2.4 Mist generation system performance
The measurements performed at a given height. The different height of
the liquid above the ultrasonic transducer was adjusted to 1, 2, 3, 4,
5, 6, and 7 cm ± 0.1. The mist was decelerated by gravity effect, the
mist particles would come to a stop in only 2 mm over the liquid surface
(Barreras et al., 2002). This dense fog should be transmitted by the air
force for further application. The inlet airflow rate was set at 25
lit/min at a pressure of 2 bar when it was required. During the misting
mode of operation, the total lost weight of medium, Mist total, occurred
by airflow (surface evaporation, Mist air ) and
ultrasonic effect (Mist US ). In order to evaluate
the performance of the misting system and determine the contribution of
ultrasonic transducer (Mist US ) accurately, at
first the surface evaporation of medium was determined (Mistair ). To obtain Mist air ,
the air was blown on the quiescent medium when the ultrasonic transducer
was turned off. The exhaust gas momentum and its heat transfer lead to
accelerating the surface evaporation of the solution in the mist chamber
and caused weight loss that was due to surface evaporation. The slope on
mass-time variations was presented as mass flow loses caused by surface
evaporation (equation 4). To ensure to have a stable condition of the
weight loss, the middle three-minute period of the weight loss-time
chart was considered (Fig. 2). The value of MistUS determined indirectly by knowing the Misttotal and Mist air , then
the Mist US was obtained by equation 5. To obtain
the Mist total and
Mist air , the system only was run for 6 minutes
at a given height of 1, 2, 3, 4, 5, 6, or 7 cm.