HEAT EXCHANGERS MULTIPLE CHOICE QUESTIONS (MCQ) WITH ANSWERS

 

HEAT EXCHANGERS

MULTIPLE CHOICE QUESTIONS

(MCQ) WITH ANSWERS

MCQ are very helpful in complete understanding

and clarity. Fundamentals are easily applied in

practically used heat exchangers.

Fig. Line Diagram of a Parallel Flow Heat Exchanger

Fig. Temperature Variations of Hot & Cold Fluid
in a Parallel Flow Heat Exchanger

Fig. Line Diagram Of a Counter Flow Heat Exchanger
Fig. Temperature Variations of Hot & Cold
Fluids in a Counter Flow Heat Exchanger

 

  1. A heat exchanger transfers heat from one fluid to another
    1. Solid
    2. Fluid
    3. Solid & fluid
    4. None
ANS: (b)
  1. Latent heat is transferred in a heat exchanger during
    1. Heating
    2. Cooling
    3. Phase change
    4. None
ANS: (c )
  1. Sensible heat is transferred in a heat exchanger like
    1. Cooler
    2. Boiler
    3. Condenser
    4. None
(ANS: (a)
  1. In a direct contact heat exchanger, there is
    1. Mass transfer
    2. Heat transfer
    3. Heat & mass transfer
    4. None
ANS: (c )
  1. The direct contact heat exchanger is
    1. Boiler
    2. Condenser
    3. Desert cooler
    4. None
ANS: (c )
  1. In a regenerator heat exchanger
    1. Both hot and cold fluids are passed simultaneously
    2. First hot fluid & then cold fluid is passed
    3. Can’t say
    4. None
ANS: (b)
  1. The operation of a regenerator heat exchanger is
    1. Continuous
    2. Intermittent
    3. Both continuous & intermittent
    4. None
ANS: (b)
  1. In a recuperator heat exchanger, the hot & cold fluids
    1. Mix physically
    2. Do not mix physically
    3. Mix chemically
    4. None
ANS: (b)
  1. Which of the following is the recuperator heat exchanger
    1. Automobile radiator
    2. Desert cooler
    3. Cooling tower
    4. None
ANS: (a)
  1. In a parallel flow heat exchanger, the angle between hot and cold fluids is
(a) 900
(b) 1800
(c ) 00
(d)None
ANS: (c )
  1. In a counter flow heat exchanger, the angle between hot and cold fluids is
  1. (a) 900
  2. (b) 1800
  3. (c ) 00
  4. (d)None
ANS: (b )
  1. In a cross flow heat exchanger, the angle between hot and cold fluids is
(a) 900
(b) 1800
(c ) 00
(d)None
ANS: (a)
  1. In a condenser, the temperature of the hot fluid is
         (a) Decreasing
(b)  Increasing
(c ) Remains constant
(d) None
ANS: (c )
     14. In a condenser, the temperature of the cold fluid is
         (a) Decreasing
  • (b) Increasing
  • (c )Remains constant
  • (d)None
ANS: (b)
      15. In a boiler, the temperature of the hot fluid is
    1. Decreasing
    2. Increasing
    3. Remains constant
    4. None
ANS: (a)
         16. In a boiler, the temperature of the boiling fluid is
    1. Decreasing
    2. Increasing
    3. Remains constant
    4. None
ANS: (c )
       17. Rate of heat transfer by condensing fluid is
  1. m.cp Δt
  2. m. LH
  3. m.Δt
  4. None
ANS (b)
         18. The sequence of the modes of heat transfer in case of a heat exchanger are
  1.  Cond + Conv + rad
  2.  Conv+ Rad +Conv
  3.  Conv +Cond +Conv
  4.  None
      ANS:(c)
        19. The effectiveness of a parallel and counter flow heat exchanger is of same value in a
  1.   Radiator
  2.  Condenser
  3.   Pre-heater
  4.  None
      ANS: (b)
          20. Use a correction factor ‘F’ to calculate the rate of heat transfer in case of a
  1.  Parallel flow heat exchanger
  2.  Counter flow heat exchanger
  3.  Cross flow heat exchanger
  4.  None
      ANS:  (c)
        21. NTU in a heat exchanger is
  1.  UA/C
  2.  C min/UA
  3. UA/C max
  4.  None
      ANS:  (d)
        22. Temperature variation in a heat exchanger is
  1.  Linear
  2.  Parabolic
  3.  Exponential
  4.  None
      ANS: (b)
        23. The heat capacity ratio ‘C’ in a heat exchanger is zero in case of a
  1.  Radiator
  2.  Pre-heater
  3.  Condenser
  4. None
        ANS: (c)
          24. In case of a 1:1 heat exchanger, use
  1.  LMTD
  2.  NTU
  3.   LMTD or NTU
  4.  None
      ANS:  (c)
        25.The equation of LMTD is
  1.  Firstly     (θ1 + θ2)/ ln(θ12)
  2.  Secondly     (θ1 θ2)/ ln(θ12)
  3.  Thirdly     (θ1 –θ2)/ ln(θ12)
  4.  None
        ANS: (c)
         26. ‘C’ heat capacity ratio in a heat exchanger be
  1.  =1
  2.  > 1
  3.  >4
  4.  None
      ANS:  (d)
        27. Heat exchanger effectiveness is
  1.  <1
  2.  =1
  3.  >1
  4.  None
      ANS: (a)
     28. The effectiveness of a parallel flow heat exchanger with increasing value of heat capacity ratio & for a fixed value of NTU
  1. Remains constant
  2. Decreases
  3. Increases
  4. None
      ANS: (b)
        29. The effectiveness of a parallel flow heat exchanger with increasing value of heat capacity ratio & for a fixed value of NTU
  1. Remains constant
  2. Decreases
  3. Increases
  4. None
  5. ANS: (b)
         30. In condensers/boilers, heat capacity ratio is
  1. Infinity
  2. Zero
  3. 1
  4. None
      ANS: (b)
 
      31. The direct contact heat exchanger operate under
  1. Transient conditions
  2. Steady state conditions
  3. Transient/steady state conditions
  4. None
       ANS: (b)
       32. The recuperator heat exchangers operate under
  1. Transient conditions
  2. Steady state conditions
  3. Transient/steady state conditions
  4. None
      ANS: (b)
       33. The regenerator heat exchanger operate under
  1. Transient conditions
  2. Steady state conditions
  3. Transient/steady state conditions
  4. None
       ANS: (a)
      34. When one of the fluids flowing in heat exchanger is of low thermal conductivity, the overall heat transfer coefficient
  1. Decreases
  2. Increases
  3. Remains constant
  4. None
     ANS: (a)
       35. The overall heat transfer coefficient in condensers and boilers is
  1. High
  2. Low
  3. High & low
  4. None
       ANS: (a)
       36. Do we consider the conduction heat transfer in the tube in between the two fluids?
  1. No
  2. Yes
  3. Yes/No
  4. None
       ANS: (a)
        37. The specific heat of hot fluid in a heat exchanger is
  1. Increasing
  2. Decreasing
  3. No change
  4. None
        ANS: (c )
        38. The specific heat of cold fluid in a heat exchanger is
  • (a) Increasing
    (b) Decreasing
    (c )No change
  • (d) None
          ANS; (c )
          39. The overall heat transfer coefficient in a heat exchanger is
  1.  Increasing
  2. Decreasing
  3. No change
  4. None
       ANS: (c )
        40. The correction factor ‘F’ for multi-pass heat exchangers depends on
  1. P +Z
  2. P/Z
  3. P & Z
  4. None
       ANS: (c )
        41. The parameter ‘P’ in a multi-pass heat exchanger is the ratio of 
  1. Rise in temperature of cold fluid and fall of temperature of hot fluid
  2. Fall of temperature of hot fluid to rise of temperature of cold fluid
  3. Rise of temperature of cold fluid to difference between inlet temperatures of hot and cold fluids
  4. None
        ANS: (c )
        42. Factor ‘Z’ in multi-pass heat exchanger is the ratio of
  1. Rise in temperature of cold fluid and fall of temperature of hot fluid
  2. Fall of temperature of hot fluid to rise of temperature of cold fluid
  3. Rise of temperature of cold fluid to difference between inlet temperatures of hot and cold fluids
  4. None
       ANS: (b )
          43. The change in correction factor ‘F’ with the increasing value of parameter ’Z’ at a fixed value of parameter ‘P’
  1. Constant
  2. Increases
  3. Decreases
  4. None
       ANS: (b)
        44. The change in correction factor ‘F’ with the increasing value of parameter ’P’ at a fixed value of parameter ‘Z’
  1. Constant
  2. Increases
  3. Decreases
  4. None
        ANS: (c). 
     45. Overall heat transfer coefficient is associated with
(a) Conduction
(b) Convection
(c) Radiation
(d) None
(Ans: d)
     46. Overall heat transfer coefficient is associated with
(a) Conduction and radiation
(b) Convection and radiation
(c) Radiation, convection and conduction
(d) None
(Ans: d)
       47. Overall heat transfer coefficient is associated with
(a) Conduction and radiation
(b) Convection and conduction
(c) Radiation and convection
(d) None
(Ans: b)
       48. Thermal contact resistance in conduction heat transfer is due to
(a) Polished surfaces in contact
(b) Rough surfaces in contact
(c) Smooth surfaces in contact
(d) None
(Ans: b)
    49. Thermal contact resistance decreases the temperature
(a) Linearly
(b) Parabolic
(c) Instantaneously
(d) None
(Ans: c)
      50. Conduction heat flux is
(a) -k A dt/dx
(b) -k dt/dx
(c) +k A dt/dx
(d) None
(Ans: b)
      51. Convective heat flux is
(a) h A dt
(b) h A
(c) h dt
(d) None
(Ans: c)
      52. Radiation heat flux is
(a) σ A T4
(b) σ A dT
(c) σ T4
(d) None
(Ans: c)
   53. The expression for overall heat transfer coefficient for a single wall construction is
(a) 1/U = 1/hi + x/k + 1/ho
(b) 1/UA = 1/hi Ai + x/kA + 1/ho Ao
(c) 1/UA = 1/hi Ao + x/kA + 1/ho Ai
(d) None
(Ans: a)
    54. Temperature variation in a pipe is
(a) linear
(b) Parabolic
(c) logarithmic
(d) None
(Ans: c)
55. Temperature variation in a plain wall is
(a) linear
(b) Parabolic
(c) logarithmic
(d) None
(Ans: a)
56. The effectiveness of a parallel and counter flow heat exchanger is of same value
(a) in a radiator
(b) In a Condenser
(c) in a Pre-heater
(d) None
ANS: (b)

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