Phase Change Temperature Range Research Articles

An innovative PCM-modified lining system for energy tunnel: From concept to numerical investigations

The rich geothermal stored in rock mass would result in high temperature to tunnels. This not only makes condition worse to workers, but also wastes geothermal energy and increases cost to adjust the internal environmental temperature. This motivates the present feasibility study on an innovative PCM-modified lining system of conventional energy tunnel, which generally makes use of ground source heat pump (GSHP). That is, the PCM-modified concrete regulates the thermal properties of tunnel linings installed with pipe loops of GSHP. To verify the concept of the new system, a finite element model (FEM) describing it is established, based on a case of high geothermal tunnel. Simulation of the heat conducting process of tunnel linings starting from hydration of cement during cast-in-place concrete, thermal conductivity from surrounding rock mass, circulating of GSHP, phase change within the PCM-modified linings, and boundary effect since ventilation are considered in the modeling. The results demonstrate that the new system would mitigate the level of thermal discomforts during construction stage, and it can improve the stability and efficiency in energy extraction in operation stage. Parametric study on the GSHP with PCM-modified linings gives that the better heat reduction performance can be obtained with the smaller intermittent ratio (IR) of GSHP, smaller temperature range of phase change, and larger latent heat, and higher exchanger rate can be obtained with the larger IR and larger latent heat.

Preparation and characterization of eicosane-paraffin/expanded graphite/polyurethane as form-stable composite phase change materials with wide phase change temperature range

Phase change materials (PCMs) with wide phase change temperature range, high latent heat, good thermal conductivity, and shape stability are essential for applications such as solar energy conservation and thermal management of electronic devices. Form-stable composite PCMs (FSCPCMs) with a broad phase change temperature range of 18–65 °C were successfully developed by using a mixture of eicosane and paraffin mixture along with cross-linking polyurethane as PCM, expanded graphite as thermally conductive filler and supporting material. The prepared FSCPCMs demonstrated excellent thermal stability and thermal conductivity with a latent heat up to 142.5 J/g. In conclusion, the synthesized FSCPCMs exhibit promising potential for practical applications in thermal energy storage.

Usage of Microencapsulated Phase-Change Materials to Improve the Insulating Parameters of the Walls of Refrigerated Trailers

Climate change is forcing action to reduce energy consumption and greenhouse gas emissions. An extremely important area of high-polluting energy consumption is material transport and, within this, the transport of chilled goods, including deep-frozen goods, is an important contributor. Phase change materials (PCMs) can have an important role in reducing energy consumption for the transport of chilled goods, but the current state of knowledge is not sufficient to bring the solution into popular use. This article includes a study of the effect of implementing microencapsulated PCM (mPCM) in polyurethane foam (PU) on the insulation performance of refrigerated trailer walls in low-temperature transport. In this research, mPCM was used, characterised by a phase-change heat in the range of 170–195 kJkg and a phase change temperature in the range from −10 °C to −9 °C. The studies performed show the potential of using mPCMs to improve the insulation performance of the walls of refrigerated trailers. Containing mPCM in the amount of 5.0% wt. placed throughout the entire volume of the wall can improve thermal conductivity of the wall for up to 15% in peak and 4.5% (0.2792 Wm2K without mPCM and 0.2665 Wm2K with mPCM) in the phase change temperature range. Out of the range of phase change temperatures, the thermal conductivity of the wall with mPCM is worse for 2.72% than in walls without PCM. Problems that need to be tackled were also identified, before the solution can be put into everyday use, i.e., finding the technology to increase the proportion of mPCMs relative to PU.

Numerical and three-factor design investigation for melting process of phase-change spherical capsules in a solar thermal energy storage system

The application of spherical phase-change capsules in solar thermal energy storage systems (STESS) can enhance the sustainability and stability of energy output in solar energy utilization, making it a recent research hotspot. Nonetheless, the influence of neglecting three-dimensional effects through structural simplification on the phase-change process and the criteria for selecting the mushy zone constant in numerical studies are still not well-defined. In this context, a detailed analysis is conducted to investigate the variations in liquid fraction, temperature, flow field, and the time required for complete PCM melting caused by the structural simplification method. Subsequently, a three-factor design analysis is performed on parameters including spherical radius (R), mushy zone constant (Amush) and phase-change temperature range (ΔT) with the aim of establishing a rational basis for selecting the mushy zone constant. Results show that the simplification of the 3D spherical encapsulation structure into a two-dimensional (2D) circular encapsulation structure introduces notable discrepancies in the PCM melting process. In contrast to the 2D circular encapsulation structure, the 3D spherical encapsulation structure demonstrates a reduction in the time required for complete PCM melting by 23 % to 36 %. The influence of simplifying the 3D spherical encapsulation structure into a 2D axisymmetric encapsulation configuration on the numerical simulation of the PCM melting process becomes more pronounced with the increase of R. For the 3D spherical encapsulation structure, the hierarchy of significance regarding the factors influencing the PCM melting process manifests in the sequence: R, Amush, (R × Amush), and ΔT. Furthermore, the formulated correlation based on the aforementioned four factors enables precise prediction of the time required for complete PCM melting within the 3D spherical encapsulation structure and offers a foundation for selecting the appropriate Amush value in numerical simulation. The present work contributes novel insights into the accuracy and rationality of numerical simulations for phase-change processes in the STESS.

Preparation, characterisation and property modification of a calcium chloride hexahydrate phase change material slurry with additives for thermal energy transportation

Efficient thermal energy distribution and rational energy management are effective solutions to address the significant and fast-ascending energy consumption in building heating, ventilation, and air conditioning (HVAC). Phase change material (PCM) slurries with excellent thermal energy transportation and storage characteristics have been recognised as promising secondary refrigerants to simultaneously facilitate efficient heat/cold transport and effective thermal energy storage in air conditioning systems. Among various PCM slurries, salt hydrate PCM slurries have attracted increasing attention in recent years due to their many inherent advantages. This paper presented the preparation, characterisation, and property modification of a CaCl2·6H2O slurry based on a methodology proposed for optimal salt hydrate PCM slurry development. Theoretical modelling was first carried out to assess the availability of salt hydrate PCM slurries based on the phase diagram and solid fraction, followed by a series of property measurements to reveal the mechanisms and address the problems behind the phase transition, crystal particle morphology, stability and rheologic characteristics, using nucleating agents, surfactants and stabilisers. It was found that the salt hydrate PCM slurry developed provides a unit volume enthalpy twice that of water over the phase change temperature range of 5°C, together with acceptable fluidity. The results also showed that the PCM particle size can be well controlled, and the slurry can be stabilised, with the assistance of surfactants and stabilisers. Compared to other types of PCM slurries, the proposed salt hydrate PCM slurry has the advantages of being cost-effectiveness, easy preparation, adjustable phase change temperature, etc., which is promising to facilitate energy saving and rationalisation in building HVAC.

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In high-energy-demand regions, such as the Arctic, the building sector is focused on reducing the carbon footprint and mitigating environmental impact. To achieve this, phase change materials (PCMs) are being investigated for thermal energy storage due to their high latent heat of fusion. However, their limited applications arise from poor thermal conductivity. In addressing this issue, the research delves into the preparation and characterization of nano-PCMs. These materials, synthesized in a laboratory setting, exhibit enhanced thermal performance compared to pure PCMs, attributed to the incorporation of nanoparticles in the material composition. Therefore, in the study, three paraffins with different melting temperatures (10, 15 and 18 °C) are modified by incorporating titanium oxide at various concentrations (0.05, 0.1, 0.2 and 0.5 mass%). Thermal conductivity and latent heat capacity measurements were undertaken using a thermal conductivity measuring apparatus and differential scanning calorimetry, respectively. The aim was to evaluate the enhanced performance of the modified PCMs in comparison with pure PCMs and to assess their suitability for cold climate regions. Results showed that nanoparticle incorporation increased thermal conductivity by up to 37%, albeit with a slight reduction in latent heat capacity of up to 12%. Among the samples, RT18 exhibited the most significant improvement in thermal conductivity, while RT10 experienced a minor decrease in enthalpy values. Ultimately, RT10 was identified as the optimal PCM option for cold climates, as its phase change temperature range aligns with the outdoor temperatures in the Arctic.

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.

Advancements in Phase Change Materials in Asphalt Pavements for Mitigation of Urban Heat Island Effect: Bibliometric Analysis and Systematic Review.

This research presents a dual-pronged bibliometric and systematic review of the integration of phase change materials (PCM) in asphalt pavements to counteract the urban heat island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt research, highlighting a marked rise in the number of publications between 2019 and 2022. Notably, Chang'an University in China has emerged as a leading contributor. The systematic review addresses key questions like optimal PCM types for UHI effect mitigation, strategies for PCM leakage prevention in asphalt, and effects on mechanical properties. The findings identify polyethylene glycols (PEGs), especially PEG2000 and PEG4000, as prevailing PCM due to their wide phase-change temperature range and significant enthalpy during phase transitions. While including PCM can modify asphalt's mechanical attributes, such mixtures typically stay within performance norms. This review emphasises the potential of PCM in urban heat management and the need for further research to achieve optimal thermal and mechanical balance.

Numerical simulation on jet impingement heat transfer with microcapsule phase change material suspension: Single jet and array jet

The heat transfers on the single and array jet impingement with microcapsule phase change material (MEPCM) suspension are numerically investigated. The equivalent heat capacity method and DPM model are employed to treat the latent heat absorption and motion of the MEPCM particles in suspension, respectively, as well as the VOF method for tracking the free surface from suspension to air. The results show that the latent heat absorption and disturbance effect of the MEPCM particles can significantly improve the heat transfer of the suspension compared to the water. There exists an optimal jet distance at ΔL/D = 4.2 and an optimal suspension concentration at ηp = 5% to achieve the optimal heat transfer. The jet inlet temperature has a favourable range for the heat transfer enhancement, −0.83 <θj < 0.39, which is lower than the phase change temperature range of MEPCM particles. Compared to single jet, the array jet may provide a better heat transfer although the cross-flow between neighboring jets weakens the heat transfer of central jet column. Both of hole number and hole spacing for array nozzle have a non-monotonic effect on the heat transfer, with the optimums at N = 19 and S/D = 7, respectively.

A review on thermal energy storage with eutectic phase change materials: Fundamentals and applications

The storage and use of thermal energy have gained increasing attention from various countries. Phase change materials (PCMs) are commonly used in thermal energy storage (TES) applications due to their high latent heat. More than a hundred single-component PCMs have been reported, each with a specific phase change temperature. In addition to single-component PCMs, eutectic phase change materials (EPCMs) are also used in TES. EPCMs are homogeneous mixtures of binary, ternary, or multiple-component PCMs that melt at a unique temperature lower than the melting point of any of the constituents. Compared to single-component PCMs, EPCMs demonstrate superior performance in TES applications, with a broader phase change temperature range and improved phase stability. This review provides an overview of over 250 organic/inorganic EPCMs from eutectic theory, material classification, thermophysical properties, preparation and characterization methods, techniques for thermal performance improvement, and applications. The review also concludes with a discussion of future prospects and findings that EPCMs can enhance heat storage density and thermal stability when compared to single-component PCMs. This information serves as a reference for the development of heat storage materials with improved thermal physical properties in the future. Overall, this review provides a comprehensive summary of EPCMs from their fundamentals to applications.

Preparation and characteristics of paraffin/silica aerogel composite phase-change materials and their application to cement

In this study, microencapsulated paraffin/silica aerogel composite phase-change materials (MPCMs) were developed and incorporated into cement to impart heat storage/release capabilities. First, the hydrophilically modified MPCMs were subjected to a leakage test. Using a simple stirring method, the composite with an aerogel: paraffin mass ratio of 22:78 was demonstrated to have the best adsorption capacity. Transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction analyses revealed that the paraffin was stable and physically encapsulated by the aerogel. The differential scanning calorimetry results showed that the encapsulated MPCMs had a fusion latent enthalpy of 94.45 J/g and phase-change temperature range of 20.8–34.4 ℃. The enthalpy was reduced by only 3.87% after 1000 freezing–thawing cycles. In the second part of the experiment, heat-storage cement (HSC) specimens were prepared to investigate the effect of MPCMs modified with silane coupling agents. The proportion of MPCMs and curing temperature were varied, and the effects of these variations on the compressive strengths of HSC stones were investigated. The compressive strength of the HSC samples was improved by adding multiwall carbon nanotubes (MWCNTs) to paraffin to form paraffin/aerogel composite MWCNT micro-encapsulated phase-change materials (CMPCMs). The results show that adding 1.53 wt% MWCNTs increases the thermal conductivity by 50.6% and refines the pore size and strength of the HSC stone. Furthermore, the 7-day strength of the HSC stone increased to 8.6 MPa by adding MWCNTs to 30 wt% modified CMPCM, meeting the requirement standard. Cement hydration calorimetry, performed using a TAM AIR isothermal calorimeter, revealed that MPCMs prolong the induction period of cement hydration, reduce the rate during the acceleration period of cement hydration, and absorb the heat of hydration. Moreover, the thermal regulation behaviour of 10 mm thick HSC plates was tested. The highest temperature difference was determined to be 2.36 ℃ and 1.92 ℃ during the heating and cooling processes, respectively, compared with that of plain cement plate, at the same time. Therefore, HSC panels have potential applications in building thermal management.

A route of polyethylene glycol-based phase change heat storage wood with AlN as the thermal conductive filler

Wood is a great natural material with good energy storage and temperature adjustment for the energy crisis. In this study, wood was delignified, and the PEG-based eutectic polymer (PGMA) was impregnated into the delignified wood, and styrene (SM) grafted AlN was selected as thermal conductive filler to synthesize a stable phase change heat storage wood. The result shows that the styrene (SM) polymerized on the surface of AlN to form polystyrene (PS), and the dispersion of AlN was enhanced. The thermal stability and loss resistance of PCES-Wood are improved for the penetration of PS-AlN into the cavities, which is attributed to the PS-AlN playing a “limiting” role in the crystallization of PGMA. When the content of PS-AlN is 6%, the thermal conductivity of PCES-Wood reaches 0.5148 W/(m·K). 4% PS-AlN-PCES@Balsa has the lowest undercooling and heat loss rate, and the melting enthalpy and solidification enthalpy reach 125.60 J/g and 120.30 J/g, respectively. The phase change temperature range is between 19.59 and 33.87 °C, which is in the comfortable temperature range for humans. Under the illumination of the simulated solar light source, the surface temperature of PS-AlN-PCES@Balsa rises rapidly and shows a lasting heat storage capacity at low temperatures compared with the original wood. After 200 cold and hot cycle tests, the phase change enthalpy of PS-AlN-PCES@Balsa is still high, and there is a slight leakage phenomenon. The phase change wood prepared in this study shows that it is a potential material to store and release solar energy in practical applications.

Thermal and structural behavior of thermal inertia-reinforced mortars for building envelope applications

Phase-change materials (PCM) are applicable to various building components and systems. In this study, a thermal storage mortar is manufactured by mixing thermal storage aggregate (TSAs) synthesized using a vacuum-impregnating PCM with blast furnace slag. In the scanning electron microscopy analysis, the TSAs were mixed and dispersed relatively uniformly in the thermal storage mortar and maintained their physical shape. From the differential scanning calorimetry result, the theoretical latent heat amounts of the thermal storage mortar mixed with 10, 20, and 30 wt% TSA were 3.27, 6.21, and 8.86 J/g for both heating and cooling, respectively. The cumulative specific heat of the thermal storage mortar was 160.95 J/g when the temperature increased from 0 °C to 80 °C. Results of the thermal conductivity analysis showed that when the TSA content for the thermal storage mortar increased to 20 wt%, the thermal conductivity increased because of the effect of blast furnace slag. In the structural analysis, the reference mortar and the thermal storage mortar containing 10 wt% TSAs exhibited brittle fracture, whereas the thermal storage mortar containing 20 or 30 wt% TSA showed ductile fracture. Results of the dynamic heat transfer analysis showed that the upper and lower surfaces of the thermal storage mortar indicated a peak temperature reduction and time lag in the phase-change temperature range during heating and free cooling.

Inversion of extinction coefficient and refractive index of variable transparency solid–solid phase change material based on a hybrid model under real climatic conditions

The application of phase change materials (PCMs) in transparent building envelopes has received extensive attention. However, most of the studies have simplified the optical parameters of the PCMs in their models. Because the temperature of PCMs cannot be controlled when using the spectrophotometer, it is difficult to measure the changing trend of optical parameters versus temperature. In this study, an inverse approach was developed for the first time, based on a hybrid model, to fit the accurate function expressions between the extinction coefficient and the refractive index of PCM and temperature. The hybrid model was a combination of experimental data-driven, mathematical models, and multi-objective optimization. Firstly, a test platform of the variable transparency solid–solid PCM (VTSS-PCM) window was constructed and tested last for a year to collect the datasets. Secondly, the photo-thermal coupling model of the window was established, in which the hysteresis and the total internal reflection phenomena were considered. Then, taking the unknown coefficients in the function expressions as decision variables, a bi-objective optimization model was built, based on two error statistics of experimental values and simulated values, and solved by genetic algorithm. Finally, the inversion dataset and validation dataset were used to prove the reliability of the inversion results. The results showed that the refractive index and extinction coefficient of the VTSS-PCM were 1.11 and 25.73 m−1 in the transparent phase, and 5.33 and 152.82 m−1 in the opaque phase. Within the phase change temperature range, the function expressions between the refractive index and extinction coefficient and the temperature were obtained respectively. The verification results showed that the function curves obtained by inversion were reliable. No matter whether the inversion dataset or validation dataset was used as input, the values of RMSE and CV(RMSE) met the ASHRAE Guidelines. The inversion method is meaningful to get the optical parameters of PCMs, to accurately evaluate the performance of PCM-built envelope.

Performance and evaluation models for different structural types of asphalt mixture using shape-stabilized phase change material

The vulnerability of road infrastructure to changes in environmental conditions has received increasingly widespread attention. The ability to absorb and release latent heat using phase change material (PCM) can confer ability to store thermal energy in asphalt pavements. This mitigats the effects of environmental fluctuations on pavement performance. In this study, the influences of PPGC-PCM, a shape-stabilized phase change material, on the mechanical properties, moisture resistance, high temperature stability and low temperature crack resistance of different structural types of asphalt mixture (AC-13, SMA-13) were discussed. A test platform of unsteady thermal conductivity was established to analyze the effects of PPGC-PCM on the thermal conductivity and specific heat capacity of asphalt mixture with different structure types. An evaluation model was constructed using response surface methodology (RSM), and the impacts of PPGC-PCM and gradation type on the comprehensive performance of asphalt mixture were analyzed. The results showed that the addition of PPGC can improve the thermal insulation performance and heat storage efficiency of asphalt mixture. With the increase of PPGC-PCM addition, the mechanical properties and moisture resistance of the asphalt mixture first improved and then deteriorated. Compared with the control group, the Marshall stability and residual stability of the AC-13 and SMA-13 PPGC-PCM asphalt mixture could be improved by 3.7%, 3.3% and 6.7%, 7.5%, respectively. Addition of PPGC-PCM could obviously improve the insulation performance and heat storage efficiency of the asphalt mixture. The specific heat capacity of asphalt mixture increased significantly in the PPGC-PCM phase change temperature range. However, PPGC-PCM had negative effects on the long-term high-temperature stability and low-temperature cracking strength of asphalt mixture. For different structural types, the effect of PPGC-PCM addition on the mechanical and thermomechanical properties of asphalt mixtures was more pronounced as the continuity of gradation increased. Continuous-graded asphalt mixture can achieve better performance with lower PPGC-PCM addition, while gap-graded asphalt mixture can accommodate more PPGC-PCM particles and has better comprehensive performance. According to the performance evaluation model, the recommended additions of PPGC-PCM in AC-13 and SMA-13 asphalt mixture were 5.5%∼8.5% and 7.5%∼10.5%, respectively. Engineering application proved that when PPGC-PCM was added at 7.5% in asphalt pavement, the maximum temperature of the pavement in summer was reduced by 8.9 ℃ with a time delay of 60 min compared to ordinary asphalt pavement. In winter, the experimental road section showed the potential to melt the snow more efficiently.

A novel numerical approach for measuring phase change temperature range of Phase Change Material in real building conditions

Phase change materials (PCMs) integrated into the building envelope offer a significant interest in regulating indoor temperatures. They allow them to approach, reach or maintain thermal comfort conditions for the occupants. The efficiency of the PCM depends on its intrinsic parameters, such as latent heat or phase change times. These parameters are usually obtained from expensive differential scanning calorimetry (DSC) or Heat Flux Meter Apparatus (HFMA) measurements. This paper proposes an innovative numerical method to provide the same information from simple measurements of temperature and heat flux at their surface. The Latent Heat Detection Method (LHDM) allows the detection of the duration of the transition zones and calculates the latent heat of the phase change. The LHDM method is applied to the annual data of a full-scale platform, and a PCM performance indicator is proposed. Comparing the DSC results allows concluding of the accuracy of the proposed method. The maximum associated relative errors remained below 6%, with an average relative error close to 2.5% for the onset temperatures and 1.61% for the endset temperatures. These results offer promising prospects for increasing the accessibility of experimental PCM research.

A novel petal-type battery thermal management system with dual phase change materials

Phase change material (PCM) cooling is a prominent approach for battery thermal management. However, its application scenario is severely limited by the narrow range of phase change temperature. When the temperature of PCM does not reach the phase change temperature range, it is either a pure thermal conductive material or a completely molten liquid material, neither of which can play a role in battery thermal management. The present study proposes a novel petal-type battery thermal management system (BTMS) with dual PCMs, which has significantly enhanced the environmental adaptability of the battery based on PCM cooling. The thermal performance of the BTMS at different ambient temperatures and discharge rates is investigated by numerical simulation methods. The results show that when the battery is discharged at 1∼5C at an ambient temperature of 25°C, the maximum battery temperature (Tmax) is 29.87°C, 32.89°C, 34.69°C, 36.84°C, and 39.41°C, respectively. When the battery is discharged at 2C at 20°C, 30°C and 40°C, the Tmax is 30.49°C, 34.16°C and 43.70°C, respectively. Compared with the other two conventional BTMSs using a single type of PCM, the thermal performance and environmental adaptability of the proposed BTMS is the best under the three typical ambient temperatures. Furthermore, the above BTMS is optimized using fin-reinforced heat transfer technology in this paper. Compared to the BTMS without fins, the optimized solution 2 with asymmetric fin arrangement reduces the maximum temperature difference (ΔTmax) by 5.53% and 29.19% and the maximum temperature rise (ΔTmrise) by 36.15% and 42.76% at ambient temperatures of 30°C and 40°C.

Development of a new pumice block with phase change material as a building envelope component

Developed lightweight components of building envelope to improve thermal mass of the building has a crucial role in building sector. There are many studies on this topic around the world. In terms of sustainability, each country focuses on using own local resources and reserves and try to find economic-sustainable solutions. In this context, when examined resources and reserves of our country, it is seen that ranks first in many material reserves. Especially, it is important that Turkey is the second rank in pumice reserves. Pumice is a easily obtainable, healthy economic and lightweight building material. In the literature, it is not found a study improved the thermal mass of the pumice block, which is a lightweight building envelope component. For this reason, this study aims on the production of a new pumice block with phase change material (PCM) as a lightweight building envelope component. PCM improves thermal mass by means of thermal energy storage. The measurement of the thermal mass and physical properties of the building envelope component obtained by adding the phase change material into pumice and discussing the usability of this component in building envelope is a valuable contribution to literature. For this study, four pumice block sample were produced. One of this was reference pumice block without PCM. Others were pumice blocks with PCM at ratios of 5 %, 10 % and 15 %. PCM using block samples is paraffin-based. In the laboratory conditions, the thermal conductivity, specific heat capacity and latent heats of the all samples were measured. Then, using obtained experimental data, an energy simulation is realized to analyze effects on building energy loads of these samples. DesignBuilder was used as energy simulation software and simulations were made on a hypothetical building. In last, the effect of pumice blocks with PCM on the time delay and indoor temperature fluctuations were investigated. In the result of the study, PCM pumice blocks with phase change temperature range at indoor comfort temperatures have been observed to improved up to 6 % in their thermal conductivity and up to 75 % in their specific heat capacity. In hot-humid climates, it is clear that they can provide efficiencies varying between 2 and 7 % during a whole year. Due to their latent heat, it has been observed that they can provide an average of 30 % increase in wall time delay, an approximately 25 % improvement in the effect of indoor temperature fluctuations, and an average of 1.5 °C decrease in indoor maximum temperature.

Study on Temperature Control and Anti-icing Performance of Asphalt Pavement Based on Composite Phase Change Material with Wide Phase Change Interval

To improve the temperature regulation effect of phase change materials on asphalt pavement, phase change materials A and B were prepared for the optimal phase change temperature range of anti-condensation ice and snow melting at -5°C~5°C in this paper. According to the phase change temperature range of phase change materials A and B, the phase change material composite optimization temperature regulation performance test was carried out to form a composite phase change material with temperature gradient laps. The influence of composite phase change materials on asphalt performance was tested. The test shows that the best composite ratio of phase change material A and phase change material B is 5:1, and the temperature regulation performance of composite phase change material is better than that of A and B alone. The ability of composite phase change material to inhibit cooling increases with the amount of admixture, and the best admixture ratio in the mixture is 5 ‰ of the total mass of the mixture.

Three-dimensional and high-resolution building energy simulation applied to phase change materials in a passive solar room

Phase change materials (PCMs) reduce energy consumption and improve indoor thermal comfort in buildings. Various numerical models have been developed to evaluate the thermal performance of the PCMs integrated into building enclosures. To remain computationally efficient, these models typically adopt a trade-off between the ability to investigate complex and realistic configurations and the prediction accuracy of the heat transfer associated with the phase change. This study developed a model to simulate a room with three-dimensional heat conduction in PCM-integrated walls and to analyze the surface heat balances with high resolution. The model was validated using experimental data of a passive solar test cell with a non-uniform and dynamic thermal environment. The model was then applied to investigate the PCMs integrated into the test cell during the summer. The PCM with a narrow phase change temperature range and a thickness of approximately 10mm was highly effective in reducing the indoor temperature fluctuations; the peak surface temperature was reduced by up to 6°C in the sun patch, and the operative temperature fluctuations decreased by up to 2.6°C. The PCM integration could be limited to the sun patch trajectory on the wall surfaces to optimize its utilization and limit the installation cost.