scholarly journals Modelling and Numerical simulation of Nano-enhanced PV-PCM System for Heat Transfer Augmentation from the Panel

2021 ◽  
Vol 2054 (1) ◽  
pp. 012051
Author(s):  
B Charles Divyateja ◽  
K S Unnikrishnan ◽  
B Rohinikumar
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Liquid Fraction ◽  
Energy Conversion Efficiency ◽  
Solid Particles ◽  
Heat Transfer Augmentation ◽  
Solar Radiation Flux ◽  
Direct Energy

Abstract Phase change materials (PCMs) can effectively cool photovoltaic (PV) panels by the passive cooling technique, thereby enhancing its direct energy conversion efficiency. However, generally, PCMs have low thermal conductivity, and different methods can be employed to improve the heat transfer rate. Cooling techniques based on phase change materials (PCMs) enhanced by nano-sized solid particles are very promising. In this paper, a mathematical model is developed to simulate the performance analysis of PV attached with nano-enhanced PCM (NEPCM) integrated with fins and compare the same with that of pure PCM case. The system is oriented in a horizontal position and subjected to constant solar radiation flux of 1000 W/m 2. The PCM selected is RT25HC, and the nanoparticle used is CuO for the numerical study. The effects of volumetric concentrations (0%, 2%, and 4%) and fin number on the performance of the system are investigated numerically. Results show that adding nanoparticles is more effective in no fin case compared to finned cases. The maximum reduction in average PV temperature of 2.02 °C is obtained for no fin case with the nanoparticles’ volumetric concentration of 4%. Further enhancement in liquid fraction and energy storage in NEPCM is also achieved compared to the pure PCM system.

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.

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.

A Numerical Investigation of Constrained Melting of Nanostructure-Enhanced Phase Change Materials in a Rectangular Cavity Heated From Below

2012 ◽  
Author(s):  
Li-Wu Fan ◽  
Liang Zhang ◽  
Zi-Tao Yu ◽  
Xu Xu ◽  
Ya-Cai Hu ◽  
...  
Keyword(s):  
Natural Convection ◽  
Phase Change ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Liquid Fraction ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Rectangular Cavity ◽  
Heat Of Fusion

A numerical study of constrained melting of nanostructure-enhanced phase change materials (NEPCM) consisting of eicosane and various loadings of CNTs in a rectangular cavity heated from below was performed. Assuming that the NEPCM are single-phase PCMs with homogeneous thermophysical properties, the problem was solved using a finite volume method based on the enthalpy-porosity scheme for solid-liquid phase change. The effective thermophysical properties of NEPCM were predicted using the mixture models and empirical equation with respect to the loading of CNTs. Three nominal Grashof numbers corresponding to three sizes of the cavity were considered. Evolutions of the constrained melting processes were presented by means of snapshots of the temperature contour at representative time instants. The melting rates and local heat transfer along the heated bottom were compared quantitatively based on the variations of the instantaneous liquid fraction and average Nusselt number over the bottom during melting, respectively. It was shown that at a given size of the cavity, melting was expedited as more CNTs were introduced. The expediting of melting was mainly attributed to the enhanced thermal conductivity and lowering of latent heat of fusion of NEPCM. The inclusion of CNTs, however, increases considerably the viscosity of melted NEPCM, which in turn leads to less significant natural convection effect during melting. As a result, increase of loading of CNTs was shown to lead to two competing effects. The feasibility of NEPCM in melting is justified when the enhanced heat conduction overweighs the suppressed natural convection.

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

Numerical Study of Phase Change of PCM in Spherical Cavities

2017 ◽  
Vol 372 ◽  
pp. 21-30 ◽  
Author(s):  
Fábio Faistauer ◽  
Petros Rodrigues ◽  
Rejane de Césaro Oliveski
Keyword(s):  
Phase Change ◽  
Melting Temperature ◽  
Wall Temperature ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Liquid Fraction ◽  
Fluid Dynamic ◽  
Melting Process ◽  
Constant Wall Temperature ◽  
Spherical Cavities

This work presents a numerical study of the phase change process of PCM (Phase Change Materials) stored in spherical cavities. The numerical model is two-dimensional and it is composed by the equations of conservation of mass, momentum, energy and volumetric fraction, which are modeled using the enthalpy-porosity technique. The computational mesh is tetrahedral, with refinements on regions that have large thermic and fluid dynamic gradients. The numeric model was validated with result from literature. It was studied the melting process of PCM RT35, RT 55 and RT 82 in spherical cavity with constant wall temperature. Four diameters of spheres D were used (40, 60, 80 and 100 mm) and three temperature differences ΔT (10, 20 and 30 oC) between the wall temperature and the melting temperature of the PCM. Liquid fraction results from the 36 cases studied are presented. It was observed that the time required to reach a certain liquid fraction increases with the diameter and reduces with the increment of ΔT, being possible to predict the fusion time by knowing the characteristic length of the sphere. The largest percentage reduction of the fusion time was obtained with ΔT = 10 oC – 20 oC for all the D considered. The shortest fusion time was obtained with the largest ΔT combined with the smallest D. It is possible to see the dependence of the liquid fraction results in relation with the PCM properties and the its independence in relation its melting temperature, since all the PCM studied presented equal fusion time for the same ΔT and D.

Investigation of the Heat Transfer Process in a PCM During Melting Phase

2014 ◽  
Author(s):  
Mohammad Bashar ◽  
Kamran Siddiqui
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Energy ◽  
Transfer Process ◽  
Phase Change Materials ◽  
Waste Heat ◽  
Liquid Fraction ◽  
Local Heat Transfer ◽  
Heat Transfer Process ◽  
Interface Temperature

Thermal energy storage systems are gaining significance due to their potential use to store renewable energy and waste heat. Phase change materials (PCMs) are considered to be an efficient way to store thermal energy. However, the heat transfer process during the phase change is not well understood. We report on an experimental study conducted to investigate the heat transfer process in a PCM during melting phase. A PCM storage system subjected to bottom heating from a horizontal heated cylinder was considered using wax as the PCM. An imaging technique was used to capture the movement of the solid-liquid interface. Temperature was measured at multiple locations to quantify the heat transfer process. The interface was found to move with a relatively uniform velocity throughout the melting process however, the heat transfer rate was significantly enhanced in the melted (liquid) phase. The local heat transfer coefficient was found to decrease with an increase in the liquid fraction.

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