Buoyancy effects on supercritical-pressure conjugate heat transfer of aviation kerosene in horizontal tubes

Sun, Xing; Xu, Keke; Meng, Hua; Zheng, Yao

doi:10.1016/j.supflu.2018.05.016

Cited by 52 publications

(13 citation statements)

References 46 publications

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“…where the value of Gr/Re 2 > 0.01, the buoyancy effect cannot be ignored in the heat transfer process and it should be considered in the process of numerical simulation. Figure 12 depicts the buoyancy criteria calculated by the empirical expressions for cases at different operating pressures: (a) Gr/Re 2.7 = 10 −5 used by Jackson and Hall 45 ; (b) Gr/Re 2 = 0.01 adopted by Jiang et al 46 It is found that Gr/Re 2.7 = 10 −5 cannot well indicate the onset and development of the heat transfer deterioration, which is obtained by numerical simulation in this paper, and this conclusion was also been reached in Sun et al 31 However, the buoyancy criterion used by Jiang et al appears to be qualitatively more appropriate. The heat transfer deterioration is first achieved to a serious state at the condition of 3 MPa.…”

Section: Description To the Buoyancysupporting

confidence: 77%

“…Moreover, the increased operating pressure will enhance the heat transfer. Sun et al numerically studied the buoyancy effects at different conditions of the inlet flow direction, heat flux, and tube diameters, and the results showed that the buoyancy plays an important role at the conditions of a low inlet flow velocity, a high surface heat flux, and a large tube diameter. Cheng et al used various tube diameters to explore numerically the heat transfer of supercritical hydrocarbon fuel, and they stated that a larger tube diameter develops the buoyancy effect but diminishes the effect of thermal‐induced acceleration.…”

Section: Introductionmentioning

confidence: 99%

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

Sun

Sundén

et al. 2019

Int J Energy Res

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Summary To explore the effect of the operating pressure on the flow and thermal characteristics in a vertical tube with supercritical n‐decane, the inner wall temperature along the streamwise direction, the applicability of empirical correlations and buoyancy criteria are studied firstly. The mechanisms in views of density distribution, velocity field, turbulence intensity, the thickness of the thermal boundary layer, and secondary flow are then analyzed. It is observed that the buoyancy is helpful for the phenomenon of heat transfer deterioration at lower operating pressures but higher operating pressures can diminish this tendency. According to this reason, the empirical correlation proposed by Bae and Kim is suitable for the higher operating pressures but cannot well predict the occurrence of heat transfer deterioration. However, it can be evaluated by the buoyancy criterion Gr/Re2 = 0.01 qualitatively. The decrease of turbulence intensity, the thickened thermal boundary layer, and secondary flow generation make contributions to the heat transfer deterioration in particular. Similarly, this situation can be diminished and even removed by the higher operating pressures.

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Section: Description To the Buoyancysupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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

Sun

Sundén

et al. 2019

Int J Energy Res

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“…After that, the outflow high-temperature fuel is injected into the combustor as a propellant. As the pressure in the combustion chamber is higher than the fuel's critical pressure, the heat transfer of hydrocarbon fuel in regenerative cooling channels is conducted under supercritical pressures [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Nu b /Nu 0 = 1 + 1.67(T w0 − T pc )/T pc(9) Kang and Chang[38] measured the heat transfer coefficient of supercritical R134a (p cr = 4.01 MPa) flowing in a upward vertical tube. They correlated the 7022 data points within the range of p = 4.1-4.5 MPa, G = 600-2000 kg/m 2 s, and developed the following equation, in which the variations in heat capacity and density are taken into account.Nu b = 0.0244Re 0compares the experimental Nu with the four empirical heat transfer correlations.…”

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confidence: 99%

Experiments on Heat Transfer of Supercritical Pressure Kerosene in Mini Tube under Ultra-High Heat Fluxes

et al. 2020

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Heat transfer of supercritical-pressure kerosene is crucial for regenerative cooling systems in rocket engines. In this study, experiments were devoted to measure the heat transfer of supercritical-pressure kerosene under ultra-high heat fluxes. The kerosene flowed horizontally in a mini circular tube with a 1.0 mm inner diameter and was heated uniformly under pressures of 10–25 MPa, mass fluxes of 8600–51,600 kg/m2 s, and a maximum heat flux of up to 33.6 MW/m2. The effects of the operating parameters on the heat transfer of supercritical-pressure kerosene were discussed. It was observed that the heat transfer coefficient of kerosene increases at a higher mass flux and inlet bulk temperature, but is little affected by pressure. The heat transfer of supercritical-pressure kerosene is classified into two regions: normal heat transfer and enhanced heat transfer. When the wall temperature exceeds a certain value, heat transfer is enhanced, which could be attributed to pseudo boiling. This phenomenon is more likely to occur under higher heat flux and lower mass flux conditions. In addition, the experimental data were compared with several existing heat transfer correlations, in which one of these correlations can relatively well predict the heat transfer of supercritical-pressure kerosene. The results drawn from this study could be beneficial to the regenerative cooling technology for rocket engines.

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“…Detailed process description on the regenerative cooling technique can be found in [4]. Generally, the critical pressure of hydrocarbon fuels is 2 and 3 MPa and they always work at supercritical condition due to the operating pressure 3.5-7.0 MPa of the combustor [5,6]. As is well known, the physical properties of supercritical hydrocarbon fuels change drastically at supercritical conditions.…”

Section: Introductionmentioning

confidence: 99%

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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Buoyancy effects on supercritical-pressure conjugate heat transfer of aviation kerosene in horizontal tubes

Cited by 52 publications

References 46 publications

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

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

Experiments on Heat Transfer of Supercritical Pressure Kerosene in Mini Tube under Ultra-High Heat Fluxes

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

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