Reliable and Carnotized Rankine Cycle Multiple CFWHS P

Reliable and Carnotized Rankine Cycle : Multiple CFWHS…. P M V Subbarao Professor Mechanical Engineering Department A Truly Concurrent Model for PGS ……

Rankine Cycle with Double Closed Feed Water Heaters 1 2 3 12 9 10 11 5 6 7 4 8

Analysis of Regeneration through Two CFWHs Define y as fraction of mass extraction: 1 T 9 7 6 5 2 10 12 11 3 4 8 s

Energy Balance for HP-CFWH

Energy Balance for LP-CFWH

Cost to Benefit Ratio for Rankine Cycle with Two CFWHs Efficiency of cycle

Clues for Optimal Selection of two CFWHs Maximum irriversibile liquid heating to be eliminated = The total enthalpy rise to produce saturate water @pmax. T = hf – h 6 1 f 10 2 9 11 7 6 The enthalpy rise of feed water in the 8 HP-CFWH = h 12 -h 9. 5 s 3 The enthalpy rise of feed water in the HP-CFWH = h 9 -h 6. 12 4

Rankine Cycle with two OFWHs : An Approximation to CFWHs Steam Turbine 1 2 12 3 9 10 11 4 5 7 6 8

Rankine Cycle with two OFWHs : Generalized Notations for Fixed Cordinal Points – Steam Turbine Live Steam, L 2 12 3 9 10 11 7 Dead Steam, D Saturated Water at nearly ambient temperature, A 8 6

Rankine Cycle with two OFWHs : Generalized Notations for Variable Cordinal Points – L First Bleed, b 1 Steam Turbine Second Bleed, b 2 Pumped Feed water, pf 3 D A Pumped Feed water, pf 1 Saturated Feed water, sf 2 Saturated Feed water, sf 1

Rankine Cycle with two OFWHs : Generalized Notations for Variable Cordinal Points – Steam Turbine L First Bleed, b 1 pf 3 Second Bleed, b 2 A pf 2 sf 2 D sf 1 pf 1

Temperature-Entropy Diagram for Rankine Cycle with Two CFWHs L sf 3 T b 1 pf 3 pf 2 pf 1 A sf 2 b 2 Efficiency of cycle sf 1 D 0 S

Important features of Rankine Cycle with OFWH Maximum irriversibile liquid heating to be eliminated = The total enthalpy rise to produce saturate water @pmax. = hsf 3 – h. A The enthalpy rise of feed water in the HP-OFWH = hsf 2 -hpf 2. The enthalpy rise of feed water in the LP-OFWH = hsf 1 -hpf 1. T L sf 3 b 1 pf 3 pf 2 pf 1 A sf 2 b 2 sf 1 D 0 S