*/*_Boiling point elevation of an ideal solution?

Decreases rapidly with temperature rise

Increases rapidly with temperature rise

Decreases rapidly with temperature rise

%_Log mean temperature difference (LMTD) cannot be used, if_%

Heat transfer co-efficient over the entire heat exchanger is not constant

The heat capacity is not constant and there is a phase change

Does not provide a safety factor for design

Accounts for additional resistances to heat flow

%_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_%

Constant temperature equal to that of the base

%_What is the unit of thermal conductivity ?_%

Kcal/hr. m¬¨‚â§ ¬¨‚àûC

%_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_%

From one part of a body to the another part of the same body

Between two bodies in physical contact with each other

Between two bodies not in physical contact with each other

From one part of a body to the another part of the same body

%_The purpose of floating head in a heat exchanger is to_%

Facilitate its lengthening, if needed

482 + Mcqs in Heat Transfer in Chemical Engineering Page 4 McqOptions

151.	/_What is the thermal conductivity of a perfect heat insulator??
A.	Zero
B.	One
C.	‚Äö√ √ª
D.	Between 0 and ‚Äö√ √ª
Answer» B. One

Discussion

152.	/_In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to __________ the velocity head.?
A.	Twice
B.	Four times
C.	Square root of
D.	Square of
Answer» C. Square root of

Discussion

153.	/_'Duhring's plot' is of use in?
A.	Extractive distillation
B.	Evaporation
C.	Leaching
D.	Absorption
Answer» C. Leaching

Discussion

154.	/_A black body does not __________ radiation.?
A.	Absorb or emit
B.	Refract
C.	Reflect
D.	Both B & C
Answer» E.

Discussion

155.	/_In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.?
A.	Geometric
B.	Arithmetic
C.	Logarithmic
D.	Either A, B or C
Answer» D. Either A, B or C

Discussion

156.	/_Natural convection is characterised by?
A.	Grashhoff number
B.	Peclet number
C.	Reynolds number
D.	Prandtl number
Answer» B. Peclet number

Discussion

157.	/_Choose the correct equation.?
A.	Nu = (Re) (Pr) (Gz)
B.	Nu = (Re) (Pr) (St)
C.	Nu = (Re)(Pr)
D.	Nu = (Pr)(St)
Answer» C. Nu = (Re)(Pr)

Discussion

158.	/_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
Answer» D. Conduction

Discussion

159.	/_Heat transfer co-efficient (h1) for liquids increases with?
A.	Increasing temperature
B.	Decreasing temperature
C.	Decreasing Reynolds number
D.	None of these
Answer» B. Decreasing temperature

Discussion

160.	/_Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.?
A.	Stefan's
B.	Dalton's
C.	Wien's
D.	Kirchoffs
Answer» D. Kirchoffs

Discussion

161.	/_For what value of Prandtl number, St = f/2??
A.	1.5
B.	1
C.	> 1
D.	< 1
Answer» C. > 1

Discussion

162.	/_Baffles are provided in heat exchangers to increase the?
A.	Fouling factor
B.	Heat transfer area
C.	Heat transfer co-efficient
D.	Heat transfer rate
Answer» D. Heat transfer rate

Discussion

163.	/_Film condensation is promoted on a/an __________ surface.?
A.	Oily
B.	Coated
C.	Clean & smooth
D.	Dirty
Answer» D. Dirty

Discussion

164.	/_Boiling point elevation of an ideal solution?
A.	Increases rapidly with temperature rise
B.	Decreases rapidly with temperature rise
C.	In independent of pressure
D.	Both B and C
Answer» B. Decreases rapidly with temperature rise

Discussion

165.	/_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.	D0.8
B.	D-0.2
C.	D-1
D.	D-1.8
Answer» C. D-1

Discussion

166.	/_Tube pitch is the __________ of tube diameters and the clearances.?
A.	Sum
B.	Difference
C.	Ratio
D.	None of these
Answer» B. Difference

Discussion

167.	/_For a laminar flow of fluid in a circular tube, 'h‚Äö√á√Ö' is the convective heat transfer co-efficient at velocity 'V‚Äö√á√Ö'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is?
A.	1.26 h‚Äö√á√Ö
B.	0.794 h‚Äö√á√Ö
C.	0.574 h‚Äö√á√Ö
D.	1.741 h‚Äö√á√Ö
Answer» C. 0.574 h‚Äö√á√Ö

Discussion

168.	/_When vaporisation takes place directly at the heating surface, it is called?
A.	Film boiling
B.	Nucleate boiling
C.	Vapour binding
D.	None of these
Answer» C. Vapour binding

Discussion

169.	/_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.	2
B.	20.8
C.	20.2
D.	20.5
Answer» C. 20.2

Discussion

170.	/_In a multiple effect evaporator, the effect of boiling point elevation is to?
A.	Reduce the capacity
B.	Reduce the economy
C.	Increase the economy
D.	None of these
Answer» B. Reduce the economy

Discussion

171.	/_In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)?
A.	D/5 and D
B.	D/2 and 2 D
C.	D/4 and 2 D
D.	D and 2 D
Answer» B. D/2 and 2 D

Discussion

172.	/_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.?
A.	Parallel
B.	Mixed
C.	Counterflow
D.	Same in either A, B or C
Answer» E.

Discussion

173.	%_Log mean temperature difference (LMTD) cannot be used, if_%
A.	Heat transfer co-efficient over the entire heat exchanger is not constant
B.	There exists an unsteady state
C.	The heat capacity is not constant and there is a phase change
D.	None of these
Answer» E.

Discussion

174.	%_Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100¬¨‚àûC and the inside heat transfer co-efficient is 3k/l. If the wall temperature on the outside is held at 25¬¨‚àûC, what is the inside wall temperature in degree centigrade?_%
A.	35.5
B.	43.75
C.	81.25
D.	48.25
Answer» D. 48.25

Discussion

175.	%_Evaporator tubes are generally_%
A.	Horizontal
B.	Vertical
C.	Inclined
D.	Random
Answer» C. Inclined

Discussion

176.	%_Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low_%
A.	Hardness
B.	Dissolved soilds content
C.	Suspended solids content
D.	All of the above
Answer» E.

Discussion

177.	%_The rate of heat transfer is a product of overall heat transfer co-efficient, the difference in temperature and the_%
A.	Heating volume
B.	Heat transfer area
C.	Nusselt number
D.	None of these
Answer» C. Nusselt number

Discussion

178.	%_The sum of reflectivity and absorptivity for an opaque body is equal to_%
A.	0.5
B.	1
C.	0
D.	2
Answer» C. 0

Discussion

179.	%_Fouling factor_%
A.	Is a dimensionless quantity
B.	Does not provide a safety factor for design
C.	Accounts for additional resistances to heat flow
D.	None of these
Answer» D. None of these

Discussion

180.	%_Heat transfer in the laminar sublayer in case of a liquid flowing through a pipe, is mostly by_%
A.	Eddies current
B.	Conduction
C.	Convection
D.	None of these
Answer» C. Convection

Discussion

181.	%_Heat transfer co-efficient (h1) for liquids increases with_%
A.	Increasing temperature
B.	Decreasing temperature
C.	Decreasing Reynolds number
D.	None of these
Answer» B. Decreasing temperature

Discussion

182.	%_Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law._%
A.	Stefan's
B.	Dalton's
C.	Wien's
D.	Kirchoffs
Answer» D. Kirchoffs

Discussion

183.	%_Choose the correct equation._%
A.	Nu = (Re) (Pr) (Gz)
B.	Nu = (Re) (Pr) (St)
C.	Nu = (Re)(Pr)
D.	Nu = (Pr)(St)
Answer» C. Nu = (Re)(Pr)

Discussion

184.	%_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
Answer» D. Conduction

Discussion

185.	%_In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate._%
A.	Geometric
B.	Arithmetic
C.	Logarithmic
D.	Either A, B or C
Answer» D. Either A, B or C

Discussion

186.	%_Natural convection is characterised by_%
A.	Grashhoff number
B.	Peclet number
C.	Reynolds number
D.	Prandtl number
Answer» B. Peclet number

Discussion

187.	%_'Duhring's plot' is of use in_%
A.	Extractive distillation
B.	Evaporation
C.	Leaching
D.	Absorption
Answer» C. Leaching

Discussion

188.	%_A black body does not __________ radiation._%
A.	Absorb or emit
B.	Refract
C.	Reflect
D.	Both B & C
Answer» E.

Discussion

189.	%_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_%
A.	Surrounding temperature
B.	Average temperature of the fin
C.	Temperature of the fin end
D.	Constant temperature equal to that of the base
Answer» E.

Discussion

190.	%_What is the unit of thermal conductivity ?_%
A.	Kcal/hr. m¬¨‚â§ ¬¨‚àûC
B.	Kcal/hr.m.¬¨‚àûC
C.	Kcal/hr.m
D.	Kcal/hr. ¬¨‚àûC
Answer» C. Kcal/hr.m

Discussion

191.	%_The heat flux in the nucleate boiling regimes is proportional to (where, ≈í√ÆT = excess temperature)_%
A.	(≈í√ÆT)¬¨‚â§
B.	(≈í√ÆT)‚Äö√Ö¬•
C.	(≈í√ÆT)¬¨‚â•
D.	‚Äö√ √∂(≈í√ÆT)
Answer» D. ‚Äö√ √∂(≈í√ÆT)

Discussion

192.	%_Which of the following accessories is provided in the vapor line of an evaporator for removing the entrained liquid?_%
A.	Bleed point
B.	Vent
C.	Catchall
D.	Baffle
Answer» D. Baffle

Discussion

193.	%_In a shell and tube heat exchanger, the shell side fluid velocity can not be changed by changing the_%
A.	Tube layout
B.	Tube diameter
C.	Tube pitch
D.	No. of baffles
Answer» C. Tube pitch

Discussion

194.	%_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_%
A.	> 0.75
B.	< 0.75
C.	< 0.50
D.	< 0.25
Answer» C. < 0.50

Discussion

195.	%_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_%
A.	Between two bodies in physical contact with each other
B.	Between two bodies not in physical contact with each other
C.	From one part of a body to the another part of the same body
D.	Both B & C
Answer» C. From one part of a body to the another part of the same body

Discussion

196.	%_What is the steam economy in case of a single effect evaporator system?_%
A.	1
B.	>1
C.	< 1
D.	0.1
Answer» D. 0.1

Discussion

197.	%_An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is_%
A.	4000
B.	9000
C.	4600
D.	3000
Answer» B. 9000

Discussion

198.	%_The purpose of floating head in a heat exchanger is to_%
A.	Avoid buckling of tubes
B.	Provide support for tubes
C.	Decrease the pressure drop
D.	Facilitate its lengthening, if needed
Answer» B. Provide support for tubes

Discussion

199.	%_The driving potential for the crystal growth during crystallisation is the __________ of the solution._%
A.	Concentration
B.	Viscosity
C.	Super-saturation
D.	Density
Answer» D. Density

Discussion

200.	%_The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K= 0.04 W/m.¬¨‚àûK and thickness 0.16m is 10 W/m¬¨‚â§. The temperature of the inside wall is - 5¬¨‚àûC. The outside wall temperature is_%
A.	25¬¨‚àûC
B.	30¬¨‚àûC
C.	35¬¨‚àûC
D.	40¬¨‚àûC
Answer» D. 40¬¨‚àûC

Discussion

Explore topic-wise MCQs in Chemical Engineering.

*/*_What is the thermal conductivity of a perfect heat insulator??

*/*_In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to __________ the velocity head.?

*/*_'Duhring's plot' is of use in?

*/*_A black body does not __________ radiation.?

*/*_In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.?

*/*_Natural convection is characterised by?

*/*_Choose the correct equation.?

*/*_Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called?

*/*_Heat transfer co-efficient (h1) for liquids increases with?

*/*_Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.?

*/*_For what value of Prandtl number, St = f/2??

*/*_Baffles are provided in heat exchangers to increase the?

*/*_Film condensation is promoted on a/an __________ surface.?

*/*_Boiling point elevation of an ideal solution?

*/*_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?

*/*_Tube pitch is the __________ of tube diameters and the clearances.?

*/*_For a laminar flow of fluid in a circular tube, 'h‚Äö√á√Ö' is the convective heat transfer co-efficient at velocity 'V‚Äö√á√Ö'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is?

*/*_When vaporisation takes place directly at the heating surface, it is called?

*/*_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 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)?

*/*_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.?

%_Log mean temperature difference (LMTD) cannot be used, if_%

%_Evaporator tubes are generally_%

%_Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low_%

%_The rate of heat transfer is a product of overall heat transfer co-efficient, the difference in temperature and the_%

%_The sum of reflectivity and absorptivity for an opaque body is equal to_%

%_Fouling factor_%

%_Heat transfer in the laminar sublayer in case of a liquid flowing through a pipe, is mostly by_%

%_Heat transfer co-efficient (h1) for liquids increases with_%

%_Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law._%

%_Choose the correct equation._%

%_Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called_%

%_In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate._%

%_Natural convection is characterised by_%

%_'Duhring's plot' is of use in_%

%_A black body does not __________ radiation._%

%_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_%

%_What is the unit of thermal conductivity ?_%

%_The heat flux in the nucleate boiling regimes is proportional to (where, ≈í√ÆT = excess temperature)_%

%_Which of the following accessories is provided in the vapor line of an evaporator for removing the entrained liquid?_%

%_In a shell and tube heat exchanger, the shell side fluid velocity can not be changed by changing 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_%

%_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 steam economy in case of a single effect evaporator system?_%

%_An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is_%

%_The purpose of floating head in a heat exchanger is to_%

%_The driving potential for the crystal growth during crystallisation is the __________ of the solution._%

%_The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K= 0.04 W/m.¬¨‚àûK and thickness 0.16m is 10 W/m¬¨‚â§. The temperature of the inside wall is - 5¬¨‚àûC. The outside wall temperature is_%

/_What is the thermal conductivity of a perfect heat insulator??

/_In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to __________ the velocity head.?

/_'Duhring's plot' is of use in?

/_A black body does not __________ radiation.?

/_In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.?

/_Natural convection is characterised by?

/_Choose the correct equation.?

/_Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called?

/_Heat transfer co-efficient (h1) for liquids increases with?

/_Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.?

/_For what value of Prandtl number, St = f/2??

/_Baffles are provided in heat exchangers to increase the?

/_Film condensation is promoted on a/an __________ surface.?

/_Boiling point elevation of an ideal solution?

/_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?

/_Tube pitch is the __________ of tube diameters and the clearances.?

/_For a laminar flow of fluid in a circular tube, 'h‚Äö√á√Ö' is the convective heat transfer co-efficient at velocity 'V‚Äö√á√Ö'. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is?

/_When vaporisation takes place directly at the heating surface, it is called?

/_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 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)?

/_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.?