Solidification Process Of Phase Change Material Research Articles

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.

A novel approach for solidification enhancement of phase change materials through direct contact with a boiling fluid: An experimental investigation and visualization

Due to their remarkable properties, such as high latent heat and stable temperatures during phase transitions, phase change materials (PCMs) are widely used in thermal energy storage (TES) and thermal management systems (TMSs). However, their low thermal conductivity has limited their broader application across various industries. This study experimentally explores, for the first time, the effects of injecting boiling fluid (BF) into the PCM container as a new method to enhance heat transfer during the solidification process of PCM. To this end, Paraffin wax and acetone with saturation temperature lower than paraffin’s freezing point are selected as PCM and BF, and the influence of four various parameters, namely the initial PCM temperature (75, 85, and 95 °C), the height of the PCM inside the container (15 cm, 25 cm, and 35 cm), the flow rate of the BF (0.32, 0.46, and 0.57 L/min), and the nozzle diameter (2 mm, 3 mm, and 4 mm), on the solidification behavior of PCM, temperature distribution inside the container, and heat transfer enhancement (released energy and Nusselt number) is thoroughly scrutinized. In order to visualize and further evaluate the two simultaneous phase transitions (vaporization of the BF and solidification of the PCM), a Hele-Shaw cell with a height, width, and thickness of 50, 20, and 1 cm is considered as the PCM storage system. The findings indicate that when the BF is injected into the paraffin storage, the high heat transfer coefficient of boiling superbly improves the thermal behavior of PCM, and the solidification process occurs in a much shorter time. Also, boiling of the acetone inside the container and its direct contact with paraffin leads to a significant mixing inside the container and the creation of vortices and turbulent flow in the system, which further improves the freezing phenomenon. Furthermore, it was observed that regardless of other parameters, the flow rate of BF is the most crucial parameter, and after that, the height of the paraffin and the initial temperature have the greatest impact. By employing the highest flow rate, the proposed technique is capable of freezing 0.7, 0.5, and 0.3 L of paraffin in 48, 33, and 18 s, respectively, indicating multiple times of improvement in the full solidification time compared to previous studies.

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.

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.

Parametric study of a scraped surface heat exchanger for latent energy storage for domestic hot water generation

In this work, a parametric study of a Scraped Surface Heat Exchanger (SSHE) for solar Latent Thermal Energy Storage (LTES) has been conducted. The primary challenge in Phase Change Material (PCM) heat exchangers is the formation of a solid layer along the heat transfer surfaces during the latent energy release phase. This reduction in the energy release rate is resolved through the scraping of the solidified PCM, making SSHE systems suitable for domestic hot water generation. Experiments have been performed to evaluate the influence of various operational parameters, including the heat transfer fluid (HTF) mass flow rate, the phase change characteristics of the PCM, the temperature difference between the HTF and the PCM, and the scraping velocity. It has been observed that a HTF Reynolds number (Re) of 100 will require three times more time compared to Re = 600. Moreover, the significance of maintaining a HTF to PCM differential temperature between 20 °C and 25 °C has been experimentally verified to improve the PCM solidification process. Furthermore, the existence of a critical scraping frequency has been demonstrated, beyond which increasing the frequency does not yield to significant improvements in energy extraction. Finally, a correlation has been proposed to predict solidification time as a function of the non-dimensional operational parameters involved, where 95 % of the results fall within an interval of 10 %.

Energy and exergy analysis of a laboratory-scale latent heat thermal energy storage (LTES) using salt-hydrate in a staggered tube arrangement

The energy and exergy analyses were performed for a laboratory-scale latent heat thermal energy storage (LTES) using hexahydrate calcium chloride (CC6) as phase change material (PCM) in a staggered tube array configuration, placed horizontally. The PCM melting and solidification process within the tube array was investigated by performing a numerical analysis using transient two-dimensional Navier-Stokes equations and Realizable k-ɛ turbulence model to predict flow and heat transfer. The enthalpy-porosity technique was applied to model PCM melting and solidification. The accuracy of the numerical model was validated against experimentally obtained data where the numerically predicted and measured air temperature at the tube array outlet and PCM temperatures were compared. Additionally, the pressure drop in the array and the average peripheral heat transfer coefficient calculated from the numerical results were compared to the well-known Zukauskas correlation (Zu). The results show that the melting and solidification process of PCM in the tubes of the array is asymmetric in nature, with the PCM melting taking slightly longer compared to the solidification process. It was also observed that the energy quantity was higher compared to the exergy quantity, as exergy considers entropy generation and accounts for irreversibility within the system.

Effect of ternary hybrid nanoparticles (GO-MgO-TiO2) and radiative heat transfer on the solidification process of PCM inside a triplex tube with hollow fins

Nowadays, due to the features such as high latent heat and constant phase transition temperature, the utilization of phase change materials (PCMs) in energy storage and thermal management systems has attracted scholars' attention. However, the low thermal conductivity and solidification process of these materials has always been a challenge for widespread implementation of them in disparate industries. The current research investigates the characteristics of the PCM solidification process within a triplex tube Latent Heat Thermal Energy Storage System (LHTESS) with innovative hollow fins in the presence of ternary hybrid nanoparticles (THNPs) and radiative heat transfer. The governing equations are solved using Galerkin Finite Element Method (GFEM) with various boundary conditions in the outer wall, such as constant temperature, adiabatic, and coolant fluid temperature (triplex), through FlexPDE software. Furthermore, the effect of key parameters, including shape factor and volume fraction of THNPs, and radiative heat transfer on thermal storage performance is scrutinized. Ultimately, the Taguchi method is adopted to determine the optimal point at which the full solidification time (FST) is lowest. Results show that at 400000 s, the triplex case improved total discharging energy by 23% and 4% in comparison to the constant temperature and the adiabatic case, respectively. Additionally, by including THNPs with a volume percentage of 0.1 and a shape factor of 16.1 instead of 3, the required time for FTS reduces by approximately 13.1% and 21.9%, respectively. Also, the overall solidification times of the PCMs decrease to 36% by enhancing the radiation parameter from 0 to 1. These outcomes illustrate THNPs and considered fins are effective for reducing the FST and the shape factor of THNPs and radiation are key parameters that should be considered by designers.

Performance enhancement of latent heat thermal energy storage system by using spiral fins in phase change material solidification process

Latent heat thermal energy storage systems (LHTESS) have recently gained attention due to the critical demand for clean energy production and storage. The influence of spiral fins on the performance augmentation of a vertical tube-shell LHTESS in the solidification process was studied numerically. Different formation of fins which includes the quadruple, triple, double and single fins were studied. Amount of phase change material (PCM) mass inside the PCM enclosure was preserved equal in all cases and the length of the fins were adjusted for different fin numbers to keep the surface of heat transfer constant to find the optimized fin number. The phase change process was simulated by adopting the enthalpy-porosity technique. It was observed that the triple fin case outperformed other cases and the single fin case showed the least enhancement. When comparing the different cases while the heat transfer surface was kept constant, the triple fin case shows better performance in terms of time averaged Nusselt number and total solidification time respectively. It was revealed that the performance enhancement was not directly proportional with the number of fins and there was a trade-off between fin number and length of each fin.

Structure optimization of tree-shaped fins for improving the thermodynamic performance in latent heat storage

Tree-shaped fins have widely been approved to enhance heat transfer performance in the field of latent heat storage. However, the structure of tree-shaped fins should be optimized to amplify its performance advantages, which are rarely addressed in previous studies. An unsteady numerical model is established to study the thermal performance advantages of tree-shaped fins. A method by coupling a genetic algorithm and a CFD simulation is utilized to optimize the structure of the tree-shaped fins based on the melting and solidification processes of a Phase Change Material (PCM). The results indicate that structural optimization is important and necessary for the application of tree-shaped fins especially in latent heat storage systems. Compared with the radial fins, the optimized tree-shaped fins reduce the phase transition time by 38.83%in the melting process and by 32.71% in the solidification process. Also, the optimized tree-shaped fins increase the average heat transfer rate and average heat transfer coefficient by 65.70% and 65.54% in the melting process while 51.51% and 51.00% respectively in the solidification process. The optimization results also shows that the optimized tree-shaped fins based on different heat transfer processes all show the characteristics of gradually increasing branch length and decreasing branch angle, that is, L0<L1<L2, β1>β2. Interestingly, the optimized structure of the tree-shaped fins based on PCM melting differs from that of the PCM solidification process because of the difference in heat transfer mechanisms. This study provides a method for the structural optimization of tree-shaped fins and increases the application prospect of tree-shaped fins in the field of latent heat storage.

Experimental investigation of air-based active-passive system for cooling application in buildings

• The cooling effect of the interior PCM wall and ceiling was experimentally studied. • The PCM plates provided a cooling effect at constant and transient daily cycles. • Complete solidification of PCM is achieved at an air gap flow rate of 400 m 3 /h. • Complete solidification of PCM is achieved at an inlet temperature of 16°C. • The system is adequate for Mediterranean summer conditions and not for summer heatwaves. Due to the consequences of global warming, cooling of lightweight buildings is one of the main future challenges. The study presents an active-passive system (APS) with phase change material (PCM) plates integrated into the internal wall and ceiling substructure which during the day cools the indoor space passively. During the night, the air gap is ventilated actively to improve the PCM solidification process. The APS was experimentally tested in two identical test cells, PCM modified (cell-A) and reference cell (cell-B). Two different types of scenarios were investigated. First type tested the cooling effect of the PCM during the daytime cycle, determined by the temperature difference between the cell-B and cell-A. The same amount of heat was simultaneously added to both cells which was navigated by the setpoint air temperature in the cell-B (26°C, 30°C, 30°C with background ventilation, 35°C, TRY Ljubljana, TRY Rome and heatwave Ljubljana). Second type tested the PCM solidification time during the nighttime cycle (inlet air temperature ( T ai ) of 15°C, 16°C, and 17°C). The results showed that PCM plates provided the largest cooling effect at in 35°C-scenario. The complete solidification of PCM was achieved at T ai of 16°C. The system is adequate for Mediterranean summer conditions.

Investigations on the thermal performance of a novel thermal energy storage unit for poor solar conditions

A novel thermal energy storage unit (TESU) that can store the heat from lower solar radiation during daytime and preheat air in winter during nighttime for areas with poor solar resources is proposed. To achieve an efficient operation of this TESU for poor solar conditions, this study proposed a structure that innovatively combines tube bundle and spiral tube heat exchangers to enhance heat transfer with paraffin wax as the phase change material (PCM). The thermal performance of the TESU is then evaluated by experimental measurements and a three-dimensional Computational Fluid Dynamics (CFD) model. The numerical modelling provides details of the solidification behavior of the PCM and the two heat transfer processes - thermal heat extracted from PCM and the effective discharging process. Results show that the pure conduction model can suitably describe the solidification process of PCM. The possible maximum amount of heat extraction of 4.68 MJ can be achieved during the discharging process in 20h. Moreover, an air outlet temperature of 11.5 °C is considered the lowest effective temperature. The effective heat extraction efficiency is about 89.74% till the lowest effective temperature is reached.

Investigation on the anti-supercooling effect of sodium polyacrylate as an additive in phase change materials for the applications of latent heat thermal energy storage

Supercooling is an undesirable thermal effect that occurs in most latent thermal storage applications. It reduces the energy performance and generates additional energy consumption in refrigeration systems. We evaluate, as a novel solution to this problem, the potential of combining the Sodium Polyacrylate polymer (SP) with a phase change material (PCM) in order to depress this latter's supercooling degree. Samples of the solutions with different volumes were prepared by adding SP particles to three PCMs at liquid phase: water, ethylene glycol solution at 23%, and NaCl salt solution at 13%. SP-PCM couples present a stable gel structure above the PCM's solidification temperature, which prevents leaks during storage and transport. Differential scanning calorimetry (DSC) and cooling test series were conducted below the PCM solidification temperature in order to measure the thermo-physical properties of the SP-water couple, and to define the effect of the volume sample on the supercooling degree. Experiments show that depending on the sample volume, the SP polymer reduces or even totally eliminates supercooling during the solidification of the PCM, while the latter's physical properties are kept unchanged. Our results suggest that the addition of SP to PCMs helps inducing nucleation and reduces leakage, which leads to a reduction in the energy consumption of the PCM's solidification process for cold thermal storage applications.

Empirical correlations to quantify the effect of metal foam on solidification process in constant thermal capacity and constant volume systems

Abstract Metal foams have been extensively studied to enhance the performance of the Phase Change Materials (PCMs) based Latent Heat Thermal Energy Storage (LHTES) systems. The studies in the literature are primarily focused on analyzing the effect of specific metal foam on the heat transfer augmentation and lacks comprehensive analysis. The present study aims to understand the interdependent effect of thermophysical properties of PCM and metal foam, system geometry, and operating condition on the potential of metal foams to enhance phase-change processes. Besides, the studies are limited to analyze the effect of metal foam addition on phase change processes inside predefined geometries, which fails to consider the reduction in the thermal capacity as the void volume available for the PCM decreases upon the addition of low porosity metal foam. It is crucial to maintain the constant thermal capacity of the LHTES system from both an application and a fundamental analysis perspective. Therefore, in the present study, the dimensions of the LHTES systems are altered to maintain the thermal capacity of the systems, which changes when metal foams are added. Empirical correlations are developed to estimate the effect of embedding metal foam in PCM on the solidification process of PCM in both constant volume and constant thermal capacity systems. These correlations are validated using numerical results, and the differences are limited to within 1% and 1.6% for the solidification time and average heat flux, respectively. The correlations can be extended to unidirectional melting processes with minor modifications, and it reduces reliance on experimental and numerical analysis.

Performance enhancement of PCM latent heat thermal energy storage system utilizing a modified webbed tube heat exchanger

In this study, a novel modified webbed tube heat exchanger was introduced and numerically investigated, to enhance the thermal performance of phase change material (PCM) thermal energy storage (TES) system. To evaluate the thermal performance for this heat exchanger its performance was compared with two types of heat exchanger. These heat exchangers included: the webbed tube heat exchanger and the triple tube heat exchanger. Two-dimensional numerical models were developed. The models enabled us to simulate conduction and natural convection heat transfer mechanisms. The process of solidification (discharging) was monitored during the simulation. The results showed that the PCM solidification process accelerates by 41% when utilizing the modified webbed tube heat exchanger compared to the webbed tube heat exchanger.

Feasibility study on the year-round operation of PCM based free cooling systems in tropical climatic conditions

The free cooling system (FCS) is a conventional system in which the cool energy available in the night ambient air is stored in the phase change material (PCM) and retrieved later during the daytime to reduce the temperature variations in a building. The thermal performance of such passive cooling system predominantly depends on the local climatic conditions. Especially, in tropical countries, where the nighttime ambient temperature for most of the months in a year is high, the complete solidification of PCM through free cooling concept is a challenge. In recent years, several enhancement techniques were introduced to augment the performance of FCS. One such technique is the enhanced free cooling system (EFCS). The EFCS is a hybrid system where the FCS is coupled with a direct evaporative cooling unit to augment the thermal performance of FCS during the PCM solidification process. However, the year-round operational feasibility and the applicability of these cooling systems in tropical climatic conditions are yet to be explored. Considering the above, an assessment study was carried out in the present work with the aim of estimating the monthly average cooling potential of FCS and EFCS under different climatic conditions of a tropical country. The results indicate that cities with temperate and cold climates possess operational feasibility for the FCS throughout the year, whereas for composite/mixed, hot-dry, warm-humid climates, the operational feasibility of the FCS during summer is low and not recommended. On the other hand, results showed that the integration of the evaporative cooling unit with FCS increases the cooling potential and feasibility of year-round operation of the system in all the climate. In addition to the assessment study, the experimental results obtained using FCS and EFCS under real-time ambient conditions of hot-dry, warm-humid and temperate climates are presented. The main aim of the experiments is to study the solidification behavior of the PCM in the above-said climates during the summer and to verify the results of the assessment study.

Investigation of phase change material solidification process in a LHTESS in the presence of fins with variable thickness and hybrid nanoparticles

Present study deals with performance improvement of Latent Heat Thermal Energy Storage Systems (LHTESS) with Phase Change Material (PCM) during the solidification process. The released thermal energy during the solid-liquid phase change is stored in LHTESS. Due to poor thermal conductivity of conventional PCMs, Al2O3-Go hybrid nanoparticles are dispersed into the pure PCM to make Hybrid Nano-Enhanced Phase Change material (HNEPCM). Moreover, fins with variable thickness are applied to expedite the solidification process. In this paper, separate analyzes are investigated for evaluating the effects of adding fins and hybrid nanoparticles. At first, the influence of fin geometric parameters on the solidification acceleration is analyzed, and the best fin configuration is determined using Response Surface Method (RSM) optimization. Then, the influence of dispersing hybrid nanoparticles with different volume fractions into the pure PCM on the solidification rate is reviewed. Also, the outcomes of accelerating the solidification process by using fins and hybrid nanoparticles are compared together. In this study, the unsteady governing equations of the solidification process are solved numerically using standard Galerkin Finite Element Method (FEM). Results depicted that employing optimized fin results in higher solid fraction rate in comparison with dispersing hybrid nanoparticles into the PCM.

Dynamic building envelope with PCM for cooling purposes – Proof of concept

A novel concept based on the dynamic use of phase change materials (PCM) in building envelopes is presented in this paper. The concept aims at breaking the main technical barriers that PCM have been dealing with in its application as passive cooling system: (i) solidification process of PCM is limited and (ii) peak cooling load is delayed but mainly discharged indoors. The concept relies on the ability of the system to modify the position of the PCM layer inside the building envelope with respect to the insulation layer. A proof of concept evaluation based on a numerical tool demonstrates the cooling load reduction potential of this technology when implemented in different construction systems. PCM peak melting temperature as well as the daily activations of the system were optimized using a Particle Swarm Optimization (PSO) algorithm. The numerical results indicate that the dynamic system facilitates dramatically the solidification process of PCM, allowing the system to be designed with lower PCM peak melting temperatures. The potential of the system to charge PCM which solidifies at temperatures lower than indoor set point, allows the technology to be used not only as a thermal barrier but as a cooling supplier system.

Experimental study on discharging performance of vertical multitube shell and tube latent heat thermal energy storage

Abstract An experimental investigation on the thermal performance of vertical multitube shell and tube based latent heat thermal energy storage system (LHTES) during discharging process for solar applications at medium temperature (∼200 °C) is presented in this paper. A commercially available organic phase change material (PCM), A164 having melting temperature of 168.7 °C is stored in the shell side and a thermic oil, Hytherm 600 as heat transfer fluid (HTF), is flown through seven tubes. The effects of three operating parameters, such as inlet HTF temperature, mass flow rate and initial PCM temperature on the outlet HTF temperature are investigated during discharging period. The total energy released, discharging efficiency and heat fraction are analyzed to understand the solidification process of PCM in the multitube LHTES. Thermal Performance Index (TPI) is calculated to evaluate the overall thermal performance of the LHTES under different conditions. The results indicate that the energy released and discharging efficiency increase with increasing mass flow rate and initial PCM temperature and with decreasing inlet HTF temperature. The maximum discharge efficiency and TPI is obtained for the initial PCM temperature of 210 °C with the inlet HTF temperature of 100 °C and the mass flow rate of 0.097 kg/s in this study. Heat fraction is found to be maximum for high mass flow rate, low inlet HTF temperature and higher initial PCM temperature.

Thermo-mechanical analysis of microcapsules containing phase change materials for cold storage

Microencapsulated phase change material slurries (MEPCMSs) offer a potentially efficient and flexible solution for cryogenic-temperature cold storage. In this paper, the phase change material (PCM) microcapsules prepared to form MEPCMSs for cryogenic-temperature cold storage consist of Dowtherm J (DJ) as core material and melamine formaldehyde (MF) as primary shell material. DJ is an aromatic mixture with diethylbenzene as the main component. Composite shell materials are adopted to avoid cracking by adding aluminium oxide (Al2O3) nanoparticles or copper (Cu) coating into/on MF shell. In order to explore the heat transfer behaviour and mechanical stability of the microcapsules during the solidification process of PCM, a thermo-mechanical model is established by taking into account of energy conservation, pressure-dependent solid-liquid equilibria, Lamé’s equations and buckling theory. Based on the proposed model, the effects of shell thickness, shell compositions and microcapsule size are therefore studied on the variations of pressure difference, freezing point, and latent heat. The cause of shell deformation is clearly explained and the shell buckling modes are predicted using the model, which agree well with the experimental observations. The critical core/shell size ratios of avoiding buckling are proposed for the microcapsules with different compositions. Simultaneously incorporation of Al2O3 nanoparticles and Cu coating into/on MF shell can markedly enhance the resistant to buckling. In addition, special attention is paid to cold energy storage capacity of MEPCMSs, which has considerable superiority compared to packed pebble beds.

Numerical Analysis of Phase Change Material Characteristics Used in a Thermal Energy Storage Device

ABSTRACTIn this study, a numerical analysis is performed to investigate the freezing process of phase change materials (PCM) in a predesigned thermal energy storage (TES) device. This TES device is integrated with a milk storage cooling cycle operating under predefined practical conditions. Using this cooling unit, 100 litres of milk is kept cool at 4°C for 48 hours before it is collected. A 2-D model of the TES device is developed in COMSOL Multiphysics to analyze the phase change performance of water-based PCMs. The variations of thermal properties with temperature during the phase change are considered in the analysis. The model is used for exploring the solidification process of PCMs inside the TES device. Temperature variations with time, ice formation, and the impacts of boundary conditions are investigated in detail. Water PCM shows better characteristics in the solidification process in comparison to eutectic PCMs, which is mainly due to the differences between phase change temperatures of the PCMs.