Incorporation Of Phase Change Materials Research Articles

Computational Modeling of an Earth-Air Heat Exchanger Integrated with Phase Change Materials: A Case Study Performed for the Viamão City, Rio Grande do Sul State, Brazil

The earth-air heat exchanger (EAHE) is a sustainable option that allows the electrical energy consumption reduction in buildings. The objective of this study is to evaluate the influence of the incorporation of the thermal energy storage principle based on phase change materials (PCM) into the EAHE on its thermal potential. For this, a three-dimensional numerical model of the PCM coupled to the EAHE (EAHE-PCM) was developed based on the effective heat capacity method and adapted to the climatic conditions and soil characteristics of the Viamão city, Rio Grande do Sul State, Brazil. It was found that for a duct diameter and length of 0.11 m and 25.77 m, the incorporation of PCM to EAHE improved by 8.90% and 3.97% in the average annual thermal potential of heating and cooling, respectively. In addition, the average monthly thermal potential increased 19.70% (heating) and 8.48%(cooling), for the months of May and December, respectively, when the PCM was integrated into the system.

Seismic and energy upgrading of existing buildings—full‐scale testing of retrofitted masonry‐infilled RC frames

AbstractTaking into consideration the seismic vulnerability and the poor energy performance of the European building stock, and the increasing socio‐economic and environmental need for integrating seismic upgrading with energy efficiency improvement, an experimental study involving the lateral load testing of full‐scale one‐story one‐bay masonry infilled RC frames and load‐bearing masonry walls was carried out in the framework of the SupERB research project aiming to investigate the efficiency of integrated seismic and energy upgrading systems. The integrated approach is based on the use of textile reinforced mortar (TRM) overlays combined either with traditional thermal insulation (extruded polystyrene, XPS) or with thermally efficient mortar incorporating phase change material (PCMs). The proposed integrated approach can be applied on the exterior face of the structure, so as to facilitate its application in real structures in the easiest possible way and with minimum disturbance to the inhabitants of the buildings. In this paper, only the structural performance of masonry‐infilled RC frames retrofitted with the proposed integrated approach is presented, while the energy benefits will be presented in a separate paper. Thus, in this paper, the structural performance of an integrated seismic and energy upgrading approach was assessed through five full‐scale one‐story one‐bay masonry infilled RC frames that were retrofitted with different schemes of TRM combined with thermal insulation materials subjected to in‐plane displacement‐controlled cyclic loading. The following parameters were investigated experimentally: the number of TRM overlays (one or two layers of TRM combined with thermal insulation), the use of thermally efficient PCM‐enhanced TRM layer in contrast to the use of conventional XPS insulation, and different retrofitting configurations (placement of the TRM in a sandwich form over and/or under the novel or the traditional insulation). From the results obtained in this study, it can be concluded that all energy and seismic upgrading systems examined have a positive impact on the response of the structural system to cyclic loading, with the ones with two layers of TRM having a better performance compared to the ones with one layer of TRM and all of them a better performance than the control specimen. The use of two layers of TRM cancels the drawback of infilled frames, which at very small drifts they reach their maximum capacity and after that they rapidly fall to the capacity of the bare frame, providing capacities above 80% of their peak capacity for drifts up to 2%. In all the tests the TRM whether it was combined with XPS or included PCMs contributed to a better distribution of the cracks in the infill and delayed premature brittle failures. The presence of the TRM had also the advantage that it remained intact throughout the tests preventing the fall of debris out of the plane of the infilled frame, both in the retrofitted and unretrofitted sides.

Phase change materials incorporation into 3D printed geopolymer cement: A sustainable approach to enhance the comfort and energy efficiency of buildings

The advent of 3D printing has revolutionized conventional construction, offering cost-effective and fast construction of complex structures. Nevertheless, there remain challenges to be addressed regarding the effective integration of functional additives into 3D printing construction materials. Herein, we present a straightforward and environmentally friendly approach to promote sustainable buildings while reducing energy consumption. This is achieved by integrating Macroencapsulated Phase Change Materials (MEPCM) into a 3D printable geopolymer paste (GPP) derived from fly ashes. The research followed a systematic methodology, encompassing the assessment of fresh and hardened properties of geopolymer pastes with varying amounts of MEPCM, analyzing their thermal properties, and investigating the thermal performance by printing miniature houses without and with 20 vol% MEPCM. Notably, MEPCM demonstrated its dual functionality as a thermal energy management component and a viscosity modifier for 3D printable geopolymer paste. Overall, this study paves an innovative path toward sustainable construction, highlighting the significance of energy efficiency and waste reduction.

Experimental study of vapor compression refrigeration system enhanced via tubular heat exchanger incorporating single/dual phase change materials

Vapor compression refrigeration (VCR) systems operating in hot climates suffer from high condenser temperatures that reduce their performance. One interesting approach being investigated to improve VCR performance is incorporating phase change materials (PCMs) into VCR systems that have not yet been expanded experimentally. So, this work experimentally studies the effect of using tubular PCM heat exchanger to cool the VCR condenser. The impact of two PCMs types suitable for warm climate conditions: SP24 and SP26, and combination of them on the VCR energy and exergy performance is investigated for two inlet ambient air temperatures. The impact on the exit air and PCMs temperatures, and VCR unit's pressure-enthalpy curve, VCR coefficient of performance, and power consumption is also examined. The results show that PCM-equipped systems significantly enhance the VCR exergy efficiency and coefficient of performance, especially at higher ambient temperature. Compared to the system without PCM, the power consumption can be reduced by up to 10.4% with PCM, while the exergy efficiency and coefficient of performance can be improved by 13.7% and 13.4%, respectively. While PCM SP24 provides the best performance, PCM SP26 has longer effective cooling period. A combination of SP24 and SP26 balances the performance and effective cooling period.

Perspective on the Development of Energy Storage Technology Using Phase Change Materials in the Construction Industry: A Review

The construction industry is responsible for high energetic consumption, especially associated with buildings’ heating and cooling needs. This issue has attracted the attention of the scientific community, governments and authorities from all over the world, especially in the European Union, motivated by recent international conflicts which forced the countries to rethink their energy policies. Over the years, energy consumption has been based on non-renewable energy sources such as natural gas, oil and coal. Nowadays, it is urgent to implement solutions that aim to minimize these high energetic consumptions and act based on clean and renewable energy sources. In recent years, phase change materials (PCM) have become an area of high interest and development, since they allow to minimize the energy consumption in buildings, based in solar energy, due to their thermal storage capacity. The main objective of this work consists of a perspective of the evolution of the development and application of thermal storage technology through the incorporation of PCM in the construction sector, focusing on the last 10 years of research, showing the most recent developments of its application in construction materials, such as mortars, concrete, incorporation in porous aggregates, naturally based materials, carbon-based materials, boards, blocks and solar thermal systems.

Thermal energy saving and physico-mechanical properties of foam concrete incorporating form-stabilized basalt powder/capric acid based composite phase change material

The incorporation of phase change materials (PCM) in construction materials for the purpose of thermal energy storage (TES) can prevent temperature fluctuations and enable the conservation of thermal energy in buildings. Accordingly, this study aims to create a novel, environmentally friendly foam concrete incorporating a composite PCM composed of capric acid saturated waste basalt powder. Basalt powder, a byproduct of the grinding or crushing of basalt volcanic rock, was selected as a carrier material due to its high porosity resulting from its lightweight and porous nature. This allowed for the creation of a leak-free composite PCM, which was then integrated with foam concrete made of CEM I 42.5R cement, water, quartz sand, and a foaming agent. Basalt-PCM was substituted into the mixture at 50% and 100% by weight of quartz aggregate. Comprehensive evaluations were conducted on the novel foam concretes with regard to their morphological, mechanical, physical, thermal, and TES properties. The results indicate that the incorporation of basalt-PCM causes a minor reduction in the dry unit weight of the mixtures and a reduction in compressive and flexural strength. However, the leak-proof basalt powder/capric acid composite displayed a phase transition behavior, melting at 28.5 °C with a latent heat of fusion (47.9 J/g), which retained 99.5% capacity after 500 melting-solidification cycles. The specimen with 100 wt% basalt-PCM exhibited a melting temperature and latent heat of 27.8 °C and 17.4 J/g, respectively. Additionally, the basalt powder/capric composite exhibited high thermal stability up to 156 °C, far above its normal operating temperature. The foam concretes incorporating the basalt-PCM demonstrated solar thermoregulation properties, maintaining a more stable and comfortable indoor temperature. These results suggest that the form-stable PCM-incorporating foam concretes developed in this study can be considered as environmentally friendly building materials for thermoregulation and energy conservation.

Evaluation of Thermal and Rheological Properties of Phase Change Material-Incorporated Asphalt Mastic with Porous Fillers

Incorporating phase change material (PCM) into paving materials can regulate the pavement temperature, improve the pavement durability, and mitigate the heat-island effects. In this research, porous fillers were used as the PCM carrier, and the thermal and rheological behaviors of the asphalt mastic with the PCM were evaluated. Two different carrier materials (diatomite and expanded perlite) and four types of PCMs were used in the study. The candidate filler, PCM, and proper blending ratios were determined based on the results of scanning electron microscope image analysis, the filter paper test, and the temperature sweep test. The thermal and rheological behaviors of the mastics with PCMs were further evaluated with different filler replacement ratios. Thermal analysis through a differential scanning calorimetry test, thermal conductivity and volumetric heat capacity test, and real-time temperature performance test were performed on the asphalt mastics. Rheological tests, including the complex shear modulus test, the bending beam rheometer test, and the linear amplitude sweep test, were also conducted. The modified mastics were found to have high heat capacity with the latent heat storage ability. The rheological analyses showed that with the addition of polyethylene glycol, while the low-temperature performance of the asphalt mastics was improved, the performance at intermediate and high temperatures was not adversely affected by the PCM.

Thermal heat transfer and energy modeling through incorporation of phase change materials (PCMs) into polyurethane foam

Decreasing HVAC energy consumption through insulation effectiveness enables low energy use, low carbon emissions, and high thermal comfort in sustainable buildings. PCMs for energy storage are an innovative option, but in buildings, their high thermal conductivity is a concern.The PCM latent heat of fusion and thereby it’s transition temperature has been a key parameter in PCM selection but little is known of the effect of PCM on building energy contributions arising from increasing thermal conductivity (k), density (ρ), and specific heat capacity (Cp). To resolve this, in this paper, two PCMs with transition temperature above and below the outdoor temperature incorporated in highly porous flexible polyurethane foam were evaluated using a one-dimensional (1D) foam core panel built in COMSOL Multiphysics®. The simulations were run using the summer season in a humid subtropical climate zone with an outdoor temperature of 35 °C. It was found that apart from the latent heat of fusion, the combined effects of high ρ and Cp could mitigate the increased k of PU-PCM composites to improve the insulation performance. Building energy modeling using EnergyPlus with the foam core incorporated into a structural insulated panel (SIP), revealed that the use of PCMs regardless of the transition temperature could reduce annual electricity consumption by 15–20%, with a significant amount of energy savings arising from the cooling load in summer.

Spectral transmittance changes in a PCM glass block affected by an artificial radiation source

Adaptive principles based on latent thermal energy storage together with its optimal modulation of optical properties in transparent façade systems represent one of the challenging solutions for reducing the energy consumption of buildings. Properly incorporated phase change material (PCM) may be a potential technique for passive solar system applications. This study focuses on the analysis of PCM’s optical changes on innovative building envelope components. A stable radiation source that most closely approximates the conditions of sunlight is essential for the characterization of new solar thermal systems. Hence the intensity and spectral distribution of the light source are the most important factors corresponding to natural sunlight. This contribution stems from previous experimental research focused on the investigation of the changes in the transparency of the PCM material, which is the result of the phase transformation from solid to liquid and vice versa under radiation exposure. The main challenge is to characterize the spectral optical properties in the PCM glass system. Accordingly, optical changes were analyzed experimentally using the spectrometry method. The measurements are based on a comparison of clear and PCM-filled glass blocks, affected by artificial radiation in a laboratory. The results revealed that PCM glass block may act as near-infrared absorbing and at the same time a highly transparent system in the visible region compared to the conventional air-based systems.

Study on foam concrete incorporated with expanded vermiculite/capric acid PCM – A novel thermal storage high-performance building material

A major part of energy consumption is reported from the residential and commercial buildings due to the large usage of mechanical devices to maintain a comfortable indoor ambiance. Thermal conductivity of the materials used in these buildings can be reduced by using low density materials and an efficient thermal energystorage strategy. In the present paper, the thermal performance ofa building envelope was improved by incorporating phase change material (PCM) into thefoam concrete mix. At first, PCM was developed by using a light weight material, expanded vermiculite (EV) impregnated with capric acid (CA) and ethyl alcohol (EA) under vacuum conditions. Different foam composite mixes were prepared and experimentally tested. Foam concrete mixtures with EV, CA-EA/EV based PCM, and PCM with added nano silica and coir fiber combinations (PSC) were prepared by the replacement of fine aggregate (M−sand) in various weight percentages. This study reveals that PCM with a CA to EV proportion of 55% (wt.) had the maximum adsorption and stability, as assessed through liquid leakage. In addition to improving thermal efficiency, PCM enhanced foam concrete composites showed improved mechanical, hydration, durability, and thermal characteristics. In comparison to the control foam concrete and PCM foam concrete mixes, the addition of nano silica and coir fiber added foam concrete mixtures (PSC) demonstrated improved strength and shrinkage qualities. These improved properties are attributed to the pozzolanic activity of nano silica and the bridging effects resulting from the fiber to micro cracks. Apart from the durability and strength characteristics, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA) were adopted to characterize the morphological, chemical, and thermal aspects of the different foamed concrete mixtures. The DSC results proved that the PSC-5% foam concrete mixture had latent heat capacities of 43.90 J/g for cooling and 69.16 J/g for heating, with melting and solidification temperatures of 31.51 °C and of 21.77 °C, respectively. TGA also revealed that theproposed PCM composite has a high thermal resistance. The PSC-5% shows bettercompatibilityas perSEM and EDS tests by the proper penetration of the nano silica in the foamed compositesthrough the pores. Finally, the thermal analysis tests demonstrated that the PSC-5% has a thermal conductivity of 0.129 W/m-K, which is 49.60% lesser than the foam concrete control sample, and also possesses an improved heat storage capacity, which ensures better thermal comfort in buildings.

Performance Enhancement of Photovoltaic-Thermal Modules Using a New Environmentally Friendly Paraffin Wax and Red Wine-rGO/H2O Nanofluid

Photovoltaic/thermal systems are one of the most efficient types of solar collectors because they absorb solar radiation and generate electricity and heat simultaneously. For the first time, this paper presents an investigation into the impact of red wine-rGO/H2O nanofluid and paraffin wax on the thermohydraulic properties of a photovoltaic/thermal system. The study focuses on three innovative nonlinear arrangements of the serpentine tubes. The effects of these materials and configurations are analyzed through numerical simulations. To improve the performance, environmentally friendly materials, including red wine-rGO/H2O nanofluid and paraffin wax, have been used. Various performative parameters such as electrical and thermal efficiency of the photovoltaic/thermal system, exergy, and nanofluid concentration were investigated. The results demonstrated a significant enhancement in the system’s performance when using innovative serpentine tubes instead of simple tubes for the fluid flow path. The use of paraffin C18 increases electrical efficiency, while the use of paraffin C22 improves thermal efficiency. Moreover, the incorporation of phase change materials along with the utilization of innovative geometries in the serpentine tube led to a notable improvement in the outlet temperature of the fluid, increasing it by 2.43 K. Simultaneously, it substantially reduced the temperature of the photovoltaic cells, lowering it by 21.55 K. In addition, the new model demonstrated significant improvements in both thermal and electrical efficiency compared to the simple model. Specifically, the maximum thermal efficiency improvement reached 69.2%, while the maximum electrical efficiency improvement reached 11.7%.

Effect of two organic phase change materials on the thermal performance of asphalt pavements

ABSTRACT Higher temperature is one of the key reasons for thermal distresses in asphalt pavement. It also adds to the Urban Heat Island (UHI) effect as it influences the near-surface air temperature. To design cooler pavements, phase change materials (PCMs) can be incorporated into asphalt pavements. However, considering the negative effects of PCM leakage on the physical and rheological properties of asphalt binder, a cent-percent effective core-shell encapsulated PCM suitable for asphalt pavement applications was developed under this study. With the incorporation of two organic mixture (OM) based PCMs, i.e., OM-35 and OM-42, a peak decrease in the pavement surface temperature of 3.05 °C and 4.36 °C, respectively were observed under the field condition. Furthermore, from the long-term thermal performance assessment, it was found that the magnitude of temperature reduction depends on the phase change temperature and latent heat of PCM. The season of occurrence of the peak temperature reduction depends on the phase change temperature of the PCM. Due to PCM solidification, the increase in night-time pavement surface temperature was observed to be about half of that during day time. Further, the statistical analysis reveals that the decrease in pavement surface temperature due to PCM incorporation is significant and consistent.

Thermal management of shelter building walls by PCM macro-encapsulation in commercial hollow bricks

Maintaining building indoor temperature within comfort zone has been identified as one of the major reasons for energy consumption. The incorporation of phase change materials (PCMs) in various regions in buildings is introduced as a solution that can significantly reduce energy consumption. In the current research, a three-dimensional computational fluid dynamics approach is taken to evaluate the influence of incorporating three PCMs from the Rubitherm® RT line (RT15, RT18, and RT22) in two widespread commercial hollow brick types in Iran for keeping the indoor environment of a shelter warm in a cold climate. These enhanced bricks are compared with their solid and hollow counterparts. Furthermore, efforts were made to examine various configurations of these PCMs, with melting temperatures in obedience or contrast with the thermal stratification of the bricks. Several combinations of the PCM with air layers are studied to assess the best way to place the air and PCM layers. It was found that the RT18 PCM-filled brick can present lower heat fluxes than the hollow one for over 42 h. Also, the findings showed that RT22 PCM-filled brick can provide 66.79% lower average heat flux compared to the hollow brick for the first 24 h of the process.

Study on Phase Change Material in Grooved Bricks for Energy Efficiency of the Buildings

Phase change materials (PCMs) are an interesting technology due to their high density and isothermal behavior during phase change. Phase change material plays a major role in the energy saving of the buildings, which is greatly aided by the incorporation of phase change material into building products such as bricks, cement, gypsum board, etc. In this study, an experiment has been conducted with three identical small chambers made up of normal, grooved and PCM-treated grooved bricks. Before the inclusion of PCM in grooved bricks, PCM material behavior has been studied by different techniques such as DSC, TG/DTA, SEM, and XRD. Thermal properties and thermal stability were investigated by differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA) respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the microstructure and crystalloid phase of the PCM before and after the accelerated thermal cycling test (0, 60, 120). These three identical model rooms built were exposed at a temperature just above 40 °C with a heater. When the maximum outdoor temperature was 40-41 °C, then the temperature of the PCM-treated grooved chamber was 32-33 °C. The PCM-treated wall was tested and compared with a conventional and grooved wall. The difference between the PCM-treated grooved chamber and the untreated one was 8-9 °C. PCM-treated bricks provided more efficient internal heat retention in summer when the outside temperature increased.

Study on shape-stabilised paraffin-ceramsite composites with stable strength as phase change material (PCM) for energy storage

The massive energy consumption in construction has been a critical challenge for sustainable development. Incorporating phase change material (PCM) into construction materials is an effective way to improve energy management. In this work, the paraffin with a melting point of ∼ 28 °C and latent heat of ∼ 193 J/g was absorbed into fly ash ceramsites (artificial porous aggregate) under vacuum pressure. The ceramsite had sizes ranging from 7 to 13 mm, within the size range of coarse aggregates in concrete. The main properties of the raw ceramsite, paraffin, and paraffin/ceramsite composite were tested using Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), microscope, leakage testing, mechanical testing, etc. The PCM incorporation ratio was 45.33 wt%. This incorporation value is adequate for PCM composite in concrete to show the significant performance of thermal regulation. The leakage test result shows excellent stability of the PCM carrying in the ceramsites. The PCM-ceramsite composites present intact structures under heating and cooling cycles because of the low-volume expansion of paraffin. Solidified PCM inside the ceramsite particles improve the strength of the composites. Microcharacterization indicates that the connected pores/cracks inside the ceramsite particles are the primary path, while unconnected pores have little benefit for PCM incorporation. Small pores have better PCM retaining efficiency, especially if they are located at the sub-deep layer. Large pores provide ample space for PCM but have adverse effects on to the strength of the PCM-ceramsite composites. Finally, an optimal structure of ceramsites was proposed for PCM.

Form stable phase change material supported by sensible and thermal controllable thermistor

A negative temperature coefficient (NTC) thermistor with thermal sensing and control capabilities was manufactured by adopting form stable phase change materials (PCMs). The incorporation of PCMs expanded their potential uses by providing a stable and continuous circuit. The PCMs underwent a nearly isothermal phase transition process, which lasted for a long time without significant temperature fluctuations. To hold the pure PCM and prevent leakage during melting and cooling processes, a graphene aerogel was employed as a supporting material. Compared with microsphere PCM composite, the graphene aerogel had a high porosity. The PCM composite retained over 98 wt% of the working material for thermal energy. The NTC thermistor probe was inserted into the PCM composite to construct a thermal sensible device. The PCM surrounded NTC thermistor exhibited an excellent thermal stability and could maintain the output current in the circuit. These findings suggest that the form stable PCM composite can be utilized in thermal controllable systems to prevent overcurrent and safeguard electronic devices.

Prediction of the mechanical behavior of mortars incorporating phase change materials using data mining techniques

Nowadays, it is imperative to reduce the energy bill in order to contribute to a more sustainable planet. In this sense, the use of materials that contribute to the energy efficiency of buildings is a very important contribution to achieve this goal. Mortars incorporating phase change materials (PCM) can make an important contribution to this end, due to its thermal storage capacity, increasing the energy efficiency of buildings. In this work several mortars with different PCM contents were developed, using different binders (cement, aerial lime, hydraulic lime and gypsum). The aim of this study was to apply data mining techniques such as artificial neural networks (ANN), support vector machines (SVM) and multiple linear regressions (MLR) to forecast the compressive and flexural strengths of these mortars at different exposure temperatures. It was concluded that ANN models have the best predictive capacity both for compressive strength and flexural strength. However, the SVM models have a flexural strength forecasting capacity very close to ANN models.

Parametric Optimization of a Truncated Conical Metal Hydride Bed Surrounded by a Ring of PCM for Heat Recovery.

Metal hydride (MH) hydrogen storage needs an external heat source to release the stored hydrogen. To enhance the thermal performance of MHs, the incorporation of phase change materials (PCM) is a way to preserve reaction heat. This work proposes a new MH-PCM compact disk configuration (i.e., a truncated conical MH bed surrounded by a PCM ring). An optimization method is developed to find the optimal geometrical parameters of the MH truncated cone, which is then compared to a basic configuration (i.e., a cylindrical MH surrounded by a PCM ring). Moreover, a mathematical model is developed and used to optimize the heat transfer in a stack of MH-PCM disks. The optimum geometric parameters found (bottom radius of 0.2, top radius of 0.75 and tilt angle of 58.24) allow the truncated conical MH bed to reach a faster heat transfer rate and a large surface area of higher heat exchange. Compared to a cylindrical configuration, the optimized truncated cone shape enhances the heat transfer rate and the reaction rate in the MH bed by 37.68%.

Machine learning model for transient exergy performance of a phase change material integrated-concentrated solar thermoelectric generator

Despite the merits of incorporating phase change materials in concentrating solar thermoelectric generating systems, the following research gaps still need to be filled to make the technology viable. Past research efforts focused on pulsed rectangular and sinusoidal heat flux forms which differ from actual transient weather data obtainable under field exposure. Additionally, a comprehensive exergy performance modeling of the system is yet to be presented in the literature, hence, there is no known thermodynamic implication of incorporating phase change materials in thermoelectric systems from a first and second law perspective. Finally, optimization insights obtained for designing these systems are based on inefficient, computationally expensive, and time-consuming numerical solvers or experimental methods which significantly hinder the ease at which useful design insights are obtained. This work aims to fill in these gaps by presenting the first-ever exergy performance investigation of a paraffin wax integrated thermoelectric generating system using data-driven surrogate machine learning models trained with numerically generated data computed from actual 12 h transient timeseries weather data collected every minute and averaged for a 10-year period (2010–2020). Results show that for an optical concentration of 10, the incorporated system with phase change material provides a 25%, 57%, 25%, and 56% improvement in the thermoelectric temperature difference, power generation, exergy efficiency, and thermodynamic irreversibility of the stand-alone system, respectively, without phase change material. Furthermore, the incorporated system generates electricity for 2 more hours into the night when solar irradiance is unavailable. Finally, the cheap surrogate machine learning model accurately predicts the thermodynamic performance of the stand-alone and incorporated systems with an almost zero error and almost unity coefficient of determination in just 5 s after the numerical method has taken 24 h to generate the data, indicating a 17,280-computation time saving.

Inclusion of microencapsulated phase change materials in waterborne paints to enhance radiative cooling performance

Radiative cooling materials are a promising technology for reducing energy demand for thermal control in buildings and surfaces. Paint formats are versatile and relatively inexpensive implementations of this technology. Waterborne polyurethane paints are environmentally friendly coating systems that possess high abrasion resistance and durability. However, the implementation of radiative cooling in polyurethane paints is limited due to their less favorable optical properties. In this work, the addition of phase change materials (PCM) to the paint formulation to enhance cooling performance is investigated. Capric acid, encapsulated in silicon dioxide particles via a sol–gel process, was selected as the PCM, and barium sulfate particles were used as paint pigments. At a fixed total particle volume concentration, the incorporation of PCM increases the effective heat capacities of paints. However, the solar reflectance decreases as the PCM volume concentration increases, especially above 0.25. An outdoor test reveals that the inclusion of the PCM reduces the heat load in the paint and consequently enables sub-ambient cooling. This study suggests that the PCM components can enhance the cooling performance of radiative cooling paint systems that struggle to achieve sub-ambient cooling.