A comparison of Alternative Fuels Spray Characteristics from a Marine Pump-Line Nozzle Injector
Year: 2026
Type: conference-paper
Abstract: The maritime sector faces an urgent need to reduce greenhouse gas emissions as largescale electrification remains impractical for ocean-going vessels due to energy density, range, and infrastructure constraints. Therefore, low-carbon liquid fuels compatible with existing diesel technology are considered a pathway for near- and mid-term defossilization. However, these alternatives often exhibit physical properties that differ from conventional diesel, potentially affecting fuel injection and spray formation processes. Fuel spray formation is governed by a complex interaction between injector geometry, injection dynamics, and fuel properties such as density, viscosity, surface tension, and bulk modulus. While the influence of these properties has been studied extensively for automotive-scale common-rail diesel injectors operating under quasi-steady injection pressures, comparatively little experimental data is available for large pump-line-nozzle (PLN) injectors typical of marine engines, where injection pressures are highly unsteady and cavitation behavior may differ significantly. High-speed shadowgraph imaging experiments were conducted in a 4.1 L constant-volume combustion chamber to investigate the spray behavior of evaporating sprays issued from a marine PLN injector. Four fuels are compared: conventional diesel, hydrotreated vegetable oil (HVO), Jet A1 fuel, and methanol, at two ambient conditions. In addition to visualization of the vapor phase, the needle lift and injection pressure are measured to account for differences in injection dynamics between fuels. Clear differences between fuels are observed in the PLN system, while those are generally minor for common rail systems. Lower compressibility fuels result in advanced injection timings and higher injection pressures. This results in increased injection velocities and a faster vapor phase penetration. The low L/D ratio of the nozzle however results in a strong and transient cavitation behavior. At higher ambient pressure, a strong difference in spray angle is observed between the fuels, but no clear link between fuel properties and spray angle could be found. Methanol’s high compressibility causes low injection pressures, resulting in a lower momentum flow rate and slower vapor phase penetration. Additionally, methanol’s low viscosity causes leakage flows at the injector nozzle.
Institutions: Ghent University, Universitat Politècnica de València
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7224724653