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The present research aims to achieve a shape-stable, and leakage-proof material for thermal energy storage (TES). The leakage analysis of 20 wt.% SiO2@Cu PCM shows 0.05%, as a result, more testing is conducted to assess its morphology, structure, and thermal properties. TGA and DSC studies demonstrated that the latent heat and thermal degradation rate (TDR) has been delayed, with a significant decrease in latent heat of roughly 8.7% compared to pure paraffin. Laser Flash Method (LFA) results revealed that the thermal conductivity (TC) of the PCM composite significantly increased 4.84 times than the paraffin. [ABSTRACT FROM AUTHOR]

Disodium phosphate dodecahydrate was hybrid with n-octadecane as the phase change material (PCM) by reversed-phase emulsification. The cellulose sponge obtained based on cellulose nanocrystals was used as the support material to fabricate a shape-stable composite phase change material (CPCM) through impregnation. It was laminated with cotton fabric to obtain a sandwich structure thermal insulation fabric. An infrared spectrometer, scanning electron microscope, differential thermal scanning calorimeter, and other equipment were used to characterize the morphology, chemical groups, and latent heat properties of CPCMs and thermal insulation fabrics. The results displayed that the cellulose sponge had a porosity of 99.03%, a density of 0.012 g/cm3, and could withstand 1900 times its weight. When the mass proportion of PCM in the composite system was 67.5%, its latent heat energy was 84.44 J/g, which also revealed optimal shape stability. Compared to the original fabric, the thermal insulation efficiency of the sandwich structured fabric was increased by 17.7%∼18.2%, and the photothermal conversion rate reached 25.88%, with good application performance. [ABSTRACT FROM AUTHOR]

The low ability of phase change material (PCM) to transfer thermal energy has created a serious challenge for the development of latent heat storage (LHTES) units. Embedding foam with high thermal conductivity material like copper has attracted significant attention. Besides, high porosity, lightweight, and easy usage are other important benefits of copper. However, its higher cost and decreasing effective volume of PCM led to the creation of amendments in the foam design. Employment of the foam in the form of fin or foam fin has emerged as an alternative method to benefit from the advantages of porous material and overcome its defects. In this study, various LHTES units with different numbers of foam fins have been simulated numerically and compared with pure PCM and fully foam PCM enclosures. Two practical boundary conditions including constant temperature and constant heat flux were examined for the designed systems. The obtained results demonstrated that foam fins have a remarkable effect on the thermal performance enhancement of LHTES under constant temperature boundary condition. For LHTES with six foam fins, 42% and 30% reductions in melting time were achieved for both types of boundary conditions including constant temperature and heat flux, respectively. At the beginning of charging process, a significant enhancement of input heat rate was proved for LHTES with 6 foam fins and fully foam up to 112% and 155%, respectively. In addition, the foam fins method provided some free volume of PCM to permit the falling out of natural convection of molten PCM. [ABSTRACT FROM AUTHOR]

This work presents the materials selection process, the design and the dimensioning process of a latent heat storage tank that works between a high temperature heat pump and an Organic Rankine Cycle unit. The selected heat storage material is the S117 Phase Change Material that has a melting point at 117°C matches the operational temperature of the system at approximately 120°C. The tank configuration is selected for optimised heat transfer process, resulted from practical experience of the project partners and it is described in details in the document. The simulation results from the Computational Fluid Dynamic study of the tank are also presented here. This work should be useful for engineers designing compact heat storage tanks for medium temperature applications. [ABSTRACT FROM AUTHOR]

Recently, solar thermal energy has been considered the main type of renewable energy used widely to provide heat energy and produce electrical power. Evacuated tube solar collectors (ETSCs) are used in various weather circumstances such as clear, cloudy, windy, hot, and cold weather, and their efficient system supplies latent heat storage fluid with higher temperature and lower heat energy loss compared to the flat-plate solar collectors (FPSCs). This review paper is considered an investigation on adding nanofluid particles to the evacuated tube solar collector-PCM, indicating future evacuated tube solar collector designs and predicting the suitable high- or low-temperature PCM for various types of applications. Also, three main types of ETSCs, heat pipe, Thermosyphon, and U-pipe, with their applications are reviewed, and the factors that influence the collector performance and efficiency are discussed. Moreover, the properties that affect the selection of the PCM and the usage of various types, sizes, and volumetric concentrations of nanofluid as a working fluid for each ETSC are investigated with their enhancements for each type. Lastly, this paper provides future ideas for using additive nanofluid materials as a working fluid to improve the performance and efficiency of ETSCs. [ABSTRACT FROM AUTHOR]

Strengthening the thermal response of Phase-Change Materials (PCMs) is an essential and active field of research with promising potential for advanced applications such as solar energy storage, building energy conservation, and thermal management in electronic devices. This article evaluates the efficacy of a new arc-shaped fin array in shell-and-tube heat storage systems to enhance the PCM response during the discharge mode. Different fin geometric parameters including the fin curvature angle, the fin spacing, and the nonuniform angle between fins in the top and bottom sections of the PCM domain were considered to identify the best-performing layout. The analysis shows that increasing the curvature of arc-shaped fins between 60° and 180° and increasing the fin spacing between 5 and 15 mm can significantly reduce solidifying time and improve heat recovery rates. Moreover, the arc-shaped fins are more efficient than conventional longitudinal (+-shaped) fins, which are commonly employed in thermal energy storage applications. Arc-shaped fins can also save discharge time by more than half and improve the rate of heat recovery by almost four times than that of+-shaped fins. The present findings suggest that arc-shaped fins represent a promising design for enhancing the heat-recovery aspects in PCM-based energy storage systems. [ABSTRACT FROM AUTHOR]

Thermo-hydraulic behavior of a Phase Change Material (PCM) plays a crucial role in deciding the performance of Latent Heat Storage (LHS) devices. Discharge or Solidification is the prime portion that determines the performance of the LHS device. This work numerically models solidification in a vertical tube-in-tube LHS device. The phase change is accounted for using the fixed grid enthalpy porosity method. An independent numerical model built is validated with the experimental model. Dimensionless parameters, namely Rayleigh Number, Stefan number, Reynolds Number, and L/D ratio, vary in the range of 9.19x105 to 39.45x105, 0.2 to 0.5, 600 to 3000, and 1 to 15, respectively. Among all parameters, the Stefan Number has the greatest impact on the solid fraction and solidification time. For estimating the Solidification Time and Solid Fraction, correlations are proposed. [ABSTRACT FROM AUTHOR]

In the study, the development of cotton and wool fabrics that exhibit reversible color change and heat regulation properties was aimed. For this purpose, poly(methyl methacrylate-co-glycidyl methacrylate)/thermochromic composite 1 (PMMA/GMA/TC1) and poly(methyl methacrylate-co-glycidyl methacrylate)/thermochromic composite 2 (PMMA/GMA/TC2) microcapsules which had both of color change and heat storage properties were applied to fabrics by bath exhaustion method. Differential Scanning Calorimetry (DSC) measurement results showed that all of the fabrics could store considerable latent heat energy, as the highest melting enthalpy was obtained for Cotton 1 and Wool 1 fabrics treated with PMMA/GMA/TC1 microcapsules. The Cotton 1 and Wool 1 fabric stored the latent heat of 76.1 J/g and 89.2 J/g, respectively. According to Thermal History measurement results, microcapsule applied fabrics exhibited cooling effect resulting from the released latent heat by 1-tetradecanol which was used as the solvent component of TCs. The visual photographs and color analysis results proved that the fabrics with thermochromic property showed reversible color change with temperature variations exceeding melting. [ABSTRACT FROM AUTHOR]

Thermal energy storage system has significant influence on energy conservation. Based on the literature review, it is identified that very few studies have been reported on performance assessment of latent and sensible thermal energy storage systems. This study presents an experimental study on latent and sensible thermal energy storage systems to investigate their performance during discharging cycle. Results have shown that the latent heat storage system has improvement of about 104% in discharging time and 4.1 times more energy is recovered as compared to the sensible heat storage system. It is recommended on the basis of obtained results to operate the systems at lower mass flow rate during discharging. [ABSTRACT FROM AUTHOR]

Industrial applications consume about one–third of global demand and account for nearly fifty percent of unutilized waste heat. Industrial waste heat recovery is a suitable solution. The tapping of waste heat from industrial activities has become inevitable energy conservation technology to reduce energy consumption and minimize the usage of fossil fuels to reduce carbon dioxide emissions. The conventional waste heat recovery installed on-site to meet local energy demand is a well-established technology. However, the topological mismatch between energy recovery and its demand remains a hurdle, especially for off-site heat demand located far away from sources. The Mobilized Thermal Energy Storage (MTES) alligates this issue. The economic and environmental study of MTES revealed that the standard energy cost (€/MWh) is proportional to transport distance. The energy cost (€/MWh) ranges from 40 to 80 with latent heat storage capacities latent heat storage capacity between 1.4 and 2.5 MWh and transport distance of 2 to 50 Km between source and end-users. The use of MTES reduces carbon emission up to 90% in comparison with conventional heating. Therefore, the transportation of waste utilizing thermal energy storage has become a trusted area of research. [ABSTRACT FROM AUTHOR]

Augmentation of the charging/discharging rate of the latent heat storage unit (LHSU) is one of the challenges in the design and development of the energy storage unit. Natural convection plays a pivotal role in this aspect which gets influenced by the inclination at which LHSU is placed. Employing radial fins enhance the heat transfer rate but there is a possibility of suppressing the natural convection. Providing perforations on the fins could assist the melted PCM to flow freely upwards and hence can overcome the issue of attenuation of natural convection. However, the orientation of LHSU may alter the influence of perforations. Hence in the current study, a comparative analysis on the thermal performance of a LHSU with solid and perforated fins at different orientations is presented. Experiments are carried out for both melting and solidification processes. It is observed that irrespective of the type of fin, orientation has a significant effect on the melting process. Regardless to the type of fin, total melting time is found to be 48% lesser in the vertical configuration in comparison with horizontal configuration. The considered design of perforations is found to be more effective in a vertical configuration as they increased the energy storage rate in the initial stages of melting. At other orientations, perforations do not have an ample effect. Fin effectiveness is observed to be 5% more in the case of solid fins in comparison with perforated fins at all the orientations. For the solidification process, orientation and perforations have negligible effect as the discharging process is conduction dominant. Exergy efficiency is noticed to be higher for vertically oriented LHSU in both the types fins during the charging process. During solidification of PCM, exergy efficiency is noticed to be same at all the orientations irrespective of the type of fin. [ABSTRACT FROM AUTHOR]

In this study, pure beeswax and its novel composite with expanded graphite (10% wt.) were tested for thermal storage efficiency in a rectangular shell and helical tube storage unit. Low thermal conductivity of beeswax is improved by adding expanded graphite of 10% wt. Thermal characterization of beeswax and its composite was performed using differential scanning calorimetry and thermogravimetric analysis. Effect of hot fluid flow rates (0.25 liter per minute [LPM], 0.5 LPM, and 1.0 LPM) and inlet temperatures (60ºC, 70ºC, and 80ºC) on the charging time of beeswax and its composite was studied and compared. Charging time of beeswax and its composite reduced with an increase in fluid flow rate and inlet temperature. At 0.5 LPM flow rate and 80°C inlet fluid temperature, the charging time of composite was reduced by 630 min as compared to pure beeswax. Smaller charging time, improved thermal conductivity, and better thermal storage efficiency of composite material suggest it as a useful storage material for a wider range of applications. [ABSTRACT FROM AUTHOR]

In this study, beeswax as a new energy storage material and its composite with expanded graphite were prepared and characterized for their surface and thermal properties. Surface characterization showed no chemical interaction between beeswax and expanded graphite. The thermal conductivity of the composite was improved with 117% enhancement. The thermal performance of beeswax and its composite as a heat storage material was studied in a rectangular shell-and-tube thermal storage unit. The melting point of the composite remained almost same as that of beeswax; however, the melting time was reduced considerably, from 540 to 360 min with inlet water at 80°C and a 2-lpm flow rate. [ABSTRACT FROM AUTHOR]

Thermal storage plays a vital role in improving the overall efficiency of a waste heat recovery system. A phase change storage system exhibits high energy storage density and isothermal behavior during the charging and discharging processes. In the present work, the cascading arrangement of the phase change storage system is studied to analyze the improvement in the efficiency of the storage system during the charging process, and to compared it with a single storage tank system. The performance parameters, such as the amount of heat recovered, the heat lost, charging rate, charging efficiency, and the percentage of energy saved, are investigated in detail. [ABSTRACT FROM PUBLISHER]

This study presents the analysis of phase change material (PCM)-based solar air heating system to achieve comfort conditions in a living space during winter season. The technical feasibility of PCM-based solar air heating system has been demonstrated, thus reducing the risks due to indoor air pollution caused by the use of fossil fuel or biomass combustion devices. The most sensitive parameters affecting the performance of storage unit are the melting point of storage material, mass of PCM, and airflow rate. The simulation results considering various flow rates and melting temperature of PCM indicate that, when melting temperature of PCM is equal to the comfort temperature of all the winter months, the storage unit performance is maximized for all the months during winter season. A new parameter, heating capacity of the PCM, has been introduced to illustrate the performance of the PCM storage. [ABSTRACT FROM AUTHOR]

A ventilated cooling ceiling with phase change material (PCM) was installed and measured in a 20 m2test room. The PCM used was DELTA®-COOL 24, a salt hydrate from the company Dörken with a melting range of 22–28°C. The PCM was encapsulated in polycarbonate containers which were laid on top of the bearing for the plaster boards. The amount of PCM installed was 9 kg/m2. The ceiling was rear ventilated to improve heat transfer between the PCM and the room air. During the cooling mode, the ventilation was purely in circulating operation with a volume flow rate of 97 m3/h (air exchange rate of 2/h). To regenerate the PCM, cooled air was inserted into the ceiling with a volume flow rate of 140 m3/h (air exchange rate of 3/h). Different positions for the containers were tested. The PCM in the ceiling delayed the rise in the room air temperature significantly. The PCM stayed active for 12–16 h, depending on the position of the containers. While the cooling power of the air flow alone was very small (30–40 W for the 20 m2test room), a significant amount of heat was transferred directly through the plaster boards of the ceiling. [ABSTRACT FROM AUTHOR]

In hot and dry climatic conditions of South Asia, summer night temperatures are low, and phase change material (PCM) based heat storage technique could be used as heat sink to reduce ambient air temperature during hot day times, as an alternate of current ventilation techniques for the building sector. This can help in reducing electricity consumption and consequently reducing green house gas emissions. This study presents the analysis of PCM storage unit using cooler night temperatures for charging of storage material and later acting as a heat sink for hot ambient air during day time in hot and dry climatic conditions. The influence of air flow rates and melting point of PCM on the availability of comfort temperatures at storage unit outlet has been studied. The results clearly indicate the feasibility of PCM storage unit as a heat sink to keep ambient air within comfort limits during the hot day time in summer season. When the PCM melting temperature is equal to the comfort temperature of the hottest summer month, the storage unit performance is maximized for all the months during the summer season. [ABSTRACT FROM AUTHOR]

A prototype of a solar chimney with a built-in latent heat storage system for prolonging ventilation system operation until evening/night or even 24 hours was designed and developed. Sodium Sulfate Decahydrate "Na2SO4.10H2O" (melting point 32°C, latent heat of fusion 126 kJ/kg) was used as a Phase Change Material (PCM) for latent heat storage. Experiments have been carried out with the air gap of 0.20 m and 45 degree inclination angle of solar chimney. Results showed that integration of PCM storage inside the solar chimney is positive and supplies a constant airflow rate of 155 m3/h in evening and night periods. Description of the fabricated prototype solar chimney with PCM storage, thermal analysis to predict the air flow rate, and temperatures of the component of the system with experimental results are presented. [ABSTRACT FROM AUTHOR]

With rising energy costs and an increasing demand for renewable energy sources, thermal energy storage (TES) systems are becoming an interesting option. TES is a key component of any successful thermal system and a good TES should allow minimum thermal energy losses. In this study, various ways of thermal conservation are outlined and discussed, both theoretical and experimental. In this respect, the TES systems and their practical applications and some selection criteria have also been given. [ABSTRACT FROM AUTHOR]