Charging Of Phase Change Material Research Articles

Performance Analysis of Finned-Tube Heat Exchanger Charged with Phase Change Material for Space Cooling

The performance of a latent heat storage unit comprised of phase change material (PCM) enclosed in a finned-tube heat exchanger was evaluated experimentally and theoretically to determine its viability to condition a space during summer. The internal and external design conditions of a typical building were selected and analyzed to determine the type of PCM, and the phase change temperature required for space cooling. Subsequently, a PCM of Plus-ice A17 was selected and charged into a small-scale finned-tube heat exchanger. Extensive measurements were conducted on the PCM heat exchanger at different operating conditions. Meanwhile, a three-dimensional computational fluid dynamics model for the PCM heat exchanger was developed and validated with the experimental measurements and thus simulated. When the airflow velocity increases from 1.3 m/s to 6 m/s, the phase change periods decrease by 25% and 13% for the PCM charging and discharging processes respectively. When the PCM thermal conductivity increases from 1 W/(m·K) to 8 W/(m·K), the phase change periods reduce by 36.3% and 47.7% for the PCM charging and discharging processes respectively. In addition, for the same increased range of PCM thermal conductivity, the charging energy efficiency increases by 16.3%, and the discharging energy ratio drops by 7.1%.

Enhancing the phase change material based shell-tube thermal energy storage units with unique hybrid fins

The poor thermal conductivity of phase change material (PCM) has limited its application to thermal energy storage system. The present work aims to improve the performance of PCM in a vertical shell-tube energy storage unit through unique hybrid fins. The enthalpy-porosity approach is used to numerically investigate the phase change phenomenon. Based on the straight and spiral fin results, the novelty designs of double side spiral fin and hybrid fins, i.e. spiral/straight hybrid fin and straight/spiral hybrid fin, are proposed to further optimize the PCM charging process. The effects of different fin structure, hybrid fin proportion and spiral fin angle on the liquid fraction, temperature and average thermal energy storage rate are discussed. The fin structures can reduce the melting time of PCM up to 100% compared to the no-fin case. Although double side spiral fin outperforms the straight fin for the PCM melting behavior, the hybrid fin configurations shows the best enhancement, especially for the straight/spiral hybrid fin. The optimal fin design for the straight/spiral hybrid fin case is that with 0.7 fin proportion and 180° spiral angle, with up to 11.8% reduction of the melting time compared to the designs of other fin proportions and spiral angles. This work demonstrates the potential of this unique hybrid fin to be integrated with PCM for efficient thermal energy storage.

Modeling and analysis of PCM‐encapsulated solar thermal energy storage system for space heating

AbstractIn this study, a phase change material (PCM)‐encapsulated packed‐bed thermal energy storage (PB‐TES) system is intended for Day‐round space heating in the winter. Solar concentric collectors act for day‐time heating and TES charging, while the stored energy can be used at night and intermediate time for space heating. A region‐wise techno‐economic analysis of PCM candidates is made to compare the costs and sizes of solar collectors and PB‐TES. A spherical capsule filled with sodium nitrite (NaNO2) and sodium nitrate (NaNO3) is numerically investigated during the PCM charging at constant thermal input. After complete liquefication, the charging time for NaNO2 and NaNO3 capsules is 3280 and 4300 s, respectively, holding the maximum stored energy of 733.4 KJ/kg at 285°C and 687.27 kJ/kg at 310.12°C, respectively. In addition, the stored exergy is obtained 238.78 and 234.74 kJ/kg for NaNO2 and NaNO3, respectively; however, the average exergetic effectiveness for NaNO2 and NaNO3 are 0.54 and 0.46. Despite the lower energy storage capacity (kJ/kg) of NaNO3, the PB‐TES volume is less with NaNO3 than with NaNO2 due to higher density. However, the average cost ($/tonne) of NaNO3 PCM is 50% higher than NaNO2. Subsequently, the thermal efficiency of the proposed system is estimated at 27.68% and 26.94% during day and night‐time operations.

Simulation for charging of phase change material in existence of nanomaterial within solar energy storage system

Regarding possible solutions for thermal management of the storage unit, probably the main remedy might be to equip the system with an extended surface made from metallic materials which have high conductivity. In this study, by changing the number (n) and thickness (t1) of plates, four arrangements of the system have been suggested and solid matrix were made of three materials namely: Silicon Carbide (SiC), Aluminum (Al) and Stainless Steel (SS). Moreover, the heat absorption of phase change material (PCM) has been improved with loading of alumina nanoparticles. Increasing the number of radial plates and decreasing their thickness makes the heating penetration to increase. When the structure of geometry for SiC plates changes from (n = 5, t1 = 4 mm) to (n = 40, t1 = 0.5 mm), the melting time declines around 63.87 %. With changing the material from SS to SiC, the period of melting decreases about 66.33 % when n = 5, t1 = 4 mm. The worst case among scrutinized cases in view of speed of melting happens when n = 5, t1 = 4 mm involving Al. The best case occurs when n = 40, t1 = 0.5 mm involving SiC material and its melting time is 87.84 % lower than that of the worst case.

Dynamic Investigation of a Coupled Parabolic Trough Collector–Phase Change Material Tank for Solar Cooling Process in Arid Climates

The use of solar energy for cooling processes is advantageous for reducing the energy consumption of conventional air-conditioning systems and protecting the environment. In the present work, a solar-powered cooling system with parabolic trough collectors (PTC) and a phase change material (PCM) tank is numerically investigated in the arid climates of Saudi Arabia. The system contains a 160-kW double-effect absorption chiller powered by solar-heated pressurized water as a heat transfer fluid (HTF) and a shell and tube PCM as a thermal battery. The novelty of this paper is to investigate the feasibility and the potential of using a PTC solar field coupled to a PCM tank for cooling purposes in arid climates. The numerical method is adopted in this work, and a dynamic model is developed based on the lumped approach; it is validated using data from the literature. The functioning of the coupled system is investigated in both sunshine hours (charging period) and off-sunshine hours (discharging period). The PTC area in this work varies from 200 m2 to 260 m2 and the cooling capacity of the chiller ranges from 120 kW to 200 kW. Obtained results showed that the 160-kW chiller is fully driven by the 240 m2-solar PTC during the charging period and about 23% of solar thermal energy is stored in the PCM tank. It was demonstrated that increasing the PTC area from 220 m2 to 260 m2 leads to a reduction in the PCM charging time by up to 45%. In addition, it was found that an increase in the cooling loads from 120 kW to 200 kW induces a decrease in the stored thermal energy in the PCM tank from 450 kWh to 45 kWh. During the discharging period, the PCM tank can continue the cooling process with a stable delivered cooling power of 160 kW and an HTF temperature between 118 °C and 150 °C. The PCM tank used in the studied absorption chiller leads to a reduction of up to 30% in cooling energy consumption during off-sunshine hours.

Finned coil-type energy storage unit using composite inorganic hydrated salt for efficient air source heat pumps

The imbalance between the variable power load during day and night and the energy supply of office building heating can supplement a staggering electricity economy. In this study, a novel composite inorganic hydrated salt phase change material (PCM) was fabricated with a melting temperature of 50.3 °C using CH3COONa·3H2O (the primary material), KNO3 (the eutectic material), Na2HPO4·12H2O (the nucleating agent), and carboxymethyl cellulose (CMC, the thickener) in a mass ratio of 89 %:8 %:1.5 %:1.5 %. Moreover, we developed a modular finned coil-type energy storage unit (ESU) with a PCM charging capacity of 1200 kg and a theoretical heat storage capacity of 315 MJ. Subsequently, we created an ESU test system for an air source heat pump (ASHP) operated at the valley electricity period from 23:00 to 7:00. The heat storage, heat release, and defrosting functions were tested, and the operational cost of heating for the office building was evaluated. The results reveal that the composite PCM exhibited stable thermal properties, but more accurate working medium flow matching is required to improve the heat transfer tail phenomenon. Furthermore, the ASHP-ESU reduces the defrosting time by 63 % and improves the efficiency by 6–9 % compared to conventional ASHP. The operating costs are the lowest at 4.66 CNY/month/m2 with valley electricity operation compared with the other three heating modes. Therefore, the ASHP-ESU system for office building heating in off-peak operation is an economical and sustainable approach for the power system.

Effect of Asymmetric Fins on Thermal Performance of Phase Change Material-Based Thermal Energy Storage Unit.

Phase change material (PCM)-based thermal energy storage units (TESU) have very low thermal conductivity that compromise their charging and discharging rate. The present study focuses on an enhancement in charging rate as well as an increase in the uniformity of the melting rate. A rectangular cavity consisting of two horizontal partial fins is studied. The horizontal partial fins are placed symmetrically in a PCM-based TESU. In the current work, the melting rate of PCM was enhanced using asymmetric arrangement while keeping all other parameters the same, thus showing the positive effect of asymmetric configuration in such storage systems. The position and the pitch of each fin is optimized to improve heat transfer characteristics of the TESU. The numerical investigation of the problem is performed. TESU with asymmetrically placed fins show better performance in terms of higher charging rate as well as uniformity of the charging rate. The asymmetric placement of the fins suggested by present study increased the charging rate by 74.3% on average as compared to the symmetrically placed fins in the storage system. The charging rate uniformity is improved by 43.7%. The asymmetric fin's placement conserved the convection strength for a longer melting duration and so increased the Nusselt number by 80.2% as compared to the symmetrically placed fins. Thus, it can be concluded that the performance of asymmetric fins is better in the charging of PCMs than the symmetrically placed fins in a PCM-based TESU.

Numerical simulation study of the effect of mechanical vibration on heat transfer in a six-fin latent heat thermal energy storage unit

The optimization of heat transfer in latent heat thermal energy storage units (LHTES) has received a lot of research during the past decade, and the use of fins to enhance heat transfer in phase change materials (PCM) is one of the efficient ways. However, the existing studies do not consider the influence of mechanical vibration which widely exists in LHTES. To fill the research gap in this important topic, a horizontal shell-and-tube six-fin latent heat thermal energy storage unit is investigated in this study, and the effects of mechanical vibration are investigated by numerically simulating the PCM charging process in LHTES using the Enthalpy-porosity technique. In this paper, the charging rate of PCM, variation of key parameters such as Nusselt number, temperature and liquid fraction are analyzed in detail under vibration conditions. And the following conclusions can be obtained. (1) Mechanical vibration can significantly increase the charging rate of PCM, under the condition of vibration amplitude of 10mm and frequency of 1Hz (the melting time of PCM is reduced by 46.6%). (2) The enhancement effect of mechanical vibration on the melting rate of PCM increases with the increase of amplitude and frequency, but the enhancement efficiency keeps decreasing. These observations result from that the mechanical vibration changes the velocity of the liquid PCM, so the forced convective heat transfer of the PCM is significantly enhanced. Furthermore, the melting process of PCM is sensitively affected by increasing the amplitude than by increasing the frequency. Increasing the amplitude or frequency alone (amplitude from 10mm to 40mm; frequency from 1Hz to 4Hz) can reduce the total melting time of PCM by 75% and 68.7%, respectively.

Model-based predictive control of multi-stage air-source heat pumps integrated with phase change material-embedded ceilings

This paper presents a model-based predictive control strategy to optimize the operations of phase change material (PCM) ceiling panels coupled with a multi-stage air-source heat pump. A three-stage prototype heat pump unit has been built and tested in the laboratory, with the low and medium stages designed for space heating/cooling and the high compression stage dedicated to charging of the PCM energy storage. To facilitate optimal control of the integrated heat pump system, a mixed-integer linear programming formulation is derived through linearization of the heat pump model and a mixed-integer reformulation of the PCM dynamic governing equations. A predictive control strategy is synthesized based on the resultant control formulation and implemented in a receding horizon scheme that optimizes the PCM charging and the zone temperature schedules simultaneously to leverage both the passive (associated with building construction materials) and active (PCM) storage capacities of a building. The control strategy has been tested along with three benchmarking control scenarios using a co-simulation platform for a prototypical detached house in Atlanta, GA. Test results showed that application of the proposed control strategy to the PCM-integrated heat pump could provide 27.1% electricity cost savings while a fine tuned rule-based control strategy could achieve cost savings of 20.4%, compared to a baseline case without PCM storage, under a time-of-use rate tariff.

Numerical thermal performance analysis of a PCM-to-air and liquid heat exchanger implementing latent heat thermal energy storage

Due to the mismatches in energy supply and demand in thermal systems, employing latent heat thermal energy storage using phase change materials (PCMs) is a reliable and effective solution. In this regard, this paper introduces an innovative PCM-to-air and liquid heat exchanger to increase thermal system performance by providing a hybrid heat source to the airside. A novel numerical work based on multiphysics coupling of heat transfer and double fluid flow and phase change within a complex geometry is represented. Numerical heat transfer analysis is performed on the model based on three-dimensional computational fluid dynamics simulation. In order to make a thorough thermal performance assessment, the dynamic behaviour of the system is investigated for both PCM charging and discharging processes. Furthermore, the effect of airside flow variation on the thermal response of the system is studied, and the results are discussed based on fluids temperature, heat transfer rate, and the PCM phase transition procedure. It is demonstrated that the PCM can store excess heat from the working fluid during the charging process and releases it to the airside during the discharging process. The heating load of 323 kJ is stored during the charging process which has enabled the PCM to provide up to 6 min of extra airside heating time during discharging. The share of PCM latent component of the airside heat transfer is determined to be around 48 %. It is also observed that by increasing the airflow rate, the discharged heat load is decreased slightly, and the heating time is reduced notably. The presented thermal energy storage system offers a unique solution for the start-stop function implemented in many hybrid and electric vehicles. During short periods of engine shutdown, the system could provide passenger thermal comfort and enable effective energy savings.

Boosting the air conditioning unit performance using phase change material: Impact of system configuration

Boosting the energy efficiency of air conditioning (AC) systems will considerably impact on lowering domestic power consumption. Innovative methods are being developed to enhance AC performance. One promising method involves integrating phase change materials (PCM) with the AC systems. The significant PCM charging period is a primary limitation of coupling AC systems with PCM in the previous research. The current study aims to investigate the impact of coupling an AC unit with various PCM container configurations (e.g., parallel plates, staggered and aligned tubes, and elliptical tubes) on PCM charging and discharging, and AC performance. During the nighttime, the low ambient temperature is charged inside the PCMs. Then, during the daytime, the hot ambient air is cooled by passing through the cold PCM heat exchanger before passing over the unit condenser. A complete dynamic mathematical model for the proposed system is constructed and solved numerically using ANSYS software. Results indicate that applying the cylindrical arrangement lowers the solidification time of the PCM at night by approximately one-third compared to the plate arrangement. Also, raising the inflow air temperature of the air-PCM heat exchanger increases the air temperature difference through the heat exchanger and saving percentage of the AC's power and decreases the PCM's charging and discharging time. For inflow air temperatures of 318.15 K, 313.15 K, and 308.15 K, the maximum average percentage of saved power is around 25 %, 18.7 %, and 12.5 %, respectively for 2 h working and around 8.4 %, 7.2 %, and 6.3 %, respectively for 8 h working of the AC unit. Cylindrical configuration is preferable for daily use of AC systems as the charging process can be achieved through the nighttime.

Analysis-Based Key Components Selection of Latent Heat Thermal Energy Storage System Along With Active Heat Transfer Enhancement

Abstract Energy storage is an effective approach to bridging the gap between energy supply and demand created due to the sporadic nature of solar energy. Thermal performance enhancement is a key research subject for effective energy storage using latent heat thermal energy storage (LHTES) systems. This paper focuses on the analysis-based design of suitable LHTES system components for solar absorption-based cooling applications with a working temperature of up to 200 °C. Initially, the medium-temperature range (80 °C to 200 °C) phase change material (PCM) is selected using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). Further, a suitable heat transfer fluid (HTF) is selected along with the design of a geometrical assessment and an appropriate LHTES system. Finally, the effect of the stirrer on the thermal performance of the LHTES system has been discussed. The melting time of PCM reduces by 58% while input energy increases by 20 kJ with an increase in HTF inlet temperature from 180 °C to 190 °C. However, input energy increases faster with a further increase in HTF inlet temperature while melt time does not reduce significantly. Therefore, selecting optimum HTF inlet temperature is an important criterion for efficient LHTES system design. Implanting a rotating stirrer at 200 RPM inside a PCM tube decreases the net-input energy by 73 kJ. Using back-of-the-envelope calculations, the analysis-based selection of key components of the LHTES system will pave the way forward to designing an application-specific LHTES system. Further, this study can be instrumental in theoretically scrutinizing the stirring effect on PCM charging before experimental analysis.

Impact of inclination on the thermal performance of shell and tube latent heat storage system under simultaneous charging and discharging: Numerical investigation

In this paper, the impact of inclination on the thermal performance of latent heat storage system (LHSS) based cylindrical shell and tube heat exchanger is investigated. During the simultaneous charging and discharging (SCD) process, a visualized numerical simulation is carried out to demonstrate the melting process of phase change material (PCM). The SCD technique for the LHSS comprises charging of PCM from one side while discharging from the other. To investigate the performance of the LHSS, a transient numerical model based on the enthalpy-porosity method is used. The distribution of temperature, melt fraction, energy stored, and average Nusselt number are analyzed to study the effect of natural convection on the performance of LHSS with inclination angles viz. 90° (vertical) 60°, 30° and 0° (horizontal). Results illustrate that better thermal performance is provided by the horizontal (0°) configuration. The effect of natural convection on the PCM under the SCD melting process has differed with the angle of inclination. The position of cold heat transfer fluid (HTF) showed a considerable influence on the process of melting. With the decrease of inclination angle from 90° to 0°; there is an increase in melt fraction by 38.02 %. The maximum energy stored (231 kJ) obtained at the horizontal (0°) configuration is 26.2 % higher than the vertical position. Also, the steady-state condition is observed earlier in the horizontal position. Further, the flow behavior of PCM with inclination is also illustrated.

Economic cost and technical efficiency analysis of thermal management of a triple pack of lithium-ion battery with forced airflow and nano-phase change materials

In this paper, the thermal management (THMA) of a lithium-ion battery pack (BPA) and economic analysis of the cost of cooling electricity consumption are studied numerically. The BPA contains 23 cylindrical batteries in such a way phase change material (PCM) surrounds the batteries. Finally, 7 different models are employed by changing the angle of the vanes from 0 to 5° in the period of 0–25 min and BPA temperature, as well as the amount of molten PCM and outlet temperature, are studied. Economic analysis is done for three European countries at 5 Reynolds numbers. The use of guide vanes with an angle of 1° creates the lowest maximum temperature (TM) and the average temperature (TAV) of the BPA, especially at times above 15 min. The airflow guide vanes with angles of 1 and 4° causing the lowest and highest air temperatures at the outlet in more than 20 min. Also, the vanes with an angle of 1° create the maximum amount of solid PCM. Economic studies also show that the lowest and highest power consumption for PCM charging occurs at the Reynolds numbers of 300 and 500, respectively.

Simulation of charging of PCM within a duct containing nanoparticles

AbstractWith the involvement of sinusoidal containers of phase change material (PCM) inside the duct, new configuration for the ventilation system has been achieved in the current paper. Mixture of TiO2 and RT25 was assumed as PCM, and the temperature of domain is fixed at 25°C at the start of the process. Owing to the radiation of the sun, air becomes warmer up to 35°C and with entering the air into the domain with Re = 6000, the melting process starts. The cold air at the outlet section can be utilized for ventilating the room. Homogeneous model for NEPCM and K‐ɛ approach for turbulent air flow has been incorporated. ANSYS FLUENT was applied for simulating this unsteady mechanism, and verification of the model was done according to previous experimental work. To control the air gap among tanks, the factor “b” was utilized and the influence of the fraction of titanium oxide (ϕ) was analyzed in results. As nano‐sized material has been added, more heat can be received to RT25 and the completed process can be reached in lower time. With considering the highest “b,” as nano‐sized material, the required time reduces from 20,672 to 19705 s. When ϕ = 0, growth of b leads to a reduction of time of about 42.57%.

Thermal characteristics of hydrated salt blended with Tio2 for thermal energy storage

AbstractDevelopment leads to an increment in the demand for energy. Conventional sources of energy are fulfilling our energy demands but they are crossing environmental barriers resulting in adverse climatic change. Renewable source of energy is becoming popular as a solution to the energy crisis. To reduce the gap between energy demand and supply, energy storage methods should be developed more. In this paper, performance improvement of phase change material for energy storage purposes has been investigated. NaNO3/KNO3, which is a salt hydrate, is used as a phase change material. The weight proportion of NaNO3 and KNO3 is 55% and 45%, respectively. TiO2 is used as an additive for performance improvement of phase change material in nanoparticle form with different particle sizes of 10, 20, and 30 nm. All the abovementioned nanoparticles were blended with phase change material (PCM) to make three different samples for testing. The weight percentage of TiO2 is constant in every sample, which is 5%. Specific heat, thermal conductivity, charging, and discharging of PCM have been measured for different particle sizes along with the effects of temperature variation on the abovementioned properties. Specific heat has shown an increment by 16%, 20.5%, and 23.6%, and thermal conductivity has shown a decrement by 13%, 16.5%, and 21.5% for 10, 20, and 30 nm particle sizes, respectively. Blending with TiO2 has increased the rate of heating and decreased the rate of cooling of phase change material.

Benefits of integrating phase-change material with solar chimney and earth-to-air heat exchanger system for passive ventilation and cooling in summer

A solar chimney (SC) integrated with an earth–air heat exchanger (EAHE) produces a new passive system (SCEAHE) that can passively provide fresh air and cooling capacity. An inherent disadvantage of the coupled system is the mismatch of solar radiation, airflow, and internal load. To mitigate this issue and further improve the indoor thermal environment, a phase-change material (PCM)-based SCEAHE system is proposed and investigated using a validated numerical model. The thermal inertia of the SCEAHE system was improved by integrating PCM. The simulated results showed that the maximum absorber surface temperature of the SCEAHE system with PCM was 78.8 °C, 16.2% lower than without PCM. The PCM charging and discharging periods were approximately 9.5 h (05:30–15:00) and 14.5 h, respectively. The completely melted period lasted approximately 5 h (15:30–20:30); solidified PCM appeared from 02:00 to 7:15 with a maximum of 24% at 05:30. By integrating PCM, the SCEAHE airflow rate was increased by 50% at night, and the maximum airflow rate was reduced by 17.8% to 209.5 m3/h during the day. The EAHE outlet air temperatures varied between 24.8 and 26.5 °C, and between 24.4 and 27.2 °C for the SCEAHE with and without PCM, respectively. With the reduced outlet air temperature, the daily indoor air temperature for the SCEAHE with PCM varied between 25.1 and 28.4 °C; the maximum indoor air temperature was reduced by 0.8 °C compared with a SCEAHE without PCM, suggesting that including PCM in the SCEAHE system increases the useful cooling capacity and creates more stable indoor thermal comfort.

Experimental and numerical analysis of thermal performance of shape stabilized PCM in a solar thermal collector

A typical solar domestic water heating system suffers from low energy efficiency due to multiple heat transfer process among components, i.e., the solar thermal collector and the thermal energy storage. In this work, a compact design of storage-integrated solar thermal collector and its compatible phase change material (PCM) storage material were explored. The salt hydrate based composite PCM, the sodium acetate trihydrate (SAT), was used to create a shape stabilized PCM (ssPCMs) for a feasible PCM by its low leakage and high thermal conductivity. The developed ssPCMs has been tested experimentally and a numerical model has been developed to obtain the effective thermal property of the developed ssPCMs by comparing the predicted results with the measurements. Furthermore, the model has been used to study the (dis)charging behavior of PCM in a storage-integrated solar thermal collector which is composed of an evacuated tube and a double spiral coils heat exchanger. A geometrical optimization has been performed to achieve 2.6 times longer of discharging period with a minimum outlet temperature of 55 °C. Moreover, the circulating water is found useful in increasing the PCM charging rate with 9% by transferring the heat from the surface to the center of tube.

Phase Change Process inside Toroidal Tube Heat Exchanger with Internal Fins

Inadequate melting of phase change material (PCM) in concentric tube and shell and tube heat exchangers appeal motivations for innovative latent heat thermal energy storage (LHTES) systems. In the current research, a novel application of toroidal tubes inside the LHTES system for charging of PCM is presented. The proposed heat exchanger geometry is numerically investigated with the help of enthalpy – porosity approach. Toroidal tubes are assumed to be filled with PCM (i.e., coconut oil) and fabricated inside cylinder accommodating the heat transfer fluid (HTF). To establish and accelerate homogenous melting, flat thin fins are attached inside the toroidal tubes, and transient simulations are performed. The system performance is investigated for variations of (i) fin numbers (Nf), (ii) fin length (L0), and (iii) fin orientations (Fo) in terms of (i) melt fraction (MF), (ii) average PCM temperature, (iii) energy stored by PCM, and (iv) Nusselt number (Nu). Simulation results indicate that fin orientation stands out as the dominant factor for heat transfer enhancement compared to fin numbers and fin length. In the toroidal tube LHTES system, it is found that even though fin numbers and fin length are identical, correctly oriented fins (i.e., case 8) can provide 50.52% more rate of energy storage than a system with random fin orientation (i.e., case 5). Moreover, the optimum fin orientation (i.e., case 8) can (i) save 65.28% time for 100% melting and (ii) provide 168% more rate of energy storage than a system without fins. Based on the melting progression pattern, the current study encourages the use of multiple PCMs having dissimilar melting point temperatures with fins.

Latent heat storage system by using phase change materials and their application

Due to the rapid exploitation of fossil fuels, energy sources are becoming nonrenewable, and there is a need to develop other technologies to provide a clean supply of energy. The heat is stored in the thermal storage unit utilizing phase change materials in one of two ways: sensible heat or latent heat. When the temperature of phase change materials rises, energy stored in the perceptible form in the materials rises as well. While latent heat is stored during phase change of materials during the charging process and retrieved during phase change discharging at a virtually constant temperature during the discharging process. Latent heat has a large capacity to store a large amount of thermal energy per unit space. The use of phase change material (PCM) can be found in a variety of fields, including:•Improving the efficiency of photovoltaic cell.•Thermal storage of solar energy.•Waste heat recovery.•Engine cooling.•Building cooling to store energy during peak time and retrieving during requirement.The main drawback of PCM is its low thermal conductivity, which can be increased by incorporating fins and adding nanoparticles (to enhance heat transfer) in PCM. Our task in this study was to evaluate literature and develop applications for PCM, as well as to reduce PCM charging and discharging by boosting the rate of heat transfer.