Advanced Modeling of Thermodynamic Energy Components and Systems

Volume 1 – From Foundation to Professional Engineering

🎯 Bridging Theory and Industrial Reality

This volume marks a critical transition in the learning journey: from understanding what energy systems do (covered in the 2021 edition) to mastering how they actually behave in real-world conditions.

The Gap in Traditional Education

Even after mastering basic thermodynamic cycles, students and young engineers often face a disconnect:

❌ Textbook models use idealized assumptions (perfect gases, 100% efficiency, design-point only)
❌ Real components have technological constraints (material limits, surge margins, fouling)
❌ Industrial systems operate off-design most of the time (part-load, varying ambient conditions)
❌ Component interactions in complete systems create behaviors not predictable from isolated analysis

Result: Graduates struggle to transition from academic knowledge to professional engineering practice.

Our Solution: Technologically Realistic Modeling

This volume provides the analytical tools that professional engineers actually use:

✅ Realistic component models – Performance maps, efficiency curves, technological limits
✅ Off-design analysis – Behavior under actual operating conditions
✅ Systemic integration – Understanding component interactions in complete cycles
✅ Advanced methods – Exergy structures, functional analysis, external class development
✅ Professional software skills – Thermoptim external classes and custom controllers

📚 Building on the 2021 Foundation

What the 2021 Edition Provided

The foundational book established:

• Basic thermodynamic cycle understanding
• Visual modeling with Thermoptim (simplified approach)
• Introductory component functions
• Qualitative system analysis (CFRP method)
• Modes 1-2 pedagogy (accessible to all levels)

What Volume 1 Adds

This volume elevates the approach to professional standards:

📖 Content Structure: Three Integrated Parts

Part I: Methodological Foundations (Chapters 1-5)

Chapter 1: Presentation of the Approach

A Two-Level Methodology for Energy Systems

This chapter presents a revolutionary two-level methodology for analyzing energy systems, based on the observation that thermodynamics is simpler in qualitative than quantitative terms.

Key Concepts:

• Energy technologies as component assemblies: Using a gas turbine as introductory example, demonstrates how fluids flow through components and undergo thermodynamic processes
• Dual analytical-systems approach: Separates the challenge of complex fluid behavior laws from component coupling
• Functional structure: Describes physical organization and processes
• Exergy structure: Evaluates energy quality through exergy flows, conversions, and losses

Thermoptim Implementation:

• Diagram editor for qualitative system description
• Simulator for quantitative analysis
• Primitive types basis: Substances, points, processes (compression, expansion, combustion, throttling, heat exchange), nodes (mixing, division, separation), and heat exchangers
• Three component model categories:
  • Phenomenological models for thermodynamic cycle studies
  • Empirical behavior models for off-design operation
  • Technological design models for detailed internal component analysis

External Class Mechanism: Extends the core primitive types through Java classes for specialized components, enabling focus on innovative cycle development essential for future energy challenges including CO₂-free emissions.

Chapter 2: Thermodynamics Fundamentals

Simplified, Practical, and Applied Foundations

This chapter presents the fundamental thermodynamics knowledge required to study energy technologies, with emphasis on simplicity and practical application.

Core Topics:

• Basic concepts: Open and closed systems, state variables, reversible processes
• Energy exchanges: Work, heat transfer, and their expression in thermodynamic processes
• First and Second Laws: Comprehensive review providing theoretical foundation for calculations
• Exergy: Accounting for both energy quantity and quality

Substance Properties:

• Cascade of nested models: Perfect gases → ideal gases → real condensable fluids
• Practical applications: Moist mixtures, refrigerant blends, real fluid mixtures
• Thermodynamic diagrams: Clapeyron, entropy, Mollier, enthalpy-pressure, and exergy diagrams to visualize fluid properties and cycle representations

Philosophy: Makes applied thermodynamics accessible while maintaining rigor for energy technology calculations.

Chapter 3: Basic Components and Processes

Physical Phenomena and Calculation Methodology

This chapter examines the physical phenomena governing main component types in energy conversion technologies and their calculation in Thermoptim.

Components Covered:

• Compressions: Displacement and dynamic compressors
• Expansions: Turbines
• Combustion: Complete and incomplete reactions, pollutant formation mechanisms
• Throttling operations
• Moist mixture treatments: Air conditioning processes (heating, cooling, humidification, dehumidification)

Performance Characterization:

• Irreversibilities and efficiency definitions (isentropic and polytropic)
• Off-design behavior
• Dimensionless parameters and performance maps
• Energy balance calculations

Outcome: Engineers gain tools for accurate energy technology modeling with practical examples and Thermoptim calculation procedures.

Chapter 4: Heat Exchangers

Principles and Calculation Methods

This chapter presents comprehensive treatment of heat exchangers, devices that transfer heat between fluids at different temperatures.

Fundamental Methods:

• LMTD (Log Mean Temperature Difference) method
• Overall heat transfer coefficient U: Effects of fins and convection correlations
• NTU (Number of Transfer Units) method (Kays & London): Relates exchanger effectiveness to design parameters

Configurations Analyzed:

• Counter-flow, parallel-flow, cross-flow (mixed and unmixed)
• Shell-and-tube exchangers
• Matrix formulation for complex heat exchanger networks
• Series and series-parallel assemblies

Key Concepts:

• Pinch point as critical design constraint
• Thermoptim implementation: “Exchange” processes, thermocouplers, design procedures

Bridge: From theoretical foundations to engineering practice, providing tools for preliminary system analysis and detailed thermal design.

Chapter 5: External Class Development

Extending Thermoptim Capabilities

This chapter demonstrates how external classes enable Thermoptim to address modeling problems beyond core capabilities through custom Java code.

Three Main Purposes:

1. Custom substances: Simple fluids (Dowtherm A) and complex mixtures (LiBr-H₂O)
2. Specialized components: Flat plate solar collectors, cooling towers
3. External controllers: Optimization and off-design calculations

Detailed Examples:

• External substances: Thermodynamic property servers integration
• Solar collectors: Effectiveness-based models
• Cooling towers: Direct contact with coupled heat and mass transfer
• Moist mixture calculations: External nodes synchronized through mixer-divider combinations

Development Tools:

• Graphical user interface design
• Parameter saving/loading
• Integration with Thermoptim’s calculation engine
• Open-source distribution principles

Impact: Significantly expands Thermoptim’s applicability while maintaining consistency with core thermodynamic framework.

Part II: Component Sizing and Off-Design Behavior (Chapters 6-9)

Chapter 6: Component Sizing and Off-Design Operation

From Phenomenological to Technological Models

Through a concrete example (simple refrigeration cycle), this chapter presents comprehensive treatment of component sizing and off-design simulation.

Two Model Levels Distinguished:

• Phenomenological models: Enable thermodynamic cycle calculations independent of technology choices
• Component sizing/off-design models: Allow geometric dimensioning and performance evaluation under off-design conditions

Fundamental Challenges:

• Off-design analysis is considerably more complex than pure thermodynamic cycle studies
• Component sizing requires refining internal representations to calculate properties from technological parameters
• Strong coupling between components necessitates external controllers
• System adaptation to boundary conditions

Methods Presented:

• Heat exchangers: NTU method for design and off-design performance through matrix formulations
• Displacement compressors: Characterized by swept volume and efficiency laws as functions of compression ratio and rotation speed
• Refrigeration cycle example: How evaporation/condensation temperatures are determined by coupled thermal balances, compressor performance, and heat transfer coefficients varying with operating conditions

Chapter 7: Sizing and Off-Design Behavior of Heat Exchangers

Beyond Simple Calculations

Complementing Chapter 4’s foundation, this chapter explains how to model and configure heat exchangers for sizing and off-design calculations.

Core Challenge: While NTU method provides UA product, sizing requires separate evaluation of:

• Overall exchange coefficient (U): Heat transfer coefficient calculation
• Surface area (A): Geometric configuration selection

Pressure Drop Calculations:

• Single-phase flows (friction coefficients and correlations)
• Two-phase flows

Heat Transfer Modeling:

• Extended surfaces
• Reynolds and Prandtl number calculations
• Nusselt number correlations for diverse configurations:
  • Inside tubes, perpendicular flows, finned coils, plate heat exchangers
• Two-phase exchange: Condensation and evaporation correlations

Special Topics:

• Nucleate boiling in steam generators: TechnoSteamGenerator class implementing ONB detection, FDB identification, pressure drop calculations
• Multi-zone exchanger equations: Evaporators, condensers, combined systems

Geometric Parameter Estimation:

• Direct calculation using geometric data (hydraulic diameter, flow areas, plate exchangers, shell-and-tube)
• Identification from experimental data

Chapter 8: Modeling and Setting of Displacement Compressors

Off-Design Modeling

This chapter focuses on representing displacement compressor behavior through two key parameters:

• Volumetric efficiency (λ): Characterizes actual swept volume
• Isentropic efficiency (ηs): Classical efficiency measure

Loss Mechanisms Analyzed:

• Dead space effects
• Pressure drops in manifolds and valves
• Wall thermal effects
• Leakage losses

Efficiency Laws:

• Volumetric efficiency: Variation with compression ratio and rotation speed, optimum at relatively high speeds
• Isentropic efficiency: Two alternative formulations:
  • Five-parameter model
  • Simpler three-parameter model with clear physical interpretation (limiting efficiency, maximum efficiency, optimal compression ratio)

Practical Implementation:

• Thermoptim technological design screens
• Both adiabatic and cooled compressors
• Fixed internal volume ratio (Vi) rotary positive displacement compressors
• Under-compression/over-compression when operating pressure ratio differs from constructive ratio

Challenges: Parameter identification from scarce experimental data, calculation procedures for design and off-design modes.

Chapter 9: Modeling and Setting of Dynamic Compressors and Turbines

Off-Design Behavior of Turbomachinery

This chapter presents models for turbines, dynamic compressors, pumps, and fans, addressing significant challenges from limited consensus in scientific literature and engineering practice.

Two Main Methodologies:

1. Velocity triangle deformation under changing operating conditions
2. Similarity laws with experimental performance maps

Supplementary Fundamentals:

• Velocity triangle analysis: Leading to Rateau coefficients (power factor μ, flow coefficient δ)
• Degree of reaction relationships
• Theoretical characteristics: Centrifugal compressors, axial compressors, turbines
• Real characteristics: Qualitative analysis of friction and shock losses

Similarity Factors:

• Flow factor (ϕ), enthalpy factor (ψ)
• Specific diameter (Δ), specific speed (σ)
• Enable reduced performance map construction and off-design analysis

Component-Specific Modeling:

• Pumps and fans: Incompressible fluid assumptions simplify modeling; single reduced curves sufficient
• Dynamic compressors: Performance maps using corrected rotation speed and corrected flow; various coordinate systems ((ϕ, ψ), (θ, Δ), (σ, Δ)) for curve consolidation
• Turbines: Stodola’s cone rule, Baumann’s efficiency degradation rule for wet steam, leaving loss calculations based on velocity triangles

Implementation: Practical Thermoptim technological design screens demonstrated for each machine type.

Part III: Case Studies (Chapter 10)

Chapter 10: Case Studies

From Theory to Practice – Progressive Complexity

Four case studies with increasing difficulty demonstrate methodologies for users developing their own models.

Case Study 1: Air Piston Compressor

• System: Compressor with exchanger cooling charging compressed air storage
• Focus: Controller creation, simple off-design analysis
• Tools: Tube-and-fin heat exchanger with Wang-Chi-Chang correlation

Case Study 2: Refrigeration Machine

• System: Displacement compressor, thermostatic valve, two two-phase heat exchangers
• Challenge: Pressures vary with external conditions
• Solution: minPack for nonlinear equation systems (6 coupled equations)
• Algorithms: Nested algorithms for constant UA and adjustable U

Case Study 3: Simplified Steam Power Plant

• System: Turbine and two heat exchangers
• Analysis: Performance evolution when varying cooling water temperature, maximum pressure, or superheat temperature
• Methods: Stodola’s rule, multi-zone exchanger calculations
• Solution: minPack for coupled equations

Case Study 4: Flamanville 3 EPR Turbine

• Unique approach: Data analysis on partial load operation using detailed official data from EDF to French Nuclear Safety Authority
• Load range: 30-100%
• Analysis reveals:
  • Optimal Stodola law formulations
  • Polytropic efficiency variations
  • Separator performance across load range

Major Outcome: Development of NUSCLE software – a simplified model of the thermodynamic cycle of water-cooled nuclear power plants (WCR type: PWRs, BWRs, RBMKs, CANDUs)

Methodology Demonstrated:

• External controllers (both generic and specific versions)
• Real-world data integration
• Progressive complexity in modeling approach

🔧 Advanced Thermoptim Techniques

External Classes

Purpose: Extend Thermoptim beyond built-in capabilities

Applications:

• Custom component models with proprietary correlations
• Integration of performance map data
• Specialized property calculations (thermodynamic property servers)
• Automated optimization routines

Development:

• Java programming interface
• Class structure and templates
• Graphical user interface design
• Debugging and validation
• Distribution and sharing (open-source principles)

Custom Controllers

Use Cases:

• Complex control logic
• Sequential process steps
• Iterative calculations (nonlinear equation systems)
• Multi-variable optimization
• Off-design simulation with strong component coupling

Implementation:

• Controller architecture
• Variable passing and state management
• Integration with Thermoptim projects
• User interface considerations

System-Level Integration

Advanced Modeling:

• Multi-cycle systems (combined cycles)
• Process integration
• Cogeneration networks
• Plant-wide optimization

Data Management:

• Import/export capabilities
• Interfacing with Excel and databases
• Results post-processing
• Reporting automation

📊 Professional Methods and Tools

Exergy Analysis

Beyond energy balances:

• Energy quality: Not all joules are equal
• Irreversibility identification: Where efficiency is lost
• Component evaluation: Relative importance ranking
• Optimization guidance: Where improvements yield most benefit

Exergy Balance Framework:

• Fuel and product exergy
• Exergy destruction in each component
• Exergetic efficiency definitions
• System-level exergy flow diagrams

Functional Structure Analysis

Component-Oriented Methodology:

• Physical organization description
• Process identification and characterization
• Component interconnections
• System architecture understanding

NTU Method for Heat Exchangers

Effectiveness-Based Design:

• Number of Transfer Units calculation
• Performance characterization
• Off-design behavior prediction
• Matrix formulation for complex networks

🎓 Learning Approach

Prerequisites

Essential foundation (from 2021 edition or equivalent):

• Basic thermodynamic cycles (Rankine, Brayton, refrigeration)
• First and second law applications
• Thermoptim fundamental operations
• Energy balance calculations

Recommended preparation:

• Familiarity with Modes 1-2 from 2021 edition
• Basic programming concepts (for external classes)
• Industrial system awareness

Pedagogical Philosophy

This volume assumes Mode 3 (In-Depth) readiness:

• Comfort with mathematical formalism
• Motivation for technical depth
• Professional or research orientation
• Self-directed learning capability

However, the progression remains structured:

• Part I (Chapters 1-5): Establishes methodology and fundamental tools
• Part II (Chapters 6-9): Builds component expertise for sizing and off-design
• Part III (Chapter 10): Integrates knowledge through real-world case studies

Practical Exercises

Throughout the book:

• Worked examples: Step-by-step solutions
• Thermoptim-based investigations: Hands-on modeling
• Parameter studies: Sensitivity analyses
• Case studies: Real plant data (including official EPR data)
• Controller development: Custom Java implementations

🔗 Role in the Complete Series

The Three-Volume Journey

📘 Energy Systems (2021) – Foundation

• What: Introduction to all energy technologies
• How: Simplified, visual approach (Modes 1-2)
• Who: Beginners to intermediate learners

↓ Provides conceptual foundation and basic modeling skills

📗 Volume 1 (THIS BOOK) – Professional Tools

• What: Realistic component modeling, off-design analysis, external class development
• How: Technical, advanced methods (Mode 3)
• Who: Graduate students, engineers, researchers

↓ Develops professional analytical capabilities

📕 Volume 2 (2026) – Specialized Application

• What: Complete nuclear plant cycle analysis
• How: Expert application of all tools (Mode 3 applied)
• Who: Nuclear energy professionals and specialists

Recommended Path

1. Master the 2021 edition (or equivalent foundation)
2. Study Volume 1 for component and systems expertise
3. Apply to specific domain:
   • General energy systems → Use Volume 1 tools directly
   • Nuclear applications → Continue to Volume 2
   • Other specializations → Transfer Volume 1 methods

👥 Target Audience

💡 What Makes This Volume Unique

📥 Getting Started

Essential Resources

• Thermoptim Software – Free demo with full Volume 1 capabilities
• External Class Development Kit – Templates and documentation
• Component Model Library – Pre-built advanced models
• Case Study Database – Real plant performance data

Learning Path

1. Review 2021 foundation – Ensure solid basics
2. Part I (Chapters 1-5) – Master systemic methodology and tools
3. Part II (Chapters 6-9) – Develop sizing and off-design skills
4. Part III (Chapter 10) – Apply through progressive case studies
5. Project work – Apply to real or research system

Support

• Technical documentation – Comprehensive guides
• Example files – All book models available
• Community forum – Peer support and sharing
• Email support – info@thermoptim.org

🚀 Beyond This Volume

Immediate applications:

• Industrial performance analysis
• Research project modeling (sizing and off-design)
• Consulting studies
• Advanced curriculum development

Next steps:

• Volume 2 for nuclear specialization (applying NUSCLE and other tools)
• Professional conferences and networking
• Published research using these methods
• Industrial collaboration opportunities

© Renaud Gicquel, 2026
Contact: info@thermoptim.org