Introduction of a Supercritical Kerosene Test Bench Based on One-Stage Electric Heater with Large Current
A kind of supercritical kerosene heat transfer test bench was introduced in this article. It uses large current to heat the stainless steel tube directly and then the kerosene flowing inside the tube can be heated. A kind of needle valve is used to adjust the kerosene mass flow rate and a kind of backpressure valve is used to adjust the pressure inside the test tube. Insulating materials are laid at the two sides of the tube to prevent electrical leakage. Heat flux is calculated by measurements of the voltage and current. Kerosene is rapidly heated to high temperatures while the wall temperature is below the safety limit by increasing the tube length and thickness. The electric heater could effectively simulate the heat flux of a scramjet engine chamber with a maximum power of about 28KW. Kerosene within 15g/s could be quickly heated to 1000K with this system.
Endothermic fuels for supersonic ramjet
Greater ease of use and higher density make hydrocarbon fuels an attractive option for hypersonic space transport vehicle, In addition to use of fuel for propulsive purpose, it is used for regenerative cooling of system structures. In order to achieve maximum heat sink, endothermic reactions of the hydrocarbon fuels must be employed to augment fuel enthalpy. This should provide cooling sufficient to allow flight in the range of Mach 4-10 at optimum altitude. For a hydrocarbon fuel blend to be suitable for the hypersonic vehicle it should selectively pursue the most beneficial endothermic reaction for optimum cooling and the reaction products should have high combustion intensity under ramjet and scramjet engine conditions. The problem of formation of deposits/coke by hydrocarbons at higher temperature needs to be resolved. The issues for the development of hydrocarbon fuel for hypersonic vehicle are highlighted in this paper.
Deposit Formation and Mitigation in Aircraft Fuels
The development of a viable strategy for limiting coke deposition involves combining synergistic approaches for suppressing deposit buildup and reducing its impact on performance. Candidate approaches, including selection of favorable operating conditions (viz., pressure, temperature, heat flux, residence time, and passage size) and coke-tolerant heat exchanger designs, were investigated to evaluate their effectiveness and provide a basis for combining them into a single design philosophy. These approaches were evaluated through testing of current jet fuels in single-tubes and segments of heat exchanger configurations at temperatures up to 1000°F, pressures up to 1200 psi and liquid hourly space velocities up to 40,000/h. A key result of this work is the ranking of the importance of heat exchanger operating conditions on carbon deposition, with fuel temperature and those parameters that control species diffusion having the most pronounced impact. Residence time and pressure are of lesser importance. Alternative coke-tolerant heat exchanger designs featuring interchannel communication were evaluated and ranked, with several of these concepts demonstrating improvement over continuous passages.