Effect of Test Pressure on Fuel Thermal Stability Test Methods.
Final rept. Apr 73-Jul 74,
AIR FORCE AERO PROPULSION LAB WRIGHT-PATTERSON AFB OHIO
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The boiling of turbine fuels in contact with the metal surface of the Jet Fuel Thermal Oxidation Tester JFTOT test section was investigated. The boiling inception pressure was determined at several temperatures. Incipient boiling was determined by observing the pressure-temperature combination at which a power increase occurred in order to vaporize the fuel. A glass test housing was used to visually determine the bubble points of the fuels. The initiation of boiling was found to occur at the pressure-temperature combination where an increase in power was required to vaporize the fuel. Thus, the two techniques used produce identical results. The bubble points for various fuels were calculated using ASTM Method D-2889, Calculation of True Vapor Pressure of Petroleum Distillate Fuels. Good agreement exists between the measured bubble points and the calculated bubble points. Data is presented to show that boiling of the fuel may adversely affect the apparent thermal stability breakpoint of the fuel. It is recommended that the JFTOT operating pressure be increased from 400 psig to 500 psig to decrease the probability of fuel boiling in the JFTOT during a test. Based on lower operating pressure of the ASTMCRC Fuel Coker, it is apparent that boiling of JP-4 and Jet B wide-cut fuels is likely under the current jet fuel test conditions of 300400 F. Thus, the Fuel Coker thermal stability breakpoints of wide-cut fuels are likely to be in error. Author
- Test Facilities, Equipment and Methods