ME 3333 Chapter : Homework 13 Solutions
Document Summary
In a brayton cycle the inlet is at 300 k, 100 kpa and the combustion adds 670 kj/kg. The maximum temperature is 1200 k due to material considerations. Find the maximum permissible compression ratio and for that the cycle efficiency using cold air properties. Combustion: h3 = h2 + qh; 2w3 = 0 and tmax = t3 = 1200 k. T2 = t3 - qh/cp = 1200 670/1. 004 = 532. 7 k. Reversible adiabatic compression leads to constant s, from eq. 8. 28: P2 / p1 = (t2/t1) k k-1 = (532. 7/300) Reversible adiabatic expansion leads to constant s, from eq. 8. 28. T4 = t3 (p4/p3) k-1 k = t3 t1/t2 = 1200 300. = wnet / qh = 292. 7 / 670 = 0. 437. Consider an ideal air-standard brayton cycle in which the air into the compressor is at 100 kpa, 20 c, and the pressure ratio across the compressor is 12:1.
