📋 Case Study
Geothermal Power Plant Working Fluid Selection
Low net power output (<12% thermal efficiency) using isobutane due to poor match with 140°C geofluid
🏗️ Project Overview
Ormat Mammoth Pacific Unit 3 binary cycle upgrade, California
🎯 Challenge
Low net power output (<12% thermal efficiency) using isobutane due to poor match with 140°C geofluid
🔧 Design Approach
Screened 21 organic fluids via PR-EOS thermodynamic screening (η_th, ΔT_pinch, T_crit, GWP); selected R245fa–R134a azeotrope
📐 Design Diagram
AI-generated project design illustration
📐 Key Calculations
Thermal Efficiency (η_th)
(W_turb − W_pump)/Q_evap
Result: 14.8%
Primary economic driver
Pinch Point Temperature
min(ΔT_hot − ΔT_cold)
Result: 4.2°C
Limits heat exchanger size & cost
📊 Results
Efficiency increased to 14.8%, 2.1 MW additional net output, LCOE reduced by 13%💡 Lessons Learned
- •Azeotropic blends improve temperature glide matching but require rigorous EOS mixture rules
- •GWP-weighted fluid ranking must be integrated into early-stage design
✅ Key Takeaways
- 1Azeotropic blends improve temperature glide matching but require rigorous EOS mixture rules
- 2GWP-weighted fluid ranking must be integrated into early-stage design