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