Tube pitch is the __________ of tube diameters and the clearances.
Tube pitch is the __________ of tube diameters and the clearances.
Loss of heat from untagged steam pipe to the ambient air is by
Loss of heat from untagged steam pipe to the ambient air is by
A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.
A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.
Pick out the wrong statement.
Pick out the wrong statement.
Overall heat transfer co-efficient of a particular tube is U₁. If the same tube with some dirt deposited on either side has coefficient U₂, then
Overall heat transfer co-efficient of a particular tube is U₁. If the same tube with some dirt deposited on either side has coefficient U₂, then
According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor)
According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor)
Mode of heat transfer involved in the cooling of air cooled internal combustion engine is
Mode of heat transfer involved in the cooling of air cooled internal combustion engine is
Multiple effect evaporators ar used to
Multiple effect evaporators ar used to
In a multiple effect evaporator, the effect of boiling point elevation is to
In a multiple effect evaporator, the effect of boiling point elevation is to
In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)
In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)
Pick out the wrong statement.
Pick out the wrong statement.
The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid.
The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid.
Heat transfer rate described by Fourier's law will decrease, if the __________ increases.
Heat transfer rate described by Fourier's law will decrease, if the __________ increases.
In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.
In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.
Three material A, B and C of equal thick-nes and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of __________ °C.
Three material A, B and C of equal thick-nes and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of __________ °C.
Terminal point temperature differences between fluids in case of a heat exchanger is termed as
Terminal point temperature differences between fluids in case of a heat exchanger is termed as
Crystal size in a continuous crystalliser depends upon the
Crystal size in a continuous crystalliser depends upon the
If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is
If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is
Which of the following is correct?
Which of the following is correct?
The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is __________ compared to the same size pipes without fins.
The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is __________ compared to the same size pipes without fins.
LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.
LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.
The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is
The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is
The main function of baffles provided in a shell and tube heat exchanger is to
The main function of baffles provided in a shell and tube heat exchanger is to
Pick out the wrong statement.
Pick out the wrong statement.
In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell)
In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell)
With increase in temperature, the thermal conductivity of steel
With increase in temperature, the thermal conductivity of steel
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m² .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m² .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the
A diathermaneous substance __________ the thermal radiation completely.
A diathermaneous substance __________ the thermal radiation completely.
The equation, (NSt x N2/3Pr) = f/2, is the __________ analogy.
The equation, (NSt x N2/3Pr) = f/2, is the __________ analogy.
Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow. )
Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow. )
What is the thermal conductivity of a perfect heat insulator?
What is the thermal conductivity of a perfect heat insulator?
(NGr x NPr) is called the __________ number.
(NGr x NPr) is called the __________ number.
In a 1-1 cocurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is
In a 1-1 cocurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is
The ratio of kinematic viscosity to thermal diffusivity is called the __________ number.
The ratio of kinematic viscosity to thermal diffusivity is called the __________ number.
Thermal conductivities of most of the liquids __________ with rise in temperature.
Thermal conductivities of most of the liquids __________ with rise in temperature.
The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of 'n' is exactly 4 for
The thermal radiation emitted by a body is proportional to Tn, where T is its absolute temperature. The value of 'n' is exactly 4 for
In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to __________ the velocity head.
In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to __________ the velocity head.
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
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
For heat flow through very thick walled cylinder, use____mean radius.
For heat flow through very thick walled cylinder, use____mean radius.
For a laminar flow of fluid in a circular tube, 'h₁' is the convective heat transfer co-efficient at velocity 'V₁'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is
For a laminar flow of fluid in a circular tube, 'h₁' is the convective heat transfer co-efficient at velocity 'V₁'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is
Thermal conductivity of a gas at low density, __________ with increase in temperature.
Thermal conductivity of a gas at low density, __________ with increase in temperature.
Baffles in the shell side of a shell and tube heat exchanger
Baffles in the shell side of a shell and tube heat exchanger
If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length
If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length
The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ΔT = Temperature drop across condensate film )
The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ΔT = Temperature drop across condensate film )
When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is
When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is
In evaporators, lowering the feed temperature
In evaporators, lowering the feed temperature
In a forward feed multiple effect, the pressure build up will be
In a forward feed multiple effect, the pressure build up will be
Stefan-Boltzman law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K )
Stefan-Boltzman law which describes the radiation heat transfer states that, it is proportional to (where, t = temperature in °C T = absolute temperature in ° K )
Tube expansion allowances exist in __________ heat exchanger.
Tube expansion allowances exist in __________ heat exchanger.
The equation, Nst = f/2, is the __________ analogy.
The equation, Nst = f/2, is the __________ analogy.
h.D/K is called the __________ number.
h.D/K is called the __________ number.
The maximum heat transfer co-efficient from steam heating will be attained when the steam is
The maximum heat transfer co-efficient from steam heating will be attained when the steam is
With increase in temperature, the thermal conductivity of non-metallic amorphous solids
With increase in temperature, the thermal conductivity of non-metallic amorphous solids
Double pipe heat exchangers are used
Double pipe heat exchangers are used
A hot liquid is kept in a big room. The logorithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an
A hot liquid is kept in a big room. The logorithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an
Evaporation of 1kg of water from a solution in a single effect evaporator requires about __________ kg of steam.
Evaporation of 1kg of water from a solution in a single effect evaporator requires about __________ kg of steam.
Steam is to be condensed in a shell and tube heat exchanger, 5 m long with a shell diameter of 1 m. Cooling water is to be used for removing the heat. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same. The best arrangement is
Steam is to be condensed in a shell and tube heat exchanger, 5 m long with a shell diameter of 1 m. Cooling water is to be used for removing the heat. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same. The best arrangement is
For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in
For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in
When vaporisation takes place directly at the heating surface, it is called
When vaporisation takes place directly at the heating surface, it is called
In a co-current double pipe heat exchanger used for condensing saturated steam over the inner tube, if the entrance and exit conditions of the coolant are interchanged, then the rate of condensation will
In a co-current double pipe heat exchanger used for condensing saturated steam over the inner tube, if the entrance and exit conditions of the coolant are interchanged, then the rate of condensation will
With increase in temperature, the thermal conductivity of a gas
With increase in temperature, the thermal conductivity of a gas
If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will
If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased.
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased.
Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around __________ BTU.
Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around __________ BTU.
The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as
The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as
A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of
A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of
In a heat exchanger, floating head is provided to
In a heat exchanger, floating head is provided to
A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to
A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to
Temperature profile in steady state heat transfer is
Temperature profile in steady state heat transfer is
Viscosity of gases __________ with increase in temperature.
Viscosity of gases __________ with increase in temperature.
In forced convection, the heat transfer depends on
In forced convection, the heat transfer depends on
Which is the most suitable for the con-certration of highly concentrated solution?
Which is the most suitable for the con-certration of highly concentrated solution?
Which of the following is concerned with both heat and mass transfer?
Which of the following is concerned with both heat and mass transfer?
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by
Convective heat transfer, in which heat is transferred by movement of warmed matter is described by
Convective heat transfer, in which heat is transferred by movement of warmed matter is described by
The unit of heat transfer co-efficient is
The unit of heat transfer co-efficient is
Pick out the wrong statement.
Pick out the wrong statement.
At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the
At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the
If h₁ = inner film co-efficient and /h₂ = outer film co-efficient, then the overall heat transfer co-efficient is
If h₁ = inner film co-efficient and /h₂ = outer film co-efficient, then the overall heat transfer co-efficient is
Thermal diffusivity is the most important in heat transfer by
Thermal diffusivity is the most important in heat transfer by
Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer.
Controlling heat transfer film co-efficient is the one, which offers __________ resistance to heat transfer.
Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water.
Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water.
Pick out the wrong statement.
Pick out the wrong statement.
View factor is important in heat transfer by
View factor is important in heat transfer by
Heat transfer by radiation between two bodies at T₁ & T₂ and in an ambient temperature of Ta°C depends on
Heat transfer by radiation between two bodies at T₁ & T₂ and in an ambient temperature of Ta°C depends on
For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is
For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is
Fqra cold viscous feed, backward feed gives __________ than forward feed.
Fqra cold viscous feed, backward feed gives __________ than forward feed.
In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid
In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid
The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m². The approximate surface temperature (K) is
(Stefan-Boltzman constant = 5.67xl0⁻⁸ W/m².K⁴)
The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m². The approximate surface temperature (K) is
(Stefan-Boltzman constant = 5.67xl0⁻⁸ W/m².K⁴)
Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re0.8 . Prn, is not valid, if the value of
Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re0.8 . Prn, is not valid, if the value of
The film co-efficient between condensing vapour and metal wall increases with
The film co-efficient between condensing vapour and metal wall increases with
Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU.
Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU.
Increasing the liquor level in the evaporator results in the
Increasing the liquor level in the evaporator results in the
It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is
It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is
It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is
It is desired to concentrate a 20% salt solution (20 kg of salt in 100 kg of solution) to a 30% salt solution in an evaporator. Consider a feed of 300 kg/min at 30°C. The boiling point of the solution is 110°C, the latent heat of vaporisation is 2100 kJ/kg and the specific heat of the solution is 4 kJ/kg.K. The rate at which the heat has to be supplied in (kJ/min) to the evaporator is
When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling.
When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling.
200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 x 10⁻³ kg/m².s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m²/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)
200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 x 10⁻³ kg/m².s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m²/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)
The rate of emission of radiation by a body does not depend upon the
The rate of emission of radiation by a body does not depend upon the
The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C-1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m⁻².°C-1. The rate of heat loss from the outer surface in W.m-2is
The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C-1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m⁻².°C-1. The rate of heat loss from the outer surface in W.m-2is
Economy of a multiple effect evaporator is not influenced much by the
Economy of a multiple effect evaporator is not influenced much by the
