Method to Detect Ethylene Glycol in Gaseous Mixtures

摘要

Ethylene glycol is used as a refrigerant for the intake air during simulated altitude testing. There have been some problems during these test because of the ethylene glycol accidentally leaking into the inlet airstream. Since ethylene glycol has at times been suspected of interfering with the test article, its early detection would be greatly beneficial so that testing could be stopped before damage occurs. Because a detection scheme must indicate the presence of ethylene glycol as soon as it appears in the inlet airstream, a spectroscopic technique is preferred over other methods of gas analysis such as sampling and subsequent laboratory analysis. A study was conducted to determine if microwave spectroscopy techniques could be used to monitor the level of ethylene glycol in the inlet airstream to the Engine Test Facility (ETF) test cells during simulated altitude testing. The theory of microwave spectroscopy and the spectra of ethylene glycol are reviewed. Three separate designs of microwave spectrometers are presented which should be capable of monitoring ethylene glycol in the inlet airstreams with a sensitivity of at least 10 ppm.