Analysis of a Rankine Cycle Power Plant
Michael Piller, Michael Kellner
Thermodynamics Final Project
Prof. Jose Roberto Lopez
Franciscan University of Steubenville
5/4/2026
Introduction:
The Rankine cycle is a thermodynamic cycle used to convert heat into mechanical work. It operates in a closed
loop using a working fluid (typically water/steam) and is mainly used for electric power generation.
The main components of a Rankine cycle and their functions are as follows:




Boiler
o Heat is added at (ideally) constant pressure and liquid water is converted into high-pressure, high
temperature steam.
Turbine
o The steam expands through the turbine, turning it to create mechanical shaft work. This is the
primary work output of the cycle.
Condenser
o The exhaust steam from the turbine is condensed back into a saturated liquid at low pressure by
rejecting heat into a cooling medium, typically a river or air.
Pump
o The liquid is repressurized back to the boiler pressure and requires work. This work is relatively
small compared to the work output from the shaft.
(Figure provided by sciencedirect.com)
The ideal process works like this:
1 to 2: Isentropic pumping (compressing the liquid)
2 to 3: Constant pressure heat addition (from the boiler)
3 to 4: Isentropic expansion (Steam spins the turbine)
4 to 1: Constant pressure heat rejection (steam is cooled back to a liquid)
However, the real process is different from the ideal process. First the ideal process assumes the turbine and
pump are isentropic, however this is not often the case. Second, the ideal process assumes there is no pressure
loss in the pipes, boiler, or condenser, which is not the case and the pressure drop reduces efficiency. Lastly, the
ideal process assumes heat transfer is totally reversible, however in the real process this is not the case due to
imperfect insulation.
Below are diagrams of the idealized Rankine cycle.
(Figures provided by mechstudies.com)
The governing equations of the Rankine cycle are as follows
Work done by the turbine:
𝑊
=ℎ −ℎ
Heat added by the boiler
𝑄
=ℎ −ℎ
Work done on the pump:
𝑊
=ℎ −ℎ
𝑄
=ℎ −ℎ
Heat removed by condenser
Net work:
𝑊
=𝑊
−𝑊
Thermal Efficiency:
𝑛
=
𝑊
𝑄
Power output (also mass flow relation):
Ẇ
= ṁ(𝑊
−𝑊
)
Real world applications of the Rankine cycle include coal fired and nuclear power plants. In coal fired plants
burn pulverized coal in a furnace to heat the boiler. They often include regenerative feedwater heating to
improve efficiency and have an efficiency rating from 35 to 45%. The advantages of the technology include that
is reliable and has a high-power output capability, however downsides include concerns about CO2 emissions,
and the thermal efficiency is limited by material constraints and heat losses.
In nuclear powerplants, a nuclear reactor generates heat via fission reactions, and the heat is directly transferred
to the working fluid. It has slightly lower thermal efficiency at around 30 to 35%, however it is an extremely
reliable technology. Advantages include no direct CO2 emissions, and the fuel has a high energy density.
However, some disadvantages include a high capital cost, and the disposal of nuclear waste is difficult and
requires extra safety precautions and protocols.
Using EES, we calculate the heat added and lost, the work done by the turbine, the work on the pump, the net
work produced from the system, and the thermal efficiency.
Then we use EES to generate PV and Ts diagrams of this cycle, as well as plots, as seen below.
Temperature-entropy (T-s) diagram of the ideal Rankine cycle at boiler pressure of 8 MPa, condenser pressure
of 10 kPa, and turbine inlet temperature of 480°C. The pump causes a very small temperature increase in the
liquid water. On a scale that goes from 0°C to 700°C, the jump from State 1 (condenser exit) to State 2 (boiler
inlet) is so minuscule that the two points overlap. This makes the bottom-left corner look like a single point,
seemingly hiding the vertical line that represents the pump's work.
If you were to zoom in significantly on that bottom left corner of what looks like a triangle, you would see two
points – one at the saturated liquid line (State 1) and one slightly above it (State 2). The "missing" fourth point
is simply buried in that blue square at the bottom left.
Pressure-specific volume (P-v) diagram of the ideal Rankine cycle at boiler pressure of 8 MPa, condenser
pressure of 10 kPa, and turbine inlet temperature of 480°C.
To further understand the influence of key operating parameters on the performance of the ideal Rankine cycle,
a parametric analysis was conducted using EES. The effects of three important variables were investigated
while keeping the other two parameters at their base case values (boiler pressure = 8 MPa, condenser pressure =
10 kPa, and turbine inlet temperature = 480°C):

Boiler pressure varied from 4 MPa to 16 MPa

Condenser pressure varied from 5 kPa to 20 kPa

Turbine inlet temperature varied from 400°C to 600°C
For each case, the net work output and thermal efficiency were calculated and plotted. The results are presented
below along with a discussion of the observed trends, seen below.
Variation of net work output with boiler pressure for the ideal Rankine cycle (T_turbine = 480°C, P_condenser
= 10 kPa).
Thermal efficiency as a function of boiler pressure for the ideal Rankine cycle (T_turbine = 480°C,
P_condenser = 10 kPa).
Variation of net work output with condenser pressure for the ideal Rankine cycle (P_boiler = 8 MPa, T_turbine
= 480°C).
Thermal efficiency as a function of condenser pressure for the ideal Rankine cycle (P_boiler = 8 MPa,
T_turbine = 480°C).
Variation of net work output with turbine inlet temperature for the ideal Rankine cycle (P_boiler = 8 MPa,
P_condenser = 10 kPa).
Thermal efficiency as a function of turbine inlet temperature for the ideal Rankine cycle (P_boiler = 8 MPa,
P_condenser = 10 kPa).
These tables present the results used to make plots through the parametric analysis performed on the ideal
Rankine cycle using 10 data points for each variable (instead of the minimum 4) to better capture the trends.
The effect of boiler pressure, condenser pressure, and turbine inlet temperature on net work output and thermal
efficiency was evaluated while holding the other parameters constant at the base case values.
Discussion
Conducting a parametric study shows how adjusting boiler and condenser conditions directly impacts the
Rankine cycle's thermal efficiency and work output. Increasing the boiler pressure and turbine inlet temperature
improves performance by raising the average temperature of heat addition, which aligns with learned principles
to maximize energy conversion. In the other hand, increasing condenser pressure reduces efficiency because it
raises the heat rejection temperature, hence narrowing the cycle's work potential. While this ideal analysis
provides a clear performance baseline, it is limited by neglecting real world factors such as fluid friction,
pressure drops in piping, and other isentropic inefficiencies of actual pumps and turbines. To enhance
performance in practical applications, a good engineer would implement reheating to increase steam quality or
regeneration to pre heat feedwater, both of which would improve the overall efficiency of the cycle.
Conclusion
Our analysis effectively used Engineering Equation Solver to evaluate a Rankine cycle operating at 8 MPa and
480°C. The results confirm that cycle performance depends on pressure and temperature, with the highest
efficiencies achieved by maximizing the temperature of heat addition while minimizing condenser pressure as
seen in the parametric study plots. Though this kind of idea model does not account for mechanical losses and
material constraints, it successfully demonstrates the fundamental principles regarding steam power plants. In
the end, the study shows how optimizations like reheating and regeneration are essential for advancing the
efficiency of effective power generation systems.
Citations:
https://www.mechstudies.com/rankine-cycle-actual-diagrams-equations-formula/
https://www.sciencedirect.com/topics/engineering/steam-rankine-cycle
EES Code:
P_boiler = 8000 [kPa]
P_cond = 10 [kPa]
T_turb = 480 [C]
"State 1 - Saturated liquid at condenser pressure"
P[1] = P_cond
x[1] = 0
h[1] = Enthalpy(Water, P=P[1], x=x[1])
s[1] = Entropy(Water, P=P[1], x=x[1])
v[1] = Volume(Water, P=P[1], x=x[1])
"State 2 - Pump outlet (isentropic compression)"
P[2] = P_boiler
s[2] = s[1]
h[2] = Enthalpy(Water, P=P[2], s=s[2])
T[2] = Temperature(Water, P=P[2], h=h[2])
"State 3 - Boiler outlet (superheated vapor)"
P[3] = P_boiler
T[3] = T_turb
h[3] = Enthalpy(Water, T=T[3], P=P[3])
s[3] = Entropy(Water, T=T[3], P=P[3])
"State 4 - Turbine outlet (isentropic expansion)"
P[4] = P_cond
s[4] = s[3]
h[4] = Enthalpy(Water, P=P[4], s=s[4])
T[4] = Temperature(Water, P=P[4], h=h[4])
"Energy Analysis"
w_turbine = h[3] - h[4]
"[kJ/kg]"
w_pump = h[2] - h[1]
"[kJ/kg]"
w_net = w_turbine - w_pump "[kJ/kg]"
Q_in = h[3] - h[2]
"[kJ/kg]"
Q_out = h[4] - h[1]
"[kJ/kg]"
n_th = (w_net / Q_in) * 100 "[%]"