Effect Of Phase Change Material Research Articles

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.

Experimental investigation on the effect of phase change materials for thermal management improvement of the fast charging power module

This experimental research clarifies the advantageous effect of adding paraffin wax as the appropriate organic phase change material (PCM) to control the temperature rise of the fast charging power module (100 mm × 50 mm × 20 mm). The effects of PCM physical parameters (thermal conductivity, melting point temperature and filling thickness) on the thermal management performance of changing module are examined, and the PCM melting process is visualized to reveal the mechanism of PCM in improving the thermal management performance. Results show that the temperature is decreased by 46.4 °C with coupling the PCM, and a temperature reduction of 11.8 °C is found with increasing the air flow velocity. Increasing the PCM thermal conductivity from 0.2 W/(m∙K) to 5 W/(m∙K) in 1800 s can decrease the extreme temperature from 60.1 °C to 51.9 °C. The filling PCM thickness of 4.5 mm is more successful than other thicknesses in the thermal management performance. These research results will provide reliable technical solutions for improving the thermal management performance of charging piles and solving the effective thermal management of high-power quick charging piles.

Comparison of thermal conductivity of foamed geopolymers containing phase change materials

The aim of this work was to investigate the effect of Phase Change Materials on the insulation properties - thermal conductivity coefficient [λ], of fabricated foamed geopolymer panels. Phase Change Materials have been widely reported in the public literature, making them increasingly popular in recent times. PCMs have the ability to accumulate heat, which they can absorb or release due to thermal transformation, which contributes to energy efficiency. This paper presents the results of research on geopolymers based on fly ash with the addition of microencapsulated and macroencapsulated phase change materials (PCMs). Geopolymer composites were prepared by adding 0%, 5%, 10% and 15% PCM and the curing process was carried out at 60°C. Three different phase change materials with melting points of 28°C (MicroCapsPCM28 (Slovenia)) and 25°C and 42°C (PX25 and GR42 (Germany), respectively) were used. All the phase change materials used belong to the paraffin group. The obtained composite sheets were subjected to thermal conductivity tests in 3 temperature ranges (0-20°C; 20-40°C; 30-50°C). The paper also presents the density results of the foamed composites investigated, as well as the visual evaluation and the morphology of the porous structure using scanning electron microscopy. As a result of the study, it was found that foamed geopolymer composites without PCM addition have lambda coefficient values of 0.06 - 0.07 [W/m*K], while with the addition of phase change materials 0.07 - 0.085 [W/m*K]. The obtained test results give the potential to use these materials in construction as insulating materials. The use of these substances in building partitions results in the decrease of daily temperature amplitudes inside the building, as well as in the phase shift of the time of release of stored heat.

Experimental and Numerical Investigations on an Organic Phase Change Material Incorporated Cool Concrete Pavement

Background: Traditionally, cool pavements have been designed as reflective, evaporative, etc. Though the reflective pavements reduce the pavement surface temperature significantly, they increase glare, the thermal burden on pedestrian traffic, and the temperature of nearby buildings. In the case of evaporative pavements, the absence of water, reduced thermal inertia and solar reflection result in a higher pavement temperature. As a result, there has been a pressing need to investigate new low-side-effect cool pavement options. Objective: The study aims to analyze the effect of phase change material (PCM) incorporation on the thermal performance of concrete pavements and to develop a total enthalpy-based numerical heat transfer model for such cool pavements. Materials and Methods: A paraffin-based organic PCM with a melting point of 42 to 45 °C was used in this work, and expanded clay aggregate (ECA) was used as an encapsulation medium. Concrete slabs without and with the incorporation of PCM-impregnated ECAs were cast, and thermocouples were implanted in the concrete to monitor the pavement temperature continuously. A total enthalpy-based numerical heat transfer model was developed to predict the thermal performance of such cool concrete pavements. Results: The PCM incorporation reduced 2.24 °C in the annual average pavement surface temperature with a maximum reduction of 4.12 °C. Conclusion: PCM incorporation effectively reduces pavement surface temperature during the daytime and makes the pavements cooler. Increasing the encapsulating medium's porosity and the concrete slab's thermal conductivity enhances the cooling potential. However, the thermal characteristics of the encapsulating material may be neglected as their impact is less on the cooling potential.

Effect of Phase Change Material and Roof Shading on Cooling Load of Residential Unit in Basrah

In several countries, residential buildings are responsible for high energy consumption. The majority of energy is consumed on air conditioning to ensure maximum indoor comfort. In Iraq, the demand for electricity increases significantly, especially during the summer for cooling purposes. In this paper, two technologies are proposed for buildings to reduce the cooling load. These approaches included the use of phase-changing materials (PCM) in different locations in the walls and roof, in addition to roof shading by galvanized iron. The effects of these proposals were simulated in the latest software tool (designbuilder) and compared with the standard building model. The results were clear when PCM was installed on the outer surface of the wall and roof, which achieved the highest reduction in the cooling load of about 18 %. While the roof shading method using corrugated galvanized iron proved its effectiveness by decreasing the cooling load to 5 % compared to the standard case.

Synergistic effect of phase change materials and reduced graphene oxide in enhancing the thermoregulating properties of polymeric composites

Synergistic effect of phase change materials and reduced graphene oxide in enhancing the thermoregulating properties of polymeric composites

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.

Heat transfer enhancement of a bio-based PCM/metal foam composite heat sink

• The impacts of various PCM filling height ratios on the cooling performance of a PCM composite-based heat sink are examined experimentally. • The effects of three different pore sizes of copper foam on the heat transfer of PCM composites at varying heat loads are studied. • PCM/copper foam composite samples outperform pure PCM. • A PCM filling ratio of 1.0 results in little to no improvement in cooling performance. • The optimum cooling performance is provided by PCM/copper Foam-95PPI with a PCM filling ratio of 1.3. Effects of phase change materials (PCMs) filling height and copper foam pore densities on the cooling performance of a bio-PCM composite-based heat sink are investigated. In this respect, three filling height ratios of 1.0, 1.3, and 1.6 as well as three copper foam samples with pore densities of 35, 80, and 95 pores per inch (PPIs) are examined. Temperature profiles of the flat plate, the time required to reach specified temperatures, and the enhancement ratios at various temperatures and filling ratios are used to evaluate the thermal performance of the PCM composite-based heat sink. The investigation enables the determination of the optimal PCM filling height for maximum cooling performance of the heat sink. The results show that the optimal PCM filling height is 1.3 times the copper foam thickness and that a PCM/copper foam composite with 95 PPI pore density produces the best cooling performance with enhancement ratios of 1.54 and 1.44 under 10 and 15 W heat loads, respectively.

Performance improvement of adsorptive hydrogen storage on activated carbon: Effects of phase change material and inconstant mass flow rate

Due to the multiple advantages of activated carbon (e.g. high specific surface area, safety and low cost) toward hydrogen storage, the subject of heat management in H2-storage tanks has become a research focus in recent years. In this work, using a computational fluid dynamics (CFD) model (implemented in Fluent software), the performance of a hydrogen storage tank (packed with activated carbon) was analyzed in the presence of PCM/oil-based thermal recovery/release systems. The charging, dormancy, and discharging cycles of the storage tank were investigated with respect to the variation of the injected mass flow rate of hydrogen (from 2 × 10−4 to 8 × 10−4 kg/s). There was good agreement between our findings and those obtained from the experiment. It was observed that the adsorption capacity of the solid bed is proportionally enhanced with the rise in the mass flow rate of hydrogen. In addition, independently of the used hydrogen mass flow rate, it has been observed that the charging periods were ended at the same instant (i.e. t = 400 s). According to the enthalpy contours and liquid fraction of PCM (~18 and 30 % at 400 and 4000 s, respectively), it has been concluded that the thermal conductivities of the adopted PCM and that of solid bed (activated carbon) should be enhanced for better performance of the hydrogen stocking tank. Finally, from a viewpoint of storage performance and process cost, it is therefore possible to realize rapid charging/discharging of the activated carbon tank with adopting a PCM and oil-based thermal unit for heat management.

Effect of phase-change materials in the performance of a solar air heater

This work presents an experimental analysis of a double-channel solar air heater (SAH) with and without phase-change material (PCM) as thermal energy storage system (TES). Two identical prototypes were designed and constructed, and one of them was modified to house macro- encapsulated PCM in the absorber plate. Both collectors were evaluated in an experimental setup instrumented for hot air temperature and velocity, solar radiation, temperature probes in the glass cover, absorber plate, PCM storage system, and a weather station to record the environmental conditions. To evaluate the performance of the SAH under sudden variations of solar radiation, three different case studies were considered with varying conditions of weather: clear sky and high radiation, partially cloudy, and clear sky with a substantial drop in solar radiation at noon. The maximum outlet temperatures reached by the SAH with PCM were 82 °C, 62 °C, and 79.5 °C for the three cases, respectively. The outlet temperature of the SAH without PCM was consistently 10 °C lower compared to the collector with PCM. The PCM maintained the heating during day irradiation transients and extended it after dusk, without any decrease in the thermal efficiency. Further studies of modeling and design optimization appear very pertinent.

Optimized design of asphalt concrete pavement containing phase change materials based on rutting performance

This paper investigated the effects of phase change materials (PCMs) on temperature field and rutting performance of asphalt concrete (AC) pavement with a focus on PCM types, contents, and locations. To quantify their effects on rut depth accumulation, a pavement finite element (FE) model was constructed with measured material properties and designed structural configuration. The implemented traffic and environmental conditions were obtained from a FE model updating scheme and a heat transfer model with the consideration of traffic speed and the phase change process. Results showed that using polyethylene glycol of 4000 molar mass encapsulated by SiO2 as the PCM to replace 10% of the aggregate in the asphalt top sublayer yielded the best rutting performance; a 14% reduction in the rut depth that was accumulated within one month after pavement construction was predicted for a typical summer case in Texas. This study also revealed that incorporating PCMs into AC does not always lead to pavement rutting performance improvement. This is because (1) the lower thermal conductivity of the PCMs can offset the benefits achieved from the increased heat capacity during phase change, and (2) PCMs will not function if they are added in layers where pavement temperature is not high enough for PCMs to undergo the phase change. Therefore, developing PCMs with higher thermal conductivity together with a judicious selection of PCM types and locations will maximize the effectiveness of the pavement temperature and rutting control.

Effect of Phase-Change Materials on Laboratory-Made Insoles: Analysis of Environmental Conditions.

Thermal comfort is essential when wearing a postural-corrective garment. Discomfort of any kind may deter regular use and prolong user recovery time. The objective of this work is therefore to optimize a new compound that can alter the temperature of orthopedic insoles, thereby improving the thermal comfort for the user. Its novelty is a resin composite that contains a thermoregulatory Phase-Change Material (PCM). An experimental design was used to optimize the proportions of PCM, epoxy resin, and thickener in the composite and its effects. A Box–Behnken factor design was applied to each compound to establish the optimal proportions of all three substances. The dependent variables were the Shore A and D hardness tests and thermogravimetric heat-exchange measurements. As was foreseeable, the influence of the PCM on the thermal absorption levels of the compound was quantifiable and could be determined from the results of the factor design. Likewise, compound hardness was determined by resin type and resin-PCM interactions, so the quantity of PCM also had some influence on the mechanical properties of the composite. Both the durability and the flexibility of the final product complied with current standards for orthopedic insoles.

Effects of mechanical vibration on the heat transfer performance of shell-and-tube latent heat thermal storage units during charging process

Mechanical vibrations are unavoidable in thermal systems at certain times, but they do not only have a bad effect. This paper presents the first pioneering study of the effect of vibration on the heat transfer performance of a horizontal tubular heat exchanger. Through numerical simulation methods, by applying mechanical vibrations of different vibration frequencies and vibration amplitudes, the heat transfer enhancement effect of phase change material (PCM) under vibrational conditions are fully revealed. The results show that, under lower vibration frequencies (ω = 10 ∼ 20 Hz), which can significantly promote the mixing of melted PCM and melting heat transfer rate during charging processes. However, this heat transfer enhancement begins to weaken in the range of medium to high vibration frequencies. For all amplitudes, the heat transfer enhancement is markedly stronger than that of frequency, which is linked directly to the magnitude of the amplitude value. Furthermore, the effect on heat transfer enhancement has been discussed when there is an inclination of the vibration axis to the direction of gravity. When the inclination angle is varied from 0° to 90°, the contribution to heat transfer enhancement is greatest at θ = 30°, which is optimal inclination angle. This paper could fill the knowledge gap regarding the thermal performance of heat exchangers with different geometries under mechanical vibration and provide some guidance for future practical applications.

Effects of phase-change material on performance of cement mortar at varying temperatures

Recent thermal effect reports have shown a widespread increase in temperature associated with global warming. The need to preserve building interiors at a steady, comfortable temperature has become a major task for engineers. This has resulted in the development of phase-change materials (PCMs), which can be positioned in the interior of building components to absorb heat from the surroundings. The main aim of this study was to examine the physical, mechanical and thermal properties of cement mortar incorporating encapsulated PCMs at different temperature phases. The materials required for the PCMs and encapsulation were selected based on economy, availability and temperature tolerance. The results were compared with a control specimen and improved behaviour in thermal resistance was noted. The compressive strength was reduced with an increased percentage of PCM; the reduction in strength could be compensated with the addition of micro-silica. Temperature phases did not have much influence on the strength and durability properties. Based on thermal resistance and strength properties, 5% PCM incorporation showed the best performance. An analytical model was developed using Comsol Multiphysics software to assess the thermal comfort in a building made of PCM-incorporated mortar block walls in comparison with conventional brick walls.

Experimental evaluation of performance of a hybrid solar photovoltaic (PV/T) panel integrated with effective cooling solutions with water base nanofluids and phase change materials

ABSTRACT The overall performance of photovoltaic (PV) panels is prejudiced by the operating temperature of the solar cell owing to the absorbed solar radiation. In this experimental study, the in-house hybrid PV/thermal (PV/T) system is designed, fabricated, and parametrically studied for effective and practical applications of the solar panels. The water and water-based nanofluids are used for the active cooling of the PV/T system. The effect of phase change material (PCM) along with the active cooling is also studied, and results are comprehensively discussed. The in-house stable water-based Al2O3 and TiO2 nanofluids are engineered by the two-step method with two different nanoparticle concentrations of 0.05 and 0.1 vol.%. The thermal conductivity and stability of the nanofluids are experimentally measured and discussed to understand their effects on heat transfer from the PV panel. The thermal conductivity of nanofluids is increased with the concentration of nanoparticles in the base fluid. The maximum enhancement of around 30% is observed with Al2O3-water nanofluid at a concentration of 0.1 vol.%. The PV/T system is experimentally simulated in the indoor experimental setup with the solar simulator to provide the variable intensity of solar irradiance from 450 to 1050 W/m2. The maximum decrement in the panel’s temperature is found to be around 25% using both active and passive cooling simultaneously and the electrical efficiency is improved by approximately 10.3% at the 1050 W/m2. The electrical efficiency has found 13% more with Al2O3-water nanofluid of 0.1 vol% as compared to water cooling at 450 W/m2. The use of nanofluids also improved the system’s thermal efficiency compared to the water, and the maximum improvement of around 10% is achieved with the Al2O3-water nanofluid at 0.1 vol.% concentration. These results are significant for the design of the PV/T system from the application viewpoint.

Ecofriendly chitosan-derived carbon aerogels based eutectic hydrated salts for good solar thermal energy storage and corrosion mitigation effect

Emerging integrated latent heat storage and photothermal conversion have great potential to efficiently capture solar light and facilitate energy management. However, the energy conversion performances and application prospects are limited by poor solar absorption and corrosion effects of phase change materials (PCMs), especially hydrated salts. Here, eutectic hydrated salt is proposed for integration of practical solar thermal energy storage and corrosion mitigation effect. We design a facile method to formulate porous chitosan-based carbon aerogels with robust structure and orientated network by freeze-drying and carbonization processes. After impregnation with MgCl2·6H2O-NH4Al(SO4)2·12H2O eutectics, effective corrosion mitigation effect, enhanced thermal conductivity of 0.77 W/mK, and high energy storage density of up to 214.8 J/g are demonstrated simultaneously. The eutectic PCMs show photothermal conversion efficiency as high as 89.5 %, attributing to the synergistic effect of the molecular thermal vibrations of carbon nanomaterials and the local surface plasmon resonance (LSPR) effect of ZrC nanomaterials. This work creates a new avenue for high-efficiency solar energy storage and mitigating corrosion effect based on eutectic hydrated salts.

Effect of Phase Change Materials and Phase Change Temperature on Optimization of Design Parameters of Anaerobic Reactor Thermal Insulation Structure.

Direct-absorption anaerobic reactors can maintain the fermentation process of microorganisms by utilizing solar absorption and scattering media in the biogas reactor to improve the slurry temperature. Direct-absorption heating alone can save the corresponding electric energy and ensure the normal fermentation process of the biogas slurry in the reactor, but there is still the problem of temperature fluctuation. In order to improve the stability of the fermentation process, it is proposed to optimize the design of this kind of reactor by adding paraffin phase change material. This article mainly studies the influence of paraffin phase change material added on the top and side of the reactor in the fermentation process and gives the corresponding design parameters for different climatic conditions, which lays a theoretical reference for the design process of this kind of reactor.