Description : Nusselt number is the ratio of the temperature gradient at the wall to (A) Temperature difference (B) Heat flux (C) That across the entire pipe (D) None of these
Last Answer : (C) That across the entire pipe
Description : Nusselt number is the ratio of the (A) Temperature gradient of the wall to that across the entire pipe (B) Temperature difference to the temperature gradient at the wall (C) Heat flux at the wall to that across the entire pipe (D) None of these
Last Answer : (C) Heat flux at the wall to that across the entire pipe
Description : Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. (A) Sherwood number in mass transfer is analogous to Nusselt number in heat transfer ... heat transfer (D) Reynolds number remains the same in both heat and mass transfer
Last Answer : (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer
Description : Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to ... tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side
Last Answer : (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger
Description : The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is (A) Nusselt number (B) Sherwood number (C) Schmidt number (D) Stanton numbe
Last Answer : (C) Schmidt number
Description : The hydrodynamic and thermal boundary layers will merge, when (A) Prandtl number is one (B) Schmidt number tends to infinity (C) Nusselt number tends to infinity (D) Archimedes number is greater than 10000
Last Answer : (A) Prandtl number is one
Description : The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is (A) 2.36 (B) 4.36 (C) 120.36 (D) Dependent on NRe only
Last Answer : (B) 4.36
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 : Nusselt number for full developed, laminar, constant property flow in a pipe at uniform heat flux is (A) 0.72 (B) 4.364 (C) 18 (D) 83
Last Answer : (B) 4.364
Description : Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Sherwood (B) Schmidt (C) Peclet (D) Stanton
Last Answer : (A) Sherwood
Description : Nusselt number (for forced convection heat transfer) is a function of the __________ number. (A) Prandtl (B) Reynolds (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) & (B)
Description : jH factor for heat transfer depends upon the __________ number. (A) Biot (B) Nusselt (C) Reynolds (D) Prandtl
Last Answer : (C) Reynolds
Description : Nusselt number is a function of Prandtl number and __________ number of fluid in natural convection heat transfer. (A) Grashoff (B) Biot (C) Stanton
Last Answer : (A) Grashoff
Description : Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Schmidt (B) Sherwood (C) Peclet (D) Stanton
Last Answer : (A) Schmidt
Description : Which of the following plays an important role in problems of simultaneous heat and mass transfer (A) Lewis number (B) Schmidt number (C) Prandtl number (D) Sherwood number
Last Answer : (A) Lewis number
Description : The ratio of momentum diffusivity to thermal diffusivity is the __________ number. (A) Prandtl (B) Nusselt (C) Stanton (D) Grashoff
Last Answer : (A) Prandtl
Description : The ratio of kinematic viscosity to thermal diffusivity is called the __________ number. (A) Peclet (B) Prandtl (C) Stanton (D) Nusselt
Last Answer : (B) Prandtl
Description : Cpµ/K is termed as the __________ number. (A) Grashoff (B) Nusselt (C) Prandtl (D) Stanton
Last Answer : (C) Prandtl
Description : . If Prandtl number is greater than the Schmidt number, then the (A) Thermal boundary layer lies inside the concentration boundary layer (B) Concentration boundary layer lies inside the thermal boundary ... (D) Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two
Last Answer : (A) Thermal boundary layer lies inside the concentration boundary layer
Description : Give expression for the following and explain the terms involved. (i) Nusselt number (ii) Prandtl number
Last Answer : 1. Nusselt NumberNNU= hd/k h – fim heat transfer coefficient d - diameter of pipe k – thermal conductivity of fluid 2. Prandtl Number NPR -Cp µ/k Cp– specific heat of fluid µ - viscosity of fluid k – thermal conductivity
Description : In a boiling curve, the peak heat flux is called the __________ point. (A) Nusselt (B) Leidenfrost (C) Boiling (D) Burnout
Last Answer : (D) Burnout
Description : Steady state one dimensional heat flow by conduction as given by Fourier's low does not assume that (A) There is no internal heat generation (B) Boundary surfaces are isothermal (C) Material is anisotropic (D) Constant temperature gradient exists
Last Answer : (C) Material is anisotropic
Description : The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re 0.8 , where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient ... pipe diameter (D) as (A) D-1.8 (B) D-0.2 (C) D0.2 (D) D1.8
Last Answer : (B) D-0.2
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 : Prandtl mixing length is (A) Applicable to laminar flow problems (B) A universal constant (C) Zero at the pipe wall (D) None of these
Last Answer : (C) Zero at the pipe wall
Description : Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is (A) 0.2 (B) 0.4 (C) 0.6 (D) 0.8
Last Answer : (C) 0.6
Description : The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is (A) 1.66 (B) 88.66 (C) 3.66 (D) Dependent on NRe only
Last Answer : (C) 3.66
Description : Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids? (A) Dittus-Boelter equation (B) Sieder-Tate equation (C) Nusselt equation (D) None of these
Last Answer : (B) Sieder-Tate equation
Description : For laminar flow of a shear thinning liquid in a pipe, if the volumetric flow rate is doubled, the pressure gradient will increase by a factor of (A) 2 (B) < 2 (C) > 2 (D) 1/2
Last Answer : (A) 2
Description : Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is (A) 0.1 (B) > 1 (C) < 1 (D) 1
Last Answer : (A) 0.1
Description : At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe? (A) 0.5 (B) < 0.5 (C) > 0.6 (D) < 0.1
Last Answer : (C) > 0.6
Description : The rate of heat transfer is a product of overall heat transfer coefficient, the difference in temperature and the (A) Heating volume (B) Heat transfer area (C) Nusselt number (D) None of these
Last Answer : (B) Heat transfer area
Description : In pipe flow, heat is transferred from hot wall to the liquid by(A) Conduction only (B) Forced convection only (C) Forced convection and conduction (D) Free and forced convection
Last Answer : (C) Forced convection and conduction
Description : Which of the following statement is wrong? (A) A flow whose streamline is represented by a curve is called two dimensional flow. (B) The total energy of a liquid particle is the sum of potential energy, ... (D) A pitot tube is used to measure the velocity of flow at the required point in a pipe.
Last Answer : Answer: Option C
Description : The Prandtl Pitot tube measures the (A) Velocity at a point in the flow (B) Pressure at a point (C) Average flow velocity (D) Pressure difference in pipe flow
Last Answer : (A) Velocity at a point in the flow
Description : The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C
Last Answer : (C) 35°C
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 : Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because (A) Convection becomes important (B) Conduction becomes important (C) Radiation becomes important (D) Sub-cooled boiling occurs
Last Answer : (C) Radiation becomes important
Description : The burnout heat flux in the nucleate boiling regime is not a function of the (A) Liquid density (B) Vapour density (C) Temperature difference (D) Heat of evaporation
Last Answer : (B) Vapour density
Description : jH factor for heat transfer is not a function of the __________ number. (A) Reynolds (B) Nusselt (C) Grashoff (D) Both (B) & (C)
Last Answer : (D) Both (B) & (C)
Description : Which of the following is concerned with both heat and mass transfer? (A) Lewis relationship (B) Nusselt number (C) Kutateladze number (D) Froude number
Last Answer : (A) Lewis relationship
Description : Value of Nusselt number [Nu = (hD/k)] for the heat transfer byconduction from a droplet or a spherical particle to a surrounding stagnant film is (A) 0.5 (B) 2 (C) 10 (D) 100
Last Answer : (B) 2
Description : Nusselt number/Biot number varies (A) Inversely with thermal conductivity (B) Directly with heat transfer co-efficient (C) Directly with thermal conductivity (D) Inversely with the dimension of the solid
Last Answer : (A) Inversely with thermal conductivity
Description : Which of the following is not concerned with the heat transfer? (A) Brinkman number (B) Stanton number (C) Schmidt number (D) Peclet number
Description : Which has the lowest Prandtl number? (A) Liquid metal (B) Aqueous solution (C) Water (D) Lube oi
Last Answer : (A) Liquid metal
Description : Which of the following situations can be approximated to a steady state heat transfer system? (A) A red hot steel slab (having outside surface temperature as 1300°C) exposed to the atmospheric air at ... flowing at the rate of 6 Kg/minute through a copper pipe exposed to atmospheric air at 35°C
Last Answer : (B) 10 kg of dry saturated steam at 8 kgf/cm2 flowing through a short length of stainless steel pipe exposed to atmospheric air at 35°C
Description : For __________ Prandtl number values, the heat conduction will be negligible in the buffer zone. (A) Extremely low (B) Low (C) High (D) No
Last Answer : (C) High
Description : Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. (A) Grashoff (B) Reynolds (C) Both 'a' & 'b' (D) Prandtl & Grashoff
Last Answer : (D) Prandtl & Grashoff
Description : Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of (A) Grashoff number (B) Grashoff number & Reynolds number (C) Reynolds number (D) Grashoff number & Prandtl number
Last Answer : Option D
Description : Fouling factor' used in the design of a multipass shell and tube heat exchanger is a (A) Non-dimensional factor (B) Factor of safety
Last Answer : (B) Factor of safety