Heat transfer and flow stability in a rotating disk/stagnation flow chemical vapor deposition reactor

The flow and heat transfer in a vertical high-speed rotating disk/stagnation flow chemical vapor deposition (CVD) reactor is studied with particular emphasis on the effects of the spacing, {bar H}, between the stationary gas inlet and the rotating disk. A one-dimensional analysis is used to determine the effects of {bar H}, flow rate, and disk spin rate on the gas flow patterns and the heat transfer from the disk; the effects of buoyancy, reactor side walls, and finite disk geometry on these quantities are determined in a two-dimensional analysis. The Navier-Stokes and energy equations are solved for hydrogen over a range of gas flow rates, disk spin rates, axial and radial aspect ratios, for a pressure of 250 Torr, inlet gas temperature of 50 C, and disk temperature of 800 C. The 1D similarity solution results show that the dimensionless heat transfer from the rotating disk, Nu{sub 1D}, depends on SP and Re{sub w} to a much greater extent at smaller spacings than at larger spacings. For SP values of 0.92 and 4.5 and for both spacings studied, Nu{sub 1D} approaches the value for an infinite rotating disk for Re{sub w} {approx} 450, except for the case at SP = 4.5 and A = 0.54 where Nu{sub 1D} is significantly larger. The 1D results also show that for small SP (0.23) there is a significant flow toward r = 0 (the radial component of velocity is negative) which is larger for the smaller value of A. The 2D results show that the effect of inlet velocity (SP) on the radial variation of the disk heat transfer (Nu{sub 2D}) is greater for larger values of A; for both values of A there is greater radial variation of Nu{sub 2D} at the laser value of SP.