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Phase change materials (PCMs) are increasingly gaining prominence in thermal energy storage due to their impressive energy storage capacity per unit volume, especially in applications with low and medium temperatures. Nevertheless, PCMs have significant limitations regarding their ability to conduct and store heat, primarily due to their inadequate thermal conductivity. One potential solution for improving the thermal conductivity of PCMs involves the inclusion of nanoparticles into them. However, a recurring issue arises after several thermal cycles, as most nanoparticles have a tendency to clump together and settle at the container's base due to their low interfacial strength and poor compatibility. To address this challenge, including surfactants such as sodium dodecylbenzene sulfonate (SDBS) has emerged as a prevalent and economically viable approach, demonstrating a substantial impact on the dispersion of carbon nanoparticles within PCMs. The foremost objective is to investigate the improvement of thermal energy storage by utilizing graphene nanoplatelets (GNP), which are dispersed in A70 PCM at various weight percentages (0.1, 0.3, 0.5, 0.7, and 1.0), both with and without the use of surfactants. The findings indicate a remarkable enhancement in thermal conductivity when GNP with surfactants is added to the PCM, showing an impressive increase of 122.26% with a loading of 1.0 wt.% compared to conventional PCM. However, when 1.0 wt.% pure GNP was added, the thermal conductivity only increased by 48.83%. Additionally, the optical transmittance of the composite containing ASG-1.0 was significantly reduced by 84.95% compared to conventional PCM. Furthermore, this newly developed nanocomposite exhibits excellent stability, enduring 1000 thermal cycles and demonstrating superior thermal and chemical stability up to 257.51 °C. Due to its high thermal stability, the composite NePCM is an ideal candidate for preheating in industrial and photovoltaic thermal (PVT) applications, where it can effectively store thermal energy. [ABSTRACT FROM AUTHOR]

Solar energy is the most plentiful renewable energy source that has the capability to keep up with the growing demand. When the sun's energy is not available, thermal energy storage (TES) using phase change material (PCM) is a promising technique for storage and utilization. However, PCM's low thermal conductivity may limit its use. The use of nanomaterials to enhance the thermal conductivity is one of the prominent solutions to overcome this issue. This research work reports that graphene nanoparticles (0.1%, 0.3%, 0.5%, 0.7% and 1% mass) enhanced paraffin wax (PW) to improve the thermophysical properties and transmittance capability. Thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FTIR) and ultra-violet visible spectroscope (UV–VIS) were used for the characterization of the base PCM and nano-enhanced phase change materials (NePCM) composites. A significant improvement of 110% in thermal conductivity was obtained at 0.7% mass ratio compared to base PW without compromising the prepared composites' latent heat storage (LHS) capacity. TGA and FTIR outcomes demonstrated excellent thermal and chemical stability, respectively. To check the thermal reliability of composite, the PW and nanocomposite were subjected to repeated thermal cycling. The outcome evidence that the NePCM composite had consistent thermal energy storage properties even after repeated thermal cycles. The composite's light transmission was drastically lowered by 56.34% (PW/Gr-0.5) compared to base PW, resulting in PW/Gr composite has better thermal reliability in relation to thermal conductivity and LHS than base PCM, which can be used specifically in photovoltaic thermal systems and TES. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have received widespread thermal energy storage (TES) and release properties due to their unique characteristics. However, the PCMs suffer from poor thermal conductivity, resulting in the least thermal performance and heat transfer characteristics. This research focused on enhancing the heat transfer and storage characteristics by developing an organic paraffin wax composite by dispersing highly conductive graphene powder using a two-step technique. The results show that the developed nano enhanced PCM significantly improves the thermal conductivity by 72.2% at 0.6 wt% of graphene powder. Furthermore, the Fourier transform infrared spectrum shows there is no additional peak observed, means physically and chemically stable, and the reduced light transmission capability was enhanced by 32.0% than pure PCM. Due to its extreme characteristics, the developed PCM is an outstanding material for medium temperature solar thermal energy storage applications. • Thermal and chemical stability of graphene enhanced organic PCM has been analyzed. • The thermal conductivity of graphene enhanced PCM has significantly enhanced by 72.2%. • A remarkable reduction in light transmission of developed nanocomposite by 32.0%. • The Prepared nanocomposite PCM is suitable for medium thermal energy storage applications. [ABSTRACT FROM AUTHOR]

Concentrated Photovoltaic (CPV) system is one of the efficient and economical photovoltaics (PV) technologies. The fundamental principle of using CPV system is a substitution of expensive cell area with inexpensive optics. Concentrating the solar radiation on small areas enhances the power output. However, operating at high temperatures can potentially impair their life span and performance. Thus, cooling medium plays a crucial role in refining the CPV system's efficiency. The integration of the CPV system with Phase change materials (PCMs) provides a state-of-the-art hybrid design for both thermal and electrical outputs, suggesting a better utilization of solar energy. Nano-enhanced Phase Change Materials (NePCMs) were demonstrated to be the best combination for optimal behavior, such as storing and releasing energy quicker during the phase transition process without help from external systems. Key objective of this review article is to present the latest works and technical challenges on the application of PCMs and NePCMs in Concentrated Photovoltaic Thermal (CPVT) as cooling and thermal energy storage mediums to improve PV cell efficiency. This review leads to the current gaps in the research and recommends future work on developing new PCMs, and NePCMs integrated CPV systems for improved performance, life span and economic feasibility. [Display omitted] • Different active and passive cooling techniques of CPVT systems are presented. • Thermal regulation of PCM integrated with CPVT system are extensively analyzed. • Thermal regulation of NePCMs integrated CPVT systems are discussed. • Technical challenges associated with PCM integrated CPVT systems are discussed. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) system is one of the best options for harvesting, storing, and saving energy for long-term or short-term use of a modern energy production system. The nano-enhanced phase change materials (NePCM) are a new type of phase change materials (PCM) formed by suspended nano-sized particles in base PCM to improve the thermophysical properties of the base PCM. The major challenge in nanoparticle dispersion in PCM, especially for solar energy applications, is its poor thermal conductivity and light transmission capability. Present research aims to address the thermal conductivity and light transmission capability issues by dispersing pristine multi-walled carbon nanotube (MWCNT) and functionalized multi-walled carbon nanotube (FMWCNT) particles in various weight concentrations (0.1, 0.3, 0.7, and 1.0%) into the salt hydrate PCM. A two-step technique was implemented to develop the NePCM for various weight percentage of MWCNT and FMWCNT. The Fourier transform infrared (FTIR) spectrum shows the MWCNT and FMWCNT nano-sized particles physically mixed well in salt hydrate PCM and without disturbing the chemical properties. The thermal conductivity of developed composites at 0.7 wt% MWCNT/S50 (S50M-0.7) and 0.7 wt% FMWCNT/S50 (S50F-0.7) are 0.78 W/mK, and 0.92 W/mK, respectively. The Differential Scanning Calorimetry (DSC) results revealed that the maximum improvement in latent heat by 14.66% and 31.17% for 0.1 wt% MWCNT/S50 (S50M-0.1) and 0.3 wt% FMWCNT/S50 (S50F-0.3) respectively. Light transmittance of S50M-0.7 and S50F-0.7 reduced to 92% and 93.49% than pure salt hydrate PCM. It exhibits the reduction in transmittance, greater improvement in solar spectrum absorption, and excellent photothermal conversion. [Display omitted] • Study on Functionalized and non-Functionalized MWCNT enhanced PCM. • Comparative thermal performance of MWCNT and FMWCNT enhanced salt hydrate PCM. • A remarkable enhancement in thermal conductivity by 100% for S50F-0.7 • A substantial reduction in light transmittance by 93.49% for S50F-0.7 than base PCM. [ABSTRACT FROM AUTHOR]

Solar energy is an easily accessible and promising renewable energy source that could solve the current energy crisis. Thermal energy storage systems incorporating Phase Change Materials (PCMs) are widely preferred owing to their immense energy storage capacity. The thermal energy storage (TES) potential of PCMs has been deeply explored for a wide range of applications, but not limited to solar/electrothermal energy storage, waste heat recovery, energy savings in building, and thermal regulations. The inherent shortcomings like leakage during phase transition, poor thermal conductivity hamper their extensive usage. Nevertheless, it has been addressed by their shape stabilization with porous materials and dispersing highly conductive nanoparticles. This review article focuses on different synthesis methods for medium-temperature form stable composites and a special focus is given on their thermal performance. Following mathematical evaluators (enthalpy efficiency, crystallization factor, efficient energy per unit mass of PCM, and thermal conductivity enhancement/mass fraction of nanoparticles) are computed and used to evaluate the efficacy of Form stable Nano-enhanced PCMs (FSNePCMs). The variations in thermophysical properties along with the critical causes are condensed. The effects of porous support on the degree of supercooling, form stability & thermal cycling are briefed. Furthermore, the versatile potential applications of the form stable composites are detailed. Finally, the possible future directions associated with the development of FSNePCMs with high energy density are highlighted. This review delivers a systematic and in-depth insight into the progress of FSNePCMs considering synthesis routes, thermal performance, energy density, and thermal management. [Display omitted] • Summarised the various synthesis methods of FSNePCMs. • Analyzed the reasons for variation in thermophysical properties. • Post thermal cycling properties were considered. • Probable areas of practical applications were condensed. [ABSTRACT FROM AUTHOR]

Molten salts are utilized in concentrated solar power (CSP) as a working fluid to store and transfer solar thermal energy. In this study, we attempted to enhance the thermal energy storage (TES) characteristics of the ternary nitrate molten salt of KNO 3 , NaNO 2 , and NaNO 3 , also known as HITEC molten salt, using cupric oxide (CuO) as additives for CSP applications. HITEC was doped with 0.1, 1, 3, and 5 wt% of CuO nanoparticles using the two-step wet method. Differential scanning calorimeter (DSC) was utilized to evaluate the specific heat capacity, melting point, and latent heat of the prepared material. Thermal stability was measured by thermogravimetric analysis (TGA) while the characterization analysis was performed using Fourier-Transform Infrared (FT-IR) spectroscopy, Field Emission Scanning Electron Microscope (FESEM), and Energy Dispersive X-ray Spectroscopy (EDS). The results showed that 0.1 wt% CuO nanoparticles is the optimum CuO nanoparticles concentration which resulted in a specific heat capacity enhancement of 5.6%, a 30% improvement of latent heat, and 9% enhancement of thermal stability. The morphological analysis revealed the formation of bright chain-like nanostructure due to nanoparticle dispersion, which may the possible reason for the thermophysical property enhancement. • CuO doped Nano-enhanced HITEC molten salt has been studied and presented. • Specific heat capacity enhanced by 5.6% at 0.1 wt% of CuO nanoparticles. • Latent heat enhanced by 30% at 0.1 wt% of CuO nanoparticles. • Developed NEMS has potential to improve overall efficiency of CSP. [ABSTRACT FROM AUTHOR]

In recent years, photovoltaic thermal (PVT) systems have emerged as an imperative research area due to the escalating demand for energy worldwide. Phase change materials (PCMs) considered as the most suitable materials to harvest thermal energy effectively from renewable energy sources. As such, this paper reviews and explains the various aspects of PCM and Nano-Enhanced PCM (NEPCM) integrated PVT systems. The novel and recent developments in PVT research focusing on cooling and thermal energy storage with PCM and NEPCM and their applications in the heating ventilation and air-conditioning (HVAC), building integrated photovoltaic thermal systems (BIPVT), building integrated concentrated photovoltaic thermal systems (BICPVT) are critically summarized. In addition, this review also accentuates the different methods of preparing NEPCM and their thermo-physical properties at different operating temperatures for targeted applications. The present paper also highlights the use of nanofluid, PCM, and NEPCM in extracting the thermal energy from the commercially available for PVT system. In conclusion, this review recapitulates the effort taken by researchers around the world in enhancing the thermal performance system. It is also expected this review will provide greater insight to the new researchers in recognizing the fundamental science behind the development of thermal performance system and the mechanism to enhance further the overall performance of the PVT system. Image 1 • Preparation of nanocomposites and methods are discussed. • PCM and NEPCM integrated PVT systems are extensively reviewed. • Numerical simulation and prediction models are discussed and summarized. • Application of thermal energy storage in the PVT system is well organized. • Valuation of social, economic and technical feasibility of the PVT system are discussed. [ABSTRACT FROM AUTHOR]

Molten salts (MSs) are known for their advantages, such as being cheap, abundant in supply and can be operated at high temperatures. These advantages permit them for potential application as sensible storage media and heat transfer fluid (HTF) for concentrated solar power (CSP) plants. However, the thermal energy storage (TES) and corrosion properties of certain MSs are inadequate and in need of improvement. The present review focuses on how to improve these properties, i.e., mixing suitable nanomaterials (NPs) with different concentrations for improved performance. Based on the literature study, addition of a trivial amount of NPs into the base salts could increase their specific heat capacity (C p) and enhance the thermal conductivity (up to 300%) considerably. In addition, several other investigations have also reported a reduction in corrosion rate due to the addition of NPs into the base salt. However, the addition of NPs increases fluids viscosity. The increase in viscosity is undesirable, as it increases the pumping power and friction factor that directly influences the operating cost. Besides, the sedimentation of nanoparticles in the fluid is another issue that requires systematic investigation. Unlabelled Image • Recent advances in nano-enhanced molten salts for concentrated solar power plants • Specific heat capacity and thermal conductivity of nano-enhanced molten salts • Viscosity and corrosivity improvements by the use of nanoparticles • Enhancing concentrated solar power plant efficiency by nano-enhanced molten salts • Current prospects and challenges of using nanoparticles in molten salts [ABSTRACT FROM AUTHOR]