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Numerical analysis of the transient and non-isothermal channel flow of a third-grade fluid with convective cooling

Chinyoka Tiri, Makinde Oluwole Daniel

Engineering Transactions

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2020

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Vol. 68, iss. 4

335--351

EN

We investigate the unsteady, non-isothermal, pressure driven channel flow of a third grade liquid subject to exothermic reactions. We assume temperature dependent fluid viscosity and also that the flow is subjected to convective cooling at the channel walls. The exothermic reactions are modelled via Arrhenius kinetics and the convective heat exchange with the ambient at the channel walls follows Newton’s law of cooling. The time-dependent, coupled, and nonlinear partial differential equations governing the flow and heat transfer problem are solved numerically using efficient, semi-implicit finite difference algorithms. The sensitivity of the fluid flow and heat transfer system to the various embedded parameters is explored.

2

Aspekt termiczny wykorzystania modułów fotowoltaicznych w architekturze

Marchwiński J.

Materiały Budowlane

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2013

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nr 6

68--71

EN

Photovoltaic (PV) modules are devices that transform solar energy into electric energy. This is their primary purpose. With the aid of the other photovoltaic system elements, the PV modules or different configurations of PV cells enable to provide the building with electric current. Thermal aspect is a less known side of the PV modules use. Because of their basic function, it is being avoided or unappreciated, while thermal energy accompanies photovoltaic conversion every time, as its side effect. The article discusses the ways the thermal energy may be used in buildings with photovoltaic systems. Also, PV dules, application as solar protection elements preventing buildings overheating is included in the thermal aspect. It has been proved that architecturally integrated PV modules may positively contribute to the creation of themal environment of the building, both in terms of their passive heating and cooling. At the same time, they may exert a positive effect on architectural features and energetic behaviour of the building as well as the PV modules efficiency.

3

Convective Cooling of a Disc Brake During Single Braking

Adamowicz A., Grześ P.

Acta Mechanica et Automatica

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2012

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Vol. 6, no. 2

5-10

EN

This study is primarily focused on the investigation of an impact of heat transfer coefficient on heat dissipation from the solid disc using the finite element method (FEM). The analysis was carried out within four individual cases of braking of the passenger vehicle simulating mountain descent with different velocities and the following release periods, where the convective terms of cooling were dependent on the angular velocity of the disc. For the purpose of confronting contrasting conditions of the braking action, apart from heating region, the whole surface of the disc was insulated. The process was performed under the operation conditions of a real front disc brake, whose dimensions and thermophysical properties of materials were adopted and applied to the FE model. It was concluded that the influence of cooling of the exposed surfaces of the disc during relatively short braking is insignificant. However the period after brake release results in considerable decrease in temperature of the disc.

4

Transient analysis of alloy freezing in finite media with energy generation and convective cooling

Kumar S., Katiyar V. K.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no 4

1155-1168

EN

The effects of volumetric energy generation on phase change problems are important for many engineering applications including casting of nuclear waste materials, vivo freezing of biological tissues solar collectors etc. In the present study, a 1-D transient heat transfer analysis is carried out to study the effect of volumetric heat generation on alloy solidification in finite media with convective cooling. Enthalpy method is used to solve the mathematical model. The temperature profile and the motion of freezing interface are calculated for different values of volumetric heat generation and convective cooling. It is found that the motion of freezing interface slows down with an increase in the heat generation rate and for large values of heat generation it is not possible to solidify the whole region. The freezing accelerates with respect to an increasing rate of convective cooling. Further, for large values of heat generation the whole region can solidify by increasing convective cooling.

5

Zastosowanie tunelu powietrznego do badań konwekcyjnego odprowadzania ciepła z układów elektronicznych

Felczak M., Ostrowski B., Więcek B.

Elektronika : prace naukowe

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2004

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nr 9

107-124

PL

W artykule przedstawiono projekt tunelu powietrznego do badań chłodzenia konwekcyjnego układów elektronicznych. Projekt został zweryfikowany poprzez symulacje numeryczne wykonane za pomocą programu FLUENT. W dalszej części pracy przedstawiono metodą laserowego noża świetlnego. Wykorzystuje sieją do pomiaru prędkości przepływu powietrza w tunelu, który to pomiar jest niezbędny do wyznaczenia warunków chłodzenia. W ostatniej części pracy przedstawiony jest przykład zastosowania tunelu do badań odprowadzania ciepła w elektronice. Opisano i zbadano efekt śladu termicznego podczas chłodzenia konwekcyjnego układów elektronicznych.

EN

The article presents design of a low-speed wind tunnel for forced convective cooling investigations of electronic devices. Design method of the tunel is presented. Results are verified by numerical simulations completed with the Fluent software. Particle image velocimetry method (PIV) as one of the method proposed for air velocity measurements is presented. Velocity measurements during wind tunnel investigations are necessary to know electronic devices cooling conditions. In the last section of the article, an example of electronic cooling investigations for the designed wind tunnel, is presented. It illustates the importance of thermal wake effect during heat dissipation in electronics.