Solid Phase Change Material Research Articles

Flexibility, malleability, and high mechanical strength phase change composite films for solar-thermal and electro-thermal energy storage

Phase change materials (PCMs) are widely used in a range of energy storage applications due to high latent heat absorption and release capacities during phase change processes. There is still a lot to be done to resolve the inherent leakage, stiffness problems, and poor solar-thermal and electrical-thermal conversion capacities of PCMs to functionalize them. Here, a novel solid-solid phase change material (IGPCM) is created using block copolymerization. The IGPCM has a tunable enthalpy (from 58.16 to 99.60 J g−1) by adjusting the molecular weight of the PEG. The obtained IGPCM10K has high toughness (479.1 MJ/m3), excellent bending and malleability. Since IGPCM10K suffers from poor thermal conductivity, photo responsiveness, and electro-thermal conversion, carbon nanotubes (CNT) can be added to our IGPCM10K in a simple way to improve these issues. The thermal conductivity of IGPCM10K-CNT-3 is improved by 55.6 % compared to IGPCM10K. The photothermal conversion efficiency is 84.9 % at 300 mW/cm2. The electrothermal conversion efficiency is 82.3 % at 12 A. The prepared flexible PCM composites have super toughness, high enthalpy, excellent thermal conductivity, and photo-thermal and electro-thermal conversion capabilities, which will show great potential in future applications.

A novel photocurable polymeric solid–solid phase change material for intelligent temperature regulators

A novel photocurable polymeric solid–solid phase change material for intelligent temperature regulators

Integrating MXene Film With Recyclable Polyethylene Glycol-co-Polyphosphazene Copolymer as Solid-Solid Phase Change Material for Versatile Applications.

Phase-change materials (PCMs) stand a pivotal advancement in thermal energy storage and management due to their reversible phase transitions to store and release an abundance of heat energy. However, conventional solid-liquid PCMs suffer from fluidity and leakage in their molten state, limiting their applications at advanced levels. Herein, a novel Zn2+-crosslinked polyethylene glycol-co-polyphosphazene copolymer (PCEPN-Zn) as a solid-solid PCM through dynamic metal-ligand coordination is first designed and synthesized. The as-synthesized PCEPN-Zn is further integrated with an MXene film to construct a double-layered phase-change composite through layer-by layer adhesion. Owing to the introduction of MXene film with low emissivity, good light absorptivity, and nonflammability, the resultant phase-change composite not only presents a high latent-heat capacity, good thermal stability, high thermal reliability, and excellent shape stability, but also exhibits a superior self-healing ability, good recyclability, high adhesivity, and good flame-retardant performance. It can be easily adhered to on most objects for various application scenarios. With a combination of the excellent functions derived from PCEPN-Zn and MXene film, the developed phase-change composite exhibits broad prospects for versatile applications in the thermal management of CPUs and Li-ion batteries, thermal infrared stealth of high-temperature objects, heat therapy in the clinic, and fire-safety for various scenarios.

Experimental study on an improved direct-contact thermal energy storage container

Direct-contact thermal energy storage (TES) systems characterized by high heat density and rapid heat transfer rates have been exploited for the collection of industrial waste or surplus heat for subsequent utilization. In order to address blockage issue at the initial stage of charging process, an improved direct-contact TES container was developed by incorporating a double-pipe structure at both the inlet and outlet. Within the container, a U-shaped tube serving as the inner tube was concentrically positioned from the inlet to the outlet. Erythritol was selected as the phase change material (PCM), while heat transfer oil (HTO) functioned as the heat transfer medium during experimentation. During the charging process, hot HTO initially flowed through the U-shaped tube, establishing an indirect contact with the PCM. The high thermal conductivity of the U-shaped tube wall expedited the formation of a flow channel within the solid PCM. The duration of forming flow channel was 6 to 13 min. In the discharging phase, the liquid PCM was segregated into convection and conduction zones. The indirect-contact TES experiments were also conducted in the same container. Comparison between indirect-contact and direct-contact TES were analysed from the aspects of phase change behavior, charging and discharging time with the identical container structure and theoretical heat capacity. Results indicated that the direct-contact TES container exhibited superior heat storage and release rates, with the direct-contact discharging time being approximately a quarter of the indirect-contact duration. The phase change behavior of the PCM was notably influenced by the movement of HTO within the direct-contact storage container.

Discharging Performance Analysis of MXene Nano‐Enhanced Phase Change Material for Double and Triplex Tube Thermal Energy Storage

ABSTRACTThe present study numerically investigates the energy and exergy analysis of solidification of phase change materials within a double tube and triple tube latent heat storage unit using ANSYS Fluent. Double tube and triple tube thermal energy storage system's thermal characteristics are examined using MXene nano‐enhanced phase change material to determine system efficiency, discharged energy, heat transfer rate, exergy destruction, entropy generation number, exergetic efficiency, liquid fraction, solidification temperature contours. The result revealed that the double tube thermal energy storage with pure cetyl alcohol PCM has 14.76% lower discharge exergy than MXene‐based nano‐enhanced phase change material in pure solidification. In a triple tube thermal energy storage system, the solidification time for MXene‐based nano‐enhanced phase change material is impressively reduced by 54.76% compared to a double tube system using pure phase change material. At a Fourier number of 0.00672, MXene nano‐enhanced phase change material exhibits an 11.69% higher Stefan number (St) than cetyl alcohol phase change material in a double tube thermal energy storage system. At 2400 s, pure phase change material and MXene nano‐enhanced phase change material generated 3.14% and 4.88% less entropy than pure cetyl alcohol in the triple tube thermal energy storage system. During the pure solidification process in a double tube thermal energy storage system, pure cetyl alcohol experiences 7.60% higher exergy destruction compared to MXene nano‐enhanced phase change material at a solidification time of 2400 s. In a triple tube thermal energy storage system, the discharging temperature for pure cetyl alcohol phase change material is 2.92% lower than that in a double tube system. Double tube thermal energy storage with pure cetyl alcohol discharged more efficiently over 2400 s. The triple tube thermal energy storage system solidified cetyl alcohol PCM 20.83% faster than pure phase change material due to MXene nanoparticles' better thermophysical properties. Thus, MXene‐based nano‐enhanced cetyl alcohol phase change material solidifies faster per volume in a triple tube thermal energy storage latent heat system.

Enhancing building energy efficiency: Innovations in glazing systems utilizing solid-solid phase change materials

This study investigates the energy efficiency of a double-glazing window (DGW) integrating a solid–solid phase change material (SSPCM) with limited thickness, applied to the inner glass pane within the air gap. Numerical model, validated against experimental data, is developed using a finite volume method in ANSYS Fluent. In this model, the Discrete Ordinates (DO) model is applied to simulate radiation, while the enthalpy-porosity approach is used to capture the solidification and melting processes in the phase change material. With this model, the energy performance of the system is analyzed under various transient temperature values (10 to 30 °C) and ranges (1 to 5 °C) during the coldest and hottest days of the year, as well as during cloudy and sunny days in Montreal (Dfb), Vancouver (Cfb), and Miami (Aw). According to the obtained results in Montreal, the DGW-SSPCM system consistently saves energy under summer sunny conditions, with optimal performance when the SSPCM remains transparent. However, it incurs energy losses in cloudy days, where the energy lost is 2.3 times greater than the energy saved in sunny days. In Vancouver, the system shows consistent energy savings, particularly at Tc = 30 °C, with average savings of 20.5 kJ (23 %) under summer sunny conditions. The system is most beneficial in Vancouver, where winter energy savings in cloudy days (50.6 kJ) are 7.1 times greater than the losses in sunny days (7.1 kJ). In Miami, the system results in energy losses by 60 % and 5 % (at Tc = 30 °C) under both summer sunny and cloudy conditions, respectively, indicating unsuitability for its climate. During winter sunny conditions, all three cities experience energy losses, with Vancouver showing the lowest of 7.1 kJ (3 %) and Montreal the highest of 64.4 kJ (19 %) at Tc = 30 °C. In winter cloudy conditions, the system saves energy in all cities, with the highest savings in Miami of 54.5 kJ (26 %) at Tc = 30 °C. Overall, the SSPCM-DGW system has proven to be beneficial in Vancouver across various conditions in terms of energy and visual performance. These findings highlight the necessity of considering localized climate factors when designing and implementing energy-efficient glazing systems. Finally, the SSPCM-DGW system has provided complete visual clarity during office hours, making it more suitable for commercial buildings.

Two‐Dimensional Solidification Simulation of PCM Molten Salt as a Thermal Energy Storage for Stirling Engine

ABSTRACTThermal energy storage technologies have been widely used to mitigate intermittency from renewable energy sources such as solar energy. Phase change material (PCM) is a material that can be used as a heat storage medium and is available in a wide range of operating temperatures. Molten salt is one of the PCMs that has the advantage of a very high operating temperature. The PCM solidification simulation based on HitecXL molten salt using COMSOL Multiphysics software was carried out with variations in heat absorption of 1–5 kW/m2, assuming constant heat absorption. The results showed that the PCM solidification process started from the surface of the Stirling engine heat exchanger pipe. The part of the PCM that is solidified falls due to gravity, causing a phenomenon similar to a droplet. The flow that occurred was natural, driven by the buoyancy force resulting from density changes due to temperature gradients in the solidification process. The time required for the PCM to completely solidify was closely related to the amount of heat absorption; the greater the heat absorption from the pipe, the faster the PCM is fully solidified.

Photo-thermal effects initiate multi-level energy conversion in “solid-solid” phase-changing fibers

The current textiles primarily employ passive heat barriers to minimize heat loss and achieve effective thermal insulation for human beings. Accordingly, intelligent fibers with energy storage and temperature control capabilities have garnered significant attention due to their potential to revolutionize textile technology. The study integrates the photo-thermal effect and phase change energy storage materials onto a fiber, thereby fabricating a fully intelligent energy storage fiber. This innovation enables the multi-level conversion of sunlight: “Optical energy - Thermal energy - Phase transition energy - Thermal energy”. The intelligent fiber efficiently converts solar energy into heat energy through the photo-thermal coupling of CuNPs, subsequently inducing a spatial conformational change in the solid-solid phase change material within the fiber for effective heat storage. The hybrid fiber possesses enhanced mechanical properties but also exhibits a significantly high phase transition enthalpy value of 49.75 J g−1 and a phase transition temperature suitable for human body temperature (20.19–30.21 °C), especially the fiber is more durable. The photo-thermal conversion test vividly demonstrates the systematic transformation of four distinct forms of energy within the composite fiber. This approach holds significant potential for advancing the field of smart fiber technology.

Experimental and numerical investigation on the performance of binary solid-solid phase change materials with integrated heat pipe and aluminium foam based heat sink for thermal management of electronic systems

Phase change material (PCM) is widely utilised in thermal management systems (TMS), however its low thermal conductivity inhibits performance. Heat pipe and porous materials are incorporated into PCM due to their high thermal conductivities to form a hybrid system that substantially enhances PCM's heat transfer capability. This study investigates experimentally and numerically, the cooling performance of heat sink by integrating aluminium foam and heat pipe (HP) with binary Neopentyl glycol (NPG)/Trihydroxy methyl-aminomethane (TAM) solid-solid phase change material (SS_PCM) obtained at 90/10 wt% (N9T1), 70/30 wt% (N7T3) and 50/50 wt% (N5T5). Compared to pure NPG thermal conductivity, N9T1, N7T3, and N5T5 samples demonstrated relative enhancement ratios of 0.017, 2.46, and 2.84. Different heat sink configurations are examined at three constant power levels 15, 17 and 19 W for the same charging period of 10000 s to determine the optimal cooling arrangement. During the charging period, hybrid cooling (PCM-Foam-HP) system with fan in contrast to an empty sink achieved the highest temperature reduction of 58.31 %, 58.99 % and 59.89 % at power levels of 15, 17 and 19 W, respectively. N9T1, N7T3 and N5T5 combinations lowered temperature by 4.6 %, 5.9 % and 10.8 %, respectively, when compared to NPG. Furthermore, all configurations performed better at lower heat generation rates by extending the safe operational period (SOP).The investigation concluded that N5T5 SS_PCM-aided heat sinks with integrated aluminium foam and heat pipe with fan reduced temperatures the most and performed best in all aspects. Finally, the experimental results for TMS were numerically validated using COMSOL software.

Colossal Barocaloric Effect in Encapsulated Solid‐Liquid Phase Change Materials

AbstractBarocaloric cooling as an emerging cooling technology offers an eco‐friendly alternative to traditional vapor compression refrigeration. Research on barocaloric materials primarily concentrates on solid–solid phase change materials (PCMs), among which plastic crystals exhibit colossal barocaloric effect. Solid‐liquid PCMs such as paraffin also exhibit giant barocaloric effect, however, their potential is often overshadowed by leakage issues. In this work, a strategy is demonstrated by encapsulating solid‐liquid PCMs into porous carbon matrixes to generate a large family of colossal barocaloric materials. In practice, by orthogonally combining paraffins with encapsulation matrixes like graphene foam, carbon nanotube foam, and carbon foam, it can be obtained composites that work without leakage issues. The significant advantage is their colossal barocaloric effect with the highest entropy value up to 570 J K−1 kg−1 in paraffin‐20@graphene foam. Moreover, the composites possess thermal conductivity up to 89.9 W m−1 K−1 in paraffin‐20@carbon foam, and tunable working temperature in the range of 270—330 K. Most importantly, this strategy, demonstrated with 5 solid‐liquid PCMs and 3 encapsulation matrixes in this work, is just the beginning. Further exploration with more materials can develop a huge family of encapsulated solid‐liquid PCMs with colossal barocaloric performance for modern cooling technology.

Titanium dioxide/graphene oxide synergetic reinforced composite phase change materials with excellent thermal energy storage and photo-thermal performances

The development of advanced composite solid-solid phase change materials (SSPCMs) is urgent to explore for improving solar energy harvesting and storage. Herein, novel composite SSPCMs with synergetic cross-linking structure were fabricated through polymerization using GO and TiO2 constructed on the polyurethane framework skeleton. GO and TiO2 synergetic enhanced polymer framework played a role as skeletal structure to encapsulate PEG in the molecular chains, and provided as highly thermal conductive pathways for the composite SSPCMs. TiO2 nanoparticles performed as extended surface on the skeletal structure for further improvement in thermal conductivity. The composite SSPCMs exhibited a remarkably improved thermal conductivity as high as 0.7 W/(m‧K) and fast thermal response rate. The good light adsorption property of TiO2 enhanced the light absorbance efficiency of the composite SSPCMs by 94.4%. And the photo-thermal conversion efficiency of the composite SSPCMs highly reached 93.5%. Meanwhile, the composite SSPCMs exhibited excellent anti-leakage performance and shape stability under high temperature. Consequently, the as-prepared composite SSPCMs possessed a potential for applications in thermal energy storage and solar energy utilization systems.

A Computational Study on Utilizing Phase Change Material With a Condenser to Improve air Conditioning System Performance

ABSTRACTThe efficacy of employing multiple cylindrical phase change materials (PCM) to enhance the performance of an air conditioning (AC) unit is examined in this study. The objective of the present study is to examine the effects of combining an AC unit with a cylindrical PCM container configuration on the PCM discharge process and the performance of the AC system. The procedure involves the connection of a heat exchanger with a cold energy storage PCM to the condenser of the AC. During the daytime, the warm surrounding air is cooled and then transmitted to the AC unit's condenser. Four different turbulence models, that is, the SST , standard , Realizable and RNG have been considered for the present computational study. The investigation has been performed for different air flow rates, that is, 33.6, 42, and 49 for a constant inlet air temperature of 308.15 K. The present outcomes indicate that as the flow rate rises, the air temperature inside the domain increases and the solid PCM starts melting. It is noted that complete discharging time for multi‐cylindrical PCM reduces as the air flow rate rises which are around 13.36, 11.03, and 9.94 h for airflow rates of 33.6, 42, and 49 , respectively. The maximum achieved increase in the COP is around 94.49%, 88.68%, and 87.57% at airflow rates of 33.6, 42, and 49 L/s, respectively, for the multi‐cylindrical PCM throughout the summer. It is found that for the same temperature, as the airflow rate rises, the consumed power saving rises.

PCM-based passive cooling solution for Li-ion battery pack, a theoretical and numerical study

We propose in this study a novel cooling solution for Li-ion battery packs based on Phase Change Materials (PCM) and metallic fins placed around each cell. Discharging and charging processes both melt the PCM. To complete the thermal management of the batteries, an intermediary sequence is added for the PCM solidification. During a short timeframe between batteries charging and discharging, a liquid coolant flows through one small channel located within each fin. A numerical model and a theoretical analysis allow to predict the thermal behavior of the battery cells and the PCM liquid fraction changes in time. It is shown that the combination of a passive cooling solution brought by the PCM with the fast period of liquid cooling for the PCM solidification is an effective solution to control the temperature evolution within the battery cells during discharge and charge. The only external energy consumption foreseen comes from the laminar flow of the coolant for solidification during a very short period of time. The findings indicate that the proposed PCM-liquid cooling integration reduces the total energy consumption by 54.9 % (from 0.4406 kJ to 0.1963 kJ) for the 2C discharging-2C charging cycle compared to traditional liquid-cooling strategy.

Suitable material design of temperature-stabilizing device using phase change materials for electric power supply of nanosatellites

This study proposes a new passive thermal-control device utilizing phase-change materials (PCMs) that require minimal active thermal support, such as heaters, to achieve a high-performance and high-reliability power supply for nanosatellites and other space applications. This study evaluated two different PCMs as candidate materials for the device and compares their performances as thermal control devices. One was a solid–solid PCM based on vanadium dioxide doped with tungsten (VWO2), and the other was a microencapsulated PCM containing n-paraffin (NPH-MPCM). For integration into nanosatellites, it is essential to form a PCM as solid blocks. This report adopted a solidification method using epoxy resin (EP) as the binder and determined the optimal block composition for each PCM. The thermal-insulation properties of both PCM blocks in vacuum and low-temperature environments were evaluated and found to be almost equivalent. Considering that the latent heat of VWO2 is only approximately one-fifth that of NPH-MPCM, the practical application of VWO2 as a PCM was demonstrated. Furthermore, VWO2 exhibits a phase-change temperature hysteresis of 4 °C, which is significantly smaller than the 23 °C of NPH-MPCM. This characteristic is expected to help maintain a more constant temperature for power supplies in earth-orbiting micro/nanosatellites. Moreover, lithium-ion battery cells were incorporated into both VWO2-based and NPH-MPCM-based PCM blocks, and their charge–discharge behaviors were evaluated. Only the VWO2-based PCM block could maintain appropriate temperatures to ensure stable charge–discharge operation. Vacuum resistance results suggested that the VWO2-based PCM block is well-suited as a temperature-stabilizing device for electric power supplies in nanosatellites.

Theoretical study of solidification phase change heat and mass transfer with thermal resistance and convection subjected to a time-dependent boundary condition

The solidification of phase-change materials (PCMs) is a key process that occurs commonly in materials science and metallurgy, such as in the casting of alloys and energy management systems. There is a lot of literature in this area that assumes the PCMs are in close contact with the heat source or sink. However, a non-freezing wall frequently encloses them in practical situations. This work presents a phase change problem that describes the solidification of a semi-infinite PCM with thermal resistance. We assume that time-dependent heat flux drives the solidification process. The PCM first convert into mush and then into solid, which leads to a three-region problem. The current study accounts for both conduction as well as convection heat transfer mechanisms. Unfortunately, the exact solution to such problems with time-dependent flux-type boundary conditions may not be possible. Thus, there is considerable interest in deriving the analytical solution. The space–time transformation yields the analytical solution to the problem. A numerical example of Al−Cu alloy with 5%Cu is presented to demonstrate the current study. Thermal resistance shows a pronounced impact on the temperature field. Lower thermal resistance offers faster solidification rate. It is found that as the heat transfer constant increases, the rate of propagation of solid–mush and mush–solid interfaces gets enhanced. In addition, the growth of thermal resistance is of linear nature, with variation in the value of Q. The solidified region has higher concentration than the mush region. The current study is applicable to both eutectic systems and solid solution alloys.

Enhanced flame-retardant phase change materials with good shape stability for thermal management

Phase change materials (PCMs) have become pivotal components in many fields such as energy storage, thermal management, and photothermal conversion. However, challenges including leakage, flammability, and low thermal conductivity have impeded their broad application. In this work, a cross-linked solid-solid PCM (SPEG) using polyethylene glycol (PEG) and styrene-maleic anhydride copolymer (SMA) was synthesized. To enhance flame retardancy and thermal conductivity, black phosphorus (BP) and expandable graphite (EG) were introduced into the PCM matrix, yielding the target product (SPEG-BP/EG PCM) with enhanced properties. The analysis demonstrated that the SPEG-BP/EG sample with the ratio BP/EG of 1:1 (SPEG-BP/EG-1) exhibited a notable decrease in peak heat release rate and total heat release by 55.2 % and 13.2 %, respectively, compared to the SPEG sample. Moreover, thermal conductivity was improved from 0.18 W m−1 K−1 (SPEG) to 0.59 W m−1 K−1 for SPEG-BP/EG-1. The inclusion of SMA in crosslinking facilitated the transition of PEG's phase change behavior from solid-liquid to solid-solid, maintaining an enthalpy efficiency of 64.0 %. SPEG-BP/EG-1 exhibited excellent dimensional stability and cycling performance in open heating/cooling cycle tests, remaining chemically stable even after 60 heating/cooling cycles, as confirmed by DSC analysis. Furthermore, thermal management performance was evaluated using an LED light bulb, revealing a notable reduction of 9.4 °C in the maximal working temperature facilitated by SPEG-BP/EG PCM. This work presented a comprehensive strategy to mitigate the challenges of flammability, low thermal conductivity, and leakage associated with conventional PCM (PEG), thereby having great potential in practical applications in thermal management.

3D Numerical Modeling to Assess the Energy Performance of Solid–Solid Phase Change Materials in Glazing Systems

This research investigates the energy efficiency of a novel double-glazing system incorporating solid–solid phase change materials (SSPCMs), which offer significant advantages over traditional liquid–solid phase change materials. The primary objective of this study is to develop a 3D numerical model using the finite volume method, which will be followed by a parametric study under real climatic boundary conditions. A proposed double-glazing setup featuring a 2 mm layer of SSPCM applied on the inner glass pane within the air gap is modeled and analyzed. The simulations consider various transient temperatures and ranges of the SSPCM to evaluate the energy performance of the system under different weather conditions of Miami, FL during the coldest and hottest days of the year, both in sunny and cloudy conditions. The results demonstrate a notable improvement in energy performance compared to standard double-glazing windows (DGWs), with the most efficient SSPCM configuration exhibiting a phase transition temperature and range of 25 °C and 1 °C, respectively. This configuration achieved energy savings of 24%, 26%, and 23% during summer sunny, winter sunny, and winter cloudy days, respectively, relative to DGWs during cooling and heating degree hours. However, a 3% energy loss was observed during summer cloudy days. Overall, the findings of this study have shown the potential for energy savings by incorporating SSPCM with suitable thermophysical properties into double-glazing systems.

Simulation on solidification process of molten salt-based phase change material as thermal energy storage medium for application in Stirling engine

Abstract Thermal energy storage technologies have been widely used to mitigate intermittency from renewable energy such as solar energy. Phase change material (PCM) is a certain material that can be used as a heat storage medium and is available in a wide range of operating temperatures. Molten salt is one of the PCMs that has the advantage of a very high operating temperature. The PCM solidification simulation based on HitecXL molten salt using COMSOL Multiphysics software will be carried out with variations in heat absorption of 1 - 5 kW/m2, assuming constant heat absorption. The results show that the PCM solidification process starts from the surface of the Stirling engine heat exchanger pipe. The part of the PCM that has been solidified will fall following the direction of gravity and cause a phenomenon such as a droplet. The flow that occurs is a natural flow caused by the buoyancy force due to changes in density due to temperature gradients in the solidification process. The time required for the PCM to completely solidify is closely related to the amount of heat absorption. The greater the heat absorption from the pipe, the faster the PCM to fully solidified.

Expression of Concern for article entitled “Investigation of heat transfer, melting and solidification of phase change material in battery thermal management system based on blades height”

Expression of Concern for article entitled “Investigation of heat transfer, melting and solidification of phase change material in battery thermal management system based on blades height”

Effects of cooler shape and position on solidification of phase change material in a cavity

BackgroundFor 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. MethodsTo 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 θ), which undergo post-processing to produce a local thermo-fluid flow field and extract average data. Significant findingsThe 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.