Influence Of Phase Change Materials Research Articles

Influence of PCMs on thermal performance of wet fire protective clothing

The inclusion of phase change materials (PCMs) in firefighting protective clothing (FPC) has been previously shown to be beneficial during the exposure stage, but detrimental in the post-exposure, mainly due to PCM latent heat release towards the skin, after the exposure. It is unclear whether that is also the case for when the FPC is wet. Hence, in this study, a one-dimensional numerical approach is used to study the effect of PCM parameters (PCM mass, melting temperature) and global heat flux, on the thermal performance of a wet fire protective clothing. It is concluded that under wet conditions, the PCM amount, and its phase change temperature have a significant effect on thermal performance, depending on the heat exposure scenario considered. Great benefits are observed in introducing PCMs to prevent water condensation near the skin, but at the cost of greater PCM re-solidification skin damage.

Influence of phase change material and nano silica aerogel aggregates on the characteristics of cementitious composite: An experimental and predictive study

This paper studies the influence of two high-performance thermal insulating materials including aerogel and phase change materials (PCM) aggregates, on the key characteristics of cementitious composites in experimental and predictive aspects. Thermal conductivity (ThC), rapid chloride migration test (RCMT), permeable pore volume, compressive strength, dry density, and microstructural analysis were performed for the mechanical properties. Moreover, Least Squares Support Vector Regression (LSSVR) as a machine learning method was introduced to evaluate and provide a proper method for non-destructive evaluation of parameters. The results of experiments indicated that both aerogel and PCM aggregates were highly effective although the aerogel showed more efficiency in enhancing the thermal insulation property of cementitious mixtures. In addition, the compressive strength of the mixtures with PCM composites was higher than the aerogel aggregates, where the compressive strength of the mixture containing 20 % paraffin was 50 % higher than the aerogel mixture with similar incorporation levels. Moreover, the mixtures with PCM aggregates had significantly lower water and chloride permeability compared to those of plain mixtures, and mixtures consisted of aerogel aggregates. The scanning electron microscope (SEM) analyses, also, revealed that the use of the aerogel aggregates led to an open and porous structure of the mixtures; however, PCM aggregates had a weak interfacial transition zone (ITZ) in the vicinity of cement paste. Furthermore, LSSVR model provided a close prediction of the effective parameters with an acceptable accuracy in capturing the influences of important parameters.

Enhancing thermal performance and optimization strategies of PCM-integrated slab-finned two-fluid heat exchangers for sustainable thermal management

This research investigates the influence of phase change material (PCM) distribution, fin density, and PCM type on the thermal performance of a slab-finned cross-flow PCM heat exchanger (HEX). The aim is to develop a highly efficient PCM-HEX system for enhanced thermal intermittency management. Computational fluid dynamics (CFD) simulations are employed to analyze the dynamic behavior of the HEX. Three PCM configurations, 15 variations in fin densities, and three paraffin-based PCMs with distinct melting temperatures are considered. The results reveal that the Type II configuration enhances heating time at high set point temperatures (SPTs), while the Type I configuration extends heating time at low SPTs. Increasing the air mass flow rate (AMFR) reduces the overall discharged thermal energy by 18–19 % for Type II and III configurations and by 10 % for the Type I configuration, indicating the lower sensitivity of Type I to AMFR variations. It is also shown that decreasing the PCM domain's fin density extends the heating time at low SPTs. Additionally, using a PCM with a higher melting temperature enhances the heating time at high SPTs and increases latent energy discharge power. Tetracosane demonstrates the highest efficiency at 54.9 % and maximum total discharged energy reaching 112.4 kJ. The findings of this study have significant implications for the development of optimized PCM heat exchangers in various applications, enabling more efficient and impactful thermal management.

Research the Effects of Phase Change Materials on the Properties of Cement

Structural concrete of Mass Concrete of high-rise buildings has a compressive strength usually greater than 35 MPa. It is quite difficult to keep the required Tmax temperature, but the compressive strength and properties of the concrete mix. The phase change materials, when added to the concrete mix, has the effect of lowering the total heat of the mass conctete from 5 ºC to 10 ºC, contributing to reduce the temperature Tmax. At present, in Vietnam, phase change materials are new materials, and there is no research on the effects when used in cement and concrete. The article studies the influence of phase change materials on the properties of cement.

Simulation study of drilling fluid cooling in long horizontal wells based on phase change heat absorption

ABSTRACT The shale gas resources found in deep formations are abundant and represent a crucial area for current and future shale gas development. However, as shale gas exploration and development intensify in China, an increasing number of high-temperature formations are being encountered during drilling, presenting significant challenges to drilling engineering and severely constraining the development of deep shale gas exploration. In this study, the stability of PCM (phase change material) combined with drilling fluid as a coolant was discussed, and the influence of PCM on wellbore temperature field in drilling fluid was considered. A calculation model of temperature field of drilling fluid containing PCM was established, the cooling characteristics of PCM under the influence of different parameters were simulated, and the cooling effect of PCM integrated with drilling fluid on ultra-deep and high-temperature Wells was analyzed. The investigated PCM has a phase change temperature range of 120 ~ 130°C and a latent heat of 264.15 ~ 265.53 kJ/kg. Our results showed that the cooling impact of PCM exhibits an upward trend as the quantity of PCM utilized increases. Assuming the drilling temperature limit is 135°C, after adding 5% PCM to the drilling fluid, the drilling length of the horizontal section increased by approximately 500 m. With 15% PCM added, the horizontal section could be extended by about 1000 m. We conducted a simulation analysis on a well in southern Sichuan, and found that adding 12% PCM had the best cooling effect, reducing the bottom hole temperature by 12.3°C and extending the horizontal section by 700 m. Compared with conventional drilling fluid cooling methods, incorporating PCM as cooling agents within the drilling fluids provided better cooling effects. It effectively addressed the problem of excessive bottom-hole temperatures in deep wells, extended the drilling length of horizontal sections, and prolonged the service life of downhole instruments. Our research lays the groundwork for the future investigation of cooling techniques for high-temperature deep well drilling fluids.

Experimental and numerical investigations on the influence of phase change materials on heat transfer reduction across the roof of a building

ABSTRACT Faced with the problems of increasing energy scarcity and ongoing environmental deterioration, phase change materials (PCM) have attracted a lot of attention recently for improving building energy performance. Utilizing the PCMs in buildings is one of the efficient approaches to reduce the heat penetration into the buildings. In this work, the thermal performance of a building equipped with PCM roof is analyzed and compared with a plain roof building. The uniqueness of this study is to analyze the effect of PCM experimentally and numerically through parametric investigation with different PCMs (HS29 and OM29), encapsulation materials (aluminum and steel) and PCM thickness. The experimental analysis shows that the PCM incorporated roof decreased the inner room temperature of the building by 2°C vis-à-vis plain roof and hence helps reduce the cooling load and enables passive cooling of the building with energy savings. A numerical analysis was carried out using COMSOL and validated with maximum and average errors of 7.43% and 4.87% respectively. The parametric investigation from the validated model indicates that the PCM OM29 is effective compared to HS29 in terms of temperature reduction. The steel encapsulating panels are observed to be better than aluminum at the peak sunshine hours while the aluminum panel is effective for the other periods. It is observed that the increase in PCM thickness augments the reduction in heat transfer while the 6 cm PCM thickness showed a higher temperature reduction by 3.6°C vis-a-vis 2 cm PCM thickness.

Experimental investigation of influence of phase change materials in energy consumption of air-conditioning units and prediction performance evaluation of modified deep neural network model

In this study, the influence of hybrid phase change materials on the energy consumption of air-conditioning units installed to maintain a comfortable temperature inside the testing room was experimentally studied and numerically analyzed. The Paraffin, Halloysite and Ethylene glycol microcapsules were combined to form PHEg filler materials. These PHEg phase change materials were further mixed into a normal Portland cement mortar to prepare 5 different phase change material mortars. Based on the prepared motors, a pair of 1.22 m × 1.22 m × 0.2 m size test specimens were prepared to experiment. After testing the specimens with various outside temperatures, the energy consumed by an air-conditioning unit was reported. There was a 20–22% reduction in energy consumption recorded while testing with phase change material mortar specimens than normal cement mortar. Also, the results proved that the energy consumption of the air-conditioning unit could be reduced further by 10% when the outdoor temperature dropped to below 24 °C. In addition, the performances of prepared samples were predicted using a modified deep neural network model. The developed model accumulated 99.867% accuracy and a maximum of 0.1607 mean absolute error and 0.0172 root mean square error, better than several existing neural network models.

Investigation of continuous pulse current source on the performance of phase change material-thermoelectric cooler system

In this particle, the influence of phase change materials (PCM) on the property of thermoelectric cooler (TEC) is studied by numerical simulation. The heat sink integrated with PCM is placed on the hot side of TEC to reduce the fluctuation of temperature under a continuous pulse current source. The performance of a single-layer PCM-TEC system with that of a single TEC system under continuous pulse current source is firstly compared. Based on this, the effects of current source type, PCM layer, pulse width, cooling load and pulse amplitude on the cooling performance of TEC are investigated in depth. The results show that, compared to a single TEC system, PCM is able to considerably enhance the cooling performance of the TEC during the phase transition period. Besides, increasing PCM layer or decreasing cooling load improves the phase change interval, which increases threefold when the cooling load increases from 0.02 W to 0.06 W. In addition, it is found that lower temperature can be achieved by increasing pulse width or pulse amplitude.

Phase change materials for energy efficiency in building components – Overview

Energy demand in the building particularly in summer during peak hours due to outdoor climate and lack of sufficient high thermal mass construction materials. Advanced materials are required to reduce the recurring energy demand of buildings. This peak hour energy demand can be significantly reduced by using phase change materials (PCM). These PCMs may be incorporated into building components/ products in various ways. In this overview, the recent advances in the field of using different types of PCMs, parameters to be consider for building components, encapsulation of PCMs and influence of PCMs on thermal and mechanical properties of construction materials are briefly discussed. Importantly, behaviour of MPCM in building components is concisely elaborated in effective way.

Influence of phase change materials on thermal comfort, greenhouse gas emissions, and potential indoor air quality issues across different climatic regions: A critical review

Influence of phase change materials on thermal comfort, greenhouse gas emissions, and potential indoor air quality issues across different climatic regions: A critical review

Multi-scale analysis of mechanical and thermal behaviour of mortars incorporating phase change materials

This study presents the influence of phase change materials (PCMs) on the cyclic behaviour of mortars. A multi-scale analysis comprising mechanical and thermal tests was used to explain the phenomena involved. Mechanical and thermal cyclic tests were performed on four configurations of mortars containing 0%, 5%, 8%, and 10% of PCMs. It was revealed that mechanical cyclic loading did not significantly affect the resistance of mortars contrary to thermal solicitations. Indeed, it was shown that the incorporation of PCMs improved the thermal capacity of the mortars. However, severe degradation of the heat capacity and enthalpy was noticed after the temperature cycles. The physicochemical characterisation tests confirmed a moderate structural degradation, which primarily occurred in the initial cycles. Regarding the thermal cycles, scanning electron microscopy (SEM) and calorimetry characterisations corroborated the leakage of PCMs into the cement matrix, which was responsible for the degradation of latent heat. Finally, it was observed that the PCM–mortars resisted mechanical cyclic solicitations, at least up to 1000 cycles; however, they were still sensitive to repeated variations in temperature.

Influence of phase change material (PCM) parameters on the thermal performance of lightweight building walls with different thermal resistances

Phase-change materials (PCM) can effectively improve the thermal performance of lightweight building walls (LBW), but their contribution efficiency is related to PCM parameters and the thermal resistance of the original walls ( R wt ). Therefore, a heat transfer model of LBW integrated with PCM was built and validated in this paper, and the influence rules and contribution efficiency of PCM parameters on the thermal performance of LBW with different R wt were analyzed and evaluated by numerical simulation. The results show that: (1) The suitable phase-transition temperature is more influenced by the PCM location and less by R wt , and the middle of wall and 22–32 °C is the best choice for PCM; (2) The PCM parameter values are not proportional to the improvement of thermal performance and its influences are more noticeable as the R wt decreased, and their optimal values and its contribution efficiency are diminished with R wt is boosted; (3) The PCM contribution efficiency is reduced by 56.61%(attenuation rate), −34.3%(delay time), 58.31%(peak heat flux) and 61.78%(average heat flux) as the R wt [(m 2 ·K)/W] is increased from 2.0 to 5.0 under the suitable PCM parameters. The findings provide data support and theoretical reference for the application of PCM in different types of lightweight buildings.

Influence of Phase Change Material Physicochemical Properties on the Optimum Fin Structure in Charging Enhancement

Orthogonal fins made of a vertical and a horizontal fin shorten total charging time and enhance average charging rate of lowly conductive phase change materials (PCMs) such as paraffin wax. An optimum dimension of orthogonal fins exists during charging of paraffin wax under top heating. The optimum dimension is represented by the optimum relative distance. The relative distance d/lv is defined as the ratio of the distance between horizontal fin and bottom wall of enclosure to length of vertical fin. However, the physicochemical properties of PCMs are variant in practical. Their influences on this optimum relative distance of orthogonal fins are not conducted. In current investigation, the investigations on influence of PCMs’ physicochemical properties on the optimum relative distance of orthogonal fins are numerically carried out. Influences of PCMs’ physicochemical properties including thermal conductivity, thermal expansion coefficient and viscosity on the optimum relative distance of the orthogonal fins are analysed. Results demonstrate that these physicochemical properties significantly influence the optimum relative distances. The optimum relative distance decreases from ~0.1633 to ~0.1020 when thermal conductivity increases from 0.1 W·m-1·K-1 to 1.5 W·m-1·K-1. When thermal expansion coefficient of PCM increases from 0.0001 K-1 to 0.005 K-1, the corresponding optimum relative distance decreases from ~0.1877 to ~0.0816. When viscosity of the liquid PCMs increases from 0.2 mPa·s to 80 mPa·s, the optimum relative distance of orthogonal fins increases from ~0.1224 to ~0.2245. The results supply an effective guideline to design an optimum orthogonally structured fins to enhance the average charging rate of organic PCMs with random physicochemical properties.

The effect of phase change materials on cement hydrate in steam-cured cement-based materials

The application of phase change materials (PCMs) in steam-cured cement-based materials is very interesting, and a good improvement effect has been achieved in the water resistance of specimens. However, there are few studies on the interaction between PCMs and steam-cured cement-based materials. The influence of PCM, including lauric acid (LA), polyethylene glycol (PEG4000) and paraffin (P-58) on the hydration products of steam-cured cement paste were explored in this study. Calcium laurate is synthesized from lauric acid and calcium hydroxide in atmospheric water medium without additives to facilitate analysis the impact of LA on hydration products. The physical and chemical interactions occurring in the PCMs modified cement pastes were investigated using thermal gravimetric analyzer (TG) and Fourier transform infrared spectrometer (FTIR). The type and morphology of hydration products were studied using X-ray diffraction (XRD), Scanning electron microscope (SEM) and Energy Dispersive Spectroscopy (EDS). The results show that pure calcium laurate is synthesized, and calcium laurate has only low calcium content and free acid. The P-58 evaporates during the thermal decomposition of samples. The addition of P-58 delayed the decomposition of calcium hydroxide. There is no new product formed in the steam-cured cement pastes containing P-58. The addition of LA and PEG4000 into the steam-cured cement pastes promotes the formation of organic salt-carboxylate. The carboxylate can be decomposed into carbonate phase at high temperature. In the current investigated area, the addition of LA, PEG4000 or P-58 has almost no influence on the quantity of cement hydration products and phase compositions of steam-cured cement pastes.

Influence of phase change material on concrete behavior for construction 3D printing

Large-scale construction 3D printing (C3DP), which is also known as green building construction is an innovative method that can save time, materials, and labor costs. The suitable printing materials should have the properties of good fluidity, excellent early strength, appropriate setting time, suitable viscosity, and cost-effectiveness. Among the main concerns of the construction 3D printing, the clogging of the material induced by premature setting and poor fluidity of the concrete is a significant one. It hinders the pumping capacity of concrete materials from the mixer to the extruder and reduces the overall efficiency of the C3DP process. The existing literature has proposed a variety of materials for C3DP, but there is still no standard information on the material selection. Therefore, it is necessary to solve the problem of material clogging while obtaining the above-mentioned characteristics suitable for printing materials. In the present study, the suitable printing properties for C3DP material were obtained to solve the clogging problem. The composition based on industrial solid waste was used to prepare this material. The use of this material in C3DP was proved to be cost-effective. Suitable setting time (33 min), good fluidity (181 mm), and excellent compressive strength (10.4 MPa and 78.2 MPa for 2 h and 28 days, respectively) were realized. These suitable properties were obtained by adding the phase change material (PCM) at different temperatures. In addition, due to the phase change characteristics, PCM has been proven to effectively solve the clogging problem of material. Furthermore, optimized material was used to print 3D structures with different shapes. We believe that this work can provide innovative ideas for the promotion of green building construction and the production of high-value products.

Investigation of the thermal response of PHC energy pile backfilled with phase change material

The influence of phase change material (PCM) backfill material within precast high-strength concrete (PHC) pile on the thermal behavior of the energy pile is rarely studied. This paper develops a numerical model to investigate the thermal response of the PHC energy pile backfilled with PCM. The results show that the higher latent heat and thermal conductivity of PCM backfill material inside the PHC pile can effectively improve the heat transfer capacity of PHC energy pile. Besides, the intermittent operation mode is beneficial to the enhancement in heat transfer behavior of PCM-backfilled PHC energy pile. For PCM and improved PCM backfill material, the heat exchange rates of PHC energy pile at 6:18 intermittent mode rise by 57.11% and 64.06% compared with continuous mode. Finally, because the improved PCM backfill material has higher latent heat and thermal conductivity, the ground temperature around the improved PCM-backfilled PHC energy pile shows a faster growth trend than PCM backfill material. Additionally, the intermittent operation mode produces a slower growth rate of ground temperature around the pile.

Experimental investigation on the influence of phase change material on the output performance of thermoelectric generator

Thermoelectric generators (TEGs) can convert heat into electricity directly. However, the thermal boundary conditions are intermittent and high temperature in most TEG systems. Therefore, thermal management of TEG systems is of great significance. It is an efficient technology to use phase change material (PCM) for thermal management of the TEG systems. PCM is applied to hot side of TEG in this study, and the phase change material-thermoelectric generation (PCM-TEG) system is set up. For the purpose of exploring the effect of the PCM on the output performance of TEG, the common TEG system is established to compare with PCM-TEG system. Furthermore, the effect of the heat transfer characteristics of PCM on TEG output performance is investigated and discussed in detail under different pulse transient thermal boundary conditions. Experimental results show that PCM can reduce the temperature fluctuation to protect TEG and extend the temperature difference operation time. The PCM of solid state, solid-liquid coexistence state and liquid state have different effects on reducing the temperature fluctuation. Besides, the PCM-TEG system cannot provide the peak output power provided by the common TEG system, but it is still beneficial to provide a stable output power.

Role of BIM and energy simulation tools in designing zero-net energy homes

Purpose The purpose of this study is to design a zero-energy home, which is known to be capable of balancing its own energy production and consumption close to zero. Development of low-energy homes and zero-net energy houses (ZEHs) is vital to move toward energy efficiency and sustainability in the built environment. To achieve zero or low energy targets in homes, it is essential to use the design process that minimizes the need for active mechanical systems. Design/methodology/approach The methodology discussed in this paper consists of an interfacing building information modeling (BIM) tool and a simulation software to determine the potential influence of phase change materials on designing zero-net energy homes. Findings BIM plays a key role in advancing methods for architects and designers to communicate through a common software platform, analyze energy performance through all stages of the design and construction process and make decisions for improving energy efficiency in the built environment. Originality/value This paper reviews the literature relevant to the role of BIM in helping energy simulation for the performance of residential homes to more advanced levels and in modeling the integrated design process of ZEHs.

Effect of expanded graphite/polyethylene glycol composite phase change material (EP-CPCM) on thermal and pavement performance of asphalt mixture

The application of phase change materials (PCMs) to the temperature regulation of asphalt pavements has recently become a hot topic of research. At the same time, studies concerning the influence of PCMs on the thermal and pavement performance of asphalt mixtures are still rarely available. The primary objective of this study was to reveal the effect of an expanded graphite/polyethylene glycol composite phase change material (EP-CPCM) on the thermal and pavement performance of asphalt mixtures. EP-CPCM was incorporated into an AC-13 asphalt mixture at various dosages. First, the thermal performance, including thermal constants and thermal regulation effects of the EP-CPCM-modified asphalt mixtures was evaluated, followed by an investigation of the pavement performance in terms of rutting and cracking resistance, moisture stability, and fatigue resistance. The results indicate that by reducing the heating and cooling rates as well as extending the heating and cooling times, EP-CPCM can regulate the temperature of asphalt pavements. The thermal balance inside the pavement and heat exchange between pavement and the ambient environment also improved. The rutting resistance and cracking resistance of asphalt mixtures were enhanced, mainly when the dosage of EP-CPCM was limited. However, the adverse effects of EP-CPCM on the moisture stability under hot water conditions, freeze-thaw conditions, fatigue life, and stress sensitivity gradually emerged when the dosage of EP-CPCM increased.

Experimental investigation on the influence of phase change materials on properties and pore structure of steam-cured mortar

Steam-cured concrete with high early strength has been widely applied in high-speed railway. However, heat damage caused by the steam curing process brings adverse effects on the pore structure and durability of steam-cured concrete. It has been found that phase change materials (PCMs) help improve the durability of cement-based materials. Therefore, the influences of two PCMs on the strength, water absorption, and microstructure of steam-cured mortar are discussed in this study. Two PCMs used include pure paraffin and a composite phase change material composed of porous diatomite and paraffin (D/P). The results show that the addition of appropriate PCMs does not significantly reduce the strength of steam-cured mortar. The addition of a small amount of PCMs shows little influence on the pore structure of steam-cured mortar but effective in improving the water-penetration resistance. This is partially attributed to the improvement of hydrophobic characteristics in the pores, resulting from the adhesion of hydrophobic PCMs on the pores during the steam curing. Compared with specimens containing pure paraffin, the pore structure of specimens containing D/P is refined, resulting in higher compressive strength. This may be due to the uniform distribution of small particles D/P in the specimen and the pozzolanic reaction of diatomite in D/P. The use of suitable phase change materials will be helpful to improve the durability of steam-cured concrete.