SCO2 Oxy-Combustion Working Group
SCO2 Oxy-Combustion Working Group
Meeting Minutes
July 9, 2019
Presentation
- Dr. Matthias Ihme – Stanford University
- Title: “Thermostructural Analysis and Numerical Modeling for Scalar Mixing and Combustion at Supercritical Conditions”
- Presentation highlights:
- Showed P-T diagram for the Allam cycle
- Two regions of interest
- CO2 pumping/compression
- Mixing and combustion at supercritical conditions
- Part 1 of presentation: molecular structure and thermodynamic properties
- Discussed thermodynamics of transcritical conditions
- Macro-models – EOS and mixing rules
- Can represent fluids as binary mixtures
- Phase behavior depends on mixture constituents
- Mixing Type I
- Type I: Miscible mixing between similar molecules - can be described by common mixing rules
- single critical line in P-T diagram
- Mixing Type III
- More challenging
- Behave as immiscible mixture between dissimilar molecules
- 2 critical lines, 3-phase line on P-T diagram
- Cannot be described by common mixing rules
- H2O/CO2 falls here
- Discussion on their molecular dynamic simulations
- Ar + Kr representative of binary mixture of Type I mixing
- Simulations transition from liquid-like to gas-like regime
- Extract macroscopic properties: Cp vs T at different pressures
- Peng-Robinson EOS does a reasonable job of predicting Type I mixtures
- Ne + Kr representative of Type III mixtures
- In simulations, clusters form – phase separation
- Qualitatively and quantitatively different mixing behavior vs. the Ar + Kr system
- Showed Cp vs T at two pressures
- PR EOS significantly overpredicts heat capacities
- On-going work
- Experimental work to examine phase behavior for sCO2
- Relate scattering signal to thermodynamic response functions for EOS evaluations
- Conclusions
- Type I mixtures are well captured by PR and other EOS
- Type III mixtures are not well captured by PR and other EOS
- Part 2 of presentation: turbulent combustion at supercritical conditions
- Numerical modeling approaches: diffuse-interface method – includes EOS and transport properties
- Challenges exist in modeling real fluids in supercritical state
- Modeling results were shared
- Complex combustion regimes - modeling approaches
- Topology-based approach
- Topology-free approach
- Advantages/disadvantages to each
- How to choose?
- Evaluate performance of combustion models
- Computation cost vs accuracy
- Pareto-front: optimality between two competing conditions - cost and accuracy
- Discussed evaluations of model compliance for different combustion models
- Conclusions
- Developed Pareto efficient combustion (PEC) framework for general description of complex flame configurations
- Includes PEC input parameters and PEC model components
- Application of PEC to a series of flame configurations
- Q&A followed the presentation
Future Meeting
- Next meeting will be in October 2019
- If interested in presenting at a future meeting, contact Seth Lawson