Question 11.CSGP.180a: Do Problem 11.21 with R-22 as the working fluid. A supply of......

Fundamentals of Thermodynamics – Solution Manual [1477300]

Do Problem 11.21 with R-22 as the working fluid.
A supply of geothermal hot water is to be used as the energy source in an ideal Rankine cycle, with R-134a as the cycle working fluid. Saturated vapor R-134a leaves the boiler at a temperature of 85°C, and the condenser temperature is 40°C. Calculate the thermal efficiency of this cycle.

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CV: Pump (use R-22 Computer Table)

\begin{aligned}& w _{ P }= h _2- h _1=\int_1^2 vdP \approx v _1\left( P _2- P _1\right)=0.000884(4037-1534)=2.21 \,kJ / kg \\& h _2= h _1+ w _{ P }=94.27+2.21=96.48\, kJ / kg\end{aligned}

CV: Boiler: $q _{ H }= h _3- h _2=253.69-96.48=157.21 \,kJ / kg$

CV: Turbine

\begin{aligned}& s _4= s _3=0.7918=0.3417+ x _4 \times 0.5329, \Rightarrow \quad x _4=0.8446 \\& h _4=94.27+0.8446 \times 166.88=235.22 \,kJ / kg \\& w _{ T }= h _3- h _4=253.69-235.22=18.47 \,kJ / kg \\& \eta_{ TH }= w _{ NET } / q _{ H }=(18.47-2.21) / 157.21= 0 . 1 0 3 4\end{aligned}

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