Abstract
The thesis of this study is to investigate that the measurement accuracy of the isothermal discharge method for hydrogen gas with an isothermal tank which is designed for measuring the flow-rate characteristics of pneumatic components. Compressed gas in an isothermal tank, which is combined three types of orifice, is discharged from 700kPa(abs) to atmospheric pressure. The average temperature in the tank during discharge is measured experimentally. Experimental results and the measurement errors of the isothermal discharge method in hydrogen and air are compared. In consequence, when hydrogen and air is discharged with same pressure drop rate respectively, the temperature change in hydrogen is less than the one in air. When the maximum discharge rate is 35.6kPa/s during discharge hydrogen, the measurement error is less than 3% in whole discharge time. The difference between the temperature change in hydrogen and air is discussed qualitatively in the view point of the relation among Nusselt number, Reynolds number and Prandtl number. As a result, it is investigated that the heat exchange between hydrogen and copper wire is five times larger than the one between air and copper wire.
