Thickness Of Phase Change Material Layer Research Articles

Experimental and Numerical Investigation for Optimization of a Hybrid Battery Thermal Management System based on PCM and Air Convection

Abstract This work presents the design and optimization of a phase change material (PCM) based hybrid battery thermal management system (HBTMS). In the first stage, experiments are performed to measure the battery cell temperatures under various charge rates with and without the usage of PCM. Thereafter, a numerical model is developed to conduct a parametric study on the effect of thickness of PCM layer around the battery cell. The maximum cell temperature (36.35°) and thermal nonuniformity are within the safe range for the PCM thicknesses of 6 to 12 mm. In the second stage, a parametric study is conducted in the 6S1P battery module to optimize the spacing between the cells at constant inlet velocity. The maximum temperature is within the optimal range when the cell spacing is 10 mm. At the constant cell spacing of 10 mm, increase in inlet velocities from 0.25 m/s to 2.5 m/s gradually improves the thermal non-uniformity. The maximum temperature and thermal non-uniformity for 6S1P battery module is found to be 42.07° and 1.17° respectively. In the third stage, 6S1P battery module is optimized for PCM thickness, cell spacing and inlet air velocity. It is found that effective thermal management is possible with PCM based HBTMS at low airflow rate of up to 1.5 m/s. The optimized PCM based HBTMS shows 46.59% and 40% reductions in PCM mass and air flow rate respectively.

Experimental and numerical study on the thermal performance of earthbag-wall units incorporated with phase change materials

The demand for temporary housing for refugees and displaced communities has led to the development of earthbag buildings. While these structures are affordable and sustainable, they often struggle with thermal discomfort in extreme climates. This study aims to examine the integration of phase change materials (PCM) into earthbag walls to improve thermal performance. The research involved incorporating paraffin wax and microencapsulated PCM into scaled-down earthbag walls, with their performance evaluated in a controlled environment. The results were validated against a numerical simulation model developed in EnergyPlus. The study revealed significant thermal improvements with PCM integration. Wall-2, with paraffin wax A31, demonstrated a surface temperature reduction of up to 1.9 °C, while Wall-3, with microencapsulation Inertek26, showed a decrease of 2.4 °C compared to the reference wall. A parametric analysis highlighted the importance of PCM layer thickness. Specifically, Wall-2 with a 6 cm paraffin wax layer achieved a maximum reduction of 4.0 °C compared to the base case. The study identified the transition temperature of PCM as a critical factor in thermal performance, with paraffin wax A31 emerging as the optimal choice. Placing the PCM layer on the interior surface of the wall was more effective than exterior placement. Overall, PCM integration in earthbag walls offers a promising solution to enhance thermal comfort in temporary housing, addressing the critical needs of refugees and displaced communities. This research fills existing gaps in thermal comfort in temporary housing and demonstrates the potential of PCM as an innovative passive design strategy.

Optimization of temperature distribution in building envelopes of Ahmedabad region using nano-encapsulated phase change material

The incorporation of Phase Change Materials (PCM) into the building envelopes helps to increase indoor thermal comfort while lowering energy usage. The selection of PCM is directly related to its performance and might be viewed as an optimization challenge. The manuscript highlights the optimization of temperature distribution in building envelopes (walls and roofs) of Ahmedabad by choosing the suitable PCM and Nano-particle. Three different PCMs (RT31, RT 35, and RT42) and Nano-particles (Al2O3, CuO, and ZnO) with different concentrations (12 %, 16 %, and 20 %) are considered for the optimization. The PCMs are encapsulated into the building layer thickness to examine their characteristics like effective thermal conductivity, concentration, melting point, etc. These parameters are evaluated in a room that measures 5 m x 4 m x 3.5 m (L x W x H). The design-builder software (Version 7.0.2.006) is used to carry out the steady-state numerical simulations for this building envelope. The results suggest that the integration of PCM reduces the building's overall energy consumption by 7.92 kWh/m2 per year. The optimal design is proposed by establishing a temperature difference (ΔT) in building envelopes and utilizing a hybrid optimization technique (a combination of Artificial neural network (ANN) and Genetic algorithm (GA)). This temperature difference of the building envelope is confirmed to be dependent on their PCM melting point, effective thermal conductivity, concentration (in%), and PCM layer thickness. Hybrid optimization is found to be the most stable strategy for predicting temperature dilation and energy storage in building envelopes. Thus this paper gives a systematic understanding of the selection of PCM and Nano-particles and identifies the suitable PCM layer thickness for encapsulation.

The effect of PCM layer thickness and coolant mass flow rate on the efficiency of a double-channel photovoltaic/thermal-PCM system: Numerical and artificial neural network analysis

A photovoltaic/thermal (PV/T) system containing a phase change material (PCM) layer located between two parallel air flow channels was numerically studied in the present research. With numerous numerical simulations, the effect of PCM layer thickness (ϕ=5–30 mm) and air mass flow rate (m˙a=0.0123–0.0368 kg/s) on system efficiency were determined. It was found that from the thermal point of view, it is better to have a smaller thickness of the PCM layer, while from the electrical point of view, the average thickness is more effective. The highest thermal efficiency (22.95–59.42 %) and the highest electrical efficiency (16.05–16.79 %) occurred in ϕ=5 mm and ϕ=20 m, respectively. Also, it was revealed that the increase in m˙a is associated with an increase in the overall efficiency. Among the examined cases, the highest overall efficiency (39.64–77.66 %) belonged to case of ϕ=5 mm and m˙a=0.0368 kg/s. After identifying this point, the artificial neural network method was used to determine the relationship that can predict the optimal overall efficiency at different hours and at different m˙a with an acceptable accuracy.

Enhanced performance of photovoltaic thermal module and solar thermal flat plate collector connected in series through integration with phase change materials: A comparative study

The decline in photovoltaic cell efficiency due to temperature elevation, coupled with solar energy's inherent intermittency, presents challenges for solar systems, including photovoltaic panels and solar thermal (ST) collectors. The integration of phase change materials (PCMs) emerges as a promising solution to enhance thermal energy storage and regulation, thereby improving system performance and sustainability. This study investigates the performance of series-connected photovoltaic thermal (PVT) and ST systems with integrated PCMs from energy and exergy viewpoints, utilizing a 3D transient numerical simulation. The proposed system's performance is compared with that lacking a PCM across various heat transfer fluid mass flow rates. Suitable PCM selection based on melting temperature is explored, along with PCM layer thickness and nanoparticle augmentation. The research highlights that PCM integration effectively regulates PV cell temperature, enhancing electrical power and exergy rate. While increasing the mass flow rate improves thermal and electrical power, it reduces the thermal exergy rate. Comparing different PCMs (RT28 HC, RT35 HC, and RT44 HC), the RT28 HC PCM provides the lowest temperature of PV cells and the best electrical performance during the day. Moreover, increasing PCM layer thickness results in lowering PV cell and outlet temperatures and storing more heat. Nanoparticles added to PCMs lead to a marginal improvement in energy and exergy, especially for the system with RT28 HC. This analysis emphasizes PCM integration's role in enhancing solar thermal system performance, highlighting the importance of considering the PCM's melting temperature for effective thermal energy management.

Phase change material as a heat sink for solar photovoltaic: A numerical study on the thermo‐physical properties and thickness effects under actual weather conditions

AbstractThis numerical study examines the thermal performance of solar photovoltaic (PV) with phase change material (PCM) as a heat sink under real ambient conditions. A mathematical model is developed to assess the comparability between PV and PV with PCM in a one‐dimensional unsteady state condition. The influence of PCM properties such as density, thermal conductivity, melting point temperature, and latent heat on the thermal performance of PV module is analyzed. The impact of altering PCM layer thickness is also explored. Results show that the PV‐PCM system can keep a nominal operating temperature for a longer duration of energy generation, which enhances the efficiency and lifespan of the PV module. The peak solar cell temperature for conventional PV without PCM is 81.8°C at 12.15 pm, while for PV with PCM, it is 74.8°C at 12.40 pm, indicating a reduction of 6.9°C or 9.3%. The deviation of maximum temperature between standard PV and PV‐PCM systems is 24.8°C or 35% diminished temperature, achieved at 10 am.

A Novel Molecular PCM Wall with Inorganic Composite: Dynamic Thermal Analysis and Optimization in Charge-Discharge Cycles.

The combination of electric heating and thermal energy storage (TES) with phase change material (PCM) can achieve load shifting for air conditioning energy saving in building sectors. Their non-flammability, relatively good mechanical properties, and low cost make inorganic PCMs attractive in construction engineering. However, PCMs often show poor thermal conductivity, low heat transfer efficiency, leakage risk, etc., in applications. Moreover, the practical thermal performance of PCM-TES sometimes fails to meet demand variations during charge and discharge cycles. Therefore, in this study, a novel integrated electric PCM wall panel module is proposed with quick dynamic thermal response in space heating suitable for both retrofitting of existing buildings and new construction. Sodium-urea PCM composites are chosen as PCM wall components for energy storage. Based on the enthalpy-porosity method, a mathematical heat transfer model is established, and numerical simulation studies on the charge-discharge characteristics of the module are conducted using ANSYS software. Preliminary results show that the melting temperature decreases from 50 °C to approximately 30 °C with a 30% urea mixing ratio, approaching the desired indoor thermal comfort zone for space heating. With declining PCM layer thickness, the melting time drops, and released heat capacity rises during the charge process. For a 20 mm thick PCM layer, 150 W/m2 can maintain the average surface temperature within a comfort range for 12.1 h, about half the time of a 24 h charge-discharge cycling periodicity. Furthermore, placing the heating film in the unit center is preferable for improving overall heat efficiency and shortening the time to reach the thermal comfort temperature range. This work can provide guidance for practical thermal design optimization of building envelopes integrated with PCM for thermal insulation and energy storage.

Energy performance based optimization of building envelope containing PCM combined with insulation considering various configurations

Phase change material (PCM) is considered as a promising solution for reducing heating and cooling energy consumption by integrating them into the building envelope, which in turn reduces CO2 emissions. In this paper numerical simulations were carried out to evaluate the energy performance based optimization of envelope building integrated PCM. The effect of several parameters (PCM melting temperature, PCM layer combined with insulation, PCM layer and insulation layer thickness, double PCM layer system in the double external wall, and air layer interaction with PCM in roof) on energy savings in two typical models of residential buildings in Tunisia are investigated. Results show that energy demand reduction of 73.81% and 76.46% can be achieved under the optimal conditions of application of the PCM integrated in simple wall and double wall buildings respectively. This is associated with significant reduction of CO2 emission. Moreover, PCM layer performance is improved by increasing its thickness with an optimal value of 6 cm. Two PCM layers located in the middle of the double wall involve higher energy saving than a simple PCM layer.

Optimizing PCM Integrated Wall and Roof for Energy Saving in Building under Various Climatic Conditions of Mediterranean Region

Energy conservation in buildings has been the focus of many studies since nearly one-third of global energy consumption is due to buildings. Phase change material (PCM) technology promises to be an attractive solution for energy saving in buildings since it is a passive and effective technology, as demonstrated in the literature. Therefore, this study focuses on the energy-saving performance of PCM-integrated buildings located in a Mediterranean climate to reveal their energy-saving potential. PCM is integrated both in external or internal south walls and roofs of buildings under four different climatic conditions. EnergyPlus, which is a well-known building simulation software, is adopted for building thermal analyses. The effects of melting temperature, location of PCM layer in the wall, thickness of PCM layer, type of envelope (wall or roof), and PCM double-layer system in the wall are investigated. The corresponding energy savings and CO2 emission reductions are obtained for the considered cases. The results showed that up to 41.6% reduction in energy demand can be obtained depending on the PCM application. Besides, PCM with a low melting temperature (21 °C) favored heating energy savings, while PCM with a high melting temperature (29 °C) favored cooling energy savings. Moreover, the double-layer PCM system provided higher energy savings than the single-layer PCM system, especially in warm and arid regions (Sousse and Tozeur).

Investigation of the Effect of Air Layer Thickness on the Thermal Performance of the PCM Integrated Roof

Recently, Phase Change Materials (PCM) have become more prevalent in improving buildings’ thermal management. The relative location of the PCM layer is a valuable measure for assessing the thermal performance of building envelopes, in addition to meteorological circumstances and PCM qualities. The optimum air layers between the PCM layer and roof may significantly reduce energy consumption in buildings. In this regard, the influence of air gap layer thickness on the thermal performance of a PCM (HS 29) integrated roof of the test room is investigated experimentally. Experiments are carried out for an unconditioned test room located on the terrace of a laboratory in Surat, India, considering various air layer thickness values (0, 2, 4, and 6 cm) and a fixed PCM layer thickness. Different configurations within the research, including no- PCM and PCM with 0, 2, 4, and 6 cm air layer thickness, are investigated for the effects of diurnal change in room temperature. Results are evaluated based on the peak value, valley value temperatures of different roof layers, and an index (MKR, Measure of Key Response). It is observed that the maximum temperature difference between the PCM-integrated test room and the non-PCM test room is 4 °C to 7 °C. Results showed that, with a higher MKR index of 8.83, a PCM-integrated roof with a 2 cm air layer thickness could reduce the diurnal room temperature variations compared with the non-PCM test room. This conclusion from the current research demonstrates the significance of an air layer provided between the PCM layer and the roof of the building.

Application of Artificial Intelligence to Improve the Thermal Energy and Exergy of Nanofluid-Based PV Thermal/Nano-Enhanced Phase Change Material

Photovoltaic-thermal (PVT) technologies have demonstrated several attractive features, such as higher power and comparative efficiencies. Improving the thermal recovery from the PVT system would further improve the power output and the efficiency of the PVT system. This paper identifies the best operating factors of nanofluid-based PV thermal/nano-enhanced phase change material using artificial intelligence. The target is the maximization of thermal energy and exergy outputs. The suggested approach combines ANFIS modelling and particle swarm optimization (PSO). Four operating factors are taken into consideration: PCM (phase change material) layer thickness, HTF (heat transfer fluid) mass flow rate, MFNPCM (“mass fraction of nanoparticles in PCM”) and MFNfluid (“mass fraction of nanoparticles in nanofluid”). Using a dataset, an “adaptive neuro-fuzzy inference system” (ANFIS) model has been established for simulating the thermal energy and exergy outputs in terms of the mentioned operating factors. Then, using PSO, the best values of PCM thickness, mass flow rate, MFNPCM and MFNfluid are estimated. The proposed model’s accuracy was examined by comparing the results with those obtained by response surface methodology and the experimental dataset.

Periodic energy transmission and regulation of photovoltaic-phase change material-thermoelectric coupled system under space conditions

Phase change material (PCM) as highly efficient temperature control material has been used in photovoltaic-thermoelectric (PV-TE) coupling system to achieve higher power generation efficiency. The periodic energy balance and PCM regeneration are the key factors that affect the temperature control effect and system total performance. In present paper, a numerical model for space PV-PCM-TE system was established with the composite of paraffin and aluminum foam as PCM. Firstly, the impact of periodic energy imbalance on PCM regeneration characteristics and system overall performance was investigated under space conditions. Then, to regulate the periodic energy transmission of the coupling system, a global structural parameters optimization was performed, and the optimal parameter combination was derived and validated, where porosity of aluminum foam, thickness of PCM layer, thermal concentration factor, length of TE legs, and surface area ratio are 0.94, 4.08 mm, 25.83, 1.09 mm and 1.80, respectively. The validation results show that after optimization, the periodic energy balance and PCM full utilization and regeneration can be achieved. The average total efficiency of optimal case is 30.72%, which is a little lower than that with the surface area ratio of 7.0 (31.77%), but the average power density is 49.64% higher. The present work validates that periodic energy balance design is important for space PV-PCM-TE system and the global parameter optimization method is an effective optimization method, which is significant for the design and optimization of PCM based temperature control system.

Performance evaluation of a novel rotatable dynamic window integrated with a phase change material and a vacuum layer

A glass window filled with a phase change material (PCM) can effectively increase the thermal inertia of a building envelope and achieve peak load transfer. However, conventional PCM windows have low energy efficiency, and the PCM layer has a risk of overheating. To improve the building energy efficiency and avoid the overheating of PCM windows, a new type of rotating dynamic PCM window (DPCMW) was designed in this study. The window comprised a PCM layer and a vacuum glass layer. The DPCMW could adjust the relative position of PCM and vacuum glass layers according to the time; thus, the heat flux direction could be changed to reduce the building load. A theoretical model of the DPCMW was established and verified. The performance of the DPCMW was investigated under the Cfa climate, and the effects of the phase transition temperature, PCM layer thickness, and PCM phase transition temperature range on the performance was discussed. The results indicate that the performance of the DPCMW exceeds that of a static PCM window (SPCMW) in both winter and summer. The DPCMW reduces the heating load relative to the SPCMW by 12.40% in winter and reduces the cooling load relative to the SPCMW by 93.79% in summer. The DPCMW reduces the annual building load by 28.70% relative to the SPCMW. Additionally, the optimal phase transition temperature is 23–25 °C. The thicker the PCM layer, the better the energy-saving effect, and the optimal phase transition temperature range is 19–25 °C. This study provides a theoretical basis for the application of the DPCMW.

Energy consumption of a building with phase change material walls – The effect of phase change material properties

The use of Phase Change Material (PCM) in the building envelope is a promising technology for providing energy savings. In this study, the effectiveness of incorporation a honeycomb PCM to the walls of a retrofitted building in Ottawa, Canada is investigated in terms of reduction of heat flux through the walls. The climatic condition of Ottawa has a low air temperature of about −14 °C in the winter season. Reduction in the heat flux through the building envelope reduces the energy consumption of the building. PCM melting temperature, peak effective capacity, and the thickness of PCM layer have been varied to study their respective effect on the effectiveness of the PCM. Incorporating 1-cm thick PCM with peak melting temperature of 20 °C gives the best performance for a typical summer day with outdoor temperature varying from 15.0 to 26.5 °C. The heat gain and heat loss through the studied building walls is reduced by 41 % and 96 %, respectively. Also, the results show no further improvement in the PCM effectiveness when the thickness of the PCM layer and the peak effective heat capacity are increased beyond 1 cm and 20 kJkg−1K−1, respectively.

Thermo-economic evaluation of PCM layer thickness change on the performance of the hybrid heat storage tank for concentrating solar power plants

The current research examines how increasing the thickness of the phase change material (PCM) layer impacts the thermal and economic behavior of the hybrid sensible-latent heat storage reservoir utilized in solar power plants in order to prevent temperature fluctuations at the end of discharge cycles. On the basis of two-phase dispersion-concentric equations, a detailed transient numerical analysis is developed. The mathematical model equations are computed using the MATLAB program, and the present numerical findings are validated. Numerical investigations are used to compare the proposed storage system to the sensible heat storage (SHS) system in the context of cost and efficiency. The impact of various performance evaluation indexes, including axial temperature allocation, thermocline layer degradation, charging time, discharging time, and overall efficiency, are investigated. The results showed that the (35% PCM-30% SHS-35% PCM) configuration possesses the most considerable thermocline thickness of 7.94 m at the charge period of 360 min, while the SHS case has 3.2 m thermocline thickness at the charge period of 420 min. Due to its optimized efficiency, reduced thermocline area, and comparatively low cost, the (15% PCM-70% SHS-15% PCM) configuration demonstrates a more viable choice among the considered cases.

Determination of the inner forms of hollow blocks containing phase-changing material for different climate regions

Hollow blocks are used widely in buildings for their lightweight construction and high thermal resistance characteristics. When used with a phase change material (PCM), these blocks can reduce the heating and cooling loads of buildings compared to conventional hollow blocks. However, it is essential that the block inner forms and PCMs should be selected based on climate conditions. In this study, hollow blocks containing PCM in different climate types are thermally analysed. In the first step, ten different formed blocks are thermally analysed. In these blocks, the effects of hollow ratio (HR), inner form, and the number of cavities on heat flux and temperature distribution are investigated. The inner form of the hollow block with the least heat flux is determined in this step. The second step consists of optimization for the PCM melting temperature and layer thickness for the different provinces. The optimization results are evaluated on a building in terms of primary energy consumption and global costs. The best performing locations of the PCMs within the block are defined for all provinces in the last step. The results of the study are discussed in terms of the block surface temperatures and liquid fraction. The best PCM locations are found close to the block’s centerline in hot and warm climates and close to the indoor side in cold climates.

Utilization of a phase change material with metal foam for the performance improvement of the photovoltaic cells

This study presents a novel configuration for improving the photovoltaic (PV) panel's thermal management system, which includes a phase change material (PCM) with the metal foam layer. During the energy-absorbing mode, the arrangement allows for quicker heat dissipation from the system, resulting in the cooling of the PV panels. The effects of the foam-layer material, PCM thickness, and foam porosity are numerically simulated and analyzed. The results demonstrated that the higher PCM layer thickness leads to a lower PV surface temperature. The extracted curves indicated that lower porosity causes higher maximum PV temperature. Furthermore, it was found that average electrical efficiency for the model with a porosity of 0.9, 0.8, 0.4, and no-foam state are 13.805%, 13.794%, 13.761%, and 13.714%, respectively. All data are almost similar for both copper and aluminum foams, and there are negligible differences between the results. The results for the four chosen months describe that for June, March, and September, the PCM layer absorbs heat and causes a considerable reduction in the PV maximum temperature, but for December, this process is not valid. Accordingly, superior PCM-based thermal management is achieved through the proposed system.

Numerical Study to Investigate the Thickness of the PCM Layer for the Three Layers Tank for the CSP Plants

In the present study, the phase change material (PCM) layer thickness of the top and bottom PCMs change gradually with constant the middle PCM layer thickness for the three-layers thermocline thermal energy storage (TES) tank. It has been studied using spherical capsules packed with three types of PCMs with different thermophysical properties. A transient two-phase dispersion-concentric (D-C) model is used to calculate the process of phase change inside pellets to identify the temperature allocation. The method of heat transfer among molten salt and PCMs capsules is extensively discussed, with multiple numerical results shown. The results show that the thickness of the PCM layer has a high impact on the thermal performance of the TES tank. As the layer thickness of the top PCM increases, the time required to discharge the thermocline TES tank increases. The (80 % high phase change material (HPCM) -10 % intermediate phase change material (IPCM) - 10 % low phase change material (LPCM)) configuration has 14.6 %, 27.2 %, and 46.8 % higher overall efficiency than (33.3 % HPCM - 33.3 % IPCM -33.3 % LPCM) configuration, (70 % HPCM - 10 % IPCM - 20 % LPCM) configuration, and (10 % HPCM -10 % IPCM - 80 % LPCM) configuration. In contrast, the (80 % HPCM - 10 % IPCM - 10 % LPCM) configuration shows the highest capacity and utilization ratio.

A parametric study on the thermal response of a building wall with a phase change material (PCM) layer for passive space cooling

This paper presents a parametric study on the thermal response of a building wall outfitted with a phase change material (PCM) layer for passive space cooling. The effect of six factors was studied via heat flux reductions. The factors were (1) outdoor air temperature, (2) indoor air temperature, (3) insulation level, (4) PCM layer thickness, (5) PCM layer location within the wall cavity, and (6) PCM phase transition temperature. A numerical model, which was verified against experimental data, was developed for this purpose. It was found that an optimal PCM layer location range, which results in heat flux reductions higher than 50%, existed within the wall cavity for each outdoor-indoor air temperature difference. It was determined that PCM layer location within the wall cavity was a first order parameter. As the thermal resistance of the wall insulation increased, the optimal location of the PCM layer shifted slightly toward the outside of the wall. As the PCM layer thickness increased, peak heat flux reductions increased up to a point after which the performance decreased. For the studied cases, the optimal PCM layer thickness was 7 mm. For better results during space cooling, it was observed that the PCM phase transition temperature should be in the range of 27 °C - 31 °C when the indoor air temperature was set at 24 °C.

Thermal Analysis and Parametric Investigation of Phase Change Material-Air Cooled Lithium Ion Battery Pack

Abstract A parametric analysis has been conducted for the phase change material (PCM)-air cooled battery pack. The system is composed of 26650 lithium-ion LiFePO4 batteries enclosed by PCM. A one-dimensional thermal model for the PCM domain is developed using the enthalpy method. The finite volume method is employed to solve the energy equation for both cell and PCM domain. The developed computational algorithm has been validated as a result of the simulations for the same conditions with the literature. The discharge process of the batteries has been investigated for 2C, 3C, and 5C rates. Thermal analyses have been performed for passive (natural convection) and active cooling (forced convection). It is aimed to keep the temperature of the battery cell under critical levels. A parametric investigation for crucial parameters like PCM layer thickness, the thermal conductivity of the PCM, arrangement of the batteries has been performed. Simulations have been conducted for the constant air velocity and the pumping power. Thanks to the constant pumping power analysis, thermally best-performing configuration have been sought by eliminating the hydrodynamic effect.