| Summary: | 碩士 === 國立臺灣大學 === 機械工程學系 === 86 === In this paper, wastewater purification on the freezing
phenomenon of falling
film was studied. An aluminum plate was adopted as the cooling vertical wall in
the experimental system, and the test section was thermally insulted to reduce
the thermal convection caused by the outside air, hence improve the heat and
mass transfer of the falling film, and raise the degree of
purification (COD of the
wastewater / COD of the ice) up to the standard of more than 30.
In the present study, the dependence of the freezing phenomenon of falling
film and the degree of purification on the controlling parameters which include
the inlet temperature, flow rate, and inlet concentration of
wastewater, the inlet
temperature and flow rate of the refrigerant, the time of ice
formation, and in-sit
washing operation on the ice surface, were investigated under atmospheric
pressure. Ethyl alcohol solution was adopted as a refrigerant
in the experimental
system.
The results of the experimental studies show that the
degree of purification
could be upgraded over 30 with the inlet temperature of wastewater lower than
4C, the Reynolds number of wastewater ranging from 250 to 350, the inlet
temperature of the refrigerant ranging from -3C to -4C, the Reynolds number
of the refrigerant ranging from 400 to 550. Furthermore, the in-situ washing
operation on the ice surface has the positive effect on the
degree of purification
|
|---|
