Explore the vast range of titles available.

Energy conservation in buildings has been the focus of many studies since nearly one-third of global energy consumption is due to buildings. Phase change material (PCM) technology promises to be an attractive solution for energy saving in buildings since it is a passive and effective technology, as demonstrated in the literature. Therefore, this study focuses on the energy-saving performance of PCM-integrated buildings located in a Mediterranean climate to reveal their energy-saving potential. PCM is integrated both in external or internal south walls and roofs of buildings under four different climatic conditions. EnergyPlus, which is a well-known building simulation software, is adopted for building thermal analyses. The effects of melting temperature, location of PCM layer in the wall, thickness of PCM layer, type of envelope (wall or roof), and PCM double-layer system in the wall are investigated. The corresponding energy savings and CO2 emission reductions are obtained for the considered cases. The results showed that up to 41.6% reduction in energy demand can be obtained depending on the PCM application. Besides, PCM with a low melting temperature (21 °C) favored heating energy savings, while PCM with a high melting temperature (29 °C) favored cooling energy savings. Moreover, the double-layer PCM system provided higher energy savings than the single-layer PCM system, especially in warm and arid regions (Sousse and Tozeur).

Phase Change Materials (PCMs) are materials that release or absorb sufficient latent heat at a constant temperature or a relatively narrow temperature range during their solid/liquid transformation to be used for heating or cooling purposes. Although the use of PCMs has increased significantly in recent years, their major applications are limited to Latent Heat Storage (LHS) applications, especially in solar energy systems and buildings. PCMs can be classified according to their composition, working temperature and application. Metallic PCMs appear to be the best alternative to salts and organic materials due to their high conductivity, high latent heat storage capacity and wide-ranging phase change temperature, i.e., melting temperature and chemical compatibility with their containers. This paper reviews the latest achievements in the field of low-melting point metallic PCMs (LMPM-PCMs), i.e., those with melting temperatures of less than 420 °C, based on Zn, Ga, Bi, In and Sn. Pure LMPM-PCMs, alloy LMPM-PCMs and Miscibility Gap Alloy (MGA) LMPM-PCMs are considered. Criteria for the selection of PCMs and their containers are evaluated. The physical properties and chemical stability of metallic PCMs, as well as their applications, are listed, and new application potentials are presented or suggested. In particular, the novel application of metallic PCMs in casting design is demonstrated and suggested.

This research presents a dual-pronged bibliometric and systematic review of the integration of phase change materials (PCM) in asphalt pavements to counteract the urban heat island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt research, highlighting a marked rise in the number of publications between 2019 and 2022. Notably, Chang’an University in China has emerged as a leading contributor. The systematic review addresses key questions like optimal PCM types for UHI effect mitigation, strategies for PCM leakage prevention in asphalt, and effects on mechanical properties. The findings identify polyethylene glycols (PEGs), especially PEG2000 and PEG4000, as prevailing PCM due to their wide phase-change temperature range and significant enthalpy during phase transitions. While including PCM can modify asphalt’s mechanical attributes, such mixtures typically stay within performance norms. This review emphasises the potential of PCM in urban heat management and the need for further research to achieve optimal thermal and mechanical balance.

Purpose This study aims to investigate the thermal performance enhancements of phase change materials (PCMs) through the integration of extended fins and CuO nanoparticles under the impact of solar irradiation. The research focuses on improving the melting behavior and thermal efficiency of PCM-based energy storage systems to facilitate the design of more efficient energy storage solutions. Design/methodology/approach The analysis is conducted on a top-heated rectangular thermal system filled with pure PCM and nanoparticle-enhanced PCM (NePCM) mixed with 0.01% Wt. CuO nanoparticles, with varying fin configurations considering PCM volume and surface area of fins constraint. The shape of the fin is modified from single to multiple numbers, maintaining the same surface area. The analysis is carried out both experimentally and numerically for the without fin case, and the study is extended numerically (utilizing the finite volume method) considering different sizes and positions of the fins. The study evaluates the impact of nanoparticle inclusion, fin geometry variations and the thermal performance of three different types of PCM (lauric acid, RT-35HC and P-58). Numerical results are validated against the in-house experimental results. Findings The study successfully validates the numerical simulations with experimental data, enhancing the credibility of the findings for real-world applications. The addition of 0.01% Wt. CuO nanoparticles to PCM resulted in a 16.36% enhancement in energy storage, as observed experimentally, whereas the numerical simulation showed an 8.55% increase. The inclusion of CuO nanoparticles accelerated the melting process across all fin configurations, with a notable enhancement parameter of 16.51% for the single fin arrangement. The introduction of a single fin structure increased the energy storage rate, but further additions of fins led to diminishing returns, with a maximum energy storage rate of 35.19 J/min achieved with CuO-enhanced PCM in the presence of single fin. The study also highlights RT-35HC as the most effective PCM, offering the highest energy storage and fastest melting speed, making it ideal for rapid thermal response applications. Research limitations/implications Future research could explore different types and concentrations of nanoparticles as well as a broader range of fin geometries and materials to further enhance the performance of PCM-based energy storage systems. Long-term experimental validation under real-world conditions would also enhance the applicability and reliability of the findings. Originality/value This study provides valuable insights into optimizing thermal energy storage systems by combining nanoparticle enhancement and fin geometry optimization. The results offer practical guidance for improving the efficiency and effectiveness of PCM-based energy storage units in various applications.

The present numerical study addresses the buoyancy assisted transient two-dimensional early-stage heat transfer and melting process of PCM’s in a square enclosure. Two PCM materials are used namely pure paraffin wax and paraffin with 1 mass % fraction of SiC nano particles. The square enclosure walls are subjected to a constant temperature of 65 °C (Hot wall) and 27 °C (Cold wall) at bottom and top side, respectively, while remaining sides of the enclosure are perfectly insulated. A finite volume (FVM)-based Ansys fluent software along with enthalpy-porosity method is used to capture the phase change process from solid to liquid. The pressure–velocity coupling is performed by coupled scheme, while pressure correction is done by PRESTO method. The transient variation of PCM liquid fraction, temperature, velocity and enthalpy are plotted. The results obtained shows that a notable difference is confined between early melting stages of both paraffin and nano-enhanced paraffin materials. The close observation of velocity vectors clearly shows that the addition of SiC nanoparticles in pure paraffin improves the convective heat transfer rate with time. The addition of SiC nano particles in paraffin reduces the melting time of paraffin but contrary influence the uniformity in temperature distribution and heat transfer characteristics. The presence of SiC nanoparticles increases the liquid fraction and temperature rise by 33% as compared with pure paraffin.

Solar PV panel cooling is essential to achieve maximum efficiency of PV modules. Phase-change material (PCM) is one of the prominent options to cool the panel and reduce the temperature, since PCMs have low thermal conductivity. Expanded graphite particles are used to enrich the structure and stability as well as to increase the thermal properties. In the present research work, polyethylene glycol (PEG) 1000 is used as a base material and expanded graphite for inclusive particle. A novel form-stable PEG1000/EG composite PCM mixture is prepared, using impregnation and dispersion method. Expanded graphite and PEG1000/EG sample phase compositions are investigated, using X-ray diffraction technique. No new peak is identified in the composite PCM sample. The surface morphology and structure of EG and PEG1000/EG are investigated, using scanning electron microscopy (SEM). Chemical stability analysis is done by Fourier-transform infrared spectroscopy. Thermal properties of the prepared composite PCMs are analysed by differential scanning calorimetry, thermogravimetric analysis (TGA) and KD2 pro analyser. Results show that addition of EG in various propositions (5%, 10% and 15%) enhances the thermal conductivity of PCM samples from 0.3654 to 1.7866 W mK−1, while melting point and latent heat of fusion of PCM samples are getting reduced. TGA thermographs are used to investigate the thermal stability of the composite PCM samples. TGA curves show that loss of mass happens above the operating temperature, and it is varied with different mass ratios of EG. Characterization of the prepared composite PCM samples is compared and found that PEG1000-85%/EG-15% is the best form-stable PCM, suitable for cooling the solar PV panel as well as to improve the electrical efficiency coupled with a decrease of temperature in the range of 35 °C to 40 °C.

In this work we derive temperature-dependent functions for the most important material properties needed for phase change studies with octadecane. Over 80 references are reviewed in which at least one thermophysical property of octadecane is measured. The functions are valid ±40 K around the melting temperature and are surrounded by their confidence interval. It turns out that the values for the solid phase have much broader confidence intervals than the ones of the liquid phase. Hence, more accurate measurements are particularly desirable for the solid state material properties.

Increasing the temperature of photovoltaic (PV) cells decreases their electricity generation. The use of phase change materials (PCMs) is one of the most common methods for controlling the rate of increasing the temperature of PV cells. This research focuses on thermodynamic analysis of PV/PCM systems with and without fins in maximum operating temperature of PV modules (85 °C). Polyethylene glycol 600 (PEG-600) and paraffin, with different melting points, have been studied experimentally as PCM in an indoor condition. Moreover, the effect of using fins was investigated. For this critical temperature, the results showed that using paraffin could be better for controlling the temperature of PV cells, due to its closer melting point with the module temperature. In the case of fins included, the temperature differences of 28.0 °C and 8.8 °C between the case of paraffin + fin and the case of PEG 600 + fin in comparison with the conventional PV module were measured, respectively. At this critical temperature condition, the output power of a PV module cannot exceed the half of its nominal power. The exergy efficiency of the paraffin + fin case was measured to 4.2% more than the conventional one. Also, entropy generation was calculated and reduction up to 5% was shown for paraffin + fin in comparison with the conventional one. Moreover, variations of the Rayleigh number for proposed cases are calculated too.

Purpose Phase change energy storage is an important solution for overcoming human energy crisis. This study aims to present an evaluation for the thermal performances of a phase change material (PCM) and a PCM–metal foam composite. Effects of pore size, pore density, thermal conductivity of solid structure and mushy region on the thermal storage process are examined. Design/methodology/approach In this paper, temperature, flow field and solid–liquid interface of a PCM with or without porous media were theoretically assessed. The influences of basic parameters on the melting process were analyzed. A PCM thermal storage device with a metal foam composite is designed and a thermodynamic analysis for it is conducted. The optimal PCM temperature and the optimal HTF temperature in the metal foam-enhanced thermal storage device are derived. Findings The results show that the solid–liquid interface of pure PCM is a line area and that of the mixture PCM is a mushy area. The natural convection in the melting liquid is intensive for a PCM without porous medium. The porous medium weakens the natural convection and makes the temperature field, flow field and solid–liquid interface distribution more homogeneous. The metal foam can greatly improve the heat storage rate of a PCM. Originality/value Thermal storage rate of a PCM is compared with that of a PCM–metal foam composite. A thermal analysis is performed on the multi-layered parallel-plate thermal storage device with a PCM embedded in a highly conductive porous medium, and an optimal melting temperature is obtained with the exergy optimization. The heat transfer enhancement with metal foams proved to be necessary for the thermal storage application.

Latent Heat Storage (LHS) with Phase-Change Materials (PCMs) represents a high energy density storage technology which could be applied in a variety of applications such as waste heat recovery and integration of renewable energy technologies in energy systems. To increase the sustainability of these storage solutions, PCMs have to be developed with particular regard to bio-origin and biodegradability. Triglycerides represent an interesting class of esters as the main constituents of animal and vegetable fats, with attractive thermal properties. In order to be used as PCMs, the thermal behaviour of triglycerides has to be fully understood, as in some cases they have been reported to show polymorphism and supercooling. This study assesses the suitability of triglycerides as PCMs by reviewing the literature published so far on their behaviour and properties. In particular, melting points, enthalpies of fusion, polymorphism, thermal conductivities, heat capacities and thermal cycling stabilities are considered, with a focus on LHS and thermal energy storage applications. In addition, the efforts conducted regarding modelling and the prediction of melting points and enthalpies based on chemical structures are summarized and assessed.