Optimised Mixture Formation for Diesel Fuel Processing

Abstract

Mixture formation plays an important role in the diesel reforming process. It is important to maintain proper O2/C and H2O/C ratios to avoid hot spots and coking. Fuel must be completely evaporated before entering the reaction zone in order to prevent catalyst damage by coking. Computational fluid dynamics (CFD) is used to optimise the mixing process. Turbulent mixing, diesel spray injections and evaporation and simplified chemical reactions have been calculated. This revealed critical parts of the existing construction. However, experimental verification is necessary. To identify thermodynamic conditions for a possible carbon formation process, experiments with idealised model fuels as well as with real diesel fuel were carried out. Flow visualisation experiments serve for the verification of the CFD simulations. Quartz glass reactors as models of the reformers were operated under real mixing temperatures (400 °C) to observe the effect of the flow profile on fuel sprays. Experiments with coloured fuels were used to visualise the flow and concentration profiles in the mixing chamber. Results were compared with CFD models. Two patented reformers were designed as a result of the CFD optimisation. These were operated for 500 h and 1,000 h respectively with a commercially available diesel, showing very promising results.

Hydrogen-rich gas production by steam reforming of n-dodecane

“…Therefore, liquid fuels such as n-dodecane can be atomized and vaporized into microscopically sized droplets, while the overall reforming efficiency significantly improves by spraying the fuel with injection nozzles [17]. Porš et al [18] and Pasel et al [19] demonstrated that the long-term reforming performance could be improved by spraying the liquid fuel by twin fluid or swirl nozzle. An et al [20] used a twin fluid nozzle to facilitate uniform mixing; they reported that reforming performance increased with shorter distance from the nozzle to the catalytic bed and larger mean drop size of fuel droplets.…”

Planar Solid-Oxide Fuel Cell System Demonstration at UT SimCenter

“…Lenz et al [84] studied autothermal reforming of desulfurized Jet A-l with a 15 kW t test rig and the best energy conversion efficiency of 78.5% was obtained at air to fuel ratio of 0.28 and steam to carbon ratio of 1.5. Pasel et al [85,86] studied autothermal reforming of commercial Jet A-l on a 5 kW e scale. For a C13-C15 alkane mixture surrogate fuel they reported an optimized energy conversion efficiency of 80% at oxygen to carbon molar ratio O2/C = 0.43 and steam to carbon molar ratio S/C = 1.9.…”

“…The high flow velocities and rapid temperature changes could lead to the loss of bonding between the washcoat and monolith walls. Research teams in Argonne National Laboratory [73], Royal Military College of Canada [21,125,126], Forschungszentrum Juelich GmbH in Germany [86,114,127], and KTH-RIT in Sweden [19] have done a significant amount of research of ATR in monolithic reactors. For diesel ATR in monolithic reactor, Shigarov et al [128] tested several catalyst composites and the optimum operating conditions were specified as O2/C ratio of 0.5-0.6, S/C ratio of 1.5-1.7 and inlet mixture temperature of 300-400 °C.…”

An Investigation into the Transient Behavior of a Microreactor System for Reforming of Diesel Fuel in the kW Range

“…However, with the advent of both CHP (combined heat and power) and APU (auxiliary power unit) systems in the 1-10 kW range for both stationary and mobile applications, the load change behavior has become more significant. Many examples can be found in the literature with respect to diesel reforming, be that surrogate diesel reforming using, for example, hexadecane [2], dodecane [3], and tetradecane [4] or more commercial diesel feedstocks [5]. The resulting reformates have found application in many fields, such as for marine use [6], rail use [7], military use [8], and for commercial vehicles [9].…”