**4. Conclusions**

In this study, the main spray parameters and combustion characteristics for diesel, HVO, dodecane, OMEx and OME1 were evaluated in an ambient at High Pressure and High Temperature installation, with controlled oxygen concentration. The parameters studied were liquid and spray tip penetration, ignition delay, flame lift-o ff length, flame length, flame tip penetration and soot production. These were assessed using four high-speed imaging based optical techniques: schlieren, OH\* chemiluminescence and di ffused back illumination. The operating conditions were defined using as baseline the "Spray A" targets recommended by the Engine Combustion Network (ECN). The main conclusions of this study are summarized below.

Results obtained for the dodecane at the baseline condition (900 K 1500 bar and 15% of O2) for ignition delay, liquid length and flame lift-o ff length are consistent with those found in the ECN database, which provides confidence in the reliability of the results of this study:


**Author Contributions:** Conceptualization, J.M.G.-O.; Data curation, A.A.G.-C.; Formal analysis, A.A.G.-C. and A.G.; Methodology, J.V.P. and C.M.; Project administration, J.M.G.-O.; Resources, J.V.P.; Supervision, J.M.G.-O.; Writing–original draft, A.A.G.-C. and A.G.; Writing–review & editing, J.V.P., J.M.G.-O., C.M., A.A.G.-C. and A.G. All authors have read and agree to the published version of the manuscript.

**Funding:** This research has been partly funded by the European Union's Horizon 2020 Programme through the ENERXICO project, gran<sup>t</sup> agreemen<sup>t</sup> n◦ 828947, and from the Mexican Department of Energy, CONACYT-SENER Hidrocarburos gran<sup>t</sup> agreemen<sup>t</sup> n◦ B-S-69926 and by Universitat Politècnica de València through the Programa de Ayudas de Investigación y Desarrollo (PAID-01-18).

**Conflicts of Interest:** The authors declare no conflict of interest.
