The local surface conductance for laminar film condensation on
vertical surface is (where, t = film thickness)
(A) ∝ t
(B) ∝ 1/t
(C) ∝ √t
(D) Independent of 't
Description : The film thickness for laminar film condensation on vertical surface __________ from top to bottom. (A) Cumulatively increases (B) Cumulatively decreases (C) Remain constant (D) And the surface conductance increase
Last Answer : (A) Cumulatively increases
Description : According to Arrhenius equation of temperature dependency of rate constant for an elementary reaction (A) k ∝ √T (B) k ∝ e -E/RT (C) k ∝ T e -E/RT (D) None of these
Last Answer : (B) k ∝ e -E/RT
Description : Transition state theory relates the above quantities as (A) k ∝ e -E/RT (B) k ∝ T.e E/RT (C) k ∝ √T (D) k ∝ T 1.5
Last Answer : (B) k ∝ T.e E/RT
Description : Rate constant 'k' and absolute temperature 'T' are related by collision theory (for bimolecular) as (A) k ∝ T 1.5 (B) k ∝ exp(-E/RT) (C) k ∝ √T (D) k ∝ T
Last Answer : (C) k ∝ √T
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 : In turbulent flow, a rough pipe has the same friction factor as a smooth pipe (A) In the zone of complete turbulence (B) When the roughness projections are much smaller than the thickness of ... ) Everywhere in the transition zone (D) When the friction factor is independent of the Reynold's number
Last Answer : (B) When the roughness projections are much smaller than the thickness of the laminar film
Description : The drying time between fixed moisture contents within the 'constant rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 1.5 (D) T
Last Answer : (B) T
Description : The drying time between fixed moisture content within diffusion controlled 'falling rate period' is proportional to (assuming that drying occurs from all surfaces of the solid) (where, T = thickness of the solid). (A) √T (B) T (C) T 2 (D) T
Last Answer : (C) T
Description : The energy radiated from a surface Q at absolute temperature T is related as (A) Q ∝ T 2 (B) Q ∝ T 4 (C) Q ∝ T 3 (D) None of these
Last Answer : (B) Q ∝ T
Description : In the complete turbulence zone (in rough pipes), the (A) Rough and smooth pipes have the same friction factor (B) Laminar film covers the roughness projections (C) Friction factor depends upon NRe only (D) Friction factor is independent of the relative roughness
Last Answer : (D) Friction factor is independent of the relative roughness
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 : At low Reynold's number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: Po = ρ/ρN3 D5 : Power number Re = ρ N D2 ... Re -1.0 (B) Po ∝ Re 0.0 (C) Po ∝ Re 0.5 (D) Po ∝ Re 1.0
Last Answer : (B) Po ∝ Re 0.0 (C) Po ∝ Re 0.5
Description : The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake) (A) ∝ ΔP (B) ∝ 1/ ΔP (C) ∝ √ΔP (D) Independent of ΔP
Last Answer : (D) Independent of ΔP
Description : The thickness of condensate layer in filmwise condensation depends on the (A) Condensation rate (B) Surface configuration (C) Liquid flow rate from the surface (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pick out the wrong statement. (A) Reciprocal of the resistance to heat flow is called thermal conductance (B) Unit of thermal conductance is W/°K (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A (D) None of these
Last Answer : (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A
Description : Conductance is given by (where, x = thickness, A = heat flow area, K = thermal conductivity.) (A) x/KA (B) KA/x (C) K/Ax (D) A/Kx
Last Answer : (B) KA/x
Description : In case of liquids, the binary diffusivity is proportional to (where, T = temperature) (A) T (B) √T (C) T 2 (D) 1/T
Last Answer : (A) T
Description : The Knudsen diffusivity is proportional to (where, T = absolute temperature) (A) √T (B) T 2 (C) T (D) T 4
Last Answer : (A) √T
Description : In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where, T = absolute temperature). (A) 1/√T (B) 1/T (C) √T (D) T
Last Answer : (C) √T
Description : From collision theory, the reaction rate constant is proportional to (A) exp (-E/RT) (B) exp (-E/2RT) (C) √T (D) T m exp (-E/RT)
Last Answer : (D) T m exp (-E/RT)
Description : Knudsen diffusion is directly proportional to (A) T (B) √T (C) 1/√T (D) T
Last Answer : (B) √T
Description : Translational kinetic energy of molecules of an ideal gas is proportional to (where, T = absolute temperature of the gas) (A) T (B) √T (C) T2 (D) 1/√T
Description : Which of the following represents the Virial equation of state? (A) T = [RT/(V- b)] - [a/√T. V(V + b)] (B) PV/RT = 1 + (B/V) + (C/V2) + …… (C) n1u2 + μ2μ1 = 0 (D) None of these
Last Answer : (B) PV/RT = 1 + (B/V) + (C/V2) + ……
Description : Velocity of a gas in sound is not proportional to (where, T = Absolute temperature of the gas. P = Absolute pressure of the gas. y = Ratio of specific heats (Cp/Cv) ρ = specific weight of the gas) (A) √T (B) 1/√P (C) √y (D) 1/√ρ
Last Answer : (B) 1/√P
Description : The diffusivity (D) in a binary gas mixture is related to the temperature (T) as (A) D ∝ T (B) D ∝ T 0.5 (C) D ∝ T 1.5 (D) D ∝ T
Last Answer : (C) D ∝ T 1.5
Description : Charles' law for gases states that (A) V/T = Constant (B) V ∝ 1/T (C) V ∝ 1/P (D) PV/T = Constant
Last Answer : (A) V/T = Constant
Description : The laminar boundary layer thickness in zero pressure gradient flow over a flat plate along the x-direction varies as x0.5 while the thickness of turbulent boundary layer varies as (where, x = distance from the leading edge) (A) x1.5 (B) x0.8 (C) x-1.5 (D) x-0.8
Last Answer : (B) x0.8
Description : Film condensation is promoted on a/an __________ surface. (A) Oily (B) Coated (C) Clean & smooth (D) Dirty
Last Answer : (C) Clean & smooth
Description : Pick out the correct statement about the condensation. (A) Filmwise condensation gives a lower heat transfer rate than the dropwise condensation (B) Suitable coating or vapour additive is used to promote film ... place on it (D) Reynolds number of condensing liquid is based on its mass flow rate
Last Answer : (B) Suitable coating or vapour additive is used to promote film wise condensation
Description : The thickness of oxide film is y at time t. If K1, K2 and K3 are the temperature dependent constants, the parabolic law of oxidation is given by (A) y2 = 2k1t + k2 (B) y = k1 ln (k2t + k3) (C) y = k1 t + k2 (D) y = k1t3 + k2
Last Answer : Option A
Description : A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The ... . ρL (C) ½w 2 . δρL (2R + δ) (D) ½w 2 . R . ρL(R + 2δ)
Last Answer : (C) ½w 2 . δρL (2R + δ)
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 thickness of a laminar boundary layer over a flat plate at two different sections P and Q are 0.8 cm and 2.4 cm respectively. If the section Q is 3.6 m downstream of P, the distance of section P from the leading edge of the plate is (a) 0.32 m (b) 0.22 m (c) 0.40 m (d) 0.53 m
Last Answer : Ans: (c) Correct Answer is: 0.45 m
Description : In a T-beam, the vertical distance between the bottom of the flange and the centre of the tensile reinforcement is (a) Breadth of flange (b) Thickness of flange (c) Breadth of slab (d) Depth of rib
Last Answer : (d) Depth of rib
Description : Nusselt number is related to Grashoff number (Gr) in turbulent & laminar flow respectively, in respect of free convection over a vertical flat plate as (A) Gr0.25, Gr (B) Gr0.25, Gr0.33 (C) Gr, Gr0.25 (D) Gr0.33, Gr0.25
Description : the oil, N = Speed of the shaft, R = Radius of the shaft, and t = Thickness of the oil film) (A) 60t (B) 60t (C) 60t (D) 60t
Last Answer : Answer: Option D
Description : A thin film having thickness t
Last Answer : (c) Black
Last Answer : C. Black
Description : Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low ... Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers
Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension
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 Prandtl mixing length is (A) Zero at the pipe wall and is a universal constant (B) Independent of radial distance from the pipe axis (C) Independent of the shear stress (D) Useful for computing laminar flow problems
Last Answer : (D) Useful for computing laminar flow problems
Description : The average heat transfer co-efficient over the entire length of the plate (ha ) and the local heat transfer co-efficient (hL ), in case of heat transfer over a flat plate in laminar zone is related as (A) ha = 0.8hL (B) ha = 2hL (C) ha = hL (D) ha = 5hL
Last Answer : (B) ha = 2hL
Description : The most economical channel section for the fluid flow is the one for which the discharge is maximum for a given cross-sectional area. Vertical velocity distribution in an open channel for laminar flow can be assumed to be (A) Parabolic (B) Hyperbolic (C) Straight line (D) None of these
Last Answer : (A) Parabolic
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 : Collision theory gives the rate constant for bimolecular reaction as (A) K α √T.e -E/RT (B) K α e E/RT (C) K α e -E/RT (D) None of these
Last Answer : (C) K α e -E/RT
Description : Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2 .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat ... drop through the exchanger is desired (D) Temperature of the incoming vapor is very high
Last Answer : (B) Supersaturated
Description : If air (a non-condensing gas) is present in a condensing vapor stream, it will __________ the condensation rate of vapor. (A) Increase (B) Decrease (C) Not affect (D) Increase the condensing film co-efficient as well as
Last Answer : (B) Decrease
Description : Presence of a non-condensing gas in a condensing vapour (A) Increases the rate of condensation (B) Decreases thermal resistance (C) Is desirable to increase the film co-efficient (D) None of these
Last Answer : (D) None of these
Description : The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation. (A) Greater than (B) Lower than (C) Is same as (D) Half
Last Answer : (B) Lower than
Description : Mass flow of granular solid (M) through a circular opening of dia, D follows (A) M ∝ √D (B) M ∝ D2 (C) M ∝ D3 (D) M ∝ D
Last Answer : (C) M ∝ D