Experimental investigation of heat transfer in vertical upward and downward supercritical CO2 flow in a circular tube

Kim, Dong Eok; Kim, Moo-Hwan

doi:10.1016/j.ijheatfluidflow.2010.09.001

Cited by 162 publications

(14 citation statements)

References 23 publications

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“…Effective cooling techniques are of great importance in high heat flux applications, such as large parallel computer systems and aircraft combustion chambers. As the temperature and heat load in scramjet applications are very high, effective heat transfer systems and effi- Nanofluids have received considerable attention in thermal science and engineering during the last decade [8][9][10]. By dispersing nanoparticles into hydrocarbon fuel kerosene, the formed nanofluid might be a promising coolant as the nanoparticles can enhance the thermal conductivity of kerosene, especially at high temperatures near the critical point.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental and numerical investigations have been extensively conducted on heat transfer performance of fluids at supercritical pressures, but the previous studies in the open literature are mainly focused on supercritical heat transfer of CO 2 and H 2 O [4][5][6][7][8]. Compared to CO 2 and H 2 O, the database on the convective heat transfer of hydrocarbon fuels is at a relative small scale [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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Heat Transfer Characteristics of Al2O3-Kerosene and Fe3O4-Kerosene Nanofluids Flowing in a Minitube at Supercritical Pressures

Huang¹,

Wu²,

Li³

2018

Int J Astronaut Aeronautical Eng

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Regenerative cooling system is thought to be an effective and practical solution to better thermal management for high heat flux applications. In this paper, the potential of nanofluids as regenerative coolants at supercritical pressures was evaluated. Two-step method was applied to prepare Al 2 O 3-kerosene and Fe 3 O 4-kerosene nanofluids. Then experiments were carried out to study the heat transfer characteristics of nanofluids flowing in a vertical minitube at supercritical pressures. Parametric effects of mass flow rate, heat flux, pressure and particle content on the heat transfer performance are presented. Results show that increasing the flow rate or the working pressure could enhance the heat transfer performances, yet higher heat flux leads to poorer heat transfer performances. Besides, the addition of nanoparticles tend to deteriorate heat transfer at supercritical pressures because deposition of the nanoparticles smoothens the wall roughness and presents an additional thermal resistance. As the particle content increases, the heat transfer performance becomes worse.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heat Transfer Characteristics of Al2O3-Kerosene and Fe3O4-Kerosene Nanofluids Flowing in a Minitube at Supercritical Pressures

Huang¹,

Wu²,

Li³

2018

Int J Astronaut Aeronautical Eng

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“…The model was also validated with supercritical CO 2 data obtained through experiments by Kim et al [31].…”

Section: Carbon Dioxidementioning

confidence: 90%

Heat transfer behaviour of supercritical nitrogen in the large specific heat region flowing in a vertical tube

Negoescu

Al‐Duri

et al. 2017

Energy

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This work investigates the heat transfer behaviour of supercritical nitrogen (SCN) for the ultimate goal of optimal design of cryogenic processes/systems. To this end, a comprehensive numerical study was carried out to evaluate the heat transfer coefficient for SCN flowing in a test section under representative conditions. This paper presents the results for nitrogen flowing vertically upward in a 2 mm diameter smooth tube. CFD simulations were conducted at two supercritical pressures (3.5 and 7 MPa) for low and high mass flux at different heat to mass flux ratios (q/G). The objective is to develop reliable prediction approaches regarding the heat transfer coefficient (HTC) in the large specific heat region using the commercially available CFD software Fluent by employing the k-ε turbulence model with enhanced wall treatment. The effects of relevant parameters such as mass flux and heat flux on heat transfer performance, and the influence of operating pressure are discussed. For example, while the working pressure is close to the critical value, i.e. 3.5 MPa, the high specific heat capacity at pseudo-critical temperature produces a peak in the heat transfer coefficient trend. On the other hand, when the pressure increases to 7 MPa the heat transfer behaviour changes due to the smooth variation of thermophysical properties and as a result the HTC trend does not show a peak even at low heat flux. It is found that the heat transfer process transfers from normal mode to deterioration mode while increasing the heat flux. Fundamentally this deterioration is caused by the variation of thermo-physical properties under high mass flux conditions and by the buoyancy forces for low flow rate.

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“…At present, there is still no consensus on the effects of various parameters on the convective heat transfer, especially in cases with high heat flux (q)/ mass flux (G) ratios. Figure shows three kinds of completely different temperature distributions for various bulk enthalpy values at different mass fluxes, which were derived from Kim [26] (used electric heater, experimental range: G = 285-1200 kg/m 2 s, q = 30-170 kW/m 2 ), Zahlan [27], and Kurganov [28]. At moderate (G = 700 kg/m 2 s; q/G = 0.14 kJ/kg, as seen in Figure b, data from Zahlan [27] (used electrical heater, inlet temperature is 7.1-13.8 °C)) and high (G = 1200 kg/m 2 s, q/G = 0.216 kJ/kg, as seen in Figure c, data from Kurganov [28] (used electric heater, Rein = 2.3 × 10 5 -1.18 × 10 6 )) mass fluxes, deteriorated heat transfer occurred, and a temperature peak appeared in the region of 240-280 kJ/kg.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of Convective Heat Transfer of Supercritical Carbon Dioxide at Low Mass Fluxes

Lei

Zhang

et al. 2017

Applied Sciences

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Featured Application: Supercritical carbon dioxide Brayton cycle, geothermal system, nuclear reactor.Abstract: Significant differences in the heat transfer behaviors of supercritical carbon dioxide in a heated channel have been observed at different mass fluxes. At low mass fluxes, a unique heat transfer characteristic is accompanied by a monotonously smooth temperature variation without any temperature peak, even though the ratio of heat flux to mass flux (q/G) is high. In this study, experimental and numerical investigations explore the hidden mechanism of the peculiar heat transfer characteristics of supercritical carbon dioxide at low mass fluxes in vertically upward tubes with inside diameters (ID) of 5 mm. The range of operating conditions examined within the study include a mass flux (G) between 0-200 kg/m 2 s, and a heat flux (q) of up to 120 kW/m 2 . The parametric effects within these experimental conditions were analyzed on the basis of the obtained heat transfer data. Furthermore, a qualitative modeling force analysis and quantitative numerical simulation of vertical flow at low mass flux reveal the heat transfer mechanism for these temperature profiles. In addition, the distribution of flow parameters and thermo-physical properties (such as shear stress, density, and specific heat) in the near-wall region were also studied. It is found that the heat transfer behavior of supercritical CO 2 at low mass flux is similar to "film boiling" at subcritical pressure, where "vapor-like" fluid occupies the sublayer region. Due to reduced buoyancy, the fluid does not cause enough mixing/instability to bring it to the bulk flow.

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Experimental investigation of heat transfer in vertical upward and downward supercritical CO2 flow in a circular tube

Cited by 162 publications

References 23 publications

Heat Transfer Characteristics of Al2O3-Kerosene and Fe3O4-Kerosene Nanofluids Flowing in a Minitube at Supercritical Pressures

Heat Transfer Characteristics of Al2O3-Kerosene and Fe3O4-Kerosene Nanofluids Flowing in a Minitube at Supercritical Pressures

Heat transfer behaviour of supercritical nitrogen in the large specific heat region flowing in a vertical tube

Experimental and Numerical Investigation of Convective Heat Transfer of Supercritical Carbon Dioxide at Low Mass Fluxes

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