Temat: Diffusivity - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Analysis of metrological conditioning of thermal diffusivity measurements applying modified Angstroms method at scanning mode operation
Autorzy:: Panas, A. J.
Nowakowski, M.
Powiązania:: https://bibliotekanauki.pl/articles/242228.pdf
Data publikacji:: 2011
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: thermal diffusivity
thermophysical properties
temperature oscillation
modified Angstrom technique
Opis:: A technique of the temperature dependent thermal diffusivity investigation has been analysed. The technique is based on the modified Angstrom method utilising periodic temperature oscillations in a slab specimen. The additional modification consists of imposing linear temperature changes - application of linear scans. This scanning mode procedure enables investigation of the thermal diffusivity over a certain temperature interval. The thermal diffusivity is calculated independently from two relations based on the measured amplitude attenuation and the measured phase shift of the temperature oscillation passing through the investigated specimen. The paper discuses the problem of the thermal diffusivity identification uncertainty. As a result correction factors for the thermal diffusivity data derived from simplified formulae have been determined. The procedure of the thermal diffusivity measurement has been verified by numerical modelling. Comparison between the initial and response signals with illustration of the linear scan imposed to a basic oscillation with reference to a classical procedure of subsequent steps, illustration of the approximation error analysis methodology and results in the form of a thermal diffusivity correction factor, comparison between the uncorrected and corrected applying in numerical modelling of the temperature oscillation experiment are presented in the paper.
Źródło:: Journal of KONES; 2011, 18, 2; 339-347
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Investigation of thermal properties of novel phase change material mixtures (octadecane-diamond) with laser flash analysis
Autorzy:: Sierakowski, Mateusz
Godlewski, Wojciech
Domański, Roman
Kapuściński, Jakub
Wiśniewski, Tomasz
Kubiś, Michał
Powiązania:: https://bibliotekanauki.pl/articles/246255.pdf
Data publikacji:: 2019
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: phase change materials
PCM
diamond powder
thermal conductivity
thermal diffusivity
Opis:: Phase change materials (PCMs) are widely used in numerous engineering fields because of their good heat storage properties and high latent heat of fusion. However, a big group of them has low thermal conductivity and diffusivity, which poses a problem when it comes to effective and relatively fast heat transfer and accumulation. Therefore, their use is limited to systems that do not need to be heated or cooled rapidly. That is why they are used as thermal energy storage systems in both large scale in power plants and smaller scale in residential facilities. Although, if PCMs are meant to play an important role in electronics cooling, heat dissipation, or temperature stabilization in places where the access to cooling water is limited, such as electric automotive industry or hybrid aviation, a number of modifications and improvements needs to be introduced. Investigation whether additional materials of better thermal properties will affect the thermal properties of PCM is therefore of a big interest. An example of such material is diamond powder, which is a popular additive used in abradants. Its thermal diffusivity and conductivity is significantly higher than for a pure PCM. The article presents the results of an analysis of the effect of diamond powder on thermal conductivity and diffusivity of phase change materials in the case of octadecane.
Źródło:: Journal of KONES; 2019, 26, 4; 211-218
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Investigation of the effect of diamond powder on the thermal properties of octadecane using differential scanning calorimetry
Autorzy:: Godlewski, Wojciech
Sierakowski, Mateusz
Domański, Roman
Kapuściński, Jakub
Powiązania:: https://bibliotekanauki.pl/articles/242378.pdf
Data publikacji:: 2019
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: phase change materials
PCM
diamond powder
thermal conductivity
thermal diffusivity
Opis:: The purpose of this work was to examine 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. Two different grain sizes were used: 50 and 250 micrometres. The change of specific heat, latent heat of phase change and degree of supercoiling in newly formed mixtures was compared to the pure forms of the phase-change materials used. Initial mixing with a glass-stirring rod 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 amorphous silicon dioxide was estimated experimentally. Measurements of thermal parameters were carried out using DSC technology. 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 supercoiling of the mixture was also observed. An important observation was that the mixture with higher granulation of diamond powder had greater tendency for sedimentation. This method could be used to increase thermal conductivity and diffusivity of phase change materials and make them viable for use in systems that require cooling at high rate or temperature stabilization, such as control systems in electronic vehicles or aviation industry and at the same time decrease the degree of supercoiling which could increase the efficiency of system.
Źródło:: Journal of KONES; 2019, 26, 3; 39-45
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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