Point Measurements of Noncondensable Gas Concentration in Condensing Systems

Condensation in the presence of noncondensable gases continues to receive considerable attention, most recently in the application to containment performance for advanced passive nuclear reactors. In experiments, it is often desired to make point measurements of noncondensable gas concentrations under conditions where the gas concentration can be small and superheat can be significant. This paper presents test results for a novel miniature psychrometer. The tests and analysis presented here show that a wetted cylindrical body will approach closely the local saturation temperature of an air-steam mixture, under a wide range of flow velocities and superheat levels, even when the bulb is allowed to drip water. This permits local gas concentrations to be measured with high accuracy, particularly when the thermopile method introduced here is used to measure the wet-bulb temperature relative to a reference pure steam temperature generated in a small boiler.