Thermal coupling-decoupling mechanism of heat transfer across van der Waals interfaces in n-eicosane

Abstract In the present work the dynamics of a non-isothermal thin viscous film, with fully mobile interfaces, is studied in the case when the inertial, viscous, capillary, van der Waals and thermocapillary forces are important. The film is laterally bounded by a frame, whose temperature is higher than the environmental one. The stability of the static film shapes is examined numerically by a linear and non-linear analysis. The results show that the film rupture is mostly governed by the dynamics, but it could be delayed or enhanced by the thermocapillary convection and the heat transfer with the surrounding environment.

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VAN DER WAALS FRICTION: A HAMILTONIAN TEST-BED

International Journal of Modern Physics A ◽

10.1142/s0217751x12600020 ◽

2012 ◽

Vol 27 (15) ◽

pp. 1260002 ◽

Cited By ~ 3

Author(s):

GABRIEL BARTON

Keyword(s):

Heat Transfer ◽

Quantum Mechanics ◽

Temperature Dependence ◽

Low Temperatures ◽

Van Der Waals ◽

Relative Speed ◽

Casimir Forces ◽

Test Bed ◽

The Status ◽

Two Bodies

In the van der Waals regime (neglecting relativity and retardation), we find the power P generated by friction between two Drude-modelled dissipative half-spaces, at fixed separation and relative speed u, admitting only low u and low temperatures. This requires only elementary quantum mechanics; but the results can serve as partial checks on calculations in the fully retarded Casimir regime. They also raise questions regarding (i) the frequency-distribution of P; (ii) the status of predictions about Casimir forces generally, insofar as they feature parameters like conductivities with their empirical temperature-dependence; and (iii) calculations of heat transfer, insofar as they assume fluctuations in the two bodies to be uncorrelated.

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The Application of Building Physics in the Design of Roof Windows

Energies ◽

10.3390/en12122300 ◽

2019 ◽

Vol 12 (12) ◽

pp. 2300 ◽

Cited By ~ 4

Author(s):

Jan Tywoniak ◽

Vítězslav Calta ◽

Kamil Staněk ◽

Jiří Novák ◽

Lenka Maierová

Keyword(s):

Heat Transfer ◽

Building Envelope ◽

Surface Heat ◽

Thermal Coupling ◽

Passive House ◽

Thermal Transmittance ◽

Temperature Requirements ◽

Parametric Studies ◽

Building Physics ◽

Further Development

This paper deals with a small but important component in a building envelope, namely roof windows in pitched roofs. Building physics methods were used to support the search for new solutions which correspond to the maximum extent for requirements for passive house level design. The first part of the paper summarizes the key phenomena of heat transfer, mainly based on a comparison of vertical windows in walls. The results of repeated two-dimensional heat transfer calculations in the form of parametric studies are presented in order to express the most important factors influencing thermal transmittance and minimum surface temperatures. Several configuration variants suitable for technical design are discussed. It was found that a combination of wood and hardened plastics in the window frame and sash is the preferred solution. The resulting thermal transmittance can be up to twice as low as usual (from 0.7 down to 0.5 W/(m2·K), with further development ongoing. Surface temperature requirements to avoid the risk of condensation can be safely fulfilled. Concurrently, it is shown that the relative influence of thermal coupling between the window and roof construction increases with the improvement of window quality. Specific attention was given to the effect of the slanting of the side lining, which was analyzed by simulation and measurement in a daylight laboratory. The increase in thermal coupling due to slanting was found to be negligible. Motivations for specific building physics research are mentioned, such as the need to study the surface heat transfer in the case of inclined windows placed in a deep lining.

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