Effect Of Phase Change Material Research Articles

Improved optical contrast of plasmonic phase change memory using a Fabry-Perot cavity

As a promising technology to realize multilevel, non-volatile data storage and information processing, optical phase change technologies have attracted extensive attention in recent years. However, existing phase-change photonic devices face significant challenges such as limited switching contrast and high switching energy. This study introduces an innovative approach to tackle these issues by leveraging Fabry-Perot (F-P) cavity resonance and plasmon resonance techniques to enhance the modulation effect of phase change materials (PCMs) on the light. To the best of our knowledge, a novel device structure is proposed, featuring an elliptic nano-antenna placed on an F-P cavity waveguide composed of symmetric Bragg grating. This design exploits the enhanced electric field to achieve low power consumption and high contrast. The device enables crucial functions, including read, write, and erase operations, under all light conditions. Through the synergistic utilization of plasma and F-P cavity effects, an ultra-high switching contrast of around 70.6% is achieved. By varying the pulse power or duration, the proportion between the crystalline and amorphous states of the PCMs is altered, consequently modifying its refractive index. With its wide range of applications in optical storage and computing, the device holds significant potential for advancing these fields.

Effect of phase change material in cross flow and jet impingement cooling techniques used in heat sink for electronics application

This article presents the results of numerical investigation on comparison between two different cooling techniques namely cross flow and jet impingement cooling techniques used in heat sinks for the electronic components. Pin fin heat sink with and without phase change material (PCM) are considered for the investigation. The main focus of this research is to reduce the peak operating temperature of electronic component and pressure drop and to increase the Nusselt number of the heat sinks. Computational fluid Dynamics (CFD) tool is used to model and investigate the heat transfer characteristics across the heat sink. It is found that the cross flow shows superior thermal characteristics compared to jet impingement method due to which the base temperatures of pin fins in cross flow is at an average temperature of 14.5° C lower than that of jet impingement. Furthermore, the use of PCM significantly reduces the operating temperature of the pin fins by an average temperature of 7.5 °C for cross flow and 6.1 °C for jet impingement flow techniques.

Tunable multispectral narrowband absorber and directional absorption enabled by layered quasi-periodic structure and phase-change materials

Based on the Optical Tamm States (OTS) effect of phase-change material (PCM) Ge-Sb-Te (GST), a tunable multispectral selective narrowband absorber is proposed. The application wavelength range is combined with the solar spectral distribution in this study. Compared with other absorbers with complex shapes, this planar device is easier to manufacture, making it possible for the photolithographic, large-scale, cost-effective manufacturing process. Through the phase change of GST, the multi-spectral narrowband absorption of the harmful gas SO2 (1.35 μm), NO2 (1.59 μm), NO (1.91 μm) and CO (2.1 μm) of the vehicle exhaust was finally realized. Meanwhile, it shows good directivity and polarization performance in the wavelength range of 1.7–2.0 μm, and finally high S-polarization absorptivity (>90 %) at 75–80° incident angle was achieved. The present work is of potential application value in the research areas of infrared detection, energy management, information encryption and so on.

Experimental Investigation of the Effect of Phase Change Material in Mitigation of Heat

The use of a latent heat storage system using phase change materials (PCMs) is an effective way of storing thermal energy and has the advantages of high-energy storage density and the isothermal nature of the storage process. PCMs have been widely used in latent heat thermal storage systems for heat pumps, solar engineering, and spacecraft thermal control applications. The uses of PCMs for heating and cooling applications for buildings have been investigated within the past decade. There are large numbers of PCMs that melt and solidify at a wide range of temperatures, making them attractive in a number of applications. This paper also summarizes the investigation and analysis of the available thermal energy storage systems incorporating PCMs for use in different applications.

Effectiveness of phase change materials and their properties on the performance of geothermal and foundation-based energy systems: A review

As buildings contribute notably to emissions of greenhouse gases, it is important to move towards building heating and cooling systems with good sustainability attributes and efficiencies, such as ground-source heat pumps (GSHPs). In this review, an integrated picture of the effect of utilizing phase change material (PCMs) having various physical properties on the performance of GSHPs and foundation-based geothermal systems is presented. Two major questions are addressed in this paper: how effective is a PCM for enhancing the performance of both conventional GSHP systems and foundation-based geothermal energy systems? The results show that PCMs can be effective at enhancing performance for conventional GSHP and foundation-based geothermal energy systems by, on average, 17% and 36%, respectively. However, the degree of PCM effectiveness depends on some parameters such as its physical characteristics (thermal conductivity, latent heat, phase change temperature) and design considerations (ground loop configuration, depth, etc.) among other factors. The results also show that, in general, the greater the PCM thermal conductivity, the higher the effectiveness of the PCM. Furthermore, by adding composites such as expanded graphite to the PCM, the thermal conductivity of a PCM increases more than 250% which can potentially improve the performance of geothermal systems. More research is warranted to maximize the system performance improvements by enhancing the PCM.

Thermal and acoustic performance of masonry walls with phase change materials: A comparison of scaled-down houses in tropical climates

This article examines experimentally and numerically the effectiveness of Phase Change Materials (PCMs) and a new type of hybrid sandwich insulated panel (SIP) at improving the thermal comfort of four case study houses built in Thailand. In Phase 1 of the experimental programme, three scaled-down house units were built with either a) traditional brick walls plastered with a cement-based mortar, b) brick walls plastered with a cement-based mortar mixed with a 15% of PCMs, or c) a new SIP panel termed UWall. The results are discussed in terms of temperature, relative humidity (RH), energy consumption and acoustic performance. It was found that the PCM plastering and UWall effectively reduced the temperatures in the unit between 1 °C and up to 5 °C compared to the counterpart unit with brick walls plastered with cement-based mortar. In Phase 2 of the tests, a 10 × 7 m full-scale house was built with one room built with brick walls plastered with the cement-based mortar-PCM mixture, and one room built with the new UWall. Temperature, RH and indoor air movement were recorded for 48 h. Results from a bioclimatic chart indicates that both temperature and RH in the rooms remained within the comfort zone at all times if air movement is considered. The three units and full-scale house were then modelled in ANSYS® software to carry out a heat transfer analysis. The modelling approach was successful at predicting the maximum temperatures in the tested case study houses (accuracy <7%). For the case study houses and climate conditions considered in this study, the mortar-PCM plastering proved a practical retrofitting solution to improve the thermal performance, RH, energy efficiency and acoustic resistance of existing brick walls. Similar solutions could be adopted to improve the thermal comfort in masonry walls of existing buildings. This article contributes towards developing more effective solutions to improve the thermal comfort in existing houses and buildings located in tropical regions, which in turn can help reduce energy consumption.

Experimental study on the effect of phase change material on thermal runaway characteristics of lithium-ion battery under different triggering methods

Although paraffin (PA) is a commonly used phase change material (PCM) for lithium-ion battery thermal management, its flammability may increase the risk of thermal runaway. This paper investigates the influence of PA on the thermal runaway, and the highly effective flame retardant hexa-phenoxy-cyclotriphosphazene (HPCP) was employed to suppress PA combustion and mitigate the thermal runaway hazard. Penetration and heating were used to induce thermal runaway. The battery surface temperature, the material temperature and the flame condition were recorded. The results show that penetration caused more violent reactions than heating, the battery temperature of penetration was 25 % higher than that of heating, while heating led to more harmful flame with a flame temperature over 1000 °C. PA delayed the onset of thermal runaway by 58.7 %, however, the higher temperature and longer burning time were a sign of increased danger. HPCP inhibited PA combustion, reducing the burn time by 35.7 %, while HPCP/PA delayed thermal runaway and controlled the battery flame, with a minimum of 43.5 % reduction in flame height. This study may provide a reference for the safe design of thermal management system for lithium-ion battery.

Productivity amelioration of stepped solar still using phase change material and evacuated tube collector

AbstractThis study investigates the individual and cumulative effects of phase change material (PCM) and evacuated tube collector (ETC) on the performance of a stepped solar still (SSS). Experiments have been performed on SSS, SSS loaded with PCM (SSS‐PCM), SSS coupled with ETC (SSS‐ETC), and SSS loaded with PCM and coupled with ETC (SSS‐PCM‐ETC). An innovative way of loading paraffin wax as PCM is introduced to utilize solar energy efficiently for the distillation process during off‐sunshine hours. ETC is used to provide pre‐heated RO wastewater to the distillation unit. The distillate output was observed maximum for SSS‐PCM‐ETC (4.97 kg/m2 day) which is 99% more than that of the SSS unit. The PCM and ETC individually with SSS unit increases the distillate output by 31% and 24%, respectively. The working time of the distillation unit was observed to be increased by 3 h by the use of PCM. The total heat transfer coefficient was evaluated at the maximum for SSS‐PCM‐ETC and was observed in the range of 16.94–167.04 W/m2 °C. The thermal energy efficiencies of SSS, SSS‐ETC, SSS‐PCM, and SSS‐PCM‐ETC were evaluated as 28.65%, 35.59%, 43.88%, and 44.04%, respectively. SSS‐PCM‐ETC is found to be the most economic with the best environmental conservation having maximum values of daily productive cost ($0.69) and carbon credits earned ($184.8).

Effect of phase change material (PCM) on thermal inertia of walls in lightweight buildings

The effect of a layer of phase change material on an increase in the thermal inertia properties of the outer wall in lightweight building has been numerically studied. Changes in thermal characteristics of the wall in the summer period at various locations of the PCM were analyzed. The regime of indoor air conditioning and the regime of daily in-phase change in the indoor and outdoor air temperatures are considered. It is shown that in the regime of indoor air conditioning, the use of a layer of 4-vol.% paraffin in a wall made of foamed polyurethane allowed reduction in the amplitude of heat flux fluctuations on the inner wall surface from 2 to 13 times, depending on PCM location. The greatest heat flux reduction was obtained when a PCM was mounted in the central area of the wall. It was calculated that the greatest effect of increasing the thermal inertia of the wall made of a light heat-insulating material in the regime of daily in-phase fluctuations in the indoor and outdoor air temperatures was observed when a PCM was located on the inner surface of the wall.

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.

The Effect of Phase Change Materials on the Physical and Mechanical Properties of Concrete Made with Recycled Aggregate

With the world’s population increasing, the issue of energy consumption has become increasingly prominent, particularly during the building operation phase, where substantial energy is required for heating and cooling. Presently, the energy necessary for buildings is sourced mainly from the combustion of fossil fuels, leading to not only energy scarcity but also severe environmental pollution and ecological damage. Furthermore, rapid urbanization has generated a lot of construction and demolition waste. To address these challenges, one promising approach is the incorporation of phase-change materials in recycled aggregate from construction and demolition waste to replace the raw materials of concrete. In this study, the phase-change material suitable for the thermal comfort requirements of buildings was selected and combined with recycled aggregate to replace the natural aggregate in concrete. All the materials used were characterized and three compositions were prepared. From the results, the workability of concrete increased with the phase-change materials added. Regarding water absorption performance, the incorporation of functionalized recycled aggregate presented a small water absorption performance. However, the mechanical performance decreased with the phase-change materials used. This work provides data for the application of phase-change materials in green concrete.

Multi-technique investigation on the surface interaction of diatomaceous earth with organic phase change material: Experimental and molecular dynamics aspects

To promote diatomaceous earth (DE)-based phase change composite as green energy building materials, this paper bridges the studies of experimental and molecular dynamics (MD) focusing on the absorption effect of phase change materials (PCMs). Octadecanoic acid (OA) was selected as PCMs and DE as supporting material for the fabrication of composite PCMs at different loading ratios; effect on thermal properties and porosity of the composite PCMs were further investigated by MD simulation. In consonance with ATR-FTIR and XRD analyses, the highest loading ratio (DEOA-4) was proven to absorb a high amount of PCMs, with excellent thermal stability and chemical compatibility. DEOA-4 exhibited higher latent heat storage capacity of 52.67 J/g, with a loading ratio and loading efficiency of 32.13 and 32.98 %. Besides, MD simulation showed that increasing the OA loading would decrease the fractional free volume of DEOA models, resulting in a limited mobility of PCMs molecules, as confirmed by self-diffusion coefficient at room and melting temperatures. Experimental and computational studies revealed that pore-filling process plays an imperative role during PCMs absorption. An adequate amount of loading ratio can potentially enhance the pore-filling process, maximize the efficiency of the performances, and promote the development of green energy in concrete structures.

Effect of Phase Change Materials on Mechanical Properties of Stabilized Loess Subgrade Subjected to Freeze–Thaw Cycle

Effect of Phase Change Materials on Mechanical Properties of Stabilized Loess Subgrade Subjected to Freeze–Thaw Cycle

THE EFFECT OF PHASE CHANGE MATERIALS ON ROOM TEMPERATURE FOR WINTER AND SUMMER

The efficient use of our existing energy resources is as important as finding new energy sources, since the demand for energy is increasing day by day. Heating and cooling loads in buildings constitute a large part of energy consumption. Therefore, it is very important to improve the energy performance of buildings. The utilization of phase change materials to increase the energy efficiency of buildings is one of the recent research topics. In this study, the effect of phase change materials on room temperature for winter and summer months was investigated numerically by defining real environmental conditions in the virtual environment. Phase change material with thermophysical properties suitable for Mediterranean climate conditions was selected for summer and winter. It can keep the room temperature at a slightly lower level during the daytime in summer and the room temperature higher in winter than in the insulated state case. As a result, phase change materials can be used as a natural air conditioner in the summer, as well as a natural heater at night in the winter. On the other hand, smart bricks can be produced that can absorb the heat transmitted from the inside to the outside by using different phase-change materials.

Effects of Phase Change Materials on the Freeze–Thaw Performance of Expansive Soil

Freeze–thaw cycles can deteriorate the expansive soil performance. Phase change materials (PCMs) absorb and store heavy latent heat from the environment, which can be utilized to mitigate freeze–thaw deteriorations in expansive soil. In this study, an environmentally friendly paraffin-based PCM was selected, which included two different forms: liquid (pPCM) and microcapsules (mPCM). The volume change, mechanical properties, thermal properties, and microstructure of the improved soil were studied. These results showed that PCMs can release considerable thermal energy during phase transitions, which improves the thermal stability of the soil. The pPCM enhanced the plasticity of soil and prevented brittle failure; mPCM reduced the damage to the soil microstructure caused by freeze–thaw cycles. Macroscopically, it weakened the swell–shrink behavior and limited the degradation of the resilient modulus, unconfined compressive strength, and failure strain of expansive soil. The optimal PCM content was determined based on the mechanical and thermal properties of the improved soil. This study provides a new idea for the engineering treatment of expansive soil in cold regions.

Experimental investigation of the effect of phase change materials on the behavior of battery at high-rate discharge in electric tools

Phase change materials (PCMs) are currently popular in battery thermal management for electric tools discharged at high-rate due to their small size and ecologically harmless. However, there is currently a little discussion on batteries with high discharge rates (≥10C) under PCMs thermal management. An experimental study was performed in this work to investigate the effects of the thickness of PCMs (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm), depth of discharge (DOD) levels (70% and 80%), and ambient temperature (25 °C and 40 °C) on the behavior of the battery at high-rate discharge. The results indicate that wrapping 2 mm PCMs can reduce the surface temperature of the battery and increase the discharge time by 64 s at 15C discharge. In addition, the aging of battery wrapped with PCMs is classified into three stages under the DOD limitation, which has a strong correlation with temperature. Furthermore, using PCMs under appropriate operating conditions can effectively prevent the battery temperature from overheating and improve the discharge capacity. At 25 °C and 10C discharge rate, the cycle life and total capacity are improved by 14% and 24%, respectively.

Prevention and suppression effects of phase change material on thermal runaway in batteries

With the rapid improvement in the electric vehicle industry, lithium-ion batteries are being used in increasing numbers. However, lithium-ion batteries are prone to thermal runaway under various factors, leading to fires and explosions that seriously affect the security of electric vehicles. Therefore, a method for effectively preventing and suppressing thermal runaway in batteries is an important problem that needs to be solved. The phase change material can absorb a large quantity of heat during the solid‒liquid transition process, exhibiting strong potential for thermal runaway protection in lithium-ion batteries. In this research, a lithium-ion battery module is proposed with cylindrical cells and paraffin phase change material. The prevention and suppression effects of the phase change material on thermal runaway in the cells are analyzed by a numerical method. The phase change material can effectively reduce the maximum temperature of the trigger cell and stop the propagation of thermal runaway in the module. By varying the thermal conductivity, latent heat, melting temperature and thickness of the phase change material, their influences on the heat generation and temperature of the trigger cell during thermal runaway are analyzed. Design recommendations for phase change materials to protect lithium-ion batteries from thermal runaway are provided based on the results.

Thermal performance evaluation of new energy vehicle pre-charge resistors based on phase change material cooling

Thermal management of new energy vehicles is a crucial factor restricting their development. For the possible short-circuit problem of capacitors in the motor controller circuit of new energy vehicles, a scheme of using phase change materials to cool the pre-charge resistors of new energy vehicles is proposed. The effects of phase change materials’ parameters such as length, diameter, and eccentricity on the temperature rising and heat storage capacity of pre-charge resistors are evaluated. The results indicate that phase change materials can improve the thermal performance of the pre-charge resistor. The pre-charge resistor’s thermal properties can be optimized by increasing the phase change materials’ diameter, length, and eccentricity. When the phase change materials’ diameter is 6 mm and the length is 38 mm, the resistance core/ phase change material has the strongest heat storage capacity, which can be increased by 152.29% compared with that without phase change material. The capacity of the resistance core/ phase change material to store heat can be increased by 5.72% when the eccentricity is 1 mm as opposed to 0 mm. The study’s conclusions can be used as a theoretical direction when designing pre-charge resistors.

Effect of Phase Change Materials on the Optical Path of LEDs for Opto-Thermal Enhancement

A novel concept based on the encapsulation of transparent phase change materials (PCMs) into the optical packaging structure of light-emitting diodes (LEDs) is presented in this article. The concept was initiated by challenges of thermal management of photoluminescent particles in high-power optical systems. LEDs, white LEDs (WLEDs), and porous/network-based photoluminescent matrices can achieve improved thermal networks by embedding PCMs. In this article, paraffin is selected as a suitable PCM encapsulant, and aside from thermal perspectives, an unexpected optical benefit with melted paraffin after surface wetting of the chip was observed. Immersing an LED chip in a melted paraffin pool showed up to an 8% increase in light extraction efficiency and a 1.5% increase in power conversion efficiency (PCE). An accurate dynamic opto-electro-thermal monitoring of studied devices was used to support the proof of concept. This viable method can be integrated into current industrial packaging processes.

Thermal Performance Optimization Simulation Study of a Passive Solar House with a Light Steel Structure and Phase Change Walls

Phase change materials are used in passive solar house construction with light steel structure walls, which can overcome the problems of weak heat storage capacity and poor utilization of solar heat and effectively solve the thermal defects of light steel structure walls. Based on this, on the basis of preliminary experimental research, this study further carried out theoretical analysis and simulation research on the thermal performance of a light steel structure passive solar house (Trombe form) with PCM walls. Through the heat balance analysis of heat transfer in the heat collecting partition wall, the theoretical calculation formula of the phase change temperature of the PCM was obtained, and it verified theoretically that the phase change temperature value should be 1–3 °C higher than the target indoor air temperature. The evaluation index “accumulated daily indoor temperature offset value” was proposed for evaluating the effect of phase change materials on the indoor temperature of the passive solar house, and “EnergyPlus” software was used to study the influence of the phase change temperature, the amount of material, and the thickness of the insulation layer on the indoor air temperature in a natural day. The results showed that there was a coupling relationship among the performance and between of the thickness of the PCM layer and the phase change temperature. Under typical diurnal climate conditions in the northern Tibetan Plateau of China, the optimal combination of the phase change temperature and the layer thickness was 17 °C and 15 mm, respectively. Especially at a certain temperature, excessive increases in the thickness of the phase transition layer could not improve the indoor thermal environment. For this transition temperature, there exists an optimal transition layer thickness. For a Trombe solar house, the thickness of the insulation layer has an independent impact on indoor temperature compared to other factors, which has an economic value, such as 50 mm in this case. In general, this paper studied the relationship between several important parameters of the phase change wall of a solar house by using numerical simulation methods and quantitatively calculated the optimal parameters under typical meteorological conditions, thus providing a feasible simulation design method for similar engineering applications.