CALCULATION OF REAL GAS EFFECTS IN THE DEPRESSURIZATION OF AN AIR STORAGE CYLINDER.
NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER ANNAPOLIS MD ANNAPOLIS DIV
Pagination or Media Count:
An analytical study was made of the depressurization of air from a highly pressurized 500 to 5000 psi air storage cylinder through a nozzle when real gas and heat transfer effects are not negligible. A virial coefficient equation of state is used to obtain general expressions for the thermodynamic properties of the gas. These property relationships are used in the numerical solution of the quasi- steady energy equation of the flask air. Results are parametrically compared to the perfect gas situation under various conditions when the virial coefficients of the real gas are those of the Beattie-Bridgeman equation of state. The separate effects of caloric and thermal gas imperfection are evaluated, and it was found that caloric imperfections are small compared to the thermal imperfections. Hence, it was concluded that the specific heats may be used as constants throughout the blowdown without seriously affecting the results. Also, it was found that van der Waals equation of state expressed in the virial equation form gave results which did not differ greatly from the results predicted by the Beattie-Bridgeman equation. Thus, the van der Waal form is preferred in numerical calculations since there is a considerable saving of computing time by using this shorter equation. A series of experiments was run to verify the analytical predictions. The test data compared favorably with the analytical predictions. Differences between the two are attributed, for the most part, to inaccurate heat transfer coefficient prediction and to errors in the temperature measurement. Author
- Miscellaneous Materials