FRICTION AND CONVECTION STUDIES OF R-134a IN MICROCHANNELS WITHIN THE TRANSITION AND TURBULENT FLOW REGIMES

Single-phase convective heat transfer in microchannels: a review of experimental results

“…Hegab et al [68] studied experimentally the fluid flow and the heat transfer of R134a in rectangular microchannels micromilled in aluminium with hydraulic diameters ranging from 112 to 210 µm and for an aspect ratio from 1 to 0.667. The few data collected in the laminar regime were very close to the predictions using the classical laminar flow theory.…”

Experimental study of compressibility, roughness and rarefaction influences on microchannel flow

“…First, nitrogen and helium flows in fused silica microtubes (D = 50-201 lm), square microchannels (D h = 52-100 lm) and stainless steel microtubes (D = 119-300 lm) are measured to verify the roughness effect. Second, nitrogen and helium flow in fused NA Urbanek et al [4] NA Peng et al [5] NA Mala and Li [6] 0.69-3.5 Papautsky et al [7] NA Qu et al [8] 1.76-2.85 Jiang et al [9] 1.9-12.1 Celata et al [10] 2.65 Brutin and Tadrist [11] <0.02 Acosta et al [ [19] NA Heun [20] NA Jiang et al [21] NA Du et al [22] < 0.1 Xu et al [23] Aluminum: 0.15-1; silicon: 0.025-0.07 Gao et al [24] <0.1 Judy et al [25] NA Cui and Li [26] <0.7 Wu and Cheng [27] <0.12 Yang et al [28] NA Lelea et al [29] NA Sharp and Adrian [30] NA Baviere et al [31] 1.1-0.24 Kohl et al [32] 0.29-1.3 Hegab et al [33] 0. 16 silica microtubes with smaller diameters of 10-20 lm is studied to verify the rarefaction effect.…”

“…Hegab et al [33] studied refrigerant R134a flow in aluminum rectangular channels with hydraulic diameters of 112-210 lm and relative roughness ranging from 0.16% to 0.89%. Reynolds number ranged from 1280 to 13,000.…”

MicroPIV measurements of turbulent flow in square microchannels with hydraulic diameters from 200μm to 640μm

“…For instance, Hegab et al (2001Hegab et al ( , 2002 performed experiments on single-phase flow in microchannels with hydraulic diameters ranging from 112 lm to 210 lm and aspect ratios from 1.0 to 1.5. They reported transition between Re = 2000-4000 and friction factor results that were slightly lower than the conventional predictions.…”