Numerical and Experimental Investigation of Phase Change Heat Transfer in the Presence of Rayleigh–Benard Convection

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Mohammad Parsazadeh ◽  
Xili Duan
Keyword(s):  
Nusselt Number ◽  
Phase Change ◽  
Local Heat ◽  
Liquid Interface ◽  
Interface Location ◽  
Local Heat Flux ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Abstract This research investigates the melting rate of a phase change material (PCM) in the presence of Rayleigh–Benard convection. A scaling analysis is conducted for the first time for such a problem, which is useful to identify the parameters affecting the phase change rate and to develop correlations for the solid–liquid interface location and the Nusselt number. The solid–liquid interface and flow patterns in the liquid region are analyzed for PCM in a rectangular enclosure heated from bottom. Numerical and experimental results both reveal that the number of Benard cells is proportional to the ratio of the length of the rectangular enclosure over the solid–liquid interface location (i.e.,, the liquified region aspect ratio). Their effect on the local heat flux is also analyzed as the local heat flux profile changes with the solid–liquid interface moving upward. The variations of average Nusselt number are obtained in terms of the Stefan number, Fourier number, and Rayleigh number. Eventually, the experimental and numerical data are used to develop correlations for the solid–liquid interface location and average Nusselt number for this type of melting problems.

scholarly journals Numerical Solution of Heat Transfer Process in PCM Storage Using Tau Method

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
B. Heydari ◽  
F. Talati
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Numerical Approach ◽  
Heat Transfer Process ◽  
Liquid Interface ◽  
Tau Method ◽  
Two Dimensional ◽  
Interface Location ◽  
Solid Liquid Interface ◽  
Solid Liquid

Thermal energy storage units that utilize phase change materials have been widely employed to balance temporary temperature alternations and store energy in many engineering systems. In the present paper, an operational approach is proposed to the Tau method with standard polynomial bases to simulate the phase change problems in latent heat thermal storage systems, that is, the two-dimensional solidification process in rectangular finned storage with a constant end-wall temperature. In order to illustrate the efficiency and accuracy of the present method, the solid-liquid interface location and the temperature distribution of the fin for three test cases with different geometries are obtained and compared to simplified analytical results in the published literature. The results indicate that using a two-dimensional numerical approach can predict the solid-liquid interface location more accurately than the simplified analytical model in all cases, especially at the corners.

scholarly journals Approximate Analytical Solution for One-Dimensional Solidification Problem of a Finite Superheating Phase Change Material Including the Effects of Wall and Thermal Contact Resistances

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Hamid El Qarnia ◽  
Fayssal El Adnani ◽  
El Khadir Lakhal
Keyword(s):  
Analytical Solution ◽  
Phase Change ◽  
Phase Change Material ◽  
Liquid Interface ◽  
Solid Shell ◽  
Interface Position ◽  
Temperature Distributions ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Change Material

This work reports an analytical solution for the solidification of a superheating phase change material (PCM) contained in a rectangular enclosure with a finite height. The analytical solution has been obtained by solving nondimensional energy equations by using the perturbation method for a small perturbation parameter: the Stefan number,ε. This analytical solution, which takes into account the effects of the superheating of PCM, finite height of the enclosure, thickness of the wall, and wall-solid shell interfacial thermal resistances, was expressed in terms of nondimensional temperature distributions of the bottom wall of the enclosure and both PCM phases, and the dimensionless solid-liquid interface position and its dimensionless speed. The developed solution was firstly compared with that existing in the literature for the case of nonsuperheating PCM. The predicted results agreed well with those published in the literature. Next, a parametric study was carried out in order to study the impacts of the dimensionless control parameters on the dimensionless temperature distributions of the wall, the solid shell, and liquid phase of the PCM, as well as the solid-liquid interface position and its dimensionless speed.

Numerical Simulation of the Effect of the Size of Nanoparticles on the Solidification Process of Nanoparticle-Enhanced Phase Change Materials

2012 ◽  
Author(s):  
Yousef M. F. El Hasadi ◽  
J. M. Khodadadi
Keyword(s):  
Particle Size ◽  
Phase Change ◽  
Phase Change Materials ◽  
Concentration Field ◽  
Solidification Process ◽  
Liquid Interface ◽  
Constitutional Supercooling ◽  
Fluid Mixture ◽  
Solid Liquid Interface ◽  
Solid Liquid

Nanoparticle-enhanced phase change materials (NEPCM) were proposed recently as alternatives to conventional phase change materials due to their enhanced thermophysical properties. In this study, the effect of the size of the nanoparticles on the morphology of the solid-liquid interface and evolving concentration field, during solidification had been reported. The numerical method that was used is based on the one-fluid-mixture model. The model takes into account the thermal as well as the solutal convection effects. A square cavity model was used in the simulation. The NEPCM that was composed of a suspension of copper nanoparticles in water was solidified from the bottom. The nanoparticles size used were 5 nm and 2 nm. The temperature difference between the hot and cold sides was 5 degrees centigrade and the loading of the nanoparticles that have been used in the simulation was 10% by mass. The results obtained from the model were compared with those existing in the literature, and the comparison was satisfactory. The solid-liquid interface for the case of NEPCM with 5 nm particle size was almost planar throughout the solidification process. However, for the case of the NEPCM with particle size of 2 nm, the solid-liquid interface evolved from a planar stable shape to an unstable dendritic shape, as the solidification process proceeded with time. This was attributed to the constitutional supercooling effect. It has been observed that the constitutional supercooling effect is more pronounced as the particle size decreases. Furthermore, the freezing time increases as the particle size decreases.

Large-Scale Experimental Study of a Phase Change Material: Shape Identification for the Solid–Liquid Interface

2015 ◽  
Vol 36 (10-11) ◽  
pp. 2897-2915 ◽  
Author(s):  
Soumaya Kadri ◽  
Belgacem Dhifaoui ◽  
Yvan Dutil ◽  
Sadok Ben Jabrallah ◽  
Daniel R. Rousse
Keyword(s):  
Experimental Study ◽  
Phase Change ◽  
Phase Change Material ◽  
Large Scale ◽  
Liquid Interface ◽  
Shape Identification ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Change Material

Transient Freezing of Liquids in Forced Flow Inside Circular Tubes

1969 ◽  
Vol 91 (3) ◽  
pp. 385-389 ◽  
Author(s):  
M. N. O¨zis¸ik ◽  
J. C. Mulligan
Keyword(s):  
Solid Phase ◽  
Freezing Temperature ◽  
Local Heat ◽  
Liquid Interface ◽  
Forced Flow ◽  
Transfer Rates ◽  
Tube Wall Temperature ◽  
Temperature Constant ◽  
Solid Liquid Interface ◽  
Solid Liquid

The transient freezing of a liquid flowing inside a circular tube is investigated analytically under the assumption of a constant tube wall temperature which is lower than the freezing temperature, constant properties, a slug-flow velocity profile and quasisteady state heat conduction in the solid phase. The variation of the local heat flux and the profile of the solid-liquid interface during freezing has been determined as a function of time and position along the tube. The analysis produced steadystate heat transfer rates and profiles for the solid-liquid interface which agreed well with experiments.

Phase Change Heat Transfer During Melting and Resolidification of Melt Around Cylindrical Heat Source(s)/Sink(s)

1989 ◽  
Vol 111 (1) ◽  
pp. 43-49 ◽  
Author(s):  
K. Sasaguchi ◽  
R. Viskanta
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Liquid Interface ◽  
Cylinder Surface ◽  
Storage Unit ◽  
Energy Storage Unit ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Change Material

Melting and resolidification of a phase change material around two cylindrical heat exchangers spaced vertically have been investigated experimentally. Experiments have been performed to examine the effects of the cylinder surface temperatures on heat transfer during the melting and freezing cycle. The processes have been clarified on the basis of observations of timewise variations in the solid/liquid interface and of temperature distribution measurements in the phase change material. The results show that the solid/liquid interface contour during the melting and resolidification of the liquid from the upper cylinder is greatly affected by the surface temperature of the lower cylinder. The results show that multiple liquid regions may develop in the phase change material around the embedded heat sources/sinks, and the temperature swings and melting and freezing periods need to be selected properly in order to effectively utilize the phase change material in a latent heat energy storage unit.

Phase-Change in Finite Slabs With Time-Dependent Convective Boundary Conditions

Volume 3 ◽  
2004 ◽  
Author(s):  
Anand P. Roday ◽  
Michael J. Kazmierczak
Keyword(s):  
Phase Change ◽  
Change Process ◽  
Initial Conditions ◽  
Convective Boundary Condition ◽  
Liquid Interface ◽  
Convective Boundary ◽  
Phase Change Process ◽  
The Right ◽  
Solid Liquid Interface ◽  
Solid Liquid

The heat balance integral method is used to solve one-dimensional phase-change problem in a finite slab with time-dependent convective boundary condition, [T∞,1(t)], applied at the left face. The temperature, T∞,1(t), decreases linearly with time; the other face of the slab is subjected to a constant convective boundary condition with T∞,2 held fixed at the ambient temperature. Two initial conditions are investigated: temperature of the solid below the melting point (subcooled), and initially at the fusion temperature (Tf). The temperature, T∞,1(t) at time t = 0 is so chosen such that convective heating takes place and the slab begins to melt (i.e., T∞,1(0)> Tf> T∞,2). Thus the solid-liquid interface proceeds forward to the right. As time continues, and T∞,1(t) decreases with time, the phase-change front slows, stops, and may even reverse direction. Hence this problem features sequential melting and freezing of the slab with partial penetration of the solid-liquid front before reversal of the phase-change process. It should, however, be noted that the study is limited to only one solid-liquid interface at any given time during the phase-change process (either melting or freezing) and that slight subcooling of the melt is allowed. The effect of varying the Biot number at the right face of the slab, for both the initial conditions, is also investigated to determine its impact on the growth/recession of the solid-liquid interface. Temperature profiles in both regions (liquid and solid) are reported in detail. The effect of a slower decay rate of T∞,1(t) on the phase-change process is also analyzed for the initial condition of the slab being at the fusion temperature.

Sign in / Sign up

Export Citation Format

Share Document