Modeling and simulation for n-decane cracking flow based on detailed reaction kinetics and complete real gas thermodynamics under supercritical pressure

Abstract

The real gas thermodynamics and the detailed reaction kinetics are two crucial components in studying the flow of hydrocarbon fuel with cracking reactions under supercritical pressure. However, these two aspects have not been effectively integrated to provide stable and accurate predictions of experimental results. This study combined a detailed cracking mechanism with a real gas thermodynamic model based on the Peng-Robinson equation of state, and introduced real gas chemical potential. By comparing with experimental measurement results, the impacts of the thermodynamic and reaction models on simulation accuracy were carefully studied. The results demonstrate that, within a wide range of conditions (pressure 3–10 MPa, flow rate 1–5 g/s, temperature 300–1004 K), the calculation model based on real gas thermodynamics predicts outlet temperatures and conversion rates with higher accuracy compared to ideal gas. The non-ideal gas effect of chemical potential at 3 MPa has a slight impact on the n-decane cracking reaction system. But this effect increases with increasing pressure. Under 10 MPa pressure, the real gas effects of chemical potential may result in changes reaching 40% in the rate of progress variables (ROPs). Furthermore, when using the same complete real gas thermodynamics, the Detailed mechanism has higher accuracy in predicting fuel temperature, conversion rate and product distribution, than PPD or Lumped mechanisms. The differences in the simulation results from different reaction models mainly due to the different descriptions of reaction rate rules and intermediate products. This work provides a more accurate method for simulating the supercritical pressure cracking process of fuel in cooling channels.