**1. Introduction**

In the frame of complying with the emission regulations that become day by day more and more stringent, researchers have focused their interest on areas of fuel injection control strategies, exhaust gas recirculation, exhaust gas posttreatment devices, and also on areas of alternative fuels.

four-cylinder turbocharged diesel engine. The results showed that the use of WCO resulted in higher brake specific fuel consumption with regard to the exhaust emissions; the use of WCO

duced by biodiesel (100% v/v) was lower compared to that of diesel fuel. Can [25] experimentally investigated the combustion development of a single-cylinder diesel engine fuelled with

smoke and HC was found. Cheung et al. [26] analyzed the impact on the emissions from a diesel engine at fixed engine speed fuelled with diesel blended with different proportions of biodiesel from WCO. The results showed that biodiesel leads to a reduction in HC, CO, and particulate

the effect of diesel operating conditions on the particle size emitted by a diesel engine operating with WCO biodiesel. They found more particles with larger size at lower engine speed; primary particles tend to form at lower engine load. Hwang et al. [28] investigated the combustion and emission characteristics of WCO and conventional diesel fuel in an optically accessible diesel engine. WCO had the benefits in CO, HC, and PM reduction at low load. In the high engine

Although the research on biodiesel combustion and emissions is considerable and many studies are related to the usage of WCO in diesel engines, they mainly focused on multicylinder-diesel engine of large displacement. Only some works are devoted to light-duty diesel engines, designed for agricultural purpose, and the results are mainly related to a fixed value

The main aim of this research is to analyze in detail the impact of WCO used in different percentages with diesel oil in an up-to-date light and compact, common rail diesel engine whose main application is in microcars and in urban vehicles. A comprehensive experimental activity was performed in the engine complete operative field in order to characterize the engine

influence of WCO content in the blend on the particle emissions was also investigated, in

A common-rail water-cooled two-cylinder diesel engine was tested in this study. Its main technical data are presented in **Table 1**. The engine was connected to an asynchronous motor (Siemens 1PH7, nominal torque 360 Nm, power 70 kW) and was installed in the test bed of the

Torque measurement was carried out by means of HBM T12 (it is a strain gauge transducer

The in-cylinder pressure was measured with a piezoelectric transducer AVL GU13P.

WCO blended in 5 and 10% with diesel fuel. An increase in NO<sup>x</sup>

mass concentration and number concentrations, but an increase in NO<sup>x</sup>

load, the emission characteristic of WCO was deteriorated than that of diesel.

, CO, CO2

and HC; under most of the operating conditions, NO<sup>x</sup>

Effect of Waste Cooking Oil Biodiesel Blends on Performance and Emissions...

, HC, and soot concentration were analyzed. The

pro-

21

emissions and a decrease in

http://dx.doi.org/10.5772/intechopen.69740

. Man et al. [27] studied

generally resulted in a lower CO2

of engine speed and load.

performance and emissions. NO<sup>x</sup>

**2. Apparatus and tests**

**2.1. Experimental setup**

with an optical encoder).

terms of soot particles' size distributions.

Engineering Department at Roma Tre University.

AVL Fuel Balance 733 was used for fuel consumption measurement.

Alternative fuels from vegetable oils and animal fats have been proposed for a partial and total replacement of diesel fuel to reduce the environmental impact in terms of air pollution and dependence on fossil fuel.

Among these fuels, biodiesel from vegetable oils has received great attention for its renewability and its potential to reduce greenhouse gas emissions and soot formation [1–4].

Experimental investigations have highlighted that biodiesel used in blends with diesel is responsible for a reduction in unburned hydrocarbon, carbon monoxide, and particle emissions due to the increased oxygen content in the fuel [4–8]. In regard to NO<sup>x</sup> emission, somehow contradictory conclusions were found, since there are numerous factors, each has its own relative importance according to the engine technology and operating conditions of the blended fuel [9–13]. Physical properties, chemical composition, and structure of the biodiesel alter the fuel injection and ignition process, and then the combustion development and the engine exhaust emissions [14–18]. Many studies proved that biodiesel feedstock and blend ratios have a large impact on obtained results. Peng [2] tested various types of biodiesel on a turbocharged diesel engine; he found smoke opacity, CO and HC decreased, but fuel consumption increased compared to petrol diesel. Serrano et al. [11] analyzed the behavior of an EURO 5 engine fuelled with two biodiesel blends (7 and 20% v/v). Fuel consumption was not consistently increased with biodiesel; NO<sup>x</sup> emission with biodiesel use did not present significant rise. Yehliu et al. [19] investigated the impact of fuel properties and injection strategy on the combustion process and soot emission. Three fuels were tested on a turbocharged diesel engine, and particle size distribution was measured. Ajtai et al. [20] studied the effect of fuel type and engine condition on number and size distribution of diesel soot. They found that the biodiesel content in the total fuel amount can modify the characteristics of the exhaust particles.

Among all suitable biodiesel fuels, waste cooking oil (WCO) has been considered a promising alternative to vegetable fresh oil because of its reduced raw material cost (the price of WCO is two to three times cheaper than virgin vegetable oils [21]). Moreover, WCO conversion into fuel offers the advantage of eliminating the environmental impact caused by its disposal. Previous studies demonstrated the suitability of WCO as a biofuel. Attia and Hassaneen [12] studied the effect of various WCO blends on the performance of a single-cylinder diesel engine. The best value of a brake specific fuel consumption was attained at blended fuel containing 20% of WCO. A range of blending ratio between 20 and 50% v/v showed the best environmental behavior. Gopal et al. [22] investigated the performance and emission characteristics of a singlecylinder diesel engine designed for agricultural purpose fuelled with WCO and its blends. The study revealed that WCO has lower CO, HC, and smoke opacity than diesel. On the other hand, NO<sup>x</sup> and specific fuel consumption were higher than diesel. An et al. [23, 24] evaluated the influence of WCO biodiesel/blends on combustion and exhaust emission characteristics of a four-cylinder turbocharged diesel engine. The results showed that the use of WCO resulted in higher brake specific fuel consumption with regard to the exhaust emissions; the use of WCO generally resulted in a lower CO2 and HC; under most of the operating conditions, NO<sup>x</sup> produced by biodiesel (100% v/v) was lower compared to that of diesel fuel. Can [25] experimentally investigated the combustion development of a single-cylinder diesel engine fuelled with WCO blended in 5 and 10% with diesel fuel. An increase in NO<sup>x</sup> emissions and a decrease in smoke and HC was found. Cheung et al. [26] analyzed the impact on the emissions from a diesel engine at fixed engine speed fuelled with diesel blended with different proportions of biodiesel from WCO. The results showed that biodiesel leads to a reduction in HC, CO, and particulate mass concentration and number concentrations, but an increase in NO<sup>x</sup> . Man et al. [27] studied the effect of diesel operating conditions on the particle size emitted by a diesel engine operating with WCO biodiesel. They found more particles with larger size at lower engine speed; primary particles tend to form at lower engine load. Hwang et al. [28] investigated the combustion and emission characteristics of WCO and conventional diesel fuel in an optically accessible diesel engine. WCO had the benefits in CO, HC, and PM reduction at low load. In the high engine load, the emission characteristic of WCO was deteriorated than that of diesel.

Although the research on biodiesel combustion and emissions is considerable and many studies are related to the usage of WCO in diesel engines, they mainly focused on multicylinder-diesel engine of large displacement. Only some works are devoted to light-duty diesel engines, designed for agricultural purpose, and the results are mainly related to a fixed value of engine speed and load.

The main aim of this research is to analyze in detail the impact of WCO used in different percentages with diesel oil in an up-to-date light and compact, common rail diesel engine whose main application is in microcars and in urban vehicles. A comprehensive experimental activity was performed in the engine complete operative field in order to characterize the engine performance and emissions. NO<sup>x</sup> , CO, CO2 , HC, and soot concentration were analyzed. The influence of WCO content in the blend on the particle emissions was also investigated, in terms of soot particles' size distributions.
