Fig. 2: Theory constrained by emission and contrail observations can explain contrail ice formation on volatile particles under low-soot, lean-burn combustor conditions.
From: Substantial aircraft contrail formation at low soot emission levels
Dependence of contrail ice crystal numbers on combustion mode and fuel composition. The symbols show mean and arithmetic standard deviation of non-volatile (EInv, d > 14 nm) and ice (EIice, d > 0.6 µm) particle number emissions indices measured under lean-burn and forced rich-burn combustor configurations for Jet A-1 (black) and a HEFA-blend (green) at 218 K ambient temperature. The lines denote simulations with the updated ACM model3 at comparable conditions (218 K, 10 K below TSA; refs. 39,50) for lean- and rich-burn combustion modes and three fuel composition cases (Jet A-1 with 192 ppmm sulfur; HEFA-blend with 75 ppmm sulfur; and HEFA-SPK with 3 ppmm sulfur; see also Table 1). The grey dotted line indicates the 1:1 relationship. More details on measurement conditions for the near-field emission and the far-field contrail measurements are provided in the Methods and Extended Data Tables 2 and 3. Reduced ice particle number emission indices were measured and modelled for low-sulfur low-aromatic HEFA-blend compared with Jet A-1.
