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
Description : Experimental determination of __________ is done by wetted wall column method. (A) Diffusion co-efficient (B) Mass transfer co-efficient (C) NTU (D) None of these
Last Answer : (B) Mass transfer co-efficient
Description : The wetted wall tower is used to determine (A) Individual mass transfer co-efficient (M.T.C.) in gaseous system (B) M.T.C. of individual components in a liquid-liquid system (C) M.T.C. of liquid in liquid-gas system (D) The overall M.T.C. of the system
Last Answer : (A) Individual mass transfer co-efficient (M.T.C.) in gaseous system
Description : Wetted wall tower experiment determines the (A) Molal diffusivity (B) Volumetric co-efficient (C) Mass transfer co-efficient (D) None of these
Last Answer : (C) Mass transfer co-efficient
Description : Measurement of the interfacial area of mass transfer is achieved easily & accurately in case of a __________ column. (A) Spray (B) Packed (C) Bubble cap plate (D) Wetted wall
Last Answer : (D) Wetted wall
Description : Laboratory determination of the diffusivity of vapor is done by __________ method. (A) Wetted wall column (B) Gilliland's (C) Winkelmann's (D) Wike's
Last Answer : (C) Winkelmann's
Description : __________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids. (A) Wetted wall (B) Packed (C) Plate (D) Spray
Last Answer : C) Plate
Description : Out of the following gas-liquid contacting devices, for a given set of operating conditions, gas pressure drop is the least in __________ tower. (A) Wetted wall (B) Bubble cap (C) Perforated tray (D) Packed
Last Answer : (A) Wetted wall
Description : Which of the following gas-liquid contacting devices incurs the least pressure drop for a particular duty? (A) Grid tray tower (B) Perforated tray tower (C) Wetted wall tower (D) Bubble cap tower
Last Answer : (D) Bubble cap tower
Description : Which of the following provides maximum contact surface for a liquidvapour system? (A) Packed tower (B) Bubble-cap plate column (C) Sieve-plate column (D) Wetted wall column
Last Answer : (A) Packed tower
Description : Which of the following is not a unit of mass transfer co-efficient? (A) Moles transferred/ [(time) (area) (mole fraction)] (B) Moles transferred/ [(time) (area) (mass A/mass B)] (C) Moles transferred/ [(time) (area) (pressure)] (D) None of these
Last Answer : (D) None of these
Description : ________ Equation predicts the activity co-efficient from experimental data. (A) Lewis-Randall (B) Margules (C) Van Laar (D) Both (B) & (C)
Last Answer : (D) Both (B) & (C)
Description : As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient (A) Continues to increase (B) Continues to decrease (C) Goes through a minimum (D) Goes through a maximum
Last Answer : (C) Goes through a minimum
Description : A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0 ... that of the un-insulated steam pipe (D) Less than the steam pipe with 5 cms insulation
Last Answer : (B) Less than that of the un-insulated steam pipe
Description : . The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C-1 respectively. The ambient air is at 30°C ... from the outer surface in W.m-2 is (A) 165.4 (B) 167.5 (C) 172.5 (D) 175
Last Answer : (A) 165.4
Description : Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is 3k/l'. If the wall temperature ... wall temperature in degree centigrade? (A) 35.5 (B) 43.75 (C) 81.25 (D) 48.25
Last Answer : (C) 81.25
Description : Which of the following liquid-vapor contacting devices provides maximum contact surface area for a particular duty? (A) Sieve plate column (B) Bubble cap column (C) Randomly packed column (D) Wetted wall column
Last Answer : (D) Wetted wall column
Description : Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In ... layers over a flat plate are of equal thickness, if Schmidt number is equal to unity
Last Answer : (C) For Laminar flow over a plate of length L, the local mass transfer coefficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s
Description : For absorbing a sparingly soluble gas in a liquid (A) Gas side mass transfer co-efficient should be increased (B) Liquid side mass transfer co-efficient should be increased (C) Liquid side mass transfer co-efficient should be decreased (D) Mass transfer co-efficient must be kept constant
Last Answer : (B) Liquid side mass transfer co-efficient should be increased
Description : Mass transfer co-efficient of liquid is (A) Affected more by temperature than that for gases (B) Affected much less by temperature than that for gases
Last Answer : (A) Affected more by temperature than that for gases
Description : Mass transfer co-efficient (K) and diffusivity (D) are related according to film theory as (A) K ∝ D (B) K ∝√D (C) K ∝ D1.5 (D) K ∝ D
Last Answer : (A) K ∝ D
Description : The overall mass transfer co-efficient for the absorption of SO2 in air with dilute NaOH solution can be increased substantially by (A) Increasing the gas film co-efficient (B) Increasing the liquid film co-efficient (C) Increasing the total pressure (D) Decreasing the total pressure
Last Answer : (A) Increasing the gas film co-efficient
Description : Diffusion co-efficient generally depends upon the temperature, pressure & the nature of the components of the system. Its dimension is not the same as that of the (A) Mass transfer co-efficient (B) Thermal diffusivity (C) Kinematic viscosity (D) Volumetric diffusivity
Last Answer : (A) Mass transfer co-efficient
Description : Mass transfer co-efficient is directly proportional to DAB 0.5 , according to __________ theory. (A) Penetration (B) Surface renewal (C) Film (D) None of these
Last Answer : (A) Penetration
Description : Mass transfer co-efficient 'K' according to penetration theory varies with mass diffusivity as (A) D0.5 (B) D (C) 1/D (D) D1.5
Last Answer : (A) D0.5
Description : Mass transfer co-efficient is directly proportional to DAB according to the __________ theory. (A) Film (B) Penetration (C) Surface-renewal (D) None of these
Last Answer : (A) Film
Description : Pick out the wrong statement. (A) Mass transfer co-efficient does not account for gas-liquid diffusion (B) Diffusion co-efficient and mass transfer co-efficient are not same in any mass transfer operation
Last Answer : (A) Mass transfer co-efficient does not account for gas-liquid diffusion
Description : In a vapor-liquid contacting equipment, the overall gas phase mass transfer co-efficient (M.T.C), KG is related to individual co-efficients (KG and KL ) as (A) KG = 1/KG + m/KL (B) 1/KG = 1/KG + m/KL (C) 1/KG = 1/KL + m/KG (D) KG = 1/KL + m/KG
Last Answer : (B) 1/KG = 1/KG + m/KL
Description : Penetration theory relates the average mass transfer co-efficient (K) with diffusivity (D) as (A) K ∝D (B) K ∝√D (C) K ∝D1.5 (D) K ∝D
Last Answer : (B) K ∝√D
Description : Calculation of mass transfer co-efficient is mostly/normally done using __________ theory. (A) Surface renewal (B) Film (C) Penetration (D) None of these
Last Answer : (B) Film
Description : The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc ) for the same system is. (A) 100 (B) 10 (C) 5 (D) 1
Last Answer : (B) 10
Description : The mass transfer co-efficient for a solid sphere of radius 'a' dissolving in a large volume of quiescent liquid, in which ‘D’ is the diffusivity of solute, is (A) D/a (B) D/2a (C) Proportional to √D (D) Dependent on the Reynolds number
Last Answer : (D) Dependent on the Reynolds number
Description : Mass transfer co-efficient is defined as (A) Flux = Co-efficient/concentration difference (B) Co-efficient = Flux/concentration difference (C) Flux=concentration difference/coefficient (D) None of these
Last Answer : (B) Co-efficient = Flux/concentration difference
Description : Pick out the wrong statement. (A) In a first order reaction, A → products; the reaction becomes slower as it proceeds, because the concentration of A decreases and the rate is proportional to the concentration ... irreversible reaction, A + B → 2C is k.CA .CB , then the reaction is always elementary
Last Answer : (C) According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases
Description : Pick out the wrong statement. (A) The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation ( ... in a heat exchanger is controlled by the value of the film co-efficient, which is higher
Last Answer : (D) Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film co-efficient, which is higher
Description : Which of the following equipments is not used for liquid dispersion? (A) Wetted wall towers (B) Packed towers (C) Venturi scrubbers (D) Agitated vessels
Last Answer : (D) Agitated vessels
Description : __________ column is used in gas absorption process. (A) Wetted wall (B) Sieve/perforated tray (C) Bubble cap (D) Packed
Last Answer : (D) Packed
Description : Which one of the following devices is not used for both the absorption as well as the liquid-liquid extraction processes? (A) Packed towers (B) Plate towers (C) Spray towers (D) Wetted wall columns
Last Answer : (D) Wetted wall columns
Description : Which of the following equipments is used for liquid dispersion? (A) Packed column (B) Venturi scrubber (C) Bubble cap plate column (D) Wetted wall column
Last Answer : Option B
Description : . A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because (A) Total heat transfer area of ... in a single effect is much lower than that in any effect in a multi-effect system
Last Answer : (B) Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect
Description : Double pipe heat exchangers are preferably useful, when (A) High viscosity liquid is to be cooled (B) Requirement of heat transfer area is low (C) Overall heat transfer co-efficient is very high (D) A corrosive liquid is to be heated
Last Answer : (B) Requirement of heat transfer area is low
Description : Baffles are provided in heat exchangers to increase the (A) Fouling factor (B) Heat transfer area (C) Heat transfer co-efficient (D) Heat transfer rate
Last Answer : (C) Heat transfer co-efficient
Description : 1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m2 and the overall heat transfer co-efficient to the ... will be (A) 15 min (B) 22 min (C) 44 min (D) 51 min
Last Answer : (D) 51 min
Description : Heat transfer rate per unit area is called (A) Thermal conductivity (B) Heat flux (C) Heat transfer co-efficient (D) Thermal diffusivity
Last Answer : (B) Heat flux
Description : The main purpose of providing fins on heat transfer surface is to increase the (A) Temperature gradient (B) Mechanical strength of the equipment (C) Heat transfer area (D) Heat transfer co-efficient
Last Answer : (C) Heat transfer area
Description : Which of the following parameters is increased by use of finned tube in a multipass shell and tube heat exchanger? (A) Tube side pressure drop and the heat transfer rate (B) Convective heat transfer co-efficient (C) Effective tube surface area for convective heat transfer (D) All (A) (B) and (C)
Last Answer : (D) All (A) (B) and (C)
Description : Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger ... vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area
Last Answer : (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted
Description : For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are (A) Same (B) Different (C) Never different (D) Linearly related
Last Answer : (B) Different
Description : Pick out the correct statement. (A) The slope of the stripping line is always less than unity (B) For a given separation in a binary distillation column, with increase in reflux ratio ( ... (D) Kremser-Brown-Souder's equation is used to calculate the efficiency of a plate tower
Last Answer : C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux
Description : 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 stream
Last Answer : (A) Incurs smaller pressure drop
Description : Pick out the wrong statement. (A) When the concentration difference for the mass transfer becomes zero at the bottom of the gas absorption tower, then the upper end of the operating line touches the ... fixed gas flow rate, the slope of the operating line decreases, in case of gas absorption process
Last Answer : (C) The operating line lies above the equilibrium curve in case of a gas desorber