Phase Change Material Thickness Research Articles

Thermodynamic modeling and performance analysis of photovoltaic-thermal collectors integrated with phase change materials: Comprehensive energy and exergy analysis

Phase change materials (PCMs) integrated with photovoltaic-thermal (PVT) collectors can simultaneously generate and store electrical and thermal energy. However, design optimization requires accurate modeling of the complex heat transfer processes in PCMs under varying operating conditions. This study introduces an efficient simulation approach with generalized Nusselt number correlations to enable precise and rapid analysis of PCM thermal performance. A numerical model is developed to quantify heat fluxes, node temperatures, energy and exergy outputs across PCM solid, melting, and liquid states. Extensive analysis is conducted to explore the impact of irradiation, ambient temperature, PCM thickness, tilt angle, and wind speed on PVT performance. Key findings include: (1) thermal energy yield exceeds electrical output by 2.8 times owing to PV's low efficiency, while electrical exergy dominates thermal exergy by 5.3 times highlighting electric output's primacy; (2) electrical output chiefly depends on irradiation, while thermal energy and exergy are highly sensitive to ambient temperature and wind speed; (3) thermal energy escalates 4.5 times faster than electrical energy with irradiation rise, but thermal exergy drops sharply from 10.1 to 0.34 W as ambient temperature increases from 0 to 35 °C due to quality factor degradation. The study provides new generalized correlations, validated model, and extensive performance assessment to advance PCM-based PVT collector design.

Advancing solar-powered hybrid FO-MD desalination: Integrating PVT collectors and PCM for sustainable water production in residential building

The global focus on water desalination using solar energy is particularly pronounced today. Previous studies have affirmed the efficiency of the Forward Osmosis (FO) and Membrane Distillation (MD) hybrid desalination system. The Photovoltaic Thermal (PVT) solar system, which generates both thermal and electrical energy, is complemented using Phase Change Material (PCM). PCM, known for storing and releasing significant heat during phase change, is used in the evening to meet the thermal needs of the system. Additionally, an integrated battery system stores the electrical energy generated by PVT, ensuring the system's electricity requirements are sustained during the night. A comprehensive numerical model, PVT-PCM-FO-MD, has been developed to analyze the proposed system. Operating seamlessly under natural conditions for a typical day on March, June and September, the proposed system can produce freshwater continuously over a 24-hour period. To assess system performance, three PCM thicknesses (2 cm, 4 cm, and 6 cm) were employed. Designed for small-scale applications, this system is well-suited for brackish water desalination in remote areas. Notably, the highest water production recorded was 213.25 L during a 24-hour operation and the MD unit exhibited an impressive 83.78 % evaporation efficiency during the typical day on June, with nighttime efficiency reaching 37.07 %, specifically at 3 am, utilizing a 2 cm PCM thickness in the solar energy system and it was 37.22 % at the same hour and PCM thickness in September. This study further explores the impact of initial brackish water salinity on water production after 24 h and investigates the influence of the initial draw solution concentration in the draw tank on desalinated water production. The study found that despite varying initial salinity levels, the difference in water produced at the end of the day was not exceeding 1.6 L.

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.

Design and optimization of a hybrid cooling configuration combining PCM and liquid cooling for Li-ion battery using data-based response surface approximation model

Effective thermal management is crucial for safe operation of electric vehicles. This study proposes a novel hybrid cooling system that using phase change material (PCM) and liquid cooling to address issues such as leakage, non-uniform temperatures under high discharge rates. A comprehensive 3D model was developed to analyze the influence of geometric parameters on the cooling system. Response surface approximation modeling was used to optimize the layout parameters of the PCM. The results show that the hybrid cooling outperforms other methods, maintaining the cell temperature with 35 ℃ and the temperature difference within 4 ℃. The thickness of the PCM is a significant factor, as it increases heat storage capacity and reduces temperature; however, exceeding a certain threshold leads to increased thermal resistance. A non-uniform PCM layout can reduce the temperature difference by 26 %. An optimal PCM thickness of 2.5 mm to 3 mm ensures that the maximum temperature remains below 32.5 ℃, with a temperature difference within 2 ℃. The lowest temperature difference is achieved with a vertical layout height of 70 mm and a horizontal layout thickness of 3 mm. These findings are valuable for enhancing the thermal management of lithium-ion battery.

Simultaneous use of renewable energies and phase change materials to reduce energy consumption in Saudi buildings: Examine the photovoltaic cells

According to the Net Zero long-term plan, about 95% of the building's CO2 emissions should be declined by 2050 compared to 2020. In this study, focusing on “energy efficiency” and “renewables”- key pillars of the Net Zero plan-two techniques of adding photovoltaic cells (PVs) along with the loading of phase change material (PCM) to Saudi Arabian buildings were studied. In the first pillar, the installation of PV cells on all the horizontal/vertical envelopes was checked and it was found that in the same area, the electricity production on the roof is 136% more than the south-oriented vertical envelope and 1126% more than the north one. On the other hand, PVs on the roof reduce the cooling load by 5.8%, increase the heating load by 2.5%, and finally reduce the annual energy demand by 4.6% as a side effect. For the second pillar, PCM was installed in vertical/horizontal envelopes. As the thickness of PCM increases, annual energy consumption decreases, but at a lower rate. When the thickness of PCM reaches 15 cm, it is expected that it will have an energy savings of 9855 kWh/year, but the calculations exhibit a value of 4701 kWh, which demonstrates the fall in PCM effectiveness with thickness rise. The effect of PCM installation location had a very important effect. To reduce the cooling load, PCM should be installed in the outermost layer, and vice versa for the heating load, it should be installed in the innermost layer. When the annual analysis is prioritized, installing PCM in the outermost layer can perform better than the innermost layer up to 14.6%.

Collaborative Optimized Design of Glazing Parameters and PCM Utilization for Energy-Efficient Glass Curtain Wall Buildings

Glass curtain walls (GCWs) have become prevalent in office buildings, owing to their lightweight and modular characteristics. However, their lower thermal resistance, compared to opaque walls, results in increased energy consumption. Incorporating phase-change materials (PCMs) provides a viable solution through which to address the susceptibility of GCWs to external conditions, thus enhancing thermal performance and mitigating energy concerns. This study delves into the influences of the glazing solar heat gain coefficient (SHGC), the glazing heat transfer coefficient (U-value), and PCM thickness on the energy performance of buildings. Using Design Builder (DB) software version 6.1.0.006, a multi-story office building was simulated in different climatic zones in China, covering the climatic characteristics of severe cold, cold, hot summer and warm winter, cold summer and winter, and mild regions. The simulation results quantitatively elucidated the effects of the glazing parameters and the number of PCMs on thermal regulation and energy consumption. A sensitivity analysis identified the glazing SHGC as the most influential factor in energy consumption. Additionally, by employing Response Surface Methodology (RSM), the researchers aimed to achieve a balance between minimal building energy consumption and economic cost, ultimately determining an optimal design solution. The results demonstrated significant energy savings, ranging from 20.16% to 81.18%, accompanied by economic savings, ranging from 15.78% to 79.54%, across distinct climate zones in China.

Optimizing Waste Heat Conversion: Integrating Phase-Change Material Heatsinks and Wind Speed Dynamics to Enhance Flexible Thermoelectric Generator Efficiency.

Flexible thermoelectric generators (FTEGs) have garnered significant attention for their potential in harnessing waste heat energy from various sources. To optimize their efficiency, FTEGs require efficient and adaptable heatsinks. In this study, we propose a cost-effective solution by integrating phase-change materials into FTEG heatsinks. We developed and tested three flexible phase-change material thicknesses (4 mm, 7 mm, and 10 mm), focusing on preventing leaks during operation. Additionally, we investigated the impact of wind speed on the output performance of FTEGs with a flexible phase-change material heatsink. The results indicate that the appropriate flexible phase-change material thickness, when integrated with considerations for wind speed, demonstrates remarkable heat-absorbing capabilities at phase-change temperatures. This integration enables substantial temperature differentials across the FTEG modules. Specifically, the FTEG equipped with a 10 mm thick flexible phase-change material heatsink achieved a power density more than four times higher when the wind speed was at 1 m/s compared to no wind speed. This outcome suggests that integrating phase-change material heatsinks with relatively low wind speeds can significantly enhance flexible thermoelectric generator efficiency. Finally, we present a practical application wherein the FTEG, integrated with the flexible phase-change material heatsink, efficiently converts waste heat from a circular hot pipe into electricity, serving as a viable power source for smartphone devices. This work opens exciting possibilities for the future integration of flexible thermoelectric modules with flexible phase-change material heatsinks, offering a promising avenue for converting thermal waste heat into usable electricity.

Investigation of multifactorial effects on the thermal performance of battery pack inserted with multi-layer phase change materials

The safe and efficient power battery thermal management system (BTMS) is a prerequisite for the effectiveness and long service life of electric vehicles. So, a BTMS with inserted multi-layer phase change materials (PCMs) is proposed to enhance the safety and working performance of battery pack. Effects of PCM settings and operating conditions on the thermal performance of battery pack are discussed and analyzed. The results reveal that PCM cooling plays a significant role in the thermal management of battery pack, where the maximum temperature value and temperature difference of BTMS with multi-layer PCM #C are respectively reduced by 13.61 °C and 2.54 °C compared to battery pack without PCM. Besides, the coupling effects of multiple factors, that is, PCM permutation, the thickness and height of PCMs, and ambient temperature, on the heat dissipation of battery pack are discussed via orthogonal results analysis. The optimized multi-layer PCMs are obtained for the BTMS, i.e., Ps = 121, h1 = 5 mm and L = 6 mm, which achieves the lowest values of Tmax = 43.02 °C and ΔT = 3.37 °C at Tamb = 20 °C. It provides insights for optimizing thermal control strategies for the advancement of thermal management in electric vehicles, ultimately enhancing safety, performance, and longevity.

Numerical investigation of the heat-release performance of a metal hydride reactor-integrated phase change material

Metal hydride (MH) heat storage has a relatively high energy density and can be used in concentrated solar power (CSP) plants. However, in this system, the outlet temperature of the heat transfer fluid (HTF) has large fluctuations while discharging heat, which cannot satisfy the requirement of CSP plants. Therefore, this study proposes an MH-based heat storage system integrated with phase change materials (PCMs). A mathematical model was established to investigate the effects of the thickness of PCMs, HTF velocity, and the initial state of PCMs on heat-release performance. The results showed that the fluctuations can be effectively attenuated, and the fluid outlet temperature can be kept stable for a certain period by integrating PCMs. Plateaus in the curves of the MH bed and HTF outlet temperatures were observed, and the platform temperature and time are defined as the average temperature of two inflection points of the curve and their corresponding time difference, respectively. Increasing the thicknesses of PCMs can extend the platform time. Furthermore, the liquid phase of PCMs is conducive to improving the heat-release performance of the MH reactor with PCM.

Thermal performance of a solar heat collection and storage wall with night insulation in winter: A numerical study

The application of phase change material (PCM) in Trombe walls (TW) can improve all-day indoor thermal comfort. However, the heat loss via the glass is relatively large, resulting in low thermal efficiency at night. This paper designs a double glass and a thermal insulation curtain used to increase the thermal efficiency of a TW with PCM at night. In addition, a mathematical model based on the implicit difference method was established to study the thermal efficiency and heat loss of the proposed wall in Beijing. The findings indicate that the thermal efficiency at night is improved by 16.23 % compared to a traditional TW, while heat loss at night drops by 7.75 %. The heat gain at night first increased and then decreased with the augment of phase change temperature. As the latent heat or thermal conductivity of PCM increases, the heat gain declines during the day and increases during the night. The most suitable thickness of PCM is 0.02 m. The farther the insulation curtain is from the inner glass, the greater the heat loss and the smaller the indoor heat gain at night. And the later the opening time of the air vents during the day, the smaller the heat gain during the day and the greater the heat loss. But the resulting increase in nighttime heat gain is not significant. This study can offer design suggestions for enhancing indoor thermal comfort and nighttime insulation performance.

Coupling effect of radiative cooling and phase change material on building wall thermal performance

Phase change material (PCM) featured with high latent heat thermal energy storage capacity and isothermal phase transition is employed into building walls decorated with radiative cooling (RC) coating, in order to modify the cooling effect on building thermal performance. Numerical analysis indicates that the RC coating causes exterior temperature of P-RC walls lower than ambient temperature, achieving maximum exterior temperature drop of 13.63 °C. Thermal buffer effect of PCM enables to shave the temperature peak and shift the temperature valley, inducing exterior temperature of the P-RC wall to fluctuate slightly in comparison to the RC wall. Interior temperature of the P-RC wall is found to approach to target temperature tightly. PCM located closer to the outside completes phase transition more rapidly, which is beneficial to levelling radiative cooling of RC coating. Exterior temperature of P-RC walls increases with augment of solar radiation intensity, ambient temperature and indoor temperature. Augment of PCM thickness, ambient temperature or indoor temperature is conducive to interior temperature. Latent heat thermal energy storage of PCM enlarges effective thermal capacity of walls, which is favorable to maintain interior temperature within target temperature. In conclusion, studied results highlight that radiation cooling can be improved by PCM, with substantial benefits to develop passive cooling available to building energy conservation.

Numerical Investigation of Phase Change Material-Based Hybrid Battery Thermal Management System for Mass Optimization

In this work, a hybrid battery thermal management system using active cooling and Phase Change Material (PCM) has been studied. The additional weight of PCM poses design challenges, and hence its optimization is required. In this regard, a PCM enclosure of a cylindrical structure with six cylindrical cells is considered in 6-row and 1-column arrangement in the present work. The thermal performance of the proposed system is numerically investigated with different thicknesses of PCM layers at constant heat generation and coolant (air) flow rates. It is found that the battery thermal management with only PCM shows unsatisfactory performance under extended severe operating conditions. However, the addition low-flow convectional cooling improved the performance and the system’s reliability. It is found that for the proposed system, PCM thickness of 1 mm for the first battery cell and 2 mm for the subsequent battery cells help in better heat dissipation showing minimal thermal non–uniformity (1.1 °C) and reduced maximum temperature (39.6 °C) within the battery pack. Consequently, the optimized system shows 68.3% reduction in PCM mass as compared to the case of uniform thickness of the PCM.

Preliminary study of a dual channel solar photocatalytic ventilation wall system for year-round air purification and building energy savings

With the aim of meeting the weak adaptability to different seasons and low solar energy utilization efficiency for solar ventilation wall system. In the present work, a novel dual-channel solar photocatalytic ventilation wall (DSPVW) integrated with a photovoltaic (PV) panel and phase change materials (PCM) has been numerically proposed and simulated in winter and summer in subtropical climate zone. A range of performance indicators, such as outlet temperature, air heating gain, and clean air delivery rate (CADR), is evaluated. Furthermore, a comparative analysis is performed to assess the energy and exergy characteristics, distribution, comfortable temperature range percentage (CTRP), energy consumption and savings rate of three different systems: typical solar photocatalytic ventilation wall (SPVW), dual-channel solar photocatalytic ventilation wall (DSPVW), and DSPVW-PV/PCM. Results show that melting temperature of 313.15 K and 323.15 K respectively shows a good performance in winter and summer. The rate of temperature change and peak temperature to the outlet air slow down and decrease with the increase of PCM thickness, resulting in a cooling effect of 1.27 % and 2.83 % in winter and summer. In addition, the simulations with small channels exhibit poor thermal performance but better air purification effect, reaching total CADR as high as 69.46 m3 and 67.33 m3 respectively in winter and summer. Meanwhile, the energy consumption and energy saving rate of the DSPVW-PV/PCM is −3.09 kW and 75.7 %, respectively, compared to the SPVW system. This study could contribute to the widespread adoption and application of solar ventilation walls in regions with hot summers and warm winters.

Impact of Positioning Phase Change Materials on Thermal Performance of Buildings in Cold Climates

The building envelope, an essential component of any building, plays a critical role in meeting energy efficiency and thermal comfort requirements. Incorporating phase change materials (PCM) into the building envelope can offer an opportunity to minimize energy usage and enhance thermal comfort by offsetting daily temperature fluctuations. However, the optimal performance of PCM is contingent on the material’s placement and thickness within the building envelope. Therefore, this study investigated the effects of positioning and thickness of PCM on thermal comfort and heating loads in a lightweight timber building in Trondheim, Norway. Four scenarios were considered based on the positioning of the PCM layer in the exterior wall and roof. Using IDA ICE, parametric simulations were conducted for various PCM wallboard positions and thicknesses in the exterior wall and roof. In Nordic climates, adding PCM reduces the risk of annual overheating. The findings of this study showed that installing 75mm of PCM wallboard in the exterior wall’s inner layer reduced the annual heating load by 2.3%. Compared to the base case scenario, increasing PCM thickness reduced zonal maximum indoor air temperatures by up to 6.2°C. This study underscored the importance of carefully considering the placement and thickness of PCM in building envelopes for optimal performance.

Rate capability and Ragone plots for designing battery thermal management system based on phase change material

Phase change material (PCM), as a passive thermal regulation technology, is anticipated to mitigate the thermal challenges associated with anomalous temperature in lithium-ion batteries (LIBs). Nevertheless, the examination of its performance, i.e., energy and power density, has received limited attention in applications of battery thermal management system (BTMS). The primary aim of this work is to concentrate on the parametric optimization and performance assessment of BTMS utilizing PCM. Initially, a numerical model integrated paraffin/expanded composite and pouch battery is built and validated. Subsequently, a series of parametric studies are conducted to explore several aspects, including PCM type, expanded graphite loading, packing density, and PCM thickness. The thermal rate capability and Ragone plots are used to describe the specific energy and specific power of PCM. Based on that, the effects of PCM properties, geometry, and operating conditions can be effectively clarified. Furthermore, a multi-attribute decision making (MADM) method is introduced to aid variable selection. From analysis, the composite with PCM type of RT28, expanded graphite loading of 1–5 wt%, packing density of 700 kg m−3, and thickness of 3 mm is regarded as a suitable choice to achieve good performance. The present framework is helpful to provide guidance for PCM-based BTMS design.

Thermal performance of a hybrid cooling plate integrated with microchannels and PCM

The battery thermal management system (BTMS) is critical to electric vehicle (EV) safety and performance. In this paper, a novel cooling plate integrated with liquid microchannels and phase change material (PCM) is developed for use in BTMS, and its thermal performance at a high discharge rate of 5C is investigated. To improve temperature inhomogeneity, the non-metallic inlet shell is used to transport the coolant to the axial microchannels, which significantly reduces the temperature difference by 3.8 °C. Additionally, compared with I-shaped microchannels, the design of S-shaped microchannels increases the flow area for coolant and promotes the cooling effect, controlling the maximum temperature at 34.53 °C. Then, the parameters, including the number of microchannel layers, radial extension angle, inner diameter, and PCM thickness, are optimized by the multi-objective optimization, and its energy consumption is decreased to 9.61 × 10-6Wh and its energy density raised to 108.94 Wh∙kg−1. Moreover, the cooling performance improves with the increase of the inlet velocity, and a balance between cooling performance and energy consumption is achieved when the inlet velocity is 0.06 m∙s−1. Cross-convectional flow helps to enhance the temperature uniformity of the battery module further. The hybrid liquid cooling plate takes advantage of coupling active cooling and passive cooling; the energy consumption of BTMS is reduced by 46.3% without sacrificing the cooling capacity when delaying the beginning of active cooling after PCM passive cooling for 300 s. Furthermore, the PCM-embedded hybrid cooling plate slows the heat loss of batteries in cold environments, which can maintain their temperature above 20 °C after resting for 2 h at 0 °C. This work provides a reference for the hybrid cooling plate development of cylindrical batteries.

A phase change material (PCM) based novel retrofitting approach in the air conditioning system to reduce building energy demand

Improvement in air quality and reduction of airborne diseases can be effectively achieved by inducing fresh air into the building. However, this challenges the building’s energy consumption. As a proposed solution, the present study dwells into the use of phase change materials (PCM), a heat-based exchanger, as a retrofit with a Heating Ventilation and Air-conditioning system (HVAC), to extract thermal energy from fresh air and consequentially diminish the energy demand. Calcium chloride hexahydrate (CaCl2·6H2O) is used as PCM, selected by TOPSIS method based on entropy weights. The energy saved in the augmented PCM thickness (from 20 mm to 100 mm) and added longitudinal fins (5 mm in width and 50 mm in length) is assessed in comparison to the standard HVAC systems utilizing R134a. For summers in composite climate, the HVAC system retrofitted with a heat exchanger with 100 mm PCM thickness 48 fin configuration achieved peak and average energy savings of 12 % and 9 %, respectively, when the system operated for 6 h. For PCM thicknesses of 75 mm, 50 mm, and 20 mm, the maximum energy savings were 6.64 % with 48 fins, 5.22 % with 24 fins, and 3.22 % with 12 fins, respectively. The study provides policymakers with energy-efficient and sustainable solutions for HVAC systems, which can reduce energy demand and help combat climate change.

Effects of heating film and phase change material on preheating performance of the lithium-ion battery pack with large capacity under low temperature environment

In this work, a preheating management system for large-capacity ternary lithium battery is designed, where a novel coupling preheating method of heating film and phase change material (PCM) is employed to preheat. In order to make the preheating system meet the preheating requirements of the battery pack, effects of four influencing factors (heating film power, heating film power difference, cell spacing and PCM thickness) on preheating of the battery pack are studied numerically. Then, the relationship between four factors and preheating time and temperature difference is found, and the optimum parameters in the coupled preheating management system are obtained based on simulation. Finally, the preheating schemes of conventional preheating and rapid preheating under low ambient temperature are determined and investigated. The results show that rapid preheating takes much less preheating time than conventional preheating, where the temperature difference is about 1.48 K and the time consumption is 602 s, 518 s and 394 s under the low temperatures of 253.15 K, 263.15 K and 273.15 K, respectively. In addition, this preheating scheme also prove the feasibility of the designed battery pack thermal management system, which can meet the actual use of electric vehicles.

Computational analysis of preheating cylindrical lithium-ion batteries with fin-assisted phase change material

The existing conventional vehicle transportation landscape in India is grappling with challenges stemming from extensive air pollution, health risks, surging oil prices, limited fossil fuel resources, substantial oil import expenses and energy volatility. To counter these issues, Electric Vehicles (EVs) are progressively replacing internal combustion engines, offering a promising route toward decarbonization and mitigating climate concerns. EVs rely on electric motors powered by batteries, predominantly Lithium-ion batteries (LIBs), known for their superior attributes such as low self-discharge, high energy density and extended life cycle. Nevertheless, LIB performance is significantly influenced by operating temperatures, with suboptimal conditions leading to decreased efficiency, power loss and faster aging. Addressing this, an effective Battery Thermal Management System (BTMS) becomes crucial to maintain batteries at optimal temperatures, enhancing their efficiency and safety. This study focuses on a computational analysis of passive heating systems employing Fins and Phase Change Materials (PCM) for 18650 Li-ion battery thermal management at low temperatures, with specific attention to battery module analysis. Numerical analysis using ANSYS FLUENT investigates the influence of varying PCM thickness on heat transfer, predicting temperature distribution and discussing its impact on battery output performance.

Determining the optimal location and thickness of phase change materials in the building walls: an energy-economic analysis

Determining the optimal location and thickness of phase change materials in the building walls: an energy-economic analysis