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

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.

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

2011 ◽  
Author(s):  
Kyohei Isobe ◽  
Chungpyo Hong ◽  
Yutaka Asako ◽  
Ichiro Ueno
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Wall Temperature ◽  
Gas Flow ◽  
Tube Diameter ◽  
Turbulence Energy ◽  
Stagnation Temperature ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Turbulent Gas Flow

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.

Heat Transfer Characteristics of Compressible Laminar Flow Through Microtubes

2011 ◽  
Vol 134 (1) ◽  
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.

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

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

Total Temperature Measurement of Turbulent Gas Flow at Microtube Exit

2013 ◽  
Author(s):  
Chungpyo Hong ◽  
Kyohei Isobe ◽  
Yutaka Asako ◽  
Ichiro Ueno
Keyword(s):  
Heat Transfer ◽  
Temperature Measurement ◽  
Wall Temperature ◽  
Gas Flow ◽  
Constant Wall Temperature ◽  
Circulating Water ◽  
Total Temperature ◽  
Flow Through ◽  
Exit Mach Number ◽  
Turbulent Gas Flow

This paper describes experimental results on total temperature measurement to obtain heat transfer characteristics of turbulent gas flow in a microtube with constant wall temperature. The experiments were performed for nitrogen gas flow through a microtube of 354 μm in diameter with 100 mm in length. The wall temperature was maintained at 310 K, 330 K, and 350 K by circulating water around the microtube, respectively. The stagnation pressure was chosen in such a way that the exit Mach number ranges from 0.1 to 1.0. In order to obtain heat transfer rate of turbulent gas flow through a micro-tube, the total temperatures of gas flowing out of a microtube exit were measured with the set of total temperature measurement attached to micro stage with position fine adjustment. The numerical computations based on the Arbitrary - Langrangian - Eulerian (ALE) method were also performed for the turbulent gas flow with the same conditions of the experiments. The results were in excellent agreement.

Heat Transfer Characteristics of Turbulent Gas Flow Through Micro-Tubes

2010 ◽  
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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