| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 87 === An experimental investigation of micro channel flow was performed. The relationship between pressure loss and flow rate was determined for Helium gas in micro channels of different dimensions and configurations. Three types of micro channels were fabricated: CNC machined micro channels (500μm wide, 80μm deep, and 25.4mm long), chemically etched micro channels (100μm~400μm wide, 5.40μm~11.49μm deep, and 10 mm long), and commercial capillary tubes (inner diameter: 20μm, length: 50mm). The methods and techniques for the fabrication and assembly of CNC machined and chemically etched micro channels were discussed in detail in this thesis. The depth variation in the longitudinal direction of the CNC machined channels was found to be about 15μm which was greater than 1/5 of the channel depth. As a result only the other two types of micro channels were tested in the present study. Experimental data of different pressure drops indicate that, the flow rates for channel pressures higher than the atmospheric pressure are greater than that of a constant-property flow in a circular tube. The deviation from constant-property result increases with the pressure difference across the channel. On the contrary the measured flow rate was lower than the constant-property result when the channel pressure was below the atmospheric pressure. The mean free paths of gases in the low-pressure experiments were comparable with the channel depth. Consequently micro-scale effects such as the slip boundary condition might become important. A simple analytical formula was developed in the present study for predicting the relationship between pressure loss and flow rate for micro channels of different configurations with the slip-flow effect taken into consideration.
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