A. NSc = 1
B. NSc = NPr = NLe
C. NPr = NLe
D. NSc = NLe
Related Mcqs:
- For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG: mass transfer co-efficient, moles/m2, a: interfacial area per unit volume of tower) ?
A. G/(FG . a)
B. FG/(G . a)
C. (G . a)/FG
D. L/(FG . G) - If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution temperature (CST or consolute temperature). If solubilities increase with decrease in temperature, then CST is the temperature below which they dissolve completely. If a binary system has no critical solution temperature, it implies that___________________?
A. The system comprises of partially miscible liquids
B. The system comprises of miscible liquids
C. The system comprises of an azeotrope
D. On heating, a vapor phase will appear; while on cooling, a solid phase will appear - H2S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of H2S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in meters) corresponding to an operating line given by, y = 5x + 0.001 is ______________________?
A. 2.0
B. 1.56
C. 1.0
D. 0.56 - According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity) ?
A. D
B. D2
C. D0.5
D. 1/D - For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is___________________?
A. Calculated
B. Unknown
C. Known
D. Not required - JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by___________________?
A. Nsh = 2
B. Nst = 2
C. Nsc = 2
D. None of these - A 25 cm × 25 cm × 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m × 1m × 1cm flat sheet of the same material is to be dried from one side only. Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is ____________________?
A. 1000
B. 1500
C. 2000
D. 2500 - A packed tower compared to a plate tower for a particular mass transfer operation__________________?
A. Incurs smaller pressure drop
B. Allows installation of cooling coils
C. Is less costly when built in large sizes/diameters
D. Is more suitable, if suspended solids are present in fluid streams - The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp= M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force) ?
A. Kc = Kp = Km
B. Kc = Kp/RT = Km . RT/P
C. Kc = Kp . RT = Km . RT/p
D. None of these - A solid is being dried in the linear drying rate regime from moisture content Xo to XF. The drying rate is zero at X = 0 and the critical moisture content is the same as the initial moisture Xo. The drying time for M = (Ls/ARc) is (where, L = total mass of dry solid, A = total surface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids)) ?
A. M(Xo – XF)
B. M(Xo/XF)
C. M ln(Xo/XF)
D. MXo ln(Xo/XF)
