Hydrogenated terpenic renewable fuels: Emissions and combustion analysis

Waste terpenes from paper industry, pine resin tapping or citric industry are abundant feedstocks that can be used as components in diesel blends. However, terpenes such as turpentine or orange oil are highly reactive, tend to form deposits and show high sooting tendency. These drawbacks can be solved with hydrogenation, which reduces the degree of unsaturation of the molecule and thus, the formation of soot. In this work, blends at 20 vol % of hydrogenated turpentine and hydrogenated orange oil in diesel fuel were tested in a Euro 6 diesel engine following Worldwide harmonized Light-duty Test Cycle (WLTC). Engine performance, gaseous and particle matter emissions and combustion analysis from these blends were compared with those from diesel fuel. Engine performance was similar for all fuels, with slight differences in equivalence ratio and exhaust gas recirculation (EGR) rate. CO and HC emissions were increased whereas NOx emissions remained constant when blends were tested, with respect to diesel. Sooting tendency was improved since particle mass emissions were reduced despite the particle number emissions were similar to those from diesel. Combustion was quite similar between all fuels and only ignition delay was longer and combustion velocity higher for blends in comparison with diesel.

Automated summary

Waste terpenes from paper, pine, and citric industries can be used in diesel blends after hydrogenation to reduce sooting tendency. Blends of hydrogenated turpentine and orange oil at 20 vol % were tested in a diesel engine, showing similar performance, increased CO and HC emissions, and unchanged NOx emissions compared to diesel. While particle number emissions were similar to diesel, particle mass emissions were reduced, indicating improved sooting tendency. Combustion characteristics were similar, with longer ignition delay and higher combustion velocity in the blends.