A Simplified Model for Encapsulated Phase Change Material

1999 ◽  
Author(s):  
Linda J. Hayes ◽  
Michael A. Spieker ◽  
Eugene H. Wissler ◽  
David P. Colvin
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Thermal Management ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Flow In Porous Media ◽  
Simplified Model ◽  
Encapsulated Phase Change Material ◽  
Change Material ◽  
Conductive Media

Abstract One of the emerging technologies of this decade is macroencapsulated phase change materials (PCM), which is being developed to provide significantly enhanced thermal management for coolants, textile fibers, foams, composites and coatings with applications to avionics, spacesuits, machine coolants, apparel, packaging, and agriculture (Kaska and Chen, 1985, Colvin and Mulligan 1989). The encapsulated PCM is embedded or suspended in a conductive media. The characteristics of the capsules, the phase change material and the conductive media can be designed so as to provide enhanced thermal management in a wide variety of applications. The traditional way to model this system is to take a macroscopic view of the entire system, to use a volume averaged value for the release of latent heat from the PCM and to incorporate this term into the standard heat conduction equation. We propose a simplified model which has its origins in flow in porous media. The system is modeled with two components, the underlying conductive material and the phase change capsules. The amount of latent heat released from the PCM capsules is determined by the local temperature in the capsules, which can differ from the temperature in the conducting media. This model closely represents the physical systems which are being modeled Numerical results using this model are compared to experimental data from a garment layer which is constructed using macroencapsulated PCM capsules.

scholarly journals Analysis on the Improvement of Thermal Performance of Phase Change Material Ba (OH)2·8H2O

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7761
Author(s):  
Xiaohui Lu ◽  
Xiaoxue Luo ◽  
Shibo Cao ◽  
Changzhen Zou
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Large Scale ◽  
Phase Change Materials ◽  
Graphite Powder ◽  
Stable Phase ◽  
Heat Conducting ◽  
Supercooling Degree ◽  
Change Material

Benefitting from the characteristics of a high latent heat capacity and stable phase change behavior, phase change materials have widely received concerns in the field of thermodynamic management. Ba(OH)2·8H2O is an ideal phase change material (PCM) in the mid-to-low temperature range, but its large-scale application is still limited by severe supercooling during the nucleation process. In this paper, the experimental analysis and comparison are performed via an Edisonian approach, where Ba(OH)2·8H2O is adopted as an original substrate; BaCO3, CaCl2, NaCl, KH2PO4, and NaOH are selected as nucleating agents; and graphite is used as a heat-conducting agent. The results show that Ba(OH)2·8H2O containing 1.2% BaCO3 and 0.2% graphite powder has the best performance. Compared with pure Ba(OH)2·8H2O, the supercooling degree is reduced to less than 1 °C, the phase change latent heat duration is extended, and the thermal conductivity is significantly improved. Therefore, this study not only provides a reference for the application of Ba(OH)2·8H2O, but can also be used as a guidance for other material modifications.

Setting for the Application of Phase Change Paraffin in Block Masonry

2013 ◽  
Vol 448-453 ◽  
pp. 1308-1311
Author(s):  
Feng Jiang ◽  
Yong Le Hou ◽  
Yong Lin Hu ◽  
Wei Dong Zhu ◽  
Qing Hua Wang
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Liquid Paraffin ◽  
Change Temperature ◽  
Composite Phase Change Material ◽  
Heat Preservation ◽  
Solid Liquid ◽  
Change Material

This paper studies the insulation properties of masonry filling paraffin composite phase change material. With high density polyethylene (HDPE) as wrapping materials and solid-liquid mixing paraffin as phase change materials, solid-liquid mixed paraffin phase change material with different amount of admixture is prepared, and the problem of flowing after paraffin phase change is then solved. The phase change temperature and the phase change latent heat of composite phase change material with different amount of admixture are tested. The results showed that the composite material with 30% of 52 # solid paraffin, 70% of liquid paraffin, 70% of HDPE coating performs best as to the phase transition temperature and latent heat. On this basis, This paper studies the composite phase change wall with phase change materials 0%, 33%, 66% and100%. Results show that the composite phase change material wall’s heat preservation performance has significantly improved. the temperature fluctuation range of internal and external wall surface is 4.2 °C lower than unfilled wall.

Mathematical Model to Describe Thermal Behavior of Phase Change Materials Contained in a Cylindrical Enclosure

2003 ◽  
Author(s):  
Ahmed ElGafy ◽  
Osama Mesalhy ◽  
Khalid Lafdi ◽  
K. Bowman
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Operating Conditions ◽  
High Melting ◽  
Space Applications ◽  
Change Material

Heat transfer processes undergoing liquid-solid phase transformation have been of continuing interest for many researchers. Phase Change Materials, (PCMs); have received great consideration in electronic industry for cooling of electronics and in telecommunication equipment to control internal temperature under emergency operating conditions. High melting temperature materials have been proposed as thermal energy storage mediums in space applications because of their high melting temperatures and latent heat. In the present work, a numerical simulation is developed to predict the thermal performance of a phase change material of high melting point in a cylindrical enclosure. In this simulation the phases are assumed to be homogeneous and a source term, S, arises from melting and solidification processes is considered as a function of the latent heat of fusion and the liquid phase fraction. By introducing the thermo-physical properties of one of those materials, the thermal performance of it as a phase change material is predicted.

scholarly journals Experimental Analysis of the Latent Heat Storage System (LHS) Using Paraffin Wax as Phase Change Material

2021 ◽  
Vol 9 (VIII) ◽  
pp. 234-241
Author(s):  
Mr. Omkar Jadhav
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage System ◽  
High Energy ◽  
Paraffin Wax ◽  
Latent Heat Storage ◽  
Change Material

An experimental study using paraffin wax as a phase change material (PCM) was performed to analyse thermal physiognomies on the latent heat storage system (LHS). The use of phase change materials through latent heat storage is an unusual approach to maintaining thermal energy. There is the advantage of considerably high energy storage and the uniform temperature of the storage process. Tube & shell type heat exchanger (HE) has been used in this experimentation. Water circulates in tubes and around the tube’s paraffin wax as phase change material is filled. The focus is on heating (charging) and cooling (discharging) of PCM (paraffin wax), which is the melting and solidifying of paraffin wax. The temperature distribution in paraffin is studied consistent with the various flow rates of the warmth transfer fluid.

Accelerated long-term assessment of thermal and chemical stability of bio-based phase change materials

2016 ◽  
Vol 40 (4) ◽  
pp. 299-310 ◽  
Author(s):  
Jignesh S Patel ◽  
Elizabeth Gao ◽  
Veera M Boddu ◽  
Larry D Stephenson ◽  
Ashok Kumar
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Chemical Stability ◽  
Phase Change Materials ◽  
Scanning Calorimetry ◽  
Change Material ◽  
Scanning Electron

Thermal energy storage systems incorporated with phase change materials have potential applications to control energy use by building envelopes. However, it is essential to evaluate long-term performance of the phase change materials and cost-effectiveness prior to full-scale implementation. For this reason, we have used the accelerated long-term approach for studying the thermal performance and chemical stability of a commercially available bio-based phase change material during thermal cycling over a simulated period of 20 years. The phase change material was subjected to accelerate thermal aging under controlled environmental conditions. Small samples of the phase change material were periodically removed to measure its latent heat, thermal decomposition, and chemical stability using various analytical methods such as differential scanning calorimetry, thermogravimetry analysis, and infrared spectroscopy. The topographic changes in the phase change material due to the aging process were observed using scanning electron microscopy. The differential scanning calorimetry data indicate a significant reduction of 12% in the latent heat during heating and cooling cycles during the initial 6.2 years remain nearly constant thereafter. The thermogravimetry analysis results showed that the phase change material has excellent thermal stability within the working temperature range and also shows long-term decomposition temperature stability. The Fourier transform infrared spectra of the phase change material indicate absorption of moisture but the phase change material was chemically stable over the duration of accelerated aging cycles. After several aging cycles, the baseline surface morphology appeared to be changed from uniform mix of phase change material with microstructures to segregated microstructures as evidenced by the observation of the scanning electron micrographs.

Sign in / Sign up

Export Citation Format

Share Document