(6jb) Theoretical Calculation of Ethane Thermal Cracking Temperature

Research Interests: Thermodynamics Properties
and Thermal cracking

Teaching Interests: Power Engineering and Engineering Thermophysics

Theoretical Calculation of Ethane Thermal Cracking
Temperature

Y Song, X Zhao,

MOE Key Laboratory of Thermo-Fluid Science and
Engineering, Xi¡¯an Jiaotong University, Xi¡¯an,
Shaanxi 710049, China

Heat
management problem of an engine has already become increasingly prominent along with
the hypersonic flight vehicle¡¯s use gradually. Fuels provide power as
propellant and serve as coolant
at the same time. Endothermic hydrocarbon fuel is the most promising fuel to
solve heat management problem, which can satisfy engine¡¯s
cooling requirement through thermal cracking that
absorbs heat. Alkanes which have the longer carbon chains would form new
hydrocarbon fuel through cracking under high temperature. However,
thermodynamic properties and combustion
properties of hydrocarbon fuel cause huge changes between and after
cracking. Therefore, research on cracking
temperature and cracked products of alkanes is
vital to engine¡¯ research on cooling characteristic and combustion properties. In order to preliminarily
verify the theoretical calculation model, ethane is used as an example.

This
paper obtains the global chemical reaction equations of ethane which
undergo cracking reaction by means of free radicals
reaction mechanism, some principles of cracking reaction
of ethane and global models mechanism
firstly. Then, the paper obtains theoretical cracking
temperatures under different pressures incorporating Gibbs¡¯ Free Enthalpy. Comparing
calculated cracking temperature with some literature values, for instance, we
know theoretical cracking temperature
of ethane is 1236K and literature value is
1200K under the pressure of 8 MPa. Within
the error allowed, the results with theoretical
calculation are correct.

In conclusion, the
cracking temperature of ethane increases with the
pressure increases, analyzing
the laws between the temperature through theoretical calculation and pressure. Under
lower pressure, cracking temperature increases rapidly with the change of
pressure. Under higher pressure,
cracking temperature¡¯ tendency of increase becomes flat. In addition, compared with
literature data, the theoretical calculation model is correct