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

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
by

1 Answer

Answer :

(C) Radiation becomes important
by

Related questions

Upto the critical radius of insulation, added insulation, will (A) Increase the heat loss (B) Decrease heat loss and will have no effect beyond that (C) Decrease heat flux (D) Reduce convection heat loss compared to conduction heat less

Description : Upto the critical radius of insulation, added insulation, will (A) Increase the heat loss (B) Decrease heat loss and will have no effect beyond that (C) Decrease heat flux (D) Reduce convection heat loss compared to conduction heat less

Last Answer : Option B

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

In sub-cooled boiling, (A) Temperature of the heating surface is less than the boiling point of the liquid (B) Temperature of the heating surface is more than the boiling point of the liquid (C) Bubbles from heating surface are absorbed by the mass of the liquid (D) Very large vapour space is necessary

Description : In sub-cooled boiling, (A) Temperature of the heating surface is less than the boiling point of the liquid (B) Temperature of the heating surface is more than the boiling point of the liquid (C) ... from heating surface are absorbed by the mass of the liquid (D) Very large vapour space is necessary

Last Answer : (B) Temperature of the heating surface is more than the boiling point of the liquid

Gibbs phase rule finds application, when heat transfer occurs by (A) Conduction (B) Convection (C) Radiation (D) Condensation

Description : Gibbs phase rule finds application, when heat transfer occurs by (A) Conduction (B) Convection (C) Radiation (D) Condensation

Last Answer : (D) Condensation

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

Mode of heat transfer involved in the cooling of air cooled internal combustion engine is (A) Conduction(B) Natural convection(C) Forced convection(D) None of these

Description : Mode of heat transfer involved in the cooling of air cooled internal combustion engine is (A) Conduction (B) Natural convection (C) Forced convection (D) None of these

Last Answer : (B) Natural convection

__________________ is a liquid at the saturations which has temperature equal to the boiling point corresponding to the existing pressure.  a. Saturation Temperature  b. Sub cooled Liquid  c. Compressed Liquid  d. Saturated Liquid

Description : __________________ is a liquid at the saturations which has temperature equal to the boiling point corresponding to the existing pressure.  a. Saturation Temperature  b. Sub cooled Liquid  c. Compressed Liquid  d. Saturated Liquid

Last Answer : Saturated Liquid

In which mode of heat transfer, the Biot number is important? (A) Transient heat conduction (B) Natural convection (C) Forced convection (D) Radiation

Description : In which mode of heat transfer, the Biot number is important? (A) Transient heat conduction (B) Natural convection (C) Forced convection (D) Radiation

Last Answer : (A) Transient heat conduction

View factor is important in heat transfer by (A) Steady state conduction (B) Natural convection (C) Forced convection (D) Radiation

Description : View factor is important in heat transfer by (A) Steady state conduction (B) Natural convection (C) Forced convection (D) Radiation

Last Answer : (D) Radiation

In furnaces operating at very high temperature (say) 1250°C, e.g. soaking pit), the maximum heat transfer takes place by (A) Conduction (B) Convection (C) Radiation (D) Cannot be predicted

Description : In furnaces operating at very high temperature (say) 1250°C, e.g. soaking pit), the maximum heat transfer takes place by (A) Conduction (B) Convection (C) Radiation (D) Cannot be predicted

Last Answer : (C) Radiation

Maximum heat transfer in high temperature furnaces is by (A) Conduction (B) Convection (C) Radiation (D) Either (A), (B) or (C); depends on the type of furnace

Description : Maximum heat transfer in high temperature furnaces is by (A) Conduction (B) Convection (C) Radiation (D) Either (A), (B) or (C); depends on the type of furnace

Last Answer : (C) Radiation

In a furnace with heating element temperature at 1700°C, the dominant mechanism of heat transfer will be (A) Conduction (B) Radiation (C) Natural convection (D) Forced convection

Description : In a furnace with heating element temperature at 1700°C, the dominant mechanism of heat transfer will be (A) Conduction (B) Radiation (C) Natural convection (D) Forced convection

Last Answer : (B) Radiation

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

Description : 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 ... Radiation heat transfer by increasing the temperature and reducing the emissivity (D) None of these

Last Answer : Option C

Heat is transmitted from higher temperature to lower temperature through the actual motion of the molecules in – (1) Conduction (2) Convection (3) Radiation (4) Both conduction and convection

Description : Heat is transmitted from higher temperature to lower temperature through the actual motion of the molecules in – (1) Conduction (2) Convection (3) Radiation (4) Both conduction and convection

Last Answer : (2) Convection Explanation: The process of heat transfer from one place to an-other place without the movement of particles is called conduction Example: Heat transfer through Metal rods. On the ... heated particles of the substance. The fluids (liquids and gases) are heated by this process.

Heat is transmitted from higher temperature to lower temperature through the actual motion of the molecules in - (1) Conduction (2) Convection (3) Radiation (4) Both conduction and convection

Description : Heat is transmitted from higher temperature to lower temperature through the actual motion of the molecules in - (1) Conduction (2) Convection (3) Radiation (4) Both conduction and convection

Last Answer : (2) Convection Explanation: The process of heat transfer from one place to another place without the movement of particles is called conduction,

The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc. (a) conduction (b) convection (c) radiation (d) any ofthe above

Description : The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc. (a) conduction (b) convection (c) radiation (d) any ofthe above

Last Answer : (c) radiation

Heat is transmitted from higher temperature to lower temperature through the actual motion of the molecules in (1) Conduction (2) Convection (3) Radiation (4) Both conduction and convection

Description : Heat is transmitted from higher temperature to lower temperature through the actual motion of the molecules in (1) Conduction (2) Convection (3) Radiation (4) Both conduction and convection

Last Answer : Convection

Choose the wrong statement (a) Temperature of medium being cooled must be below that of the evaporator (b) Refrigerant leaves the condenser as liquid (c) All solar thermally operated absorption systems are capable only of intermittent operation (d) frost on evaporator reduces heat transfer

Description : Choose the wrong statement (a) Temperature of medium being cooled must be below that of the evaporator (b) Refrigerant leaves the condenser as liquid (c) All solar thermally operated absorption systems are capable only of intermittent operation (d) frost on evaporator reduces heat transfer

Last Answer : Ans: a

A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time (A) t = 283 s (B) t = 356 s (C) t = 400 s (D) t = 800 s

Description : A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The ... = 283 s (B) t = 356 s (C) t = 400 s (D) t = 800 s

Last Answer : (D) t = 800 s

Fourier's law applies to the heat transfer by (A) Convection (B) Radiation (C) Conduction (D) All (A), (B) & (C)

Description : Fourier's law applies to the heat transfer by (A) Convection (B) Radiation (C) Conduction (D) All (A), (B) & (C)

Last Answer : (C) Conduction

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

When warm and cold liquids are mixed, the heat transfer is mainly by (A) Conduction (B) Convection (C) Radiation (D) Both (A) & (C

Description : When warm and cold liquids are mixed, the heat transfer is mainly by (A) Conduction (B) Convection (C) Radiation (D) Both (A) & (C

Last Answer : (B) Convection

If heat transfer rate varies with the time, it is termed as (A) Forced convection (B) Steady state conduction (C) Monochromatic radiation (D) None of these

Description : If heat transfer rate varies with the time, it is termed as (A) Forced convection (B) Steady state conduction (C) Monochromatic radiation (D) None of these

Last Answer : (D) None of these

Loss of heat from untagged steam pipe to the ambient air is by (A) Conduction (B) Convection (C) Radiation (D) All (A), (B) & (C)

Description : Loss of heat from untagged steam pipe to the ambient air is by (A) Conduction (B) Convection (C) Radiation (D) All (A), (B) & (C)

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

Heat transfer by __________ may not necessarily require the presence of a medium. (A) Conduction (B) Natural convection (C) Forced convection (D) Radiation

Description : Heat transfer by __________ may not necessarily require the presence of a medium. (A) Conduction (B) Natural convection (C) Forced convection (D) Radiation

Last Answer : (D) Radiation

In reverberatory furnace, charge is heated mainly by (A) Conduction (B) Natural convection (C) Radiation of heat from the roof of the combustion chamber (D) None of these

Description : In reverberatory furnace, charge is heated mainly by (A) Conduction (B) Natural convection (C) Radiation of heat from the roof of the combustion chamber (D) None of these

Last Answer : (C) Radiation of heat from the roof of the combustion chamber

In salt bath furnace, heat is transferred to the charge mainly by (A) Conduction (B) Convection (C) Radiation (D) None of these

Description : In salt bath furnace, heat is transferred to the charge mainly by (A) Conduction (B) Convection (C) Radiation (D) None of these

Last Answer : (A) Conduction

Heat transfer by __________ is almost absent in case of fluidised bed drying operation. (A) Radiation (B) Conduction (C) Convection (D) Both (B) & (C)

Description : Heat transfer by __________ is almost absent in case of fluidised bed drying operation. (A) Radiation (B) Conduction (C) Convection (D) Both (B) & (C)

Last Answer : A) Radiation

Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by (A) Conduction (B) Convection (C) Radiation (D) Both 'a' & 'b'

Description : Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by (A) Conduction (B) Convection (C) Radiation (D) Both 'a' & 'b'

Last Answer : Option C

In the free convection regime of pool boiling, the heat flux is proportional to (A) Δt 1/2 (B) Δt 2 (C) Δt 5/4 (D) Δt

Description : In the free convection regime of pool boiling, the heat flux is proportional to (A) Δt 1/2 (B) Δt 2 (C) Δt 5/4 (D) Δt

Last Answer : (C) Δt 5/4

_________ is the transition of a given substance from the solid to the gas phase with no intermediate liquid stage.  a. Convection  b. Conduction  c. Radiation  d. Sublimation

Description : _________ is the transition of a given substance from the solid to the gas phase with no intermediate liquid stage.  a. Convection  b. Conduction  c. Radiation  d. Sublimation

Last Answer : Sublimation

Pick out the wrong statement. (A) The value of hydrostatic head increases with increase in vacuum in the effect in a multiple effect evaporator system (B) Entering velocity of the liquid in the tubes of natural circulation evaporators is in the range of 0.3 to 0.9 metre/second (C) Duhring's plot is used for calculating the concentration of solution (D) In a multiple effect evaporation system, the number of effects is limited by the total boiling point rise

Description : Pick out the wrong statement. (A) The value of hydrostatic head increases with increase in vacuum in the effect in a multiple effect evaporator system (B) Entering velocity of the liquid in ... a multiple effect evaporation system, the number of effects is limited by the total boiling point rise

Last Answer : (C) Duhring's plot is used for calculating the concentration of solution

Pick out the correct statement. (A) 1 kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F (B) In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity (C) In unsteady state heat conduction, heat flows in the direction of temperature rise (D) In heat transfer by forced convection, Grashoff number is very important

Description : Pick out the correct statement. (A) 1 kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F (B) In steady state heat conduction, the only property of the substance which determines the ... in the direction of temperature rise (D) In heat transfer by forced convection, Grashoff number is very important

Last Answer : (B) In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity

By which of the following methods could a cup of hot coffee lose heat if placed on a metal table in a room? (a) Conduction and radiation (b) Conduction and convection (c) Convection and radiation (d) Conduction, convection, radiation and evaporation

Description : By which of the following methods could a cup of hot coffee lose heat if placed on a metal table in a room? (a) Conduction and radiation (b) Conduction and convection (c) Convection and radiation (d) Conduction, convection, radiation and evaporation

Last Answer : Ans:(d)

By what process is heat transmitted from the filament of an evacuated electric bulb to the glass? (a) Conduction (b) Convection (c) Radiation (d) Heat cannot be transmitted through vacuum

Description : By what process is heat transmitted from the filament of an evacuated electric bulb to the glass? (a) Conduction (b) Convection (c) Radiation (d) Heat cannot be transmitted through vacuum

Last Answer : Ans:(c)

Even after sunset, the air near the Earth's surface continue to receive heat due to – (1) Insolation (2) Terrestrial Radiation (3) Conduction (4) Convection

Description : Even after sunset, the air near the Earth's surface continue to receive heat due to – (1) Insolation (2) Terrestrial Radiation (3) Conduction (4) Convection

Last Answer : (2) Terrestrial Radiation Explanation: Even after the sunset when the sun goes down, the incoming radiation from the sun stops, but there is still a lot of radiation that has been absorbed ... i.e. terrestrial radiation heats up the atmosphere more than the incoming solar radiation i.e. insolation

Transfer of heat energy from a heater coil to the cooking vessel takes place through the process of- (1) Convection only (2) Conduction and convection only (3) Radiation and convection only (4) Convection, conduction and radiation

Description : Transfer of heat energy from a heater coil to the cooking vessel takes place through the process of- (1) Convection only (2) Conduction and convection only (3) Radiation and convection only (4) Convection, conduction and radiation

Last Answer : (3) Radiation and convection only Explanation: Conduction is the transfer of heat energy by direct contact, convection is the movement of heat by actual motion of matter; radiation is the transfer of energy with the help of electromagnetic waves.

Heat from the sun reaches earth by the process of – (1) Conduction (2) Convection (3) Radiation (4) All of the above

Description : Heat from the sun reaches earth by the process of – (1) Conduction (2) Convection (3) Radiation (4) All of the above

Last Answer : (3) Radiation Explanation: In physics, radiation is a process in which energetic particles or energetic waves travel through vacuum, or through mattercontaining media that are not required for their propagation.

Suns heat reaches us by – (1) Conduction (2) Convection (3) Radiation (4) Reflection

Description : Suns heat reaches us by – (1) Conduction (2) Convection (3) Radiation (4) Reflection

Last Answer : (3) Radiation Explanation: Radiation is a process in which energetic particles or energetic waves travel through vacuum, or through matter-containing media that are not required for their propagation. The sun' ... frequencies), but those from the sun are mainly infra-red, visible, and ultra-violet.

Heat from the Sun reaches the Earth by (1) Reflection (2) Conduction (3) Radiation (4) Convection

Description : Heat from the Sun reaches the Earth by (1) Reflection (2) Conduction (3) Radiation (4) Convection

Last Answer : (3) Radiation Explanation: The radiation (light, heat, etc.) travels through the intervening 150,000,000 kilometers in 8 minutes. Radiation is a process in which energetic particles or energetic waves ... waves or sound waves, are usually not considered to be forms of "radiation" in this sense.

A process by which heat is transferred through a material without a bulk movement of the material.  a. Convection  b. Conduction  c. Radiation  d. Emission

Description : A process by which heat is transferred through a material without a bulk movement of the material.  a. Convection  b. Conduction  c. Radiation  d. Emission

Last Answer : Conduction

A process in which heat energy is transferred by the flow of fluid.  a. Convection  b. Conduction  c. Radiation  d. Sublimation

Description : A process in which heat energy is transferred by the flow of fluid.  a. Convection  b. Conduction  c. Radiation  d. Sublimation

Last Answer : Convection

How is heat transferred?  A. By conduction  B. By convection  C. By radiation  D. All of the above

Description : How is heat transferred?  A. By conduction  B. By convection  C. By radiation  D. All of the above

Last Answer : All of the above

____ heating means that the circulation of currents in one region inside a can distributes the heat to another. a. Conduction c. Convection b. Radiation d. Slow

Description : ____ heating means that the circulation of currents in one region inside a can distributes the heat to another. a. Conduction c. Convection b. Radiation d. Slow

Last Answer : c. Convection

____ is the transfer of heat from one particle to another by contact. a. Conduction c. Radiation b. Convection d. Combustion

Description : ____ is the transfer of heat from one particle to another by contact. a. Conduction c. Radiation b. Convection d. Combustion

Last Answer : a. Conduction

The mcrease in heat dissipation by air blasts is due to increase in (a) conduction (b) convection (e) radiation (d) any ofthe above

Description : The mcrease in heat dissipation by air blasts is due to increase in (a) conduction (b) convection (e) radiation (d) any ofthe above

Last Answer : (b) convection

The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ? (a) Conduction (b) Convection (c) Radiation (d) All ofthe above

Description : The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ? (a) Conduction (b) Convection (c) Radiation (d) All ofthe above

Last Answer : (d) All ofthe above

In EXTRA-TERRESTRIAL SPACE, heat is transferred by: w) conduction x) convection y) conduction and convention z) radiation

Description : In EXTRA-TERRESTRIAL SPACE, heat is transferred by: w) conduction x) convection y) conduction and convention z) radiation

Last Answer : ANSWER: Z -- RADIATION

Heat from the sun reaches the Earth by: w) conduction x) convection y) radiation z) none of the above

Description : Heat from the sun reaches the Earth by: w) conduction x) convection y) radiation z) none of the above

Last Answer : ANSWER: Y -- RADIATION

Heat is transferred from the sun to the earth primarily by: w) conduction x) convection y) radiation z) condensation

Description : Heat is transferred from the sun to the earth primarily by: w) conduction x) convection y) radiation z) condensation 

Last Answer : ANSWER: Y -- RADIATION