20601. In the design of a paddle agitator, the ratio of paddle diameter to tank diameter is normally taken as
20602. The oxygen absorption rate can be determined by
20603. Industrial paddle agitators turn at the speed of
20604. The dynamic technique is based on the
20605. The addition of antifoams to an aerated bioreactor will decrease oxygen transfer rates because antifoams
20606. During fermentation, the saturation concentration of oxygen was reduced from 7 ppm. to 1 ppm. Which one of the following conclusions can be drawn?
20607. If the stirrer speed is too slow, bubbles will accumulate and coalescese under the impeller. This phenomenon is known as a
20608. The maximum solubility of the alkane in the medium is 5 ppm. If the actual dissolved concentration of the alkane in the medium is 1 ppm. what conclusion may be drawn?
20609. Reynolds (Rei) number for the impeller is given by (where Di, stirrer diameter; N, stirrer speed, ρ, density of fluid and μ, viscosity of fluid)
20610. The advantage of axial flow impellers over radial flow impellers is that axial flow impellers
20611. Larger propellers turn at the speed of
20612. A microbial population in a suspension culture will only be limited by oxygen availability if the dissolved oxygen
20613. Which of the following model holds correct for the two-film theory? (where KL is the mass transfer coefficient, DAB diffusivity and Zf film thickness)
20614. Froude number is avoided in calculation of power requirements for low viscosity liquid mixing systems when
20615. A fermentation system has a KLa of 3 s-1 and a C0 of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to
20616. During aeration, a cylindrical reactor had a height of 10 m. Without aeration, the height was 7.5 m. Under these aeration and mixing conditions, the gas hold up in the reactor is
20617. A fermentation system has a KLa of 3 s-1 and a C0 of 5 ppm of O2. If the bulk liquid is saturated with oxygen then the oxygen transfer rate will be equal to
20618. Which of the following would be best described as a radial flow impeller?
20619. Small propellers turn at the speed of either
20620. In aerobic microorganisms cultures radial flow impellers are used because
20621. The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is that
20622. Turbulent flow range of mixing speed is obtained for
20623. For laminar flow, Reynolds number is correlated with power number as (where K, a constant which depends on the container geometry and shape of stirrer; Rei is Reynolds number for agitator; Di, stirrer diameter and N, stirrer speed)
20624. For turbulent flow, Reynolds number is correlated with power number as (where K, a constant which depends on the container geometry and shape of stirrer; Rei, is Reynolds number for agitator; Di, stirrer diameter and N, stirrer speed)
20625. In a bioreactor, if at a particular time the oxygen transfer rate is 23 kg.h-1, then the oxygen uptake will be
20626. Axial flow impellers
20627. Bioreactors, where vortex is formed, another dimensionless number, __________ is useful.
20628. Oxygen transfer rate is increased with an increase in the stirrer speed in aerated bioreactor because
20629. If the stirring speed increased from 300 to 500 rpm leads to an increase in the reaction rate by two folds. Then it may be concluded that
20630. An increase in the heat transfer in the stirred tank reactor will be observed at
20631. In a two-phase system where the continuous phase remains in place, the gas hold up can be expressed as (where Vs and Vt are the superficial gas velocity and bubble rise velocity)
20632. What is the effect of the concentration of dissolved salts and sugars on the oxygen transfer rate?
20633. Which of the following impellers generate a flow parallel to the axis of shaft?
20634. In a tall reactor, oxygen transfer rates will be
20635. Which of the following impeller is used in situation where strong vertical currents are desirable for suspending heavily particles?
20636. Laminar flow range of mixing speed is obtained for
20637. Which of the following number is calculated from the diameter and peripheral speed of the impeller?
20638. A higher liquid height will lead to a higher gas hold up by which the oxygen transfer rate will be
20639. The main function of the dimples provided in the cooling jacket is to
20640. The power required by an agitator operating in a gas-sparged system is
20641. Which of the following will have the largest interfacial area per unit volume?
20642. Which device is commonly used for measuring the rate of rotation (rpm) of the stirrer shaft?
20643. Swirling and vortex formation can be prevented by
20644. Power number is expressed as
20645. The power consumption in a stirring vessel can be assessed by using a
20646. Surface renewal theory predicts that the mass transfer coefficient is
20647. The oxygen transfer rate in a bioreactor will increase if
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