# Application of Canola Oil Biodiesel/Diesel Blends in a Common Rail Diesel Engine
## 1 Introduction  
Due to their high thermal efficiency, large power output, reliability, durability, and high fuel economy compared with gasoline engines, diesel engines are widely used in various sectors, such as industrial transportation, passenger cars, and agricultural applications, despite their disadvantages of noise and vibration. As their hydrocarbon (HC), carbon dioxide (CO\({}_{2}\)), and carbon monoxide (CO) emissions have been decreasing in exhaust emissions, diesel engines are becoming more and more popular. However, because diesel engines burn fuel in their cylinders at high temperatures and high pressures, and because the air/fuel mixture and temperature distribution are nonuniform, a diesel engine exhausts more nitrogen oxide (NOx) and particulate matter (PM) emissions than a gasoline engine [1; 2; 3; 4; 5; 6; 7]. It has been estimated that the PM emission from a diesel engine per unit of travelled distance is over 10 times higher than the emission from a gasoline engine running on unleaded gasoline fuel at the same power output [8; 9]. Furthermore, the PM and NOx emissions from diesel are strictly controlled as an important environmental issue. Because mutagens and carcinogens are present in both the gaseous and particulate components of exhaust, lung cancer has been a focus of attention as a related health risk in animal and human research [10]. Decreasing harmful exhaust emissions is becoming an increasing priority. Researchers have made substantial efforts to develop new technology to address this problem, such as reducing the PM exhaust emissions by using diesel particulate filters (DPF) or alternative fuels [11; 12], and reducing the NO\(x\) emissions by using selective catalytic reduction (SCR) [13; 14; 15] or exhaust gas recirculation (EGR) [16]. These treatment systems can effectively solve this problem, however, they reduce the diesel engine's advantages in fuel economy, and the complex settings are very expensive [17]. Hence, many researchers have become interested in studying alternative fuels. Biofuels are alternative fuels that can effectively reduce engine exhaust emissions, such as CO and PM emissions, due to the oxygen they contain, which can promote combustion in the combustion chamber. Additionally, they have energy security, nontoxicity, local availability, and recyclability [18; 19; 20]. Usually, biofuels are obtained from plants, waste oils, and animal fats through a variety of processing methods, and their fuel properties change with the different feedstocks [21; 22]. In particular, biodiesel as a fuel for diesel engines is widely appealing because it is biodegradable and nontoxic, and compared to standard fuels, it emits less greenhouse gases (GHG) and significantly reduces exhaust emissions and overall life cycle emissions of CO\({}_{2}\) from the engine when burned as a fuel. The research on biodiesel stability has been established as a top priority [23; 24; 25]. Biofuels can be used for diesel engines in a blended form with conventional diesel without modifications of the engine [26; 27; 28]. However, researchers have found a series of problems with the use of pure vegetable oils in diesel engines [29; 30]. Vegetable oils have characteristics such as high density, high viscosity, high iodine content, and low volatility. These characteristics create a series of problems when using pure vegetable oils in a diesel engine, such as engine deposits, injector coking, and piston ring sticking [31; 32; 33; 34]. These problems are prevented by mixing vegetable oil with diesel fuel, which can also improve the combustion characteristics. With transesterification, biodiesel can achieve almost the same performance as diesel fuel [35; 36; 37]. In addition, canola oil is one kind of vegetable biodiesel that can produce more oil per unit of land area compared to other oil sources [38]. [PERSON] et al. [39] found that using biodiesel can reduce engine wear than that of diesel fuel. [PERSON] et al.