According to Newton's law of cooling, the heat transfer from a hot body to a cold body is

Question

According to Newton's law of cooling, the heat transfer from a hot body to a cold body is

A. Directly proportional to the surface area

B. Directly proportional to the difference of temperatures between the two bodies

C. Either (A) or (B)

D. Both (A) and (B)

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In case of liquids and gases, the heat transfer takes place according to

A. Conduction

B. Convection

C. Radiation

D. None of these

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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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The unit of overall coefficient of heat transfer is

A. W/m²K

B. W/m²

C. W/mK

D. W/m

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A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h₁, h₂ and h₃ respectively. The average heat transfer coefficient for the cube is

A. h₁ + h₂ + h₃

B. (h₁.h₂.h₃)1/3

C. 1/h₁ + 1/h₂ + 1/h₃

D. None of these

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The amount of radiation mainly depends on

A. Nature of body

B. Temperature of body

C. Type of surface of body

D. All of the above

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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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Total heat is the heat required to

A. Change vapour into liquid

B. Change liquid into vapour

C. Increase the temperature of a liquid or vapour

D. Convert water into steam and superheat it

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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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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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A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as

A. A.C_min/U

B. U/A.C_min

C. A.U.C_min

D. A.U/C_min

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Emissivity of a white polished body in comparison to a black body is

A. Higher

B. Lower

C. Same

D. Depends upon the shape of body

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The expression Q = ρ AT⁴ is called

A. Fourier equation

B. Stefan-Boltzmann equation

C. Newton Reichmann equation

D. Joseph-Stefan equation

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A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100° C and leaves at 60° C. A cold fluid enters the heat exchanger at 40° C. The mean temperature difference between the two fluids is

A. 20°C

B. 40°C

C. 60°C

D. 66.7°C

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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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Log mean temperature difference in case of counter flow compared to parallel flow will be

A. Same

B. More

C. Less

D. Depends on other factors

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A non-dimensional number generally associated with natural convection heat transfer is

A. Grashoff number

B. Nusselt number

C. Weber number

D. Prandtl number

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Unit of thermal diffusivity is

A. m²/hr

B. m²/hr °C

C. kcal/m² hr

D. kcal/m. hr °C

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Depending on the radiating properties, a body will be black when

A. P = 0, x = 0 and a = 1

B. P= 1, T = 0 and a = 0

C. P = 0, x = 1 and a = 0

D. X = 0, a + p = 0 Where a = absorptivity, p = reflectivity, X = transmissivity.

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Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in

A. Electric heater

B. Steam condenser

C. Boiler

D. Refrigerator condenser coils

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Stefan Boltzmann law is applicable for heat transfer by

A. Conduction

B. Convection

C. Radiation

D. Conduction and radiation combined

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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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Depending on the radiating properties, a body will be opaque when

A. P = 0, x = 0 and a = 1

B. P=1, x = 0 and a = 0

C. P = 0, x = 1 and a = 0

D. X = 0, a + p = 1 Where a = absorptivity, p = reflectivity, X = transmissivity.

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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 unit of overall coefficient of heat transfer is

A. kcal/m²

B. kcal/hr °C

C. kcal/m² hr °C

D. kcal/m hr °C

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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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The heat of sun reaches to us according to

A. Conduction

B. Convection

C. Radiation

D. None of these

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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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In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by

A. Convection

B. Radiation

C. Conduction

D. Both convection and conduction

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Fourier's law of heat conduction gives the heat flow for

A. Irregular surfaces

B. Nonuniform temperature surfaces

C. One dimensional cases only

D. Two dimensional cases only

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Sensible heat is the heat required to

A. Change vapour into liquid

B. Change liquid into vapour

C. Increase the temperature of a liquid of vapour

D. Convert water into steam and superheat it

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Accepted Answer

D. Both (A) and (B)

According to Newton's law of cooling, the heat transfer from a hot body to a cold body is

Correct Answer :

Show all Heat & Mass Transfer MCQ

Related Questions

In case of liquids and gases, the heat transfer takes place according to

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

The unit of overall coefficient of heat transfer is

A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h₁, h₂ and h₃ respectively. The average heat transfer coefficient for the cube is

The amount of radiation mainly depends on

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

Total heat is the heat required to

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

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 heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as

Emissivity of a white polished body in comparison to a black body is

The expression Q = ρ AT⁴ is called

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

Log mean temperature difference in case of counter flow compared to parallel flow will be

A non-dimensional number generally associated with natural convection heat transfer is

Unit of thermal diffusivity is

Depending on the radiating properties, a body will be black when

Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in

Stefan Boltzmann law is applicable for heat transfer by

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

Depending on the radiating properties, a body will be opaque when

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 unit of overall coefficient of heat transfer is

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

The heat of sun reaches to us according to

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

In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by

Fourier's law of heat conduction gives the heat flow for

Sensible heat is the heat required to

Also checkout

According to Newton's law of cooling, the heat transfer from a hot body to a cold body is

Correct Answer :

Show all Heat & Mass Transfer MCQ

Related Questions

In case of liquids and gases, the heat transfer takes place according to

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

The unit of overall coefficient of heat transfer is

A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h₁, h₂ and h₃ respectively. The average heat transfer coefficient for the cube is

The amount of radiation mainly depends on

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

Total heat is the heat required to

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

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 heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as

Emissivity of a white polished body in comparison to a black body is

The expression Q = ρ AT4 is called

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

Log mean temperature difference in case of counter flow compared to parallel flow will be

A non-dimensional number generally associated with natural convection heat transfer is

Unit of thermal diffusivity is

Depending on the radiating properties, a body will be black when

Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in

Stefan Boltzmann law is applicable for heat transfer by

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

Depending on the radiating properties, a body will be opaque when

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 unit of overall coefficient of heat transfer is

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

The heat of sun reaches to us according to

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

In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by

Fourier's law of heat conduction gives the heat flow for

Sensible heat is the heat required to

Also checkout

The expression Q = ρ AT⁴ is called