rate
The misting system as the most important part of the mist bioreactor has a significant effect on the growth performance and the production of hairy roots culture. The most effective factor which influences misting rate is the viscosity, density, surface tension and height of medium (Barreras et al., 2002; Knorr et Al., 2004; Avvaru et al., 2006). The ANOVA results of experimental factors are presented in table 3. The results showed that the ultrasonic misting rate (MistUS ) was influenced by medium and heights, either individually or in combination (P = 0.01(.
The effect of liquid height on mist generation (total and ultrasonic), surface evaporation rate, the power consumption of various media are shown in Fig. 4. The results showed that the ultrasonic mist generation rate increased with increasing liquid height, and after that reached to a maximum value and then decreased, this trend is similar for all media. When the liquid height is low on the piezo surface. The mist characteristics change. Instead of forming a relatively homogeneous mist, the diameter of particles are not uniform. In this case, larger diameter droplets form on the liquid surface. (Barreras et al., 2002). The droplets return to the liquid surface after detachment again and a few change of mass reduction was recorded by mass balance. Therefore, the only mass loss of vessels is due to the small fraction of misting. This result had been reasoned by the capillary wave hypothesis by researchers (Lang, 1962). Lang (1962) demonstrates that exciting vibration caused a wave. The peaks of wave tears and the collision and agglomeration of the droplets shortly after leaving the surface caused this uniformity (Lang, 1962). Due to bubble detection in bulk of liquid, Barreras et al., (2002) suggested that the other possible mechanism of misting (cavitation) should be considered for describing of atomization process (Barreras et al., 2002). At a high level of liquid, it seems that the wave damp and the surface stack formation fail to result again low misting rate generation. The maximum misting generation rate (total and ultrasonic) was obtained at the heights of 4, 3, 3, and 3 cm for water, B5, MS, and ½ MS respectively. The highest value of\(\text{Mist}_{\text{US}}\) rate was belonged to MS (\(2.78\times 10^{-2}\ \text{gr}/s\)), on the other hand, the lowest value was obtained for B5 (\(0.52\times 10^{-2}\text{gr}/s\)) at a height of 1 centimeter above piezoelectric. The power consumption analysis was depicted for water and MS as media with the highest misting rate (Fig. 4-A & 4-B). The power consumption increased with the increasing height of liquid above the piezo. The trends are not the same for MS and water due to different chemical compounds. The power consumption for a specified amplitude is proportional to the viscosity of the fluid (Figura & Teixeira, 2007).