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+clear;

+clc;

+disp('Example 10.8');

+

+//  aim : To determine

+//  (a) the rankine fficiency

+//  (b) the specific steam consumption

+//  (c) the carnot efficiency of the cycle

+

+// given values

+P1 = 1100;// steam entering pressure, [kN/m^2]

+T1 = 273+250;// steam entering temperature, [K]

+P2 = 280;// pressure at point 2, [kN/m^2]

+P3 = 35;// pressure at point 3, [kN/m^2]

+

+// solution

+// (a)

+// from steam table, at P1  and T1 is

+hf1 = 2943;// [kJ/kg]

+hg1 = 2902;// [kJ/kg]

+h1 = hf1-.1*(hf1-hg1); // [kJ/kg]

+

+sf1 = 6.926;// [kJ/kg K]

+sg1 = 6.545;// [kJ/kg K]

+s1 = sf1-.1*(sf1-sg1);// [kJ/kg K]

+

+// at P2

+sf2 = 1.647;// [kJ/kg K] 

+ sg2 = 7.014;// [kJ/kg K]

+// s2=sf2+x2(sg2-sf2)

+// since expansion through turbine is isentropic so s1=s2

+ // hence

+ s2  = s1;

+ x2 = (s2-sf2)/(sg2-sf2);// dryness fraction

+ 

+ // at point 2

+ hf2 = 551.4;// [kJ/kg]

+ hfg2 = 2170.1;// [kJ/kg]

+ h2 = hf2+x2*hfg2;// [kJ/kg]

+ vg2 = .646;// [m^3/kg]

+ v2 = x2*vg2;// [m^3/kg]

+ 

+ // by Fig10.20.

+ A6125 = h1-h2;// area of 6125, [kJ/kg]

+ A5234 = v2*(P2-P3);// area 5234, [kJ/kg]

+ W = A6125+A5234;// work done 

+ hf = 304.3;// specific enthalpy of water at condenser pressuer, [kJ/kg]

+ ER = h1-hf;// energy received, [kJ/kg]

+ Re = W/ER;// rankine efficiency

+ mprintf('\n (a) The rankine efficiency is  =  %f percent\n',Re*100);

+ 

+ // (b)

+ kWh = 3600;// [kJ]

+ SSC = kWh/W;// specific steam consumption, [kJ/kWh]

+ mprintf('\n (b) The specific steam consumption is = %f kJ/kWh\n',SSC);

+ 

+ // (c)

+ // from steam table 

+T3 = 273+72.7;// temperature at point 3

+CE = (T1-T3)/T1;// carnot efficiency

+mprintf('\n (c) The carnot efficiency of the cycle is  =  %f percent\n',CE*100);

+

+//  End