Flow characteristics of a metering valve in a pulse tube refrigerator Original Research Article

Flow characteristics through a metering valve, a component in orifice pulse tube refrigerators and double-inlet pulse tube refrigerators, are discussed in this paper. Under the assumption that the inertial and convective terms in the momentum equation for a compressible flow can be neglected compared to the pressure gradient term, an expression is obtained for the transient mass flow rate in terms of the local temperature and pressure as well as pressures across the valve. Depending on where the local pressure and temperature are evaluated, two algebraic expressions for the mass flow rates in terms of the effective area are obtained. The values of the effective areas in these two expressions for different openings of the valve at an oscillating frequency of 1 Hz were evaluated based on pressure and temperature measurements. The results are useful for the numerical simulation of the performance of an orifice pulse tube refrigerator or a double-inlet pulse tube refrigerator.