Pick out the wrong statement. (A) The controlling resistance in case of heating of air by condensing steam is in the air film (B) The log mean temperature difference (LMTD) for counter flow and parallel flow can be theoretically same when any one of the fluids (hot or cold fluid) passes through the heat exchanger at constant temperature (C) In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply, when a temperature cross occurs (D) Phase change in case of a pure fluid at a given pressure from liquid to vapor or vice-versa occurs at saturation temperature

Pick out the wrong statement.

(A) The controlling resistance in case of heating of air by condensing steam

is in the air film

(B) The log mean temperature difference (LMTD) for counter flow and

parallel flow can be theoretically same when any one of the fluids (hot or cold

fluid) passes through the heat exchanger at constant temperature

(C) In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction

factor value increases sharply, when a temperature cross occurs

(D) Phase change in case of a pure fluid at a given pressure from liquid to

vapor or vice-versa occurs at saturation temperature

by

1 Answer

Answer :

(C) In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction

factor value increases sharply, when a temperature cross occurs

by

Related questions

LMTD for counter-flow and parallel flow heat exchanger will be the same, when the (A) Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid) (B) Outlet temperature of both the hot and cold fluid are same (C) Outlet temperature of hot fluid is less than the outlet temperature of the cold fluid (D) None of these

Description : LMTD for counter-flow and parallel flow heat exchanger will be the same, when the (A) Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid) (B) Outlet temperature of ... temperature of hot fluid is less than the outlet temperature of the cold fluid (D) None of these

Last Answer : (A) Cold fluid is heated to a certain temperature by condensing steam (isothermal fluid)

Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger, the shell pressure drop is maximum for orifice baffles (C) S.I. unit of fouling factor is Watt/m2 .°K (D) Longitudinal fins are used in extended surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Description : Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger ... surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Last Answer : (C) S.I. unit of fouling factor is Watt/m2 .°K

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 (A) 0 (B) 1 (C) > 1 (D) < 1

Description : 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 (A) 0 (B) 1 (C) > 1 (D) < 1

Last Answer : (D) < 1

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

Description : 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

Last Answer : (C) Zero

In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is (A) ∞ (B) 0 (C) Equal to the difference between hot and cold fluids inlet temperature (D) Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature

Description : In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is (A) ∞ (B) 0 ... temperature (D) Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature

Last Answer : (B) 0

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) Higher condensing film co-efficient is desired (B) Condensate is corrosive in nature (C) Lower pressure drop through the exchanger is desired (D) Temperature of the incoming vapor is very high Answer: Option B

Description : 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 ... drop through the exchanger is desired (D) Temperature of the incoming vapor is very high

Last Answer : (B) Supersaturated

Pick out the wrong statement: (A) The capacity of an evaporator is reduced by the boiling point elevation (B) Corrosive liquid is normally passed through the tubes in a shell and tube heat exchanger (C) Steam jet ejector is used for vapor compression in a thermal recompression evaporator (D) Heat sensitive materials should be concentrated in high pressure evaporators

Description : Pick out the wrong statement: (A) The capacity of an evaporator is reduced by the boiling point elevation (B) Corrosive liquid is normally passed through the tubes in a ... recompression evaporator (D) Heat sensitive materials should be concentrated in high pressure evaporators

Last Answer : (D) Heat sensitive materials should be concentrated in high pressure evaporators

LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow 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) Counter flow (D) Same in either 'a', b' or 'c'

Description : LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface ... Parallel (B) Mixed (C) Counter flow (D) Same in either 'a', b' or 'c'

Last Answer : (D) Same in either 'a', b' or 'c'

In a gas-liquid shell and tube heat exchanger, the(A) Presence of a non-condensable gas decreases the condensing film co￾efficient (B) Gases under high pressure are routed through the tube side, because high pressure gases are corrosive in nature (C) Gases to be heated/cooled is normally routed through the shell side, because the corrosion caused by the cooling water or steam condensate remain localised to the tubes (D) All 'a', 'b' & 'c'

Description : In a gas-liquid shell and tube heat exchanger, the (A) Presence of a non-condensable gas decreases the condensing film co￾efficient (B) Gases under high pressure are routed through the tube side, because high pressure ... water or steam condensate remain localised to the tubes (D) All 'a', 'b' & 'c'

Last Answer : (D) All 'a', 'b' & 'c'

Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3 /min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately (A) 32 (B) 37 (C) 45 (D) 50

Description : Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3 /min) of density 800 kg/m3 and specific heat of ... mean temperature difference in °C is approximately (A) 32 (B) 37 (C) 45 (D) 50

Last Answer : (A) 32

Pick out the wrong statement. (A) The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation (B) Film co-efficient for vaporisation decreases as a result of vapor binding (C) In industrial practice, sub-cooling of condensate is required, when thecondensate is a volatile liquid and is to be transferred for storage(D) Overall heat transfer co-efficient in a heat exchanger is controlled by thevalue of the film co-efficient, which is higher

Description : Pick out the wrong statement. (A) The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation ( ... in a heat exchanger is controlled by the value of the film co-efficient, which is higher

Last Answer : (D) Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film co-efficient, which is higher

In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid. (A) Equal to (B) More than (C) Less than (D) Either more or less than (depending upon the fluid)

Description : In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid. (A) Equal to (B) More than (C) Less than (D) Either more or less than (depending upon the fluid)

Last Answer : (A) Equal to

A process stream of dilute aqueous solution flowing at the rate of10 Kg.s -1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s -1 . A 1 - 1 shell and tube heat exchanger is available. The best arrangement is (A) Counter flow with process stream on shell side (B) Counter flow with process stream on tube side (C) Parallel flow with process stream on shell side (D) Parallel flow with process stream on tube side

Description : A process stream of dilute aqueous solution flowing at the rate of10 Kg.s -1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s -1 . A 1 ... side (C) Parallel flow with process stream on shell side (D) Parallel flow with process stream on tube side

Last Answer : (A) Counter flow with process stream on shell side

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

Description : 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

Last Answer : (B) < 0.75

For a multipass shell and tube heat exchanger, the LMTD correction factor is always (A) 1 (B) > 1 (C) < 1 (D) Between 1 & 2

Description : For a multipass shell and tube heat exchanger, the LMTD correction factor is always (A) 1 (B) > 1 (C) < 1 (D) Between 1 & 2

Last Answer : (C) < 1

Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type (A) Parallel flow with equal heat capacities (B) Counter flow with equal heat capacities (C) Counter flow with unequal heat capacities (D) Parallel flow with unequal heat capacities

Description : Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type (A) Parallel flow with equal heat capacities (B) Counter ... (C) Counter flow with unequal heat capacities (D) Parallel flow with unequal heat capacities

Last Answer : (B) Counter flow with equal heat capacities

Pick out the wrong statement. (A) Heat transfer by radiation cannot occur across an absolute volume (B) In case of a shell and tube heat exchanger, the pressure drop through the shell is proportional to the number of times the fluid crosses the bundle between baffles (C) Propagation velocity for travel of heat radiation through vacuum is equal to the velocity of the light (D) The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same

Description : Pick out the wrong statement. (A) Heat transfer by radiation cannot occur across an absolute volume (B) In case of a shell and tube heat exchanger, the pressure drop through the shell is ... The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same

Last Answer : (A) Heat transfer by radiation cannot occur across an absolute volume

In a liquid-liquid heat exchanger, for the same process temperature, the ratio of the LMTD in parallel flow to the LMTD in counter flow is always (A) < 1 (B) > 1 (C) 1 (D) ∞

Description : In a liquid-liquid heat exchanger, for the same process temperature, the ratio of the LMTD in parallel flow to the LMTD in counter flow is always (A) < 1 (B) > 1 (C) 1 (D) ∞

Last Answer : (A) < 1

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

Description : 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

Last Answer : (D) None of these

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 (A) Finned tube heat exchanger with air inside and steam outside (B) Finned tube heat exchanger with air outside and steam inside (C) Shell and tube heat exchanger with air inside tubes and steam on shell side (D) Shell and tube heat exchanger with air on shell side and steam inside tubes

Description : 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 ... steam on shell side (D) Shell and tube heat exchanger with air on shell side and steam inside tubes

Last Answer : (B) Finned tube heat exchanger with air outside and steam inside

In a counter flow heat exchanger, hot fluid enters at 170°C & leaves at 150°C, while the cold fluid enters at 50°C & leaves at 70°C. The arithmetic mean temperature difference in this case is __________ °C. (A) 20 (B) 60 (C) 120 (D) ∞

Description : In a counter flow heat exchanger, hot fluid enters at 170°C & leaves at 150°C, while the cold fluid enters at 50°C & leaves at 70°C. The arithmetic mean temperature difference in this case is __________ °C. (A) 20 (B) 60 (C) 120 (D) ∞

Last Answer : (D) ∞

In a shell and tube heat exchanger, (A) The temperature drops in the two fluids and the wall are proportional to individual resistances (B) The temperature drop is inversely proportional to the resistance across which the drop occurs (C) There is no relationship between temperature drop and resistance (D) The relationship is not generalised

Description : In a shell and tube heat exchanger, (A) The temperature drops in the two fluids and the wall are proportional to individual resistances (B) The temperature drop is inversely proportional to ... ) There is no relationship between temperature drop and resistance (D) The relationship is not generalised

Last Answer : (A) The temperature drops in the two fluids and the wall are proportional to individual resistances

In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid (A) Is inversely proportional to the resistance across which the drop occurs (B) And the wall are proportional to individual resistances (C) And the wall is not related (D) None of these

Description : In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid (A) Is inversely proportional to the resistance across which the drop occurs (B) And the wall are proportional to individual resistances (C) And the wall is not related (D) None of these

Last Answer : (B) And the wall are proportional to individual resistances

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. (A) 2 0.8 (B) 4 0.8 (C) 4 0.4 (D) 2 0.4

Description : 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. (A) 2 0.8 (B) 4 0.8 (C) 4 0.4 (D) 2 0.4

Last Answer : (B) 4 0.8

Correction is applied to LMTD for __________ flow. (A) Parallel (B) Counter (C) Cross (D) None of these

Description : Correction is applied to LMTD for __________ flow. (A) Parallel (B) Counter (C) Cross (D) None of these

Last Answer : (C) Cross

Pick out the wrong statement: (A) Absorption factor is constant, when the equilibrium and operating lines are straight (B) In case of a stripper, the equilibrium curve is always below the operating line (C) In case of an absorber, the operating line is always above the equilibrium curve (D) In the absorption of low solubility gases, the liquid film is the controlling resistance

Description : Pick out the wrong statement: (A) Absorption factor is constant, when the equilibrium and operating lines are straight (B) In case of a stripper, the equilibrium curve is always below ... (D) In the absorption of low solubility gases, the liquid film is the controlling resistance

Last Answer : (B) In case of a stripper, the equilibrium curve is always below the operating line

Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger calculations (Δt) weighted is used in place of Δt, when it involves more than one sequence of heating or cooling i.e., desuperheating & condensation or condensation & sub-cooling (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted (D) In case of short tube vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Description : Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger ... vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Last Answer : (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area (A) Increases (B) Decreases (C) Remain constant (D) Passes through a maxima

Description : For shell and tube heat exchanger, with increasing heat transfer area, the purchased cost per unit heat transfer area (A) Increases (B) Decreases (C) Remain constant (D) Passes through a maxima

Last Answer : (D) Passes through a maxima

Baffles in the shell side of a shell and tube heat exchanger (A) Increase the cross-section of the shell side liquid (B) Force the liquid to flow parallel to the bank (C) Increase the shell side heat transfer co-efficient (D) Decrease the shell side heat transfer co-efficient

Description : Baffles in the shell side of a shell and tube heat exchanger (A) Increase the cross-section of the shell side liquid (B) Force the liquid to flow parallel to the bank (C) Increase the shell side heat transfer co-efficient (D) Decrease the shell side heat transfer co-efficient

Last Answer : (C) Increase the shell side heat transfer co-efficient

If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid (A) Remains unchanged (B) Increases (C) Increases or decreases depending on number of shell passes (D) Decreases

Description : If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid (A) Remains unchanged (B) Increases (C) Increases or decreases depending on number of shell passes (D) Decreases

Last Answer : (D) Decreases

Pick out the wrong statement (A) A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity (B) When water is cooled from 80 to 70°C by exposure to the air with a wet bulb temperature of 60°C, then both the approach & the range would be 10°C (C) For unsaturated air-water vapor mixture at atmospheric conditions, the wet bulb temperature & adiabatic cooling lines are the same (D) Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

Description : Pick out the wrong statement (A) A horizontal line on the humidity chart indicates the temperature changes at constant molal humidity (B) When water is cooled from 80 to 70°C by exposure ... & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

Last Answer : (D) Relative saturation of unsaturated mixture of water vapor & air cannot be increased by either reducing the mixture temperature or by increasing the total pressure

In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid (A) Varies directly as the area and the LMTD (B) Directly proportional to LMTD and inversely proportional to the area (C) Varies as square of the area (D) None of these

Description : In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid (A) Varies directly as the area and the LMTD (B) Directly proportional to LMTD and inversely proportional to the area (C) Varies as square of the area (D) None of these

Last Answer : (A) Varies directly as the area and the LMTD

Pick out the wrong statement about cavitation. (A) Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation (B) Cavitation may be caused due to boiling of liquid by decreasing the pressure resulting in formation & collapse of vapor cavities (C) Cavitation begins at higher static pressure and lower velocity in larger diameter pipelines resulting in audible noise(D) Large scale cavitation cannot damage pipeline, restrict fluid flow anddamage steam turbine blades

Description : Pick out the wrong statement about cavitation. (A) Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation ... (D) Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades

Last Answer : (D) Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades

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 (A) Increase (B) Decrease (C) Remain unchanged (D) Either increase or decrease; depends on the coolant flow rate

Description : 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 ... Decrease (C) Remain unchanged (D) Either increase or decrease; depends on the coolant flow rate

Last Answer : (C) Remain unchanged

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

Description : 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

Last Answer : (C) Both counter and parallel-flow of the fluids

case of condensers & evaporators operating under given terminal conditions, LMTD (logarithmic mean temperature difference) for counter flow as compared to that for parallel flow is (A) More (B) Less (C) Equal (D) Much more

Description : case of condensers & evaporators operating under given terminal conditions, LMTD (logarithmic mean temperature difference) for counter flow as compared to that for parallel flow is (A) More (B) Less (C) Equal (D) Much more

Last Answer : Option C

LMTD can't be used as such without a correction factor for the (A) Multipass heat exchanger (B) Baffled heat exchanger (C) Condensation of mixed vapour in a condenser (D) All (A) (B) and (C)

Description : LMTD can't be used as such without a correction factor for the (A) Multipass heat exchanger (B) Baffled heat exchanger (C) Condensation of mixed vapour in a condenser (D) All (A) (B) and (C)

Last Answer : (D) All (A) (B) and (C)

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 (A) Decreases the pressure drop (B) Decreases the outlet temperature of cooling medium (C) Increases the overall heat transfer coefficient (D) None of these

Description : 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 (A) Decreases the pressure drop (B) ... the outlet temperature of cooling medium (C) Increases the overall heat transfer coefficient (D) None of these

Last Answer : (C) Increases the overall heat transfer coefficient

Extremely large or small volumes of fluids are generally best routed through the shell side of a shell and tube heat exchanger, because of the (A) Less corrosion problems (B) Flexibility possible in the baffle arrangement (C) Low pressure drop (D) High heat transfer co-efficient

Description : Extremely large or small volumes of fluids are generally best routed through the shell side of a shell and tube heat exchanger, because of the (A) Less corrosion problems (B) Flexibility possible in the baffle arrangement (C) Low pressure drop (D) High heat transfer co-efficient

Last Answer : (B) Flexibility possible in the baffle arrangement

For a heat exchanger, will the overall heat transfer coefficient increase along with an increase in LMTD (log mean temperature difference) around the unit?

Description : For a heat exchanger, will the overall heat transfer coefficient increase along with an increase in LMTD (log mean temperature difference) around the unit?

Last Answer : The overall heat transfer coefficient is generally weakly dependent on temperature. As the temperatures of the fluids change, the degree to which the overall heat transfer coefficient will be affected depends ... with temperature as I've noted and the U-value will decrease over time with fouling).

Pick out the wrong statement. (A) Orifice baffles are never used in a shell and tube heat exchanger (B) Pressure drop on the shell side of a heat exchanger depends upon tube pitch also

Description : Pick out the wrong statement. (A) Orifice baffles are never used in a shell and tube heat exchanger (B) Pressure drop on the shell side of a heat exchanger depends upon tube pitch also

Last Answer : (A) Orifice baffles are never used in a shell and tube heat exchanger

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

Description : 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

Last Answer : (A) Approach

Pick out the wrong statement. (A) Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom (B) The heat capacity of solid inorganic substance is exactly equal to the heatcapacity of the substance in the molten state(C) There is an increase in entropy, when a spontaneous change occurs in anisolated system(D) At absolute zero temperature, the heat capacity for many pure crystallinesubstances is zero

Description : Pick out the wrong statement. (A) Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom (B) The heat capacity of solid inorganic substance is exactly equal to the ... isolated system (D) At absolute zero temperature, the heat capacity for many pure crystalline substances is zero

Last Answer : (C) There is an increase in entropy, when a spontaneous change occurs in an isolated system

Pick out the wrong statement. (A) Economy of a multiple effect evaporator is not influenced by the boiling point elevation (B) Two identical cubes of iron and copper will have the same heat content under the same conditions of temperature (C) Double pipe heat exchangers are mostly used in the field of refrigeration (D) Finned tube heat exchangers are suitable for heating air by steam

Description : Pick out the wrong statement. (A) Economy of a multiple effect evaporator is not influenced by the boiling point elevation (B) Two identical cubes of iron and copper will have the same heat ... in the field of refrigeration (D) Finned tube heat exchangers are suitable for heating air by steam

Last Answer : (B) Two identical cubes of iron and copper will have the same heat content under the same conditions of temperature

Vibrations in the tubes of a shell and tube heat exchanger is induced due to the (A) Flow of fluid on the tube and shell sides (B) Oscillations in the flow of shell/tube sides fluid (C) Vibrations transmitted through piping and/or supports due to external reasons (D) All (A), (B) and (C)

Description : Vibrations in the tubes of a shell and tube heat exchanger is induced due to the (A) Flow of fluid on the tube and shell sides (B) Oscillations in the flow of shell/tube sides fluid (C) Vibrations ... piping and/or supports due to external reasons (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Out of the following four assumptions used in the derivation of theequation for LMTD[LMTD = (∆t1- ∆t2)/ln(∆t1/∆t2)], which one is subject to the largest deviationin practice ?(A) Constant overall heat transfer co-efficient.(B) Constant rate of fluid flow(C) Constant specific heat(D) No partial phase change in the system

Description : Out of the following four assumptions used in the derivation of theequation for LMTD [LMTD = (∆t1 - ∆t2 )/ln(∆t1 /∆t2 )], which one is subject to the largest deviation in practice ? (A) Constant ... (B) Constant rate of fluid flow (C) Constant specific heat (D) No partial phase change in the system

Last Answer : (B) Constant rate of fluid flow

Pick out the correct statement about the condensation. (A) Filmwise condensation gives a lower heat transfer rate than the dropwise condensation (B) Suitable coating or vapour additive is used to promote film wise condensation (C) If a condensing liquid does not wet the surface dropwise, even then condensation will take place on it (D) Reynolds number of condensing liquid is based on its mass flow rate

Description : Pick out the correct statement about the condensation. (A) Filmwise condensation gives a lower heat transfer rate than the dropwise condensation (B) Suitable coating or vapour additive is used to promote film ... place on it (D) Reynolds number of condensing liquid is based on its mass flow rate

Last Answer : (B) Suitable coating or vapour additive is used to promote film wise condensation

Dew point of an air-water vapor mixture (A) Decreases with decrease in pressure (B) At constant humidity & total pressure is fixed (C) Corresponding to any point on the humidity chart is obtained by projecting a line through this point parallel to the temperature axis and to the saturation curve (D) All 'a', 'b' & 'c'

Description : Dew point of an air-water vapor mixture (A) Decreases with decrease in pressure (B) At constant humidity & total pressure is fixed (C) Corresponding to any point on the humidity chart is obtained by projecting a ... to the temperature axis and to the saturation curve (D) All 'a', 'b' & 'c'

Last Answer : (D) All 'a', 'b' & 'c'

Pick out the wrong statement. (A) The shear stress at the pipe (dia = D, length = L) wall in case of laminar flow of Newtonian fluids is (D/4L). ∆p (B) In the equation, T. gc = k. (du/dy) n the value of 'n' for pseudoplastic and Dilatant fluid are < 1 and >1 respectively (C) Shear stress for Newtonian fluid is proportional to the rate of shear in the direction perpendicular to motion (D) With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids

Description : Pick out the wrong statement. (A) The shear stress at the pipe (dia = D, length = L) wall in case of laminar flow of Newtonian fluids is (D/4L). ∆p (B) In the equation, T. gc = k. ... to motion (D) With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids

Last Answer : (D) With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids

Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling? (A) Square pitch (B) Triangular pitch (C) Diagonal square pitch

Description : Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling? (A) Square pitch (B) Triangular pitch (C) Diagonal square pitch chemical-engineering

Last Answer : (B) Triangular pitch