Reactive computational fluid dynamics modelling of methane–hydrogen admixtures in internal combustion engines: Part I – RANS

Abstract

The effects of hydrogen addition to internal combustion engines operated by natural gas/methane has been widely demonstrated experimentally in the literature. Already small hydrogen contents in the fuel show promising benefits with respect to increased engine efficiency, lower CO2 emissions, extended lean operating limits and a higher exhaust gas recirculation tolerance while maintaining the knock resistance of methane. In this article, the influence of hydrogen addition to methane on a spark ignited single cylinder engine is investigated. This article proposes a modelling approach to consider hydrogen addition within three-dimensional reactive computational fluid dynamics in order to establish a framework to gain further insights into the involved processes. Experiments have been performed on a single-cylinder spark-ignition engine situated at a test bed and cater as reference data for validating the proposed reactive computational fluid dynamics modelling approach based around the G-Equation combustion model. Within the course of the first part, crucial aspects relevant to the modelling of the mean engine cycle are highlighted. In this article, a simplified early combustion phase model which considers the transition towards a fully developed turbulent flame following ignition is introduced, along with a second submodel considering combined effects of the walls. The sensitivity of the combustion process towards the modelling approach is presented. The submodels were calibrated for a reference operating point, and a sweep in hydrogen content in the fuel as well as stoichiometric and lean operation has been considered. It is shown that the flame speed coefficient A appearing in the used turbulent flame speed closure, weighting the influence of the turbulent fluctuating speed [Formula: see text], has to be adjusted for different hydrogen contents. The introduced submodels allowed for significant improvement of the in-cylinder pressure and heat release rate evolution throughout all considered operating conditions.

Numerical characterization of hydrogen under-expanded jets with a focus on Internal Combustion Engines applications

“…The Power-to-Gas technology 1 is a feasible solution to store excess of energy by producing hydrogen, which can then be used to power Internal Combustion Engines (ICEs), either pure or blended with conventional fuels. 2 Hydrogen can thus be considered as one of the possible solutions to achieve a climate-neutral mobility along with electric propulsion. 3 Hydrogen shows suitable chemical and physical properties to be exploited in ICEs.…”

A method for determining hydrogen–methane–nitrogen mixtures for laboratory tests of syngas-fuelled internal combustion engines

“…The turbulent flames in spark-ignition engines resemble highly wrinkled laminar flames; 3 hence, the combustion process is governed by the (fast) chemical reaction rates, whereas the turbulent motion can only wrinkle or distort the thin laminar flame zone. 18–21…”

Ensemble-averaged kinematics of harmonically oscillating turbulent premixed flames

“…The work from Yontar predicted the characteristics of a hydrogen/butane dual sequential ignition engine adapting the G-equation as a combustion model [31]. Koch et al analyzed the effects of hydrogen enrichment on the methane internal combustion engine using Reynolds-averaged Navier-Stokes equation (RANS) and large eddy simulation (LES) with Gequation based turbulent flame speed modeling [32,33]. Tuncer et al showed that thermo-acoustic instability-induced flame flashback of hydrogen-enriched methane flames, which contain hydrogen fractions up to 50 %, could be captured using the Gequation, and its results showed good agreement with experiments [34].…”