Steady-State Biodiesel Blend Estimation via a Wideband Oxygen Sensor

Abstract

A substantial opportunity exists to reduce carbon dioxide (CO2) emissions, as well as dependence on foreign oil, by developing strategies to cleanly and efficiently use biodiesel, a renewable domestically available alternative diesel fuel. However, biodiesel utilization presents several challenges, including decreased fuel energy density and increased emissions of smog-generating nitrogen oxides (NOx). These negative aspects can likely be mitigated via closed-loop combustion control provided the properties of the fuel blend can be estimated accurately, on-vehicle, in real-time. To this end, this paper presents a method to practically estimate the biodiesel content of fuel being used in a diesel engine during steady-state operation. The simple generalizable physically motivated estimation strategy presented utilizes information from a wideband oxygen sensor in the engine’s exhaust stream, coupled with knowledge of the air-fuel ratio, to estimate the biodiesel content of the fuel. Experimental validation was performed on a 2007 Cummins 6.7 l ISB series engine. Four fuel blends (0%, 20%, 50%, and 100% biodiesel) were tested at a wide variety of torque-speed conditions. The estimation strategy correctly estimated the biodiesel content of the four fuel blends to within 4.2% of the true biodiesel content. Blends of 0%, 20%, 50%, and 100% were estimated to be 2.5%, 17.1%, 54.2%, and 96.8%, respectively. The results indicate that the estimation strategy presented is capable of accurately estimating the biodiesel content in a diesel engine during steady-state engine operation. This method offers a practical alternative to in-the-fuel type sensors because wideband oxygen sensors are already in widespread production and are in place on some modern diesel vehicles today.

Chemical sensor systems for emission control from combustions

“…Sensors e.g. for oxygen and nitrogen oxide monitoring in diesel exhausts are commercially available and still an active research field [1,2]. A number of particulate sensors are available which detect particles according to size and mass or volume concentration, improvements are reported in articles as well as the use of such equipments [3,4].…”

Composed adaptive control of a bio-diesel engine with EGR & VGT

“…Thus considering the above equations (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and the definition of e y = y − y, one obtainṡ…”

“…Under the proposed composed adaptive robust control which is defined in(10) for the considering system (11) …”

“…Biodiesel which can be produced from a wide variety of domestically available feedstocks (such as vegetable oils and animal fats) is a renewable, alternative diesel fuel [11]. The referred oils and animal fats are reacted with an alcohol typically of methanol in the presence of catalyst to produce glycerin and fatty acid esters.…”

Adaptive Observer for Joint Estimation of Oxygen Fractions and Blend Level in Biodiesel Fueled Engines

“…An approach based on the common-rail pressure signal for identifying the fuel types was developed in [5]. Snyder et al [6] pointed out that biodiesel is an oxygenated fuel, which differs from the conventional diesel. In addition, the difference can be detected by a wideband oxygen or UEGO sensor at the exhaust manifold.…”