Study On Coking Property And Heat Transfer For Endothermic Hydrocarbon Fuel Up To Supercritical Pressures

The concept of endothermic hydrocarbon fuels (EF) was proposed to deal with the cooling demands of supersonic aircraft as well as to overcome the shortcoming of liquid hydrogen fuels. The project of EF, aided by National "863" Fund, appears great strategic significance in the fields of national defense and aerospace. We analyzed and summed up the documents of pyrolysis of coking and method for the determination of heat transfer characteristics of liquid fuel. Then we investigated and studied the two problem of EF.Apparatus and method for the determination of heat transfer characteristics of liquid fuel at supercritical condition have been set up in this laboratory, which can be used up to the pressure of 5 MPa and to the temperature of 800℃. Heat transfer data of an endothermic hydrocarbon fuel flowing inside a stainless-steel tube with an internal diameter of 1.0 mm at the pressure range from atmosphere to supercritical condition were obtained. The test shows that the value of heat transfer coefficient decreases with the increase of temperature and increases with the degree of evaporation and cracking of the fuel. There are maximum and minimum values because of the vaporization and cracking of the fuel. Under the supercritical pressure, the maximum or minimum values can't be observed obviously. Except the segment of phase shift, the higher the pressure is, the bigger the number become. The data of heat sink for EF can also be given on this apparatus.We mended cooling simulation system, and set up thimble reactor, measured the quantity of coking by hanging up sheet metal. Saw about changing of coking ability of sheet metal that was conducted by physical or chemical technical, physics discriminate of coke, and influence on coking by reaction time and concentration. The analysis results of soluble coke show that coking in-process product consists of aromatic compound and paraffin. Several kinds of coking-inhibitors were picked out, and the effects of these inhibitors were evaluated. Effects of carbon disulfide and 2,2'-Azo-bis-isobutylonitrile as coking inhibitor are prominence. The mechanism of coking inhibitor was discussed in the last section.