Constant - Wall - Temperature Nusselt Number in Micro and Nano - Channels  

Oleh:

Hadjiconstantinou, Nicolas G. ; Simek, Olga

Jenis: Article from Bulletin/Magazine
Dalam koleksi: Journal of Heat Transfer vol. 124 no. 2 (Apr. 2002), page 356-364.
Topik: temperature; heat transfer; microscale; molecular dynamics; monte carlo; nanoscale

Ketersediaan

Perpustakaan Pusat (Semanggi) Nomor Panggil: JJ90.3 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

We investigate the constant - wall - temperature convective heat - transfer characteristics of a model gaseous flow in two - dimensional micro and nano - channels under hydrohynamicaly and thermally fully developed conditions. Our investigation covers both the slip - flow regime o <= Kn <= 0 .1 , and most of the transition regime 0.1 < Kn <= 10, where Kn, the knudsen number, is defined as the ratio between the molecular mean free path and the channel height. We use slip - floe theory in the presence of axial heat conduction to calculate the nusselt number in the range 0 <= Kn <= 0.2, and a stochastic molecular simulation technique known as the direct simulation monte carlo (DSMC) to calculate the nusselt number in the range 0.02 < Kn < 2. Inclusion of the effects of axial heat conduction in the continuum model is necessary since small - scale internal flows are typically characterized by finite peclet numbers. Our results show that the slip - floe prediction is in good agreement with the DSC results for Kn <= 0.1, but also remains a good approximation beyond its expected range of applicability. We also show that the nusselt number decreases monotomically with increasing knudsen number in the fully accomodating case, both in the slip - flow and transition regimes. In the slip - flow regime, axial heat conduction is found to increase the nusselt number, this effect is largest at Kn = 0 and is of the order of 10 percent. Qualitatively similar results are obtained for slip- flow heat transfer in circular tubes.

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