An experimental investigation of microchannel flow with internal pressure measurements

Experimental Analysis of Pressure Drop and Laminar to Turbulent Transition for Gas Flows in Smooth Microtubes

“…This rule has been confirmed numerically by Guo and Wu [28]. Recently, Kohl et al [19], Asako et al [29] and Li et al [30] have obtained numerical and experimental results on the frictional characteristics of compressible flows through straight microchannels having a rectangular and circular cross-section, respectively. Li et al [30] and Asako et al [29] performed computational investigations on the effect of the compressibility for a wide range of Reynolds numbers and Mach numbers.…”

“…8-9 2007 The dependence of the Poiseuille number on the Mach number in the laminar regime can explain the deviation from the Poiseuille law of some experimental results especially for short tubes, where the average values of Ma reached in the experimental test were larger (shorter microtubes), as evidenced by Figure 7. Another conclusion that can be drawn from Figure 7 is that in order to evidence the effect of the average Mach number, careful experiments must be designed; in fact, a value of the un- Trapezoid 100-720 1000-3000 Acosta et al [32] Rectangle -2770 Choi et al [33] Circle 640-8100 500-2000 Yu et al [34] Circle -1700-6000 Stanley [24] Rectangle -1500-2000 Li et al [13] Circle 145-715 2300 Li et al [35] Circle 145-715 1700-2000 Yang et al [14] Circle 690-3984 1200-3800 Li et al [36] Circle 690-3984 1700-1900 Tang and He [20] Rectangle/circle 498-995 1900-2500 Faghri and Turner [37] Rectangle/trapeziod 263-5717 2000-2500 Kohl et al [19] Rectangle 220-533 2300-6000 certainty on f Re equal to 10% is sufficient to mask its influence up to Ma equal to 0.2.…”

“…They concluded that the quantitative behavior is satisfactorily predicted-within the experimental uncertainty, which amounted to a maximum of ±20%-by the incompressible theory, and that the frictional losses at the inlet and outlet only give a minor contribution to the total pressure drop. Kohl et al [19] studied the flow of water and air in rectangular silicon microchannels with a hydraulic diameter varying between 24.9 and 99.8 µm using internal pressure measurements and could predict their data quite well in the case of laminar flow employing the classical correlations. Tang and He [20] measured friction factors in fused silica microtubes and square microchannels with diameters ranging from 50 to 201 µm.…”

Experimental investigation of fluid flow and heat transfer in a single-phase liquid flow micro-heat exchanger

“…The experimental results are compared with the analytical apparent friction factor (Eq. (4)) which includes the friction factor of the fully developed flow (f fd ) and the pressure defect or Hagenbach factor, K(x) [23], evaluated in the entire length of the square cross section micro channels, as stated by Steinke and Kandlikar [24] and Kohl et al [7].…”

“…Another possible explanation is the influence of the entrance re gion, because most of the works consider the flow to be fully devel oped. Moreover, as Steinke and Kandlikar [6] and Kohl et al [7] show, the inlet and outlet effects should be carefully considered for a proper statement of the pressure drop along the channels. In recent investigations, Chakraborty and co workers [8 10], focus on the surface characteristics of microchannels and model the complex mechanisms by which roughness and hydrophobic effects might alter the fluid flow parameters as compared to classical theory.…”