Helium dilution

Helium dilution

Pulmonary Function Tests

Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017

West (1985) observed: It should be noted that the body plethysmograph and the gas dilution (or washout) method[s] may measure different volumes. The body plethysmograph measures the total volume of gas in the lungs, including any which is trapped behind closed airways and which therefore does not communicate with the mouth. By contrast, the helium dilution and nitrogen washout methods measure only communicating gas, or ventilated lung volume. In young normal subjects these volumes are virtually the same, but in patients with lung disease [OLD] the ventilated volume may be considerably less than the total volume because of gas trapped behind obstructed airways.

Numerical Study of Geometric Effects on Burning Velocity Measurement by Constant Volume Method

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Journal Information

Published in Combustion Science and Technology, 2020

Du Wang, Changwei Ji, Shuofeng Wang, Jinxin Yang, Hao Meng

The adopted reaction mechanism was proposed by Burke et al. (2012) with 9 species 24 elementary reactions (helium dilution). The chemistry was solved by the FLUENT native stiff chemistry solvers. The absolute and relative error tolerance for chemistry integration is set to 1e−10 and 1e−5. For better accuracy, In-Situ Adaptive Tabulation (ISAT) (Pope, 1997) is not applied in current simulation (which is default setting for FLUENT chemistry solver). Transport properties are evaluated by the mixture-averaged way, based on the modified Chapman–Enskog formula (McGee, 1991). Thermal diffusion was taken into consideration.

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Numerical Study of Geometric Effects on Burning Velocity Measurement by Constant Volume Method