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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) Plate
C) Finned tube
D) Double-pipe
  • 2. Which material is commonly used for the construction of heat exchanger tubes?
A) Copper
B) Aluminum
C) Steel
D) Plastic
  • 3. What is used to enhance heat transfer in a heat exchanger by increasing surface area?
A) Fins
B) Bearings
C) Gaskets
D) Valves
  • 4. What is the function of the header in a shell and tube heat exchanger?
A) Reduce pressure
B) Separate hot and cold fluids
C) Distribute the fluid evenly to the tubes
D) Control temperature
  • 5. What is the purpose of the bypass valve in a heat exchanger system?
A) Regulate pressure
B) Remove air from the system
C) Control flow rate through the exchanger
D) Increase heat transfer
  • 6. What is the function of the expansion valve in a refrigeration system?
A) Increase the pressure of the refrigerant
B) Regulate the flow of refrigerant into the evaporator
C) Remove moisture from the system
D) Cool the refrigerant
  • 7. What helps maintain efficient heat transfer by preventing fouling in a heat exchanger?
A) Increased pressure
B) Less insulation
C) Higher flow rate
D) Regular cleaning and maintenance
  • 8. What is meant by the term 'heat exchanger fouling'?
A) Expansion of tube material
B) Accumulation of deposits on heat transfer surfaces
C) Decrease in fluid velocity
D) Increase in heat transfer rate
  • 9. In which flow arrangement do the two fluids enter the exchanger from opposite ends?
A) Counter-flow
B) Direct-contact
C) Parallel-flow
D) Cross-flow
  • 10. What is the driving temperature difference across a heat exchanger surface called?
A) Log mean temperature difference (LMTD)
B) Net thermal unit (NTU)
C) Heat transfer coefficient
D) Thermal resistance
  • 11. Which flow arrangement in heat exchangers involves fluids traveling roughly perpendicular to one another?
A) Parallel-flow
B) Counter-flow
C) Cross-flow
D) Direct-contact
  • 12. What is a common type of shell-and-tube heat exchanger used for cooling air?
A) Plate heat exchanger
B) Evaporator
C) Double-pipe heat exchanger
D) Surface condenser
  • 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) High-pressure applications greater than 30 bar.
C) Processes involving fluids at temperatures greater than 260 °C.
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) Minimizing the axial strength.
B) Ensuring enough room for corrosion resistance.
C) Maximizing the flow-induced vibration.
D) Reducing the availability of spare parts.
  • 15. What is the expected annual growth rate of the global demand for heat exchangers?
A) About 5% annually.
B) 1% annually.
C) 15% annually.
D) 10% annually.
  • 16. How can pillow plates be constructed inside a tank?
A) Using flexible rubber sheets
B) By embedding them in concrete
C) As flat plates that are stacked inside a tank
D) Through external attachment
  • 17. Which method for designing helical-coil heat exchangers is from the United States?
A) Scott S. Haraburda method
B) Ramachandra K. Patil (et al.) method
C) Boardman-Germer method
D) Laminar flow 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) Chevron, dimpled, or other patterns
B) Square grids
C) Circular patterns
D) No patterns at all
  • 20. What is the typical hydraulic diameter of channels in microchannel heat exchangers?
A) Larger than 5mm
B) Between 1mm and 3mm
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) Plate-and-frame
C) Circular plate pack
D) Shell and tube
  • 22. What is the primary application of a pillow plate heat exchanger in the dairy industry?
A) Heating milk before pasteurization
B) Cooling milk in large direct-expansion stainless steel bulk tanks
C) Fermenting yogurt
D) Storing cheese
  • 23. Which type of direct contact heat exchanger involves heat transfer between gas and liquid?
A) Gas – liquid
B) Solid-liquid or solid – gas
C) Immiscible liquid – liquid
D) Microchannel
  • 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) Contains only the Plate side flowpath
C) Holds the gaskets
D) Is used for cleaning purposes
  • 25. Which cycle is typically used in large systems with high volume and temperature gas streams?
A) Phase-change heat exchanger.
B) Organic Rankine cycle (ORC).
C) Steam Rankine cycle (SRC).
D) Dynamic scraped surface heat exchanger.
  • 26. Which of the following is NOT typically used as an organic refrigerant in ORC?
A) Water.
B) Ammonia.
C) Toluene.
D) Pentafluoropropane (R-245fa).
  • 27. Which method for designing helical-coil heat exchangers originates from India?
A) Turbulent flow method
B) Scott S. Haraburda method
C) Ramachandra K. Patil (et al.) method
D) Boardman-Germer method
  • 28. Which industry commonly uses plate and fin heat exchangers for low temperature services?
A) Chemical manufacturing
B) Oil refineries
C) Air separation plants
D) Nuclear power plants
  • 29. In which industry is a pillow plate heat exchanger commonly used?
A) Dairy industry
B) Automotive 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) Cost.
C) Shape.
D) Size.
  • 32. What is a notable tradeoff in heat exchanger design?
A) Capital cost vs operating cost.
B) Material strength vs corrosion resistance.
C) Pressure drop vs fluid velocity.
D) Thermal efficiency vs size.
  • 33. What happens to the thin metal after welding in pillow plate construction?
A) It becomes thinner and more flexible
B) It contracts and forms a flat surface
C) It bulges out around the welds when pressurized
D) It is removed to create channels
  • 34. What is a key characteristic of microchannel heat exchangers compared to finned tube heat exchangers?
A) Higher refrigerant charges
B) Less compact
C) Larger size
D) Lower airside pressure drops
  • 35. What is a potential danger associated with cracked heat exchangers in direct-combustion furnaces?
A) The furnace will produce less heat.
B) The system will become more energy-efficient.
C) Airflow will increase significantly.
D) Combustion products may enter living space.
  • 36. What is a significant concern for HVAC designers regarding water or steam coils?
A) High pressure drops
B) Low refrigerant charges
C) Freeze protection
D) Microchannel design
  • 37. Which tube layout is preferred when high fouling is expected?
A) Square (90°) pattern.
B) Rotated triangular (60°) pattern.
C) Rotated square (45°) pattern.
D) Triangular (30°) pattern.
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