Turbulent heat transfer characteristics of supercritical
            <i>n</i>
            ‐decane in a vertical tube under various operating pressures

Li, Yong; Sun, Feng; Sundén, Bengt; Xie, Gongnan

doi:10.1002/er.4602

Cited by 31 publications

(9 citation statements)

References 43 publications

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“…In this work, a simple hydrocarbon fuel, n-decane is recognized and the data were borrowed from the NIST (National Institute of Standards and Technology) as shown in Figure 3. Also, this is demonstrated in Li et al (2019b) and the variation of the thermo-physical properties of the supercritical n-decane changes drastically particularly for the specific heat.…”

Section: Description Of the Numerical Methodsmentioning

confidence: 83%

Effect of wall conduction on the heat transfer characteristics of supercritical n-decane in a horizontal rectangular pipe for cooling of a scramjet combustor

Xie

Sundén

2020

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Purpose The purpose of this paper is to numerically study the influence of wall conduction on the heat transfer of supercritical n-decane in the active regenerative cooling channels. Design/methodology/approach A horizontally placed rectangular pipe with a solid zone and another one without a solid zone were used. A drastic variation of thermo-physical properties was emphatically addressed. After the verification of mesh and turbulence models comparing with the experimental results, a mesh number of 4.5 M and the low Reynolds number SST k-ω turbulence model were chosen. The solution of the governing equations and the acquisition of the numerical results were executed by the commercial software FLUENT 2020 R1. Findings The numerical results indicate that there is a heat transfer deterioration (HTD) potential for the upper wall, lower wall and sidewall with the decrease of mass flux. Due to wall conduction, the distribution of the fluid temperature at spanwise-normal planes becomes uniform and this feature also takes advantage of the relatively uniform transverse velocity. For the streamwise-normal planes, the low fluid temperature appears close to the upper wall at the region near the sidewall and vice versa for the region near the centre. Undoubtedly, the secondary flow at the cross-section plays a crucial role in this process and the relatively cool mainstream is affected by the vortices. Originality/value This study warns that the wall conduction must be considered in the practical design and thermal optimization due to the sensibility of thermo-physical properties to the heat flux. The secondary flow caused by the buoyancy force (gravity) plays a significant role in the supercritical heat transfer and mixed convection heat transfer should be further studied.

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Section: Description Of the Numerical Methodsmentioning

confidence: 83%

Effect of wall conduction on the heat transfer characteristics of supercritical n-decane in a horizontal rectangular pipe for cooling of a scramjet combustor

Xie

Sundén

2020

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“…The numerical method and boundary conditions used in this article is similar to [30]. The commercial software, FLUENT 15.0, is used to solve governing equations.…”

Section: Numerical Methods and Boundary Conditionsmentioning

confidence: 99%

“…The commercial software, FLUENT 15.0, is used to solve governing equations. The mesh structure (Figure 3), numerical calculation condition and the relevant setting can be found in [30]. It is noted that the thermal conductivity of solid zone gives a strong effect to the behaviors of supercritical hydrocarbon fuel.…”

Section: Numerical Methods and Boundary Conditionsmentioning

confidence: 99%

“…The mesh sensitivity is significant for the numerical simulation as well as for the validation of turbulence models. The selected conditions and related settings can be referred to [30]. According to Figure 6, the mesh number of 6.0 M is adopted in all calculations to balance the computational time and the solution precision.…”

Section: Validation Of the Turbulence Model And Mesh Sensitivitymentioning

confidence: 99%

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Numerical analysis of supercritical n-decane upward flow and heat transfer characteristics in the buffer layer of a vertical tube

Sun

Xie

et al. 2019

Numerical Heat Transfer, Part A: Applications

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To explore the behavior and mechanisms of heat transfer deterioration (HTD), the flow and thermal performances of supercritical n-decane in upward vertical tubes are investigated with emphasis on the boundary layer. It is realized that the dramatic variation of the thermophysical properties can cause unconventional heat transfer phenomenon and the change of the density is important in particular. The intensity of the HTD gradually increases once the position of the pseudo-critical temperature lays in the buffer layer region. Correspondingly, the turbulence kinetic energy is significantly suppressed. The large temperature gradient in the buffer layer zone means that the temperature commonly used in existing empirical correlations and based on the wall temperature or bulk temperature is not very appropriate and such an approach leads to poor prediction accuracy of the correlations.

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“…For hypersonic flying vehicles, Endothermic hydrocarbon fuel has been widely considered to be used as the propellant and coolant for thermal protection 1‐4 . The fuel experiences thermal decomposition in the heat exchanger of flow channels to produce small hydrocarbon species and hydrogen 5‐7 .…”

Section: Introductionmentioning

confidence: 99%

Experimental study of ignition behaviors of pyrolysis gas of kerosene‐based endothermic hydrocarbon fuel

2021

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Summary The pyrolysis gas consisting of 29.4% CH4, 21.3% C2H4, 30.8% C2H6, and 18.5% C3H6 in mole fraction is presented, as the surrogate of the actual gaseous pyrolysis products. At the conditions of TC = 877.7‐963 K, PC = 3.22‐4.37 MPa, φ = 0.5 and 1.0, the ignition delays of pyrolysis gas/air (diluted with 52% Ar) have been measured. With TC or PC increasing, the ignition delay time decreases. The auto‐ignition of φ = 1.0 is faster than that of φ = 0.5. Furthermore, two widely used small hydrocarbons chemical mechanisms are validated with the measured results. The USC‐II mechanism can well predict experimental results at high‐T regimes, but fails at low‐T regimes. By sensitivity analysis of temperature, the two elementary reactions C2H6 + OH = C2H5 + H2O (negative sensitivity coefficient) and C3H6 + OH = aC3H5 + H2O (positive sensitivity coefficient) have been identified, which have higher reactivity at low‐T and lower reactivity at high‐T. Considering the extreme uncertainty of rate constants of C3H6 + OH = aC3H5 + H2O, the kinetic parameters have been modified for improving the predictions. The validated results indicate that the optimized mechanism improves predictions of the auto‐ignition behavior at low temperature regimes.

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Turbulent heat transfer characteristics of supercritical n ‐decane in a vertical tube under various operating pressures

Cited by 31 publications

References 43 publications

Effect of wall conduction on the heat transfer characteristics of supercritical n-decane in a horizontal rectangular pipe for cooling of a scramjet combustor

Effect of wall conduction on the heat transfer characteristics of supercritical n-decane in a horizontal rectangular pipe for cooling of a scramjet combustor

Numerical analysis of supercritical n-decane upward flow and heat transfer characteristics in the buffer layer of a vertical tube

Experimental study of ignition behaviors of pyrolysis gas of kerosene‐based endothermic hydrocarbon fuel

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