Title: 蒸發液膜與層流氣流熱質傳現象之研究
COMBINED HEAT AND MASS TRANSFER IN LAMINAR GAS STREAM FLOWING OVER AN EVAPORATING LIQUID FILM
Authors: 蔡永利
CAI, YONG-LI
林清發
LIN, GING-FA
機械工程學系
Keywords: 蒸發液膜;熱質傳現象;層流氣流;EUAPORATING-LIQUID-FILM;HEAT-AND-MASS-TRANSFER;LANINAR-GAS-STREAM-FLOWING
Issue Date: 1990
Abstract: A combined theoretical and experimental study was conducted to
investigated the evaporative cooling process of a free falling liquid film
evaporating into air stream. Attention was particularly focused on the
latent heat transfer associated with the film vaporization.
In the first place, a numerical analysis was carried out to study the heat
transfer characteristics for a liquid ethanol film falling down along an
insulated vertical plate. The conservation equations for the liquid film
and the induced gas flow were solved simultaneously. Meanwhile an
experimental system was set up to measure the overall cooling of the film.
The measured data are in good agreement with the numerical predictions.
The detailed heat and mass transfer processes in laminar gas stream forced
flowing over a liquid water film were also examined Significant liquid
cooling results for the system with a high inlet liquid temperature, high
gas stream velocity or a low liquid flowrate.
Next, heat transfer enhancement through liquid film vaporization into
mixed convection gas stream were investigated. The wetted plate is
subjected to an uniform heat flux qw". Results show that the evaporative
latent heat transfer depends largely on the inlet liquid temperature TL,in
and wall heat flux qw" Additionally, the Nusselt number NuL were
correlated.
It is noted that heat transfer between the liquid film and gas stream is
dominated by the transport of latent heat in conjuction with the
evaporation of the liquid film.
URI: http://140.113.39.130/cdrfb3/record/nctu/#NT792489067
http://hdl.handle.net/11536/55513
Appears in Collections:Thesis