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

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
by

1 Answer

Answer :

(C) 0.6
by

Related questions

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

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

At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the (A) Buffer zone (B) Turbulent core (C) Both (A) and (B) (D) Viscous sub-layer

Description : At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the (A) Buffer zone (B) Turbulent core (C) Both (A) and (B) (D) Viscous sub-layer

Last Answer : (D) Viscous sub-layer

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

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

A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co￾efficient for turbulent flow conditions is proportional to (A) d 0.8 (B) d -0.2 (C) d -1 (D) d -1.8

Description : A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co￾efficient for turbulent flow conditions is proportional to (A) d 0.8 (B) d -0.2 (C) d -1 (D) d -1.8

Last Answer : (B) d -0.2

essure drop (Δp) for a fluid flowing in turbulent flow through a pipe is a function of velocity (V) as (A) V1.8 (B) V-0.2 (C) V2.7 (D) V

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Last Answer : (D) V

At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical? (A) 1 (B) < 1 (C) > 1 (D) None of these

Description : At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical? (A) 1 (B) < 1 (C) > 1 (D) None of these

Last Answer : (A) 1

For __________ Prandtl number values, the heat conduction will be negligible in the buffer zone. (A) Extremely low(B) Low(C) High(D) No

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

Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by h = 0.023 (K/D) (DVρ/µ) 0.8 (CP .µ/k) 0.4 . This is valid for the value of NRe equal to (A) < 2100 (B) 2100-4000 (C) > 4000 (D) > 10000

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Last Answer : (D) > 10000

Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by (A) Eddies current (B) Conduction (C) Convection (D) None of these

Description : Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by (A) Eddies current (B) Conduction (C) Convection (D) None of these

Last Answer : (B) Conduction

Pick out the wrong statement. (A) The form drag is dependent upon the occurrence of a wake (B) The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance (C) An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity (D) Existence of the boundary layer in fluid flow is because of viscosity of the fluid

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Last Answer : (C) An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity

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

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

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

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

Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone. (A) Laminar (B) Transition (C) Both 'a' & 'b' (D) Highly turbulent

Description : Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone. (A) Laminar (B) Transition (C) Both 'a' & 'b' (D) Highly turbulent

Last Answer : (D) Highly turbulent

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 interfacial tension (C) When Henry's law constant is very small, then the mass transfer rate is controlled by the gas film resistance (D) Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers

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Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension

The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are (A) Re.Gz (B) Nu, Pr (C) Nu, Pr, Re (D) Nu, Gz

Description : The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are (A) Re.Gz (B) Nu, Pr (C) Nu, Pr, Re (D) Nu, Gz

Last Answer : (D) Nu, Gz

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 35°C (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 (C) Boiling brine kept in open vessel when the bottom surface temperature of the vessel is maintained constant at 180°C (D) A sub-cooled refrigerant liquid at 8°C flowing at the rate of 6 Kg/minute through a copper pipe exposed to atmospheric air at 35°C

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

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 varies with the pipe diameter (D) as (A) D-1.8 (B) D-0.2 (C) D0.2 (D) D1.8

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

Bulk of the convective heat transfer resistance from a hot tube surfaceto the fluid flowing in it, is(A) In the central core of the fluid(B) Uniformly distributed throughout the fluid(C) Mainly confined to a thin film of fluid near the surface(D) None of these

Description : Bulk of the convective heat transfer resistance from a hot tube surfaceto the fluid flowing in it, is (A) In the central core of the fluid (B) Uniformly distributed throughout the fluid (C) Mainly confined to a thin film of fluid near the surface (D) None of these

Last Answer : (C) Mainly confined to a thin film of fluid near the surface

For turbulent flow of an incompressible fluid through a pipe, the flow rate ‘Q’ is proportional to (Δ P)n, where ΔP is the pressure drop. The value of exponent 'n' is (A) 1 (B) 0 (C) < 1 (D) > 1

Description : For turbulent flow of an incompressible fluid through a pipe, the flow rate ‘Q’ is proportional to (Δ P)n, where ΔP is the pressure drop. The value of exponent 'n' is (A) 1 (B) 0 (C) < 1 (D) > 1

Last Answer : (C) < 1

. In case of turbulent flow of fluid through a circular pipe, the (A) Mean flow velocity is about 0.5 times the maximum velocity (B) Velocity profile becomes flatter and flatter with increasing Reynolds number (C) Point of maximum instability exists at a distance of 2r/3 from the pipe wall (r = pipe radius) (D) Skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more

Description : . In case of turbulent flow of fluid through a circular pipe, the (A) Mean flow velocity is about 0.5 times the maximum velocity (B) Velocity profile becomes flatter and flatter with ... , shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more

Last Answer : (D) Skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more

Nusselt number is a function of Prandtl number and __________ number of fluid in natural convection heat transfer. (A) Grashoff (B) Biot (C) Stanton

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

In case of turbulent flow of a Newtonian fluid in a straight pipe, the maximum velocity is equal to (where, Vavg = average fluid velocity) (A) Vavg (B) 1.2 Vavg (C) 1.5 Vavg (D) 1.8 Vavg

Description : In case of turbulent flow of a Newtonian fluid in a straight pipe, the maximum velocity is equal to (where, Vavg = average fluid velocity) (A) Vavg (B) 1.2 Vavg (C) 1.5 Vavg (D) 1.8 Vavg

Last Answer : (B) 1.2 Vavg

The head loss in turbulent flow in pipe is proportional to(where, V = velocity of fluid through the pipe) (A) V 2 (B) 1/V 2 (C) 1/V (D) V

Description : The head loss in turbulent flow in pipe is proportional to(where, V = velocity of fluid through the pipe) (A) V 2 (B) 1/V 2 (C) 1/V (D) V

Last Answer : (A) V

Transition from laminar flow to turbulent flow in fluid flow through a pipe does not depend upon the (A) Length of the pipe (B) Diameter of the pipe (C) Density of the fluid (D) Velocity of the fluid

Description : Transition from laminar flow to turbulent flow in fluid flow through a pipe does not depend upon the (A) Length of the pipe (B) Diameter of the pipe (C) Density of the fluid (D) Velocity of the fluid

Last Answer : (A) Length of the pipe

Pick out the wrong statement pertaining to fluid flow. (A) The ratio of average velocity to the maximum velocity for turbulent flow of Newtonian fluid in circular pipes is 0.5 (B) The Newtonian fluid velocity in a circular pipe flow is maximum at the centre of the pipe (C) Navier-Stokes equation is applicable to the analysis of viscous flows

Description : Pick out the wrong statement pertaining to fluid flow. (A) The ratio of average velocity to the maximum velocity for turbulent flow of Newtonian fluid in circular pipes is 0.5 (B) The Newtonian ... at the centre of the pipe (C) Navier-Stokes equation is applicable to the analysis of viscous flows

Last Answer : (A) The ratio of average velocity to the maximum velocity for turbulent flow of Newtonian fluid in circular pipes is 0.5

For turbulent flow of Newtonian fluid in a circular cross-section pipe, the ratio of maximum to average fluid velocity is (A) 0.5 (B) 1 (C) 0.66 (D) < 0.5

Description : For turbulent flow of Newtonian fluid in a circular cross-section pipe, the ratio of maximum to average fluid velocity is (A) 0.5 (B) 1 (C) 0.66 (D) < 0.5

Last Answer : (B) 1

he pressure drop per unit length of pipe incurred by a fluid 'X' flowing through pipe is Δp. If another fluid 'Y' having both the specific gravity & density just double of that of fluid 'X', flows through the same pipe at the same flow rate/average velocity, then the pressure drop in this case will be (A) Δp (B) 2Δp (C) Δp 2 (D) Δp/2

Description : he pressure drop per unit length of pipe incurred by a fluid 'X' flowing through pipe is Δp. If another fluid 'Y' having both the specific gravity & density just double of that of fluid 'X', flows through the same pipe ... then the pressure drop in this case will be (A) Δp (B) 2Δp (C) Δp 2 (D) Δp/2

Last Answer : (B) 2Δp

Pick out the wrong statement. (A) Fluid movement under the influence of buoyant forces resulting from change in density takes place in case of natural convection (B) The ratio NNu /NRe . Npr is called the Stanton number (C) The Peclet number is a measure of the ratio of energy transport by convection to that by conduction (D) The Colburn jH factor for heat transfer is given by Nst Npr

Description : Pick out the wrong statement. (A) Fluid movement under the influence of buoyant forces resulting from change in density takes place in case of natural convection (B) The ratio NNu /NRe . Npr is ... convection to that by conduction (D) The Colburn jH factor for heat transfer is given by Nst Npr

Last Answer : (D) The Colburn jH factor for heat transfer is given by Nst Npr

The non-dimensional temperature gradient in a liquid at the wall of a pipe is the (A) Heat flux (B) Nusselt number (C) Prandtl number (D) Schmidt number

Description : The non-dimensional temperature gradient in a liquid at the wall of a pipe is the (A) Heat flux (B) Nusselt number (C) Prandtl number (D) Schmidt number

Last Answer : (A) Heat flux

The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by __________ times, when the number of tube passes is increased to 8. (A) 2 0.8 (B) 4 0.8 (C) 4 0.4 (D) 2 0.4

Description : The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by __________ times, when the number of tube passes is increased to 8. (A) 2 0.8 (B) 4 0.8 (C) 4 0.4 (D) 2 0.4

Last Answer : (B) 4 0.8

In a fully turbulent flow (Re > 10 5 ) in a pipe of diameter 'd', for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is (A) d(B) d2(C) d2.5(D) d

Description : In a fully turbulent flow (Re > 10 5 ) in a pipe of diameter 'd', for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is (A) d (B) d 2 (C) d 2.5 (D) d

Last Answer : (C) d 2.5

Transition length for a turbulent fluid entering into a pipe is around __________ times the pipe diameter. (A) 5 (B) 50 (C) 500 (D) 5000

Description : Transition length for a turbulent fluid entering into a pipe is around __________ times the pipe diameter. (A) 5 (B) 50 (C) 500 (D) 5000

Last Answer : (B) 50

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

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

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

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

Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called (A) Radiation (B) Natural convection (C) Forced convection (D) Conduction

Description : Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called (A) Radiation (B) Natural convection (C) Forced convection (D) Conduction

Last Answer : (C) Forced convection

reduction in thermal resistance during heat transfer does not occur in the (A) Convection heat transfer by stirring the fluid and cleaning the heating surface (B) Conduction heat transfer by reduction in the material thickness and increase in the thermal conductivity (C) Radiation heat transfer by increasing the temperature and reducing the emissivity (D) None of these

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Last Answer : Option C

With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible. (A) Increases (B) Decreases (C) Remain same

Description : With increase in the mass velocity of the gas, the rate of drying during the constant rate period __________, if the conduction and radiation through the solid are negligible. (A) Increases (B) Decreases (C) Remain same

Last Answer : (A) Increases

Reynolds number of a fluid flowing in a circular pipe is 10,000. What will be the Reynolds number when the fluid velocity is decreased by 30% & the pipe diameter is increased by 30%? (A) 9,100 (B) 13,000 (C) 7,000 (D) 2,550

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Last Answer : (A) 9,100

Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is (A) Thin walled having the value of Ao Ai /< 2 (B) Thick walled (C) Having the value of Ao /Ai > 2 (D) Both (B) and (C)

Description : Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is (A) Thin walled having the value of Ao Ai /< 2 (B) Thick walled (C) Having the value of Ao /Ai > 2 (D) Both (B) and (C)

Last Answer : (A) Thin walled having the value of Ao Ai /< 2

Water hammer is caused, when water flowing in a pipe is suddenly brought to rest by closing the valve. The extent of pressure thus produced due to water hammer depends on the (A) Pipe length (B) Fluid velocity in the pipe (C) Time taken to close the valve (D) All (A), (B) and (C)

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Last Answer : (D) All (A), (B) and (C)

Shear stress in a fluid flowing in a round pipe (A) Varies parabolically across the cross-section(B) Remains constant over the cross-section(C) Is zero at the centre and varies linearly with the radius(D) Is zero at the wall and increases linearly to the centre

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Last Answer : (C) Is zero at the centre and varies linearly with the radius

The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is (A) Parabolic (B) Flat (C) Flat near the wall and parabolic in the middle (D) Parabolic near the wall and flat in the middle

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Last Answer : (D) Parabolic near the wall and flat in the middle

Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Schmidt (B) Sherwood (C) Peclet (D) Stanton

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Last Answer : (A) Schmidt

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

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

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 (B) Prandtl number in heat transfer is analogous to Schmidt number in mass transfer (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer (D) Reynolds number remains the same in both heat and mass transfer

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jH factor for heat transfer depends upon the __________ number. (A) Biot (B) Nusselt (C) Reynolds (D) Prandtl

Description : jH factor for heat transfer depends upon the __________ number. (A) Biot (B) Nusselt (C) Reynolds (D) Prandtl

Last Answer : (C) Reynolds