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.

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.

Enhancement of heat transfer in paraffin wax PCM using nano graphene composite for industrial helmets

2019 ◽  
Vol 26 ◽  
pp. 100982 ◽  
Author(s):  
Mohamed Ashiq Ali ◽  
Fayaz ◽  
Rohit Francisco Viegas ◽  
M B Shyam Kumar ◽  
Rajendra Kumar Kannapiran ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Paraffin Wax ◽  
Enhancement Of Heat Transfer ◽  
Graphene Composite ◽  
Nano Graphene

Study on Natural Convection From a Buried Pipe With Backfill

2007 ◽  
Author(s):  
C. C. Ngo ◽  
F. C. Lai
Keyword(s):  
Heat Transfer ◽  
Flow Fields ◽  
Step Change ◽  
Buried Pipe ◽  
Numerical Work ◽  
Thermal Buoyancy ◽  
Visualization Experiment ◽  
Actual Flow ◽  
Set Up ◽  
Good Agreement

Heat transfer and fluid flow induced by thermal buoyancy from a buried pipe with backfill has been examined in this study. Hele-Shaw cells with different gap widths were constructed to simulate a porous medium with distinct permeablities. The flow visualization experiment was set up to investigate how a step change in the permeability of a backfill would affect the flow patterns from a heated pipe. Both permeable and impermeable top surfaces with different buoyancy strengths were considered in this experiment. Using time-elapsed photographs, one observes that the flow fields for permeable and impermeable top boundaries displayed distinct characteristics. The presence of recirculating cell in the more permeable layer was confirmed. The flow fields predicted by numerical work are in good agreement with those observed in the experiment. Thus it is expected that the actual flow field would closely resemble those reported in the present study.

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.

Study of PCM-Based Pin-Fin Heat Sinks

2009 ◽  
Author(s):  
V. Dubovsky ◽  
G. Barzilay ◽  
G. Granot ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Material Properties ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Base Temperature ◽  
Pin Fin ◽  
Dependent Parameter ◽  
Set Up ◽  
Change Material

This study deals with heat transfer from pin-fin aluminum heat sinks to a phase-change material (PCM) which fills the inter-fin space. The sinks have a horizontal base and accordingly their fins are vertical. The sink base dimensions are 100 mm by 100 mm, with fin height of 10 mm, 20 mm or 30 mm, and cross section of 4 mm×4 mm. The number of fins varies, e.g. 49, 64, 81, etc. The applied power is between 50 W to 250 W, corresponding to the heat fluxes of 5–25 kW/m2. The present paper reports mostly numerical results, but the numerical model is validated using the findings from an ongoing experimental investigation, in which a commercially available paraffin wax RT-35 is used as the PCM, with the melting temperature of about 35 °C. The simulations reflect the material properties, geometry, and other features of the experimental set-up, including heating with an electrical foil heater. Accordingly, the base temperature serves as the dependent parameter. Numerical simulations, performed using the Fluent 6.2 software, serve to obtain detailed melting patterns and explain the effect of fin size and number on sink performance.

scholarly journals PENGGUNAAN PARAFFIN WAX SEBAGAI PENYIMPAN KALOR PADA PEMANAS AIR TENAGA MATAHARI THERMOSYPHON

ROTASI ◽  
2016 ◽  
Vol 18 (3) ◽  
pp. 76 ◽  
Author(s):  
Muhammad Nadjib
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Paraffin Wax ◽  
Heat Transfer Fluid ◽  
Sensible Heat ◽  
Latent Heat Storage ◽  
Change Material

Pemanas Air Tenaga Matahari (PATM) konvensional umumnya menggunakan air sebagai penyimpan energi termal. Pemakaian sensible heat storage (SHS) ini memiliki kekurangan, diantaranya adalah densitas energinya rendah. Di sisi lain, latent heat storage (LHS) mempunyai sifat khas yaitu densitas energinya tinggi karena melibatkan perubahan fasa dalam penyerapan atau pelepasan kalor. Material LHS sering disebut phase change material (PCM). Penggunaan PCM pada PATM menarik dilakukan untuk meningkatkan densitas energi sistem. Penelitian ini bertujuan untuk menyelidiki perilaku termal penggunaan paraffin wax di dalam tangki PATM jenis thermosyphon. Penelitian menggunakan kolektor matahari pelat datar dan tangki thermal energy storage (TES) yang dipasang secara horisontal di sisi atas kolektor. Di dalam tangki terdapat alat penukar kalor yang terdiri dari sekumpulan pipa kapsul dimana di dalamnya berisi paraffin wax. Air digunakan sebagai SHS dan heat transfer fluid (HTF). Termokopel dipasang di sisi HTF dan sisi PCM. Piranometer dan sensor temperatur udara luar diletakkan di dekat kolektor matahari. Pengambilan data dilakukan selama proses charging. Temperatur HTF, PCM dan intensitas radiasi matahari direkam setiap 30 detik. Data ini digunakan untuk mengetahui evolusi temperatur HTF dan PCM. Berdasarkan evolusi temperatur ini kemudian dianalisis perilaku termal PATM. Hasil dari penelitian ini adalah bahwa paraffin wax telah berfungsi sebagai penyimpan energi termal bersama air di dalam tangki PATM jenis thermosyphon. PCM memberi kontribusi yang cukup signifikan terhadap kapasitas penyimpanan energi sistem. Efisiensi kolektor lebih optimal karena PCM dapat mempertahankan stratifikasi termal sampai akhir charging. Adanya PCM mampu mengendalikan penurunan efisiensi pengumpulan energi saat intensitas radiasi matahari menurun. Alat penukar kalor yang digunakan cukup efektif yang ditandai dengan kecepatan pemanasan rata-rata antara HTF dan PCM yang tidak berbeda jauh.

scholarly journals Experimental study of solidification of paraffin wax in solar based triple concentric tube thermal energy storage system

2018 ◽  
Vol 22 (2) ◽  
pp. 973-978 ◽  
Author(s):  
Rengarajan Ravi ◽  
Karunakaran Rajasekaran
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Solidification Process ◽  
Energy Storage System ◽  
Paraffin Wax ◽  
Heat Transfer Fluid ◽  
Thermal Energy Storage System

This paper addresses an experimental investigation of a solar based thermal energy storage system to meet current energy demand especially for milk industry in Tamil Nadu, India. A solar based energy storage system has been designed to study the heat transfer characteristics of paraffin wax where it is filled in the middle tube, with cold heat transfer fluid flowing outer tube, inner tube, and both tubes at a time during solidification process in a horizontal triple concentric heat exchanger. In this study, main concentrations are temperature distributions in the energy storage materials such as paraffin wax during solidification process and total solidification time. Three heat recovery methods were used to solidify paraffin wax from the inside tube, outside tube, and both tubes methods to improve the heat transfer between heat transfer fluid and phase change materials. The experiment has been performed for different heat transfer fluid mass-flow rates and different inlet temperatures and predicted results shows that solidification time is reduced.

scholarly journals Numerical analysis of the solidification process of water used as PCM in a rectangular latent heat thermal storage unit

2021 ◽  
Vol 2116 (1) ◽  
pp. 012044
Author(s):  
M A Dekhil ◽  
J V Simo Tala ◽  
O Bulliard-Sauret ◽  
D Bougeard
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Latent Heat ◽  
Temporal Evolution ◽  
Solidification Process ◽  
Thermal Storage ◽  
Storage Unit ◽  
Average Temperature ◽  
Flow And Heat Transfer ◽  
Change Material

Abstract A numerical analysis of the solidification process of water used as phase change material (PCM) has been carried out in a rectangular latent heat thermal storage unit. The major heat transfer phenomena involved in such a process were numerically characterized using the CFD code Star CCM+. During the solidification process, the flow and heat transfer were analysed through vector field, temperature and solid fractions contours. Quantitative global results such as the temporal evolution of the average temperature of the PCM were also provided during the solidification process. The present study shows that the natural convection plays an important role in heat transfer kinetics during solidification process.

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.

Sign in / Sign up

Export Citation Format

Share Document