**1. Introduction**

Diesel engines the world over are the major power source in the automobile transport industry and nonroad powered engines. However, because of the issue of pollution associated with diesel exhaust, particularly particulate matter (PM) and nitrogen oxide (NOX), there has been increasingly stringent regulation to control the manufacture and use of diesel engines. This has led to extensive research on improving diesel engines and fuel [1, 2]. The use of alternative fuels tops the list of measures to control diesel exhaust emissions as recommended by researcher [3]. Besides the use of alternative fuel to control and reduce emissions, other control

strategies such as exhaust gas recirculation (EGR), diesel particulate filters (DPF), selective catalytic reduction (SCR), and catalytic converter combinations have been recommended but not as stand-alone technologies [4, 5].

The transport industry and nonroad diesel engines are major contributors to global gross domestic product. Nevertheless, their use affects human health and degrades the environment. The transport industry is responsible for one third of all environmental emissions of volatile organic compounds (VOCs), including two thirds of carbon monoxide (CO) emissions [6]. Carbon dioxide (CO2) is a primary cause of global warming with 34 billion tons per year or 22% of all the global emissions per year [7], with a projected increase in 3% annually since 2011. This is projected to rise to 41 billion tons of CO2 emissions by the year 2020 [8, 9]. Diesel engines release emissions, which lead to poor air quality, acid rain, smog, haze, and climate change. These factors increase the global disease burden due to respiratory system diseases and cancer [10].

The soluble organic fraction (SOF) and volatile organic fraction (VOF) are mainly due to exhaust dilution and the cooling process from fuel or evaporating lubricating oil, due to the process of oxidation. The control of VOC emissions is with high-pressure injection system catalytic converters and positive crankcase ventilation systems. The PM emissions of VOCs arising from evaporating lubrication oil and incomplete combustion have a combined emission rate of 0.06–2.2 g/bkWh for light diesel (LD) engines compared to heavy diesel (HD) engines at 0.5–1.5 g/bkWh [11, 12]. The condensation of oxidized and pyrolyzed products of fuel molecules is the leading cause for the formation of PM emissions composed of the nucleation and accumulation modes [13]. In emerging economies, air pollution is the leading cause of thousands of premature deaths estimated at 2.4 million annually by 2009 estimates [14]. Besides the usual toxics emitted by stationary and nonroad engines, diesel engines emit toxics such as formaldehyde, acrolein, acetaldehyde, and methanol. Exposure to these toxic emissions causes eye, skin, and mucous membrane irritation, besides affecting the nervous system. Therefore, the need for environmental protection has played a role in bringing together relevant stakeholders and government agencies. These agencies include the WHO, the Organization of Economic Cooperation and Development (OECD), the Inter-Governmental Panel on Climate Change (IPCC), the Environmental Protection Agency (EPA), the European Environmental Agency (EEA), and the International Energy Agency (IEA). For example, the USA government through the EPA has established the Reciprocating Internal Combustion Engine (RICE) rules, which cover stationary and nonroad engine emission regulations [15]. These rules are out of the scope of this chapter, but future work will discuss them in line with other European Union rules [16] and other global adopted emission regulations.

In order to meet modern requirements, diesel engines are designed with complex contrary goals to operate optimally in stationary and mobile operations. This requires high torque, low emissions, and high efficiency engines. For this reason, auxiliary diesel engine components such as turbochargers, EGR, and high-pressure injection systems are utilized today. These auxiliary parts are grouped into engine operating subsystems such as air, combustion, injection, and mechanical units to meet these operating demands. Since fuel is a major determinant in engine combustion and emission characteristics, the use of alternative fuel is being encouraged as a strategy to reduce emissions. The combustion of alternative fuel is different from the combustion of diesel, which is a fossil fuel, but they too cause emission problems as has been reported in a number of studies [17, 18]. To mitigate these problems, researchers have come up with combustion control strategies such as:

**37**

**Figure 1.**

*Effects of Biodiesel Blends Varied by Cetane Numbers and Oxygen Contents on Stationary Diesel…*

Modern day passenger vehicles and stationary engines are now evaluated using driving cycles such as the New European Driving Test Cycle (NEDC) and the Federal Test Procedure (FTP) mostly as bench operated chassis dynamometer tests [31]. However, it should be remembered that at engine start conditions, after-treatment techniques report poor performance as most of them operate with catalysts that are light-off temperature dependent. At ambient temperature, most catalysts cannot attain the light-off temperature when engines are started and operated. Since the year 2000 when EURO III was implemented, the NEDC procedure has been modified to eliminate the 40 s warm up before emission sampling can take place [32]. The new development initiative for diesel exhaust emission has already been established in the United States and Japan. The last decade has seen the European Union implementing similar standards and procedures, with the rest of the world expected to also implement changes as globalization and interdependency grows. A number of requirement have been implemented in the United States to nominally reduce 85–90% of NOX, while for the Euro VI (2014), an additional reduction 65–70% of NOX to match the US standards has been accepted

The combustion of diesel fuel depends on several factors that affect engine geometry, fuel properties, compression temperatures (especially of the combustion mixture), injection strategy applied, and the existing condition of the ambient temperatures as reported by the authors of Refs. [34, 35]. High cetane number additives together with the development of high volatility fuels [36, 37] have boosted diesel engine performance. The oxygenated additives in biodiesel blend components improve the combustion process, especially the octane rating. Additionally, oxygenated additives enhance and increase the cetane number. In other words, the oxygen in the additives supports the combustion of the fuel while at the same time reducing inert material such as NOX formation in CI engines. These changes deal with the complexities of cold start, which impede engine starting at lower or subzero engine temperatures. Warm engines have a starting time delay of 1–2 s at ambient temperature conditions, compared to a low

*Requirement to reduce about 55–60% of NOX emissions for Euro V (2009) diesel to match the US Bin 8* 

• reactivity charge compression ignition (RCCI) [23]; and

• variant strategies to deal with emissions [24–30].

*DOI: http://dx.doi.org/10.5772/intechopen.92569*

as shown in **Figures 1** and **2** [33].

ambient temperature start-up time of 10 s [38, 39].

*maximum allowable emission in 45 US states [33].*


*Effects of Biodiesel Blends Varied by Cetane Numbers and Oxygen Contents on Stationary Diesel… DOI: http://dx.doi.org/10.5772/intechopen.92569*


*Numerical and Experimental Studies on Combustion Engines and Vehicles*

recommended but not as stand-alone technologies [4, 5].

strategies such as exhaust gas recirculation (EGR), diesel particulate filters (DPF), selective catalytic reduction (SCR), and catalytic converter combinations have been

the global disease burden due to respiratory system diseases and cancer [10].

Union rules [16] and other global adopted emission regulations.

• homogeneous charge compression ignition (HCCI) [19, 20];

• pre-mixed charge compression ignition (PCCI) [21, 22];

In order to meet modern requirements, diesel engines are designed with complex contrary goals to operate optimally in stationary and mobile operations. This requires high torque, low emissions, and high efficiency engines. For this reason, auxiliary diesel engine components such as turbochargers, EGR, and high-pressure injection systems are utilized today. These auxiliary parts are grouped into engine operating subsystems such as air, combustion, injection, and mechanical units to meet these operating demands. Since fuel is a major determinant in engine combustion and emission characteristics, the use of alternative fuel is being encouraged as a strategy to reduce emissions. The combustion of alternative fuel is different from the combustion of diesel, which is a fossil fuel, but they too cause emission problems as has been reported in a number of studies [17, 18]. To mitigate these problems, researchers have come up with combustion control strategies such as:

The transport industry and nonroad diesel engines are major contributors to global gross domestic product. Nevertheless, their use affects human health and degrades the environment. The transport industry is responsible for one third of all environmental emissions of volatile organic compounds (VOCs), including two thirds of carbon monoxide (CO) emissions [6]. Carbon dioxide (CO2) is a primary cause of global warming with 34 billion tons per year or 22% of all the global emissions per year [7], with a projected increase in 3% annually since 2011. This is projected to rise to 41 billion tons of CO2 emissions by the year 2020 [8, 9]. Diesel engines release emissions, which lead to poor air quality, acid rain, smog, haze, and climate change. These factors increase

The soluble organic fraction (SOF) and volatile organic fraction (VOF) are mainly due to exhaust dilution and the cooling process from fuel or evaporating lubricating oil, due to the process of oxidation. The control of VOC emissions is with high-pressure injection system catalytic converters and positive crankcase ventilation systems. The PM emissions of VOCs arising from evaporating lubrication oil and incomplete combustion have a combined emission rate of 0.06–2.2 g/bkWh for light diesel (LD) engines compared to heavy diesel (HD) engines at 0.5–1.5 g/bkWh [11, 12]. The condensation of oxidized and pyrolyzed products of fuel molecules is the leading cause for the formation of PM emissions composed of the nucleation and accumulation modes [13]. In emerging economies, air pollution is the leading cause of thousands of premature deaths estimated at 2.4 million annually by 2009 estimates [14]. Besides the usual toxics emitted by stationary and nonroad engines, diesel engines emit toxics such as formaldehyde, acrolein, acetaldehyde, and methanol. Exposure to these toxic emissions causes eye, skin, and mucous membrane irritation, besides affecting the nervous system. Therefore, the need for environmental protection has played a role in bringing together relevant stakeholders and government agencies. These agencies include the WHO, the Organization of Economic Cooperation and Development (OECD), the Inter-Governmental Panel on Climate Change (IPCC), the Environmental Protection Agency (EPA), the European Environmental Agency (EEA), and the International Energy Agency (IEA). For example, the USA government through the EPA has established the Reciprocating Internal Combustion Engine (RICE) rules, which cover stationary and nonroad engine emission regulations [15]. These rules are out of the scope of this chapter, but future work will discuss them in line with other European

**36**

Modern day passenger vehicles and stationary engines are now evaluated using driving cycles such as the New European Driving Test Cycle (NEDC) and the Federal Test Procedure (FTP) mostly as bench operated chassis dynamometer tests [31]. However, it should be remembered that at engine start conditions, after-treatment techniques report poor performance as most of them operate with catalysts that are light-off temperature dependent. At ambient temperature, most catalysts cannot attain the light-off temperature when engines are started and operated. Since the year 2000 when EURO III was implemented, the NEDC procedure has been modified to eliminate the 40 s warm up before emission sampling can take place [32]. The new development initiative for diesel exhaust emission has already been established in the United States and Japan. The last decade has seen the European Union implementing similar standards and procedures, with the rest of the world expected to also implement changes as globalization and interdependency grows. A number of requirement have been implemented in the United States to nominally reduce 85–90% of NOX, while for the Euro VI (2014), an additional reduction 65–70% of NOX to match the US standards has been accepted as shown in **Figures 1** and **2** [33].

The combustion of diesel fuel depends on several factors that affect engine geometry, fuel properties, compression temperatures (especially of the combustion mixture), injection strategy applied, and the existing condition of the ambient temperatures as reported by the authors of Refs. [34, 35]. High cetane number additives together with the development of high volatility fuels [36, 37] have boosted diesel engine performance. The oxygenated additives in biodiesel blend components improve the combustion process, especially the octane rating. Additionally, oxygenated additives enhance and increase the cetane number. In other words, the oxygen in the additives supports the combustion of the fuel while at the same time reducing inert material such as NOX formation in CI engines. These changes deal with the complexities of cold start, which impede engine starting at lower or subzero engine temperatures. Warm engines have a starting time delay of 1–2 s at ambient temperature conditions, compared to a low ambient temperature start-up time of 10 s [38, 39].

#### **Figure 1.**

*Requirement to reduce about 55–60% of NOX emissions for Euro V (2009) diesel to match the US Bin 8 maximum allowable emission in 45 US states [33].*

**Figure 2.** *Variation of NOx emission with the regulatory limit for 45 US states [33].*
