Phase Change Material Heat Research Articles

An energy saving strategy on the composite phase change material and spiral liquid cooling channel for battery thermal management

In order to ensure the safety and stability of the cooling system during the operation of the battery thermal management system combined with composite phase change material cooling and liquid cooling, it is usually necessary to continuously pump cooling water. It inevitably caused that the latent heat of composite phase change material could not be fully released and extra pump power was consumed. In the study, five different energy saving strategies were proposed and the energy efficiency ratio was defined to evaluate their cooling effects and energy saving. The effect of energy saving strategies on energy consumption of liquid cooling and latent heat utilization of composite phase change material was analyzed. The results show that III and V can meet their cooling requirements and have a high energy efficiency ratio. The screw pitch and cooling water flow rate in these two modes were investigated. The results show that the increase in screw pitch reduces the heat transfer efficiency, resulting in an increase in Tmax and ΔTmax, and ΔTmax exceeding the maximum range. Diminishing the cooling water flow will precipitate a rise in battery temperature, enabling the CPCM to operate at its maximum capacity and consequently decreasing ΔTmax. As a cooling water flow of 20 ml/min in III and V all can satisfy the cooling requirements. Additionally, the III was also competent when the cooling water temperature was raised from 25 °C to 35 °C.

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 %.

CFD Analysis of a Latent Thermal Storage System (PCM) for Integration with an Air-Water Heat Pump

Heat pumps driven by sustainable electricity sources have been identified as a technology that can contribute to reduce carbon dioxide emissions. Furthermore, a heat pump can also provide energy savings when combined with a thermal energy storage system. Heat pumps can optimize their efficiency by accumulating thermal energy during periods of lower electricity demand, resulting in shorter operational durations and decreased overall energy consumption. In this work, the combination of a latent heat storage system with an air-water heat pump has been numerically analysed and experimentally tested. A phase change material (PCM) heat exchanger with an immersed plate was designed using a 3D CFD model (COMSOL Multiphysics®). The heat exchanger configuration with six steel plates immersed in the phase change material tank was proposed to enhance heat transfer in the storage system. The developed model is validated against experimental data from a real case study, demonstrating a maximum error of approximately 3% during the discharging phase. Additionally, the study explores the effects of different inlet heat transfer fluid temperatures and flow rates on the PCM solidification time.

Numerical investigation of heat transfer in wire and tube-based phase change material heat exchanger

The utilization of latent heat storage units with their high energy density and isothermal heat transfer behavior can enhance the performance of thermal energy systems. This study aims to investigate the effect of fin placement on the melting time of a wire and tube-based Phase Change Material (PCM) heat exchanger using numerical simulations. The study introduces a new complex geometry for the heat exchanger, and numerical analysis of heat transfer was conducted in Ansys Fluent software using an established solidification and melting model. The numerical results were validated against experimental data, and it was found that the position of the tubes and fins had a significant impact on heat transfer within the PCM. The model was able to predict temperature data with a maximum discrepancy of 3%.

Experimental study on the thermal protection enhancement of novel phase change material integrated structural firefighting gloves under high-heat exposures

Phase change material (PCM) has been widely studied for efficient thermal management. This work is the first holistic experimental research on the temperature control performance of PCM-integrated firefighters' gloves. The results showed that the thermal protection time could be extended by 2-5 times in the direct contact to hot object tests and around 1.5 times under the radiant/convective heat source tests when embedding a 1-mm-thick PCM layer in gloves. The PCM of melting point 68 °C showed the best thermal protection performance in all test conditions since it had the most efficient phase change function during the heating process. Considering the PCM location effect, the PCM with lower melting point (68 °C) showed better performance when located close to external environment (heat source) and the PCM with higher melting point (108 °C and 151 °C) showed better performance when located close to hand. The optimum PCM thickness would be in the range of 0.5-1.0 mm for both thermal protection improvement and hand dexterity purposes. In addition, the time for continuous temperature rises on the hand surface at post-heat exposure was longer when embedding PCM in firefighters’ gloves due to the stored latent heat in PCM.

Effect of PCM-filled hallow fin heat sink for cooling of electronic components — a numerical approach for thermal management perspective

This paper aims at the PCM-based heat sink for electronic cooling. In the present analysis, paraffin wax-based phase change material (PCM), in 3-fin and 4-fin hollow heat sinks with the proper volume of PCM in the temperature of the electronic components can be controlled. The PCM-filled heat sinks are placed on top of the high heat-generating integrated circuit (IC) components. The aim is to reduce the maximum temperature of the electronic components and keep them below their critical temperature, hence increasing the life of the IC chips. A correlation is put forward for dimensionless temperature ([Formula: see text]) in terms of heat flux ([Formula: see text]), volume content ([Formula: see text]) and size of the IC chips ([Formula: see text]). It has been found that there will be a 4–[Formula: see text]C drop in temperature when compared to solid fins heat sinks. It is confirmed that the temperature of the IC chip is a strong function of heat flux, size and volume content of PCM.

Multistage Porous Carbon Derived from Enzyme-Treated Waste Walnut Green Husk and Polyethylene Glycol for Phase Change Energy Storage.

The thermal storage performance, cost, and stability of phase-change materials (PCMs) are critical factors influencing their application in the field of thermal energy storage. Porous carbon, with its excellent support, thermal conductivity, and energy storage properties, is considered one of the most promising support matrix materials. However, the simple and efficient synthesis of high-performance and highly active bio-based materials under mild conditions still faces challenges. In our work, a novel method for preparing new functional composite phase-change materials based on enzyme treatment technology and using waste walnut green husk biomass and polyethylene glycol as raw materials was developed. The enzymatic treatment method exposes the internal structure of the walnut green husk, followed by the adjustment of the calcination temperature to increase the adsorption sites of the biochar, thereby stabilizing polyethylene glycol (PEG). The porous properties of walnut green husk biochar effectively regulate the phase-change behavior of polyethylene glycol. In the biochar carbonized at 600 °C, the PEG loading reached 72.09%, and the absorption heat of the solid-solid phase-change material (SSPCM) reached 194.76 J g-1. This work not only enriches the application of biomass in heat storage but also demonstrates the broad prospects of SSPCMs in solar thermal utilization.

The confinement effect on phase change materials by physicochemical structure of wood-based materials

The impact of the three-dimensional graded porous structure and active functional groups of wood on phase change materials (PCM) is worthy of consideration. It often results in a decrease in the actual latent heat (A) of wood-based composite phase change materials (WCPCM) compared to the theoretical latent heat (T). In this study, natural balsa wood was initially chosen as the encapsulation carrier for paraffin wax (PW) and polyethylene glycol (PEG) to explore the impact of interface effects on PCM. The results demonstrate that the A/T ratio of WCPCM prepared with balsa wood and PW is 0.99, which is higher than that of WCPCM prepared with balsa wood and PEG (0.96) due to the interface confinement effects caused by hydrogen bonding. Subsequently, delignified balsa wood (LW) and hemicellulose-removal balsa wood (HW) were utilized to encapsulate PW, and the spatial confinement effects on PCM were discussed. Delignification resulted in the opening of pits. While hemicellulose removal resulted in the generation of more mesoporous structures in wood. This resulted in a specific surface area of 19.204 m2/g, which is 142.2% larger than that of LW. Both of these changes improved the permeability of balsa wood, leading to an encapsulation efficiency of 88.1% (LW) and 89.6% (HW) for PW, respectively. However, due to the spatial confinement effects of nanoscale pores, the A/T value of HW/PW (HWP) is lower (0.93) than that of PW encapsulated with LW (0.96), ultimately resulting in a lower latent heat for HWP (172.8 J/g) compared to LWP (174.8 J/g). This study provides theoretical insights into selecting PCMs and encapsulation matrices in future research.

Spatiotemporal Utilization of Latent Heat in Erythritol‐based Phase Change Materials as Solar Thermal Fuels

AbstractSolar thermal fuels (STFs) have been particularly concerned as sustainable future energy due to their impressive ability to store solar energy in chemical bonds and controllably release thermal energy. However, currently studied STFs mainly focus on molecule‐based materials with high photochemical activity, toxicity, and compromised features, which greatly restricts their applications in practical scenarios of solar energy utilization. Herein, we present a novel erythritol‐based composite phase change material (PCM) as a new type of STFs with an outstanding capability to store solar energy as latent heat in its stable supercooling state and release thermal energy as needed. This composite PCM with stored thermal energy can be maintained stably at room temperature and subsequently release latent heat as high as 224.9 J/g during the crystallization process triggered by thermal stimuli. Remarkably, solar energy can be converted into latent heat stored in the composite PCM over months. Through mechanical stimulations, the released latent heat can increase the temperature of the composite up to 91 °C. This work presents a new concept of using spatiotemporal storage and release of latent heat in PCMs for solar energy utilization, making it a potential candidate as STFs for developing future clean energy techniques.

Spatiotemporal Utilization of Latent Heat in Erythritol-based Phase Change Materials as Solar Thermal Fuels.

Solar thermal fuels (STFs) have been particularly concerned as sustainable future energy due to their impressive ability to store solar energy in chemical bonds and controllably release thermal energy. However, currently studied STFs mainly focus on molecule-based materials with high photochemical activity, toxicity, and compromised features, which greatly restricts their applications in practical scenarios of solar energy utilization. Herein, we present a novel erythritol-based composite phase change material (PCM) as a new type of STFs with an outstanding capability to store solar energy as latent heat in its stable supercooling state and release thermal energy as needed. This composite PCM with stored thermal energy can be maintained stably at room temperature and subsequently release latent heat as high as 224.9 J/g during the crystallization process triggered by thermal stimuli. Remarkably, solar energy can be converted into latent heat stored in the composite PCM over months. Through mechanical stimulations, the released latent heat can increase the temperature of the composite up to 91 °C. This work presents a new concept of using spatiotemporal storage and release of latent heat in PCMs for solar energy utilization, making it a potential candidate as STFs for developing future clean energy techniques.

Experimental study on a rectangular evaporator loop heat pipe with a phase-change material heat sink

To satisfy the heat dissipation requirements of high heat flux electronic devices in extreme conditions where no suitable heat sink exists, such as in the flight process of hypersonic aircraft and the re-entry process of spacecraft, a rectangular evaporator loop heat pipe (LHP) with a phase-change material heat sink was designed and developed. Extensive experimental studies on the thermal control performance of the LHP have been performed, mainly including the startup performance, maximum temperature control time, dynamic response to varying heat load, and the heat transfer limit. Experimental results showed that the LHP could successfully realize the startup at a small heat load as low as 5 W. Under 100 W heat load, the LHP can keep operating for 4 h and 16 min at most with the operating temperature lower than 50 °C, including 2 h and 40 min of quasi-stable operation. The heat transfer limit of the LHP could reach up to 200 W, corresponding to a heat flux of 13.3 W/cm2 at the evaporator. In addition, the LHP exhibited excellent dynamic response characteristics to varying heat loads, holding great application potential in future thermal control tasks in extreme conditions.

High latent heat phase change materials composites based on MXene/biomass-derived cellulose nanocrystalline aerogel for solar-thermal energy conversion and storage

In this study, novel tetradecylamine/MXene/cellulose nanocrystal composite phase change materials (TDA/MXene/CNC CPCMs) were prepared using a vacuum impregnation method. For the first time, lightweight MXene/CNC composite aerogel was employed as a support material in energy storage, with TDA serving as the phase change material. The latent heat of TDA/MXene/CNC CPCMs reached 221.5 J/g. Furthermore, the density of the MXene/CNC-2 composite aerogel was 0.0614 g/cm3, and its loading rate for TDA was as high as 90.6 wt%. Additionally, the thermal conductivity of TDA/MXene/CNC CPCM-5 was 0.491 W/(m·K), 1.87 times higher than that of pure TDA. The TDA/MXene/CNC CPCMs exhibited exceptional thermal stability up to 120 °C and maintained excellent shape stability at 60 °C. The composites exhibit a superior solar-thermal conversion ability with the conversion efficiency as high as 94.1%, The incorporation of MXene significantly enhances the photothermal conversion capability, providing an important avenue for the high-efficiency utilisation of solar energy.

Thermal management of honeycomb heat sink filled with phase change material for smart lighting applications

Recently, thermal management of LEDs lamps has become increasingly essential due to the widespread integration of LEDs in smart lighting applications. In this work, we focus on the thermal analysis of convective heat transfer using a honeycomb heat sink designed for LEDs lamp cooling. Three different heat sink geometries were examined: an aluminum-filled honeycomb radiator, a hollow honeycomb radiator, and a hollow honeycomb radiator incorporating a phase change material (PCM) layer. The results obtained from numerical simulations using COMSOL Multiphysics® showed that the third heat sink geometry, when employed in short-duration lighting applications, led to a 25% reduction in temperature for a 20W power lamp. We also determined the optimal operational time, during which the temperature drop is maximum. Moreover, we observed that the integration of a PCM-filled honeycomb radiator in cyclic lighting applications (involving on/off cycles and high/low power settings) significantly mitigates temperature rise in the lamp by leveraging the PCM's heat storage capacity. This approach effectively prevents thermal shocks, ensures prolonged LEDs performance, and contributes to energy savings in the lighting sector. By addressing the thermal management challenges associated with LEDs lamps through innovative heat sink designs and the utilization of PCM, our research offers valuable insights for enhancing the overall performance and efficiency of LED lighting systems.

Experimental study on a loop thermosyphon with microencapsulated phase change material suspension

Microencapsulated phase change material suspension (MPCMS) represents an innovative category of functional thermal fluids. This novel working fluid not only preserves the substantial energy density and high latent heat of phase change materials (PCM), but also mitigates the issues related to PCM, including susceptibility to aggregation and low thermal conductivity. This article selects phase change microcapsules with a phase change temperature of 70 °C, and uses pure water as the base liquid to prepare MPCMS as the working fluid for the loop thermosyphon. A series of heat transfer experiments are conducted, and the results are compared with those of pure water experiments. A 135mm*650mm copper loop thermosyphon, is designed and constructed to investigate the effect of various input power on the heat transfer performance. The results show that the addition of MPCMS can reduce the wall temperature by up to 2.9°C and the loop thermal resistance by 6.3%. Compared with water, the loop thermosyphon with MPCMS has better start-up characteristics. The performance of the MPCMS is affected by various parameters, which are interconnected. Particles in close proximity to the wall display erratic movement, fluctuating across different temperature zones, thereby undergoing a continuous cycle of melting and solidification. This study establishes a basis for further investigation into the practical implementation of MPCMS in industries.

Experimental study of phase change material heat sinks coupled with Cantor fractal fins for thermal management of photovoltaic systems

Phase change materials (PCMs) have recently been proven to be a very efficient method for temperature control of photovoltaic (PV) panels, but their performance is still constrained by the low thermal conductivity of PCMs. A kind of Cantor fin inspired by fractal theory has been proposed to enhance the thermal management performance of PCMs for PV panels. A constant heat flux boundary was employed in a plexiglass-based PV-PCM system to simulate a solar irradiation scenario. The impact of fin types, namely Cantor fractal fins and rectangular fins, on the thermal management performances of the PV-PCM system was investigated under different geometric constraints, including equal surface area and equal volume conditions. The results indicated that the employment of fins alleviated the temperature stratification phenomenon of the PCM. Meanwhile, the fins reduced the melting time by up to 14.9 % and improved the thermal performance of the PV panel with a maximum temperature drop of 13.1 °C. Compared with rectangular fins, the Cantor fractal fins with three odd segments could exhibit a faster melting time and a higher performance in achieving temperature homogeneity across the PV panel under the surface area constraint. Additionally, under the volume constraint, the Cantor fractal fins could raise the temperature uniformity of the PCM and PV panel, and yield a larger electrical efficiency than their counterpart at certain time ranges.

Revolutionizing solar water distillation: maximizing efficiency with pyramid solar stills enhanced by fins, evacuated tubes, nanomaterial, and phase change materials—a comprehensive review

Abstract The availability of water and energy is crucial for human survival, yet rising industrialization and population growth have escalated demand, particularly in developing economies. Despite efforts to address water scarcity, contamination persists, leading to widespread diseases. Conventional purification methods like reverse osmosis are effective but expensive and energy-intensive while boiling exacerbates air pollution. In this context, solar still systems present a promising solution, harnessing abundant sunlight to distill seawater into drinkable water. By integrating phase change material (PCM) and sensible heat storage, these systems can enhance efficiency and reduce energy consumption. This article explores the optimization of solar still systems through the selection of suitable PCM and sensible heat storage materials. The primary objectives are to improve distillation efficiency and heat recovery, making the process more eco-friendly and cost-effective. By addressing water scarcity and energy consumption simultaneously, these optimized systems offer a sustainable approach to water production, particularly in regions with ample sunlight. Through a comprehensive review, this research aims to advance the understanding of solar still technology and facilitate its widespread adoption, ultimately contributing to global efforts toward water security and environmental sustainability.

An Experimental Study on the Influence Solution Concentration and Nano-Additives on Cold Storage Performance of Tetrabutylammonium Bromide

Tetrabutylammonium bromide (TBAB) is considered a promising alternative cold energy storage material. Due to the high dissociation heat of phase transition at an atmospheric pressure of 278–293 K, which reaches 200–500 kJ/kg, this substance is considered an effective cold energy storage medium for air conditioning systems. In this paper, the cold storage crystallization process of TBAB solution with different concentrations was tested by conducting experiments and the phase transition’s temperature and latent heat were measured. Finally, the growth characteristics of TBAB hydrate crystals with different concentrations (10%, 20%, 30% and 40%) were analyzed. Considering the cold storage temperature, phase transformation temperature and latent heat, the cold storage effect is the best when 40% TBAB solution is used. Although single substance phase change materials have a long service life, they have problems with low thermal conductivity and high undercooling. Therefore, researchers usually improve the performance of phase change materials by adding other auxiliary materials, thereby enhancing their application prospects. Among these auxiliary materials, adding nano additives to phase change materials can significantly improve latent heat, thermal conductivity and nucleation ability, while also reducing undercooling. Therefore, we studied the influence of different nano-additives (Al2O3, SiC, TiO2 and ZnO) on phase change materials. The composites with excellent properties were screened by cooling step cooling curve and differential scanning calorimeter (DSC). Compared with pure TBAB solution, the phase transition latent heat of the composite phase change materials (PCMs) prepared by adding nanoparticles were significantly increased. The results show that adding nano-SiC into 40% TBAB solution can obtain better performance. This work not only provides reference for the further research, but also a sight to design the phase change materials for the application of new phase change cold storage materials.

The optimum fin length distribution of tabular PCM heat exchanger

AbstractThe study aims to find the optimal fin length distribution for improved heat transfer during melting and solidification in a tubular phase change material (PCM) heat exchanger (HE) designed for heat storage. Three types of horizontal PCM tabular HEs, all with five longitudinal fins, were studied numerically. While maintaining a constant heat‐transfer area, each model depicts a unique fin length distribution design. The first model, which serves as the reference design, has a uniform fin length distribution and each fi\n is 30 mm long. The second model has shorter upper and side fins and longer lower fins. The third model has long lower fins but shorter than that of the second model, with short side fins and no change in upper fin length with reference design. The findings indicate that the second model exhibits the best heat‐transfer performance for the melting process, while the first model is most effective for solidification. Interestingly, the third design emerges as the optimum choice for both melting and solidification processes, where for 1 h of melting operation, results obtained 87%, 92%, and 90% for three models, respectively, from the first uniform model to the third model. While for 2 h of solidification the result obtained 11%, 17%, and 13% liquid fraction for the three models, respectively.

A numerical study on control mechanism of heat transfer in a double pipe PCM heat exchanger by changing eccentricity

The thermal analysis of a double pipe phase change material heat exchanger is studied numerically. The study is done for three cases as; a) Case A: a melting process when inner pipe is maintained at a constant temperature higher than melting point, b) Case B: a solidification process when the inner pipe temperature is constant but less than melting temperature, and c) Case C: for a cyclic thermal storage when the inner pipe surface temperature periodically changes between temperatures of Cases A and B. The aim of this study is to find the optimum position of the inner pipe for each studied cases and to investigate the differences in heat transfer mechanism of the above cases for various Rayleigh numbers. The obtained results show that for Case A, the best position of the inner pipe depends on Rayleigh number, but the bottom region provides the shortest melting time for Ra>105. For the Cases B and C, the center must be preferred for all Reynolds numbers since the conduction heat transfer controls the process. In spite of many reported studies in literature, it is better to study on the enhancement of heat transfer for solidification rather than melting process.

Experimental and numerical study on the model of hybrid fiber phase change concrete frozen shaft wall.

In this study, phase change materials (PCMs) were innovatively incorporated into hybrid fiber concrete. The properties of PCMs, which absorb and release heat during phase transitions, enable the concrete to actively respond to complex and varying temperature environments. This integration reduces the internal temperature differentials within the concrete, thereby preventing temperature-induced cracks in deep wellbore structures. Through the temperature control model test of the frozen shaft wall, it can be seen that the hybrid fiber phase change concrete (HFPCC) significantly reduces the internal temperature difference, and the maximum temperature difference along the radial direction is 35.84% lower than that of benchmark concrete (BC). The numerical simulation results indicate that a moderate phase transition temperature should be selected in engineering. The phase change temperature should not be close to the ambient temperature and peak temperature. The peak temperature can be reduced by 9.32% and the maximum radial temperature difference can be reduced by 30.89% by selecting an appropriate phase change temperature. The peak temperature and radial maximum temperature difference are both proportional to the latent heat of phase change. The temperature control performance of phase change concrete can be further improved by increasing the latent heat of phase change materials.