Browsing by Author "Cheng, Tsung Chieh"

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Pool boiling heat transfer on artificial micro-cavity surfaces in dielectric fluid FC-72
(2006-10-01)
Yu, Chih Kuang
;
Lu, Ding Chong
;
Cheng, Tsung Chieh
;
機械工程學系
;
Department of Mechanical Engineering
The boiling performance and flow mechanism on artificial micro-cavity surfaces with different geometric parameters are presented in the present study. The test surfaces are manufactured on a 625 mu m thick, 10 mm x 10 mm square silicon plate. The treated cavities are all cylinders with three diameters (200, 100 and 50 mu m) and two depths (200 and 110 mu m). The densities of the cavities were designed to be 33 x 33, 25 x 25 and 16 x 16 arrays with 100, 200 and 400 mu m spacings, respectively. The characteristics of heat transfer for pool boiling of FC-72 on artificial micro-cavity surfaces were also examined. In this paper, visualization of the flow patterns was conducted to investigate the characteristics of the bubbles in the growth and departure process. The results indicated that boiling incipience and temperature excursion of silicon-based surfaces are more significant than those of metal-based surfaces reported in the literature. The effects of cavity density are stronger in the high heat flux region than in the low heat flux region because of the bubble/ vapor coalescence near the heating surface. The heat transfer coefficient increases with heat flux and cavity density but a denser cavity will suppress the value of critical heat flux (CHF). Besides, in moderate and high heat flux regions, a larger cavity diameter surface shows earlier decay and a lower peak value of the heat transfer coefficient. The maximum value of CHF on the base area was 3 x 10(5) Wm(-2) (30 W m(-2)) for the test surface with a 33 x 33 cavity array, which is almost 2.5 times that of the plain silicon surface.
Visualization of vortex flow patterns with a uniformly perforated showerhead in a model lamp heat, single-wafer thermal processor
(2007-08-01)
Cheng, Tsung Chieh
;
Lin, Tsing Fa
;
Yang, Jung Yen
;
Jian, Sheng-Rui
;
機械工程學系
Following the rapid progress in the growth of semiconductor thin crystal films, rapid thermal (RT) CVD not only allows for minimization of processing and cycle time, but also enables a significant reduction in the thermal budget. The flow recirculation in the processing chamber driven by the large buoyancy resulting from the temperature differences between the wafer and input gases is known to produce detrimental effects on the film properties. In this study, the proposed 8" rapid thermal processor (RTP) with a showerhead inlet contains three basic types of flow patterns (plug, mixed, and buoyancy-induced flow). The physical parameters, gas flow rate, and pressure of processing chamber are investigated in detail.