Heat Thermal Energy Storage System Research Articles

Cascading latent heat thermal energy storage in parabolic trough solar collector as a promising solution: An experimental investigation

Solar energy system can be considered as a reliable energy source if it connects to a latent heat thermal energy storage (LHTES) system using phase change materials (PCMs). To tackle the low thermal conductivity coefficient of PCMs, the cascaded latent heat storage (CLHS) configuration is a promising solution. This study aims to illustrate the improvement of CLHS setup comparing with non-cascaded arrangement, performing a whole-scale experimental investigation. A compact parabolic trough collector (PTC) unit equipped with a LHTES module is designed and constructed for a residential purpose. Experimental results reveal that the average thermal efficiency of PTC is 73.5 %. Three paraffin waxes with melting ranges of (64–68 ℃), (57–60 ℃) and (46–48 ℃) are injected in three same series of shell-tube heat exchangers. For comparing cascaded and non-cascaded PCM performance, three experimental series, namely (Exp.1, Exp.2 and Exp.3) are performed. The experimental findings show that the deployment of the CLHS configuration improves the latent heat storage of non-CLHS-Exps.1, 2, and 3 by more than 10, 47, and 5 %, respectively. In addition, CLHS system has a potential to increase the exergy storage of non-CLHS setup by up to 27.4 %. Furthermore, impact of increasing heat transfer fluid (HTF) flow rate is examined and it is observed that the melting process is shortened by almost 39 %. Accordingly, increasing flow rate improves energy stored in PCMs1, 2, and 3 by 60 %, 59.62 %, and 72.04 %, respectively. Consequently, the latent thermal exergy storage of the PCM experiences a twofold increase. Conducting an experimental evaluation of thermal performance of the storage module integrated with PTC setup can be valuable, particularly in the realm of residential applications.

Numerical study on the discharging performance of a latent heat thermal energy storage system with fractal tree-shaped convergent fins

In this paper, an innovative fractal tree-shaped convergent fin (FTSCF) is embedded into a latent heat thermal energy storage system (LHTESS) to numerically investigate the parametric influences of FTSCF including FTSCF number N, maximum branching level m, length ratio α, branch convergence β, level convergence γ, rotation angle δ of the branch at the outermost level and branching angle θu on the discharging performance of the LHTESS under the fixed total fin volume. The results imply that increasing N, m, and α significantly reduces the complete solidification time τ of the phase change material (PCM). Further, the τ of the PCM demonstrates a pattern of initial decrease followed by an increase under the influences of β, γ, and δ, indicating the presence of an optimal FTSCF structure maximizing the discharging efficiency of LHTESS. Compared to the fins without branch convergence, the minimum τ of PCM within the LHTESS reduces by 4.33 %, 5.03 %, and 12.42 % by the branch convergence β when γ = 0.5, 0.707, and 1. In addition, the minimum τ of PCM monotonically decreases when θ1 = θ2 increases from 50° to 90°. The present work provides a technique to improve the discharging performance of the LHTESS by using fin convergence.

Experimental study on the thermal characteristics of a visualized shell-and-tube LHTES system at different endothermic and exothermic temperatures

This research developed a novel medium-temperature (up to 300 °C) latent heat thermal energy storage (LHTES) system, utilizing a compact shell-and-tube thermal exchange system containing spiral finned tubes, 220 kg of phase change material (PCM) was employed, enabling 44.52 MJ of heat storage, a visible window allowed to observe the phase change process and investigate the temperature variations in conjunction with thermocouples. The study analyzed the thermal traits and explored the impact of charging and discharging temperatures on the system's thermal performance.The outcomes indicated that natural convection gradually supplants heat conduction in the charging process as the primary heat transfer mechanism and a temperature stratification phenomenon emerges within the TES; during the discharging process, a contrasting behavior is observed. Employing charging-discharging temperature configurations of 290-170, 280-160, and 270-150 °C, the cumulative energy input to complete the cycle process is 63.59, 56.43, and 54.87 MJ, correspondingly, the released energy is 33.64, 33.41, and 33.57 MJ, yielding cycle efficiencies of 52.90, 59.20, and 61.20 %, respectively, with the charging temperature rising from 270 to 290 °C, storage time decreased 25.6 %, but lead to an 8.49 % decrease in heat storage efficiency, while the discharging temperature has a relatively minor influence on the system.

Investigation of the thermal exchange mechanism of PCM melting process in an LHTES with elliptic tube configurations inside a cylindrical shell

This study presents a comprehensive 2D numerical investigation into the heat transfer mechanisms and melting time estimation for a phase change material melting process in latent heat thermal energy storage systems. The energy storage system of interest employs an elliptic tube configuration within a cylindrical shell. This study primarily aims to decipher the impact of spatial arrangement and its geometrical intricacies on melting time and the associated heat transfer mechanisms. First, this study examines the transition in the dominant heat transfer mechanisms, from conduction to natural convection, throughout the progression of the melting process. The examination is facilitated using the enthalpy porosity method, which can articulate an additional momentum term by leveraging the porosity at the melting interface and the local liquid fraction. Conduction dominance characterizes the early stages of the melting process; however, a transition toward a complex interplay of natural convection and conduction is observed as the process evolves. When the distance between the heat source and the outer covering is changed from a measure of 0.95 to 0.7, the time it takes for phase change material to melt increases by 73.2%. Additionally, when the shape of a certain heat transfer fluid carrier cylinder and the space between them in angles (from 1/8 to 8 and from 30° to 150°) are adjusted, the melting time changes by 31.1% and 38.9% respectively. In addition to the numerical analysis, this study introduces an innovative predictive model based on artificial neural networks to forecast the melting time of the phase change material in the energy storage system. This predictive model is trained and validated using the data derived from the numerical study and shows good accuracy in predicting the melting time, which is a critical factor for the efficiency and performance of systems.

Solar-driven chemisorption cogeneration system integrated with thermal energy storage

In this study, a power and cooling cogeneration system is introduced, consisting of a chemisorption cycle, a latent heat thermal energy storage (TES) system employing phase change materials (PCM), and a solar system employing compound parabolic collectors (CPC). The system is targeted at being employed in a residential area in Shiraz City and TRNSYS and MATLAB software environments are utilized to simulate and assess the system. In the system, power is generated by a turbine with the pressure difference elicited through the chemical reaction in the chemisorption cycle. Also, the cooling is produced via the evaporation of ammonia in the evaporator. The effect of the supplied hot source temperature for the reaction in the adsorbent bed was investigated. It was observed that in the 100–200 °C heat source temperature range, the total energy efficiency increased from 0.313 to 0.467 and the COP for the refrigeration process reduced from 0.71 to 0.53. Also, the maximum overall energy and exergy efficiency in this temperature range were 0.46 and 0.405, respectively. Also, at the heat source temperature of 200 °C, the average maximum electrical power and cooling capacity were gauged at 2.7 kW and 14.5 kW, respectively. In the TES system with a volume of 1.5 m3, the maximum achievable capacity was 250 kWh and the solar system showed its highest temperature in July and August. It was observed that heat source temperature augments the production capacity of the system while it reduced the coefficient of performance (COP) of the system. Sustainable development goals (SDG) impact [Display omitted]

Melting enhancement of latent heat thermal energy storage by implementing new geometric design

Latent heat thermal energy storage systems can manage peak energy demand with the unique thermo–physical properties of phase change material. However, the primary concern of using these systems is their low heat transfer rate. The present study attempts to increase the thermal performance of these systems using perforated stair fins and changing the enclosure’s geometry. For this purpose, parametric studies have been conducted to assess the effect of perforations on fins with different diameters (from dimensionless diameters of 1 to 2) and different numbers of perforations (from 6 to 24). Next, the effect of changing the enclosure's geometry to a parallelogram, trapezoid, and rectangle is investigated. Finally, by simultaneously applying the above–mentioned ideas, the performance parameters of the system are calculated and compared with the base case (enclosure with simple stair fins). The investigations are conducted using the finite volume method, and the material melting process is carried out based on the enthalpy–porosity method. All the simulations are three–dimensional and transient, with variable properties of material in solid and liquid phases. According to the results, using perforated fins intensifies the buoyancy force by increasing fluid displacement inside the enclosure. As a result, using 24 perforations on each fin with a D/δ = 2 improves the liquid fraction up to 9.7%. Moreover, the change of geometry reduces the critical area at the bottom of the system and improves the liquid fraction up to 5.4% inside the trapezoidal enclosure. By applying two ideas of using perforated fins and changing the geometry simultaneously, the mean Nusselt numbers for rectangular, trapezoidal, and parallelogram enclosures are significantly enhanced by 95, 114, and 133%, respectively. In these cases, the improvement in the heat transfer rate has led to a decrease in the melting time of the materials by 44.5, 47.5, and 51.5 min, respectively. These operational suggestions also enhance the critical performance parameters of the system, namely the stored energy and the mean charging power from 946 kJ/m and 124 W/m (in the base case) to 963 kJ/m and 211 W/m (70%) (in the rectangular enclosure with perforated fins).

Heat Transfer and Thermal Energy Storage Enhancement by Foams and Nanoparticles

The use of innovative methods for the design of heating, cooling, and heat storage devices has been mainly oriented in the last decade toward the use of nanofluids, metal foams coupled with working fluids, or phase change materials (PCMs). A network of nine Italian universities achieved significant results and innovative ideas on these topics by developing a collaborative project in the last four years, where different approaches and investigation techniques were synergically employed. They evaluated the quantitative extent of the enhancement in the heat transfer and thermal performance of a heat exchanger or thermal energy storage system with the combined use of nanofluids, metal foams, and PCMs. The different facets of this broad research program are surveyed in this article. Special focus is given to the comparison between the mesoscopic to macroscopic modeling of heat transfer in metal foams and nanofluids, as well as to the experimental data collected and processed in the development of the research.

Techno-economic assessment of the solar-assisted heat pump latent heat thermal energy storage system for water heating

A novel solar-assisted heat pump heating system including the latent heat thermal energy storage component that enables flexible switching between different connection modes was developed in this study to provide a cost-effective and energy-efficient solution for hot water supply. The feasibility, energy efficiency, and economic performance of the system under different design parameters and operation modes were evaluated via the experimental validated numerical model of the heating system. The end-user loads and meteorological parameters highly affected the system performance under the same design scheme. The optimal system configuration and component size for promoting renewable energy penetration and decreasing electricity cost were further determined. A certain increment in the collection area substantially benefits system performance, resulting in an approximately 56.6 % reduction in energy consumption. The larger capacity of the heat pump reflects a slight improvement in the system performance; however, it would require a longer payback period. Compared with the single solar and air heat source, the energy consumption of the hybrid heat source system declined by 26.6 % and 68.0 %, respectively. The system implementing the demand-side management proved to be a more profitable solution, exhibiting a low carbon emission of 188.1 kg, significant potential to flatten peak load, and a large lifecycle cost saving of $1834.64.

A CFD results-based reduced-order model for latent heat thermal energy storage systems with macro-encapsulated PCM

Macro-encapsulation of phase change material (PCM) is a promising approach to overcome a serious drawback of many latent heat thermal energy storage systems (LHTESSs): their low thermal power. Simulations are often used to support the design of these storage systems, but the simulation of the charging process of such an LHTESS with detailed CFD models is too computationally expensive. To obtain information about the behavior of a complete LHTESS, highly simplified system simulation models are usually applied. A new approach to create a reduced-order model is herein presented that aims to increase the accuracy of these system simulation models. The first step consists of performing a set of detailed CFD simulations of one capsule with different boundary conditions. The results are written into look-up tables that contain the charging power of one capsule as a function of the enthalpy stored and the boundary conditions. These look-up tables are then implemented into the reduced-order model. The temporal mean deviation of the energy content in the storage unit between experiments and the reduced-order model is only 5 % and the simulation time of the fastest reduced-order model was 5 s, while the CFD simulations took up to about two weeks on a workstation. Finally, for the conditions tested, the heat transfer fluid (HTF) does not have to be included in the CFD simulation, but can be replaced by a properly defined convective boundary condition. The capsule wall, however, needs to be included in the CFD model (especially for capsule wall materials with a distinctively higher thermal conductivity than the PCM) to account for the heat flow towards the bottom of the capsule supporting close contact melting.

An in-depth study on melting performance of latent heat thermal energy storage system under rotation mechanism by fluctuating heat source

The Organic Rankine Cycle (ORC) is a reliable and efficient means of converting solar energy into electricity. The challenges brought about by the unpredictable nature of solar energy can be effectively mitigated by utilizing latent heat thermal energy storage (LHTES) technology, specifically by implementing heat source pretreatment. This paper investigates the thermal storage properties of a rotating triplex-tube LHTES unit under different sinusoidal fluctuating heat sources. A transient numerical model is built to analyze the effects of sinusoidal wall temperature amplitude and angular velocity on the melting characteristics of the unit, including melting time, heat storage rate, and temperature response. The design is further analyzed using the Taguchi method. The results show that the angular velocity of the sinusoidal wall temperature has a greater effect on the average heat storage rate and melting time than the amplitude. When the amplitude is set to 10 and the angular velocity to 0.02, the melting time is decreased by 8.7%, while the average heat absorption rate and average temperature response increase by 10.21% and 12.27%, respectively. Additionally, the sensible and total heat energy absorption increase by 2.23% and 0.62%, compared to the initial heat source condition. Furthermore, the heat transfer is enhanced through the introduction of Al2O3 nanoparticles at varying percentages. The unit heat storage rate improves significantly with an increasing percentage of nanoparticles. Specifically, when 2.5% and 5% Al2O3 nanoparticles are added, the melting time of the unit is reduced by 3.77% and 15.07%, respectively, while the average heat absorption rate increases by 2.43% and 10.39%.

Optimizing fin design for enhanced melting performance in latent heat thermal energy storage systems

The addition of fins to phase change material (PCM) in latent heat thermal energy storage (LHTES) systems is a widely employed technique to enhance thermal performance and significantly improve energy storage efficiency. This research focuses on a two-dimensional numerical model investigating heat transfer within a shell-and-tube structure of LHTES. Various combinations of fin number and fin height were explored to assess their influence on melting performance while maintaining the consistent fin volume. Subsequently, a topology optimization technique was developed to determine the most effective fin configuration. The optimized fins exhibited dendritic distributions and outperformed other fin designs in terms of heat transfer performance. The topology-optimized design resulted in a remarkable 74 % increase in melting performance compared to the structure without fins. Furthermore, we introduced a simplified model that takes into account manufacturing feasibility. We verified that a fin volume fraction of 6 % resulted in a significantly reduced melting time of 36 min, in stark contrast to the 249 min observed without fins.

A novel design of heating system using phase change material for passenger car cabin in cold starting conditions

In this paper, the use of exhaust waste heat energy stored in a latent heat thermal energy storage (LHTES) system for cabin heating of a passenger car at cold climate conditions was investigated by experimental and computational fluid dynamics (CFD). A liquid circulation system was installed for this purpose, consisting of two heat exchangers, one in the passenger car's rear compartment and the other in which the phase change material (PCM) in the LHTES system was stored. Commercial RT55 paraffin wax was used as PCM, and tap water was used as heat transfer fluid (HTF). Experimental and CFD analysis studies, which started at 283 K cabin interior temperature, were continued for 1500 sec (25 min). Before the experiments, the cabin interior of the passenger car was cooled up to 283 K with the air conditioning system, and the air conditioning system was kept on at a setting where the cabin interior temperature would remain constant at 283 K during the experiments. Thus, real cold climate conditions were provided for the experimental study. As a result, it has been observed that with the new cabin heating system, thermal comfort conditions for people are provided after the first five minutes, and this temperature can be maintained throughout the experiment. So much so that the cabin temperature increased from 283 K to 295 K in five minutes and reached approximately 297 K at the end of the experiment with a slow rate of increase. Furthermore, the difference in RT55 temperatures between the experimental and CFD analysis results is less than 3% during the cabin interior heating period.

Enhancing the Power Performance of Latent Heat Thermal Energy Storage Systems: The Adoption of Passive, Fractal Supports

We employ a three-phase thermal lattice Boltzmann model (LBM) to investigate the power performance of latent heat thermal energy storage (LHTES) systems based on the exploitation of phase change materials (PCMs). Different passive thermal supports are considered to increase the melting rate, including innovative, fractal, branch-like structures. Our simulations reveal that the adoption of fractal, branch-like metal supports consistently outperforms other configurations in terms of PCM melting rates. These results open the path towards novel strategies to enhance the power performance of PCM-based TES systems, offering potential benefits for energy storage applications.

Experimental investigation of the solar latent heat thermal energy storage system integrated with salt hydrate phase-change materials

To achieve rational utilization of renewable energy sources, a solar latent heat thermal energy storage system for hot water application was developed in this study. The feasibility of the salt hydrates using in the solar heating was assessed and the comparative experimental investigation was conducted under various operating conditions. It shows that the higher flow rate and radiation accelerate the melting process of the phase-change material. The time taken for the storage medium to reach phase transition was reduced by approximately 48.9%; meanwhile, the collector efficiency was enhanced by approximately 10.2% as the flow rate increased from 10 g/s to 30 g/s. The accumulated charging energy increased by approximately 10.9% when the radiation increased from 850 W/m2 to 920 W/m2, resulting in a prolonged heat release process. The test results suggest the promising potential of the salt hydrates for the solar water heating applications.

Prediction of the discharging time of a latent heat thermal energy storage system with a UA approach

Designing latent heat thermal energy storage systems is a cumbersome task and the estimation of the performance of such a storage system normally involves experiments and detailed numerical simulations. Analytical, empirical and simplified numerical models are much faster but subject to large uncertainties. Even the prediction of the performance of an existing latent heat thermal energy storage system under different boundary conditions is often not possible in an easy way. Therefore, we present an analytical method – the UA approach – to predict the discharging (solidification) time of a flat plate latent heat thermal energy storage system. A special feature of the UA approach is that one can incorporate experimental or numerical results to improve the prediction of the performance under a variety of boundary conditions or material properties. The UA approach was tested for a variation of the Stefan number (Ste), the Biot number (Bi), the number of transfer units (NTU) and the heat transfer fluid and was compared to the results of a validated numerical model. The results are promising, especially for small Ste. In addition, the prediction of performance for a high thermal heat conductivity of the phase change material based on a numerical reference solution with a low thermal conductivity worked remarkable well.

Latent heat thermal energy storage in a shell-tube design: Impact of metal foam inserts in the heat transfer fluid side

The improvement of heat transfer in latent heat thermal energy storage (LHTES) system is a crucial task. In the current study, the impact of diverse metal foam (MF) layer arrangements on heat transfer fluid (HTF) within a shell-tube LHTES is explored. Six distinct cases (A-F) with varied MF coverage percentages and layer dimensions were assessed. The local thermal non-equilibrium model was utilized to take into account the PCM and MF temperatures. The finite element method was used for solving the partial differential equations. The impact of MF configurations and inlet pressures (250 Pa, 500 Pa, and 750 Pa) on the thermal energy storage/release was addressed. Cases A-C, featuring a 50 % MF concentration, exhibit shorter melting times than Cases DF, with decreasing MF concentrations. A higher MF concentration improves the melting process due to increased thermal conductivity and lower thermal resistance on the HTF side. Cases DF, with a centralized MF layer and decreasing concentrations from 25 % to 6.25 %, display progressively shorter melting times, suggesting that a lower MF concentration leads to more efficient melting. Solidification times also decrease with increasing inlet pressures across all cases. Reynolds numbers, influenced by average HTF tube outlet velocity, vary substantially across cases and inlet pressure differences. Cases A-C demonstrate similar Reynolds numbers for each inlet pressure difference, while Cases DF show a more pronounced increase in Reynolds numbers as the MF layer is reduced and flow resistance drops. Cases A (50 % MF layer) and F (6.5 % MF layer) provide the quickest charging and discharging times due to their unique combination of MF layer properties and inlet pressures. The study highlights the need to consider MF layer composition and inlet pressure when designing optimal LHTES systems for efficient energy storage/release.

Numerical investigation of melting of a phase-change material in H-type shell tubes

This study aims to numerically investigate the melting process of a phase change material in an H-type finned concentric shell tube configuration. The H-type fins are arranged in a manner that creates an annulus structure consisting of six identical H-type fin structures. These fins are evenly spaced with equal distances between them. The phase change material used in this study is RT42, which is stored within the annulus structure to absorb heat from the inner circular tube at a constant temperature input of 70 °C. The results of the study demonstrate that the phase change material within the H-type fin tube, with a uniform width of 3 mm, exhibit significantly faster melting rates compared to narrower fin tubes. Specifically, the phase change material in the 3 mm fin tube demonstrate melting rates that are 88% and 32% higher than those observed in fin tubes with widths less than 1 mm and 2 mm, respectively.Furthermore, the study considers two additional geometric factors, namely the varying curvy angles of the first and second circular layers of the H-type fins. Melting behavior is numerically featured by varying the ratios of these curvy angles within the range of 0.68 to 1.53. Among all the H-type annulus structures of the present study, the ratio of 1.21 is the most suitable design for increasing the total energy stored, while the ratio of 1.32 is an adequate choice for improving melting performance. Additionally, the latter ratio results in a 1.68 times reduction in melting time compared to the ratio of 1. Properly arranged H-type fin structures are possibly considered a preferable design that can either enhance heat transfer or increase the total stored energy, possibly expanding PCM applicability to a more latent heat thermal energy storage systems of practical interest.

Development of an integrated waste heat recovery system consisting of a thermoelectric generator and thermal energy storage for a propane fueled SI engine

In this paper, an integrated waste heat recovery system consisting of a thermoelectric generator and a latent heat thermal energy storage system was constructed to convert the wasted heat energy in a spark-ignition engine into useful energy. The TEG used in the integrated system has a three-layer structure formed of two cold-side heat exchangers placed on the upper and lower surfaces of the rectangular mid-exhaust heat exchanger. A total of 2x12 = 24 pieces of TEM were used between the lower and upper TEG_ec_hex and mid-TEG_ex_hex. For LHTES, a 3-layer heat exchanger consisting of a vertical copper tube placed in the middle of two cylindrical coils in a cylindrical tank with a diameter of 280 mm and a height of 350 mm was used. Three different configurations (Case_1, Case_2 and Case_3) were designed for the integrated system, in which exhaust gases, engine coolant, and HTF are used in different combinations. As a result, while the TEG_power is 69.395 W in Case_1, it decreases to 64.375 W in Case_2 and 62.417 W in Case_3. The total energy generated in the TEG at 7200 s is 500.27 kJ, 463.99 W, and 449.97 kJ for Case_1, Case_2, and Case_3, respectively. The stored energy in PCM_hex at 7200 s is 1372.91 kJ in Case_1, but it increases to 2255.16 kJ in Case_2 and to 2559.39 kJ in Case_3. While the fuel energy recovered by the integrated system is 1.03% in Case_1, it increases to 1.49% in Case_2 and 1.66% in Case_3.

Investigation of packed bed pouches filled with phase change material for air heating

Latent heat thermal energy storage system has high energy storage density and uses phase change materials; thus, it is an essential device for utilizing intermittent renewable energy, such as solar heat. Recently, research on demand management of building heating energy using latent heat thermal energy storage has gained increasing attention. Latent heat thermal energy storage-based building thermal energy management is advantageous for space heating that directly heats indoor air; in particular, improving the heat transfer rate of phase change materials and reducing the total melting time to maximize the system performance are attracting attention. In this study, a packed bed pouch system for air heating was developed, and its charging and discharging performance was analyzed using experimental and numerical methods. The packed bed pouches were filled with n-octadecane as a phase change material, and the thermal performance was investigated through a parametric study. During the experiment, the temperature and melting fraction in the single pouch were measured over time, and the reliability of the numerical results was validated. Consequently, a temperature increases of 22 ℃ was measured during 10 h of charging with an air flow rate of 0.009 kg/s. The amount of thermal energy and rate of heat transfer for the charged and state were 2.1 MJ and 55 W, and those for the uncharged state were 0.91 MJ and 42 W, respectively. In addition, in the case of the unaligned layout, the Nusselt number increased by 21.8% and phase change material melting duration was 15% shorter, as compared with the case of aligned layout. Finally, indoor heating using the heating chamber was performed. In the discharge experiment, air at 30 ℃ was supplied to the heating chamber at a flow rate of 0.009 kg/s; consequently, the temperature of the heating chamber increased by 15 ℃, from 5 to 20 ℃, and then remained constant for 30 min. In conclusion, the performance and utility of the air-type packed bed pouch system developed in this study were confirmed.

Physics-based modelling and data-driven optimisation of a latent heat thermal energy storage system with corrugated fins

Solid-liquid phase transformation of a phase change material in a rectangular enclosure with corrugated fins is studied. Employing a physics-based model, the influence of fin length, thickness, and wave amplitude on the thermal and fluid flow fields is explored. Incorporating fins into thermal energy storage systems enhances the heat transfer surface area and thermal penetration depth, accelerating the melting process. Corrugated fins generate more flow perturbations than straight fins, improving the melting performance. Longer and thicker fins increase the melting rate, average temperature, and thermal energy storage capacity. However, the effect of fin thickness on the thermal characteristics seems insignificant. Larger fin wave amplitudes increase the heat transfer surface area but disrupt natural convection currents, slowing the melting front progress. A surrogate model based on an artificial neural network in conjunction with the particle swarm optimisation is developed to optimise the fin geometry. The optimised geometry demonstrates a 43% enhancement in thermal energy storage per unit mass compared to the case with planar fins. The data-driven model predicts the liquid fraction with less than 1% difference from the physics-based model. The proposed approach provides a comprehensive understanding of the system behaviour and facilitates the design of thermal energy storage systems.