Mechanical Engineering - Energy Systems LM

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ES 2025-2026: Individual Focus Report (7CFU) Topic 17 - Steam Power Plant heat power rejection Fabio Santoro - xxxxxxxx December 22, 2025 Steam Power Plant heat power rejection Introduction Steam power plant Energy Flow Sankey Diagramη boiler≈90% ηnet≈40%approximately 45% of fuel power is rejected by the plant through thecondenserES: IFR2 100 fuel input 102 2 FW pump 40 Net Power output 3 auxiliaries 2 thermal losses 45 heat rejected by condenser 10 flue gases at stack s T T cond 4 1 2 Q cond Steam Power Plant heat power rejection Introduction and classification Refrigerantliquid (water)gas (air)open loop closed loop air coolerriver, lake & sea wet cooling tower dry cooling tower Focus on: •Open loop water •Wet cooling tower •Air coolerES: IFR3 ST condenser FW pump 3 4 1 2 ~ Ref out Ref in Q cond Steam Power Plant heat power rejection Introduction - Generic temperature profiles ∆T cs≃20−25◦ C ∆Tcs= ∆T ref+ ∆T hs How to choose ∆Tref? ˙mref=˙ Qcondc p,ref·∆T ref⇒˙m ref∝1∆T ref Acond=˙ QcondU·LMTD LMTD≜∆T cs−∆T hsln  ∆Tcs∆T hs if ∆Ths→0⇒A cond→ ∞ES: IFR4 T Q 1 SL (1 sc ) Ref in Ref out A con d = ∞ 4 ΔT cs ΔT ref ΔT hs T amb T cond Q cond Steam Power Plant heat power rejection Introduction - CAPEX vs OPEX ˙m ref⇔OPEX: operative costs Acond⇔CAPEX: investments costs Optimum ∆Tref,optthat minimize costs Analysis for the three systems: •Brief description •Temperature profiles •Operational issues •Constraints •Economic considerations •Layout ConsiderationsES: IFR5 cost ΔT cs ΔT ref OPEX CAPEX ΔT ref,opt opt CAPEX+ OPEX Steam Power Plant heat power rejection Air-cooler description Extended surfaceHeat Exchanger for the air side with Fins: low air convective coefficienthairConfront water (w) vs air (a) ˙ma˙m w= cp,wc p,a |{z} ∼4·  ∆Tw∆T a |{z} ∼1≃4 ˙ Va˙ Vw= ˙m a˙m w |{z} ∼4·  vav w |{z} ≫1≃3200 AaA w= U wU a |{z} ≫1·  LMTDwLMTD a |{z} ∼1≫1 ES: IFR6 1: condensate liquid headers 4: steam header Fins on air side Q cond Q cond fan air Steam Power Plant heat power rejection Water-cooled Open Loop configuration Environmental Restrictions rules on: •˙mref •∆Tref Refigerant pool: •small: river •big: lake/sea/ocean Shell&Tube Heat Exchanger (HE) Small but efficient Power plant∆T river= ∆T ref ˙mref˙m river |{z} ≪1 ∆Triver≤2-3◦ CIso-Thermal lines Corrosion problemES: IFR7 power plant Ref in Ref out River Q cond power plant Ref in Ref out Q cond Lake/Sea/Ocean Iso-T Steam Power Plant heat power rejection Water-cooled Closed Loop configuration - Wet cooling tower ˙m eva˙m drift˙m eva˙ Qeva= ˙m eva∆h eva˙m make-up˙m blow-down˙m make-up= ˙m eva+ ˙m drift+ ˙m blow-down≃3-5% ˙m refHeat/Mass transferForcedvsNaturaldrift PowerDriftHeight [GW][m] ∼0.5 Natural 40-70 ∼1 Natural 100-160 ≤0.1 Forced 5-20 Dry Air⇒Wet Air Expensive structure Direct Contact HE Small refrigerant pool Ta