*/*_The film co-efficient between condensing vapour and metal wall increases with?

Decreasing temperature of the vapour

Increasing temperature of the vapour

Decreasing temperature of the vapour

Increasing viscosity of the film of condensate

*/*_In evaporators, lowering the feed temperature?

Decreases the heating area required

Increases the heating area required

Decreases the heating area required

*/*_If h‚Äö√á√Ö = inner film co-efficient and /h‚Äö√á√á = outer film co-efficient, then the overall heat transfer co-efficient is?

Always higher than h‚Äö√á√á

Always less than h‚Äö√á√Ö

Always between h‚Äö√á√Ö and h‚Äö√á√á

Always higher than h‚Äö√á√á

*/*_The advantage of backward feed multiple effect evaporators over forward feed units is that?

Equal heat transfer co-efficients exist in various effects

Heat sensitive material can be handled

There is no additional cost of pumping

Most concentrated liquid is at highest temperature

Equal heat transfer co-efficients exist in various effects

*/*_The units of resistance to heat transfer is?

J.m‚Äö√Ö¬™¬¨‚â§.K‚Äö√Ö¬™¬¨œÄ

J.m‚Äö√Ö¬™¬¨œÄ.K‚Äö√Ö¬™¬¨œÄ

W.m‚Äö√Ö¬™¬¨‚â§.K‚Äö√Ö¬™¬¨œÄ

W‚Äö√Ö¬™¬¨œÄm¬¨‚â§K

*/*_A body cools down from 75¬¨‚àûC to 70¬¨‚àûC in 10 minutes. It will cool down from 70¬¨‚àû C to 65¬¨‚àû C in __________ minutes.?

Either B or C, depends on the mass of the body

*/*_Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping?

The top tube sheet floating and bottom tube sheet fixed

The top tube sheet fixed and the bottom tube-sheet floating

*/*_Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is?

Thin walled having the value of Ao Ai/< 2

*/*_Thermal conductivities of most of the liquids __________ with rise in temperature.?

May increase or decrease; depends on the liquid

*/*_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?

Giving the surface a mirror finish

Painting the surface white (with aluminium paint)

Giving the surface a mirror finish

*/*_A 2-4 heat exchanger involves?

Smaller pressure drop compared to 1-2 exchanger

Both counter and parallel-flow of the fluids

Smaller pressure drop compared to 1-2 exchanger

*/*_Terminal point temperature differences between fluids in case of a heat exchanger is termed as?

Log mean temperature difference

Arithmetic mean temperature difference

Geometric mean temperature difference

*/*_With increase in temperature, the thermal conductivity of fresh lubricating oil?

May increase or decrease; depends on its composition

*/*_The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness)?

‚Äö√ √π ‚Äö√ √∂t

*/*_In sub-cooled boiling,?

Bubbles from heating surface are absorbed by the mass of the liquid

Temperature of the heating surface is less than the boiling point of the liquid

Temperature of the heating surface is more than the boiling point of the liquid

Bubbles from heating surface are absorbed by the mass of the liquid

Very large vapour space is necessary

*/*_Overall heat transfer co-efficient of a particular tube is U‚Äö√á√Ö. If the same tube with some dirt deposited on either side has coefficient U‚Äö√á√á, then?

U‚Äö√á√á > U‚Äö√á√Ö

U‚Äö√á√Ö = U‚Äö√á√á

U‚Äö√á√á > U‚Äö√á√Ö

U‚Äö√á√Ö > U‚Äö√á√á

U‚Äö√á√Ö = dirt factor - U‚Äö√á√á

482 + Mcqs in Heat Transfer in Chemical Engineering Page 3 McqOptions

101.	*$_The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is?
A.	2
B.	1/2
C.	4
D.	1/4
Answer» E.

Discussion

102.	/_The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ≈í√ÆT = Temperature drop across condensate film )?
A.	(≈í√ÆT)2
B.	‚Äö√ √∂≈í√ÆT
C.	(≈í√ÆT)1/4
D.	(≈í√ÆT)3/2
Answer» D. (≈í√ÆT)3/2

Discussion

103.	/_The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m¬¨‚â§. The approximate surface temperature (K) is (Stefan-Boltzman constant = 5.67xl0‚Äö√Ö¬™‚Äö√Ö‚àè W/m¬¨‚â§.K‚Äö√Ö¬•)?
A.	1000
B.	727
C.	800
D.	1200
Answer» B. 727

Discussion

104.	/_Which of the following is concerned with both heat and mass transfer??
A.	Lewis relationship
B.	Nusselt number
C.	Kutateladze number
D.	Froude number
Answer» B. Nusselt number

Discussion

105.	/_The film co-efficient between condensing vapour and metal wall increases with?
A.	Increasing temperature of the vapour
B.	Decreasing temperature of the vapour
C.	Increasing viscosity of the film of condensate
D.	Increasing temperature drop
Answer» B. Decreasing temperature of the vapour

Discussion

106.	/_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
Answer» C. Forced convection

Discussion

107.	/_In evaporators, lowering the feed temperature?
A.	Increases the heating area required
B.	Reduces the economy
C.	Both A and B
D.	Decreases the heating area required
Answer» D. Decreases the heating area required

Discussion

108.	/_Which is the most suitable for the con-certration of highly concentrated solution??
A.	Open pan evaporation
B.	Long tube vertical evaporator
C.	Agitated film evaporator
D.	None of these
Answer» B. Long tube vertical evaporator

Discussion

109.	/_If h‚Äö√á√Ö = inner film co-efficient and /h‚Äö√á√á = outer film co-efficient, then the overall heat transfer co-efficient is?
A.	Always less than h‚Äö√á√Ö
B.	Always between h‚Äö√á√Ö and h‚Äö√á√á
C.	Always higher than h‚Äö√á√á
D.	Dependent on metal resistance
Answer» C. Always higher than h‚Äö√á√á

Discussion

110.	/_In forced convection, the Nusselt number is a function of?
A.	Re and Pr
B.	Re and Gr
C.	Pr and Gr
D.	Re and Sc
Answer» B. Re and Gr

Discussion

111.	/_While the total emissivity of a perfect black body is unity, the same for a real body is?
A.	0
B.	1
C.	> 1
D.	Between 0 and 1
Answer» E.

Discussion

112.	/_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
Answer» E.

Discussion

113.	/_The advantage of backward feed multiple effect evaporators over forward feed units is that?
A.	Heat sensitive material can be handled
B.	There is no additional cost of pumping
C.	Most concentrated liquid is at highest temperature
D.	Equal heat transfer co-efficients exist in various effects
Answer» D. Equal heat transfer co-efficients exist in various effects

Discussion

114.	/_A hot body will radiate heat most rapidly, if its surface is?
A.	White & rough
B.	Black & rough
C.	White & polished
D.	Black & polished
Answer» C. White & polished

Discussion

115.	/_The purpose of providing a 'catchall' in the vapor line of an evaporator is to?
A.	Create vacuum
B.	Regulate the vapor flow
C.	Vent the non-condensible gases
D.	Arrest the entrained liquid
Answer» E.

Discussion

116.	/_Fourier's law applies to the heat transfer by?
A.	Convection
B.	Radiation
C.	Conduction
D.	All of the above
Answer» D. All of the above

Discussion

117.	/_Kirchoff s law applies to __________ radiation.?
A.	Total
B.	Monochromatic
C.	Both A & B
D.	Neither A nor B
Answer» D. Neither A nor B

Discussion

118.	/___________ equation relates the thermal conductivity of a solid to its temperature.?
A.	Antonie
B.	Kopp's
C.	Lee's
D.	Kistyakowski
Answer» D. Kistyakowski

Discussion

119.	/_The units of resistance to heat transfer is?
A.	J.m‚Äö√Ö¬™¬¨‚â§.K‚Äö√Ö¬™¬¨œÄ
B.	J.m‚Äö√Ö¬™¬¨œÄ.K‚Äö√Ö¬™¬¨œÄ
C.	W.m‚Äö√Ö¬™¬¨‚â§.K‚Äö√Ö¬™¬¨œÄ
D.	W‚Äö√Ö¬™¬¨œÄm¬¨‚â§K
Answer» E.

Discussion

120.	/_Nusselt number is the ratio of the temperature gradient at the wall to?
A.	Temperature difference
B.	Heat flux
C.	That across the entire pipe
D.	None of these
Answer» D. None of these

Discussion

121.	/_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.	Concentrations
B.	Chemical potentials
C.	Activity co-efficients
D.	Mass transfer co-efficients
Answer» B. Chemical potentials

Discussion

122.	/_Forced circulation evaporators are normally used for concentrating liquids having?
A.	Scaling characteristics
B.	High viscosity
C.	Both A & B
D.	Neither A nor B
Answer» D. Neither A nor B

Discussion

123.	/_A body cools down from 75¬¨‚àûC to 70¬¨‚àûC in 10 minutes. It will cool down from 70¬¨‚àû C to 65¬¨‚àû C in __________ minutes.?
A.	10
B.	>10
C.	<10
D.	Either B or C, depends on the mass of the body
Answer» C. <10

Discussion

124.	/_Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping?
A.	Both the tube sheets fixed
B.	Both the tube sheets floating
C.	The top tube sheet floating and bottom tube sheet fixed
D.	The top tube sheet fixed and the bottom tube-sheet floating
Answer» B. Both the tube sheets floating

Discussion

125.	/_Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is?
A.	Thin walled having the value of Ao Ai/< 2
B.	Thick walled
C.	Having the value of Ao/Ai > 2
D.	Both B and C
Answer» B. Thick walled

Discussion

126.	/_Crystallisation of solids from a homogeneous solution is a/an __________ process.?
A.	Exothermic
B.	Mildly endothermic
C.	Highly endothermic
D.	None of these
Answer» B. Mildly endothermic

Discussion

127.	/_Which of the following has the minimum thermal conductivity??
A.	Nitrogen
B.	Steel
C.	Carbon black
D.	Tar
Answer» B. Steel

Discussion

128.	/_In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is?
A.	Minimum
B.	Maximum
C.	Zero
D.	Infinity
Answer» D. Infinity

Discussion

129.	/_Mechanical recompression evaporation is used in the production of?
A.	Alcohol
B.	Distilled water
C.	Salt
D.	Fruits jam
Answer» C. Salt

Discussion

130.	/_Grashoff number, which is defined as g . ≈í‚â§(Ts - T‚Äö√ √ª) ≈ì√Ö¬¨‚â§. L¬¨‚â•/≈í¬∫¬¨‚â§, is proportional to the ratio of buoyancy force to __________ force.?
A.	Viscous
B.	Elastic
C.	Inertial
D.	None of these
Answer» B. Elastic

Discussion

131.	/_The Stefan-Boltzman constant depends on the?
A.	Medium
B.	Temperature
C.	Surface
D.	None of these
Answer» E.

Discussion

132.	/_According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor)?
A.	2f
B.	f
C.	f/2
D.	f/4
Answer» D. f/4

Discussion

133.	/_Convective heat transfer, in which heat is transferred by movement of warmed matter is described by?
A.	Fourier's law
B.	Newton's law of cooling
C.	Fick's law
D.	None of these
Answer» C. Fick's law

Discussion

134.	/_For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in?
A.	Increased economy
B.	Decreased economy
C.	Lower capacity
D.	No effect on economy
Answer» B. Decreased economy

Discussion

135.	/_Heat flux, as defined in heat flow is analogous to __________ in electricity flow.?
A.	Current
B.	Voltage
C.	Resistance
D.	None of these
Answer» B. Voltage

Discussion

136.	/_A graph between __________ is called Wilson plot.?
A.	1/U Vs . 1/v0.8
B.	1/v0.8 Vs . U
C.	V0.8 Vs . U
D.	1/U Vs . 1/V
Answer» B. 1/v0.8 Vs . U

Discussion

137.	/_Thermal conductivities of most of the liquids __________ with rise in temperature.?
A.	Increases
B.	Decreases
C.	Remains unchanged
D.	May increase or decrease; depends on the liquid
Answer» C. Remains unchanged

Discussion

138.	/_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?
A.	Painting the surface black
B.	Painting the surface white (with aluminium paint)
C.	Giving the surface a mirror finish
D.	Roughening the surface
Answer» C. Giving the surface a mirror finish

Discussion

139.	/_A 2-4 heat exchanger involves?
A.	Only counter-flow of fluids
B.	Only parallel-flow of fluids
C.	Both counter and parallel-flow of the fluids
D.	Smaller pressure drop compared to 1-2 exchanger
Answer» D. Smaller pressure drop compared to 1-2 exchanger

Discussion

140.	/_Terminal point temperature differences between fluids in case of a heat exchanger is termed as?
A.	Approach
B.	Log mean temperature difference
C.	Arithmetic mean temperature difference
D.	Geometric mean temperature difference
Answer» B. Log mean temperature difference

Discussion

141.	/_Which of the following has the lowest overall heat transfer co-efficient??
A.	Dowtherm
B.	Molten sodium
C.	Water
D.	Air
Answer» E.

Discussion

142.	/_With increase in temperature, the thermal conductivity of fresh lubricating oil?
A.	Increases
B.	Decreases
C.	Remains unchanged
D.	May increase or decrease; depends on its composition
Answer» C. Remains unchanged

Discussion

143.	/_The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness)?
A.	‚Äö√ √π t
B.	‚Äö√ √π 1/t
C.	‚Äö√ √π ‚Äö√ √∂t
D.	Independent of 't'
Answer» C. ‚Äö√ √π ‚Äö√ √∂t

Discussion

144.	/_A black body when hot, emits heat radiation of __________ wavelengths.?
A.	Small
B.	Large
C.	All
D.	One fixed
Answer» D. One fixed

Discussion

145.	/_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
Answer» C. Bubbles from heating surface are absorbed by the mass of the liquid

Discussion

146.	/_The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe )?
A.	K/h0
B.	2K/h0
C.	hi/K
D.	2hi/K
Answer» B. 2K/h0

Discussion

147.	/_Three material A, B and C of equal thick-nes and of thermal conductivity of 20, 40 & 60 kcal/hr. m. ¬¨‚àûC respectively are joined together. The temperature outside of A and C are 30¬¨‚àûC and 100¬¨‚àûC respectively. The interface between B and C will be at a temperature of __________ ¬¨‚àûC.?
A.	40
B.	95
C.	70
D.	50
Answer» D. 50

Discussion

148.	/_Resistance to heat flow by conduction is proportional to (where, t & ≈ì√Ö are thickness & density of the material respectively and A = area normal to the direction of heat flow. )?
A.	T
B.	1/≈ì√Ö
C.	1/A
D.	All of the above
Answer» E.

Discussion

149.	/_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.	Ellipse
B.	Straight line
C.	Parabola
D.	Circular arc
Answer» C. Parabola

Discussion

150.	/_Overall heat transfer co-efficient of a particular tube is U‚Äö√á√Ö. If the same tube with some dirt deposited on either side has coefficient U‚Äö√á√á, then?
A.	U‚Äö√á√Ö = U‚Äö√á√á
B.	U‚Äö√á√á > U‚Äö√á√Ö
C.	U‚Äö√á√Ö > U‚Äö√á√á
D.	U‚Äö√á√Ö = dirt factor - U‚Äö√á√á
Answer» B. U‚Äö√á√á > U‚Äö√á√Ö

Discussion

Explore topic-wise MCQs in Chemical Engineering.

*$_The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is?

*/*_The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ≈í√ÆT = Temperature drop across condensate film )?

*/*_The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m¬¨‚â§. The approximate surface temperature (K) is (Stefan-Boltzman constant = 5.67xl0‚Äö√Ö¬™‚Äö√Ö‚àè W/m¬¨‚â§.K‚Äö√Ö¬•)?

*/*_Which of the following is concerned with both heat and mass transfer??

*/*_The film co-efficient between condensing vapour and metal wall increases with?

*/*_Mode of heat transfer involved in the cooling of air cooled internal combustion engine is?

*/*_In evaporators, lowering the feed temperature?

*/*_Which is the most suitable for the con-certration of highly concentrated solution??

*/*_If h‚Äö√á√Ö = inner film co-efficient and /h‚Äö√á√á = outer film co-efficient, then the overall heat transfer co-efficient is?

*/*_In forced convection, the Nusselt number is a function of?

*/*_While the total emissivity of a perfect black body is unity, the same for a real body is?

*/*_If heat transfer rate varies with the time, it is termed as?

*/*_The advantage of backward feed multiple effect evaporators over forward feed units is that?

*/*_A hot body will radiate heat most rapidly, if its surface is?

*/*_The purpose of providing a 'catchall' in the vapor line of an evaporator is to?

*/*_Fourier's law applies to the heat transfer by?

*/*_Kirchoff s law applies to __________ radiation.?

*/*___________ equation relates the thermal conductivity of a solid to its temperature.?

*/*_The units of resistance to heat transfer is?

*/*_Nusselt number is the ratio of the temperature gradient at the wall to?

*/*_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?

*/*_Forced circulation evaporators are normally used for concentrating liquids having?

*/*_A body cools down from 75¬¨‚àûC to 70¬¨‚àûC in 10 minutes. It will cool down from 70¬¨‚àû C to 65¬¨‚àû C in __________ minutes.?

*/*_Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping?

*/*_Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is?

*/*_Crystallisation of solids from a homogeneous solution is a/an __________ process.?

*/*_Which of the following has the minimum thermal conductivity??

*/*_In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is?

*/*_Mechanical recompression evaporation is used in the production of?

*/*_Grashoff number, which is defined as g . ≈í‚â§(Ts - T‚Äö√ √ª) ≈ì√Ö¬¨‚â§. L¬¨‚â•/≈í¬∫¬¨‚â§, is proportional to the ratio of buoyancy force to __________ force.?

*/*_The Stefan-Boltzman constant depends on the?

*/*_According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor)?

*/*_Convective heat transfer, in which heat is transferred by movement of warmed matter is described by?

*/*_For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in?

*/*_Heat flux, as defined in heat flow is analogous to __________ in electricity flow.?

*/*_A graph between __________ is called Wilson plot.?

*/*_Thermal conductivities of most of the liquids __________ with rise in temperature.?

*/*_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?

*/*_A 2-4 heat exchanger involves?

*/*_Terminal point temperature differences between fluids in case of a heat exchanger is termed as?

*/*_Which of the following has the lowest overall heat transfer co-efficient??

*/*_With increase in temperature, the thermal conductivity of fresh lubricating oil?

*/*_The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness)?

*/*_A black body when hot, emits heat radiation of __________ wavelengths.?

*/*_In sub-cooled boiling,?

*/*_The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe )?

*/*_Resistance to heat flow by conduction is proportional to (where, t & ≈ì√Ö are thickness & density of the material respectively and A = area normal to the direction of heat flow. )?

*/*_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?

*/*_Overall heat transfer co-efficient of a particular tube is U‚Äö√á√Ö. If the same tube with some dirt deposited on either side has coefficient U‚Äö√á√á, then?

/_The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ≈í√ÆT = Temperature drop across condensate film )?

/_The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m¬¨‚â§. The approximate surface temperature (K) is (Stefan-Boltzman constant = 5.67xl0‚Äö√Ö¬™‚Äö√Ö‚àè W/m¬¨‚â§.K‚Äö√Ö¬•)?

/_Which of the following is concerned with both heat and mass transfer??

/_The film co-efficient between condensing vapour and metal wall increases with?

/_Mode of heat transfer involved in the cooling of air cooled internal combustion engine is?

/_In evaporators, lowering the feed temperature?

/_Which is the most suitable for the con-certration of highly concentrated solution??

/_If h‚Äö√á√Ö = inner film co-efficient and /h‚Äö√á√á = outer film co-efficient, then the overall heat transfer co-efficient is?

/_In forced convection, the Nusselt number is a function of?

/_While the total emissivity of a perfect black body is unity, the same for a real body is?

/_If heat transfer rate varies with the time, it is termed as?

/_The advantage of backward feed multiple effect evaporators over forward feed units is that?

/_A hot body will radiate heat most rapidly, if its surface is?

/_The purpose of providing a 'catchall' in the vapor line of an evaporator is to?

/_Fourier's law applies to the heat transfer by?

/_Kirchoff s law applies to __________ radiation.?

/___________ equation relates the thermal conductivity of a solid to its temperature.?

/_The units of resistance to heat transfer is?

/_Nusselt number is the ratio of the temperature gradient at the wall to?

/_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?

/_Forced circulation evaporators are normally used for concentrating liquids having?

/_A body cools down from 75¬¨‚àûC to 70¬¨‚àûC in 10 minutes. It will cool down from 70¬¨‚àû C to 65¬¨‚àû C in __________ minutes.?

/_Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping?

/_Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is?

/_Crystallisation of solids from a homogeneous solution is a/an __________ process.?

/_Which of the following has the minimum thermal conductivity??

/_In a parallel flow heat exchanger, if the outlet temperature of hot and cold fluids are the same, then the log mean temperature difference (LMTD) is?

/_Mechanical recompression evaporation is used in the production of?

/_Grashoff number, which is defined as g . ≈í‚â§(Ts - T‚Äö√ √ª) ≈ì√Ö¬¨‚â§. L¬¨‚â•/≈í¬∫¬¨‚â§, is proportional to the ratio of buoyancy force to __________ force.?

/_The Stefan-Boltzman constant depends on the?

/_According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor)?

/_Convective heat transfer, in which heat is transferred by movement of warmed matter is described by?

/_For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in?

/_Heat flux, as defined in heat flow is analogous to __________ in electricity flow.?

/_A graph between __________ is called Wilson plot.?

/_Thermal conductivities of most of the liquids __________ with rise in temperature.?

/_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?

/_A 2-4 heat exchanger involves?

/_Terminal point temperature differences between fluids in case of a heat exchanger is termed as?

/_Which of the following has the lowest overall heat transfer co-efficient??

/_With increase in temperature, the thermal conductivity of fresh lubricating oil?

/_The local surface conductance for laminar film condensation on vertical surface is (where, t = film thickness)?

/_A black body when hot, emits heat radiation of __________ wavelengths.?

/_In sub-cooled boiling,?

/_The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe )?

/_Resistance to heat flow by conduction is proportional to (where, t & ≈ì√Ö are thickness & density of the material respectively and A = area normal to the direction of heat flow. )?

/_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?

/_Overall heat transfer co-efficient of a particular tube is U‚Äö√á√Ö. If the same tube with some dirt deposited on either side has coefficient U‚Äö√á√á, then?