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Diesel fuel lubricity has continued to be a topic of interest for the suppliers of diesel engines, diesel fuel injection equipment, diesel fuel and diesel fuel additives. The term “lubricity” has become commonly used to mean the ability of a diesel fuel to prevent or minimize wear in diesel fuel injection equipment systems that rely on the fuel to provide lubrication. Distributor and rotary type injection pumps are examples of systems that rely totally on the fuel for lubrication. These systems are commonly used in light and medium duty diesel engines. Shell Canada has been investigating the lubricity performance of diesel fuels for a number of years. We have continued to evaluate the lubricity performance of various diesel test fuels and additives in a specifically designed distributor type pump rig that has been described previously (1, 2, 3).

The exhaust emissions from a single-cylinder version of a heavy-duty diesel engine with exhaust gas recirculation (EGR) were studied using 12 diesel fuels derived from oil sands and conventional sources. The test fuels were blended from 22 refinery streams to produce four fuels (two from each source) at three different total aromatic levels (10, 20, and 30% by mass). The cetane numbers were held constant at 43. Exhaust emissions were measured using the AVL eight-mode steady-state test procedure. PM emissions were accurately modeled by a single regression equation with two predictors, total aromatics and sulphur content. Sulphate emissions were found to be independent of the type of sulphur compound in the fuel. NOx emissions were accurately modeled by a single regression equation with total aromatics and density as predictor variables. PM and NOx emissions were significantly significantly affected by fuel properties, but crude oil source did not play a role.

Many modern diesel fuel injection equipment designs rely totally on the fuel to provide lubrication. The ability of a diesel fuel to lubricate diesel fuel injection equipment has become commonly referred to as its “lubricity”. If a diesel fuel has insufficient lubricity then the performance of the fuel injection equipment can be compromised resulting in reduced durability and increased vehicle emissions. We have been studying diesel fuel lubricity since the early 1990s using a test rig. The test rig consists of a motored distributor type fuel injection pump, injectors and a fuel handling/circulation system. This paper reviews test rig results on a total of twenty three different base fuels. The pump test rig results are compared to the inspection properties of the test fuels and conclusions derived.

The durability and performance of diesel fuel injection equipment in actual use continues to be a concern for the manufacturers of diesel powered equipment, diesel fuel injection equipment suppliers and diesel fuel suppliers This concern has been caused by recent changes to both the equipment and the diesel fuel driven by environmental legislation The term “lubricity” has become commonly used to describe the ability of a diesel fuel to prevent or minimise wear in diesel fuel injection equipment Of particular interest are distributor and rotary type fuel injection pumps that rely totally on the fuel for lubrication These pump types are commonly used in light and medium duty diesel engines Earlier work has shown that fuels with good low temperature properties have inherently poorer lubricity performance than summer quality diesel fuels (1, 2)* Due to the need for such fuels in Canada we have been investigating the lubricity performance of winter diesel fuels for a number of years Most recently we have studied the lubricity performance of various fuels and additives in rotary type pumps and related these results to the test fuel properties, including lubricity as measured in a number of current lab bench tests

In the last few years there have been sporadic complaints regarding field failures of diesel fuel injection equipment. Upon investigation these complaints have been associated with: i) rotary or distributor type pumps as used in light and medium duty diesel engines, and ii) the use of “winter” grade diesel fuels or diesel fuels that have been altered to meet the requirements of environmental regulations. Rotary and distributor type diesel fuel pumps rely totally on the fuel for lubrication. The fuel's ability to prevent or minimize wear in these types of pumps is important. This ability has recently been referred to as the fuel's “lubricity”. Shell Canada has been investigating this issue for the past few years. Recently we have investigated the “lubricity” performance of various diesel fuels using two diesel fuel pump endurance rigs. One rig consists of two rotary type pumps, the other two distributor type pumps.

A combustion-based analytical method, initially developed by the Southwest Research Institute (SwRI) and referred to as the Constant Volume Combustion Apparatus (CVCA), has been further researched/developed by an SwRI licensee (Advanced Engine Technology Ltd.). This R&D has resulted in a diesel fuel Ignition Quality Tester (IQT) that permits rapid and precise determination of the ignition quality of middle distillate and alternative fuels. Its features, such as low fuel volume requirement, complete test automation, and self-diagnosis, make it highly suitable for commercial oil industry and research applications. A preliminary investigation, reported in SAE paper 961182, has shown that the IQT results are highly correlated to the ASTM D-613 cetane number (CN). The objective of this paper is to report on efforts to further refine the original CN model and report on improvements to the IQT fuel injection system.

The influence of fuel aromatics type on the particulate matter (PM) and NOx exhaust emissions of a heavy-duty, single-cylinder, DI diesel engine was investigated. Eight fuels were blended from conventional and oil sands crude oil sources to form five fuel pairs with similar densities but with different poly-aromatic (1.6 to 14.6%) or total aromatic (14.3 to 39.0%) levels. The engine was tuned to meet the U.S. EPA 1994 emission standards. An eight-mode, steady-state simulation of the U.S. EPA heavy-duty transient test procedure was followed. The experimental results show that there were no statistically significant differences in the PM and NOx emissions of the five fuel pairs after removing the fuel sulphur content effect on PM emissions. However, there was a definite trend towards higher NOx emissions as the fuel density, poly-aromatic and total aromatic levels of the test fuels increased.