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Heat exchangers - Test
Contributed by: Brennan
  • 1. Which type of heat exchanger uses a set of parallel tubes to transfer heat?
A) Shell and tube
B) Double-pipe
C) Plate
D) Finned tube
  • 2. Which material is commonly used for the construction of heat exchanger tubes?
A) Plastic
B) Copper
C) Aluminum
D) Steel
  • 3. What is used to enhance heat transfer in a heat exchanger by increasing surface area?
A) Fins
B) Gaskets
C) Valves
D) Bearings
  • 4. What is the function of the header in a shell and tube heat exchanger?
A) Reduce pressure
B) Control temperature
C) Distribute the fluid evenly to the tubes
D) Separate hot and cold fluids
  • 5. What is the purpose of the bypass valve in a heat exchanger system?
A) Increase heat transfer
B) Remove air from the system
C) Regulate pressure
D) Control flow rate through the exchanger
  • 6. What is the function of the expansion valve in a refrigeration system?
A) Increase the pressure of the refrigerant
B) Cool the refrigerant
C) Remove moisture from the system
D) Regulate the flow of refrigerant into the evaporator
  • 7. What helps maintain efficient heat transfer by preventing fouling in a heat exchanger?
A) Higher flow rate
B) Regular cleaning and maintenance
C) Less insulation
D) Increased pressure
  • 8. What is meant by the term 'heat exchanger fouling'?
A) Expansion of tube material
B) Decrease in fluid velocity
C) Increase in heat transfer rate
D) Accumulation of deposits on heat transfer surfaces
  • 9. In which flow arrangement do the two fluids enter the exchanger from opposite ends?
A) Cross-flow
B) Counter-flow
C) Parallel-flow
D) Direct-contact
  • 10. What is the driving temperature difference across a heat exchanger surface called?
A) Thermal resistance
B) Net thermal unit (NTU)
C) Log mean temperature difference (LMTD)
D) Heat transfer coefficient
  • 11. Which flow arrangement in heat exchangers involves fluids traveling roughly perpendicular to one another?
A) Direct-contact
B) Parallel-flow
C) Cross-flow
D) Counter-flow
  • 12. What is a common type of shell-and-tube heat exchanger used for cooling air?
A) Evaporator
B) Surface condenser
C) Plate heat exchanger
D) Double-pipe heat exchanger
  • 13. Which of the following is NOT a typical application for shell and tube heat exchangers?
A) Applications requiring robust construction due to high pressure.
B) Processes involving fluids at temperatures greater than 260 °C.
C) High-pressure applications greater than 30 bar.
D) Low-pressure applications with temperatures below 260 °C.
  • 14. What is a critical consideration when determining tube thickness in shell and tube heat exchangers?
A) Reducing the availability of spare parts.
B) Minimizing the axial strength.
C) Ensuring enough room for corrosion resistance.
D) Maximizing the flow-induced vibration.
  • 15. What is the expected annual growth rate of the global demand for heat exchangers?
A) 10% annually.
B) 1% annually.
C) 15% annually.
D) About 5% annually.
  • 16. How can pillow plates be constructed inside a tank?
A) Using flexible rubber sheets
B) Through external attachment
C) As flat plates that are stacked inside a tank
D) By embedding them in concrete
  • 17. Which method for designing helical-coil heat exchangers is from the United States?
A) Boardman-Germer method
B) Laminar flow method
C) Scott S. Haraburda method
D) Ramachandra K. Patil (et al.) method
  • 18. What is the advantage of using U-tubes in shell and tube heat exchangers?
A) They increase the likelihood of fouling.
B) They allow for thermal expansion without stressing the tubesheets.
C) They eliminate the need for baffles.
D) They reduce the overall size of the heat exchanger.
  • 19. What patterns may plates in a plate heat exchanger have?
A) No patterns at all
B) Circular patterns
C) Square grids
D) Chevron, dimpled, or other patterns
  • 20. What is the typical hydraulic diameter of channels in microchannel heat exchangers?
A) Between 1mm and 3mm
B) Larger than 5mm
C) Equal to 10mm
D) Smaller than 1mm
  • 21. In HVAC applications, what is a large plate heat exchanger called?
A) Welded plate variety
B) Circular plate pack
C) Plate-and-frame
D) Shell and tube
  • 22. What is the primary application of a pillow plate heat exchanger in the dairy industry?
A) Fermenting yogurt
B) Heating milk before pasteurization
C) Storing cheese
D) Cooling milk in large direct-expansion stainless steel bulk tanks
  • 23. Which type of direct contact heat exchanger involves heat transfer between gas and liquid?
A) Immiscible liquid – liquid
B) Gas – liquid
C) Microchannel
D) Solid-liquid or solid – gas
  • 24. What is the purpose of the outer shell in a plate and shell heat exchanger?
A) Creates a second flowpath called the 'Shell side'
B) Is used for cleaning purposes
C) Holds the gaskets
D) Contains only the Plate side flowpath
  • 25. Which cycle is typically used in large systems with high volume and temperature gas streams?
A) Organic Rankine cycle (ORC).
B) Steam Rankine cycle (SRC).
C) Phase-change heat exchanger.
D) Dynamic scraped surface heat exchanger.
  • 26. Which of the following is NOT typically used as an organic refrigerant in ORC?
A) Toluene.
B) Pentafluoropropane (R-245fa).
C) Water.
D) Ammonia.
  • 27. Which method for designing helical-coil heat exchangers originates from India?
A) Turbulent flow method
B) Scott S. Haraburda method
C) Boardman-Germer method
D) Ramachandra K. Patil (et al.) method
  • 28. Which industry commonly uses plate and fin heat exchangers for low temperature services?
A) Air separation plants
B) Chemical manufacturing
C) Nuclear power plants
D) Oil refineries
  • 29. In which industry is a pillow plate heat exchanger commonly used?
A) Automotive industry
B) Dairy industry
C) Construction industry
D) Textile industry
  • 30. What material are plate and fin heat exchangers usually made of?
A) Aluminum alloys
B) Stainless steel
C) Titanium
D) Copper
  • 31. What is the primary criterion often considered when selecting a heat exchanger?
A) Color.
B) Size.
C) Shape.
D) Cost.
  • 32. What is a notable tradeoff in heat exchanger design?
A) Capital cost vs operating cost.
B) Material strength vs corrosion resistance.
C) Thermal efficiency vs size.
D) Pressure drop vs fluid velocity.
  • 33. What happens to the thin metal after welding in pillow plate construction?
A) It becomes thinner and more flexible
B) It is removed to create channels
C) It contracts and forms a flat surface
D) It bulges out around the welds when pressurized
  • 34. What is a key characteristic of microchannel heat exchangers compared to finned tube heat exchangers?
A) Higher refrigerant charges
B) Larger size
C) Lower airside pressure drops
D) Less compact
  • 35. What is a potential danger associated with cracked heat exchangers in direct-combustion furnaces?
A) The furnace will produce less heat.
B) Combustion products may enter living space.
C) Airflow will increase significantly.
D) The system will become more energy-efficient.
  • 36. What is a significant concern for HVAC designers regarding water or steam coils?
A) High pressure drops
B) Freeze protection
C) Microchannel design
D) Low refrigerant charges
  • 37. Which tube layout is preferred when high fouling is expected?
A) Rotated square (45°) pattern.
B) Rotated triangular (60°) pattern.
C) Triangular (30°) pattern.
D) Square (90°) pattern.
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