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04-BS-10: December 2014

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

  1. Question 1 Reheat Rankine Cycle — Non-Ideal Turbines and Pump, with Second-Law Efficiency
  2. Question 2 Air-Standard Brayton Cycle — Two-Stage Turbine with Reheat, Variable Specific Heats
  3. Question 3 R-134a Heat Pump Driven by a Power Cycle
  4. Question 4 Air Conditioner — Cooling and Dehumidification of Moist Air
  5. Question 5 O₂/N₂ Ideal-Gas Mixture — Constant-Pressure Heating
  6. Question 6 R-134a — Entropy Change and Feasibility of an Adiabatic Process
  7. Question 7 Adiabatic Mixing Chamber — Hot and Cold Water Streams
  8. Question 8 Ideal Otto Cycle — Variable Specific Heats
  9. Question 9 R-134a Refrigerator — Non-Ideal Compressor with a Suction-Line Pressure Drop

Start with Question 1 →

National Exam 04-BS-10, Thermodynamics — December 2014. 3 hours, Closed-Book Exam (approved calculator and one double-sided 8.5x11-inch aid sheet permitted; property tables and charts supplied in an appendix). Part A: answer 2 of Questions 1-3 (20 marks each). Part B: answer 4 of Questions 4-9 (15 marks each), for a 100-mark paper. Only the first two Part-A and first four Part-B questions as they appear in the answer book are marked. All nine questions (Part A complete, Part B complete) are solved below for completeness.

Reference texts: Cengel & Boles, Thermodynamics: An Engineering Approach, 8th ed.; Moran, Shapiro, Boettner & Bailey, Fundamentals of Engineering Thermodynamics, 8th ed. State properties for the real-fluid questions (R-134a, water/steam, moist air, air) were computed from high-accuracy equations of state in place of printed property-table interpolation. Question 5 is the exception: it directs that the mixture be treated as an ideal gas, so its N₂ and O₂ enthalpies are taken from the ideal-gas tables supplied with the paper.