Semiempirical correlation for the friction factor of gas flowing through smooth microtubes

Abstract

This article focuses on determining the friction factor from experimental results available in literature for gas flow in a smooth tube. The friction factor (f), Reynolds number (Re), and Knudsen number (Kn) are calculated from the reported pressure drop and mass flow rate. The variation in friction factor with Knudsen number and Reynolds number is analyzed in the Kn range of 0.0004–2.77 and Re range of 0.001–227. It is found that f Re is independent of gas and surface material and can be estimated by a simple semiempirical correlation within ±20% and a mean absolute error of 8%. The correlation gives friction factor for a particular value of Knudsen number and Reynolds number, irrespective of the type of gas or surface material.

Experimental measurement on tangential momentum accommodation coefficient in a single microtube

“…However, the flow in a tube is a two-dimensional problem, which is much simpler than that in a rectangular channel or a bundle of tubes where the problem could be a three-dimensional problem. It is also worth noting that the reported TMACs are still few (Agrawal and Prabhu 2008;Verma et al 2009) compared to EAC (Saxena and Joshi 1988), which is known to have a certain amount of variation among data in many cases. Therefore, the measurement of TMAC itself is important and valuable.…”

Low Mach number slip flow through diverging microchannel

“…The experimental fRe value is compared against the fRe value obtained from the correlation of Verma et al [8] fRe…”

“…It is important to understand the gas flow behavior through such geometry in terms of pressure drop, velocity distribution and flow structure. Most of the earlier work however focused on uniform cross-section microchannels with liquid or gas flow [1][2][3][4][5][6][7][8][9][10][11][12] and flow through other cross-section area microchannels have been inadequately studied. The low pressure gas flows through conventional tubes are governed by the same set of non-dimensional parameters as that of gas microflow; Sreekanth [13] and Demsis et al [14,15].…”

Heat transfer coefficient of gas flowing in a circular tube under rarefied condition

“…The friction factor is calculated using the definition given by Wu and Little [22]. The friction factor (f) times Reynolds number as a function of Knudsen number matches with the earlier results of Sreekanth [21] and other researchers [23,20]. The set up is also validated for heat transfer coefficient in the continuum regime.…”