Behavior Of Phase Change Materials Research Articles

Melting and Solidification Characteristics of PCM in Oscillated Bundled-Tube Thermal Energy Storage System

Phase change material (PCM) based thermal energy storage (TES) is an important solution to the waste of heat and intermittency of new energy sources. However, the thermal conductivity of most PCMs is low, which severely affects the thermal energy storage performance. Oscillation of the tube bundles in a TES unit can intensify the convection of liquid PCM and, therefore, enhance heat transfer. However, the energy storage performance of bundled-tube TES systems in response to oscillation at different amplitudes and frequencies has not been well understood yet, and the optimum time to apply the oscillation during phase transition remains unexplored. To address this issue, this present study was carried out. First, the melting behaviour of PCM with oscillation starting at different times was investigated. Then, the influences of oscillation frequency and amplitude on the melting performance were explored. Finally, the solidification behaviour of PCM with oscillation starting at different times was examined. Results show that the oscillation can accelerate the phase transition process by enhancing convective heat transfer. Compared to the case without oscillation, the complete melting and solidification times are reduced by 8.2 and 6.7% for the case with oscillation starting at 200 s, respectively. The effect of oscillation frequency on the melting enhancement is negligible, while the oscillation amplitude has an important effect on the melting enhancement.

Porous carbon network-based composite phase change materials with heat storage capacity and thermal management functions

Porous carbon network-based phase change composites have been widely used in energy storage and thermal management related fields. At present, the demand of energy crisis for photothermal energy storage and the prevention and management of thermal abuse of electronic equipment constantly promote the development of carbon-based composite phase change materials (PCMs). Therefore, a series of new composite materials filled with PCMs and polyethylene glycol (PEG) and added with flame-retardant magnesium hydroxide were developed, which makes the composites show certain flame-retardant ability in high-temperature environments. The results show that the thermal conductivity increases from 0.25 to 0.94 W/m·K, and the latent heat of phase change remains at 142.7 J/g. In addition, due to the capillary effect caused by the synergistic effect of multi-pore carbon (MPC) structure and cellulose macromolecular chain, the composite material has good shape stability, which effectively prevents the leakage behavior of PCMs during solid-liquid phase change. Moreover, the absorbance of the composite material can reach 1.28 L/(g cm) in the ultraviolet–visible light range of 200 nm–800 nm, and its photothermal conversion efficiency can reach 90.8 %. Therefore, this material has a broad application prospect in the thermal management of electronic equipment and photothermal energy storage devices.

Expression of Concern: Investigating the Thermal Behavior of Phase Change Materials of Ethylene Glycol-Filled SiO2 Plates in the Presence of Solar Radiation by Molecular Dynamics Simulation

Expression of Concern: Investigating the Thermal Behavior of Phase Change Materials of Ethylene Glycol-Filled SiO2 Plates in the Presence of Solar Radiation by Molecular Dynamics Simulation

Investigation of the effect of model structure type on the thermal performance of phase change materials through molecular dynamics simulation

Using molecular dynamics (MD) simulation, the thermal efficacy of phase change materials (PCMs) in solar energy applications and solar thermal energy storage was evaluated. In order to achieve this objective, an investigation was conducted into the structure's temperature (Temp), velocity, and density profiles, heat flux, thermal conductivity, charge and discharge time, and thermal stability. Three models of tube, shell, and shell-tube were adopted to scrutinize the atomic behavior and thermal performance (TP) of PCMs. The results show that the maximum density of the tube model, shell model, and shell-tube model was 0.042, 0.036, and 0.033 atom/A3, respectively. Other numerical results showed that the maximum velocity for the three structures of tube model, shell model, and shell-tube model under the initial Temp of 300 K was 0.0066 Å/fs, 0.0059 Å/fs, and 0.0054 Å/fs, respectively. The structure in the tube model manifested more optimal atomic behavior compared to other models. The TP of simulated structures revealed that the heat flux of the samples reached 5.69, 4.85, and 4.15 W/m2, respectively. Finally, the thermal conductivity of the structures approached 1.35, 1.32, and 1.31 W/m.K, respectively. The results suggested that the tube model had the most thermal stability and showed the optimal thermal behavior in the simulation. The findings of this study, particularly the optimal atomic behavior and thermal stability of the tube model, can be useful in designing and optimizing PCMs for solar energy applications. In general, this research had the potential to significantly advance the field of solar energy system efficiency and cost-effectiveness.

Numerical study of the melting rate enhancement of nano phase change material in a modified shell and tube heat exchanger

The current investigation employs numerical analysis using ANSYS Fluent software to explore the melting behaviour of phase change material (PCM) and nano-PCM in a semi-circular shell and tube heat exchanger, utilizing dual side heating for enhanced conduction and convection rates of heat transfer. The study incorporates aluminium oxide nanoparticles at volume concentrations of 2 %, 4 % and 6 % within paraffin wax and assessing their impact on melting and thermal energy storage rates. Notably, the 2 % nanoparticle volume concentration exhibits an enhanced storage rate as compared to higher concentrations. The increase in nanoparticle concentration from 0 % to 2 %, 2 % to 4 % and 4 % to 6 % results in percentage reduction in melting time of 21 %, 3.51 % and 2.8 % respectively. Semi-circular configuration shows significant improvement in the energy storage rate as compared to the circular triplex tube configuration. The maximum energy storage rate of PCM for the semi-circular and circular configurations is 1.15 kW and 1.04 kW respectively, marking a 9.56 % increase over the circular configuration. Moreover, the semi-circular and circular configurations using nano-PCM achieve a maximum energy storage rate of 1.19 kW and 1.14 kW, representing a 4.20 % increase over the circular configuration.

Study of melting behavior of phase change material in a square enclosure with constant and variable heat flux at different wall heating conditions: A numerical approach

Latent heat thermal energy storage system offers the most promising cost-effective solution in thermal energy storage applications like solar water heaters to building air conditioning, textile industries, pharmaceutical industries, etc. In this article, the melting process of phase change material (PCM) in a square enclosure with constant, linearly increasing, linearly decreasing and sinusoidal heat flux on different sides of the wall is studied. The result shows that double-wall heating has the highest melting rate followed by side-wall heating and bottom-wall heating. This happens because double-wall heating increases the heat transfer area. Between side-wall heating and bottom-wall heating with uniform heat flux, side-wall heating gives a higher melting rate due to the higher length of solid–liquid interface promoting the heat transfer to solid PCM, thus increasing the melting rate. Again, for different heat distributions of side-wall heating the linearly decreasing heat flux provides the highest melting rate. This type of heat distribution actually transfers more heat to the lower part of the container, which counters the effect of convection, resulting in an enhanced melting process. On the other hand, in the case of distributions at bottom-wall heating, linearly increasing heat flux shows the highest melting rate. In addition, for linearly increasing heat flux, the shape of the liquid cavity is triangular, which gives more space and thereby intense natural convective circulation. This enhanced convection heat transfer leads to a higher melting rate.

Investigating the Impact of Cell Inclination on Phase Change Material Melting in Square Cells: A Numerical Study.

In order to determine the ideal degree of inclination that should be employed for constructing effective thermal energy storage systems, it is important to examine the impact of inclination angle on the melting behavior of phase change materials (PCMs) such as paraffin wax within a square cell. In consequence, this would guarantee the greatest capacity for energy release and storage. Additionally, analyzing this influence aids engineers in creating systems that enhance heat flow from external sources to the PCM and vice versa. To find out how the cell's inclination angle affects the melting of PCM of paraffin wax (RT42) inside a square cell, a numerical analysis is carried out using the ANSYS/FLUENT 16 software. Specifically, the temperature and velocity distributions, together with the evolution of the melting process, will be shown for various inclination angles, and a thorough comparison will be made to assess the influence of inclination angle on the PCM melting process and its completion. The findings demonstrated that when the cell's inclination angle increased from 0° to 15° and from 0° to 30° and 45°, respectively, the amount of time required to finish the melting process increased by 15%, 42%, and 71%, respectively. Additionally, after 210 min of operation, the PCM's maximum temperature is 351.5 K with a 0° angle of inclination (horizontal) against 332.5 K with an angle of inclination of 45°.

A Pore Scale Study on Heat Transfer Characteristics of Integrated Thermal Protection Structures with Phase Change Material

Phase change material (PCM) are characterized by their high latent heat and low density. Combining PCM with building walls, aircraft fuselages, and other structures can significantly enhance the thermal sink capability of these structures. In order to address the issue of low heat storage efficiency resulting from the low thermal conductivity of PCM, a novel integrated thermal protection structure (ITPS) architecture with a supportive structure based on a porous lattice has been designed. Experimental and numerical methods were employed to investigate the thermal response characteristics of the ITPS with and without PCM, the melting behavior of PCM within the porous lattice, and the effects of lattice configuration and pore size on the PCM melting rate. The current ITPS study includes evaluation of two types of lattice configurations and three different pore sizes. The results indicate that the inclusion of PCM reduces the internal panel temperature of the ITPS by approximately 15%. The melting of PCM occurs primarily at the central region of the porous lattice and gradually spreads towards the periphery until complete melting is achieved. Specifically, the Gibson–Ashby lattice configuration enhances the PCM melting rate by 43.5%, while the tetradecahedron lattice configuration yields a 53.1% improvement. Furthermore, for PCM with different pore sizes, smaller pores exhibit faster melting rates during the early and intermediate stages, whereas larger pores exhibit faster melting rates in the later stages as the proportion of liquid PCM increases. The conclusions of this study provide valuable insights for the application of PCM in the field of thermal management.

A numerical study on the effects of inclination angle and container material on thermal energy storage by phase change material in a thick-walled disc

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

Thermal performance of phase change materials with anisotropic carbon fiber inserts

In thermal energy storage systems, phase change materials (PCMs) are widely used for thermal energy management. Most PCMs have low thermal conductivities, which limits the heat transfer rate within PCM and thus makes the phase-changing process very slow. However, thermal conductivities of PCMs can be altered by inserting targeted additives. We hypothesize that the size and shape of these additive inserts play a key role in thermal management efficiency. To this end, the impacts of carbon fiber (CF) inserts on the phase change behavior and consequent heat transfer efficiencies of inorganic and organic PCMs were investigated using experiments and simulations. Long, anisotropic CFs with high thermal conductivities formed continuous fast heat flux tunnels inside PCMs to enhance the heat transfer. Such CFs could extend the phase change fronts from the limited container-shaped interface to the larger surface of numerous CF inserts inside the PCM. These special CF inserts work with a new heat transfer mechanism, different from conventional small additives or long isotropic CF inserts. The thermal energy release rate increased by 2.5 times with 1 wt.% anisotropic CF inserts in inorganic PCM. However, CF inserts in liquid organic PCM hindered the natural convection and compromised the improved heat conduction. The lab-scale multiphysics simulations support these experimental observations and indicate that CF inserts have potential to enhance heat transfer in inorganic PCMs, but they are less effective in organic PCMs.

Thermal properties of novel phase change materials based on protic ionic liquids containing ethanolamines and stearic acid for efficient thermal energy storage.

In the field of energy harvesting, phase change materials (PCMs) hold great promise. 2-hydroxyethylammonium stearate ([HEA]Ste), bis(2-hydroxyethyl)ammonium stearate ([DHEA]Ste), and tris(2-hydroxyethyl)ammonium stearate ([THEA]Ste) ionic liquids (ILs) demonstrate promising capabilities to enhance thermal energy storage (TES) performance within the 30-100 °C temperature range. This research presents these ILs as PCMs for the first time, emphasizing their environmentally friendly characteristics, safety profile, and cost-effectiveness. The chemical composition and microstructure of these PCMs were investigated using scanning electron microscopy (SEM), and fourier transform infrared spectroscopy (FT-IR), while differential scanning calorimetry (DSC) was employed to assess their latent heat of fusion and specific heat capacity. Furthermore, thermal gravimetric analysis (TGA) was utilized to evaluate the thermal stability of these ILs. In addition, valuable insights into the surface properties and behavior of PCMs at the nanoscale are provided using atomic force microscopy (AFM). Results show that the latent heats of fusion for [HEA]Ste, [DHEA]Ste, and [THEA]Ste are about 171.12, 152.58, and 136.55 kJ kg-1, respectively. Also, thermal stability analysis shows the maximum stability (99.5%) for [HEA]Ste. Ultimately, a custom-built setup featuring a cell containing a PCM derived from synthesized ILs and a commercially available thermoelectric generator (TEG) was employed to measure live voltage (V) in the conversion of heat energy into electrical power. On the other hand, specifically in this measurement we recorded the output voltage (open circuit case) of the TEG device versus time and demonstrated that after turning off the thermal energy source, the proposed system provides the electrical energy for a while (more than 2 hours).

A comparative study of twisted and straight fins in enhancing the melting and solidifying rates of PCM in horizontal double-tube heat exchangers

This study explores the melting and solidifying behaviour of phase change materials (PCM) in horizontal double-tube heat exchangers equipped with straight and twisted fins. Three-dimensional numerical simulations employing the enthalpy-porosity approach were conducted. RT35, which acts as the PCM, was enclosed in the inner tube, while water circulated as the heat transfer fluid (HTF) in the outer tube. The impacts of fin configuration (twisted versus straight), number of pitches, thickness, and length on the heat storage and recovery rates were analyzed during the melting and solidifying modes. The results demonstrated enhanced heat transport and phase change rates by incorporating fins, with twisted fins outperforming straight fins. Specifically, the charging and discharging rates improved by approximately 10% and 14% with twisted fins compared to straight fins, and by 15% and 40% relative to the finless case, respectively. The heat transfer rates showed direct correlations with the number of pitches, thickness, and length of the twisted fins. The twisted fins generated a swirling PCM flow, reducing thermal resistance. The study provides important guidelines on optimising twisted fin parameters like length, thickness, and orientation to improve the performance of thermal storage systems across renewable energy, waste heat recovery, and related applications.

Wet Impregnation Method for Synthesis of Phase Change Composite of N-Octadecane in Porous Silica Gel

Thermal energy storage is gaining more interest as people aim to utilization of solar energy. The thermal energy can be stored in the form of latent heat and used for building applications that require increasing energy. This report investigated the wet impregnation method for the synthesis of thermal storage material, namely phase change composite (PCC) for two purposes: to create a simple method for the synthesis of PCC and study behaviors of phase change material (PCM) when confined inside the pore. Particularly, the PCC was synthesized using n-octadecane and silica as PCM and porous matrix, respectively. The characterization of the product was conducted by various analytical methods: N2 adsorption/desorption isotherm, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). Results showed that the n-octadecane was successfully impregnated into a silica porous network through simple steps of the wet impregnation method. The porosity analysis confirmed the confining of PCM inside matrix pores. The n-octadecane was easily kept inside pores by the capillary and surface tension forces.  without any chemical interaction. At maximum impregnation, n-octadecane accounted for 70% of the composite. This sample presented a shape-stability at up to 90 oC, provided a latent heat of 145 J g-1, and was selected as optimal PCC.

Effect of different micelles on charging and discharging behavior of phase change material

Phase change material (PCM) offers high-density thermal energy storage, making it attractive for thermal management applications of electronic circuitry and thermal energy storage. However, PCM, like paraffin wax, ideal for such low-temperature applications, has very low thermal conductivity. The present study focused on the improvement of the thermal conductivity of paraffin wax using surfactants. The surfactants used as thermal conductivity enhancers (TCE) are cetyltrimethyl ammonium bromide (CTAB), Dioctyl sodium sulfosuccinate (known as AOT) and sodium dodecyl sulfate (SDS). The surfactant self-aggregation called a micelle, acts as conducting medium inside the paraffin wax, providing better thermal conductivity. The highest heat transfer rate with a peak temperature of 71 °C was observed in the case of AOT micelle paraffin wax. Adding SDS, CTAB, and AOT surfactants increased the highest temperatures by 4%, 8.4%, and 18.33% compared to pure PCM.

Numerical simulation and ANN prediction of phase change material embedded within 3D printing lattice structures

This study investigates the phase change material (PCM) embedded within different lattice structures, including SC, BCC and FCC, at various porosities. The examination focuses on understanding the thermal behaviour and heat transfer characteristics during the melting and solidification processes. Key parameters analysed include the maximum temperature of the heater, PCM melting and solidification, and Nusselt number. The results indicate that the maximum temperature of the heater decreases with increasing porosity. The Nusselt numbers for the different lattice structures exhibit similarities, with the SC lattice showing a slightly higher Nusselt number. Melting and solidification times increase with increasing porosity. An artificial neural network trained by the Bayesian Regularization algorithm is used to predict three key parameters. The porosity and time are set as input parameters of the network. The optimal structure of the ANN show high accuracy in estimating the performance of PCM with three lattice structures. The minimum mean square error and the maximum correlation coefficient are 0.00003601 and 0.9998, respectively. The trained ANN is employed to predict the behaviour of PCM with 82 % SC, BCC and FCC. A perfect agreement is observed between ANN predictions and the simulation for PCM with lattice structures featuring 82 % porosity.

Investigating temperature change rate and pore confinement effect on thermal properties of phase change materials for de-icing and low-temperature applications in cementitious composites

Incorporation techniques of phase change materials (PCM) in cementitious composites have a significant influence on thermal properties. This study investigated the thermal behavior of low-temperature PCM when subjected to varying temperature change rates and pore confinement inside the porous network of lightweight aggregates (LWA) and encapsulation using melamine-formaldehyde-based polymer. Three categories of thermal energy storage (TES) specimens were prepared: (i) Bulk PCM (i.e., liquid PCM), (ii) micro-encapsulated PCM (MPCM), and (iii) four different LWAs infused with PCM (PCM-LWA). The thermal properties of small-scale individual TES specimens were analyzed using a low-temperature differential scanning calorimeter (LT-DSC) to evaluate the effect of ramp rates. Dynamic vapor sorption (DVS) analysis was utilized to characterize the pore structure of LWAs. LT-DSC results show that undercooling of the PCM significantly increases with the rise in ramp rate for all the specimens; temperature change rate affects the nucleation and crystallization growth process during the phase transition. Pore structure characterization of LWAs indicates that the majority of the pores (> 92 %) were larger than 17.3 nm (i.e., macropores). Confined liquid properties are subjected to modification due to interaction with the confining surfaces, as explained by Gibbs-Thomson theory. PCM incorporated in the LWA porous network experienced variable degree of supercooling during phase transition; magnitude of confinement pressure is dependent on the pore diameter, structure, and tortuosity. Experimental evidence suggested that PCM-LWA will exhibit gradual expulsion of enthalpy of fusion over a larger temperature range (i.e., ∼−5 °C to 4.28 °C) in comparison to MPCM (i.e., ∼4.28 °C).

Numerical study of combined phase change material and water cooling in hybrid wavy microchannels for HCPV cell

HCPV cells are known for their high efficiency in converting sunlight into electricity. However, this increased efficiency also generates higher levels of heat, posing a risk of cell damage. Therefore, the study proposes the combination of a phase change material (CPCM) and liquid flow in hybrid wavy microchannels to ensure stable temperature within the high-concentration photovoltaic (HCPV) cells. A three-dimensional numerical model has been developed to capture the thermal behavior of PCM integrated with water cooling in a microchannel heat sink. The comparison and analysis involved contrasting cases with phase change material (PCM) and cases without PCM. The PCM cases were studied at Reynolds number (Re) 100, while the cases without PCM were investigated at Reynolds numbers of 100 and 200. Three distinct types of PCM were employed, specifically OM 32, Rt 35, and PA - SA/EG. The various microchannel geometries under consideration included Raccoon, wavy, and hybrid wavy microchannels. The results showed that using both PCM and water cooling in a microchannel is preferable over using only water cooling. The outcomes reveal that employing PCM 3 (CPCM) in conjunction with the raccoon wavy microchannel design, there is an 11.61% reduction in the maximum pressure drop, along with a decrease of 6.58% in the maximum solid substrate temperature. Moreover, this configuration attains the highest electrical efficiency, reaching 39.32%.

Assessment of the performance of metaheuristic methods used for the inverse identification of effective heat capacity of phase change materials

Phase change materials (PCMs) are one of the promising technologies for the carbon neutral future, since they can be effectively used for thermal energy storage (TES), and therefore can mitigate the energy supply/demand mismatch characteristic for renewable energy resources. Mathematical models describing thermal behaviour of PCMs require various material properties, such as specific heat capacity, thermal conductivity or density, which are in many cases difficult to obtain experimentally. This paper introduces an inverse identification procedure which utilises heuristic optimisation methods to solve the inverse problem. The air-PCM heat exchanger was considered as a studied device. In order to avoid any uncertainties tied to the experimental measurement, the exact solution was generated by the numerical model directly (referred to as “pre-simulated” scenario). The cost function was constructed as a root mean square difference between the given calculated and pre-simulated outlet air temperatures. In total seven different case studies (five with a base model and two with an extended model) were investigated for the inverse identification of the effective heat capacity of a PCM and seven different heuristic optimisation methods were utilised for each case study. The results have shown that the LSHADE and DE methods were the best performing ones and that one method outperformed the other depending on the problem settings.

Thermo-kinetic behaviour of green synthesized nanomaterial enhanced organic phase change material: Model fitting approach

Metal, carbon and conducting polymer nanoparticles are blended with organic phase change materials (PCMs) to enhance the thermal conductivity, heat storage ability, thermal stability and optical property. However, the existing nanoparticle are expensive and need to be handle with high caution during operation as well during disposal owing to its toxicity. Subsequently handling of solid waste and the disposal of organic PCM after longevity usage are of utmost concern and are less exposed. Henceforth, the current research presents a new dimension of exploration by green synthesized nanoparticles from a thorny shrub of an invasive weed named Prosopis Juliflora (PJ) which is a agro based solid waste. Subsequently, the research is indented to decide the concentration of green synthesized nanoparticle for effective heat transfer rate of organic PCM (Tm = 35–40 °C & Hm = 145 J/g). Furthermore, an in-depth understanding on the kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM after usage via Coats and Redfern technique is exhibited. Engaging a two-step method, we fuse the green synthesized nanomaterial with PCM to obtain nanocomposite PCM. On experimental evaluation, thermal conductivity of the developed nanocomposite (PCM + PJ) increases by 63.8% (0.282 W/m⋅K to 0.462 W/m⋅K) with 0.8 wt% green synthesized nanomaterial owing to the uniform distribution of nanoparticle within PCM matrix thereby contributing to bridging thermal networks. Subsequently, PCM and PCM + PJ nanocomposites are tested using thermogravimetric analyzer at different heating rates (05 °C/min; 10 °C/min; 15 °C/min & 20 °C/min) to analyze the decomposition kinetic reaction. The kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM and its nanocomposite of PCM + PJ provides insight on thermal parameters to be considered on large scale operation and to understand the complex nature of the chemical reactions. Adopting thirteen different chemical mechanism model under Coats and Redfern method we determine the reaction mechanism; kinetic parameter like activation energy (Ea) & pre-exponential factor (A) and thermodynamic parameter like change in enthalpy (ΔH), change in Gibbs free energy (ΔG) and change in entropy (ΔS). Dispersion of PJ nanomaterial with PCM reduces Ea from 370.82 kJ/mol−1 to 342.54 kJ/mol−1 (7.7% reduction), as the developed nanomaterial is enriched in carbon element and exhibits a catalytic effect for breakdown reaction. Corresponding, value of ΔG for PCM and PCM + PJ sample within heating rates of 05–20 °C/min varies between 168.95 and 41.611 kJ/mol−1. The current research will unbolt new works with focus on exploring the pyrolysis behaviour of phase change materials and its nanocomposite used for energy storage applications. This work also provides insights on the disposal of PCM which is an organic solid waste. The thermo-kinetic profile will help to investigate and predict the optimum heating rate and temperature range for conversion of micro-scale pyrolysis to commercial scale process.

Numerical study on latent heat storage systems with and without fins during simultaneous charging and discharging process

A numerical study is carried out on phase change material (PCM) impregnated in shell and tube heat exchangers with and without fins. The simultaneous charging and discharging (SCD) process is considered for the study, where the heat transfer occurs between heat transfer fluids (HTFs) and PCM simultaneously. The study intends to analyze the heat transport behavior of PCM and energy transport between the hot and cold HTFs. In the SCD process, the hot HTF is circulated through the hot tube, whereas cold HTF is made to simultaneously pass through the cold tube. The influence of the latent heat storage system (LHSS) inclination on the thermodynamic behavior of PCM with and without fins is inspected. To evaluate the effect of orientation four angles are considered. The angles include 90°, 60°, 30° and 0°. The investigation shows that the orientation significantly influences convective strength and melt fraction. An increase in melt fraction by 13.1% and 39.35% is observed when orientation is changed from 90° to 0° in finned and unfinned LHSS. It is also observed that the LHSS with fins gave an 18.31% higher melt fraction than without fins for vertical configuration. The LHSS with fins gave uniform temperatures and higher average Nusselt numbers. Among various configurations considered, LHSS with fins can be considered for 90° (vertical) and 60° orientations. In contrast, the LHSS without fins can be preferred for 30° and 0° (horizontal) positions.