Engineering Board Exam Reviewer · Thermodynamics · medium

What is the maximum possible efficiency of a heat engine operating between 800 K and 300 K?

  1. 37.50%
  2. 166.67%
  3. 100.00%
  4. 62.50%

Answer

D. 62.50%

Solution

ηCarnot = 1 - TL/TH = 1 - 300/800 = 62.50%.

More Thermodynamics questions

  1. 1000 kJ of heat is transferred directly from a reservoir at 600 K to a reservoir at 300 K. What is the total entropy generated?
  2. Air changes from 100 kPa, 300 K to 500 kPa, 500 K. What is the change in specific entropy? (cp = 1.0 kJ/kg· K, R = 0.287 kJ/kg· K)
  3. One kilogram of air expands isothermally to three times its initial volume. What is the change in entropy? (R = 0.287 kJ/kg· K)
  4. One kilogram of water is heated from 300 K to 350 K. What is its change in entropy? (c = 4.187 kJ/kg· K)
  5. A system receives 500 kJ of heat reversibly at a constant temperature of 400 K. What is its change in entropy?
  6. One kilogram of air is heated at constant pressure from 300 K to 600 K. What is the change in entropy? (cp = 1.0 kJ/kg· K)
  7. For the same pressure ratio and initial state, which compression process requires the LEAST work in a steady-flow compressor?
  8. In a constant-pressure process of a closed system, the heat transferred is equal to the change in:
  9. In a constant-volume process, the heat transferred is equal to the change in:
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