: Thermal energy storage (TES) based on hidden heat concept is good substitute for sensible heat storage because of its dense storage capacity and almost constant temperature heat transfers during the charging and discharging cycle. During no load and low cooling load conditions the system stores the thermal energy in the storage medium (phase change material) which will be used latter to meet the requirement in off cycle conditions. The intention of present work is to increase the system off cycle time, maintain required temperatures during power cuts by joining a few inch thick layer of phase change material on the outer surface of the evaporator. For investigation purpose a deep freezer which runs on vapor compression system of 50 liters storage capacity is fabricated with and without phase change materials. The eutectic compositions nearly 23 wt% salt (NaCl) dissolved in water and aluminium nitrate around 26 wt% dissolved in water are used as phase change materials. By the end of all experimental investigations it was noticed that the off cycle time system with phase change material is increased by 5.5 hours compared to system without phase change material, food storage time is enhanced by 8 to 14 hrs and a little power saving also achieved.

Abstract: In the study work effect of PCM on the triangular pyramid solar still was experimentally investigated for the climatic condition of Chennai. Experimental studies were conducted and the use of PCM on storage was compared with a solar still without PCM and the PCM used is paraffin wax. The latent heat energy storage is increased with the use of paraffin wax while the energy stored is utilized during the absence of solar radiation by rejecting its heat through the basin to water for further evaporation. The temperatures of various elements of the solar still were measured using a thermocouple. Results show that there is an increase in productivity of 20% when compared to the solar still without PCM.

Abstract: The purpose of thermal energy storage systems (TES) is to store the heat energy supplied to it for a considerable time period and give the energy back when ever need arise. On many of occasions, part of the heat energy of various systems is unutilized. If this excess heat energy be stored in such systems as TESS, utilization of energy improves. If the use of such systems is widespread, fuel is conserved and national economy is saved.Different materials can be used in TESS to store heat energy and in the present work two such materials, which are popular phase change materials (PCM) namely (a) Paraffin (b) Stearic acid are used and subsequently the performance of the TESS is studied. The PCMs are used in the form of spherical capsules made up of high density poly ethylene (HDPE) of diameter 58 mm. Charging time and amount of heat energy recovered are studied for the two PCMs mentioned above and compared. Though paraffin as PCM gives little better heat energy recovery, performance of both the materials are almost the same. Hence as the cost of stearic acid is less when compared to paraffin on economical grounds and on ease of availability basis stearic acid has advantages over paraffin.