Steam is the working fluid in the ideal Rankine cycle 12341

Steam is the working fluid in the ideal Rankine cycle 1-2-3-4-1 and in the Carnot cycle 1-2-3\'-4\'-1 that both operate between pressures of 1.5 bar and 60 bar as shown in the T-s diagram. Both cycles incorporate the steady flow devices. For each cycle determine (a) the net power developed per unit mass of steaming flowing, in kJ/kg, and (b) the thermal efficiency.

Solution

Rankine Cycle:

Net power developed for unit mass = P_1-2 - P_3-4 = (h1-h2) - (h4-h3) = (2784.3-2180.6) -(473.27-467.11) = 603.7- 6.16 =597.54 KJ/kg

Efficiency:

Q1 = h1-h4 = 2784.3 -473.27 =2311.03

Q2 = h2 -h3 = 2180.6-467.11 = 1713.49

Efficiency = (Q1-Q2) / Q1 = (2311.03-1713.49)/2311.03 =597.54/2311.03 = 0.258

Carnot Cycle:

Power for unit mass= (h1-h2) - (h4\'-h3\') = (2784.3-2180.6) -(1213.4-1079.8) = 603.7- 133.6 = 470.1 KJ/kg

Efficiency:

Q1 = h1-h4\' = 2784.3-1213.4= 1570.9

Q2 = h2-h3\' = 2180.6-1079.8 =1100.8

Efficiency = (Q1-Q2) / Q1 = (1570.9-1100.8) / 1570.9 = 470.1/1570.9 = 0.299