Heat Transfer Enhancements Using Vibration During Solidification of Paraffin

2010 ◽  
Author(s):  
Johnathan Vadasz ◽  
Josua Meyer ◽  
Saneshan Govender
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Wall Temperature ◽  
Vibration Frequency ◽  
Initial Temperature ◽  
Solidification Process ◽  
Solid Material ◽  
Solidification Temperature ◽  
Change Material

In the current study the effects of vibration on the solidification process of phase change material (PCM) paraffin in a sphere shell are investigated. The amount of PCM used was kept constant during each experiment by using a digital scale to check the weight and a thermocouple to check the consistency of the temperature. A small amount of air was present in the sphere so that the sphere was not filled completely. Commercially available paraffin wax, RT35, was used in the experiments. Experimentations were done on a sphere of 40 mm diameter, wall temperature of 20°C below mean solidification temperature, and consistent initial temperature. A constant vibration frequency of 100 Hz was applied to the setup and results compared with that of no vibration. Samples were taken at different times during the solidification process and compared with respect to solid material present. It was found that the solidification time had been reduced significantly under the vibration. This led to the conclusion that there had been an improvement in heat transfer due to the vibration.

scholarly journals Analytical Study of the Solidification of a Phase Change Material in an Annular Space

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5561
Author(s):  
Zygmunt Lipnicki ◽  
Tomasz Małolepszy
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Solidification Front ◽  
Solidification Process ◽  
Theoretical Research ◽  
Graphical Form ◽  
Annular Space ◽  
Conjugate System ◽  
Change Material

In this study, the process of the solidification of a PCM (phase change material) liquid in an annular space was analytically investigated with the use of a simplified quasi-steady-state model. This model described the phase change phenomenon with the cylindrical solidification front and with the solidification liquid overheated above the solidification temperature. One of the important novelties of the applied model was the determination of the coefficient of the heat transfer between the liquid and the solidified layer on the solidification surface, which was calculated as a function of the location of the solidification front. A method for calculating the variable coefficient of heat transfer on the surface of the solidification front during the solidification process is presented. The contact layer between the cold wall and the solidified layer was incorporated into the model and played an important role. The theoretical analytical method describing the solidification process based on the quasi-steady model was used in the study. Moreover, the main problem considered in this work could be reduced to a conjugate system of differential equations, allowing it to be solved numerically. From this perspective, the influence of various dimensionless parameters on the solidification process could be clearly seen. The obtained numerical results are presented in graphical form. The results of the theoretical research were compared with the experimental research of one of the author’s earlier works and they showed a significant agreement. Finally, the simple analytical approach presented in this work can be used for designing annular heat accumulators.

scholarly journals Vibration Effects on Heat Transfer During Solidification of Paraffin

2011 ◽  
Author(s):  
Johnathan Vadasz ◽  
Josua Meyer ◽  
Saneshan Govender ◽  
Gennady Ziskind
Keyword(s):  
Heat Transfer ◽  
Solidification Process ◽  
Solid Material ◽  
Paraffin Wax ◽  
Solidification Temperature ◽  
Numerical Work ◽  
Enhancement Of Heat Transfer ◽  
Set Up ◽  
Work Done ◽  
Change Material

Previous work looked at the solidification process of PCM (phase change material) paraffin wax. Experimental results were compared with numerical work done in CFD package FLUENT. In the current study, the effects of vibration on heat transfer during the solidification process of PCM in a sphere shell are investigated. Enhancement of heat transfer results in quicker solidification times and desirable mechanical properties of the solid. The amount of PCM used was kept constant during each experiment by using a digital scale to check the weight, and thermocouple to check consistent temperature. A small amount of air was present in the sphere so that the sphere was not filled completely. Commercially available paraffin wax, RT35, was used in the experiments. Experimentations were done on a sphere of 40 mm diameter, wall temperature 20°C below mean solidification temperature, and consistent initial temperature. A vibration frequency was varied from 10–300 Hz was applied to the set-up and results compared with that of no vibration. Samples were taken at different times during the solidification process and compared with respect to solid material present.

Eexperimental Investigation of Heat Characteristics of Liquid Flow With Micro-Encapsulated Phase Change Material

2008 ◽  
Author(s):  
Rami Sabbah ◽  
Jamal Yagoobi ◽  
Said Al Hallaj
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Wall Temperature ◽  
Tube Wall ◽  
Operating Conditions ◽  
Working Fluid ◽  
Tube Wall Temperature ◽  
Encapsulated Phase Change Material ◽  
Change Material

This experimental study investigates the effect of presence of Micro-Encapsulated Phase Change Material (MEPCM) within the working fluid on thermal performances of the cooling system. To conduct this study, an experimental setup consisting of a steel tube with an inner diameter of 4.3mm, outer diameter of 6.3mm and a length of 1,016mm is selected. 5%, 10% and 20% mass concentration MEPCM slurries with particle diameter ranging between 5–15μm were included in this study. Tube wall temperature profile, fluid inlet, outlet temperatures, the pressure drop across the tube are measured and corresponding heat transfer coefficients are determined for various operating conditions. Differential Scanning Calometery (DSC) test results for an iterative method for local variables calculation. The experimental results showed significant enhancement in heat transfer coefficient higher than 50% and reduction in tube wall temperature higher than 35%. The controlling parameters are identified and their effects on the heat transfer characteristics are evaluated and analyzed.

scholarly journals CFD and Experimental Analysis of Phase Change Material Behaviour Encapsulated in Internally Finned Spherical Capsule

2019 ◽  
Vol 128 ◽  
pp. 01002
Author(s):  
G. Kumaresan ◽  
R. Santosh ◽  
H. Revanth ◽  
G. Raju ◽  
S. Bhattacharyya
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Computational Study ◽  
Solidification Process ◽  
Transition Process ◽  
Spherical Capsule ◽  
Change Material

Phase change material (PCM) based Thermal Energy Storage (TES) system is a proven technology to store/release a large amount of energy as latent heat during the phase transition process. In spite of the advantages, a major weakness with PCMs is their low thermal conductivity in both solid and liquid phases which seriously affects the heat transfer rate. Over the past two decades various efforts have taken place to enhance the heat transfer rate during the melting/solidification process of phase change material (PCM) encapsulated in various shape of containers. However, very few attempts have been made on accounting the heat transfer augmentation in internally finned spherical capsule. In the present study, CFD analysis is carried out to explore and report the effect of fin orientation on heat transfer enhancement of a paraffin PCM filled in an internally finned spherical capsule. Keeping the same surface area of fin but oriented differently (orthogonal and circumferential) in spherical capsule is undertaken for the computational analysis. In addition, spherical capsule with no fin configuration is alsoconsidered in the present analysis to compare with finned configuration results. The CFD results showed that the orthogonally finned spherical capsule resulted in appreciable reduction in total time takenfor complete melting/solidification process than the circumferential fin and no fin configuration. Thesame computational study is performed experimentally in order to validate the CFD results.

Heat Transfer in Laminar Flow With a Phase Change Boundary

1982 ◽  
Vol 104 (4) ◽  
pp. 678-682 ◽  
Author(s):  
S. Asgarpour ◽  
Y. Bayazitoglu
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Water System ◽  
Heat Transfer Fluid ◽  
Bulk Temperature ◽  
Solidification Temperature ◽  
Interface Position ◽  
Tube Heat Exchanger ◽  
Change Material

Thermal analysis of a shell-and-tube heat exchanger with a phase change material (PCM) on the shell side and a heat transfer fluid flowing through the tube is presented. The phase change material was initially liquid at its solidification temperature. The heat transfer fluid originates from an isothermal reservoir at a temperature which is lower than the temperature of the phase change material. Numerical results of finite difference method are obtained with a ratio of the thermal properties of the phase change material to the fluid to represent n-octadecane, wax-water system. Variations of the temperature distribution for the fluid, and the PCM, and the interface position of the phase change material in the radial and axial directions are presented. The bulk temperature of the fluid is shown to be a function of the Stefan number, the Fourier number and the velocity profile. It is also shown that the Biot number varies in the axial direction and the heat capacity effects of the phase change material, even at low Stefan numbers are significant.

scholarly journals A numerical model and validation of phase change material integrated thermoelectric radiant cooling panel

2019 ◽  
Vol 111 ◽  
pp. 01001
Author(s):  
Hansol Lim ◽  
Hye-Jin Cho ◽  
Seong-Yong Cheon ◽  
Soo-Jin Lee ◽  
Jae-Weon Jeong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Numerical Model ◽  
Surface Temperature ◽  
Phase Change ◽  
Transfer Coefficient ◽  
Phase Change Material ◽  
Overall Heat Transfer Coefficient ◽  
Radiant Cooling ◽  
Change Material

A phase change material based radiant cooling panel with thermoelectric module (PCM-TERCP) is proposed in this study. It consists of two aluminium panels, and phase change materials (PCMs) sandwiched between the two panels. Thermoelectric modules (TEMs) are attached to one of the aluminium panels, and heat sinks are attached to the top side of TEMs. PCM-TERCP is a thermal energy storage concept equipment, in which TEMs freeze the PCM during the night whose melting temperature is 16○C. Therefore, the radiant cooling panel can maintain a surface temperature of 16◦C without the operation of TEM during the day. Furthermore, it is necessary to design the PCM-TERCP in a way that it can maintain the panel surface temperature during the targeted operating time. Therefore, the numerical model was developed using finite difference method to evaluate the thermal behaviour of PCM-TERCP. Experiments were also conducted to validate the performance of the developed model. Using the developed model, the possible operation time was investigated to determine the overall heat transfer coefficient required between radiant cooling panel and TEM. Consequently, the results showed that a overall heat transfer coefficient of 394 W/m2K is required to maintain the surface temperature between 16○C to 18○C for a 3 hours operation.

Experimental Study on Thermal Characteristics of Finned Coil LHSU Using Paraffin as Phase Change Material

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Guansheng Chen ◽  
Nanshuo Li ◽  
Huanhuan Xiang ◽  
Fan Li
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Phase Change ◽  
Phase Change Material ◽  
Water Flow ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage ◽  
Change Material

It is well known that attaching fins on the tubes surfaces can enhance the heat transfer into and out from the phase change materials (PCMs). This paper presents the results of an experimental study on the thermal characteristics of finned coil latent heat storage unit (LHSU) using paraffin as the phase change material (PCM). The paraffin LHSU is a rectangular cube consists of continuous horizontal multibended tubes attached vertical fins at the pitches of 2.5, 5.0, and 7.5 mm that creates the heat transfer surface. The shell side along with the space around the tubes and fins is filled with the material RT54 allocated to store energy of water, which flows inside the tubes as heat transfer fluid (HTF). The measurement is carried out under four different water flow rates: 1.01, 1.30, 1.50, and 1.70 L/min in the charging and discharging process, respectively. The temperature of paraffin and water, charging and discharging wattage, and heat transfer coefficient are plotted in relation to the working time and water flow rate.

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