https://biblio.ugent.be/publication/8589931/file/8609217.pdf

Methanol as a fuel for internal combustion engines

On-board generation of hydrogen-rich gaseous fuels—a review

The use of decomposed methanol, i.e., hydrogen and carbon monoxide, in spark-ignition engines is reviewed. The emphasis is on onboard decomposition and the paper docs not deal with engines fueled by stored hydrogen. The paper concentrates mostly on the experimental work performed using catalytically decomposed methanol, where the methanol is used as a hydrogen carrier. The greatest potential for this type of engine, besides the low energy consumption, lies in the low emissions of nitrogen oxides when running at lean air/fuel ratios. An active and selective catalyst for the decomposition reaction is essential for the utilization of this concept. A literature review on catalyst investigations is included. Neat methanol engines arc not readily started at low ambient temperatures. The possibility of using decomposed methanol as a cold start fuel for methanol engines is reviewed. Decomposed methanol has been proposed as a fuel for gas turbines. A brief review of this subject is also included.

Decomposed Methanol as a Fuel—A review

The current work investigates the flame structure and the propagation of premixed laminar flame fronts for mixtures of diluted methanol–air enriched by fuel reforming products under spark ignition engine conditions. Two engine concepts were investigated: one with external fuel reforming (EFR) and one with reformed exhaust gas recirculation (R-EGR). Here, the fuel reformate (or syngas) is a mixture of H2, CO, and CO2 with a CO selectivity of 6.5%, which is used to represent the products of methanol steam reforming over a Cu–Mn/Al foam catalyst. The simulations were exercised over a wide range of dilution level and unburned gas temperature at 40 bar with a skeletal chemical kinetic mechanism using zero/one-dimensional codes. Two types of dilution—air and EGR—were compared at the same fuel-to-charge equivalence ratio (ϕ′). The results showed that the knock limit for spark-ignited operation is extended with rising dilution levels, especially when diluted by an R-EGR mixture. Syngas addition also leads to a re...

Computational Study of the Laminar Reaction Front Properties of Diluted Methanol–Air Flames Enriched by the Fuel Reforming Product

The feasibility of a proposed exhaust-gas reforming process, as applied to hydrocarbon and alcohol spark-ignition engine fuels, has been studied. In the first instance, a theoretical approach is reported. Complex chemical equilibria and energy balance software has been developed, and used to simulate exhaust-gas reforming reactions for n-heptane and methanol feedstocks. Engine combustion of reformed fuel compositions thus predicted has then been modelled by means of in-house developed cycle analysis software. An important preliminary part of the cycle simulation exercise was the calculation of reformed fuel laminar flame speed, and hence heat-release duration and commencement values. The results of the simulations have enabled comparisons of predicted engine thermal efficiency and pollutant emission levels for reformed and conventional fuelling strategies. Conclusions of the theoretical studies were sufficiently encouraging to warrant a practical investigation, and hence the design, construction and commissioning of a prototype reforming reactor and test rig are described. A test programme was then conducted, in order that the effect of various relevant parameters on reformer performance could be established. The findings of this study were encouraging in terms of the fuel compositions which could be produced, and in the case of an n-heptane feedstock, results were found to correlate well with those of the earlier predictive work. Major limitations highlighted by the practical work, however, relate to high reformer temperature requirements, and low reformed fuel generation rates. The findings of the studies are drawn together in a discussion of the practical feasibility of a vehicle installation, and project conclusions.

Feasibility studies of the exhaust-gas reforming of hydrocarbon and alcohol fuels

Performances et emissions polluantes d'un moteur a allumage par etincelle utilisant comme carburant du methanol dissocie ou reforme a la vapeur

D. M. McCall

Papers

Performance and emissions characteristics of a spark ignition engine fueled with dissociated and steam-reformed methanol