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Maximize the Efficiency of a Rankine Cycle

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Maximizing the Efficiency of a Regenerative Rankine Cycle


Rankine cycles are a thermodynamic process that turn heat into mechanical work. They're often employed in generating electrical power, with high pressure steam used to rotate a turbine.

The thermodynamic efficiency of a Rankine cycle is  "eta= `W__net`/(Q),"where W__net is the net work done by the system, and Q is the heat added. Operating parameters are chosen to maximize efficiency - these may be the temperatures or pressures at various points in the system.


A typical regenerative Rankine cycle is illustrated below.



In this application, we will



define a procedure that calculates the cycle efficiency as a function of the pump outlet pressures at points 2 and 4


and then find the pump outlet pressures that maximize the efficiency of the cycle.



Cycle Efficiency

This Code Edit region contains a procedure that calculates the cycle efficiency as a function of pump output pressures. The procedure calculates


the enthalpies, entropies, specific volumes and temperatures at every point,


the fraction of water removed at the high and low pressure turbine extraction points,


and the work done by the pumps.


The procedure can be modified to return any of these values; right now, it only returns the efficiency.


Procedure to Calculate Efficiency as a Function of Pressures at Points 2 and 4


Hence if both pumps output at 105 Pa, then the cycle efficiency is

eta(10^5, 10^5)



Optimization:-Maximize(('eta')(P2, P4), initialpoint = {P2 = 10^5, P4 = 10^5}, method = nonlinearsimplex, evaluationlimit = 300)

[.471565463928086515, [P2 = HFloat(2122256.300886693), P4 = HFloat(3.3424107988980487e7)]]