In a heat exchanger, one transfer unit means
In a heat exchanger, one transfer unit means
A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case,
A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case,
Radiator of an automobile engine is a __________ type of heat exchanger.
Radiator of an automobile engine is a __________ type of heat exchanger.
Conductance is given by(where, x = thickness, A = heat flow area, K = thermal conductivity.)
Conductance is given by(where, x = thickness, A = heat flow area, K = thermal conductivity.)
In the free convection regime of pool boiling, the heat flux is proportional to
In the free convection regime of pool boiling, the heat flux is proportional to
jH factor for heat transfer depends upon the __________ number.
jH factor for heat transfer depends upon the __________ number.
The equivalent diameter for pressure drop is __________ that for heat transfer.
The equivalent diameter for pressure drop is __________ that for heat transfer.
Solid angle subtended by the finite surface at the radiating element is
Solid angle subtended by the finite surface at the radiating element is
The most conducive surface for dropwise condensation to occur is the __________ surface.
The most conducive surface for dropwise condensation to occur is the __________ surface.
Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the
Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the
For what value of Prandtl number, St = f/2?
For what value of Prandtl number, St = f/2?
Economy of a multiple effect evaporator depends upon the
Economy of a multiple effect evaporator depends upon the
A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides
A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides
Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called
Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called
Unsteady state heat conduction occurs, when
Unsteady state heat conduction occurs, when
Which of the following is not concerned with the heat transfer?
Which of the following is not concerned with the heat transfer?
In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient
In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient
It is not preferable to use superheated steam in evaporators, because of its very
It is not preferable to use superheated steam in evaporators, because of its very
Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is
Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is
Electro-magnetic spectrum range, which is important for radiation varies from __________ microns.
Electro-magnetic spectrum range, which is important for radiation varies from __________ microns.
At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical?
At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical?
Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer can not take place
Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer can not take place
What is the emissivity of a black body?
What is the emissivity of a black body?
Which has the lowest Prandtl number?
Which has the lowest Prandtl number?
1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m² and the overall heat transfer co-efficient to the liquid is 1500 W/m².°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be
1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m² and the overall heat transfer co-efficient to the liquid is 1500 W/m².°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be
The average heat transfer co-efficient over the entire length of the plate (ha) and the local heat transfer co-efficient (hL), in case of heat transfer over a flat plate in lminar zone is related as
The average heat transfer co-efficient over the entire length of the plate (ha) and the local heat transfer co-efficient (hL), in case of heat transfer over a flat plate in lminar zone is related as
Stefen's block body radiation law can also be derived from __________ law.
Stefen's block body radiation law can also be derived from __________ law.
Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a droplet or a spherical particle to a surrounding stagnant film is
Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a droplet or a spherical particle to a surrounding stagnant film is
In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is
In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is
Prandtl and Reynold's analogies are identical for Prandtl number value of
Prandtl and Reynold's analogies are identical for Prandtl number value of
Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.
Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.
For a given ambient air temperature with increase in the thickness of insulation of a hot cylinderical pipe, the rate of heat loss from the surface would
For a given ambient air temperature with increase in the thickness of insulation of a hot cylinderical pipe, the rate of heat loss from the surface would
Vent pipes are provided in a condenser to
Vent pipes are provided in a condenser to
The interchange factor for radiation heat transfer from surface 'x' to surface 'y' in case of an infinite parallel planes with emis-sivities εx & εy is given by
The interchange factor for radiation heat transfer from surface 'x' to surface 'y' in case of an infinite parallel planes with emis-sivities εx & εy is given by
The overall resistance for heat transfer through a series of flat resistance, is the __________ of the resistances.
The overall resistance for heat transfer through a series of flat resistance, is the __________ of the resistances.
Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling?
Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling?
Pick out the wrong statement.
Pick out the wrong statement.
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids?
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids?
The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is
The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is
What is the geometric mean of two heat transfer areas A₁ and A₂ ?
What is the geometric mean of two heat transfer areas A₁ and A₂ ?
Pick out the wrong statement.
Pick out the wrong statement.
The non-dimensional temperature gradient in a liquid at the wall of a pipe is the
The non-dimensional temperature gradient in a liquid at the wall of a pipe is the
In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.
In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.
Absorptivity and refletivity of a perfect black body are respectively
Absorptivity and refletivity of a perfect black body are respectively
Baffle spacing
Baffle spacing
Pick out the wrong statement.
Pick out the wrong statement.
The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are
The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are
The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation.
The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation.
A BTU/hr.ft.2 °F is equal to
A BTU/hr.ft.2 °F is equal to
A body is called grey if the monochromatic emissivity of the body is
A body is called grey if the monochromatic emissivity of the body is
Pick out the wrong statement.
Pick out the wrong statement.
Heat exchangers operating, when the asymptotic range is reached,
Heat exchangers operating, when the asymptotic range is reached,
Choose the correct equation.
Choose the correct equation.
In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate.
In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate.
In a forward feed multiple effect evaporator, the pressure is
In a forward feed multiple effect evaporator, the pressure is
__________ paint has the maximum absorption coefficient.
__________ paint has the maximum absorption coefficient.
Heat transfer co-efficient (h1) for liquids increases with
Heat transfer co-efficient (h1) for liquids increases with
Agitated film evaporator is suitable for concentrating __________ liquids.
Agitated film evaporator is suitable for concentrating __________ liquids.
For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it
For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it
Shell side pressure drop in a shell and tube heat exchanger does not depend upon the
Shell side pressure drop in a shell and tube heat exchanger does not depend upon the
Correction is applied to LMTD for __________ flow.
Correction is applied to LMTD for __________ flow.
With increase in porosity, the thermal conductivity of a solid substance
With increase in porosity, the thermal conductivity of a solid substance
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid.
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid.
A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m².K. The Biot number is
A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m².K. The Biot number is
A graph between __________ is called Wilson plot.
A graph between __________ is called Wilson plot.
A dephlegmator is a
A dephlegmator is a
Natural convection is characterised by
Natural convection is characterised by
The separation of liquid droplets from the vapor is done by a/an __________ , in the evaporators.
The separation of liquid droplets from the vapor is done by a/an __________ , in the evaporators.
Pick out the wrong statement.
Pick out the wrong statement.
The film thickness for laminar film condensation on vertical surface __________ from top to bottom.
The film thickness for laminar film condensation on vertical surface __________ from top to bottom.
Heat flux, as defined in heat flow is analogous to __________ in electricity flow.
Heat flux, as defined in heat flow is analogous to __________ in electricity flow.
Fouling factor for a heat exchanger is given by (where, U₁ = heat transfer co-efficient of dirty surface U₂ = heat transfer co-efficient of clean surface)
Fouling factor for a heat exchanger is given by (where, U₁ = heat transfer co-efficient of dirty surface U₂ = heat transfer co-efficient of clean surface)
Baffles are provided in heat exchangers to increase the
Baffles are provided in heat exchangers to increase the
To reduce the tube side pressure drop for the same flow rate, the heat exchanger recomended is
To reduce the tube side pressure drop for the same flow rate, the heat exchanger recomended is
The range of electromagnetic spectrum important in heat transfer by radiation is __________ microns.
The range of electromagnetic spectrum important in heat transfer by radiation is __________ microns.
In natural convection heat transfer, the correlating parameter is the
In natural convection heat transfer, the correlating parameter is the
Trap is used to remove __________ from steam pipe lines.
Trap is used to remove __________ from steam pipe lines.
For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then
For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then
A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun?
A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun?
An ejector is used to
An ejector is used to
An insulator should have
An insulator should have
The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium. This is __________ law.
The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium. This is __________ law.
Vacuum is generally maintained in the vapour space of an evaporator mainly to
Vacuum is generally maintained in the vapour space of an evaporator mainly to
Nusselt number for full developed, laminar, constant property flow in a pipe at uniform heat flux is
Nusselt number for full developed, laminar, constant property flow in a pipe at uniform heat flux is
'Duhring's plot' is of use in
'Duhring's plot' is of use in
A 2-4 heat exchanger involves
A 2-4 heat exchanger involves
At constant temperature, the thermal conductivities of gases __________ with rise in pressure.
At constant temperature, the thermal conductivities of gases __________ with rise in pressure.
A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?
A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?
__________ chart is known as transient heat conduction chart.
__________ chart is known as transient heat conduction chart.
Prandtl and Reynolds analogy are same, when Prandtl number is
Prandtl and Reynolds analogy are same, when Prandtl number is
Stefan-Boltzman law applies to __________ body.
Stefan-Boltzman law applies to __________ body.
A black body does not __________ radiation.
A black body does not __________ radiation.
Dietus-Boelter equation cannot be used for molten metals mainly due to its very low
Dietus-Boelter equation cannot be used for molten metals mainly due to its very low
The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law.
The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoffs law.
Rate of crystallisation does not depend upon the
Rate of crystallisation does not depend upon the
Film boiling is usually not desired in commercial equipments, because
Film boiling is usually not desired in commercial equipments, because
What is the absorptivity of a black body?
What is the absorptivity of a black body?
Calburn analogy is applicable for the value of Prandtl number from
Calburn analogy is applicable for the value of Prandtl number from
Heat produced when a steady state current, I passes through an electrical conductor having resistance, 'R' is
Heat produced when a steady state current, I passes through an electrical conductor having resistance, 'R' is
Which of the following has the lowest Prandtl number?
Which of the following has the lowest Prandtl number?
