CPT CPT Heat Transfer & Thermodynamics 1 — Questions and Answers
Question 1: Which mode of heat transfer occurs through direct contact between two solid objects?
- Convection
- Radiation
- Conduction (Correct answer)
- Evaporation
Correct answer: Conduction
Conduction transfers heat through direct molecular contact within or between solid materials without bulk movement of matter.
Question 2: What is the purpose of a heat exchanger in an industrial process system?
- Generate steam for turbines only
- Transfer thermal energy between two fluid streams without mixing them (Correct answer)
- Measure fluid temperature differentials
- Store heat energy for later use
Correct answer: Transfer thermal energy between two fluid streams without mixing them
A heat exchanger allows heat to flow from a hotter fluid to a cooler fluid through a separating wall, controlling process temperatures without the fluids contacting each other.
Question 3: In a shell-and-tube heat exchanger, which fluid typically flows through the tubes?
- The fluid requiring more pressure containment or that is more corrosive (Correct answer)
- The fluid at the lowest pressure only
- The cooling water always
- The fluid with the higher flow rate always
Correct answer: The fluid requiring more pressure containment or that is more corrosive
The tube-side fluid is selected when it requires higher pressure containment, is corrosive (limiting corrosion to tubes rather than the entire shell), or needs easier cleaning access.
Question 4: What does the term 'LMTD' represent in heat exchanger calculations?
- Low Mass Temperature Differential
- Log Mean Temperature Difference (Correct answer)
- Linear Mean Thermal Demand
- Latent Material Transfer Degree
Correct answer: Log Mean Temperature Difference
LMTD (Log Mean Temperature Difference) is the logarithmic average of temperature differences between hot and cold streams at each end, used to calculate heat exchanger duty.
Question 5: A process fluid temperature rises from 60°F to 160°F. What is the temperature rise in degrees Celsius?
- 100°C
- 55.6°C (Correct answer)
- 37.8°C
- 44.4°C
Correct answer: 55.6°C
A 100°F rise equals 100 × 5/9 = 55.6°C rise (temperature differences convert at 5/9 ratio, not using the offset formula).
Question 6: Which thermodynamic law states that energy cannot be created or destroyed, only converted from one form to another?
- Zeroth Law of Thermodynamics
- First Law of Thermodynamics (Correct answer)
- Second Law of Thermodynamics
- Third Law of Thermodynamics
Correct answer: First Law of Thermodynamics
The First Law of Thermodynamics is the principle of conservation of energy, establishing that total energy in a closed system remains constant through transformations.
CPT CPT Heat Transfer & Thermodynamics 1
Which mode of heat transfer occurs through direct contact between two solid objects?