Engine Performance and Exhaust Emissions of Cottonseed Oil Biodiesel

The objective of this research was to determine the relationship between engine performance and emissions of cottonseed oil biodiesel used in a 14.2 kW diesel engine. When using cottonseed oil biodiesel blends, CO, total hydrocarbon (THC), NOx, and SO2 emissions decreased as compared to petroleum diesel. Carbon dioxide emissions had no definitive trend in relation to cottonseed oil biodiesel blends. Carbon monoxide emissions increased by an average 15% using B5 and by an average of 19% using B100. Hydrocarbon emissions decreased by 14% using B5 and by 26% using B100. Nitrogen oxide emissions decreased by four percent with B5, five percent with B20, and 14% with B100. Sulfur dioxide emissions decreased by an average of 86% using B100, and by 94% using B50 blended with ultra-low sulfur diesel. The difference between peak output power when using biodiesel and when using diesel was insignificant in blends less than B40. Peak brake power when using B100 was about five percent lower than for diesel fuel. Pure cottonseed oil biodiesel achieved and maintained a peak corrected brake power of 13.1 kW at speeds of 2990, 2875, and 2800 rpm at loads of 41.3, 42.7, and 43.8 N-m. Using B5 produced a peak power of 13.6 kW at 2990 rpm and 43.9 N-m and at 2800 rpm and 46.7 N-m, while using B20 produced a peak power of 13.4 kW at 2990 rpm and 43.7 N-m. Brake-specific fuel consumption at peak load and torque when using B100 was 1238 g/kW-h. Brake-specific fuel consumption at peak power and loads using B5 and B20 were 1276 and 1155 g/kW-h. Introduction With the increased emphasis on the need for clean, renewable fuels, it is imperative to fully understand the operational characteristics of biodiesel. For many years, petroleum has been the primary source for diesel fuels (Schumacher et al., 2001). However, in recent years the supply of petroleum has slowed, while the need for petroleum fuels has substantially increased. According to the Environmental Protection Agency, or EPA, (2004), non-road diesel engines are significant contributors of air pollution in the United States. The primary pollutants of interest include carbon monoxide (CO), particulate matter (PM), nitrogen oxides (NOx), and sulfur oxides (SOx). The EPA has adopted new emissions standards for non-road diesel engines and sulfur reductions in non-road diesel fuel, effective August 30, 2004. Sulfur in diesel fuel acts as an engine lubricant. If sulfur is removed from the diesel fuel, it will reduce fuel lubricity. While newer engines may be designed to handle low sulfur fuel, older engines may not. For example, fueling an older model engine with low sulfur diesel for an extended period of time may result in injectors sticking. Biodiesel is one solution to the removal of sulfur in diesel fuel due to its lubricating ability. Biodiesel is a cleaner-burning, renewable fuel that is compatible with petroleum diesel and can be produced domestically (NBB, 2006). While there is a wealth of available data regarding some types of biodiesel (Munoz et al., 2004), there is little data regarding the effect of cottonseed oil (CSO) biodiesel on diesel engine performance and exhaust emissions. According to the National Cottonseed Production Association, or NCPA, (2002) cottonseed oil ranks third in volume of oil produced in the United States behind soybean and corn oil. Recent trends have shown a decrease in desire to use CSO as food oil, since CSO contains trans-fatty acids. This trend has an inverse effect on the desire and availability of CSO to be used in biodiesel production. With the large amount of cotton produced in the southern United States, and the growing need for utilizing agricultural byproducts, it is important to investigate engine performance using biodiesel from cottonseed oil, as well as analyzing the exhaust emissions produced. Objectives The objective of this research is to gain a better understanding of cottonseed oil biodiesel by: • Determining the relationship between diesel engine performance and the percentage of cottonseed oil biodiesel in fuel blends; 556 2008 Beltwide Cotton Conferences, Nashville, Tennessee, January 8-11, 2008