Investigation of the spray formation of solketal under diesel engine conditions and the influence on Diesel R33

The defossilization of diesel fuels presents a multitude of new opportunities and challenges. Due to the increase in complexity and interactions between the components, it is necessary to examine the drop-in capability of new fuel components. One aspect of this is the influence on spray formation of the fuel. This work addresses the spray behavior of isopropylideneglycerine (solketal) and its influence on a multicomponent diesel blend (Diesel R33: 33 % renewable share). In general, it represents the first spray study of solketal. It enables value to be added from glycerin and, according to initial combustion tests, has a promising emissions profile due to its higher molecular oxygen density. The mass flow rate, penetration depth and cone angle were examined by using high-temperature and -pressure injection chamber equipped by optical diagnostics (Mie scattering setup and schlieren imaging system). These parameters are examined under varying fuel temperatures, injection pressures and ambient conditions. Solketal as a pure compound exhibits the expected behavior i.e. it is drop-in compatible even with varying parameters. The influence of solketal on Diesel R33 reveals that, in comparison to solketal-free blends, larger maximum mass flows are generated. It also shows that the penetration depths decrease (up to 34 %). In addition, there is more fuel in the gas phase, which may be a result of the comparatively low boiling point. In general, the influence of solketal suggests that fuel-induced soot reduction could be possible in existing fleets.