Thermal diffusivity of a material
Thermal diffusivity of a material
Reynold's analogy states that
Reynold's analogy states that
The unit of conductance in SI unit is
The unit of conductance in SI unit is
Radiation heat transfer rates does not depend upon the
Radiation heat transfer rates does not depend upon the
A __________ evaporator employs an annular downtake.
A __________ evaporator employs an annular downtake.
In a shell and tube heat exchanger,
In a shell and tube heat exchanger,
Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
Which of the following is unimportant in forced convection?
Which of the following is unimportant in forced convection?
The energy radiated from a surface Q at absolute temperature T is related as
The energy radiated from a surface Q at absolute temperature T is related as
Duhring rule is important in solving problems on
Duhring rule is important in solving problems on
For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is
For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is
Sensible heat of hot industrial flue gases can not be recovered by a/an
Sensible heat of hot industrial flue gases can not be recovered by a/an
Open pan evaporators are preferred to be used, when the solution to be concentrated is
Open pan evaporators are preferred to be used, when the solution to be concentrated is
Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping
Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping
For evaporation of viscous solution in a multiple effect evaporator, the prefered feeding scheme is
For evaporation of viscous solution in a multiple effect evaporator, the prefered feeding scheme is
Pick out the wrong statement:
Pick out the wrong statement:
Double pipe heat exchangers are preferably useful, when
Double pipe heat exchangers are preferably useful, when
Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by
Heat transfer efficiency leading of energy conservation in a heat exchanger can be achieved by
A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is
A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is
Kirchoff s law applies to __________ radiation.
Kirchoff s law applies to __________ radiation.
Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be
Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be
Fourier's law applies to the heat transfer by
Fourier's law applies to the heat transfer by
When warm and cold liquids are mixed, the heat transfer is mainly by
When warm and cold liquids are mixed, the heat transfer is mainly by
For a multipass shell and tube heat exchanger, the LMTD correction factor is always
For a multipass shell and tube heat exchanger, the LMTD correction factor is always
For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it
Planck's distribution law is valid for __________ bodies.
Planck's distribution law is valid for __________ bodies.
Peclet number (Pe) is given by
Peclet number (Pe) is given by
Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid
Dietus-Boelter equation used for the determination of heat transfer co-efficient is valid
Pick out the wrong statement.
Pick out the wrong statement.
Small scale evaporation is done in a
Small scale evaporation is done in a
Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is
Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally
For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally
Steam trap is used to
Steam trap is used to
(Cp . μ)/K is termed as the __________ number.
(Cp . μ)/K is termed as the __________ number.
For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area
For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area
In a boiling curve, the peak heat flux is called the __________ point.
In a boiling curve, the peak heat flux is called the __________ point.
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is
In case of a vertical tube evaporator, with increase in the liquor level, the
In case of a vertical tube evaporator, with increase in the liquor level, the
A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when
A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when
Heat flux is the time rate of heat transfer per unit
Heat flux is the time rate of heat transfer per unit
Forced circulation evaporators are normally used for concentrating liquids having
Forced circulation evaporators are normally used for concentrating liquids having
Leidenfrost point is a term concerned with the
Leidenfrost point is a term concerned with the
Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger?
Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger?
Pick out the wrong statement.
Pick out the wrong statement.
Maximum heat transfer rate is obtained in __________ flow.
Maximum heat transfer rate is obtained in __________ flow.
The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid
The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid
Water is normally used as a coolant in the heat exchange equipments mainly because ofits
Water is normally used as a coolant in the heat exchange equipments mainly because ofits
Fourier's law of heat conduction applies to __________ surfaces.
Fourier's law of heat conduction applies to __________ surfaces.
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer
For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number)
For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number)
The steam ejector is used to
The steam ejector is used to
jH factor for heat transfer is not a function of the __________ number.
jH factor for heat transfer is not a function of the __________ number.
LMTD correction factor which is to be applied for a cross-flow heat exchanger increases with increase in the number of shell passes. Its value for a single pass cross flow heat exchanger is
LMTD correction factor which is to be applied for a cross-flow heat exchanger increases with increase in the number of shell passes. Its value for a single pass cross flow heat exchanger is
An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a
An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a
Steam is routed through the tube in case of a __________ evaporator.
Steam is routed through the tube in case of a __________ evaporator.
If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law.
If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law.
The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K₀ + at. where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be
The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K₀ + at. where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be
Maximum heat transfer rate is achieved in __________ flow.
Maximum heat transfer rate is achieved in __________ flow.
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.
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.
(NRe.NPr)(D/L) is called the __________ number
(NRe.NPr)(D/L) is called the __________ number
Prandtl number is the reciprocal of
Prandtl number is the reciprocal of
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
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
The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)
The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)
Intermittant tube cleaning is possible to be done in case of a __________ evaporator.
Intermittant tube cleaning is possible to be done in case of a __________ evaporator.
Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is
Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is
Nusselt number (for forced convection heat transfer) is a function of the __________ number.
Nusselt number (for forced convection heat transfer) is a function of the __________ number.
For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are
For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are
For hot feed, forward feeding as compared to backward feeding results in __________ economy.
For hot feed, forward feeding as compared to backward feeding results in __________ economy.
In which mode of heat transfer, the Biot number is important?
In which mode of heat transfer, the Biot number is important?
A multiple effect evaporator as compared to a single effect evaporator of the same capacity has
A multiple effect evaporator as compared to a single effect evaporator of the same capacity has
Prandtl number is the ratio of
Prandtl number is the ratio of
With increase in temperature, the total emissivity of conductors
With increase in temperature, the total emissivity of conductors
1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is
1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is
The purpose of providing bleed points in the evaporator is to
The purpose of providing bleed points in the evaporator is to
In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.
In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.
One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to
One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to
The critical radius 'r' of insulation on a pipe is given by
The critical radius 'r' of insulation on a pipe is given by
With the increase of temperature, the Col-burn jH factor
With the increase of temperature, the Col-burn jH factor
Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the
Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the
During crystallisation, formation of crystal can occur in __________ solution only.
During crystallisation, formation of crystal can occur in __________ solution only.
The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m².K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m².K. The overall heat transfer co-efficient at this time is
The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m².K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m².K. The overall heat transfer co-efficient at this time is
In an interphase heat transfer process, the equilibrium state corresponds to equality of temperature in the two phases, while the condition for equilibrium in an interphase mass transfer process is equality of
In an interphase heat transfer process, the equilibrium state corresponds to equality of temperature in the two phases, while the condition for equilibrium in an interphase mass transfer process is equality of
A perfect black body is a perfect __________ of radiation.
A perfect black body is a perfect __________ of radiation.
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface?
Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface?
Pick out the correct equation.
Pick out the correct equation.
Heat sensitive materials can be concentrated in an evaporator employing
Heat sensitive materials can be concentrated in an evaporator employing
Analogy between mass and heat transfer is not applicable in case of
Analogy between mass and heat transfer is not applicable in case of
For a perfectly transparent surface (like gases), the
For a perfectly transparent surface (like gases), the
The thermal boundary layer at NPr > 1
The thermal boundary layer at NPr > 1
Viscous & heat sensitive liquids are concentrated in __________ evaporators.
Viscous & heat sensitive liquids are concentrated in __________ evaporators.
A sphere of radius 'R₁' is enclosed in a sphere of radius 'R₂'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is
A sphere of radius 'R₁' is enclosed in a sphere of radius 'R₂'. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is
Heat transfer rate per unit area is called
Heat transfer rate per unit area is called
The units of resistance to heat transfer is
The units of resistance to heat transfer is
In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.
In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid.
Corrosiveness of steam condensate is due to the presence of
Corrosiveness of steam condensate is due to the presence of
Nusselt number is the ratio of the temperature gradient at the wall to
Nusselt number is the ratio of the temperature gradient at the wall to
At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical?
At what value of Prandtl number, the hydrodynamic and thermal boundary layers are identical?
The thickness of condensate layer in filmwise condensation depends on the
The thickness of condensate layer in filmwise condensation depends on the
Pick out the wrong statement.
Pick out the wrong statement.
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)
In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)
