Integration Of Phase Change Materials Research Articles

Reviewing the Potential of Phase Change Materials in Concrete Pavements for Anti-Freezing Capabilities and Urban Heat Island Mitigation

This study provides an overview of how phase change materials (PCMs) can improve the resistance of concrete pavement to freeze–thaw cycles and mitigate the urban heat island (UHI) effect. The investigation covers different types of PCMs and methods for integrating them into concrete pavement, as well as the mechanical properties and compressive strength of concrete pavement when employing various PCMs. Prior studies have identified porous aggregates, microencapsulation, and pipelines containing liquid PCM as common approaches for PCM integration. Researchers have observed that the utilization of PCMs in concrete pavement yields favorable thermal properties, suggesting the potential for anti-freezing and UHI mitigation applications. However, the choice of PCM materials should be informed by local climate conditions.

Innovative Integration of Phase Change Materials and Conceptional Design of Test Cases – New Products for the Building Envelope

The building sector contributes to a great part of energy consumption and has a major impact on climate in Europe. Development of climate-friendly and energy-efficient products is required to reach low and net-zero energy buildings and to facilitate the energy transition. The building envelope is critical in defining the demand for space heating and cooling as well as ensuring thermal comfort and indoor environmental quality through proper ventilation. This paper presents the conceptual test cases integrating phase change materials (PCMs) in the building envelope. PCM absorbs, stores, and releases the heat energy in a controlled manner taking advantage of the temperature difference between night and day. Hence PCM can support the thermal management of the building by minimizing unwanted heat gains and losses while integrated into walls or support the energy efficiency of ventilation while supplying fresh air. Smart ventilated heat harvesting windows and multifunctional sandwich panels are developed within the EU-funded iclimabuilt project. Additionally, commercial air-guided PCM storages are presented as ready-to-install products for decentralized ventilation and heat recovery systems.

Energy and exergy analysis with cost-efficiency comparison of modified phase change material (PCM) integrated with solar panel thermal system

This study investigates the efficiency and cost-effectiveness of integrating Phase Change Materials (PCMs) into solar panels to optimize power output and power conversion efficiency under varying temperature conditions. By applying PCMs, temperature fluctuations can be reduced, maintaining solar panels at an optimal temperature for power generation. The research employs modeling and simulation techniques, focusing on energy and exergy analysis of solar energy storage systems based on pure and modified PCMs such as Paraffin wax, Sodium acetate trihydrate, Sodium sulfate decahydrate, etc. Temperature and light intensity data are collected in the Wangchan district, Rayong province, using a light intensity sensor and a thermocouple. The study analyzes each layer of the solar panel, employing numerical methods and matrix solutions to solve the system of non-algebraic equations, yielding temperature values for each component layer. The thermodynamic properties of the modified PCMs are calculated theoretically, and their cost-efficiency is analyzed by comparing the solar panel’s increased power area density generation after applying specific PCMs to the cost of the PCM. The simulation results demonstrate that the solar panel integrated with PCM generates up to 11.1% more power than a regular solar panel, assuming negligible heat loss from the sides of the solar panel and an average temperature during the melting and solidification processes for the PCMs. Moreover, the best cost-efficiency of the modified PCM is achieved, with an increase of up to 637.7%, using a combination of paraffin wax and polyethylene glycol.

Revolutionizing Automotive Cooling: A Comprehensive Review on Enhancing Radiator Performance through Nanofluid-Based Heat Transfer Augmentation and Pipeline Integration of Phase Change Materials

Abstract: This review explores cutting-edge advancements in automotive cooling systems, specifically focusing on enhancing radiator performance through a dual approach: the utilization of nanofluids for improved heat transfer and the incorporation of phase change materials (PCMs) within radiator pipelines. Nanofluids, engineered colloidal suspensions of nanoparticles in traditional coolants, exhibit enhanced thermal conductivity, leading to improved heat dissipation. The paper provides an overview of various nanofluid synthesis methods and reviews experimental studies showcasing their efficacy in augmenting thermal performance within automotive radiators. In parallel, the integration of PCMs into radiator pipelines introduces a novel dimension to heat management. Phase change materials, with their ability to store and release latent heat during phase transitions, contribute to temperature regulation and energy efficiency. The review explores different types of PCMs, their selection criteria, and summarizes experimental findings related to their incorporation in automotive cooling systems. A significant portion of the paper delves into the synergies and challenges associated with combining nanofluid-based heat transfer enhancement and PCM integration. The discussion underscores the potential for a holistic approach to radiator design, leveraging the complementary benefits of both nanofluids and PCMs. The findings presented in this review offer insights into the evol

An investigation into enhancing energy storage capacity of solar ponds integrated with nanoparticles through PCM coupling and RSM optimization

Solar energy is a promising renewable resource for meeting energy demands, with solar pond systems offering efficient thermal energy storage. Integrating Phase Change Materials (PCMs) and nanoparticles into solar ponds has shown potential to enhance energy storage capacity and thermal performance. This study focuses on optimizing the energy storage capacity of a solar pond system by employing Response Surface Methodology (RSM) to analyze the combined effects of PCM and nanoparticles integration. As input parameters for the optimization process, variables such as pond depth, salinity gradient, insulating materials, and solar radiation were taken into account. To maximize energy collecting and storage efficiency, the goal was to determine the ideal combination of these characteristics. To optimize the temperature distribution, Taguchi's L13 orthogonal array method and ANOVA were used. The results of the study indicate that the solar pond configurations with AgTiO2/Paraffin wax and CNT/Paraffin wax exhibited significantly higher energy storage capacities compared to the plain paraffin wax solar pond. Specifically, the AgTiO2/Paraffin wax solar pond showed an energy storage capacity increase of 7.48⁒, while the CNT/Paraffin wax solar pond exhibited an increase of 3.82⁒, in comparison to the plain paraffin wax solar pond. These findings highlight the substantial improvements in energy storage achieved by incorporating nanoparticles (AgTiO2 and CNT) into the paraffin wax as phase change materials within the solar pond system. The optimization study's findings showed that solar pond system performance has significantly improved.

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.

Optimal evaluation of photovoltaic-thermal solar collectors cooling using a half-tube of different diameters and lengths

Photovoltaic Thermal Solar Collectors (PVTs) combine the advantages of photovoltaic (PV) and solar thermal collectors to produce electricity and heat simultaneously. This study proposes a numerical model to investigate the effectiveness of using half-circular tubes to improve thermal conductivity and increase the interaction area between PV panels and tubes. This enhances heat transfer from the PV panels to the working fluid (water) circulating through the thermal absorber. Additionally, the integration of phase change material (PCM) is explored to further boost thermal conductivity and generate hot water. The research focuses on modeling the cooling of solar PV panels using copper half-tubes. The PV panels measure 870 × 665 × 3 mm and generate a power output of 100 W. The study examines the impact of key variables such as tube diameter (three standard sizes: 10, 12, and 15 mm) and fluid flow rate (0.008 to 0.04 kg/s). Solar radiation equations are incorporated, and the finite volume approach, implemented in the ANSYS 19.0 software's CFX modeling framework, is used as the underlying methodology. The investigation culminates in an optimization process to determine the optimal operating conditions for the PV system. The results show that the highest electrical efficiency (13.15%) is achieved at a flow rate of 0.04 kg/s for 15 mm diameter tubes and 7 tubes in total. The peak thermal efficiency (74.28%) is observed under the same conditions. In conclusion, this study contributes to the understanding of enhancing PV/T system performance through innovative thermal management strategies and provides valuable optimization recommendations for achieving improved electrical and thermal efficiencies.

Comparative study of different phase change materials on the thermal performance of photovoltaic cells in Iraq's climate conditions

The incident solar energy that impinges upon the photovoltaic cells undergoes a conversion process, resulting in the generation of electrical energy and conversion of absorbed energy into heat. This increase in temperature adversely affects the performance of the panel, leading to a decrease in its overall efficiency. This study examines the properties and performance of phase change materials, specifically paraffin wax, natural beeswax, and a combination of paraffin wax and beeswax, in comparison to a solar panel lacking any phase change substance. The experiment was conducted in the climatic conditions of Iraq, namely in the city of Hawija, located southwest of Kirkuk, during the summer of 2022. The prevailing environmental temperature throughout this period averaged 44 °C. The experiment involved comparing plate temperature, electrical power, and electrical efficiency. The results indicated that all the materials caused a decrease in the temperature of the board at the beginning of the experiment and for a short duration. Nevertheless, as the phase change material (PCM) undergoes melting, the dissipation of heat becomes unfeasible, resulting in a gradual increase in temperature. It was observed that there was a rise in temperature during the afternoon hours. According to the recorded data, the use of beeswax resulted in a decrease in temperature by 4 °C in comparison to the reference plate that did not incorporate phase change materials (PCM). Additionally, the efficiency of the photovoltaic (PV) system increased by 1% when compared to the PV Compared with PV (reference). The efficiency of the solar panel with beeswax ranged from 13% to 14%. According to the findings, the integration of phase-change materials with solar panels has been observed to effectively lower the temperature of the panels, hence enhancing their overall efficiency. Consequently, this approach represents a viable and advantageous choice.

Enhancing photovoltaic performance through solar radiation splitting: A beam splitter-assisted hybrid approach with 2-D tracking and PCM integration

Solar energy is an abundant and environmentally friendly power source; however, its conversion efficiency is limited by the mismatch between the response of photovoltaic (PV) and the solar spectrum. This paper proposes a novel hybrid system that splits solar radiation into visible and thermal components using a beam splitter. Through experimental and theoretical analyses, the study explores the integration of a phase change material (PCM) packed bed with a PV cell as a hybrid system to optimize energy conversion. The experiment is carried out using a 2D tracker. The concentration ratio, determined based on the maximum concentration ratio (MCR) supported by the PV cell, is established as the optimum point. For Silicon PV, the maximum concentration ratios are determined to be 8 and 16 sun for the cases of using and not using the beam splitter, respectively. The ratios of thermal and visible energy, measured at a wavelength of 700 nm, are observed to be 60.66 % and 39.33 % respectively. Under MCR conditions, in the PV system alone, the generated power reaches approximately 850 W/m2, while in the hybrid splitting configuration, it increases to around 1200 W/m2, resulting in a 43 % increase in the system's net power when employing the beam splitter. Furthermore, the study reveals that the utilization factor remains constant at 0.13 across all irradiation ranges for PV-alone systems. In contrast, for the PV/PCM hybrid splitting system, the utilization factor exhibits an increasing trend with higher solar irradiation intensities, reaching values of 0.31, 0.41, and 0.46 for irradiation ranges of 900, 950, and 1000 W/m2, respectively. The findings of this study suggest the potential of using a beam splitter in combination with a 2-D tracker and PCM-packed bed to increase PV efficiency. The proposed configuration demonstrates a substantial enhancement in total net power output, offering a promising avenue for advancing solar energy conversion technologies. Adding PCM to the system has proven to be beneficial, as it addresses the fluctuations in solar radiation and may enhance the total system efficiency.

Effects of different heat transfer enhancers in PCM-based latent thermal energy storage for hydrogen storage in activated carbon bottle

This study presents a numerical simulation of a packed bed reactor filled with activated carbon for hydrogen storage, incorporating phase change material (PCM) with various heat transfer enhancers. The simulations were performed using the Fluent ANSYS. The main goal is to explore the use of PCM as a heat manager (reactor coolant) and optimize its performance by investigating the effects of various enhancers, including nanoparticles (NP), metal foam (MF), and fins, on the melting efficiency of PCM in activated carbon beds. Outcomes showed that the hydrogen adsorption capacity of 25 mmol/g was found to be independent of the type of PCM enhancer used in the system. The results showed that the MF provided the best cooling performance of the activated carbon bed, with a surface heat flux of 2750 W/m2 and a surface heat transfer coefficient of 410 W/m2K, while fins provided the highest melting rate of the PCM. In the presence of fins, metal foam, and nanoparticles, the fusion rate of PCM has been enhanced by 64, 32, and 8%, respectively, compared to pure PCM. These findings provide valuable insights into the design of packed bed reactors for hydrogen storage and can be used to optimize the thermal performance of the system. Based on the obtained findings, it is recommended that future studies on H2 storage in solid beds should be focused on the optimization of fins, metal foams, use of other nanoparticles, integration of composite PCMs, adoption of chemically modified or nanoporous carbon beds, and possibly the employment of hybrid enhancers.

Dynamic heat-transfer mechanism and performance analysis of an integrated Trombe wall with radiant cooling for natural cooling energy harvesting and air-conditioning

Natural cooling energy and high-efficient radiant cooling techniques are essential to mitigate energy resources shortage crisis, breakthrough on traditional convective air-conditioning systems in isolation between indoor and outdoor environment with high indoor air quality. In this paper, a polyethylene aerogel (PEA) and phase change material (PCM) integrated novel Trombe wall was proposed, involving natural cooling energy harvesting, cooling energy storage, indoor ventilation and radiant cooling. A two-dimensional unsteady numerical model based on surface-to surface (S2S) radiation model and effective specific heat capacity method was developed in the commercial software Ansys Fluent to evaluate the cooling performance and dynamic heat-transfer mechanism of the novel Trombe wall. Subsequently, climate-responsive operation strategies on ventilation modes were proposed to maximize natural cooling energy utilization and fresh air supply. Parametrical and comparative studies were conducted on optimal structural design and robust operation. Our results showed that, with the novel design and advanced operation strategies, passive cooling capacity of 0.64 kWh/m2·day can be provided, together with fresh air supply of 2705.2 kg/day (1.4 m2 Trombe wall), corresponding to air change rate per hour (ACH) of 1.15. In terms of active cooling system, the integration of PEA and PCM can effectively prevent moisture condensation and shift peak cooling load. Hence, radiant cooling capacity of 0.99 kWh/m2·day and radiant cooling ratio of 47 % can be achieved by the novel Trombe wall, with electricity consumption only at valley period. Moreover, economic saving of 55.0 CNY/day and decarbonization potential of 23.8 kg CO2,e/day can be achieved when the novel Trombe wall is integrated into a typical office building in subtropical climate Guangzhou. This study provides a novel structural design and optimal operation strategies on a Trombe wall, together with guidelines on techno-economic-environmental performance improvement, promoting effective natural cooling energy utilization and energy-flexible/efficient radiant cooling for decarbonization of buildings in cooling-dominant regions.

An approach to improve the efficiency of cooling enhancement of a thermoelectric refrigerator through the use of phase‐change materials

AbstractIn this study, a technique is suggested to enhance the temperature difference for cooling and energy efficiency of thermoelectric cooler (TEC) used in cooled detectors when subjected to high current conditions. Embedding a structure for storing heat during phase change is the basis of this method at the heat sink. A simulation model was created for a common two‐stage series TEC with an asymmetrical design, which is coupled with a structure for storing heat through phase change. The research examined how phase transition heat storage impacts the coefficient of performance (COP) and refrigeration temperature difference across various phase‐change substances, heat transfer coefficients at the hot end, currents, and the height of the phase‐change material (PCM). The findings suggest that the suggested approach of combining PCM with TEC can efficiently lower the cold end temperature of TEC by a maximum of 20 K, enhance the temperature gap by a maximum of 16 K, and preserve the consistency of the optimized quantity across various hot end heat transfer coefficients. During the phase‐change process of PCMs, the COP of TECs integrated with PCM is found to increase by an average of 2%–3% compared to TECs without PCM integration. Under the maximum current operating condition, the cryogenic temperature can be optimized to a minimum of 238 K. In summary, the proposed method of integrating phase‐change heat storage with TECs provides a promising solution for improving their cooling performance and energy efficiency in cooled detectors under high current conditions. Additional investigation can be conducted to explore the practical application of this approach and enhance the design parameters for various uses.

A Systematic Analysis of Phase Change Material and Optically Advanced Roof Coatings Integration for Athenian Climatic Conditions

Energy retrofit solutions that concern a building’s roof structure play a significant role in the enhancement of a building’s thermal behaviour. This study investigates the integration of phase change materials (PCMs) with cool coatings (CCs) or thermochromic coatings (TCCs), namely, a PCM roof, a PCM-CC roof, and a PCM-TCC roof, as alternative and novel tactics for the simultaneous control of solar heat transfer and solar heat reflection. An energy simulation analysis with the DesignBuilder tool is conducted for a one-story residence and the climatic conditions of Athens. The simulation results indicate that, compared to the existing concrete roof construction, the PCM roof, PCM-CC, and PCM-TCC roof systems demonstrate energy savings that reach up to 13.55%, 16.04%, and 21.70%, respectively. The systematic analysis reveals that the increase in PCM’s thickness leads to an increase in the total electricity savings of the buildings, but in the case of PCM-CC and PCM-TCC roof systems, they merely effect the cooling thermal loads. The mean phase transition temperature that favours the cumulative electricity savings is 28 °C in the case of PCM and PCM-TCC roof systems and 35 °C in the case of PCM-CC roof systems. The methodology of this study allows the design of efficient, integrated roof systems with advanced thermal and optical properties as energy retrofit solutions for Mediterranean climatic conditions.

Enhancing solar façade thermal performance with PCM spheres: A CFD investigation

To improve building energy efficiency and address thermal storage challenges during periods without a heat source, such as cloudy weather or night-time, a range of solutions is required. Innovative technologies and sustainable practices are essential for combating climate change and reducing carbon emissions. This study primarily focuses on Thermal Energy Storage (TES) systems, specifically those using Phase Change Materials (PCMs), to increase energy efficiency for Transpired Solar Collectors used in buildings applications. During the last 30 years Transpired Solar Collectors (TSC) have been extensively investigated. However, a primary concern still exists regarding thermal storage when the heat source is unavailable, such as during periods of cloudy weather or at night. Thus, a Thermal Energy Storage (TES) system coupled with the TSC is a potential solution. In this study we are investigating using numerical simulation the arrangement of encapsulation for TES, integrating phase change materials (PCM) in spherical elements when compared with plate encapsulation elements. The model reproduces a part of a real scale thermal energy storage inserted in a Double Skin TSC. The model consists of a Plexiglas duct in which four different arrangements for the spherical encapsulated PCM were studied. For each of the arrangements the heat transfer between the TES elements and the air passing through the collector was analyzed. The primary finding of the study indicates that the hexagonal arrangement offers better passive airflow control, thus enhancing the heat transfer up to 12.3% compared to the rectangular arrangements

Numerical investigation of a cylindrical lithium-ion battery pack with integrated phase change material and coolant circulating channels

The integration of passive cooling (PCM) and active cooling as a battery thermal management system integrate the advantages of attaining a low maximum cell temperature and maintaining temperature uniformity in the battery module. However, there have been few studies that incorporate rectangular liquid channels in a PCM battery module composed of a high number of cylindrical cells. In this work, a new hybrid cooling system comprised of thirty cylindrical lithium-ion batteries (18650) combined with phase change material and a cooling channel was developed. The novelty of the study lies in the fact that (i) the battery module is designed to have a single inlet and outlet and is bifurcated at the inlet side to improve the symmetrical cooling of the entire battery module. (ii) This symmetrical cooling enhances temperature uniformity among battery cells, lowers maximum cell temperature, and delays PCM melting, allowing the PCM to absorb more heat from the batteries. (iii) In comparison to other complex hybrid cooling systems, the channels in this module may be easily manufactured, lowering the cost of battery module production. Insights into the influence of liquid channels can be best analyzed by extracting temperature and melted fraction data of phase change material. The proposed cooling system was shown to be capable of keeping the batteries' temperature below the optimal operating temperature at four different discharge rates (1C, 2C, 3C, and 4C). The proposed hybrid cooling system demonstrated to operate under harsh operating circumstances while yet keeping the battery at a safe temperature. At a mass flow rate of 0.001 kg/s and an inlet temperature of 30 °C, a maximum temperature and maximum temperature difference of 37 °C and 1.69 °C, respectively, were obtained, which are below the optimum temperature of 40 °C and a temperature difference of 5 °C. A maximum temperature and maximum temperature difference of 37 °C and 1.69 °C respectively were obtained at a water inlet temperature of 30 °C, making it the preferred inlet temperature.

Effect of blending of medium-temperature phase change material on the bitumen storage heat

This study aims to investigate the feasibility of using D-Mannitol as a phase-change material (PCM) to increase the energy storage capacity and improve the thermomechanical characteristics of the modified bitumen. D-mannitol (Dm) was incorporated into Bitumen (Bm) using a high-speed shearing method. The results showed that the integration of PCM enhanced the physical characteristics of the basic bitumen, with the modified bitumen having a melting point close to that of D-mannitol (Tm = 164 °C). The D-mannitol was found to crystallize during cooling, indicating that it can store or release heat in the latent form. The specific heat capacity of the modified bitumen was proven to increase gradually as the PCM content (2, 4, and 8 wt%) increased. The maximum temperature regulation effect of the modified bitumen was observed when the PCM content reached 8 wt%, resulting in a temperature reduction of up to 9 °C. This study provides a basis for the utilization of D-Mannitol as a form of energy storage in bitumen-based pavement applications.

Advancements in Household Refrigeration: Evaluating Cooling Efficiency and Sustainability through Innovative Technologies

Abstract: Household refrigeration technology has undergone significant advancements in recent years, driven by the need for energy efficiency, environmental sustainability, and improved cooling performance. This comprehensive study delves into various aspects of household refrigerators, including single condenser systems, double condenser configurations, and the integration of Phase Change Materials (PCMs) on the condenser surface. In Case 1, we conducted experiments to determine the cooling capacity of a standard household refrigerator equipped with a single condenser. Precise measurements and data analysis allowed us to evaluate its cooling efficiency, a crucial factor in preserving perishable items and assessing energy consumption. Case 2 extended our investigation to refrigerators with double condenser units, aiming to understand their impact on cooling performance. By comparing results with Case 1, we evaluated the potential advantages of this configuration in terms of cooling capacity and energy efficiency

A Comprehensive Study on a Household Refrigerator with a PCM-Enhanced Condenser: Experimental and Numerical Approaches: A Review

Abstract: Household refrigeration technology plays a pivotal role in our daily lives, ensuring the preservation of perishable goods and contributing to energy efficiency. This study presents a comprehensive investigation into improving the efficiency and performance of household refrigerators by integrating Phase Change Materials (PCMs) into the condenser system. We employ a combination of experimental and numerical approaches to evaluate the impact of PCM integration on refrigeration systems and explore its potential for broader applications. In the data presentation phase, we utilize graphs, tables, and figures to present experimental and numerical results clearly. These visual aids enhance our ability to convey complex data and insights to our audience. The analysis and discussion delve into the findings from both experimental and numerical approaches. Our results indicate that PCM-enhanced condensers can significantly improve the energy efficiency and cooling performance of household refrigerators. We discuss the implications of these findings on the broader field of household refrigeration technology and highlight the potential for reduced energy consumption and greenhouse gas emissions. The conclusion and future work provide a concise summary of our key findings and contributions to the field. We underscore the significance of our research in advancing the state of household refrigeration technology and identify avenues for future research, including further enhancements in PCM integration and its application in various refrigeration systems. To ensure the credibility of our research, we plan to subject our methodology, results, and conclusions to peer review by experts in the field. Additionally, we emphasize the importance of experimental validation to confirm the consistency and reliability of our findings. Throughout the research process, ethical considerations remain a paramount concern. We pledge to adhere to ethical standards, safety protocols, and environmental regulations to ensure the responsible conduct of our research. In summary, our study embarks on a promising exploration of PCM-enhanced condensers in household refrigeration technology. By combining experimental and numerical approaches, we aim to contribute valuable insights that not only enhance the efficiency of household refrigerators but also offer a sustainable solution for a greener future. This research endeavors to bridge the gap between theoretical knowledge and practical implementation, paving the way for innovative advancements in refrigeration technology.

A novel method to evaluate phase change materials' impact on buildings' energy, economic, and environmental performance via controlled natural ventilation

The construction industry consumes a significant portion of global energy, with space conditioning in buildings accounting for a substantial 34% of energy usage. Notably, the energy consumption of a building is significantly influenced by its envelope. Researchers widely acknowledge that incorporating phase change materials (PCM) into the building envelope is a promising way to enhance energy efficiency and mitigate CO2 emissions in the building sector, owing to their high latent heat capacity. However, PCM must be completely charged after each cycle to exploit its full potential. Natural ventilation is a viable technique to facilitate the charging and discharging cycle of PCM within a 24-h period. To this end, the present study utilized EnergyPlus simulations to optimize the cooling energy savings of a residential building incorporating PCM into its envelope for PCM melting temperatures, considering various ventilation strategies across 45 cities in 15 climate zones worldwide. In order to evaluate the latent heat utilization of PCM and its improvement facilitated by natural ventilation, two novel indicators, namely HS and HR, were formulated to represent the heat stored and released by PCM during a 24-h cycle, respectively. In addition, following an economic analysis of PCM integration, a comprehensive environmental evaluation was carried out, which included the carbon intensities (CI) of all fuel sources contributing to power generation. The study's findings reveal substantial energy savings across all climate zones when controlled natural ventilation is coupled with PCM, and the newly proposed indicators precisely quantify the performance of PCM in all scenarios evaluated. In the arid climate zone (A), combining PCM and natural ventilation enhances energy savings, albeit to a similar extent as using ventilation alone. However, the integration of PCM with temperature-controlled ventilation yields striking energy reductions of up to 72.8%, 85.3%, and 61% in arid (B), warm temperate (C), and snow (D) climate zones, respectively. The cost-benefit analysis reveals a minimal return period of as short as five years in climate zone C. In the same climate zone C, the in-depth environmental analysis reveals a maximal reduction of 42,004 CO2-e kg/year in carbon emissions. In conclusion, this research study demonstrated that integrating PCM with controlled natural ventilation offers a practical, sustainable, and cost-effective solution with eco-friendly and energy-efficient outcomes.

Direct-expansion solar-assisted heat pump coupled with crystallisation-controlled supercooled PCM for shifting building electricity demand

This paper proposes a novel approach for improving the performance of a direct-expansion solar-assisted heat pump (DX-SAHP) system by integrating a crystallisation controllable phase change material (PCM) and building energy demand shifting strategy. The proposed system aims to reduce buildings' energy consumption while utilizing solar energy efficiently. Sodium acetate trihydrate (SAT) as the crystallisation controllable supercooled PCM has a promising feature of releasing the stored latent heat when it is externally triggered, allowing the user to control the stored heat whenever needed. In the study, the PCM can store the thermal energy generated by the DX-SAHP during peak solar hours in an efficient way. This stored energy can be released when solar energy is unavailable, but the heating is requested. This approach not only reduces the load on the heat pump system but also makes efficient use of the stored thermal energy by crystallisation controllable PCM. A detailed controlling methodology of the system is given, and heating output is controlled considering the level of solar irradiance. The proposed system was modelled and simulated using MATLAB, and the results show that the integration of crystallisation controllable PCM and building demand shifting strategy can significantly reduce the energy consumption of the buildings. On the low solar radiation day, the COP improvement compared to the air source heat pump system was found 9.4%, this improvement value can reach 77% on high solar radiation days. The system can also effectively utilize solar energy and reduce the overall carbon footprint of buildings.