Particle emissions from a modern heavy-duty diesel engine as ice nuclei in immersion freezing mode: a laboratory study on fossil and renewable fuels

Abstract

Abstract. We studied ice-nucleating abilities of particulate emissions from a modern heavy-duty diesel engine using three different types of fuel. The polydisperse particle emissions were sampled during engine operation and introduced to a continuous-flow diffusion chamber (CFDC) instrument at a constant relative humidity RHwater=110 %, while the temperature was ramped between −43 and −32 ∘C (T scan). The tested fuels were EN 590 compliant low-sulfur fossil diesel, hydrotreated vegetable oil (HVO), and rapeseed methyl ester (RME); all were tested without blending. Sampling was carried out at different stages in the engine exhaust aftertreatment system, with and without simulated atmospheric processing using an oxidation flow reactor. In addition to ice nucleation experiments, we used supportive instrumentation to characterize the emitted particles for their physicochemical properties and presented six parameters. We found that the studied emissions contained no significant concentrations of ice-nucleating particles likely to be of atmospheric relevance. The substitution of fossil diesel with renewable fuels, using different emission aftertreatment systems such as a diesel oxidation catalyst, and photochemical aging of total exhaust had only minor effect on their ice-nucleating abilities.

Marine Fuel Regulations and Engine Emissions: Impacts on Physicochemical Properties, Cloud Activity and Emission Factors

“…At 50 nm, κ is reduced to 0.035–0.079. These hygroscopicities agree with measurements from other diesel engine studies of unaged soot particles (Henning et al., 2012; Korhonen et al., 2022; Wittbom et al., 2014). The strong reduction in hygroscopicity compared to HiS was observed for all measured particle sizes as κ continues to decrease monotonically with increasing particle size.…”

Time dependence of heterogeneous ice nucleation by ambient aerosols: laboratory observations and a formulation for models

“…It is less clear to what extent combustion emissions may play a role as INPs in mixed-phase clouds. Fresh and photochemically aged pollution from "modern" car engine emissions does not appear to contain significant concentrations of immersion freezing INPs (Chou et al, 2013;Schill et al, 2016;Korhonen et al, 2022). On the other hand, ships may emit INPs (Thomson et al, 2018).…”