Low-temperature macro-encapsulated phase change material based thermal energy storage system without air void space design

Development of low-temperature eutectic phase change material with expanded graphite for vaccine cold chain logistics

Development, characterization and modification of mannitol-water based nanocomposite phase change materials for cold storage

The effect of low temperature phase change material of hydrated salt on the performance of magnesium phosphate cement

Coupling thermal energy storage systems to heat pumps is an effective way to manage the utilization of thermal energy with respect to its demand. In this work, a thermal energy storage (TES) unit consisting of water and phase change material (PCM) was investigated experimentally by a laboratory scale test rig where lauric acid was used as PCM. The experiments were conducted for the cases including only water inside the TES unit and for those involving water and PCM inside the TES unit, separately. Using the data obtained from the experiments as well as by the knowledge of the system operation, a numerical model was established via grey-box modeling approach. Developed model allowed to investigate an impact of various PCMs and different effective thermal conductivity values of PCMs on the heating times, as well as the load shifting potential, in consideration of four different heating loads. The experimental results showed that incorporation of lauric acid into the TES unit resulted in lower heating times by 16% during thermal discharge; however, its inclusion improved the coefficient of performance significantly. Furthermore, the load shifting index was also improved by 10% using PCM, instead of using water only. Numerical outcomes revealed that using PCMs with high latent heat capacity and with a phase change temperature around the mean of the lowest and highest water storage temperatures could help achieving longer heating time (~4%) during discharge. Besides, load shifting could be enhanced using the aforementioned PCM (RT44HC). Consequently, it was deduced that the low thermal conductivity of PCMs is significant challenge for thermal energy storage. The heat transfer enhancement implementations are strongly recommended to achieve further improvement in the aforementioned performance parameters.

Liquid propellant engines: N. I. Melek-Pashayev. Translated from the Russian by W. E. JONES; edited by B. P. MULLINS. Oxford: Pergamon Press, 1962. 175 pp. (illus.). 20 s

Low-temperature phase-change materials (PCMS) were mixed with water to enhance the performance of heat transfer fluid. Several PCMs were tested in a laboratory-scale test loop to check their suitability to district cooling applications. The phase-change temperatures and latent heats of fusion of tetradecane, pentadecane, and hexadecane paraffin waxes were measured using a differential scanning calorimeter. The heat of fusion of these materials is approximately 60% of that of ice. They exhibit no supercooling and are stable under repeated thermal cycling. For 10% and 25% PCM-water slurries, the heat transfer enhancement was found to be approximately 18 and 30 percent over the value of water, respectively. It was also found that, in the turbulent region, there is only a minor pumping penalty from the addition of up to 25% PCM to the water. It was demonstrated that pentadecane does not clog in a glass-tube chiller, and continuous pumping below its freezing, point (9.9[degrees]C):was successfully carried out in a bench-scale flow loop. Adding PCM to water increases the thermal capacity of the heat transfer fluid and therefore decreases the volume that needs to be pumped in a district cooling system. It also increases the heat transfer rate, resulting in smaller heat exchangers. Research is continuing on these fluids in order to determine their behavior in large-size loops and to arrive at optimum formulations.

Stabilizing a low temperature phase change material based on Glaubers salt

Numerical analysis and optimization of the heat transfer enhancement from the heat transfer fluid side in a shell-and-tube latent heat thermal energy storage unit: Application to buildings thermal comfort improvement

With the intensification of global warming and the explosive growth of cold chain logistics demand, the energy consumption and carbon emissions of refrigeration systems are becoming increasingly prominent. Phase change materials (PCMs) show broad application prospects in cold chain transportation, building energy conservation, electronic cooling and smart textiles due to their high latent heat energy storage density and temperature control capabilities. however, conventional phase change materials suffer from problems such as supercooling, phase separation, leakage and poor thermal conductivity, which limit their practical application. Microcapsule encapsulation technology effectively solves the above problems by constructing a core-shell structure, significantly improving the stability and thermal response efficiency of the material. This paper systematically reviews the classification, properties and current status of low-temperature phase change materials in different fields, focusing on the preparation methods, wall material selection, modification strategies and research progress of phase change microcapsules in improving thermal conductivity and suppressing supercooling. Studies have shown that the comprehensive performance of phase-change microcapsules can be significantly improved through the modification of shell and core materials, providing theoretical basis and technical support for their large-scale application in high-efficiency energy storage and temperature control systems. Future research should further focus on the development of multifunctional composite microcapsules, the optimization of large-scale manufacturing processes, and the feasibility and economic analysis of their integration into renewable energy storage and intelligent thermal management systems.

One of the most applicable geometries for a thermal energy storage unit is an annulus filled by phase change material (PCM). In time-sensitive applications, the charging and discharging rates of PCM are critical. In the early stage of the period, the phase change rate is high, and it becomes so low by progressing the time, especially in the pure conduction zone at the later stage. Staggering the tube increases the charging or discharging rates and decreases another. The enhancement of both the charging and discharging rates is desirable. To achieve this in the present study, to improve the heat transfer and phase change rates, the application of the magnetic field of an electric current-carrying wire at the top or the bottom of the annulus in order to induce a convection heat transfer in the nanoparticles-enhanced PCM (NePCM) is presented. The solution is validated with experimental and numerical data. The predicted result indicates that employing the wire at the top of the annulus can reduce the solidification time by 25%. The application of the magnetic field is more efficient in the charging process where the wire is employed under the annulus, which intensifies the melting rate up to 40%. Accordingly, considering the appropriate locations of the wire, a conceptual design of thermal energy storage unit under the magnetic field efficient in both charging and discharging processes is developed.

Numerical and experimental investigation on a latent heat thermal storage device featuring flat micro heat pipe arrays with offset strip fins

An experimental and numerical study on phase change material melting rate enhancement for a horizontal semi-circular shell and tube thermal energy storage system

Effective thermal energy storage is essential to overcome the intermittent availability of solar energy. A small cylindrical thermal energy storage unit is investigated to provide heat during the early morning for domestic hot water using flat plate solar water heaters. A helically coiled heat transfer tube (HTF) in cylindrical thermal storage is investigated on charging phase-change material (PCM). An acrylic cylindrical container is used to hold the PCM. HTF tube is made up of copper helical coil with and without a conical section at the bottom of the loop. The heat transfer tube at the bottom is formed into a small conical shape at the helical coil’s center. The selected PCM is paraffin wax with a melting temperature of about 60°C. The HTF temperature is maintained at 75°C at a flow rate of 0.5 kg/min to charge the PCM of 1 kg mass. Part of solid PCM at the container’s bottom was observed with a longer duration to melt entirely without a conical section of the HTF tube. The irregular temperature distribution was also observed in PCM, mainly along the vertical direction. Thus, the complete melting was achieved by a conical coiled heat transfer tube at the container’s bottom. The conical coil length of the HTF tube increased the overall length by 10%. The PCMs melting duration with a conical tube at the bottom reduced significantly by 16% and enhanced average storage effectiveness by 13.06% compared to the HTF tube without the conical coil. Abbrevations: HTF: Heat transfer fluid; LHS: Latent heat storage; PCM: Phase-change material; TES: Thermal energy storage

Numerical simulation of effective thermal conductivity and pore-scale melting process of PCMs in foam metals

Coupled conjugate heat transfer model for melting of PCM in cylindrical capsules