Consider the situation described in Problem 9.74, but now neither the compressor nor the turbine is ideal. Assume that the isentropic efficiency of the compressor is 0.82 and the isentropic efficiency of the turbine is 0.87.

A. Sketch the cycle on T–s and P–v diagrams indicting the key state points with bold dots. Show both the isentropic and actual state points for conditions at the compressor and turbine outlets.

B. Calculate the heat added per unit mass, q₂–₃, the net work per unit mass, wnet, and the thermal efficiency ηth as functions of the compressor pressure ratio for a range from 10 to 25. Also calculate the ratio of the cycle thermal efficiency to the ideal cycle thermal efficiency for the same pressure ratio. Create a single computer-generated plot of your results.

C. Discuss your results and compare them with the results of Problem 9.74. Use additional graphs as necessary.

Data from in Problem 9.74

Consider the same situation described in Problem 9.73, but now the turbine inlet temperature is a given quantity (T₃ = 1700 K) and the heat added per unit mass, q₂–₃, is unknown.

Data from in Problem 9.73

Transcribed Image Text:

Consider an ideal air-standard Brayton cycle operating with inlet temperature (T) and pressure (P) of 300 K and 100 kPa, respectively. The heat added per unit mass, 92-3, is 1050 kJ/kg. Assume the following constant values of the specific heats: cp = 1.005 kJ/kg-K and c = 0.718 kJ/kg.K. Investigate the effects of the compressor pressure ratio (P/P) by performing the tasks listed. Use a spreadsheet to perform all repetitive calculations; however, make sure that you check at least one calculation by hand.