The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as

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The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as

A. Conduction

B. Free convection

C. Forced convection

D. Radiation

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An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be

A. 25 mm

B. 40 mm

C. 160 mm

D. 800 mm

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The logarithmic mean temperature difference (t_m) is given by (where Δt₁ and Δt₂ are temperature differences between the hot and cold fluids at entrance and exit)

A. t_m = (Δt₁ - Δt₂)/ log_e (Δt₁/Δt₂)

B. t_m = log_e (Δt₁/Δt₂)/ (Δt₁ - Δt₂)

C. t_m = t_m = (Δt₁ - Δt₂) log_e (Δt₁/Δt₂)

D. t_m = log_e (Δt₁ - Δt₂)/ Δt₁/Δt₂

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Fourier's law of heat conduction is valid for

A. One dimensional cases only

B. Two dimensional cases only

C. Three dimensional cases only

D. Regular surfaces having non-uniform temperature gradients

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Thermal conductivity of air with rise in temperature

A. Increases

B. Decreases

C. Remain constant

D. May increase or decrease depending on temperature

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The process of heat transfer from one particle of the body to another by the actual motion of the heated particles, is called

A. Conduction

B. Convection

C. Radiation

D. None of these

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The critical radius is the insulation radius at which the resistance to heat flow is

A. Maximum

B. Minimum

C. Zero

D. None of these

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The critical temperature is the temperature

A. Below which a gas does not obey gas laws

B. Above which a gas may explode

C. Below which a gas is always liquefied

D. Above which a gas will never liquefied

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Thermal conductivity of solid metals with rise in temperature normally

A. Increases

B. Decreases

C. Remain constant

D. May increase or decrease depending on temperature

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According of Kirchhoff's law

A. Radiant heat is proportional to fourth power of absolute temperature

B. Emissive power depends on temperature

C. Emissive power and absorptivity are constant for all bodies

D. Ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body.

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The ratio of surface convection resistance to the internal conduction resistance is known as

A. Grashoff number

B. Biot number

C. Stanton number

D. Prandtl number

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According to Prevost theory of heat exchange

A. It is impossible to transfer heat from low temperature source to t high temperature source

B. Heat transfer by radiation requires no medium

C. All bodies above absolute zero emit radiation

D. Heat transfer in most of the cases takes place by combination of conduction, convection and radiation

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The concept of overall coefficient of heat transfer is used in heat transfer problems of

A. Conduction

B. Convection

C. Radiation

D. Conduction and convection

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Reynolds number is the ratio of

A. Energy transferred by convection to that by conduction

B. Kinematic viscosity to thermal diffusivity

C. Inertia force to viscous force

D. None of the above

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The most commonly used method for the design of duct size is the

A. Velocity reduction method

B. Equal friction method

C. Static regains method

D. Dual or double method

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The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit

A. Temperature

B. Thickness

C. Area

D. Time

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The energy distribution of an ideal reflector at higher temperatures is largely in the range of

A. Shorter wavelength

B. Longer wavelength

C. Remain same at all wavelengths

D. Wavelength has nothing to do with it

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The unit of Stefan Boltzmann constant is

A. Watt/cm² °K

B. Watt/cm4 °K

C. Watt²/cm °K⁴

D. Watt/cm² °K⁴

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According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)

A. Pb = pa - pv

B. Pb = pa + pv

C. Pb = pa × pv

D. Pb = pa/pv

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The thermal diffusivities for solids are generally

A. Less than those for gases

B. Less than those for liquids

C. More than those for liquids and gases

D. More or less same as for liquids and gases

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In heat transfer, conductance equals conductivity (kcal/hr/sq.m/ °C/cm) divided by

A. Hr (time)

B. Sq. m (area)

C. °C (temperature)

D. K.cal (heat)

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The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as

A. Wien's law

B. Stefan's law

C. Kirchhoff's law

D. Planck's law

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LMTD in case of counter flow heat exchanger as compared to parallel flow heat exchanger is

A. Higher

B. Lower

C. Same

D. Depends on the area of heat exchanger

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Thermal conductivity of water at 20°C is of the order of

A. 0.1

B. 0.23

C. 0.42

D. 0.51

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The natural convection air cooled condensers are used in

A. Domestic refrigerators

B. Water coolers

C. Room air conditioners

D. All of these

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The heat transfer by conduction through a thick sphere is given by

A. Q = 2πkr₁ r₂ (T₁ - T₂)/ (r₂ - r₁)

B. Q = 4πkr₁ r₂ (T₁ - T₂)/ (r₂ - r₁)

C. Q = 6πkr₁ r₂ (T₁ - T₂)/ (r₂ - r₁)

D. Q = 8πkr₁ r₂ (T₁ - T₂)/ (r₂ - r₁)

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Sensible heat factor is given by (where S.H. = Sensible heat, and L.H. = Latent heat)

A. S.H/(S.H + L.H)

B. (S.H + L.H) /S.H

C. (L.H - S.H)/S.H

D. S.H/(L.H - S.H)

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If the temperature of a solid surface changes from 27°C to 627°C, then its emissive power changes in the ratio of

A. 6

B. 9

C. 27

D. 81

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The highest thermal diffusivity is of

A. Iron

B. Lead

C. Concrete

D. Wood

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Which of the following property of air does not increase with rise in temperature?

A. Thermal conductivity

B. Thermal diffusivity

C. Density

D. Dynamic viscosity

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Pick up the wrong case. Heat flowing from one side to other depends directly on

A. Face area

B. Time

C. Thickness

D. Temperature difference

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Accepted Answer

C. Forced convection

The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as

Correct Answer :

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Related Questions

An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be

The logarithmic mean temperature difference (t_m) is given by (where Δt₁ and Δt₂ are temperature differences between the hot and cold fluids at entrance and exit)

Fourier's law of heat conduction is valid for

Thermal conductivity of air with rise in temperature

The process of heat transfer from one particle of the body to another by the actual motion of the heated particles, is called

The critical radius is the insulation radius at which the resistance to heat flow is

The critical temperature is the temperature

Thermal conductivity of solid metals with rise in temperature normally

According of Kirchhoff's law

The ratio of surface convection resistance to the internal conduction resistance is known as

According to Prevost theory of heat exchange

The concept of overall coefficient of heat transfer is used in heat transfer problems of

Reynolds number is the ratio of

The most commonly used method for the design of duct size is the

The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit

The energy distribution of an ideal reflector at higher temperatures is largely in the range of

The unit of Stefan Boltzmann constant is

According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)

The thermal diffusivities for solids are generally

In heat transfer, conductance equals conductivity (kcal/hr/sq.m/ °C/cm) divided by

The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as

LMTD in case of counter flow heat exchanger as compared to parallel flow heat exchanger is

Thermal conductivity of water at 20°C is of the order of

The natural convection air cooled condensers are used in

The heat transfer by conduction through a thick sphere is given by

Sensible heat factor is given by (where S.H. = Sensible heat, and L.H. = Latent heat)

If the temperature of a solid surface changes from 27°C to 627°C, then its emissive power changes in the ratio of

The highest thermal diffusivity is of

Which of the following property of air does not increase with rise in temperature?

Pick up the wrong case. Heat flowing from one side to other depends directly on

Also checkout

The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as

Correct Answer :

Show all Heat & Mass Transfer MCQ

Related Questions

An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be

The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit)

Fourier's law of heat conduction is valid for

Thermal conductivity of air with rise in temperature

The process of heat transfer from one particle of the body to another by the actual motion of the heated particles, is called

The critical radius is the insulation radius at which the resistance to heat flow is

The critical temperature is the temperature

Thermal conductivity of solid metals with rise in temperature normally

According of Kirchhoff's law

The ratio of surface convection resistance to the internal conduction resistance is known as

According to Prevost theory of heat exchange

The concept of overall coefficient of heat transfer is used in heat transfer problems of

Reynolds number is the ratio of

The most commonly used method for the design of duct size is the

The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit

The energy distribution of an ideal reflector at higher temperatures is largely in the range of

The unit of Stefan Boltzmann constant is

According to Dalton's law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)

The thermal diffusivities for solids are generally

In heat transfer, conductance equals conductivity (kcal/hr/sq.m/ °C/cm) divided by

The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as

LMTD in case of counter flow heat exchanger as compared to parallel flow heat exchanger is

Thermal conductivity of water at 20°C is of the order of

The natural convection air cooled condensers are used in

The heat transfer by conduction through a thick sphere is given by

Sensible heat factor is given by (where S.H. = Sensible heat, and L.H. = Latent heat)

If the temperature of a solid surface changes from 27°C to 627°C, then its emissive power changes in the ratio of

The highest thermal diffusivity is of

Which of the following property of air does not increase with rise in temperature?

Pick up the wrong case. Heat flowing from one side to other depends directly on

Also checkout

The logarithmic mean temperature difference (t_m) is given by (where Δt₁ and Δt₂ are temperature differences between the hot and cold fluids at entrance and exit)