28 September 2001 Experimental investigation of flow and heat transfer characteristics of R-134a in microchannels
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Proceedings Volume 4560, Microfluidics and BioMEMS; (2001) https://doi.org/10.1117/12.443049
Event: Micromachining and Microfabrication, 2001, San Francisco, CA, United States
Fluid flow and heat transfer characteristics of single-phase flows in microchannels for refrigerant R-134a were experimentally investigated. Experiments were conducted using rectangular channels micro-milled in aluminum with hydraulic diameters ranging from approximately 112-mm to 210-mm and aspect ratios that varied from 1.0 to 1.5. Using overall temperature, flow rate, and pressure drop measurements, friction factors and convective heat transfer coefficients were experimentally determined for steady flow conditions. Reynolds number, relative roughness, and channel aspect ratio were the parameters examined in predicting friction factor and Nusselt number for the experiments. Experiment results indicated transition from laminar to turbulent flow occurred between a Reynolds number of 2,000-4,000. Friction factor results were consistently lower than values predicted by macroscale correlations. Nusselt number results indicated channel size may suppress turbulent convective heat transfer. Results also indicate that surface roughness may affect heat transfer characteristics in the turbulent regime.
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Hisham E. Hegab, Hisham E. Hegab, Abdullahel Bari, Abdullahel Bari, Timothy A. Ameel, Timothy A. Ameel, } "Experimental investigation of flow and heat transfer characteristics of R-134a in microchannels", Proc. SPIE 4560, Microfluidics and BioMEMS, (28 September 2001); doi: 10.1117/12.443049; https://doi.org/10.1117/12.443049

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