Experimental study on slip flow of nitrogen through microchannels at atmospheric pressure

Gas flows through microchannels are commonly involved in various micro-electro-mechanical systems devices. Unlike the conventional flows at the macroscopic scale, micro-scale gas flows often show significant slip characteristics. This study designed a gas micro-flow measurement system based on the double-tank constant volume method to investigate the flow behaviors of gases through microchannels. The measurement system has a minimum mass flow rate resolution of 10 - 11 kg/s, which can meet the requirements of micro–nano-scale gas flow monitoring. We then investigated the slip flow characteristics of nitrogen in the microchannels at atmospheric pressure. The experimental data agreed well with the theoretical results based on the slip flow theory, which confirmed the existence of velocity slip in microchannels. In addition, we extracted the tangential momentum accommodation coefficients (TMAC) from the measured mass flow rates for different experimental conditions. The results showed that, in our experiment, the TMAC value ranged from 0.84 to 0.96 and tended to decrease with decreasing microchannel size.