Journal articles: 'Thermal field with phase change'

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Peng, Guangjian, Guijing Dou, Yahao Hu, Yiheng Sun, and Zhitong Chen. "Phase Change Material (PCM) Microcapsules for Thermal Energy Storage." Advances in Polymer Technology 2020 (January 12, 2020): 1–20. http://dx.doi.org/10.1155/2020/9490873.

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Phase change materials (PCMs) are gaining increasing attention and becoming popular in the thermal energy storage field. Microcapsules enhance thermal and mechanical performance of PCMs used in thermal energy storage by increasing the heat transfer area and preventing the leakage of melting materials. Nowadays, a large number of studies about PCM microcapsules have been published to elaborate their benefits in energy systems. In this paper, a comprehensive review has been carried out on PCM microcapsules for thermal energy storage. Five aspects have been discussed in this review: classification of PCMs, encapsulation shell materials, microencapsulation techniques, PCM microcapsules’ characterizations, and thermal applications. This review aims to help the researchers from various fields better understand PCM microcapsules and provide critical guidance for utilizing this technology for future thermal energy storage.

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Ghanekar, Alok, Yanpei Tian, Matthew Ricci, Sinong Zhang, Otto Gregory, and Yi Zheng. "Near-field thermal rectification devices using phase change periodic nanostructure." Optics Express 26, no. 2 (January 18, 2018): A209. http://dx.doi.org/10.1364/oe.26.00a209.

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Chen, Jie, Feng Jiao Liu, and Yi Fei Zheng. "Review on Phase Change Material Slurries." Advanced Materials Research 860-863 (December 2013): 946–51. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.946.

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Phase change materials (PCM) have recently received considerable attention in the field of thermal energy storage, due to their intrinsic properties. Phase change material slurry is a novel medium of heat storage and transfer, its apparent specific heat and heat transfer capacity is better than water.PCM slurries are being investigated for active thermal energy storage or as alternatives to conventional single phase fluids because they are pumpable and have advanced heat transport performance with phase change. This review mainly presents the information on PCM emulsions and microencapsulated PCM slurries (mPCM slurries).

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Ghanekar, Alok, Jun Ji, and Yi Zheng. "High-rectification near-field thermal diode using phase change periodic nanostructure." Applied Physics Letters 109, no. 12 (September 19, 2016): 123106. http://dx.doi.org/10.1063/1.4963317.

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Goodrich, L. E. "Field measurements of soil thermal conductivity." Canadian Geotechnical Journal 23, no. 1 (February 1, 1986): 51–59. http://dx.doi.org/10.1139/t86-006.

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Data representing the seasonal variation of thermal conductivity of the ground at depths within the seasonally active freezing/thawing zone are presented for a number of different soil conditions at four sites across Canada. An inexpensive probe apparatus suitable for routine field measurements is described.In all the cases examined, significant seasonal variations were confined to the first few decimetres. In addition to distinct seasonal differences associated with phase change, quite large changes occurred during the period when the soil was thawed in those cases where seasonal drying was possible. Below the seasonally active zone, thawed soil conductivities did not differ greatly among the three nonpermafrost sites in spite of soil composition ranging from marine clay to sandy silt. The data suggest that, even within a given soil layer, quite significant differences in thermal conductivity may be encountered in engineering structures such as embankments, presumably because of differences in drainage conditions. Key words: thermal conductivity, field measurements, phase relationships, drying, permafrost, clay, silt, peat.

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Hu, Tao, Yan Li, Duo Su, and Hai Xia Lv. "Thermal Modeling Solid-Liquid Phase Change Materials (PCMs)." Advanced Materials Research 746 (August 2013): 161–66. http://dx.doi.org/10.4028/www.scientific.net/amr.746.161.

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Three thermal modeling methods for phase change materials (PCMs): enthalpy-based method, effective heat capacity method and apparent heat capacity method, are presented in details. Their characteristics and application limitations are compared and discussed. We found that enthalpy-based method and effective heat capacity method are both approximation treatments, and can be well used in steady state problems, while apparent heat capacity method tracks the moving phase change boundary in PCMs, and it is the most accurate and applicable method of the three for dealing with transient processes. This work might provide useful information for the study of using PCMs in temperature control field, especially in aircraft environmental temperature control and thermal management.

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Guo, Z., Jia Wei Mi, and Patrick S. Grant. "Phase Field Modelling of Dendrite Fragmentation during Thermal Shock." Materials Science Forum 654-656 (June 2010): 1524–27. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1524.

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The dendrite grain growth of a succinonitrile based transparent alloy, their fragmentation under an intense thermal shock and the subsequnet morphology evolution during solidification have been simulated using a two-dimensional binary alloy phase field model coupled with heat and solute transfer. The effect of a sudden, rapid change in the thermal environment (thermal shock) was implemented in the model and the resulting effect on the incipient dendritic grain morphology was studied. Thermal shock effectively promoted the fragmentation of the dendritic grains, providing a significant grain multiplication effect to refine the final solidification microstructure.

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Kanimozhi, B., Amit Arnav, Eluri Vamsi Krishna, and R. Thamarai Kannan. "Review on Phase Change Materials in Thermal Energy Storage System." Applied Mechanics and Materials 766-767 (June 2015): 474–79. http://dx.doi.org/10.4028/www.scientific.net/amm.766-767.474.

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Phase Change Materials (PCM) plays an important role in energy conservation, which is very attractive because of its high storage density with small temperature change. In this paper an attempt made to review number of paper based on Phase Change Materials (PCM) in various field of thermal energy storage systems and its applications. The Phase Change Material is the latent heat storage material. As the source temperature raises the chemical bonds within the PCM breaks and the material changes its phase from one phase to another phase. The material begins to melt when the phase change temperature is reached. The temperature then stays constant until the melting process is finished. Thermal Energy Storage deals with the storing of energy by cooling, heating, melting, solidifying or vaporizing a material, the energy becoming available as heat when the process is reversed. Hence it is important to study about phase change materials in thermal energy storage system.Keywords: Phase change materials, Thermal energy storage system, Encapsulation, solar system, Heating and cooling of building

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Klemenčič, Eva, and Mitja Slavinec. "Liquid Crystals as Phase Change Materials for Thermal Stabilization." Advances in Condensed Matter Physics 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/1878232.

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Thermal stabilization exploiting phase change materials (PCMs) is studied theoretically and numerically. Using the heat source approach in numerical simulations, we focus on phase change temperature as a key factor in improving thermal stabilization. Our focus is to analyze possible mechanisms to tune the phase change temperature. We use thermotropic liquid crystals (LCs) as PCMs in a demonstrative system. Using the Landau-de Gennes mesoscopic approach, we show that an external electric field or appropriate nanoparticles (NPs) dispersed in LCs can be exploited to manipulate the phase change temperature.

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Vance, Ian W., and Paul C. Millett. "Phase-field simulations of pore migration and morphology change in thermal gradients." Journal of Nuclear Materials 490 (July 2017): 299–304. http://dx.doi.org/10.1016/j.jnucmat.2017.04.027.

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Yang, Shu. "Phase Change Materials Applied in Thermal Design." Advanced Materials Research 750-752 (August 2013): 1211–14. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.1211.

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Phase change material has been widely used in the fields of solar energy, aerospace, aviation, and buildings. In this paper, paraffin is applied in the thermal design of electronic equipment, in order to maintain a constant working circumstance. Finite-element analysis is implemented to analyze the feasibility of this thermal design.

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Qiu, Lin, Zhi Tan, and Min Yan. "Thermal Characteristics of PCMs - TH29 in Building Energy Storage." Advanced Materials Research 399-401 (November 2011): 1218–21. http://dx.doi.org/10.4028/www.scientific.net/amr.399-401.1218.

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Phase change materials (PCMs) using in the building energy storage field can satisfy people’s requirement of thermal comfort and attain function of energy saving and adjustment. This article experimental studies thermal Characteristics of a hydrated salt PCMs (TH29) ,which involves phase change process and was used in building energy storage, tests the different solid/liquid ratio of the phase change material, the whole time of phase change, and the delayed effect at different locations in phase change process, phase-changing cycles and thermal stability and TH29 temperature variety at heating and cooling modes and the delay phenomena on different location. The experimental results show that a good thermal stability of TH29 after long term phase-changing cycles can be attained under this test condition.

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N, Pradeep, and Somesh Subramanian S. "Performance Improvement of a Household Refrigerator using Phase Change Material." Journal of Manufacturing Engineering 16, no. 1 (March 1, 2021): 032–41. http://dx.doi.org/10.37255/jme.v16i1pp032-041.

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Thermal energy storage through phase change material has been used for wide applications in the field of air conditioning and refrigeration. The specific use of this thermal storage has been for energy storage during low demand and release of this energy during peak loads with potential to provide energy savings due to this. The principle of latent heat storage using phase change materials (PCMs) can be incorporated into a thermal storage system suitable for using deep freezers. The evaporator is covered with another box which has storage capacity or passage through phase change material. The results revealed that the performance is increased from 3.2 to 3.5 by using PCM.

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Li, Zhi Yong, Zheng Yong Wang, Qu Fan, and Zhan Wu. "The Interval Analysis for Uncertainty Heat Transfer Process of Phase Change Thermal Storage Based on Perturbation Method." Advanced Materials Research 838-841 (November 2013): 1939–43. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.1939.

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Due to phase change materials (PCMs) composition, machining error, measuring error and other factors, the PCMs thermal physical properties, geometric properties, etc are usually uncertain. As a result, phase change heat transfer process is an uncertainty heat transfer process. But at present, heat transfer characteristics research on phase change thermal storage are all based on certainty heat transfer models (Taken uncertainty factors as certainty factors). In this paper, it is considered factors uncertainty influencing phase change thermal storage heat transfer process. By looked on the variation scope of influence factors as "interval number", based on interval mathematics, perturbation method and finite difference method, "interval number" heat transfer model of phase change thermal storage is established. In this model, the uncertainty variables are decomposed into the sum of the nominal value and the deviation value. PCM uncertainty temperature field can be determined by calculated nominal value and the deviation value of PCM temperature field separately. Comparison between simulation results of the model and experimental data implies that it is necessary to consider influencing factors uncertainty in phase change thermal storage heat transfer analysis.

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Wei, P. S., T. H. Wu, and S. S. Hsieh. "Phase Change Effects on Transport Processes in Resistance Spot Welding." Journal of Mechanics 27, no. 1 (March 2011): 19–26. http://dx.doi.org/10.1017/jmech.2011.3.

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ABSTRACTThe effects of distinct properties during phase change on mass, momentum, energy, species, and magnetic field intensity transport in workpieces and electrodes in the course of heating, melting, cooling and freezing periods in AC (alternative current) resistance spot welding are realistically and extensively investigated. Resistance spot welding has been widely used in joining thin workpieces due to its light weight and easy manufacturing. This study accounts for electromagnetic force, heat generations at the electrode-workpiece interface and faying surface between workpieces, and dynamic electrical resistance taking the sum of temperature-dependent bulk resistance of the workpieces and contact resistances at the faying surface and electrode-workpiece interface. The contact resistance is a function of hardness, temperature, electrode force, and surface condition. Instead of dealing with specific materials, this work is a general dimensionless investigation of resistance spot welding of materials with different specific heat and thermal conductivity ratios subject to realistic working parameters. The computed results show that nugget formation is delayed and heat transfer is reduced by increasing solid-to-liquid thermal conductivity and liquid-to-solid specific heat ratio. The corresponding thermal fields and flow patterns are also presented.

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TAKADA, NAOKI, and AKIO TOMIYAMA. "NUMERICAL SIMULATION OF ISOTHERMAL AND THERMAL TWO-PHASE FLOWS USING PHASE-FIELD MODELING." International Journal of Modern Physics C 18, no. 04 (April 2007): 536–45. http://dx.doi.org/10.1142/s0129183107010772.

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For interface-tracking simulation of two-phase flows in various micro-fluidics devices, we examined the applicability of two versions of computational fluid dynamics method, NS-PFM, combining Navier-Stokes equations with phase-field modeling for interface based on the van der Waals-Cahn-Hilliard free-energy theory. Through the numerical simulations, the following major findings were obtained: (1) The first version of NS-PFM gives good predictions of interfacial shapes and motions in an incompressible, isothermal two-phase fluid with high density ratio on solid surface with heterogeneous wettability. (2) The second version successfully captures liquid-vapor motions with heat and mass transfer across interfaces in phase change of a non-ideal fluid around the critical point.

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Boldrini, Jos� Luiz, and Gabriela Planas. "Weak solutions of a phase-field model for phase change of an alloy with thermal properties." Mathematical Methods in the Applied Sciences 25, no. 14 (2002): 1177–93. http://dx.doi.org/10.1002/mma.334.

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Ho, Jia Jun, Jek Chong Lee, Tow Chong Chong, and Luping Shi. "Three-Dimensional Thermal Modelling and Analysis of Near-Field Phase Change Optical Disks." Japanese Journal of Applied Physics 39, Part 1, No. 2B (February 28, 2000): 952–56. http://dx.doi.org/10.1143/jjap.39.952.

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Qiu, Lin, Run Ping Niu, and Zhi Tan. "Experimental Research of PCMs - TH29 Using on Building Energy Storage." Advanced Materials Research 569 (September 2012): 202–6. http://dx.doi.org/10.4028/www.scientific.net/amr.569.202.

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This article experimental studies the thermal Characteristics of a hydrated salt TH29 Phase change materials (PCMs),which involves phase change process and was used in building energy storage field, tests the different solid/liquid ratio of the phase change material, the whole time of phase change, and the delayed effect at different locations in phase change process, phase-changing cycles and thermal stability and TH29 temperature variety at heating and cooling modes and the delay phenomena on different location. The experimental results show that a good thermal stability of TH29 after long term phase-changing cycles can be attained under this test condition. It can satisfy people’s requirement of thermal comfort and attain function of energy saving and adjustment.

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Shili, Haythem, Kamel Fahem, Souad Harmand, and Jabrallah Ben. "The effect of water’s presence around the Phase Change Material." Thermal Science 24, no. 6 Part B (2020): 4049–59. http://dx.doi.org/10.2298/tsci180922301s.

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As part of the research in the field of thermal control of electronic components, a phase change material is confined in a liquid and is heated vertically on one side by a hot plate. The presence of the liquid around the phase change material prevents the formation of air bubbles produced in case of direct contact between the hotplate and the phase change material (extends the lifetime of the phase change material by reducing overheating zones). It improves heat transfer by increasing the thermal conductivity around the phase change material (raising the thermal exchange surface) and by accelerating the convective transfer. This work examines experimentally and numerically the effect of the water on the phase change material and on the heating plate. The water is used around the phase change material and a comparative study of the comportment of some important parameters like the melt front form, melting time, flow direction, temperature, and operating time is realized. It is found that the presences of the liquid around the phase change material seems to be more interesting for a thermal protection role than the standard case of the phase change material directly heated by the hotplate.

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Lecoq, Nicolas, Jacques Lacaze, Frédéric Danoix, and Renaud Patte. "Phase-Field Modelling of Spinodal Decomposition during Ageing and Heating." Solid State Phenomena 172-174 (June 2011): 1072–77. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.1072.

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Despite the tremendous success of phase-field (PF) modelling in predicting many of the experimentally observed microstructures in solids, additional progress is required in order to apply it to predict microstructure evolution in real alloy systems. One way to achieve this is to couple thermodynamic and kinetic databases with PF model. In this work, we present phase-field simulations of spinodal decomposition in Fe-Cr alloy during thermal ageing and anisothermal heating. In the PF method, the local free energy is directly constructed using the CALPHAD method. During isothermal ageing, the morphology of decomposed phases consisted in an interconnected irregular shape for short ageing times, and a further ageing caused the change to a droplet like shape of the decomposed Cr-rich phase. The influence of heating rate on phase transformations is then simulated and compared with experimental results obtained by differential thermal analysis, carried out with heating rates in the range 0.5 °C.min-1to 15 °C.min-1. The simulation results show that heating rate strongly influences the microstructure morphology.

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Yang, Yan Yang, Hao Wang, Guo Lin Song, and Guo Yi Tang. "Dual-Functional Phase Change Nanocapsules Based on n-Octadecane Core and Polypyrrole Shell." Key Engineering Materials 697 (July 2016): 781–84. http://dx.doi.org/10.4028/www.scientific.net/kem.697.781.

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Phase change method is one of the efficient approach in resolving energy problem for solar energy storage. However, phase change materials seriously affect the heat storage system with low heat releasing and absorbing rate for poor thermal conductivity performance, which result in an inefficient thermal energy storage technology and uncertain economic perspective. In this paper, we prepared dual-functional phase change nanocapsules based on n-octadecane core and polypyrrole shell. Polypyrrole was employed to enhance the electric conductivity and thermal conductivity. The nanocapsules was characterized using Fourier transformed infrared spectrophotometer (FTIR), field emission scanning electron microscope (FESEM), differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA) and infrared thermal imaging. The results shows a good thermal behavior and high latent heat of 81.99J/g. The dual-fuctional phase change nanocapsules can be expected with a prospect of future profits in energy storage technology.

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Zhao, Y., C. Y. Zhao, Z. G. Xu, and H. J. Xu. "Modeling metal foam enhanced phase change heat transfer in thermal energy storage by using phase field method." International Journal of Heat and Mass Transfer 99 (August 2016): 170–81. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.03.076.

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Jovanovic, Dalibor, Radovan Karkalic, Ljubisa Tomic, Zlate Velickovic, and Sonja Radakovic. "Efficacy of a novel phase change material for microclimate body cooling." Thermal Science 18, no. 2 (2014): 657–65. http://dx.doi.org/10.2298/tsci130216129j.

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The present study was conducted in order to evaluate the efficiency of personal body microclimate cooling systems based on a phase change materials (PCM) and its effects on physiological strain in soldiers during exertional heat stress in hot environment. The results are obtained in the experiment conducted in the climatic chamber in the Institute of Hygiene, Military Medical Academy in Belgrade. Ten male soldiers were voluntarily subjected to exertional heat stress tests (EHST) consisted of walking on treadmill (5.5 km/h) in hot conditions (40?C) in climatic chamber. The subjects performed first test while wearing a field camouflage uniform without any cooling system ("CONTROL" group) and in second test they used additional microclimate cooling system with paraffin wax consist of n-hexadecane (C16H34), in a form of cooling packs ("COOL" group). As indicators of thermal strain, mean skin (Tsk) and tympanic (Tty) temperature were determined. Simultaneously, thermal effects of PCM were measured by thermal imaging camera. The exercise in hot conditions induced a physiological response to heat stress, manifested through increased body core and skin temperatures. The results confirmed that the cooling vest worn over the field uniform was able to attenuate the physiological strain during exercise, compared to the identical exposure in the ''control'' group. The results of thermal imaging also indicate that heat generated inside the body is the main factor that will affect the phase change material melting time.

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Jiang, Wei Jiang. "The Study of Heat-Engines Based on Refrigerant Phase-Change Circulation." Applied Mechanics and Materials 66-68 (July 2011): 649–53. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.649.

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This paper firstly introduces the principles of Stirling heat engines based on refrigerant phase-change circulation. This heat engines use two external heat reservoire. When the refrigerant in an engine cylinder absorbs heat from high-temperature heat sources, refrigerant is transformed from liquid to gas and the volume of the refrigerant expands to drive the piston apply work. When the refrigerant releases heat to low-temperature sources, the volume of the refrigerant shrinks. Therefore, phase change thermal engine technology using solar energy, industrial waste heat and heat produced by combustion of any fuel to work, no gas emissions, high thermal efficiency and environmental advantages. Thermal phase transition and thus the engine technology will be in the field of energy and power of a cutting-edge technology, great development potential and prospects.

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Gariboldi, Elisabetta, Luigi P. M. Colombo, Davide Fagiani, and Ziwei Li. "Methods to Characterize Effective Thermal Conductivity, Diffusivity and Thermal Response in Different Classes of Composite Phase Change Materials." Materials 12, no. 16 (August 10, 2019): 2552. http://dx.doi.org/10.3390/ma12162552.

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The phase change materials (PCMs) used in devices for thermal energy storage (TES) and management are often characterized by low thermal conductivity, a limit for their applicability. Composite PCMs (C-PCM), which combine active phase (proper PCM) with a passive phase with high conductivity and melting temperature have thus been proposed. The paper deals with the effect of length-scale on thermal characterization methods of C-PCM. The first part of the work includes a review of techniques proposed in the scientific literature. Up to now, special focus has been given to effective thermal conductivity and diffusivity at room or low temperature, at which both phases are solid. Conventional equipment has been used, neglecting length-scale effect in cases of coarse porous structures. An experimental set-up developed to characterize the thermal response of course porous C-PCMs also during active phase transition at high temperature is then presented. The setup, including high temperature-heat flux sensors and thermocouples to be located within samples, has been applied to evaluate the thermal response of some of the above C-PCMs. Experimental test results match Finite Elements (FE) simulations well, once a proper lattice model has been selected for the porous passive phase. FE simulations can then be used to estimate temperature difference between active and passive phase that prevents considering the C-PCM as a homogeneous material, to describe it by effective thermo-physical properties. In the engineering field, under these conditions, the design steps for TES systems design cannot be simplified by considering C-PCMs as homogeneous materials in FE codes.

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WEINFURTER, HARALD, and GERALD BADUREK. "THE NON-CYCLIC BERRY PHASE." Modern Physics Letters A 05, no. 28 (November 10, 1990): 2291–96. http://dx.doi.org/10.1142/s0217732390002626.

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By analyzing the change of the polarization of a thermal neutron beam on its passage through a magnetic field rotating at various speeds, it is demonstrated that geometric phase shifts of quantum states first introduced by Berry can be observed also for non-cyclic incomplete evolutions in parameter space.

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Kozlovskiy, Artem, Jumat Kargin, Malik Kokarev, and Daut Mukhambetov. "Study of the iron nanoparticles phase transformation during thermal annealing." Chemical Bulletin of Kazakh National University, no. 1 (March 31, 2017): 16–25. http://dx.doi.org/10.15328/cb796.

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Change in structural properties and phase composition of nanoparticles based on iron oxide was researched in the paper. As a result of conducted studies it was found that during heat treatment oxide phases of (γ-Fe2O3) and α-Fe2O3 maghemite were formed in oxygen atmosphere. Researches of powder array magnetization were showed that the hysteresis loop movement had the form characteristic for ferromagnetic materials. Additionally, loops obtained at different directions of the magnetic field have different characters, which indicate the magnetic anisotropy presence in the samples.

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Tahan Latibari, Sara, Mohammad Mehrali, Mehdi Mehrali, Teuku Meurah Indra Mahlia, and Hendrik Simon Cornelis Metselaar. "Facile Preparation of Carbon Microcapsules Containing Phase-Change Material with Enhanced Thermal Properties." Scientific World Journal 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/379582.

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This study describes the hydrothermal synthesis of a novel carbon/palmitic acid (PA) microencapsulated phase change material (MEPCM). The field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) images confirm that spherical capsules of uniform size were formed with a mean diameter of 6.42 μm. The melting and freezing temperature were found to be slightly lower than those of pure PA with little undercooling. The composite retained 75% of the latent heat of pure PA. Thermal stability of the MEPCM was found to be better than that of pure PA. The thermal conductivity of MEPCM was increased by as much as 41% at 30°C. Due to its good thermal properties and chemical and mechanical stability, the carbon/PA MEPCM displays a good potential for thermal energy storage systems.

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Chunxue, Gao, Wu Songlin, Lang Junqian, and Liu Qiuxin. "Simulation and experimental study of phase change cooling and heating wall radiation air conditioning system." E3S Web of Conferences 143 (2020): 02044. http://dx.doi.org/10.1051/e3sconf/202014302044.

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This paper presents a case study of phase change cooling and heating wall radiant (PC-CHWR) air conditioning system application in an energy-saving renovation project in a laboratory in Wuhan, Hubei province in China. To test the thermal performance of the system, the PHOENICS software was utilized to simulate and analyse the indoor thermal environment in the laboratory under both winter and summer operating conditions. In addition, field experiments were also conducted under winter operation condition. By comparing the results between numerical simulation and field experiment, it is found that thermal performance of the PC-CHWR air conditioning system evaluated by these two evaluation methods are quite match. Moreover, the results also show that the PC-CHWR system can meet the cooling and heating load of the building within the acceptable range.

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Hou, Hua, and Yu Hong Zhao. "Simulation for the Fluctuation Effect on the Dendrites Growth with Phase Field Method." Materials Science Forum 704-705 (December 2011): 1338–48. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.1338.

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The dendrite growth process was simulated with the Phase Field Model coupled with the fluctuation. The effect of fluctuation intensity on the dendrite morphology and the thermal fluctuation together with the phase field fluctuation on the forming of side branches were investigated. Result shows that with the decrease of thermal fluctuation amplitude, the furcation of dendrites tip also decreased, transverse dendrites become stronger and lengthways dendrites becomes degenerate, Doublon structure disappeared, finally a quite symmetrical dendrites structure formed. Thermal fluctuation can result in the unsteadiness of dendrites side branches, it is also the main reason of forming side branches, yet phase field fluctuation has little contribution to the side branches, it is usually ignored in the calculation; when the value ofFuis appropriate, the thermal noise can lead the side branches, but cannot change the steady behavior of the dendrites’ tip.

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Wu, Xiangxiang. "Review on phase change materials and application in building energy saving." E3S Web of Conferences 236 (2021): 05006. http://dx.doi.org/10.1051/e3sconf/202123605006.

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Phase change materials (PCMs) can be used for thermal energy storage and temperature regulation during phase change, and have broad application prospects in energy-efficient use and energy saving. The compatibility between traditional phase change materials and building materials is too bad to combine in building energy conservation. Therefore, the new phase change materials have become a research focus in the field of phase change energy storage in buildings. In the paper, the research progress of phase change materials in recent years and the optimization and application of passive building energy-saving are reviewed.

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Yang, Guijun, Yoon-Ji Yim, Ji Won Lee, Young-Jung Heo, and Soo-Jin Park. "Carbon-Filled Organic Phase-Change Materials for Thermal Energy Storage: A Review." Molecules 24, no. 11 (May 29, 2019): 2055. http://dx.doi.org/10.3390/molecules24112055.

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Phase-change materials (PCMs) are essential modern materials for storing thermal energy in the form of sensible and latent heat, which play important roles in the efficient use of waste heat and solar energy. In the development of PCM technology, many types of materials have been studied, including inorganic salt and salt hydrates and organic matter such as paraffin and fatty acids. Considerable research has focused on the relationship between the material structure and energy storage properties to understand the heat storage/emission mechanism involved in controlling the energy storage performance of materials. In this study, we review the application of various carbon-filled organic PCMs in the field of heat storage and describe the current state of this research.

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Zhang, Yan, Wei Jie Lin, Rui Yang, Yin Ping Zhang, and Qing Wu Zhang. "Preparation and Thermal Property of Phase Change Material Microcapsules by Phase Separation." Materials Science Forum 561-565 (October 2007): 2293–96. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.2293.

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Compared to conventional single-phase fluids, the latent functionally thermal fluid (LFTF), with phase change particles of μm magnitude in size dispersed in it, shows much greater apparent specific heat and heat transfer rate between the fluid and the duct wall. Therefore, for given heat transportation quantity, the mass flow rate and the pump consumption can be reduced greatly. Due to these, LFTF is a promising material in the fields of heat exchanging. In this paper, phase change material (n-tetradecane) was encapsulated by polymethyl mathacrylate (PMMA), polystyrene (PS) and blend of them by internal phase separation method to form microcapsule of 1~2μm in size. The chemical structures were demonstrated by using Fourier transform infrared spectroscopy (FTIR). The core-shell structure was observed using phase contrast microscope. Differential scanning calometry (DSC) results indicated that the phase change enthalpy of the containing 75wt% n-tetradecane as core material reaches 150.7 J/g.

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Ternik, Primoz, Matej Zadravec, and Rebeka Rudolf. "Numerical analysis of the NiTi solidification process influence of thermal conductivity." Science of Sintering 49, no. 1 (2017): 39–49. http://dx.doi.org/10.2298/sos1701039t.

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The present study deals with the numerical analysis of the solidification process of a NiTi binary alloy. The physical medium is taken as an incompressible fluid where the heat is transferred by conduction and convection, including the thermal phase change phenomenon. The energy equation, which includes both convection-diffusion heat transfer and a mushy region for the phase-change (solidification), is modelled by using an enthalpy-based formulation. The numerical approach is based on the finite volume method in body fitted coordinates with a PISO scheme to couple the pressure and velocity fields. The results are presented for the temperature field, as well as for the NiTi mass fraction during the solidification process.

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Brodeur, Sheri A., Wayne Huebner, James P. Runt, and Robert E. Newnham. "Phase change materials for thermal stabilization of composite thermistors." Journal of Materials Research 6, no. 1 (January 1991): 175–82. http://dx.doi.org/10.1557/jmr.1991.0175.

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The objective of this investigation was to develop a triphasic PTC thermistor composite which incorporated a phase capable of absorbing heat at a critical temperature, and thus limiting deleterious effects associated with thermal runaway. The system chosen for study was pentaerythritol incorporated into a carbon black–polyethylene thermistor system. Pentaerythritol exhibits a first order tetragonal to cubic phase transition at 185 °C, with a 1.87 to 3.18 J/°C · g change in specific heat and a 425 J/cm3 heat of transition. Composites with room temperature resistivities as low as 0.1 Ω · m, a PTCR effect of up to six orders of magnitude, and reproducible temperature-cycling behavior were developed. The pentaerythritol introduced thermal delays up to 7 min at 185 °C and substantially increased the electrical and mechanical stability of the composites with temperature and voltage cycling. High fields imparted irreversible effects in these composites as reflected by an increase in the room temperature and high temperature resistivity.

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Zhang, Bo Bo, Yu Ming Xing, and Qiang Sheng. "Numerical Simulation of Two Phase Change Materials Melting Process." Advanced Materials Research 1049-1050 (October 2014): 94–100. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.94.

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Phase change thermal control technology has gained increasing focus as an emerging technology for the thermal control of spacecraft. This literature focused on melting process inside a latent heat energy storage filled with phase change material (PCM) by numerical simulation. A matrix-based enthalpy porosity theory in a three-dimensional finite volume discretization is simulated. The temperature distribution during the melting process of PCM Cerrolow-136 and CH3COONa·3H2O is obtained, based on which the thermal control function and energy storage capacity is compared. The results show that Cerrolow-136 has better performance. In different states of phase change, the temperature distribution of Cerrolow-136 is fairly uniform. Thermal control face's temperature of Cerrolow-136 is closer to phase transition temperature. In the same heat flux of 3000 W/m2, The whole process of thermal control temperature getting to 80°C for Cerrolow-136 is longer. Cerrolow-136, for its excellent characteristics, has potentially broad application in the fields of latent heat energy storage and space vehicle electronics.

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Yun, Haoran, and Xingxiang Zhang. "Fabrication and characterization of hexadecyl acrylate cross-linked phase change microspheres." e-Polymers 20, no. 1 (March 2, 2020): 69–75. http://dx.doi.org/10.1515/epoly-2020-0008.

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AbstractMicrospheres with phase change properties were fabricated by polymerization of hexadecyl acrylate (HA) and different cross-linking agents. The samples were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA). The results show that, the samples that added cross-linking agents have a smooth surface and the latent heat of them is different. The experiments show that all of the cross-linked copolymer shells can be made into temperature controlled release microspheres. These materials can be potentially applied in the field of thermal energy storage. β-tricalcium phosphate was encapsulated in microspheres to obtain one with a fast release effect. It will effectively promote bone conduction when these microspheres were implanted into a bone defect. This microsphere can be used for orthopedic implant or coating of instrument in the future.

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Hu, Qinghong, Yan Chen, Jiaoling Hong, Shan Jin, Guangjin Zou, Ling Chen, and Da-Zhu Chen. "A Smart Epoxy Composite Based on Phase Change Microcapsules: Preparation, Microstructure, Thermal and Dynamic Mechanical Performances." Molecules 24, no. 5 (March 6, 2019): 916. http://dx.doi.org/10.3390/molecules24050916.

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Microencapsulated phase change materials (MicroPCMs)-incorporated in epoxy composites have drawn increasing interest due to their promising application potential in the fields of thermal energy storage and temperature regulation. However, the study on the effect of MicroPCMs on their microstructure, thermal and viscoelastic properties is quite limited. Herein, a new type of smart epoxy composite incorporated with polyurea (PU)-shelled MicroPCMs was fabricated via solution casting method. Field emission-scanning electron microscope (FE-SEM) images revealed that the MicroPCMs were uniformly distributed in the epoxy matrix. The thermal stabilities, conductivities, phase change properties, and dynamic mechanical behaviors of the composite were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), thermal constant analyzer and infrared thermography. The results suggested that the heat storage ability of the composites was improved by increasing the MicroPCMs content. The thermal stability of MicroPCMs was found to be enhanced after incorporation into the matrix, and the MicroPCMs-incorporated epoxy composites showed a good thermal cycling reliability. Moreover, the incorporation of MicroPCMs reduced the composites’ storage modulus but increased the glass transition temperature (Tg) as a result of their restriction to the chain motion of epoxy resin. Besides, a less marked heating effect for the composite was explored through infrared thermography analysis, demonstrating the good prospect for temperature regulation application.

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Chen, Gang, and Li Xia Wan. "Research and Application of Thermal Storage with Phase Change Materials." Advanced Materials Research 250-253 (May 2011): 3541–44. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3541.

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The types and characteristics of phase change energy storage materials were introduced ，and the current research of thermal storage with PCMS is summarized in the paper. Meanwhile the influence of stability, corrosion, phase segregation, sub-cooling, and encapsulation of phase change materials on heat storage were presented also. The applications and prospects of PCMS used in many fields were summarized in the end of the paper.

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Ciulla, Giuseppina, Valerio Lo Brano, Antonio Messineo, and Giorgia Peri. "A NUMERICAL SOLUTION THAT DETERMINES THE TEMPERATURE FIELD INSIDE PHASE CHANGE MATERIALS: APPLICATION IN BUILDINGS." Journal of Civil Engineering and Management 19, no. 4 (September 2, 2013): 518–28. http://dx.doi.org/10.3846/13923730.2013.778212.

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The use of novel building materials that contain active thermal components would be a major advancement in achieving significant heating and cooling energy savings. In the last 40 years, Phase Change Materials or PCMs have been tested as thermal mass components in buildings, and most studies have found that PCMs enhance the building energy performance. The use of PCMs as an energy storage device is due to their relatively high fusion latent heat; during the melting and/or solidification phase, a PCM is capable of storing or releasing a large amount of energy. PCMs in a wall layer store solar energy during the warmer hours of the day and release it during the night, thereby decreasing and shifting forward in time the peak wall temperature. In this paper, an algorithm is presented based on the general Fourier differential equations that solve the heat transfer problem in multi-layer wall structures, such as sandwich panels, that includes a layer that can change phase. In detail, the equations are proposed and transformed into formulas useful in the FDM approach (finite difference method), which solves the system simultaneously for the temperature at each node. The equation set proposed is accurate, fast and easy to integrate into most building simulation tools in any programming language. The numerical solution was validated using a comparison with the Voller and Cross analytical test problem.

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Liu, Xiao Hong, Zi Ye Ling, Peng Sun, Xiao Ming Fang, Tao Xu, and Zheng Guo Zhang. "Experimental Study and Numerical Simulation on Thermal Energy Storage Characteristics of Composite Phase Change Materials in Annular Space of Vertical Double-Pipe Heat Exchanger." Advanced Materials Research 1053 (October 2014): 143–49. http://dx.doi.org/10.4028/www.scientific.net/amr.1053.143.

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Experimental system on thermal energy storage characteristics of phase change materials (PCMs) in annular space of a vertical double-pipe heat exchanger was set up. The thermal storage performance of paraffin and paraffin/expanded graphite composite PCM with the mass fraction of 70% paraffin was compared. The Fluent software was used to simulate the temperature field of the composite PCM during the thermal storage process. The results show that, for the paraffin, in the sensible heat storage phase, because the heat transfer process is controlled by the heat conduction, the temperature in paraffin gradually reduces from the inside to the outside of the annular space. But for the phase change thermal storage phase, solid-liquid phase change heat transfer is controlled by natural convection and the effect of buoyancy, the temperature in paraffin reduces from top to bottom, from the inside to the outside of the annular space. For the composite PCM, heat transfer is controlled only by the heat conduction process, both the sensible and latent heat storage process, the temperature in the composite PCM decreases from bottom to top, from inside to outside of the annular space. As the thermal conductivity of composite PCM is 15.65 times of paraffin, the thermal energy storage time is shortened by 86.6% than paraffin. The temperature fields of composite PCM in different time are obtained by numerical simulation method, the measured temperatures and simulation results are in good agreement.

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Xia, Wei, Heng Xue Xiang, Wen Ping Chen, Yan Li, Wei Chen, Li Jun Chen, Jie Zhao, and Mei Fang Zhu. "Cellulose/Paraffin Composite Fibers for Thermal Energy Storage and Temperature Regulation." Materials Science Forum 898 (June 2017): 2318–28. http://dx.doi.org/10.4028/www.scientific.net/msf.898.2318.

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Cellulose is a good bio-based material for rich resources and recyclability. Paraffin is widely used in the field of energy storage and temperature regulation due to its excellent heat storage properties and mature preparation technology. In this paper, the cellulose fibers with energy storage and temperature regulation were prepared by wet spinning process using paraffin as phase change material. Field Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA) were utilized to characterize the morphology structure, crystalline properties, phase transition properties and heat resistance of fibers and so on. The results showed that the fiber surface without holes and paraffin was uniformly distributed in the cellulose matrix, and paraffin was not easily overflow during the process of phase change. Paraffin and cellulose substrate had good compatibility due to the interaction of hydrogen bonding, and 30% of paraffin did not cause a significant impact on the degree of crystallinity and thermal stability of cellulose fibers. Enthalpy of the resultant functional fibers could reach 27.44 J/g, and the thermal decomposition temperature was over 300 °C. The fibers possessed the phase change ability and certain mechanical properties. Furthermore, it was found that the fibers still had good resistance to washing under extreme conditions.

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Sarı, Ahmet, Alper Biçer, and Gökhan Hekimoğlu. "Effects of carbon nanotubes additive on thermal conductivity and thermal energy storage properties of a novel composite phase change material." Journal of Composite Materials 53, no. 21 (October 23, 2018): 2967–80. http://dx.doi.org/10.1177/0021998318808357.

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Fatty acids are commonly preferred as phase change materials for passive solar thermoregulation due to their several advantageous latent heat thermal energy storage (LHTES) properties. However, further storage container requirement of fatty acids against leakage problem during heating period and also low thermal conductivity significantly limit their application fields. To overcome these drawbacks of capric acid–stearic acid eutectic mixture as phase change material, it was first impregnated with expanded vermiculite clay by melting/blending method and then doped with carbon nanotubes. The effects of carbon nanotubes additive on the chemical/morphological structures and LHTES properties of the composite phase change material and thermal enhanced change phase change materials were investigated by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis analysis techniques. The differential scanning calorimetry results showed that the form-stable composite phase change materials and thermal enhanced composite phase change materials have melting temperatures in the range of 24.35–24.64℃ and latent heat capacities between 76.32 and 73.13 J/g. Thermal conductivity of the composite phase change materials was increased as 83.3, 125.0 and 258.3% by carbon nanotubes doping 1, 3 and 5 wt%. The heat charging and discharging times of the thermal enhanced -composite phase change materials were reduced appreciably due to the enhanced thermal conductivity without notably influencing their LHTES properties. Furthermore, the thermal cycling test and thermogravimetric analysis findings proved that all fabricated composites had admirable thermal durability, cycling LHTES performance and chemical stability.

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Wang, L., W. Yang, L. Huang, B. Yang, N. Sun, and M. B. Yang. "Effect of thermal gradient field with phase change on crystal morphologies of HDPE during GAIM process." Plastics, Rubber and Composites 39, no. 9 (November 2010): 385–91. http://dx.doi.org/10.1179/174328910x12777566997450.

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Chamkha, Ali J., and Fatih Selimefendigil. "MHD mixed convection of nanofluid due to an inner rotating cylinder in a 3D enclosure with a phase change material." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 10 (October 7, 2019): 3559–83. http://dx.doi.org/10.1108/hff-07-2018-0364.

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Purpose The purpose of this study is to numerically examine the mixed convection of CuO-water nanofluid due to a rotating inner hot circular cylinder in a 3D cubic enclosure with phase change material (PCM) attached to its vertical surface. Heat transfer and fluid flow characteristics were examined for various values of pertinent parameters. Design/methodology/approach Finite element method was used in the numerical simulation. Influence of various pertinent parameters such as Rayleigh number (between 10$^5$ and 10$^6$), Hartmann number (between 0 and 100), angular rotational speed of the cylinder (between −50 and 50), solid nanoparticle volume fraction (between 0 and 0.04) and PCM parameters (height-between 0.2H and 0.8H, thermal conductivity ratio- between 0.1 and 10) on the convective heat transfer characteristics are numerically studied. Findings It was observed that local heat transfer variations along the hot surface differ significantly for the cases with and without magnetic field where three distinct hot spots of peak Nusselt number are established when magnetic field is imposed. The average Nusselt number enhancement with the nanofluid at the highest particle volume fraction is 52.85 per cent at Hartmann number of 100, whereas its value is 39.76 per cent for the case in the absence of magnetic field. When the inner cylinder rotates, flow and thermal fields are affected within the cavity. The local heat transfer variations spread over the hot surface with cylinder rotation and 16.43 per cent of reduction in the average heat transfer is obtained with counter-clockwise rotation at 100 rad/sec. An enhancement in the PCM height and a reduction in the thermal conductivity of the PCM result in average heat transfer deterioration for the 3D cavity. The amount of the reduction is 43 per cent when the PCM height is increased from 0.2H to 0.8H, whereas 19.10 per cent enhancement in the heat transfer is achieved when thermal conductivity ratio (PCM) to the base fluid is increased from 0.1 to 10. Originality/value Such configurations can be designed for convection control, and in our case, various methods are available. Some of the investigated methods can be used in applications where magnetic field already exists. Convection control study in 3D cavity gives more realistic results as compared to 2D configurations, and results of the current investigation may be used for the design, optimization and flow control of many thermal applications involving magnetic field effects.

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Ivanova, A. A. "Calculation of Phase-Change Boundary Position in Continuous Casting." Archives of Foundry Engineering 13, no. 4 (December 1, 2013): 57–62. http://dx.doi.org/10.2478/afe-2013-0082.

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Abstract The problem of determination of the phase-change boundary position at the mathematical modeling of continuous ingot temperature field is considered. The description of the heat transfer process takes into account the dependence of the thermal physical characteristics on the temperature, so that the mathematical model is based on the nonlinear partial differential equations. The boundary position between liquid and solid phase is given by the temperatures equality condition and the Stefan condition for the two-dimensional case. The new method of calculation of the phase-change boundary position is proposed. This method based on the finite-differences with using explicit schemes and on the iteration method of solving of non-linear system equations. The proposed method of calculation is many times faster than the real time. So that it amenable to be used for model predictive control of continuous semifinished product solidification.

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Zhao, Long Zhi, Xin Yan Jiang, Ming Juan Zhao, and Jian Zhang. "Phase-Field Simulation of Dendrite Growth of Magnesium Alloy under Non-Isothermal Solidification." Advanced Materials Research 848 (November 2013): 231–35. http://dx.doi.org/10.4028/www.scientific.net/amr.848.231.

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The phase-field model was built by coupling with the concentration field and temperature field,The dendrite growth process of Magnesium alloy was simulated under the different anisotropic strength and different undercooling.The results show that with the enlarge of anisotropic strength, dendritic morphology change from seaweed-like to snow-like, trunk grows along the optimal direction,and the secondary dendrite arm grow along the most optimize direction as well; With undercooling increasing, the more coarse primary dendrite arm, the more developed secondary dendrite arm, dendrites around the thermal diffusion layer becomes thinner,and dendrite tip’s thermal diffusion layer is thinner than the dendrite roots,but segregation phenomenon decreases slowly. When Δ=1.0, the grain will directly generate cellular dendrite and it does’t appear segregation phenomenon

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Ribezzo, Alessandro, Matteo Fasano, Luca Bergamasco, Luigi Mongibello, and Eliodoro Chiavazzo. "Multi-Scale Numerical Modelling for Predicting Thermo-Physical Properties of Phase-Change Nanocomposites for Cooling Energy Storage." Tecnica Italiana-Italian Journal of Engineering Science 65, no. 2-4 (July 30, 2021): 201–4. http://dx.doi.org/10.18280/ti-ijes.652-409.

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One major limitation of phase-change materials (PCM) for thermal energy storage comes from their poor thermal conductivity hindering heat transfer process and power density. Nanocomposites PCMs, where highly conductive nanofillers are dispersed into PCM matrices, have been exploited in the past decades as novel latent heat storage materials with enhanced thermal conductivity. A computational model based on continuum simulations capable to link microscopic characteristics of nanofillers and the bulk PCM with the macroscopic effective thermal conductivity of the resulting nanocomposite is the aim of this work. After preliminary mean-field simulations investigating the impact of the nanofiller aspect ratio on the thermal conductivity of the nanocomposite, finite element simulations at reduced aspect ratios have been performed with corrected thermal conductivity values of the filler, to take into account the thermal interface resistances between fillers and matrix. Finally, the thermal conductivity at the actual aspect ratios has been extrapolated by the results obtained at reduced aspect ratios thus saving computational time and meshing efforts. This method has been validated through comparison against previous literature evidence and new experimental characterizations of nanocomposite PCMs.

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Jia, Hao, Si Yu Yuan, He Liu, Shan Hu Tong, Li Hua Fu, and Hua Song. "Study on the Temperature Field of U75V Rail in the Cooling Process Based on ANSYS." Applied Mechanics and Materials 300-301 (February 2013): 1099–109. http://dx.doi.org/10.4028/www.scientific.net/amm.300-301.1099.

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Uneven distribution of temperature is one of the important factors which influences heavy rail bending changes during the cooling process. Through the research of temperature field can reasonable analysis the heavy rail bending change rule, so it is necessary to study the temperature change rule during heavy rail cooling process. This paper adopts finite element analysis software ANSYS to set up three-dimensional models of U75V heavy rail and the cooling bed, and numerical simulate the cooling process. In which, it is studied the temperature changing rules and its distribution rules, emphatically analyzed temperature changing rule during the phase transition phase, and got the temperature changing rules and distribution rules in final cooling time. Especially, it is considered that the heavy rail placed on its side, the latent heat of phase transition and thermal radiation. This research can provide the theory basis and the advisory opinion on the formulation of cooling technological parameters and preflex regulations of the rail.

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Journal articles on the topic 'Thermal field with phase change'

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