22-Mec-B3 Energy Conversion and Power Generation, December 2013: worked solutions

Paper format: 07-Mec-B3 Energy Conversion and Power Generation, December 2013 — three hours, closed book. Two sections: Section A (Calculative) Questions 1–4 and Section B (Descriptive) Questions 5–6. Candidates do three from Section A and one from Section B; four questions constitute a complete paper (total 60 marks, each question 15 marks). Reference data are bound into the paper on pages 8–11 and reference formulae and constants on pages 12–15; steam tables from Thermodynamics and Heat Power are provided. All six printed questions are solved below, because the set as a whole is the study resource.

Reference texts for this subject

Granet & Bluestein, Thermodynamics and Heat Power, 6th ed. — the steam tables and Mollier chart issued with this paper; vapour-cycle and turbine chapters.
El-Wakil, Powerplant Technology — heat balance diagrams, regenerative feedheating, combined cycles, condensers and cooling water, environmental impact of generation.
Çengel & Boles, Thermodynamics: An Engineering Approach, 9th ed. — Brayton and Rankine cycle analysis, cycle modifications, jet-propulsion cycles.
Lamarsh & Baratta, Introduction to Nuclear Engineering, 4th ed. — CANDU heat transport and reactor heat removal.
Rayaprolu, Boilers for Power and Process — furnace and boiler efficiency accounting, stack losses.

Note on the page-8 heat balance diagram (Question 2). The printed diagram shows no unaccounted loss at the high-pressure turbine: the two gland leak-off streams on the seal header (4.9 kg/s and 0.1 kg/s) close the balance exactly, \(475.1 + 31.9 + 1.2 + 0.9 + 4.9 + 0.1 = 514.1\) kg/s. The one genuine misprint on the diagram is the feed-pump suction label “9.56 h”, which its own neighbours force to be 956 kJ/kg (979 − Δh 23 = 956, and \(h_f\) at the stated 223 °C is 956 kJ/kg).

22-Mec-B3 Energy Conversion and Power Generation: December 2013