Question

a ✓ 8.39 8.32 An ideal Rankine cycle with reheat uses water as the working fluid. The conditions at the inlet to the first-stage turbine are pı = 16 MPa, T = 520°C. The steam is reheated at constant pressure p between the turbine stages to 520°C. The condenser pressure is 6 kPa. (a) If p/pı = 0.4, determine the cycle thermal efficiency and the steam quality at the exit of the second-stage turbine. (b) Plot the quantities of part (a) versus the pressure ratio p/p, ranging from 0.04 to 1.0. in worlringon Bonline cycle with 840

principles of engineering thermodynamics SI version,8th edition
Moran,shapiro

Answer 1

{initial state, (first stage turbine inlet)} p1=16000 t1 =520 h1=enthalpy(water,p=p1,t=t1) s1=entropy(water, p=p1,t=t1) pressure_ratio=0.4 {state2 (turbine exit/reheater inlet)} p2= pressure_ratio*p1 s2=s1 {isoentropic expansion} h2= enthalpy(water.p=p2.s=s2) {state3 (reheater exit/ second turbine inlet)} p3=p2 t3=520 h3=enthalpy water,p=p3.t=t3) s3=entropy(water.p=p3t=t3) {state4 (condensor inlet)} p4=6 S4=s3 {isoentropic expansion} h4 =enthalpy(water,p=p4.s=s4) s4-entropy(waterp-p4.x=0) {entropy of saturate liquid a 6KPa} s4g-entropy(water.p=p4,x=1) {entropy of sturated vapour at 6 kPa) {state5(condensor exit)} p5=p4 h5= enthalpy(water.p=p5.x=0) V5= volume(water, p-p5,x=0) {state6 (pump exit)} p6=p1 16=15+(v5*{p6-p5)) {calculation) effiency=(((h1-12)+(h3-14)-(h6-h5))/((h1-16)+(h3-h2))) {effency=(net work out put)/ (net heat input)} quality= (s4-s41)/(s4g-s41)

Unit Settings: SIC kPa kJ mass deg effiency = 0.4459 h1 = 3354 [kJ/kg] p2 = 6400 [KPa] p3 = 6400 [KPa] $2 = 6.376 [KJ/kg-K] s3 = 6.907 [kJ/kg-K] h2 = 3087 [kJ/kg] p4 = 6 [KPa] s4 = 6.907 [KJ/kg-K] h3 = 3465 [kJ/kg] p5 = 6 [KPa] s4g = 8.328 [kJ/kg-K] h4 = 2127 [kJ/kg] p6 = 16000 [KPa] 541 = 0.5208 [kJ/kg-K] h5 = 151.5 [kJ/kg] pressure ratio = 0.4 t1 = 520 [c] h6 - 167.6 [KJ/kg] quality = 0.818 t3 = 520 [c] p1 = 16000 [KPa] s1 = 6.376 [KJ/kg-K] v5 = 0.001006 [m3/kg] No unit problems were detected. EES suggested units (shown in purple) for h1 h2 h3 h4 h5 h6 Calculation time = 0 sec.

0.45 0.445 effiency 0.435. 0.43 0.2 0.8 0.4 0.6 pressureratio

quality 7L11 O 0.2 0.8 0.4 0.6 pressureratio