Phase-change materials (PCMs) offer an effective way to store and release thermal energy to balance the supply and demand for energy. Both the melting and solidification processes have a major impact on how effectively energy storage works and also it is affected by the thermal conditions of the heating or cooling source. Thermal energy storage systems using (PCMs are often limited by slow melting and solidification rates. The current work explores a novel strategy of cyclic heating and cooling for improving the PCM melting and solidification process combined with variations in fin shapes and orientations, to address these inefficiencies. The fins are heated and cooled following cyclic heating and cooling pattern for three different cycle periods (CP) with same amplitude. As a result, PCM is subjected to cyclic heating and cooling. The finite volume method is employed to analyze the impact of cyclic heating-cooling cycles on PCM performance. An analysis is also conducted on the impact of the relative shape of fins-that is, flat, concave, and convex, positions-vertical and horizontal-on the melting and solidification process under three different cycle periods. By applying a finite volume-based computational approach, the numerical model is solved. It is observed that the overall thermal performance of PCM-based energy storage is modulated by the cyclic heating-cooling arrangements. With this, melting time is reduced by 47.1 % compared to horizontal fin arrangement. When the fin pair is arranged vertically (theta = 0 degrees), with the increase in the cycle period to CP3, the amount of stored energy (during the heating cycle) is about 24.7 %. Similarly, the amount of stored energy recovery (during the cooling cycle) is about 43.6 %. When the fin pair is arranged horizontally (theta = 90 degrees), the amount of energy stored is up to 10 % due to the increase in the cycle periods. Similarly, the amount of stored energy recovery (during the cooling cycle) is about 38.5 %. An improved fin designs, combined with cyclic heating-cooling strategies, present an effective solution to enhance PCM-based thermal energy storage systems.

Phase-change materials (PCMs) are recognized for their effective role in thermal energy storage systems, offering the potential to balance fluctuations between energy supply and demand by absorbing, storing, and releasing heat during phase transitions. The performance of such systems, however, is heavily influenced by the melting and solidification behaviors of the PCM, which depend on the system’s geometric configuration and heat source placement. In this research, a comprehensive numerical analysis is conducted to examine the thermal behavior of a PCM-filled energy storage unit, with particular focus on the effects of heater and cooler positioning (bottom, side, and top) and the influence of two distinct geometrical shapes (square and circular). A finite volume-based computational technique is employed to solve the governing equations, and the numerical outcomes are validated against experimental data from in-house tests. The investigation covers both the melting and solidification stages for two geometries under different Grashof numbers (Gr), which quantify the strength of natural convection within the system. The results reveal that heating from the side offers the quickest melting performance, especially for the circular configuration at lower Gr values, where a melting rate 240% higher than bottom heating is observed. On the other hand, top heating proves to be the least efficient. For solidification, the best performance is obtained using a square geometry with a top cooling configuration, resulting in a solidification rate 15.4% faster than the bottom cooling scenario. This study highlights the critical role of geometric shape and heater/cooler positioning in enhancing the thermal response of PCM systems. The findings suggest that side heating combined with circular geometries is optimal for accelerating the melting process, while square geometries with top cooling enhance the solidification rate. Future research areas include exploring more complex geometries, varied boundary conditions, and different PCM materials with distinct thermal characteristics.

The orientation of the container filled with phase change material (PCM) is a critical parameter that significantly effects the performance of thermal energy storage systems. In this study, the Computational Fluid Dynamics (CFD) method is utilised to analyse the effects of container position on the melting process of PCM. Unlike conventional methods, the melting process of PCM was conducted using the hot air jet impingement method. The study investigated the impact of two various Reynolds numbers (2235 and 4470) and three different H/D ratio (the ratio of the distance between the jet and the container to the container diameter) which were 0.4, 0.5, and 0.6, on the PCM melting process. In addition, regression analysis was executed using the Extreme Gradient Boosting algorithm (XGBoost). The outcomes unveiled that the artificial intelligence model attained a minimum accuracy of 97.89 % and reached a maximum accuracy of 99.35 % across the 12 datasets for comparing performance metrics. These results serve as a testament to the prowess of the XGBoost algorithm in providing precise predictions of the target variable within a notably extensive range of accuracy for the datasets under consideration.

Purpose The purpose of this study is to examine the effects of inclination angle on the thermal energy storage capability of a phase change material (PCM) within a disc-shaped container. Different container materials are also tested such as plexiglass and aluminium. This study aims to assess the energy storage capacity, melting behaviour and temperature distributions of PCM with a specific melting range (22°C–26°C) for various governing parameters such as inclination angles, aspect ratios (AR) and temperature differences (ΔT) and compare the melting behaviour and energy storage performance of PCM in aluminium containers to those in plexiglass containers. Design/methodology/approach A finite volume approach was adopted to evaluate the thermal energy storage capability of PCMs. Five inclination angles ranging from 0° to 180° were considered and the energy storage capacity. Also, the melting behaviour of the PCM and temperature distributions of the container with different materials were tested. Two different AR and ΔT values were chosen as parameters to analyse for their effects on the melting performance of the PCM. Conjugate heat transfer problem is solved to see the effects of conduction mode of heat transfer. Findings The results of the study indicate that as AR decreases, the effect of the inclination angles on the energy storage capacity of the PCM decreases. For lower ΔT, the difference between the maximum and minimum stored energies was 20.88% for AR = 0.20, whereas it was 6.85% for AR = 0.15. Furthermore, under the same conditions, the PCM stored 8.02% more energy in plexiglass containers than in aluminium containers. Originality/value This study contributes to the understanding of the influence of inclination angle, container material, AR and ΔT on the thermal energy storage capabilities of PCM in a novel designed container. The findings highlight the importance of AR in mitigating the effect of the inclination angle on energy storage capacity. Additionally, comparing aluminium and plexiglass containers provides insights into the effect of container material on the melting behaviour and energy storage properties of PCM.

Experimental and numerical analyses were performed to investigate the control parameters of a Phase Change Material (PCM) melting by impinging a hot air jet. A novel container was designed to store PCM. The RT25HC was chosen as the PCM, with a 22-26 degrees C melting temperature. Experiments were conducted under a constant air temperature (Tair) of 40 degrees C with two different Reynolds (Re) numbers, 2235 and 4470. The analysis was performed for three jet length-to-container diameter ratios (H/D): 0.4, 0.5, and 0.6. The Finite Volume Method (FVM) was used to solve three-dimensional and time-dependent governing equations. It was found that the optimum melting time was attained when the H/D = 0.5. The measurements, thermal camera images and the numerical results displayed good agreement. The influence of H/D on the melting time decreases as the Reynolds number increases, decreasing the difference between the maximum and minimum melting rates from 23.05 % at Re = 2235 to 7.67 % at Re = 4470. In the experimental comparison, when considering H/D = 0.5, which corresponds to the case with the maximum stored energy at both Reynolds numbers, the energy stored by the H/ D = 0.6 cases is 26.4 % lower at Re = 2235. In contrast, this difference reduces to 5.03 % at Re = 4470.

Background: For balancing the imbalance between the energy supply and demand, phase-change materials (PCMs) provide an efficient means in terms of thermal energy storage and release. The performance of the energy storage is primarily dependent on the melting as well as the solidification process of the storage medium. Faster charging or discharging of the thermal energy is a primary concern for any thermal energy storage unit. On this background, the present study explores the novel approach for enhancing the solidification process of PCM considering the effects of cooler shape (namely semi-circular, triangular, and rectangular) and their position (namely top, side, and bottom) in a molten PCM-filled enclosure. The middle portion of the cooler wall is curved; whereas the remaining cooler wall is straight maintaining the same cooler wall length. Methods: To analyze the solidification process, the involved transport equations are solved numerically following a finite volume-based computational approach using Ansys Fluent solver in conjunction with the appropriate boundary conditions. The computational model is generated for all the geometry comprising different shapes, as well as positions of the cooler wall. The third-order upwind scheme (QUICK) technique is utilized to discretize the momentum and energy equations. This scheme is well capable to accurately capture the gradients in the temperature and flow domains. Furthermore, the semi-implicit pressure-linked equation (SIMPLE) technique is utilised to address the pressure-velocity coupling. The resolved data are then saved as selective variables (U, V, and theta), which undergo post-processing to produce a local thermo-fluid flow field and extract average data. Significant findings: The shape, as well as the position of a cooler, dictates the solidification process in an energy storage system. Thermal energy storage with a triangular-shaped cold wall positioned at the top could be opted as an appropriate design approach of an efficient energy storage system compared to a semi-circular or rectangular-shaped cooler model. The shortest solidification time of PCM occurs when the cooler wall is positioned at the top. The top position of the cooler having a triangular shape with higher Grashof number (Gr) values leads to a faster solidification process. Some ideas for possible future research areas in this field are provided after a comprehensive examination.

Thermal energy storage (TES) allows to the conservation of energy, enhancing the overall system efficiency and balancing the supply and demand of energy. This article presents a computational analysis of the solidification process of melted paraffin wax phase change material (PCM) through a partially heated backward-facing step channel partially cooled from the bottom and top. Melted PCM enters through the left opening of the step channel and leaves through the right opening. The study examines two distinct cases: considering sharp stepped or angular corner, and stepped or streamlined corner (of radius r = 20 mm) with the same inlet flow and boundary conditions. A comprehensive numerical model is developed and solved using the finite volume-based computational approach. The overall thermal performance of the model during the solidification process is evaluated for the different Reynolds numbers (Re = 20 and 40) and temperature differences (Delta T = 20 and 25 degrees C) for the different time steps. Furthermore, the effect of backward step curvature on the solidification process is also analyzed. The results revealed that all the parameters (Re, Delta T, and curvature) affect the melted PCM flow structure as well as the solidification process inside the channel. Changing the sharp step corner into a streamlined one at the bottom of the channel led to the lowest lesser flow separation and faster solidification process. Therefore, a well-designed streamlined step corner and its shape could be used to increase the discharging speed of thermal energy storage units meaningfully. Furthermore, such designs, the placement of the heater and cooler location, and step curvature are the guiding factors for controlling the performance of the energy storage. With the change in the curvature, the energy efficiency can be increased and the solidification time is lowered by at least 5 %.

Purpose This study aims to focus on understanding how different jet angles and Reynolds numbers influence the phase change materials’ (PCMs) melting process and their capacity to store energy. This approach is intended to offer novel insights into enhancing thermal energy storage systems, particularly for applications where heat transfer efficiency and energy storage are critical. Design/methodology/approach The research involved an experimental and numerical analysis of PCM with a melting temperature range of 22 °C–26°C under various conditions. Three different jet angles (45°, 90° and 135°) and two container angles (45° and 90°) were tested. Additionally, two different Reynolds numbers (2,235 and 4,470) were used to explore the effects of jet outlet velocities on PCM melting behaviour. The study used a circular container and analysed the melting process using the hot air inclined jet impingement (HAIJI) method. Findings The obtained results showed that the average temperature for the last time step at Ф = 90° and Re = 4,470 is 6.26% higher for Ф = 135° and 14.23% higher for Ф = 90° compared with the 45° jet angle. It is also observed that the jet angle, especially for Ф = 90°, is a much more important factor in energy storage than the Reynolds number. In other words, the jet angle can be used as a passive control parameter for energy storage. Originality/value This study offers a novel perspective on the effective storage of waste heat transferred with air, such as exhaust gases. It provides valuable insights into the role of jet inclination angles and Reynolds numbers in optimizing the melting and energy storage performance of PCMs, which can be crucial for enhancing the efficiency of thermal energy storage systems.

This study investigates the effects of partial porous blocks integrated in a phase change material (PCM) in a rectangular cavity on the thermal performance of the system. Computational fluid dynamics simulations were used but validation was done by using experimental set-up and measurement of the results. Different thermal conditions of evolution effects of different configurations such as porous block orientation, number and porosity on the melting behaviour and energy storage capacity of PCM. For the base case, experimental and computational fluid dynamics results are well consistent. The analyses revealed that the horizontal placement of porous blocks significantly increases the melting rate and energy storage efficiency compared to the alone PCM. At ΔT = 15 °C, t = 160 min, the energy stored in the one-part horizontal porous block (1P-HPB) configuration is 11.17

Three dimensional analysis of melting performance of phase change materials in a disk-shaped container with partial circular heating has been studied. The phase change materials (PCMs) have succeeded in coming to the fore with their superior features in energy storage. However, the energy storage efficiency of these materials affected by many physical parameters, and determining the appropriate parameters is important for efficient energy storage. This study explores melting and energy storage performance of PCM-RT25 in a disk-shaped container with various partial circular heating cases and aspect ratios (AR). PCM melting analysis was performed with partial heating by selecting equal heating surface area on the disk. The effects of AR on melting performance were analyzed by observing the PCM melting behavior for different disk heights while keeping the disk diameter constant. Governing equations are solved by using finite volume method. Obtained results showed that the PCM melting time decreases as the AR increases in the case of full heating. In partial heating, the increase in AR not only extended the melting time, but also decreased the liquid fraction at the end of the melting. Parameters of AR = 4 and Delta T = 45 degrees C was provided the maximum liquid fraction in partial heating cases. Under these conditions, 90%, 94% and 96% liquid fractions were obtained at the end of melting for the cases that the heater is located in the center of the disk, in the middle near the inner part of the disk and in the middle near the outher part of the disk, respectively.

Bu calismada, cekirdek yapisi ve yuzey kapaklari karbon fiber kompozit malzemeden olusan sandvic levhalar uretilmis ve cekirdek hucreleri poliuretan kopuk ile doldurulmustur. Sandvic kompozitlerin hucreleri kare kesitli olup cekirdek yapi uretimi, herhangi bir yapistirici malzeme kullanilmadan yapilmistir. Uretimi tamamlanan numunelere, basma ve uc nokta egme testi uygulanarak kuvvet-yer degistirme grafikleri elde edilmistir. Sonucta numunelerin basma ve egilme dayanimlari hesaplanmis ve hasar davranislari incelenmistir. Elde edilen sonuclar grafikler halinde sunulmustur. Deneysel calismalardan elde edilen sonuclara gore, cekirdek yapi hucre bosluklarinin kopukle doldurulmasi, sandvic levhalarin basma ve egilme dayanimlarini onemli oranda etkilememis, kismi olarak azalmasina neden olmustur

In this study, manufacturing of sandwich plates which are made of entirely carbon fiber composite reinforced epoxy resin material was carried out. Core structure of sandwich plates are square crosssection and core structure was fabricated without any adhesively materials. The force-displacement values were saved by applying an edgewise compression test with the help of universal tensile test machine. Then, edgewise compressive strengths of specimens having different cores height and density were calculated and presented as graphical. In the numerical study, edgewise critical buckling loads were calculated in the ANSYS program and the results were compared with experimental data.

Bu çalışmada, çekirdek yapısı ve yüzey kapakları karbon fiber kompozit malzemeden oluşan sandviç levhaların imalatı gerçekleştirilmiştir

In this study, mechanical properties of new-manufactured sandwich composites with various cell structures, having carbon fiber core have been investigated both numerically and experimentally. Three-point bending and compression tests are applied to the specimens as the experimental test approach. Failure behavior and strength of the specimens are extracted as a result of the measurements. The test results also give the opportunity to find out the optimum peak load/density ratio of various core types of sandwich composites. The commercial finite element software ANSYS has been used for numerical analysis. It should be remarked that a good agreement between numerical and experimental results is obtained. The cell shape and height are important parameters on peak load for bending. Additionally, change of cell density is a parameter having effect in same proportion for bending and compression peak loads for these type composites.