Numerical Simulation on Heat Transfer Characteristics of Turbulent Gas Flow in Micro-Tubes

Numerical simulations were performed to obtain for heat transfer characteristics of turbulent gas flow in micro-tubes with constant wall temperature. The numerical methodology was based on Arbitrary-Lagrangian-Eulerinan (ALE) method to solve compressible momentum and energy equations. The Lam-Bremhorst Low-Reynolds number turbulence model was employed to evaluate eddy viscosity coefficient and turbulence energy. The tube diameter ranges from 100 μm to 400 μm and the aspect ratio of the tube diameter and the length is fixed at 200. The stagnation temperature is fixed at 300 K and the computations were done for wall temperature, which ranges from 305 K to 350 K. The stagnation pressure was chosen in such a way that the flow is in turbulent flow regime. The obtained Reynolds number ranges widely up to 10081 and the Mach number at the outlet ranges from 0.1 to 0.9. The heat transfer rates obtained by the present study are higher than those of the incompressible flow. This is due to the additional heat transfer near the micro-tube outlet caused by the energy conversion into kinetic energy.

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Convective Heat Transfer of Turbulent Gas Flow in Micro-Tubes With Constant Wall Temperature (Cooled Case)

ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer ◽

10.1115/mnhmt2012-75241 ◽

2012 ◽

Author(s):

Kyohei Isobe ◽

Chungpyo Hong ◽

Yutaka Asako ◽

Ichiro Ueno

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Wall Temperature ◽

Gas Flow ◽

Tube Diameter ◽

Heat Transfer Characteristics ◽

Constant Wall Temperature ◽

Transfer Characteristics ◽

Turbulent Gas Flow ◽

Heated Case

Numerical computations were performed to obtain for heat transfer characteristics of turbulent gas flow in micro-tubes with constant wall temperature whose temperature is lower than the inlet temperature (cooled case). The numerical methodology was based on Arbitrary-Lagrangian-Eulerinan (ALE) method to solve compressible momentum and energy equations. The Lam-Bremhorst Low-Reynolds number turbulence model was employed to evaluate eddy viscosity coefficient and turbulence energy. The tube diameter ranges from 100 μm to 400 μm and the aspect ratio of the tube diameter and the length is fixed at 200. The stagnation temperature was fixed at 300 K and the computations were done for wall temperature, which ranged from 250 K to 295 K. The stagnation pressure was chosen in such a way that the flow is in turbulent flow regime. The results in wide range of Reynolds number and Mach number were obtained. The bulk temperature based on the static temperature and the total temperature of the cooled case are compared with those of heated case and also with temperatures of the incompressible flow. The result shows that different heat transfer characteristics are obtained for each cooled and heated case. A correlation for the prediction of the heat transfer rate of the turbulent gas flow in a micro-tube is proposed.

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Heat Transfer Characteristics of Compressible Laminar Flow Through Microtubes

Journal of Heat Transfer ◽

10.1115/1.4004645 ◽

2011 ◽

Vol 134 (1) ◽

Cited By ~ 6

Author(s):

Chungpyo Hong ◽

Takaharu Yamamoto ◽

Yutaka Asako ◽

Koichi Suzuki

Keyword(s):

Heat Transfer ◽

Wall Temperature ◽

Gas Flow ◽

Atmospheric Condition ◽

Stagnation Temperature ◽

Heat Transfer Characteristics ◽

Constant Wall Temperature ◽

Gaseous Flow ◽

Transfer Characteristics ◽

Flow Through

This paper describes experimental results on heat transfer characteristics of gaseous flow in a microtube with constant wall temperature. The experiments were performed for nitrogen gas flow through three microtubes of 123 μm, 163 μm, and 243 μm in diameter with 50mm in length, respectively. The wall temperature was maintained at 310 K, 330 K, and 350 K by circulating water around the microtube, respectively. The stagnation pressure is chosen in such a way that the exit Mach number ranges from 0.1 to 1.0. The outlet pressure was fixed at the atmospheric condition. The total temperature at the outlet, the inlet stagnation temperature, the mass flow rate, and the inlet pressure were measured. The numerical computations based on the Arbitrary-Lagrangian-Eulerian (ALE) method were also performed with the same conditions of the experiment for validation of numerical results. Both the results are in excellent agreement. In some cases, the total temperatures obtained by the present experimental study are higher than the wall temperature. This is due to the additional heat transfer from the wall to the gas near the microtube outlet caused by the temperature fall due to the energy conversion into the kinetic energy. A quantitative correlation for the prediction of the heat transfer rate of the gaseous flow in microtubes which had been proposed in our previous study (Hong and Asako, 2007, “Heat Transfer Characteristics of Gaseous Flows in a Microchannel and a Microtube with Constant Wall Temperature,” Numer. Heat Transfer, Part A, 52, pp. 219–238) was validated.

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B211 Heat transfer characteristics of turbulent gas flow in micro-tubes

The Proceedings of the Thermal Engineering Conference ◽

10.1299/jsmeted.2010.253 ◽

2010 ◽

Vol 2010 (0) ◽

pp. 253-254

Author(s):

Kyohei ISOBE ◽

Chungpyo HONG ◽

Ichiro UENO ◽

Yutaka ASAKO ◽

Koichi SUZUKI

Keyword(s):

Heat Transfer ◽

Gas Flow ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Turbulent Gas Flow

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Flow and Heat Transfer Characteristics of Turbulent Gas Flow in Microtube with Constant Heat Flux

Journal of Physics Conference Series ◽

10.1088/1742-6596/362/1/012022 ◽

2012 ◽

Vol 362 ◽

pp. 012022

Author(s):

Chungpyo Hong ◽

Yutaka Asako ◽

Shinichi Matsushita ◽

Ichiro Ueno

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Gas Flow ◽

Constant Heat Flux ◽

Heat Transfer Characteristics ◽

Constant Heat ◽

Transfer Characteristics ◽

Flow And Heat Transfer ◽

Turbulent Gas Flow

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Heat Transfer Characteristics of Turbulent Gas Flow Through Micro-Tubes

2010 14th International Heat Transfer Conference, Volume 6 ◽

10.1115/ihtc14-22355 ◽

2010 ◽

Cited By ~ 1

Author(s):

Chungpyo Hong ◽

Yuki Uchida ◽

Takaharu Yamamoto ◽

Yutaka Asako ◽

Koichi Suzuki

Keyword(s):

Heat Transfer ◽

Heat Transfer Rate ◽

Wall Temperature ◽

Transfer Rate ◽

Gas Flow ◽

Gas Flows ◽

Heat Transfer Characteristics ◽

Total Temperature ◽

Flow Through ◽

Turbulent Gas Flow

This paper presents experimental results on heat transfer characteristics of turbulent gas flows though a micro-tube with constant wall temperature. The experiments were performed for nitrogen gas flows through a micro-tube with 242μm in diameter and 50 mm in length. The wall temperature was maintained at 5K, 20K and 30K higher than the inlet temperature by circulating water around the micro-tube, respectively. In order to measure heat transfer rate of gas flow through a micro-tube, the total temperature at a micro-tube exit was measured. The stagnation pressure was chosen in such a way that the Reynolds number ranges from 3000 to 12000. The outlet pressure was fixed at the atmospheric condition. The total temperature at the outlet, the inlet stagnation temperature, the mass flow rate, and the inlet pressure were measured. The heat transfer rates obtained by the present study are higher than those of the incompressible flow. This is due to the additional heat transfer near the micro-tube outlet caused by the energy conversion into kinetic energy. A correlation for the prediction of the heat transfer rate of the turbulent gas flow through a micro-tube was proposed.

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Convective Heat Transfer of Unchoked and Choked Gas Flow in Micro-Tubes

ASME 2014 12th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2014-21740 ◽

2014 ◽

Author(s):

Chungpyo Hong ◽

Yutaka Asako

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Turbulent Flow ◽

Wall Temperature ◽

Gas Flow ◽

Stagnation Pressure ◽

Bulk Temperature ◽

Stagnation Temperature ◽

Computational Domain ◽

Downstream Region

Heat transfer characteristics of unchoked and choked gas flows in micro-tubes with constant wall temperature were numerically investigated both laminar and turbulent flow cases. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian (ALE) method. The Lam-Bremhorst Low-Reynolds number turbulence model was used for turbulent flow. The compressible momentum and energy equations with the assumption of the ideal gas were solved. The computational domain should be extended to the downstream region of the hemisphere from micro-tube outlet. The back pressure was given to the outside of the downstream region. The stagnation temperature is fixed at 300K and the computations were done for the wall temperature which ranges from 305K to 350K. The tube diameter ranges from 50 to 250 μm and tube aspect ratio is 200. The stagnation pressure is chosen in such a way that the flow at micro-tube exit is enough to be fully under-expanded. By increasing the stagnation pressure, the internal flow in the micro-tube is choked and the flow at the micro-tube outlet is under-expanded. Although the velocity remains constant, the mass flow rate (Reynolds number) increases. The results in a wide range of Reynolds number and Mach number were obtained. The bulk temperature based on the static temperature and the total temperature are compared with those of the incompressible flow. A correlation for the prediction of the heat transfer rate of the unchoked and choked gas flow in micro-tubes is proposed.

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