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RISS 인기검색어
- 검색키워드
- 저자 : Tong-Bou Chang (검색결과 7 건)
- 무료
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Tong-Bou Chang,Tsung-Han Lin,Jhong-Wei Huang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6
An experimental investigation is performed into the two-phase spray cooling heat transfer performance of Al 2 O 3 -water nanofluid given three different nanoparticle concentrations (0, 0.001 and 0.05 vol%) and three different spray operating times (10, 20 and 30 hours). The results show that for an Al 2 O 3 concentration of 0 vol% (i.e., pure DI water), the spray operating time has a negligible effect on the heat transfer performance. However, for Al 2 O 3 concentrations of 0.001 and 0.05 vol%, the heat transfer coefficient decreases with an increasing spray operating time. For the nanofluid with 0 vol% Al 2 O 3 , the spray operating time has only a small effect on the surface hydrophilicity. However, for the nanofluids with nanoparticle concentrations of 0.001 and 0.05 vol%, respectively, the surface hydrophilicity increases with an increasing spray operating time. Furthermore, the surface hydrophilicity also increases with an increasing nanoparticle concentration for a given spray operating time. The energy dispersive X-ray spectroscopy (EDS) results reveal the presence of a nanoparticle layer on the sprayed surfaces with a higher heat flux. The thickness of the deposited layer increases with an increasing spray operating time, and leads to a lower heat transfer performance and a higher surface hydrophilicity as a result.
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Tong Bou Chang,Fu Jen Wang 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.11
his study investigates the heat transfer characteristics and entropy generation rate of a condensate film formed on a horizontal plate with suction at the wall. Applying the minimum mechanical energy principle, the dimensionless liquid film thickness along the plate is found to vary as a function of the Rayleigh number, the Jakob number, the Prandtl number and the suction parameter. The governing differential equation of the condensate thickness is solved numerically by using a finite-difference shooting method. Closed-form analytical expressions are derived for the Nusselt number and the dimensionless overall entropy generation number. When there is no suction at the wall, the results obtained from the analytical expression for the Nusselt number are found to be in good agreement with those presented in the literature.
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Heat transfer performance of jet impingement flow boiling using Al₂O₃-water nanofluid
Tong-Bou Chang,Yen-Kai Yang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.4
An investigation is performed into the heat transfer performance of jet impingement flow boiling using Al₂O₃-water nanofluids with Al₂O₃ additions of 0, 0.0001, 0.001 and 0.01 vol%, respectively. It is shown that the heat transfer performance of jet impingement flowboiling using Al₂O₃-water nanofluid is poorer than that obtained when using de-ionized (DI) water as the working fluid. Scanning electronmicroscopy (SEM) and energy-dispersive X-ray spectrometry (EDS) observations reveal that the reduction in the heat transfer performanceis due to the formation of a nano-sorption layer on the heated surface, which results in an increase in the thermal resistance. However, it is shown that by applying acoustic vibration to the heated surface, the formation of the nano-sorption layer is prevented; withthe result that the heat transfer performance obtained using the Al₂O₃-water nanofluids is better than that obtained using pure DI water.
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Film condensation on horizontal tube with wall suction effects
Tong-Bou Chang,Wen-Yu Yeh,Go-Long Tsai 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.12
This study performs a theoretical investigation into the problem of two-dimensional steady filmwise condensation flow on a horizontal tube with suction effects at the tube surface. An effective suction function is introduced to model the effect of the wall suction on the thickness of the liquid condensate film. The local condensate film thickness and the local Nusselt number are then derived using a simple series numerical method. The results show that the Nusselt number varies as a function of the Jakob number Ja, the Rayleigh number Ra, and the suction parameter Sw. It is found that the wall suction effect has a significant influence on the heat transfer performance. An analytical solution is derived for the mean Nusselt number for the case in which the wall suction effect is ignored. Finally, a closed-form correlation is presented for the mean Nusselt number subject to a wall suction effect.
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Joaquin Zueco,Tong-Bou Chang,Osman Anwar Bég 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.5
The two-dimensional steady-state boundary layer flow of an incompressible micropolar fluid in a Darcian porous medium is studied theoretically and computationally. The governing parabolic partial differential equations are reduced to dimensionless form by using a set of transformations, under appropriate boundary conditions. A network simulation method (NSM) solution is presented. Translational velocities (U, V) are found to increase with a rise in Darcy number (Da) and to increase and decrease, respectively, with a rise in micropolar parameter (Er), i.e., Eringen number (ratio of micropolar vortex viscosity to Newtonian viscosity). Micro-rotation is increased with increasing Er and Da values. Translational velocity gradient, ∂U/∂Y and micro-rotation gradient, ∂Ω/∂Y both increase with Darcy number; however, they are both found to decrease with increasing micropolar parameter, Er. The present study finds applications in polymer flows in filtration systems, chemical engineering, biorheology of porous tissue and plastic sheet processing.
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Ru-Li Lin,Tong-Bou Chang,Chih-Chang Liang 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3
An interior spray method is proposed for enhancing the heat transfer performance of a compact rhombus-pitch shell-and-tube spray evaporator. The experimental results show that the shell-side heat transfer coefficient obtained using the proposed spray method is significantly higher than that achieved in a conventional flooded-type evaporator. Four different spray axis incident angles (0°, 45°, 60° and 75°) are tested in order to investigate the effect of the spray inclination angle on the heat transfer performance of the spray evaporator system. It is shown that the optimal heat transfer performance is obtained using a spray axis incident angle of 60°.
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Heat transfer enhancement of pool boiling for a horizontal U-tube using TiO₂-R141b nanofluid
Rong-Horng Chen,Tong-Bou Chang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12
An experimental investigation is performed into the pool boiling heat transfer performance of TiO₂-R141b nanofluid containing 0vol%, 0.0001 vol%, 0.001 vol%, and 0.01 vol% TiO₂ nanoparticles. Scanning electron microscopy (SEM) and energy-dispersive X-rayspectrometry (EDS) observations reveal that some of the TiO₂ nanoparticles adhere to the heated surface during the boiling process. As aresult, the heat transfer performance is poorer than that obtained using pure R141b as the working fluid. Accordingly, a further investigationis performed in which the heated surface is vibrated ultrasonically. It is shown that the ultrasonic vibration creates an acoustic cavitationeffect, which inhibits the formation of the nano-sorption layer and improves the heat transfer performance as a result.
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