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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 hydrogen in an isothermal tank, which is combined three types of orifice, is discharged from 700 kPa (abs) to atmospheric pressure. The average temperature in the tank during discharge is measured experimentally. In consequence, when the maximum discharge rate is 37 kPa/s during discharge hydrogen, the measurement error is less than 3% in whole discharge time. The temperature response phenomenon in hydrogen is discussed qualitatively in the view point of the internal energy change. The internal energy change immediately after the discharge started was negative because the release enthalpy was larger than the quantity of heat obtained from the stuffing material. After a certain period of time elapsed, the enthalpy change became equal to the heat exchange between the internal hydrogen and the stuffing material. [Copyright &y& Elsevier]

In this paper, a new isothermal tank test circuit composed of two tanks and a new data-processing algorithm called Cbm method are proposed to measure the flow-rate characteristics of some pneumatic valves. The double-tank circuit is used to test some solenoid valves such as inner pilot solenoid, which the traditional isothermal discharge method can not apply to. And Cbm method changes the identification procedure of multivariable unconstrained optimal algorithm, which evidently improves the identification precision of critical pressure ratio and subsonic index. [ABSTRACT FROM AUTHOR]