(a) Steam at 20 bar and 375 °C expands reversibly in a perfectly thermally insulated cylinder behind a piston until the pressure is 0.35 bar. Sketch the p-v and T-s diagrams for the process and calculate the work done per kilogram of steam for this process. (b) If the process in 3 (a) takes place in a steam turbine which is also perfectly thermally insulated, calculate the work done per kilogram of steam and the mass flow rate of steam for the turbine to develop a power output of 1600 kW. (c) How will the results for Part (a) and Part (b) compare with that for actual processes, explain the reason for any difference and the effect on the steam mass flow rate to produce the same power output in Part (b) for the actual process.
(a) Steam at 20 bar and 375 °C expands reversibly in a perfectly thermally insulated cylinder behind a piston until the pressure is 0.35 bar. Sketch the p-v and T-s diagrams for the process and calculate the work done per kilogram of steam for this process.
(b) If the process in 3 (a) takes place in a steam turbine which is also perfectly thermally insulated, calculate the work done per kilogram of steam and the mass flow rate of steam for the turbine to develop a power output of 1600 kW.
(c) How will the results for Part (a) and Part (b) compare with that for actual processes, explain the reason for any difference and the effect on the steam mass flow rate to produce the same power output in Part (b) for the actual process.
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