Experiment of air flow behavior and heat transfer characteristics in microchannels with different aspect ratios

Experiments were conducted to investigate the flow behavior and heat transfer characteristics in minichannels with different aspect ratios. The widths of microchannels are constant of 0.4 mm. The aspect ratios of the microchannels are 2/5, 1/2, 2/3 and 1, respectively. All tests were performed with air. The experiments were completed with the Reynolds number in the range of 200 to 1600. Results of experiments show that the aspect ratios of microchannels have a remarkable effect on the performance of flow behavior and heat transfer characteristics. The friction factors decrease with the increase of the Reynolds numbers. The Poiseuille numbers increase when the Reynolds numbers keep rising. Both of the friction factors and Poiseuille numbers drop as the aspect ratios increase. Nusselt numbers increase as Reynolds numbers increase, but decrease with the increase of aspect ratios. The corresponding empiric equations for the flow resistance and heat transfer characteristics in microchannels with different aspect ratios are fitted.