Enhancing Low Temperature Lean Combustion of CH4-H2 Blends through a Prechamber Equipped Engine Università degli Studi di Firenze

Format:

Book

Conference/Event

Author/Creator:

Balduzzi, Francesco, author.

Contributor:

Di Iorio, Silvana

Ferrara, Giovanni

Sementa, Paolo

Conference Name:

2024 Small Powertrains and Energy Systems Technology Conference (2024-11-04 : Bangkok, Thailand)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2025

Summary:

The use of hydrogen as a sustainable fuel in the short term is hampered by the impossibility of large scale use due low availability. In order to promote decarbonization, complementary solution for a smooth transition is to dilute it in a mixture with methane, in a current Port Fuel Injection (PFI) internal combustion engine (ICE). This can be done as a retrofit after limited structural modifications, such as the introduction of a passive prechamber. Such a solution allows a reduction of the carbon footprint of traditional ICEs through more efficient combustion (both the prechamber technology and the hydrogen fuel properties promote an increase in combustion speed) and a reduced carbon content in the fuel.The present research activity has been carried out through numerical investigation based on three-dimensional CFD analyses to simulate the behavior of a natural gas engine fueled with CH4-H2 blends. The combustion mechanism for the fuel blend was validated against measurements of the flame front propagation carried out on an optical engine.The focus of the work is to evaluate the effect of both the hydrogen share and the charge dilution. The introduction of a passive prechamber was necessary to stabilize the mixture ignition and increase the combustion speed. In particular, simulations were carried out for increasing hydrogen content, from 0% to 30% in volume, and increasing excess air from stoichiometric (λ=1.0) to ultra-lean (λ=1.8), in order to achieve a Low Temperature Combustion (LTC). For each operating condition investigated, the ignition advance was optimized in order to maximize the gross indicated mean pressure (GMEP). The results show that, at λ = 1.4, 20% H2 is sufficient to obtain a slightly higher GMEP than using pure CH4, while at the same time guaranteeing a 40% reduction of raw NOx emissions. When further increasing the value of λ up to 1.8, slow combustion is obtained even with 30% share of H2. In this case, hot EGR is needed to increase the reactivity of the mixture and allow achieving a complete combustion

Notes:

Vendor supplied data

Publisher Number:

2024-32-0044

Access Restriction:

Restricted for use by site license