Work

Effect of ammonia and natural gas Co-fueling on combustion and greenhouse gas emissions in a marine diesel engine

Year: 2025

Type: article

Abstract: This study experimentally investigates the effects of fuel blending strategies on combustion and emission characteristics in a single-cylinder, four‑stroke marine diesel engine with natural gas and ammonia. Diesel and ammonia were supplied via direct injection, while natural gas was introduced into the intake port through a solenoid-operated valve, forming a premixed charge with intake air. Experiments were conducted at 900 rpm under 50% load, and mixing ratios were systematically varied by adjusting individual fuel injection durations.Four operating conditions were tested—diesel only; diesel & natural gas; diesel & natural gas & NH₃; and diesel & NH₃—reflecting a progressive transition from carbon‑based to low‑ and zero‑carbon fuels. In-cylinder pressure, heat release rate, mass fraction burned, and indicated thermal efficiency were measured, along with emissions of CO₂, NOₓ, and N₂O, to evaluate global warming potential (GWP).Results show that while blending low‑carbon natural gas and carbon‑free ammonia significantly reduces CO₂ emissions, increasing the ammonia ratio diminishes combustion stability and increases N₂O emissions, resulting in a net increase in GWP. These findings indicate that despite ammonia’s promise as a de-carbonization fuel, higher blending levels do not necessarily lead to improved environmental performance.

Source: Case Studies in Thermal Engineering

DOI: 10.1016/j.csite.2025.107344