scholarly journals Numerical Study of the Thermal Behavior of a Composite Phase Change Material (PCM) Room

2018 ◽  
Vol 8 (2) ◽  
pp. 2663-2667 ◽  
Author(s):  
N. Ben Khedher
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Indoor Temperature ◽  
Three Phase ◽  
Chloride Hexahydrate ◽  
Hot Weather ◽  
Building Walls

In this study, thermal performance of building walls integrated with phase change materials (PCM) was evaluated in terms of indoor temperature reduction and heat transfer time delay. PCM was incorporated as thin layer placed longitudinally within walls. The thermal performance of a room with and without PCM was evaluated numerically. The developed model is based on the enthalpy formulation for PCM melting and solidification, which is solved by an implicit finite difference method. The effect of PCM type on heat gain indoors was studied. Three phase change materials (n-octadecane, n-eicosane and calcium chloride hexahydrate) were tested in hot weather. Results showed that octadecane is the best in ensuring an indoor temperature close to 27 °C for the test room. Moreover, optimal thickness of the PCM layer within the walls is critical for heat transfer reduction and management and should be carefully chosen.

Natural Convection in an Enclosure With Blend of Micro Encapsulated Phase Change Materials

2013 ◽  
Author(s):  
Yasmin Khakpour ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Thermal Expansion ◽  
Natural Convection ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Pure Water ◽  
Operating Conditions ◽  
Effective Density

This numerical study investigates the effect of using a blend of micro-encapsulated phase change materials (MEPCMs) on the heat transfer characteristics of a liquid in a rectangular enclosure driven by natural convection. A comparison has been made between the cases of using single component MEPCM slurry and a blend of two-component MEPCM slurry. The natural convection is generated by the temperature difference between two vertical walls of the enclosure maintained at constant temperatures. Each of the two phase change materials store latent heat at a specific range of temperatures. During phase change of the PCM, the effective density of the slurry varies. This results in thermal expansion and hence a buoyancy driven flow. The effects of MEPCM concentration in the slurry and changes in the operating conditions such as the wall temperatures compared to that of pure water have been studied. The MEPCM latent heat and the increased volumetric thermal expansion coefficient during phase change of the MEPCM play a major role in this heat transfer augmentation.

Solid/Liquid Phase Change Heat Transfer in Latent Heat Thermal Energy Storage

2009 ◽  
Author(s):  
D. Zhou ◽  
C. Y. Zhao
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Calcium Chloride ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Metal Foams ◽  
Chloride Hexahydrate

Phase change materials (PCMs) have been widely used for thermal energy storage systems due to their capability of storing and releasing large amounts of energy with a small volume and a moderate temperature variation. Most PCMs suffer the common problem of low thermal conductivity, being around 0.2 and 0.5 for paraffin and inorganic salts, respectively, which prolongs the charging and discharging period. In an attempt to improve the thermal conductivity of phase change materials, the graphite or metallic matrix is often embedded within PCMs to enhance the heat transfer. This paper presents an experimental study on heat transfer characteristics of PCMs embedded with open-celled metal foams. In this study both paraffin wax and calcium chloride hexahydrate are employed as the heat storage media. The transient heat transfer behavior is measured. Compared to the results of pure PCMs samples, the investigation shows that the additions of metal foams can double the overall heat transfer rate during the melting process. The results of calcium chloride hexahydrate are also compared with those of paraffin wax.

Thermal Performance of a Heat Storage Module Using Calcium Chloride Hexahydrate

1984 ◽  
Vol 106 (1) ◽  
pp. 106-111 ◽  
Author(s):  
D. Dietz
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Phase Change ◽  
Calcium Chloride ◽  
Thermal Performance ◽  
Heat Storage ◽  
Heat Transfer Area ◽  
Transfer Rates ◽  
Chloride Hexahydrate ◽  
Change Material

The thermal performance of an air-heated/cooled, phase-change, heat stoage module was tested and evaluated. The module (rated at 38.7 kWh) consist of 130 vertically oriented tubes filled with 729 kg (1607 lb) of calcium chloride hexahydrate and enclosed in a rectangular box. Heat transfer rates measured during charging and discharging decreased with time as a result of decreasing effective heat transfer area and increasing thermal resistance of the phase-change material. These two dominant effects are included in a proposed mathematical model that predicted the experimental data.

Phase Change Process Inside a Small-radii Cylinder Subjected to Cyclic Convective Boundary Conditions: a Numerical Study

2021 ◽  
Author(s):  
Yousef Kanani ◽  
Avijit Karmakar ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Phase Change ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Convective Boundary Condition ◽  
Freezing Process ◽  
Fourier Number ◽  
Two Phase ◽  
Convective Boundary

Abstract We numerically investigate the melting and solidi?cation behavior of phase change materials encapsulated in a small-radii cylinder subjected to a cyclic convective boundary condition (square wave). Initially, we explore the effect of the Stefan and Biot numbers on the non-dimensionalized time required (i.e. reference Fourier number Tref ) for a PCM initially held at Tcold to melt and reach the cross?ow temperature Thot. The increase in either Stefan or Biot number decreases Tref and can be predicted accurately using a correlation developed in this work. The variations of the PCM melt fraction, surface temperature, and heat transfer rate as a function of Fourier number are reported and analyzed for the above process. We further study the effect of the cyclic Fourier number on the periodic melting and freezing process. The melting or freezing front initiates at the outer periphery of the PCM and propagates towards the center. At higher frequencies, multiple two-phase interfaces are generated (propagating inward), and higher overall heat transfer is achieved as the surface temperature oscillates in the vicinity of the melting temperature, which increases the effective temperature difference driving the convective heat transfer.

Liquid Film Evaporation in the Presence of Micro Encapsulated Phase Change Materials: A Numerical Study

2013 ◽  
Author(s):  
Yasmin Khakpour ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Phase Change ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Finite Thickness ◽  
Operating Conditions ◽  
Evaporation Process ◽  
Constant Wall Temperature ◽  
Film Evaporation

This paper numerically investigates the flow and heat transfer characteristics of a slurry of micro encapsulated phase change materials (MEPCM) and R134a in the presence of film evaporation. The numerical domain is comprised of a minichannel in contact with a finite thickness solid zone with constant wall temperature. During the evaporation process, the concentration of MEPCM in the slurry increases, resulting in a continuous variation of effective thermal properties of the slurry. The effect of PCM concentration on the evolution of the liquid film thickness under different operating conditions along with the variation of the local heat transfer coefficients has been studied. A user defined function has been developed to incorporate the evaporation process by introducing the mass and energy source terms for the evaporation process as well as the variation of the MEPCM concentration along the channel.

Numerical Study of Heat Transfer Characteristics of Liquid Flow in a Microtube With Blend of Micro Phase Change Materials

2012 ◽  
Author(s):  
Yasmin Khakpour ◽  
Jamal Seyed Yagoobi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Liquid Flow ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Finite Thickness ◽  
Local Heat Transfer ◽  
Outer Wall ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

This numerical investigation explores the heat transfer characteristics of liquid flow with two-component (blend) micro phase change materials (MPCM) and compares them with those of a single component MPCM slurry. The numerical domain is comprised of an axisymmetric micro-tube in contact with a finite-thickness solid zone and a constant heat flux applied on the solid outer wall. The ultimate objective is to demonstrate the tunability of PCM fluid’s thermal energy properties when the phase transition temperatures of the PCMs are chosen within a range required for a specific application. This is because different pure PCM materials store latent heat at a specific range of temperatures. The MPCM slurry flow does not reach a fully developed condition as long as the MPCM particles experience phase change in the developing region. The local heat transfer coefficient strongly depends on the corresponding location of the melting zone interface.

Numerical study on the effect of phase change materials on heat transfer in asphalt concrete

2018 ◽  
Vol 133 ◽  
pp. 140-150 ◽  
Author(s):  
Zakariaa Refaa ◽  
Muhammad Rafiq Kakar ◽  
Anastasia Stamatiou ◽  
Jörg Worlitschek ◽  
Manfred N. Partl ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Asphalt Concrete ◽  
Phase Change Materials ◽  
Numerical Study
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