Power Generation Using Multi Component Working Fluids. P M V Subbarao Professor Mechanical Engineering Department Indian Institute of Technology Delhi. Synthesis of More Appropriate Working Fluids……. A. Flue gases. External Irreversibility-1. 1. 1. C. 6. 1kg . 8. Steam. 5. 7. T.
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P M V Subbarao
Mechanical Engineering Department
Indian Institute of Technology Delhi
Synthesis of More Appropriate Working Fluids……
External Irreversibilities with Rankine cycleIrreversible Heat transfer process : Rankine Cycle
Low pressure and low temperature region
Fig 2 Layout of modern Coal fired power plant
Exit at higher velocity
Kinetic Energy loss
12.65 m3/ kg
Location of condensation process in a Low pressure steam turbine
(Source Alstom )
For example, a long, full speed rotor blade, operating in a non-reheat cycle, may involve wetness levels of about 15% at
Without suitable counter-measures this can result in extreme tip-erosion (illustrated in Fig).
Erosion of a long last stage blade
( Source Alstom )
In principle, a divergence in the thermal behaviour between a working fluid and a source or sink can be counteracted by using complex cycle configurations such as evaporation at multiple pressure levels in modern combined cycles or condensation at 2 or 3 decreasing temperatures in cogenerative systems.
The pump pressurized the saturated liquid (5) which is leaving from the condenser and it is sent in to the high temperature recuperator (6).
The liquid takes off the heat from the two phase dead vapour (3).
The pressurized hot liquid (sub-cooled state) enters (1) into the vaporizer where the liquid is converted in to vapor (2) by utilizing the latent or sensible heat of the hot source (1s-2s).
The saturated vapor (2) from the vaporizer is expanded in the turbine up to its condenser pressure.
The two phase mixture after giving a part of it’s latent heat to the incoming liquid (4) enters in to the condenser, where cooling water enters (1w), takes away all the heat available in the two-phase mixture, and leaves at higher temperature (2w).
The saturated liquid is pressurized in the pump and the cycle repeats.
The heat transfer rate QV(W) between the source and the working fluid is calculated by
optimization methodology ‘Monte Carlo’.
First law efficiency of the cycle is defined as
Variation of first law efficiency at different steam inlet conditions of simple
Saturation Pressure of Rankine Cycle (bar)
Effect of variation in fraction of ammonia at the evaporator inlet on first law efficiency
Condenser pressure in the Ammonia water cycle largely depends on cooling water inlet temperature and fraction of Ammonia in the Ammonia water mixture.
For the same cooling water inlet temperature, decreasing the Ammonia mass fraction at the condenser inlet will reduce the condenser pressure and it will leads to larger expansion process in the turbine and hence more power output and higher efficiency
The following modifications are suggested for the proposed Ammonia water cycle when compared to KCS 34.
1.Super heater is added in the cycle to utilize the superheated steam at low temperature and pressure.
The saturated vapor from the separator is superheated in the super heater before entering the steam turbine.
2.The additional feed water is included in the system, which utilize the sensible heat of low grade to heat the sub-cooled water coming it from the condenser of an Ammonia water cycle