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MCQs

Total Questions : 65 | Page 2 of 7 pages
Question 11. Hot water having specific heat 4200 J/kg K flows through a heat exchanger at the rate of 4 kg/min with an inlet temperature of 100 degree Celsius. A cold fluid having a specific heat 2400 J/kg K flows in at a rate of 8 kg/min and with inlet temperature 20 degree Celsius. Make calculations for maximum possible effectiveness if the fluid flow conforms to parallel flow arrangement
  1.    0.533
  2.    0.633
  3.    0.733
  4.    1
 Discuss Question
Answer: Option A. -> 0.533
Answer: (a).0.533
Question 12. Assumptions made for calculation of logarithmic mean temperature difference are
(i) Constant overall heat transfer coefficient
(ii) The kinetic and potential energy changes are negligible
(iii) There is no conduction of heat along the tubes of heat exchanger
Identify the correct statements
  1.    1, 2 and 3
  2.    1 and 3
  3.    1 and 2
  4.    2 and 3
 Discuss Question
Answer: Option A. -> 1, 2 and 3
Answer: (a).1, 2 and 3
Question 13. In a food processing plant, a brine solution is heated from – 12 degree Celsius to – 65 degree Celsius in a double pipe parallel flow heat exchanger by water entering at 35 degree Celsius and leaving at 20.5 degree Celsius. Let the rate of flow is 9 kg/min. Estimate the area of heat exchanger for an overall heat transfer coefficient of 860 W/m² K. For water c P = 4.186 * 10³ J/kg K
  1.    1. 293 m²
  2.    0.293 m²
  3.    7. 293 m²
  4.    8. 293 m²
 Discuss Question
Answer: Option B. -> 0.293 m²
Answer: (b).0.293 m²
Question 14. A cold fluid (specific heat 2.95 k J/kg K) at 10 kg/min is to be heated from 25 degree Celsius to 55 degree Celsius in a heat exchanger. The task is accomplished by extracting heat from hot water (specific heat 4.186 k J /kg K) available at mass flow rate 5 kg/min and inlet temperature 85 degree Celsius. Identify the type of arrangement of the heat exchanger
  1.    Concentric tubes
  2.    Parallel flow
  3.    Counter flow
  4.    Shell and tubes
 Discuss Question
Answer: Option C. -> Counter flow
Answer: (c).Counter flow
Question 15. A counter flow heat exchanger is used to col 2000 kg/hr of oil (c p = 2.5 k J/kg K) from 105 degree Celsius to 30 degree Celsius by the use of water entering at 15 degree Celsius. If the overall heat transfer coefficient is expected to be 1.5 k W/m² K, find out the water flow rate. Presume that the exit temperature of the water is not to exceed 80 degree Celsius
  1.    1680.2 kg/hr
  2.    1580.2 kg/hr
  3.    1480.2 kg/hr
  4.    1380.2 kg/hr
 Discuss Question
Answer: Option D. -> 1380.2 kg/hr
Answer: (d).1380.2 kg/hr
Question 16. Which one is having lowest value of specific heat?
  1.    Coal
  2.    Clay
  3.    Banana
  4.    Concrete
 Discuss Question
Answer: Option D. -> Concrete
Answer: (d).Concrete
Question 17. Which one is having highest value of overall heat transfer coefficient?
  1.    Steam condensers
  2.    Feed water heaters
  3.    Alcohol condensers
  4.    Steam
 Discuss Question
Answer: Option B. -> Feed water heaters
Answer: (b).Feed water heaters
Question 18. What is the value of specific heat for coal in J/kg K?
  1.    1260
  2.    1360
  3.    1460
  4.    1560
 Discuss Question
Answer: Option A. -> 1260
Answer: (a).1260
Question 19. What is the value of specific heat for cotton in J/kg K?
  1.    1600
  2.    1500
  3.    1400
  4.    1300
 Discuss Question
Answer: Option D. -> 1300
Answer: (d).1300
Question 20. What is the value of specific heat for sand in J/kg K?
  1.    800
  2.    700
  3.    600
  4.    500
 Discuss Question
Answer: Option A. -> 800
Answer: (a).800

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