Numerical Studies for Heat Transfer of Hydrocarbon Fuel with Thermal Cracking

Abstract

Coolant flow and thermal cracking process play key roles in regenerative cooling of a hydrocarbon-fueled scramjet. In order to study the heat transfer and thermal cracking process of regenerative cooling structure, a three dimensional numerical method is established. The Modified Kumar-Kunzru chemical kinetics model consisting of primary reaction and secondary reactions is used to simulate the thermal cracking process. The SIMPLE algorithm is applied to solve the low speed flow field. The data of electrically heated tube tests and a fuel-cooled panel test are adopted to validate the numerical method and chemical model. The comparisons show good agreements between calculated results and test data. The study indicates that the numerical method is an effective tool to investigate the heat transfer and thermal cracking process of regenerative cooling structure for scramjet, and a potential tool to solve the flow design problem. NomenclatureA = flowing area of the tube cross section c p = fluid specific heat capacity at constant pressure d i = the inner diameter of the tube d o = the outer diameter of the tube D k = dissipation term of turbulent kinetic energy k D s = diffusion coefficient of species s h t = total enthalpy (includes the kinetic energy) per unit mass I = the electric current passing through the tube k = turbulent kinetic energy k s = the thermal conductivity of solid wall Δl = the length of one small segment of tube wall m = fluid mass flux m in = mass flux of inlet kerosene Nu = Nusselt number p = fluid pressure p c = critical pressure P k = production term of turbulent kinetic energy k P loss = the thermal loss rate Pr = Prandtl number q = heat flux R i = the electric resistance of one small segment of tube wall Re = Reynolds number T = temperature 1 Ph.D., 2 T air = room temperature T c = critical temperature T iw = the inner wall temperature T f = fluid mean temperature T ow = the outer wall temperature u = fluid velocity x = the Cartesian coordinate Y s = mass fraction of species s= the Kronecker delta λ = thermal conductivity of the fluid μ = fluid viscosity ρ = fluid mean density τ ij = viscous stress tensor ω = specific dissipation rate subscripts i = ith axis in the Cartesian coordinate, species i j = jth axis in the Cartesian coordinate k = quantity related with turbulent kinetic energy k l = laminar s = species s t = turbulent tr = transition ω = quantity related with specific dissipation rate ω

Research status of supercritical aviation kerosene and a convection heat transfer considering thermal pyrolysis

“…Xing et al (2009) and Zhong et al (2009b) studied the kinetic parameters of global reaction of RP-3 at p =2.0–3.9 MPa, T = 663–703 K and p = 3.5–4.5 MPa, T = 700–1100 K. Jiang et al (2013) presented a molecular reaction model with 28 species and 24 reactions, and the computational accuracy was acceptable when the cracking conversion was less than 86%. Furthermore, this chemical cracking mechanism was adopted by Zhao et al (2015), Zhang et al (2015), Xu and Meng (2015a) and Jing et al (2018) to study the impact of pressure on the fuel cracking, thermo-hydrodynamic characteristics and curved regenerative cooling channels, respectively. Hou et al (2013) established a global reaction of one-step thermal cracking based on the proportional product distributions and gaseous-product experiments.…”

“…(2015),Zhang et al (2015),Xu and Meng (2015a) andJing et al (2018) to study the impact of pressure on the fuel cracking, thermo-hydrodynamic characteristics and curved regenerative cooling channels, respectively Hou et al (2013). established a global reaction of one-step thermal cracking based on the proportional product distributions and gaseous-product experiments.…”

Investigation of Pressure Effect on Thermal Cracking of n-Decane at Supercritical Pressures

“…The model is able to predict thermal cracking behaviors of RP-3 at a high conversion up to 86%. Using this molecular kinetic model, numerical studies have been performed to investigate the effects of thermal cracking on the regenerative cooling process. , However, the effect of pressure on the pyrolysis of RP-3 was not included in these researches because of the lack of the necessary kinetic parameters for other pressures.…”