**4. Conclusions**

The present work has investigated the effectiveness of different strategies to maximize the efficiency of RCCI combustion in a single-cylinder heavy-duty diesel engine. The solutions explored consisted of the optimization of the engine settings, modification of the piston bowl geometry, and variation of the low reactivity fuel properties. The major findings from this study are summarized as follows:


**Acknowledgments:** The authors acknowledge VOLVO Group Trucks Technology for supporting this research and express their gratitude to the Spanish economy and competitiveness ministry for partially funding this investigation under the project HiReCo (TRA2014-58870-R). The author J. Monsalve-Serrano thanks the Universitat Politècnica de València for his predoctoral contract (FPI-S2-2015-1531), which is included within the framework of Programa de Apoyo para la Investigación y Desarrollo (PAID).

**Author Contributions:** J.B. and A.G. conceived and designed the experiments; J.M.-S. performed the experiments; J.M.-S. and V.B. analyzed the data and wrote the paper. All authors discussed the results and commented on the manuscript at all stages.

**Conflicts of Interest:** The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
