Objectives Used Fluent and PCGC-3 to predict the following: Flow profiles Temperature profiles

1. Introduction • At high temperatures CO2 is known to dissociate into CO and O. • A prototype unit using only solar energy has achieved a 4-6 mole percent CO conversion from CO2. • The prototype device was modeled using two different modeling programs (PCGC-3 and Fluent). • Objectives • Used Fluent and PCGC-3 to predict the following: • Flow profiles • Temperature profiles • Reaction kinetics • Reaction mechanisms • Thermodynamic equilibrium • Photolysis reaction Prototype Apparatus Converter in sun 6 m2 solar mirrors Silver solar converter 8 cm zirconia rod • Prototype Description • Mirrors focus sunlight into converter. • Zirconia rod in converter is heated by sunlight to approximately 2350°C. • CO2 stream is passed over hot rod causing CO2 to dissociate into CO and O2. • Product stream (4-6 mole percent CO) is cooled quickly. • CO is separated and used in water-gas shift reaction. Elementary Reactions The following reversible elementary reactions are known to occur in the converter. CO2 + M  CO + O + M CO2 + O  CO + O2 O2 + M  O + O + M CO2 + hν  CO + O(photolysis) Modeling the Direct Solar Conversion of CO2 to CORalph Price, David Morse, Steven Hardy, Thomas FletcherBrigham Young University, Provo, UTScott Hill Reed JensenCombustion Resources, Provo, UT Renewable Energy Corporation, Los Alamos, NM Reaction Kinetics and Equilibrium Parameters were found for the equation: k=A*Tb*exp(-Ea/RT) Reaction rate parameters Equilibrium species fractions Fluent Profiles Predicted temperature Predicted CO mole profile with reactions fraction profile Predicted radially- Predicted velocity averaged temperature profile versus axial distance PCGC-3 Profiles Predicted temperature Predicted CO mole profile with reactions fraction profile Predicted radially- Predicted CO mole averaged temperature fraction from versus axial distance photolysis • Conclusions • Fluent model accurately predicted experimental CO conversion. • PCGC-3 model was accurate in modeling formation of CO, but not cooling. • Residence time and temperatures in the throat were too low to permit significant photolysis. • The formation of CO occurs only in the throat area and not upstream of the rod. • Solar conversion of CO2 to CO has the potential to provide a useable fuel from a CO2 stream. Acknowledgements This work was sponsored by Renewable Energy Corporation Los Alamos, NM ACERC