**2. Apparatus and tests**

## **2.1. Experimental setup**

**1. Introduction**

native fuels.

and dependence on fossil fuel.

20 Improvement Trends for Internal Combustion Engines

with biodiesel; NO<sup>x</sup>

hand, NO<sup>x</sup>

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 alter-

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

Among these fuels, biodiesel from vegetable oils has received great attention for its renew-

Experimental investigations have highlighted that biodiesel used in blends with diesel is responsible for a reduction in unburned hydrocarbon, carbon monoxide, and particle emissions

tradictory 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

[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

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

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

emission with biodiesel use did not present significant rise. Yehliu et al.

emission, somehow con-

ability and its potential to reduce greenhouse gas emissions and soot formation [1–4].

due to the increased oxygen content in the fuel [4–8]. In regard to NO<sup>x</sup>

total fuel amount can modify the characteristics of the exhaust particles.

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 Engineering Department at Roma Tre University.

Torque measurement was carried out by means of HBM T12 (it is a strain gauge transducer with an optical encoder).

AVL Fuel Balance 733 was used for fuel consumption measurement.

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


**Table 1.** Engine specifications.

The engine exhaust emissions (CO, CO2 , HC, O2 , and NO<sup>x</sup> expressed as NO equivalent) were measured with Bosch BEA352. AVL particle counter (APC) and AVL micro soot sensor were used to measure the nonvolatile particle number concentration in the size range 23 nm–2.5 µm and the soot concentration in the engine exhaust gas, respectively. Particulate matter size was measured through Cambustion DMS500. This device uses a classifier column to compute the particle size distribution in the range 5 nm–1 µm, with a size resolution of 16 channels per decade. Exhaust gas passes first through a cyclone separator in order to remove particles above the measurement range (1 µm). Two stages of dilution are applied before the sample gas passes through a corona charger and into the classifier column. Primary and second dilution rates were set to 5:1 and 400:1, respectively. The charged particles flow within a particle-free sheath flow and are deflected toward grounded electrometer rings by their repulsion from a central high voltage rod. Their landing position is a function of their charge and their aerodynamic drag. Further details may be found in Ref. [29].

a transesterification process. The resulting raw biodiesel, coming from poor raw material, was distilled in order to comply with the reference specifications of biodiesel (EN 14214). Details of the procedure may be found in Ref. [31]. The properties of the biodiesel and ultralow-sulfur diesel (ULSD) are listed in **Table 2**. The chemical composition of WCO is reported in **Table 3**.

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

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

23

Since the aim of this work was to investigate the potential use of biodiesel blends in a small displacement diesel engine, some preliminary investigations were performed with the objective of selecting the maximum percentage of WCO in the blend that was able to be tested without the need of modification to the engine hardware. It was established that 40% of WCO in the blend was the highest quantity of biodiesel that could be tested, since higher percentage of biodiesel in the blend caused a degradation of the rubber hoses/seals in the engine fuel system. The experimentation was thus performed with a biodiesel percentage lower than 40% by volume: standard ultralow-sulfur diesel, B20 (80% ULSD and 20% biodiesel, by volume), and B40 (60% ULSD and 40% biodiesel, by volume) were tested. This allowed the investigated blends to be ready for use in actual engine. Before each new fuel was tested, sufficient time

was given to the engine to consume the remaining fuel in the supply system.

at 15°C] 830 877

Viscosity [cSt at 40°C] 2.5 4.4 Lower heating value [MJ/kg] 43.1 37.1 Cetane number 52 56

Engine speed was varied in the engine complete operative range (2400–3600 rpm).

Load condition was varied in the field 50–80% as regards the available torque at full-load condition evaluated using diesel fuel. The maximum value was established by testing the engine with the different blends and by computing the load that are able to ensure the same value

**ULSD Biodiesel**

**2.3. Experiments**

**Figure 1.** Engine setup.

for all the tested fuels.

**Table 2.** Biodiesel and ULSD fuel properties.

Density [kg/m<sup>3</sup>

The engine speed was measured using an angular sensor (AVL 364C) with 2880 pulses/ revolution.

**Figure 1** shows the complete engine setup.

The sampling frequency was varied according to the engine speed in order to ensure a fixed angular resolution of the signals.

Data acquisition was controlled by means of LabVIEW software, by using a custom program [30].

#### **2.2. Fuel**

A second-generation biodiesel was used in the experimentation. It was obtained starting from a mixture of waste cooking oils. Due to its poor quality, it required some treatments in order to become similar to a product obtained from refined vegetable oils. A first-stage self-cleaning disk separator was used to remove 90% of the water containing the water-soluble matter and solids; a second-stage disk separator machine was used to remove the left over water. Physical deacidification was also needed to remove free fatty acids (FFA) due to product deterioration as a consequence of the use in food cooking. The neutralized products were then converted via

**Figure 1.** Engine setup.

a transesterification process. The resulting raw biodiesel, coming from poor raw material, was distilled in order to comply with the reference specifications of biodiesel (EN 14214). Details of the procedure may be found in Ref. [31]. The properties of the biodiesel and ultralow-sulfur diesel (ULSD) are listed in **Table 2**. The chemical composition of WCO is reported in **Table 3**.

#### **2.3. Experiments**

The engine exhaust emissions (CO, CO2

**Table 1.** Engine specifications.

Cylinders 2 Displacement 440 cm<sup>3</sup> Bore 68 mm Stroke 60.6 mm Compression ratio 20:1

22 Improvement Trends for Internal Combustion Engines

Maximum power 6.7 kW @ 3600 rpm Maximum torque 20 Nm @ 2400 rpm

Further details may be found in Ref. [29].

**Figure 1** shows the complete engine setup.

angular resolution of the signals.

revolution.

[30].

**2.2. Fuel**

, HC, O2

**Engine type Common rail, naturally aspirated, water-cooled**

measured with Bosch BEA352. AVL particle counter (APC) and AVL micro soot sensor were used to measure the nonvolatile particle number concentration in the size range 23 nm–2.5 µm and the soot concentration in the engine exhaust gas, respectively. Particulate matter size was measured through Cambustion DMS500. This device uses a classifier column to compute the particle size distribution in the range 5 nm–1 µm, with a size resolution of 16 channels per decade. Exhaust gas passes first through a cyclone separator in order to remove particles above the measurement range (1 µm). Two stages of dilution are applied before the sample gas passes through a corona charger and into the classifier column. Primary and second dilution rates were set to 5:1 and 400:1, respectively. The charged particles flow within a particle-free sheath flow and are deflected toward grounded electrometer rings by their repulsion from a central high voltage rod. Their landing position is a function of their charge and their aerodynamic drag.

The engine speed was measured using an angular sensor (AVL 364C) with 2880 pulses/

The sampling frequency was varied according to the engine speed in order to ensure a fixed

Data acquisition was controlled by means of LabVIEW software, by using a custom program

A second-generation biodiesel was used in the experimentation. It was obtained starting from a mixture of waste cooking oils. Due to its poor quality, it required some treatments in order to become similar to a product obtained from refined vegetable oils. A first-stage self-cleaning disk separator was used to remove 90% of the water containing the water-soluble matter and solids; a second-stage disk separator machine was used to remove the left over water. Physical deacidification was also needed to remove free fatty acids (FFA) due to product deterioration as a consequence of the use in food cooking. The neutralized products were then converted via

, and NO<sup>x</sup>

expressed as NO equivalent) were

Since the aim of this work was to investigate the potential use of biodiesel blends in a small displacement diesel engine, some preliminary investigations were performed with the objective of selecting the maximum percentage of WCO in the blend that was able to be tested without the need of modification to the engine hardware. It was established that 40% of WCO in the blend was the highest quantity of biodiesel that could be tested, since higher percentage of biodiesel in the blend caused a degradation of the rubber hoses/seals in the engine fuel system. The experimentation was thus performed with a biodiesel percentage lower than 40% by volume: standard ultralow-sulfur diesel, B20 (80% ULSD and 20% biodiesel, by volume), and B40 (60% ULSD and 40% biodiesel, by volume) were tested. This allowed the investigated blends to be ready for use in actual engine. Before each new fuel was tested, sufficient time was given to the engine to consume the remaining fuel in the supply system.

Engine speed was varied in the engine complete operative range (2400–3600 rpm).

Load condition was varied in the field 50–80% as regards the available torque at full-load condition evaluated using diesel fuel. The maximum value was established by testing the engine with the different blends and by computing the load that are able to ensure the same value for all the tested fuels.


**Table 2.** Biodiesel and ULSD fuel properties.


**Table 3.** Biodiesel composition.

The data acquisition started after the engine warm-up in order to let the engine reach nominally stationary conditions. For each running condition, 25 engine cycles were used to average the signal, thus to attenuate the engine cycle irregularities (the increase in this number did not change the feature of the trends).
