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
Description : Pick out the wrong statement. (A) The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one (B) Sherwood number for flow in pipes can be expressed ... flux of a component A in binary mixture of A and B is given by - Dab'.dCA/dz
Last Answer : (C) According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(B)P - 3, Q - 2
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 : 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 : 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 : Overall heat transfer co-efficient of a particular tube is U1 . If the same tube with some dirt deposited on either side has coefficient U2 , then (A) U1 = U2 (B) U2 > U1 (C) U1 > U2 (D) U1 = dirt factor - U2
Last Answer : (A) U1 = U2
Description : 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 ... by, y = 5x + 0.001 is (A) 2.0 (B) 1.56 (C) 1.0
Last Answer : (A) 2.0
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 : 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 : 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 : 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 : 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 : 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
Last Answer : (C) Known
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 : 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 : 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 : 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 ... (C) Kc = Kp . RT = Km . RT/p (D) None of these
Last Answer : (C) Kc = Kp . RT = Km . RT/p
Description : For absorbing a sparingly soluble gas in a liquid, the (A) Gas side co-efficient should be increased (B) Liquid side coefficient should be increased (C) Gas side co-efficient should be decreased (D) Liquid side co-efficient should be decreased
Last Answer : (B) Liquid side coefficient should be increased
Description : The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a ... )R = 1.5; (COP)HP = 2.5 (D) (COP)R = (COP)HP = 2.5
Last Answer : (C) (COP)R = 1.5; (COP)HP = 2.5
Description : Co-efficient of velocity is __________ the coefficient of discharge. (A) Less than (B) More than (C) Equal to (D) Not related to
Last Answer : (B) More than
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 : Log mean temperature difference (LMTD) cannot be used, if (A) Heat transfer co-efficient over the entire heat exchanger is not constant (B) There exists an unsteady state (C) The heat capacity is not constant and there is a phase change (D) None of these
Description : Incorrect statement for co-efficient of friction could be that A. The coefficient of friction is denoted by the Greek letter µ. B. The coefficient of friction is directly proportional to ... D. The coefficient of friction is inversely proportional to the force pressing the surfaces together
Last Answer : The coefficient of friction is constant even in the conditions of fast slipping and high contact pressure
Description : Concrete containing (A) Siliceous aggregates, has higher co-efficient of expansion (B) Igneous aggregates, has intermediate coefficient of expansion (C) Lime stones, has lowest co-efficient of expansion (D) All the above
Last Answer : Answer: Option D
Description : Co-efficient of discharge (Cd ) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv ; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about (A) 0.42 (B) 0.62 (C) 0.82 (D) 0.98
Last Answer : (B) 0.62
Description : The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is (A) ∞ (B) 1 (C) 0 (D) -ve
Last Answer : (C) 0
Description : The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same. (A) Kinematic viscosity (B) Work (C) Temperature (D) None of these
Description : Joule-Thomson co-efficient which is defined as, η = (∂T/∂P)H = 1/Cp (∂H/∂T)P, changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is (A) 0 (B) ∞ (C) +ve (D) -ve
Last Answer : (A) 0
Description : Joule-Thomson co-efficient is defined as (A) µ = (∂P/∂T)H (B) µ = (∂T/∂P)H (C) µ = (∂E/∂T)H (D) µ = (∂E/∂P)H
Last Answer : (B) µ = (∂T/∂P)H
Description : The activity co-efficient of the solute in a dilute solution (A) Decreases with the increase of concentration of the solute (B) Increases with the increase of concentration of the solute (C) Remains constant (D) Is unity at infinite dilution
Last Answer : (C) Remains constant
Description : Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if (A) Mass transfer is accompanied by reaction (B ... stagnant medium B (C) Molecular mean free path is high (D) There is equimolar counter diffusion
Last Answer : (D) There is equimolar counter diffusion
Description : Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer coefficient based on the liquid side for dilute systems for the above was estimated to be 4 ... -4 (C) 5.6 10 -3 (D) 8.5 10 -3
Last Answer : (B) 8.5 × 10 -4
Description : An ideal coolant for a nuclear reactor should (A) Be a good absorber of neutrons (B) Be capable of attaining high temperature, only when it is pressurised (C) Have high density, but low heat transfer co-efficient (D) Be free from radiation damage and non-corrosive
Last Answer : (D) Be free from radiation damage and non-corrosive
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 : . 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 : . In a shell and tube heat exchanger, the tube side heat transfer coefficient just at the entrance of the tube is (A) Infinity (B) Zero (C) Same as average heat transfer co-efficient for tube side (D) None of these
Last Answer : (A) Infinity
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 : Heat transfer by natural convection is enhanced in system with (A) High viscosity (B) High co-efficient of thermal expansio
Last Answer : (B) High co-efficient of thermal expansion
Description : Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger ... surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube
Last Answer : (C) S.I. unit of fouling factor is Watt/m2 .°K
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