DECANE CRACKING EQUATION CRACK

This paper rigorously validates the RANS models against the DNS on predicting turbulent flow and heat transfer of highly buoyant horizontal supercritical fluids. Most recently, Wang and Hooman made a comprehensive review on the simulation methods utilised in supercritical fluids and found the LS low-Reynolds number model that works well in some self-developed in-house codes performs poorly in the commercial CFD platforms, such as FLUENT, StarCD and CFX. According to the relevant studies in literature involving model examinations under a wide range of supercritical conditions, the two-layer RNG (Re-Normalization Group), AKN (Abe-Kondoh-Nagano ), LS (Launder-Sharma ) k − ε model, the SST (Shear-Stress Transport ) k− ω model and the four-equation model of k − ε − v 2 − f (Behnia, Parneix and Durbin ) outperform over others, particularly on buoyancy reproduction, which is largely attributed to that the flow and heat transfer behaviours of near-wall fluids are better resolved through these low-Reynolds number models. Turbulence model selection and validation are vital in RANS calculations that guarantees the reliability of the obtained results, this gets more salient for the supercritical computations treating with the significant nonlinearities of physical properties. Thus, the thermal cracking in the connection pipe should be more carefully analyzed in cracking models.

DECANE CRACKING EQUATION CRACK

The results also show that n-decane continues to crack with almost half of the n-decane conversion in the connection pipe. The predicted fuel and wall temperatures are in good agreement with experimental data. The “SST k–ω model” can better predict the wall temperature than other turbulence models. Three turbulence models were tried out and then compared to the experimental results. A computational fluid dynamics (CFD) model was developed using the real thermal properties and coupled with fuel flow, heat transfer, and wall thermal conduction. A global reaction model is given for n-decane conversions less than 13%, including 18 main product species. The results showed that the second-order reactions increase the formation rates of the light products (especially CH4 and C2H4) for conversions greater than 13%, while the heavy product (C5–C9) formation rates are decreased. An electrically heated vertical tube (2 mm inner diameter) was applied to carry out thermal cracking of supercritical pressure n-decane at various pressures, temperatures, and resident times. The flow and heat-transfer behavior of thermal cracking n-decane was investigated experimentally and numerically.

Decane Cracking Equation