Incorporation Of Phase Change Materials Research Articles

Electrically Reconfigurable Phase-Change Transmissive Metasurface.

Programmable and reconfigurable optics hold significant potential for transforming a broad spectrum of applications, spanning space explorations to biomedical imaging, gas sensing, and optical cloaking. The ability to adjust the optical properties of components like filters, lenses, and beam steering devices could result in dramatic reductions in size, weight, and power consumption in future optoelectronic devices. Among the potential candidates for reconfigurable optics, chalcogenide-based phase change materials (PCMs) offer great promise due to their non-volatile and analogue switching characteristics. Although PCM have found widespread use in electronic data storage, these memory devices are deeply sub-micron-sized. To incorporate phase change materials into free-space optical components, it is essential to scale them up to beyond several hundreds of microns while maintaining reliable switching characteristics. This study demonstrated a non-mechanical, non-volatile transmissive filter based on low-loss PCMs with a 200 µm×200 µm switching area. The device/metafilter can be consistently switched between low- and high-transmission states using electrical pulses with a switching contrast ratio of 5.5 dB. The device wasreversibly switched for 1250 cycles before accelerated degradation took place. The work represents an important step toward realizing free-space reconfigurable optics based onPCMs. This article is protected by copyright. All rights reserved.

Numerical and experimental analysis of battery thermal management of 21700 Nickel Manganese Cobalt lithium-ion battery

High discharge rates in 21700 NMC Lithium-Ion Batteries (LIBs) leads to elevated temperatures, negatively impacting battery performance and longevity. This study examines the integration of phase change materials to address this issue. Phase change materials absorb heat through sensible and latent heat mechanisms, effectively reducing battery temperature. At discharge rates of 0.5 C, 1 C, and 1.5 C, phase change materials decreased battery temperature by 4.12 %, 7.32 %, and 8.16 %, respectively, ensuring optimal operating conditions. Incorporating phase change materials within battery modules minimizes cell spacing, leading to a smaller battery pack size and reduced costs. This compact design is achieved by exploiting phase change materials ability to store and release large amounts of heat while maintaining a nearly constant temperature. Furthermore, analyzing temperature variations across diverse surfaces within battery modules provides valuable insights for cooling technology development. The integration of Phase Change Materials effectively regulates temperatures, particularly under high discharge rates, offering significant implications for battery performance and longevity. This study highlights the potential of phase change materials in improving LIBs thermal management, which is crucial for electric vehicle applications and other high-power-demand scenarios. By addressing temperature-related challenges, phase change materials integration contribute to the advancement of more efficient, reliable, and safer LIBs.

Physical and Mechanical Properties of Fiberboard Made of MDF Residues and Phase Change Materials

The wood-based panel industry is experiencing an excessive accumulation of solid residues from the production of medium-density fiberboard (MDF) panels and moldings. It is possible to create new MDF products with acceptable physical and mechanical properties by revaluing MDF residues. Additionally, those products’ thermal properties can be improved by incorporating phase change materials (PCMs). This study aims to develop a wood-based fiberboard made of MDF residues, capable of storing thermal energy. Two types of PCMs (liquid and microencapsulated), two PCM ratios (2% and 6%), and two types of adhesives (urea-formaldehyde and phenol-formaldehyde) were used to produce eight different types of panels. The vertical density profile, thickness swelling, water absorption, internal bond (IB), and static bending properties—modulus of elasticity (MOE) and modulus of rupture (MOR)—were determined for each panel type. The specific heat of the panels was also determined. The results show the panels’ densities were greater than 700 kg/m3. Thickness swelling in water improved by 23% compared to the reference value of the control panel PCMs after PCM incorporation. The highest IB value was 1.30 MPa, which is almost three times the minimum required by regulation standards. The incorporation of PCMs reduced the panels’ bending properties compared to the properties of the control panels. Even though the values obtained are sufficient to comply with the minimum values set out in ANSI standard A208.2 with an MOE value of 2072.4 MPa and the values obtained are sufficient to comply with the minimum standards with an MOE value of 2072.4 MPa and an MOR value of 16.4 MPa, when microencapsulated PCM is used, the specific heat of the panels is increased by more than 100% over that of the control panels. This study developed fiberboards with adequate physical and mechanical properties and capable of storing thermal energy.

Research Progress of Photovoltaic Cooling Systems Based on Phase Change Materials: An Overview

Photovoltaic technology plays a crucial role in harnessing renewable energy. While photovoltaic panels directly convert solar energy into electricity, more than 50% of solar radiation is lost as waste heat, diminishing the overall efficiency of the panels. This study reviews various cooling technologies for photovoltaic systems, focusing on the use of phase change materials for cooling in photovoltaic systems. Phase change materials, known for their high latent heat capacity, are extensively used in thermal energy storage applications. Incorporating phase change materials in photovoltaic systems can increase thermal storage potential by 30–50% compared to conventional systems, leading to a 70% extension in heat storage duration and various levels of enhanced power output. The main purpose of the article is to review the advantages and disadvantages of various technologies, determine the research direction of phase change materials for cooling systems in photovoltaics, and ensure the reliability of this technology.

Selective gas detection using phase change material infused photonic crystal

A photonic crystal-based optical gas detector is proposed, incorporating phase change material (PCM) to modulate the sensing properties. The multi-gas detection process is designed in the range of 650 nm to 2500 nm. Ge2Sb2Te5 (GST) is employed as a phase change material with significant optical property variations. It can exist in two self-sustaining, bi-stable phases: a crystalline GST (CGST) and an amorphous GST (AGST). The dielectrics (i.e., Si, SiO2, GST, and Au) are used in various combinations, such as Au-Si, Au-Si-SiO2, Au-GST-SiO2, and GST-Au. Plane light waves are used to model the nanoporous structures over a broad wavelength range (650 nm to 2500 nm). The optical spectral response of the structures, including the reflectivity spectrum, power absorption spectrum, and electric field distribution, is investigated by varying the GST thickness, dimension, and geometry of the nanoholes. Liquid ammonia has the highest selectivity of any gas from 650 nm to 1000 nm, at about 29%, whereas carbon monoxide has the maximum sensitivity of 32%. The interchanging of layers increases the sensitivity of all the gases. With a sensitivity and selectivity of 78% and 40%, respectively, carbon monoxide exhibits the greatest values.

Numerical Study of the Thermal Behavior of a Wall Containing Phase Change Material (PCM) in a Hot and Dry Climate

Current buildings in Burkina Faso, particularly in the Sahelian zone, built with local materials are energy-intensive and sources of discomfort for the occupants. However, the role of housing is to provide man with shelter which protects him from external climatic conditions and offers him thermal comfort.  In this work, we present a numerical study of the thermal behavior of a wall containing a phase change material (PCM) in the Sahelian zone. The MCP used in this study is RT27 paraffin with a melting temperature of 27°C and a latent heat of fusion of 179kJ/kg. The equations obtained were adimensionalized and discredited by the finite element method and solved using COMSOL Multiphysics software version 5.3. To this end, we were interested on the one hand in the study of the evolution of the flow of heat and the temperature at the level of the external and internal walls of the wall. On the other hand, we studied the effect of the location of a layer of PCM mortar, simple plaster or cement plaster on the temperature of the internal wall of the wall. The results show the magnitude of heat flux and temperature is greatly reduced by the incorporation of PCM into the wall.

A Review of Heat Dissipation and Absorption Technologies for Enhancing Performance in Photovoltaic–Thermal Systems

With the growing demand for photovoltaic (PV) systems as a source of energy generation that produces no greenhouse gas emissions, effective strategies are needed to address the inherent inefficiencies of PV systems. These systems typically absorb only approximately 15% of solar energy and experience performance degradation due to temperature increases during operation. To address these issues, PV–thermal (PVT) technology, which combines PV with a thermal absorber to dissipate excess heat and convert it into additional thermal energy, is being rapidly developed. This review presents an overview of various PVT technologies designed to prevent overheating in operational systems and to enhance heat transfer from the solar cells to the absorber. The methods explored include innovative absorber designs that focus on increasing the heat transfer contact surface, using mini/microchannels for improved heat transfer contiguity, and substituting traditional metal materials with polymers to reduce construction costs while utilizing polymer flexibility. The review also discusses incorporating phase change materials for latent heat absorption and using nanofluids as coolant mediums, which offer higher thermal conductivity than pure water. This review highlights significant observations and challenges associated with absorber design, mini/microchannels, polymer materials, phase change materials, and nanofluids in terms of PV waste heat dissipation. It includes a summary of relevant numerical and experimental studies to facilitate comparisons of each development approach.

Hybrid cooling system with phase change material and liquid microchannels to prevent thermal runaway propagation within lithium-ion battery packs

Thermal runaway propagation in battery pack can cause catastrophic hazards without timely countermeasures. This paper presents the establishment of lumped thermal resistance model for battery pack and introduces an innovative hybrid thermal management system designed to suppress thermal runaway propagation. First, a heat generation model describing the reaction dynamics of cell thermal runaway is developed and validated by experiment. Subsequently, a lumped thermal resistance network is formulated for the large-scale battery pack using electrical circuit elements and simulation studies for the thermal runaway propagation are carried out. The results reveal that the thermal runaway propagation progress triggered by four cells can accelerate by nearly 40 % compared to that initiated by a single cell. Consequently, a hybrid thermal management incorporating phase change material and liquid microchannels is designed. Comparative analysis with individual cooling systems demonstrates the superior effectiveness of the proposed system in suppressing the first round of thermal runaway propagation. The temperatures of neighbor cells only have a marginal climb to about 80 ℃ in the initial 600 s, which is well below the thermal runaway triggering temperature. This work can provide valuable insights into the structural design of thermal management systems for battery packs in practical applications.

Integration of Phase Change Materials in Service Areas of Building Envelopes for Improved Thermal Performance: An Experimental Study in Saudi Arabia

This experimental study explores the integration of Phase Change Materials (PCMs) within building envelopes. The research specifically centers on the utilization of two microencapsulated paraffin-based PCMs with melting points of 37 °C and 43 °C. The study assesses their performance within cement and gypsum-based PCM composites, concentrating on service areas often overlooked in thermal analysis, including underground garages, staircases, and utility rooms. The experimental setup included constructing three chambers inside an underground garage during the hot months of June and July in Saudi Arabia. Two chambers were assigned to integrate the PCM, while the third chamber served as a control without PCM. The experiment unfolds in two phases. In the initial phase, the objective was to determine which PCM is more effective in reducing the heat load inside the chambers. This led to the adoption of the 43 °C PCM for the subsequent stage. The adoption of the 43 °C PCM resulted in a fourfold decrease in heat compared to the 37 °C PCM. The second phase investigates the integration of the selected PCM with cement and gypsum composites. The percentage of PCM incorporated into the concrete and gypsum composites was determined experimentally. For cement-based composites, the identified percentage that maintains material integrity is 20%, and for gypsum-based composites, it is 22%. The findings demonstrate a significant reduction in cooling load with PCM incorporation, with cement-based composites exhibiting superior thermal performance compared to gypsum-based alternatives and reducing the heat load by approximately 63%. Additionally, it was observed that concrete reduced the highest temperature during the day by 5.2 °C, which equates to about a 10% reduction, further enhancing comfort. Conducted over the course of two summer seasons, this study contributes valuable insights toward improving the quality of life for building occupants, considering various factors such as their living environment.

Enhancing solar distillation through beeswax-infused tubular solar still with a heat exchanger using parabolic trough collector

This scholarly investigation elucidates the imperative for advancing solar thermal desalination systems, an exigency compounded by the twin global challenges of burgeoning solar implementational proliferation alongside intensifying non-potable water scarcity. The primary research objective underlines manifesting the latent productivity within passive tubular solar still (TSS) configurations via an amalgamated active system through the integration of metallic thermal transfer constituents (heat exchanger) alongside parabolic trough collector (PTC). Additionally, accelerated vapor condensation kinetics are catalyzed by the inclusion of beeswax phase change material (PCM) within the tubular metallurgies. A thorough empirical analysis of said system scrutinizes the synergistic fusion of concentrated solar thermal capacities using concentrated solar power (CSP) paradigms in tubular solar photo-thermal frameworks with beeswax constituting the auxiliary PCM thermal sink. A bifurcated data set provides experimental controls lacking PCM alongside PCM incorporation with repeating data gathering phases assessing comparative solar distillation system performance. The culminating system productivity and efficiency results exhibit a 66.18 % and 54.04 % respectively enhancement. Thus, the amalgamation of PTC-augmented TSS with metallic thermal exchangers & PCM beeswax integration introduces pragmatic pathways for advancing intensive solar-powered desalination output. Further academic interrogation of enabling thermal and optical phenomena driving said performance optimization remains imperative.

Numerical simulation of various PCM container configurations for solar dryer application

In the context of solar dryers, where drying time is constrained by available sunshine hours and excessive heat during these periods can potentially lead to mineral loss in food, the incorporation of phase change material (PCM) for thermal energy storage emerges as a viable solution. However, the response time of PCMs plays a major role in its charging and discharging in solar dryer performance, prompting extensive research into PCM container configurations to reduce this limitation. Investigations have been conducted through numerical simulations and experimental studies to explore various configurations of PCM. In this study, four distinct container configurations were employed, alongside the introduction of fins, with two variations: solid and hollow. In this regard, Paraffin RT58, with its melting point closely aligned with the operating temperature of the solar dryer, is considered a suitable choice in simulation using ANSYS Fluent. The simulation results revealed that the horizontal rectangles demonstrate the quickest rates for melting and solidification, whereas the cylindrical shape exhibits the most extended durations for these processes. The introduction of fins has a notable impact on reducing both melting and solidification times, with a further decrease observed as the number of fins increases. While solid fins provide slightly superior reductions in melting and solidification times, opting for hollow fins presents benefits in terms of material efficiency, weight reduction, and cost savings.

The Thermal Properties of an Active–Passive Heat Storage Wall System Incorporating Phase Change Materials in a Chinese Solar Greenhouse

The use of renewable energy for food and vegetable production is a potential sustainable method to reduce fossil energy consumption. Chinese solar greenhouses (CSGs) are horticultural facility buildings in the northern hemisphere that use solar energy to produce off-season vegetables in winter. The north wall heat storage and release capacity of CSG has a significant impact on the indoor thermal–humidity environment. However, common traditional solar greenhouses commonly have problems such as insufficient heat storage and release, thick temperature stability zones inside the walls, and inability to dynamically regulate the entire greenhouse environment. Therefore, a novel active–passive heat storage wall system (APHSWS) incorporating phase change materials has been developed to promote the thermal performance of the CSG and its internal temperature of the thermal storage wall in this paper. Through experimental and simulation methods, the heat storage and release of the APHSWS and its impact on the greenhouse environment are investigated. The findings indicate that the APHSWS has increased the wall heat storage and release capacity, compared to the ordinary greenhouse without the APHSWS, in three typical weather conditions in winter (i.e., sunny, overcast, and cloudy); the average temperature of greenhouse with the APHSWS has increased in indoor air temperature, wall surface temperature, and soil surface temperatures of 1.58–6.06 °C, 2.71–6.58 °C, 0.91–6.39 °C, respectively; and during the experiment, the greenhouse with the APHSWS has a monthly average daily effective accumulated temperature of 1.39 times, 1.18 times, 0.60 times, and 0.20 times that of the ordinary greenhouse without the APHSWS from December to March of the next year, respectively. Under typical sunny conditions, the greenhouse wall heat storage capacity increased by 1.59–2.44 MJ/m2 and the heat release capacity increased by 0.97–1.17 MJ/m2. At the direction of wall thickness, the temperature at each point inside the wall with the APHSWS is always higher than that of ordinary wall without the APHSWS. In addition, the operating cost of the APHSWS in winter is analyzed.

Coaxial Fibres Incorporated with Phase Change Materials for Thermoregulation Applications

Nowadays, the growing concern about improving thermal comfort in different structures (textiles, buildings, and pavements, among others) has stimulated research into phase change materials (PCMs). The direct incorporation of PCMs into composite materials can cause mechanical impacts. Therefore, this study focuses on the design of phase change coaxial fibres (PCFs), using commercial cellulose acetate (CA) or recycled CA obtained from cotton fabrics (CAt) as the sheath and polyethylene glycol (PEG) 2000 as the core, via the wet spinning method; the fibres vary in molecular weight, concentration and ejection velocity. The fibres were assessed for their optical, chemical, thermal, and mechanical properties. The presence of PEG2000 is confirmed in the core of the fibres. Thermal analyses revealed a mass loss at high temperatures, attributable to the presence of PEG2000. Notably, the fibres with CA (Mn 30,000) showed superior thermal and mechanical performance. The melting point of PEG2000 incorporated into these PCFs coincided with the melting point of pure PEG2000 (about 55 °C), with a slight deviation, indicating that PCFs were obtained. Finally, the results point to the application of the fibres in civil engineering materials requiring a phase change between 50 and 60 °C, providing promising prospects for their use in applications requiring thermoregulatory properties.

Thermal behavior of flexible and breathable sandwich fibrous polyethylene glycol (PEG) encapsulations

Textiles incorporating phase change material have attracted increasing attention due to their temperature regulating function. Although a great progress has been made in the development of phase change material textiles, it has been found that the loading amount of phase change materials is limited by other final properties. Recently, we have proposed a sandwich fibrous phase change material encapsulation with a relatively high phase change material loading amount, which is a multi-layer fabric structure containing phase change material. However, the breathability of sandwich fibrous phase change material encapsulation should be improved because there is no path for air to penetrate through. In this work, the sandwich fibrous phase change material encapsulation structure with polyethylene glycol as phase change material is modified by introducing different air pockets in the thermal function layer ranging from 19% to 64%. The leakage phenomenon, phase transition behavior, thermal energy storage, breathability, T-history and practicality of the breathable sandwich fibrous phase change material encapsulations are investigated. As a result, the maximum polyethylene glycol loading amount of the phase change materials pocket is 83 wt%, and there is no leakage of polyethylene glycol during working time. The overall enthalpy value of the breathable sandwich fibrous phase change material encapsulation ranges from 27 J/g to 48 J/g. The optimal air permeability and water vapor resistance of the breathable sandwich fibrous phase change material encapsulation is 9 mm/s under 100 Pa and 34.5 m2 Pa W−1. Furthermore, the heterogeneous heat transfer through the breathable sandwich fibrous phase change material encapsulation is found due to the complicated thermal resistances of the hybrid thermal functional layer. In addition, for breathable sandwich fibrous phase change material encapsulation, the flexibility, hydrophobicity, self-cleaning property, abrasion resistance, and stability after water immersion are found. We believe the research has a great potential in various applications related to phase change material.

Energy performance analysis of alternative building retrofit interventions for the four climatic zones of Greece

Climatic conditions determine which retrofit strategy can result in a satisfactory improvement of a building's thermal performance. This study systematically investigates alternative retrofit actions, as standalone and in combination, and assesses their energy performance. The retrofit actions include i) insulation on the external walls, ii) the incorporation of phase change material (PCM) on the roof and the increase of the building thermal inertia, iii) a mechanical ventilation system with a summer period operation, and iv) a cool roof coating. The energy analysis concerns a typical two-story family building and the four climatic categories of Greece and is conducted with the INTEMA.building tool, a dynamic energy analysis software developed in Modelica language. The importance of the present study is that it serves as a guideline for the selection of the energetically optimum single retrofit or multiple-retrofit strategy regarding a building's location climatic data, and provides calculations concerning the annual heating and cooling loads, and the corresponding heat pump electricity consumption. The retrofit actions of external wall insulation and PCM roof addition are characterized as more effective in reducing a building's heating energy loads, while the mechanical ventilation system and cool roof coating are more effective in reducing a building's cooling loads. The quadruple retrofit strategy results in the maximum electricity savings for Heraklion (28.01%), Athens (21.15%), and Thessaloniki (16.54%), while the triple retrofit strategy which does not include the cool roof coating, results in the maximum electricity savings for Kastoria (10.79%). Lastly, an economic analysis of the energetically optimum renovation strategies is conducted.

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

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

Experimental investigation of hybrid vacuum tube solar water heater/parabolic concentrator integrated with phase change material and nanofluid as HTF simultaneously; energy and exergy assessments

ABSTRACT Solar water heaters suffer from fluctuating hot water production due to unpredictable weather changes throughout the day. In this study, the hybrid configuration of a vacuum tube solar water heater with a parabolic solar concentrator, in conjunction with the application of paraffin as a phase change material, is employed as a novel approach to address this problem. Furthermore, the study investigates the utilisation of a nanofluid (0.05%, 0.1%, and 0.2% mass) containing Al2O3 and ZnO nanoparticles dispersed in water-ethylene glycol (base fluid) as the medium fluid to enhance thermal performance. The experimental results revealed that the utilisation of 0.2% mass ZnO and Al2O3 nanofluids led to a considerable increase of 10.74% and 7.25%, respectively, in the maximum reservoir temperature. This resulted in a respective average thermal efficiency improvement of 41.6% and 33.9% compared to the base fluid. Furthermore, the maximum exergy efficiency of the system exhibited a significant increment of 54% and 40.1% compared to the base fluid. Moreover, the incorporation of phase change material in the system effectively minimised temperature fluctuations.

Core-shell PCM encapsulation model for thermoregulation of asphalt pavements

The implementation of cooler pavements plays an important role in alleviating the urban heat island (UHI) effect and extending the lifespan of pavements. One potential approach to develop cool pavements involves the incorporation of phase change materials (PCMs). In this study, a numerical investigation is conducted to evaluate the effectiveness of incorporating core–shell encapsulated PCMs within asphalt pavements. To facilitate this analysis, an enthalpy-porosity-based heat transfer model is developed, and its accuracy is validated through experimental data obtained in-house. For this study, commercially available PCMs, namely Organic Mixture 35 (OM 35) and Organic Mixture 42 (OM 42), encapsulated within hollow steel balls are used. The outcomes of the investigation reveal that the inclusion of core–shell encapsulated PCMs is a viable method for reducing the temperature of asphalt pavements. Further, it is found that as the thermal conductivity of asphalt pavements increases from 1.21 to 2.41 W/mK, there is corresponding proportional increase in the temperature reduction achieved by integrating the PCMs with the pavements. The proportional temperature reduction with increase in thermal conductivity of asphalt pavements are found to be 3.55 °C using OM 35 and 3.37 °C using OM 42 respectively. It is worth noting that while the thermal characteristics of the steel balls exhibit a limited influence on temperature reduction, their physical attributes should be given careful consideration during the design phase of asphalt pavements.

Molecular dynamics study of paraffin/polyethylene blends as phase change materials for energy efficiency in buildings

ABSTRACT The greenhouse gas emissions and global energy consumption associated with construction materials can be greatly reduced by incorporating phase change materials into buildings. These materials can absorb and release energy during a phase transition, thus reducing the energy consumption while achieving human thermal comfort. Molecular dynamics simulations were used to study the miscibility of both linear and branched polyethylene with two types of paraffin (octadecane and hexatriacontane) at two different temperatures. The results showed that blending was better at high temperatures for both polymers, and branched polyethylene was more miscible with both paraffins than linear polyethylene was. Hexatriacontane exhibited better blending characteristics. From the molecular dynamics results, we concluded that linear polyethylene/paraffin blends were more suitable as phase change materials in buildings than branched polyethylene/paraffin blends, as they were miscible at high temperatures but separated into two phases at ambient temperature. The optimal blends were subsequently incorporated into a cement model to study their influence on the mechanical properties of this construction material. The introduction of the blends into the cement model deteriorated its mechanical properties.

Enhanced performance and stability of a solar pond using an external heat exchanger filled with nano-phase change material

Salinity gradient solar ponds are a promising technology for harnessing/storing solar thermal energy. The energy storage capacity of solar ponds can be enhanced by incorporating phase change materials (PCMs). However, the low thermal conductivity of PCMs can negatively affect energy charging/discharging rates. In this study, an external energy storage system filled with CuO nanoparticle-enhanced PCM was employed to improve the performance and stability of a solar pond. The results were compared with water and pure PCM (paraffin) as control materials. Energy and exergy analysis was used to assess the effects of nanoparticles and their concentration on the overall solar pond performance. According to the results, the upper convective zone temperature remained consistent across all experiments and varied within the same range throughout the day. A slight temperature variation at specific times indicated the stability of the developed solar pond system. The system's exergy (energy) efficiency was increased from 10.72% (51.83%) for water to 14.71% (70.1%), 22.77% (82.13%), and 25.93% (87.58%) for PCM, PCM with 1 wt% nanoparticles, and PCM with 2 wt% nanoparticles, respectively. Incorporating nanoparticle-enhanced PCMs in external heat exchangers can effectively improve the stability and performance of solar pond systems.