Types Of Phase Change Materials Research Articles

Incorporation of Phase Change Materials in Buildings

This review paper explores the integration of phase change materials (PCMs) in building insulation systems to enhance energy efficiency and thermal comfort. Through an extensive analysis of existing literature, the thermal performance of PCM-enhanced building envelopes is evaluated under diverse environmental conditions. This review highlights that PCMs effectively moderate indoor temperatures by absorbing and releasing heat during phase transitions, maintaining a stable indoor climate. This paper also delves into the detailed concepts of PCMs, including their classification and various applications within building insulation. It is noted that different types of PCMs have unique thermal properties and potential uses, which can be tailored to specific building requirements and climatic conditions. Furthermore, cost–benefit and environmental assessments presented in the reviewed studies suggest that incorporating PCMs into building materials offers significant potential for reducing energy consumption and mitigating environmental impacts. These assessments indicate that PCMs can lead to substantial energy savings by decreasing the reliance on heating and cooling systems, thereby lowering overall energy costs and carbon emissions. However, despite the promising outlook, this review identifies a need for further research to optimize PCM formulations and integration methods. This optimization is essential for overcoming current challenges and facilitating the widespread adoption of PCMs in the construction industry. Addressing issues such as long-term durability, compatibility with existing building materials, and cost-effectiveness will be crucial for maximizing the benefits of PCMs in enhancing energy efficiency and sustainability in buildings. Overall, this review underscores the transformative potential of PCMs in building insulation practices. By providing a comprehensive overview of PCM classifications, applications, and their impacts on energy efficiency and environmental sustainability, this paper lays the groundwork for future advancements and research directions in the field of PCM-enhanced building technologies.

Enhancing MIMO-VLC system performance using reflective phase change materials

Abstract In this paper, the impact of phase change materials (PCM) as reflecting surfaces on the bit error rate (BER) performance of multiple-input multiple-output (MIMO) visible light communication (VLC) systems has been investigated. The optical properties of PCM, including absorption and reflection characteristics have been analyzed to optimize the design and functionality of PCM-based VLC systems. The current study investigates the BER performance of 4 × 4 and 8 × 8 MIMO-VLC systems using non-line of sight (NLoS) signal under varying refractive index, temperature, and incidence angle conditions. Additionally, different types of PCM has been assessed, such as organic compounds, salt hydrates, and paraffin wax, to determine their suitability for implementation in MIMO-VLC systems.

Thermal performance and flash point analyses of concentrator photovoltaic (CPV) system using multiple types of PCMs and various panel inclination angles under the effect of a constant heat flux

This numerical study conducts a comparative analysis of various phase change materials (PCMs) including Lauric Acid, Paraffin, RT 24, RT 31, RT 35, RT 38, RT 42, RT 47, RT 50, and Lithium Nitrate Trihydrate (LiNO3.3H2O) to assess their suitability for optimizing the thermal management of a solar concentrator photovoltaic (CPV) system. The analysis focuses on the temperature regulation capabilities, melting dynamics of the used PCMs, along the electrical efficiency of the CPV system across a range of inclination angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) under a constant heat flux of 1000 W/m². The research aims to identify the most effective solutions for enhancing the efficiency and reliability of solar concentrator systems. Key considerations such as PCM’s flash points, liquid fraction and convective behavior are addressed for each PCM type. Numerical results obtained using ANSYS Fluent indicate that Lithium Nitrate Trihydrate (LiNO3.3H2O) outperformed most paraffin-based PCMs, such as RT 24 and RT 35, with around 24 % higher electrical efficiency. Although Lauric Acid was approximately 19.5 % less efficient than Lithium Nitrate Trihydrate, it offered superior long-term thermal stability due to its slower melting rate and phase change temperature of 43–44°C, taking 45.33 % longer to melt compared to Paraffin RT 24. RT 50, with its higher melting temperature of 50°C, provided a balance between melting period and efficiency, making it an ideal PCM for applications requiring both moderate efficiency and sustained thermal regulation.

Energy and exergy analysis and performance optimization of buildings integrated with transpired solar collectors and phase change materials

Transpired solar collectors (TSCs) are one of the cost-effective air heating technologies that can be easily installed on building facades to provide heated fresh air to condition indoor space. The economics of TSCs can be further enhanced by integrating with phase change materials (PCMs). This study presents the performance investigation and optimization of a building-integrated TSC and PCM system (TSC-PCM). The interactions between PCM thermal properties, their locations in the building envelope, and TSC design parameters were investigated. Based on the modeling of the TSC-PCM by using energy balance and enhanced enthalpy method, a series of orthogonal tests, which varied PCM type, thickness, and location within building envelopes, and TSC suction flow rate were conducted. Multivariate testing, through the Taguchi method, was then applied to identify the optimal design combination. The results showed that the suction flow rate of the TSC-PCM on the external wall showed the highest influence on enhancing indoor thermal performance (up to 77.6%), followed by PCM location on the external wall (up to 9.2%). The optimized TSC-PCM system improved the thermal comfort increase index (TCI) to 3.7 and achieved a maximum thermal efficiency of 401.8%, with an exergy improvement of 26.9% in comparison with the use of the TSC-only. The optimized TSC-PCM system increased the average indoor room temperature to 18.8 oC, which was 6.8% and 18.2% higher than the use of the TSC-only and a baseline without using PCM and TSC, respectively.

An experimental study on performance improvement of concentrated photovoltaic (CPV) systems using phase change materials (PCMs)

This study was conducted experimentally to investigate the effect of cooling on the efficiency of concentrated photovoltaic (CPV) systems using phase change materials (PCMs). The influence of the type of PCM, sun concentration factor, and volume of the cooling tank was also examined. An experimental setup was built to test the CPV system. A concentrator with a surface area of 0.36 cm2 and a panel with dimensions of 7 × 13 cm2 were utilized. A cooling tank was used behind the panel that was filled with PCM and latently absorbed the heat produced by the panel during electricity generation. The results showed that using PCM with higher latent heat led to better results. Also, increasing the concentration factor and increasing the volume of the cooling tank increased the system power. It was indicated that using paraffin C38 results in a 280 % increase in power output, compared to a 144 % increase when paraffin C20 is utilized, relative to scenarios without any PCM. A PCM tank with a thickness of 1 cm yielded approximately a 70 % boost in power output. This enhancement increased to about 104 % with a 2 cm thick tank and reached around 214 % with a 3 cm thick tank.

Analyzing thermal‐moisture comfort and thermal protective performance of phase change materials dripped protective clothing

AbstractThe objective of the study was to alleviate the thermal‐moisture comfort (TMC) of phase change material (PCM) thermal protective clothing, while simultaneously enhancing thermal protective performance (TPP) by a drip molding process. Nine types of PCM dripped fabrics were prepared by the drip molding process and served as comfort layers of thermal protective clothing. The TMC and TPP of the fabric systems were measured. A new method was proposed to balance the TMC and TPP of thermal protective clothing. The results demonstrated that the drip molding process marginally weakened the TMC while substantially enhancing the TPP of fabric systems. But the TMCs of the PCM dripped fabrics were far larger than the PCM coated fabric. Specifically, an increase in droplet diameter led to a decline in TMC and an improvement in TPP, whereas an increase in droplet interval resulted in an enhancement in TMC and a decrease in TPP. The findings obtained in this study can be used to engineer fabric systems that provide better protection for heat stress and skin burns.

Passive domestic air-conditioning using PCM modules

Passive cooling systems have garnered much attention in recent years as a sustainable and cost-effective method of regulating indoor temperatures. Phase change materials (PCM) are a promising technology for such systems, as they can store and release large amounts of thermal energy during the phase transition process while maintaining the temperature in a very specific range. In this study, we investigated the performance of a passive cooling system using PCM modules and evaluated the effect of different variables on its cooling efficiency. Several tests were conducted, varying the ambient temperature, number of plates, and PCM type to determine the optimal conditions for the system. A PCM with a melting temperature of around 22 °C was used and was compared to ice. While ice showed a larger cooling effect, the advantage of the PCM emerged with elevated ambient temperatures. Compared to ice, and due to the smaller the temperature difference ΔT between the PCM melting temperature and the ambient temperature, the cooling effect of the PCM, lasted for a significantly longer time. Moreover, increasing the number of plates proved to elongate the cooling effect, due to increasing the overall thermal storage capacity of the system. Overall, our findings suggest that a passive cooling system using PCM technology can be an effective solution for regulating indoor temperatures. However, careful consideration must be given to the choice of PCM type and melting temperature, as well as the number of plates in the system, to optimize its performance.

Thermal energy storage using phase change material for solar thermal technologies: A sustainable and efficient approach

Over-exploitation of fossil-based energy sources is majorly responsible for greenhouse gas emissions which causes global warming and climate change. To mitigate these challenges renewable energy sources, especially solar thermal technologies, can play a decisive role. United Nations also proposes steps to attenuate the adverse effects of fossil-based energy and climate change through Sustainable Development Goals (SDG7 and SDG8). Solar thermal technologies have seen a huge capacity expansion around the globe in previous decades because of their inherent advantages. However, solar energy faces crucial limitations of fluctuating intensity and time-dependent availability. This decreases solar thermal system performance and makes solar thermal technologies time-dependent. To overcome these challenges, integrating phase change material (PCM) in solar thermal technologies makes a sustainable approach to enhance the efficacy, productivity, and utilization rate of solar thermal technologies. In this manuscript, the sustainable approach of integrating PCM in solar thermal technologies was reviewed. This includes literature on PCMs which covers classification, properties, importance, and limitation. Comprehensive data on the integration of PCM with solar thermal technologies such as solar water heating, solar desalination, solar cooking, solar dryers, solar PV/T, solar ponds, solar chimneys, and solar power plants were reported explicitly in terms of the type of PCM, efficiency and their productivity. In addition, the effect of PCMs integration in solar thermal technologies was analyzed in terms of mitigation of CO2 emissions and economic analysis at different locations around the World.

Photovoltaic panel cooling with new composite of phase change materials and hierarchical nanoparticles

In this research, the use of a new type of phase change materials (PCM) and hierarchical nanoparticles is discussed to improve the electrical and thermal efficiency of PV panels. TiO2/CuO hierarchical nanoparticles are synthesized by hydrothermal method, and PCMs containing nanoparticles (2.5–10%wt) are prepared, and then experiments are performed in indoor conditions under solar simulator light. The PV panel with a maximum nominal power of 30W is used. The new PCM is made from a mixture of lauryl alcohol and beeswax (LABW). A spiral heat exchanger is placed in the PCM container, in which the flow rate of cool water is variable (m˙ = 0.002–0.01 kg s−1). Firstly, the temperature and voltage-current changes of the PV panel with time are investigated without using PCMs as a reference case, and in steady-state conditions, the temperature and output power values are 67.34 °C and 22.33W. The use of LABW compared to pure beeswax leads to a significant decrease in the PV panel temperature and as a result, an increase in its electrical and thermal efficiency. Also, adding nanoparticles to PCMs from 2.5 % to 7.5 %wt due to the improvement of their thermal conductivity and increasing the heat storage rate of the PV panel leads to an increase in its electrical and thermal efficiency. There is no significant change to decrease the temperature and increase the production capacity of PV panels by increasing the percentage of nanoparticles from 7.5 % to 10%wt. The maximum production power, electrical and thermal efficiency of the PV panel at a flow rate of 0.01 kg s−1, 10%wt of nanoparticles, and a radiation intensity of 1000 W m−2 are 28.92 W, 12.55 %, and 76.67 %, respectively.

Thermal management characteristics of a novel cylindrical lithium-ion battery module using liquid cooling, phase change materials, and heat pipes

To improve the thermal performance of large cylindrical lithium-ion batteries at high discharge rates while considering economy, a novel battery thermal management system (BTMS) combining a cooling plate, U-shaped heat pipes, and phase-change material (PCM) is proposed for 21700-type batteries. The effects of variables such as the contact angle between a corrugated aluminum plate (CAP) and the battery, the coolant flow direction in the cooling plate, the type of PCM, and the coolant flow velocity on the thermal characteristics of the batteries in the BTMS are investigated, and the advantages of this coupling cooling strategy relative to a single active cooling or a single active and passive cooling combination strategy are discussed. The results indicate that a corrugated aluminum plate is beneficial for significantly improving the temperature uniformity of the batteries. A staggered flow-direction scheme of adjacent channels significantly improves the temperature uniformity relative to the other inlet flow modes. The thermal performance of the batteries in the BTMS using paraffin and expanded graphite (PA/ EG) is superior to that with pure paraffin or paraffin and copper foam (PCF), with temperature uniformity improved by 44.6 % and 16.0 %, respectively. Increasing the coolant flow velocity can decrease the maximum temperature of the batteries and significantly reduce the heat dissipation share of PCM, resulting in a decrease in the temperature uniformity of the batteries in the BTMS. Meanwhile, compared with pure liquid cooling or a combination of liquid cooling and heat pipe or PCM, the proposed coupling BTMS not only reduces the maximum temperature of the batteries and further improves the temperature uniformity, but also significantly reduces the operating energy consumption of the BTMS.

Battery thermal management system by employing different phase change materials with SWCNT nanoparticles to obtain better battery cooling performance

Maintaining a stable temperature within a battery is essential for optimizing the performance of battery thermal management systems. Phase change materials (PCMs) have demonstrated potential in achieving this stability. This study investigates the use of single-walled carbon nanotubes (SWCNTs) dispersed in three PCMs with varying fusion temperatures to regulate the temperature of a lithium-ion battery (LIB) during discharge, a common scenario in electric vehicles. A Computational Fluid Dynamics (CFD) approach was utilized to simulate the liquid-solid transition of the PCMs, incorporating buoyancy forces in the liquid phase surrounding the LIB. The study examined the effects of different C-rates (1, 2, and 3), SWCNT volume fractions (0, 2, and 4 %), and three types of PCMs (RT27, RT35, and RT58) across multiple simulation scenarios to evaluate their impacts on LIB temperature and PCM melting fraction. Results indicate that nano-enhanced PCMs, which exhibit superior convection effects in the liquid phase, significantly enhance battery cooling performance. Specifically, at a C-rate of 1, using a 4 % volume fraction of nanoparticles in the PCM reduces the battery temperature by an average of 4.138 K compared to cases without nanoparticles. Additionally, while nanoparticles are generally reported to have a minor effect on cooling and melting processes, this study reveals that considering the beneficial effects of SWCNTs and the physical properties of the selected PCMs, the cooling performance of LIBs improves by 4.69 percentage points for the scenario with a C-rate of 3, RT58, and ɸ = 0.02. In this particular case, the melting process is more pronounced in the top half of the battery, where the increased velocity magnitude of the melted region contributes to enhanced battery cooling.

Performance enhancement of evacuated U-tube solar collector integrated with phase change material

In this research, a numerical simulation was undertaken to assess the effectiveness of an Evacuated tube solar collector (ETSC). The study explored the efficacy of merging a parabolic trough solar collector (PTSC) and copper fins into the U-tube ETSC design. Two types of fins, namely annular fins and disk-shaped fins, were evaluated. Additionally, the study aimed to analyze the influence of operational and geometric parameters, such as the heat transfer fluid (HTF) mass flow rate and the U-tube bend radius, on the performance of the U-tube ETSC. Furthermore, a comparative examination was carried out to identify the most suitable type of phase change material (PCM) for the U-tube ETSC. Finally, a comparative analysis was conducted to assess the performance of the U-tube ETSC in comparison to that of the coaxial tubes ETSC. The results clearly demonstrated that the integration of an PTSC, PCM, and disk-shaped fins substantially improved the overall performance of the ETSC in comparison to the conventional solar collector. This improvement led to a remarkable increase in energy efficiency, with an impressive gain of 42.94 %. The ETSC displayed remarkable performance, particularly at lower HTF mass flow rates and a reduced U-tube bend radius, achieving an average HTF temperature of 430 K. Additionally, among the tested PCMs, RT 82 emerged as the most suitable choice, providing an energy gain of 9.27 % in comparison with the case without PCM.

Contemporary roof pattern for energy efficient buildings: Air conditioning cost alleviation, CO2 emission mitigation potential and acceptable payback period

Buildings account for a significant portion of global energy use and consumption. Buildings have substantial energy consumption due to the use of heating, ventilation, and cooling systems. It is evident that the use of insulation materials and phase change materials (PCMs) in the design of buildings can effectively reduce the cost of air conditioning by reducing external heat gains and losses. Additionally, the use of environmentally friendly, cost-effective, and natural materials can be beneficial from an environmental standpoint. This paper aims to evaluate the potential for cost savings in the air conditioning of various PCMs and insulation-stuffed building roof configurations. In that respect, four types of phase change materials (HS29, HS36, FS42, and FS30) and four insulation materials (Therma cork, sawdust, aerogel, and sheep wool) were selected. The thermophysical properties of PCMs (solid and liquid state), insulation materials, and building elements were determined experimentally as per ASTM D 5334 standards. Ten various building roof models (contemporary roof pattern) are studied with four various PCMs and four various insulations. In addition, novel building roof design integrated with PCM/insulation were analysed numerically, related to environmental conditions that refer to two different scenarios in India (hot dry and composite climates). It further analyses the reduction in greenhouse gas emissions associated with different roof configurations. The aforementioned PCM/insulation materials were stuffed in the void spaces of the contemporary roof pattern. Thermo-economic analysis of novel roof design with PCM/insulation materials on air-conditioning costs, carbon dioxide emissions and payback time are compared with conventional roofs (CR) and contemporary roof patterns (CRP). The thermo-economic analysis was carried out based on the number of degree-hours of heating and cooling to determine the building's annual energy usage. HS29 PCM stuffed roof pattern (HS29RP) saved the highest total energy cost savings of 11.89/14.71 $/m2/year when compared with conventional roof and 11.35/13.89 $/m2/year compared with contemporary roof pattern for Jabalpur/Kota climatic conditions. HS29 PCM stuffed roof pattern (HS29RP) exhibits the maximum carbon emission mitigation of 215.32/275.37 kg/kWh when compared with conventional roof and 204.95/259.57 kg/kWh for climatic conditions of Jabalpur/Kota. While considering shortest payback span, sawdust stuffed roof pattern shows the minimum payback period of 0.69 and 2.15 years when compared with conventional roof and contemporary roof pattern. The findings of this research offer significant contributions to the development of energy-efficient building envelopes applicable to a wider range of buildings, including those with and without air conditioning systems.

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 energy efficiency of PCM wall in winter with novel PCM-DLCB coupling design

In order to enhance the thermal performance of the phase change material (PCM) wall during winter, a novel PCM and double-layer capillary bundles (PCM-DLCB) coupling wall is proposed. The PCM-DLCB wall utilizes the capillary bundle near the outer surface to capture solar energy during sunny winter days. The heat is then transferred to the capillary bundle near the inner surface through a circulating pump, promoting the melting of the PCM. Optimization and long-term operation comparison research were conducted using numerical simulation to investigate the potential of the PCM-DLCB wall to improve energy efficiency during winter. Five structural parameters, including the type of PCM, the position of the capillary bundle, the position and thickness of the PCM layer, the spacing of the capillary bundles, and the flow velocity in the capillary bundle, were selected as variables for structural and operation optimization. The optimization target was the accumulated heat gain from the inner surface of the wall. The research results indicate that: (1) The most suitable PCM is RT-18HC; (2) Placing the PCM layer between the double-layer capillary bundle yields better results compared to other arrangements; (3) Optimal energy saving is achieved when the outer capillary bundle is positioned 6 mm away from the outer surface and the inner capillary bundle is positioned 8 mm away from the inner surface; (4) The optimal thickness of the PCM layer is 10 mm; (5) The optimal flow velocity in the capillary bundle is approximately 0.04 m/s. Furthermore, long-term operation results based on a typical hot summer and cold winter climate zone reveal that the optimized PCM-DLCB wall provides a 7.80 % increase in indoor heat gain compared to an ordinary PCM wall during winter, and an 18.4 % increase compared to a wall without PCM.

A review on thermal energy storage with phase change materials enhanced by metal foams

Due to the mismatch between energy demand and energy production, in the last years the study of latent thermal energy storage systems has been significantly growing. This work aims to provide an overview of the studies and the experiments carried out on thermal energy storage systems, that use phase change materials combined with metal foams. A histogram that shows how the number of works on these subjects has been increasing over the years is reported; consequently, a general survey on phase change materials is conducted, identifying the temperature ranges and the latent heat which are most used in thermal energy storage systems and defining the strengths and weaknesses of the various types of phase change materials. Furthermore, the paper illustrates the models and methods currently used to describe the phase transition of phase change materials in metal foams. Subsequently, how metal foams improve the desirable characteristics of phase change materials is described, and then it is represented in what percentage the different pore sizes (PPI) are used and what the most functional porosity is for individual works. Lastly, through the summary of the analyzed papers some specific articles are considered, in order to explain the state-of-the-art and to clarify some fundamental concepts.

Thermal regulation enhancement in multi-story office buildings: Integrating phase change materials into inter-floor void formers

Addressing the thermal loss from building envelopes is a crucial challenge and requires the exploration of various mitigation strategies. This study employs comprehensive 3D computational fluid dynamics simulations to investigate the incorporation of various bio-based Phase Change Materials (PCMs) including CrodaTherm (CT) 19, CT21, and CT24W, within inter-floor void formers between the roof-floor boundary in multi-story office buildings to optimize energy management during inactive periods in one of the adjacent units. Aside from the PCM type, the void former shape, its placement, and the combinations of PCMs and insulating layers are examined through heat flux and solid fraction plots as well as liquid fraction contours. Results highlight the exceptional performance of CT24W-integrated void formers, achieving a remarkable 36.74 % reduction in the 48-h average heat flux in comparison with the case without void formers, and offering lower heat flux values than the scenario with insulating layers for 89.38 h (endurance time). Based on the findings, with identical PCM volumes, the semi-ellipsoid PCM-integrated void former provides 11.07 % lower heat flux and 27.56 % longer endurance time compared to the one with a spherical shape. The results underscore PCM integration as a superior strategy over standalone insulation for managing thermal loss between apartment floors.

Phase Change Materials for Thermal Energy Storage: A Concise Review

Thermal energy and its storage systems play an extensive role in day-to-day life. They store renewable energy and are capable of recovering generated heat from different systems. Storage of thermal energy can be classified into three types: sensible, latent and sorption heat storages. Thermal heat storages use different types of materials based on their capacity of heat storage, stability of duration and thermal conductivity. Various phase change materials (PCMs) that are suitable for thermal storage are reported. Low conversion ability limits their effectiveness. We reviewed some of the traditional materials synthesized recently that are used for thermal energy storage (TES). Recently developed TES materials exhibit high thermal conductivity, reduced super cooling and multiple phase change temperatures. Nano-enhanced PCMs produced an increase in thermal conductivity up to 32% with a reduction in latent heat by 32%. At this juncture, MXenes with high performance and extraordinary properties (thermal, mechanical, etc.) are of special significance. MXenes displayed an increased thermal conductivity up to 16% and 94% efficiency. In view of their structure and adaptability to be used in thermal storage systems, an attempt was made to review their role also in thermal storage applications. It is observed that MXenes highly impact storage and efficiency. Apart from MXenes, various types of PCMs along with their thermal characteristics are presented.

On the effect of nanoparticles in different PCM configurations in the thermal performance of a packed bed energy storage system

When it comes to storing energy and releasing it when needed, packed bed storage systems are considered to be one of the most efficient systems available. This paper studies the thermal performance of the melting process in a packed bed system using spherical capsules through CFD modeling. The effective packed bed model was used to simulate the fluid flow in the packed bed and enthalpy porosity method was used to solve the phase change material (PCM) domain. The capsules were filled with three various types of phase change materials, while water was utilized as the heat transfer fluid (HTF). Due to the importance of configurations of materials in the packed beds, the effects of various layouts of them on the performance of the system were investigated. Moreover, Al2O3 nanoparticles as a cheap and easily available nanoparticles were added to the materials. Also, the change in inlet flow rate of the HTF was examined. According to the results, positioning the materials in decreasing order of melting temperature in the flow direction is able to decline the charging time of the system by about 1600 s and increase the charging efficiency by 6.8 %. The addition of Al2O3 nanoparticles was able to decrease the charging time by about 1900 s in the best case and increase the system's efficiency by about 7.5 %. Increasing the inlet flow rate of HTF from 2.5 × 10−5 to 5 × 10−5 (1.5–3 Lit/min) reduced the charging time about 1800 s.

Enhancing Building Thermal Inertia: Impact of Surface-to-Volume Ratio on Multi-Layered PCM-Integrated Brick Walls

Abstract In this paper, a numerical study is conducted to investigate the effect of using Phase Change Materials (PCMs) in building bricks to improve the thermal inertia of buildings in hot and dry regions. A numerical model is developed to simulate the heat transfer in a brick with cylindrical holes filled with PCM. The effects of the number, type, and arrangement of PCMs on the thermal performance of the brick are investigated. The results show that the use of PCMs can significantly reduce the heat flux through the brick. The optimal number of PCMs is found to be three layers. The optimal type of PCM for the first layer is n-Eicosane, for the second layer is Paraffin Wax, and for the third layer is n-Octadecane. The enhanced brick configuration, with specific PCM arrangements, reduced total heat flux by up to 71.53% in the simulation period, compared to a brick without PCM.