Degradation of a Jet A Fuel in a Single-Pass Heat Exchanger

Abstract

The formation of bulk and surface insolubles in a Jet A fuel during a single pass through heated stainless-steel tubes has been studied. Low temperature and low flow rates were utilized to produce near-isothermal conditions. In a second series of experiments, depletion of oxygen in the fuel saturated with respect to room-temperature air was measured under identical isothermal conditions. At a wall/bulk-fuel temperature of 185°C, rates of surface deposition and oxygen depletion were correlated; the maximum in the surface-deposition rate was found to occur after the Jet A fuel was stressed sufficiently that the dissolved oxygen was totally consumed. Results are discussed in terms of the autoxidation of the Jet A fuel and the concurrent production of deleterious bulk and surface insolubles.

Computational Fluid Dynamics Simulations of Jet Fuel Oxidation Incorporating Pseudo-Detailed Chemical Kinetics

“…Figure 4 shows predicted and measured dissolved O 2 fractions at the exit of a heated tube for fuel F2827 flowing at 0.125 mL/min (laminar flow) and for different constant wall temperatures. The experimental measurements 8,14 are for fuel F2827 passing through stainless steel tubes. Different tubes of varying lengths were used to obtain different residence times.…”

“…Fluid dynamics and heat transfer strongly influence jet fuel oxidation, but the nature of this influence is not well understood . For this reason, numerical simulations of dissolved O 2 consumption were performed for the present flow conditions as well as for the flow conditions reported by Jones et al. , in a near-isothermal flowing test rig (NIFTR). In contrast to the conditions of our apparatus, the NIFTR experiments are conducted at lower temperatures and flow rates in order to attain near-isothermal conditions in a minimum length of tube.…”

Model Studies Directed at the Development of New Thermal Oxidative Stability Enhancing Additives for Future Jet Fuels

“…Recent developments in the understanding of high-temperature degradation of jet fuels and model systems can facilitate the development of JP-900. Specifically, Hardy et al, Heneghan et al, and Jones et al have noted an inverse relationship between the temperature at which a fuel absorbs oxygen and the amount of deposit formation during the oxidative degradation of various jet fuels. Fuels that tend to absorb the dissolved oxygen at lower temperatures (such as highly hydrotreated fuels) tend to produce smaller amounts of oxidative deposits (and vice versa).…”

Novel Experimental Approach to Studying the Thermal Stability and Coking Propensity of Jet Fuel

“…Several other experimental rigs with single-tube heat-exchanger configurations have been reported in the literature, for example, the Shell Development Company Heat Transfer Test Rig, the NASA Glenn Research Center Heated Tube Facility, the Phoenix rig of the U.S. Air Force (USAF), − the near-isothermal flowing test rig (NIFTR), − the Australian Defence Science and Technology Organisation (DSTO) Thermal Stability Rig, , the flow reactor of the Pennsylvania State University (PSU) Energy Institute, , various designs from United Technology Research Center (UTRC), ,, and the single-tube heat-exchanger apparatus of the University of Toronto Institute for Aerospace Studies (UTIAS). ,, The test sections of these test rigs employ different methods for heating. For example, the Phoenix, NIFTR, and UTRC rigs embed the test section into a copper block and conductively heat it with an external electrical heater to achieve isothermal heating. ,,− Test sections are also heated directly by flowing electrical current through them to achieve pyrolytic temperatures and constant heat flux in the Shell Heat Transfer Test Rig and others. − A fluidized sand bath is used to heat the submerged test section in the DSTO rig, , whereas the PSU and UTIAS rigs use radiative heating of the test section by electrical tube furnaces. ,, …”