Question

In an ideal rankine cycle. Steam is generated at 4.1 mpa and 480c. The condenser is at 32c. Determine (a) the ideal pump work, (b) the cycle thermal efficiency, (c) for an engine with the same end states, determine its thermal efficiency, steam rate, and mep. (d) considering the engine only, assume the brake engine efficiency to be 78%, the generator efficiency 92%, the steam flow rate is 163,600 kg/hr. Compute the output of the combined unit. Answers: 4.12 kj/kg, 38.66%, 38.73%, 2.85 kg/kwhr 51.92 kpa, 41,227 kw

Answer 1

A most important point to notice is that contrary to a simple Brayton cycle, the thermal efficiency of a Brayton cycle with regeneration decreases with the increase in pressure ratio. Therefore, not all the combinations of pressure and temperature ratios induce an increase in thermal efficiency.