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## Investigation of the influence of diamond powder on thermal properties of phase change materials

### Wojciech Godlewski

#### Abstract

This diploma thesis work entitled "Investigating the impact of diamond powder on the thermal properties of phase change materials" was created to investigate the effect of diamond powder on the thermal properties of phase change materials on the example of octadecane. The experiment involved mixing of diamond powder with a specific granulation with the aforementioned representative of the alkanes group. Three different grain sizes were used: 50, 150 and 250 micrometres. The improvement of thermal diffusivity and thermal conductivity in newly formed mixtures were compared to the pure forms of the phase-change materials used. Initial mixing showed strong stratification for each granulation due to the low viscosity of the mixture and too large differences between component densities. It was decided to add amorphous silicon dioxide to the mixtures, which increases density of the mixture. The optimal percentage of silica was estimated experimentally. Two mixing methods have been tested: the use of an ultrasonic device and manual mixing with a glass rod. Due to the fact that the Authors had a very limited amount of diamond powder at their disposal, the volume of mixtures was very small. Thus, the use of an ultrasonic homogenizer was very troublesome, and additionally led to an increase in the temperature of the mixture during the operation of the program. Therefore, the manual method was chosen. Measurements of thermal parameters were carried out using DSC and LFA technologies. Thermal diffusivity as well as specific heat, latent heat and thermal conductivity were obtained from the measurements. At the beginning, the influence of amorphous silica itself on the thermal properties of the tested materials in a mixture with this compound was examined. A very small change in thermal parameters was observed. The influence of different heating speeds on the specific heat of the substance and latent heat of the phase transformation was also examined and on the selected examples the degree of supercooling of the substance was analysed. Then the results were compared and conclusions were drawn. Thermal conductivity and diffusivity increased significantly. The improvement in the case of the largest granulation was over two times for thermal diffusivity and over three and a half times for thermal conductivity. For smaller percentages of diamond powder thermal conductivity increased approximately from 2 to 2.8 times, and thermal diffusivity from 1.5 to 1.6 times. An important observation was that the mixture with higher granulation of diamond powder had greater tendency for sedimentation. The results of the tests of specific heat and latent phase transition heat showed that with the increasing content of diamond, the specific heat of the mixture decreases almost twice, and the latent heat can decrease by up to three times. The effect of diamond powder on reducing the degree of supercooling of the mixture was also observed.
Diploma type
Engineer's / Bachelor of Science
Diploma type
Engineer's thesis
Author
Wojciech Godlewski (FPAE) Wojciech Godlewski,, Faculty of Power and Aeronautical Engineering (FPAE)
Title in Polish
Badanie wpływu proszku diamentowego na właściwości cieplne materiałów zmiennofazowych
Supervisor
Roman Domański (FPAE/IHE) Roman Domański,, The Institute of Heat Engineering (FPAE/IHE)Faculty of Power and Aeronautical Engineering (FPAE)
Certifying unit
Faculty of Power and Aeronautical Engineering (FPAE)
Affiliation unit
The Institute of Heat Engineering (FPAE/IHE)
Study subject / specialization
, Energetyka (Power Engineering)
Language
(en) English
Status
Finished
Defense Date
11-02-2019
Issue date (year)
2019
Reviewers
Tomasz Wiśniewski (FPAE/IHE) Tomasz Wiśniewski,, The Institute of Heat Engineering (FPAE/IHE)Faculty of Power and Aeronautical Engineering (FPAE) Roman Domański (FPAE/IHE) Roman Domański,, The Institute of Heat Engineering (FPAE/IHE)Faculty of Power and Aeronautical Engineering (FPAE)
Keywords in Polish
materiały zmiennofazowe, dyfuzyjność cieplna, przewodność cieplna, ciepło utajone, LFA, DSC, prędkość ogrzewania, przechładzanie, ciepło właściwe, PCM
Keywords in English
phase change materials, thermal diffusivity, thermal conductivity, latent heat, LFA, DSC, heating rate, supercooling, specific heat, PCM
Abstract in Polish
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Identyfikator pracy APD: 31333

Uniform Resource Identifier
https://repo.pw.edu.pl/info/bachelor/WUT1c7f8f426f934fb284fe4e3a57905f2e/
URN
urn:pw-repo:WUT1c7f8f426f934fb284fe4e3a57905f2e

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