Comparison of HRD and Petro Diesel in Industrial Engine Applications

Renewable fuels are seen as a key enabler on the path to a lower carbon future. A low greenhouse gas fuel of particular interest is hydrotreated renewable diesel (HRD), also known as hydrotreated vegetable oil (HVO). HRD is of interest because it is a drop-in replacement to existing petroleum fuels used in diesel engines. An experimental investigation was undertaken to evaluate combustion characteristics of HRD versus a standard petroleum diesel. The work was carried out using a 2.5-liter fully instrumented single-cylinder research engine. This engine was chosen because it provides a very precise view of the difference in combustion and emissions of the fuels. Results represent the difference in combustion characteristics of the fuels, rather than potential differences in engine performance seen in a production engine, as each particular engine model will react a bit differently to the changes in combustion. The engine was operated according to three ISO 8178-4 test cycles: C1, D2, and E3. These test cycles represent off-highway machines, generator sets, and marine propulsion, respectively. A set of hypotheses was tested, these were based on data reported in the literature and expert opinion. As expected in the hypotheses, there were reductions in noise, particulate matter emissions, and oxides of nitrogen. Increases in hydrocarbon and carbon monoxide emissions seen in some cases were unexpected results. Results presented and discussed also include analytical evaluation of the properties of the fuels, including properties specified in ASTM D975 (Standard Specification for Diesel Fuel Oils).