Analysis of unsteady heat and mass transfer during the modified chemical vapor deposition process

摘要

An analysis of unsteady heat and mass transfer in the Modified CHemical Vapor Deposition has been carried out. It is found that commonly used quasi-steady state assumption could be used to predict overall efficiency of particle deposition, however, the assumption would not be valid near the inlet region where tapered deposition occurs. The present unsteady claculations have been found to be capable of predicting detailed deposition pofile correctly even from the inlet region where further optimization is needed at the real practice. The present results have also been compared with the existing experimental data and were in good agreement. It is noted that previous quasi-steady calculation resulted in a significant difference in deposition profile near the inlet region. The effects of time varying torch speeds were also studied. Linearly varying torch speed case until time chemical bounds 120s resulted in a much shorter tapered entry than the constant torch speed case.