Measurements And Estimations Of Critical Properties Of Advanced Aviation Fuels

Critical temperatures and pressures of fuels are important parameters for rating of merit, which define the phase behaviors,performance and temperature range of fuels applied in the airplanes and hypersonic aircrafts. In addition, they are very useful in the investigation of the thermal degradation or aggregation, and carbon deposit under sub-supercritical conditions of fuels.It is generally difficult to measure the critical data of fuels due to its complex composition, unstable features and higher critical values.In this thesis, various experimental methods and theory to determine critical properties of substance were introduced. One low residence time flow equipment for the measurement of the critical temperatures and pressures of thermal-unstable fluids was designed. It improved the original methods and enlarged the range of temperatures and pressures measured, with the tested temperature as 0~500°C, and tested pressure as 0~5MPa. N-pentane,n-hexane,cyclohexane and n-decane were used as standard reagents to check the reliability of the apparatus. The maximum deviation of temperature and pressures are 0.28°C and 0.006MPa, respectively. These results fully prove that the apparatus is reliable to determine the critical data of thermal unstable fluids. The critical temperatures and pressures of two endothermic hydrocarbon fuels RP-3 and simulate JP-7, one high energy fuels JP-10 and mixtures of JP-10 with methyl cyclohexane (MCH) were determined for the firsttime.In addition, the critical data of endothermic aviation fuels of RP-3 and simulate JP-7 were estimated using 6 methods. The temperature deviation was less than 6.63°C, and the pressure deviations among estimated methods, however, can be as much as 0.828MPa. The maximum relative error of temperatures and pressures were 1.67%and 38.4%, respectively. The API methods, and Riazi and Daubert correlation are relatively reliable.A new method to determine the critical data using high pressure differential scanning calorimetry was proposed, which can inferred the critical temperatures and pressures from various DSC curves under differences measuring pressure. The critical data of n-pentane and JP-10 were obtained from this method, the results were 197.6°C and 3.37 MPa, 423.8°C and 3.60 MPa, respectively. The results were in good agreement with the published data, indicating that this method is reliable in practical...