*3.3.1. Gas chromatograph conditions*

One micro litre (1 μl) of birrea biodiesel sample extract was injected into the system using an auto-injector. The injector temperature was set at 2600 C in the splitless mode. Helium was used as the carrier gas at a flow rate of 1ml/min. Separation was achieved using a 30 meter DB5 – MS column. The oven temperature was kept at the initial 1000 C for 2 minutes, and then gradually increased from 1000 C to 2900 C at a rate of 100 C per minute. The total run time was approximately 35 minutes.

#### *3.3.2. Mass spectrometer conditions*

The mass spectrometer (MS) conditions that were employed were a positive polarity of elec‐ tron ionisation (EI), a source temperature of 1800 C, and an emission current of 359μA. Other MS conditions including electron energy and resolution were set by the system's auto tune function. Detection was by the micro channel plate detector (MCP) whose voltage was set at 2700 V. The sample composition was identified and quantified using the NIST (2005) mass spectral library using a combination of the Masslynx acquisition /data analysis software and the AMDIS by NIST.

#### **3.4. Viscosity analysis**

Birrea biodiesel and petroleum diesel were analyzed using a Fungilab Premium Series (PREL 401024) viscometer coupled to a Thermo Fisher Scientific heating bath circulator. The heating bath circulator was three-quarter (¾) filled with distilled water. 3ml of both fuel samples were weighed in order to determine their densities. The viscometer was setup with the appropriate spindle and heating jacket. The LCP (low centipoise) spindle was selected for these experiments since low viscosity fluids were analyzed. The spindle was connected and the machine calibrated with the density of the fluid to be tested and the appropriate speed for the spindle. After appropriately assembling the apparatus, the sample to be tested was added in such a way that the spindle was completely submerged. The instrument was then run, with the heating bath turned on and set to 950 C. The spindle speed (RPM) could be varied based on the torque values, with the ideal range being 60-95%. Sample viscosity read‐ ings were then recorded at temperature intervals of 50 C from room temperature to 600 C as hot water was circulating between the heating bath and the heating jacket of the viscometer. The Data logger application software was used to download to a personal computer the ex‐ periment data from the viscometer for storage and analysis.

#### **3.5. Acid value determination**

composition analysis is the Waters GCT premier Time of Flight (TOF) mass spectrometer (MS) coupled to the Agilent 6890N gas chromatograph (GC) system. In addition, the Na‐ tional Institute for Standards and Technology (NIST) developed Automated Mass Spectral Deconvolution and Identification System (AMDIS) software package, (chemdata.nist.gov/ massspc/ amdis) was used for peak identification. The Automated Mass Spectral Deconvo‐ lution and Identification System extracts spectra for individual components in a GC-MS data file and identifies target compounds by matching these spectra against a reference li‐

One micro litre (1 μl) of birrea biodiesel sample extract was injected into the system using an

used as the carrier gas at a flow rate of 1ml/min. Separation was achieved using a 30 meter

The mass spectrometer (MS) conditions that were employed were a positive polarity of elec‐

MS conditions including electron energy and resolution were set by the system's auto tune function. Detection was by the micro channel plate detector (MCP) whose voltage was set at 2700 V. The sample composition was identified and quantified using the NIST (2005) mass spectral library using a combination of the Masslynx acquisition /data analysis software and

Birrea biodiesel and petroleum diesel were analyzed using a Fungilab Premium Series (PREL 401024) viscometer coupled to a Thermo Fisher Scientific heating bath circulator. The heating bath circulator was three-quarter (¾) filled with distilled water. 3ml of both fuel samples were weighed in order to determine their densities. The viscometer was setup with the appropriate spindle and heating jacket. The LCP (low centipoise) spindle was selected for these experiments since low viscosity fluids were analyzed. The spindle was connected and the machine calibrated with the density of the fluid to be tested and the appropriate speed for the spindle. After appropriately assembling the apparatus, the sample to be tested was added in such a way that the spindle was completely submerged. The instrument was

varied based on the torque values, with the ideal range being 60-95%. Sample viscosity read‐

hot water was circulating between the heating bath and the heating jacket of the viscometer. The Data logger application software was used to download to a personal computer the ex‐

C at a rate of 100

C in the splitless mode. Helium was

C, and an emission current of 359μA. Other

C. The spindle speed (RPM) could be

C as

C from room temperature to 600

C per minute. The total run time

C for 2 minutes, and

brary, in this case the NIST library.

192 Advances in Internal Combustion Engines and Fuel Technologies

*3.3.1. Gas chromatograph conditions*

then gradually increased from 1000

was approximately 35 minutes.

*3.3.2. Mass spectrometer conditions*

the AMDIS by NIST.

**3.4. Viscosity analysis**

auto-injector. The injector temperature was set at 2600

tron ionisation (EI), a source temperature of 1800

then run, with the heating bath turned on and set to 950

ings were then recorded at temperature intervals of 50

periment data from the viscometer for storage and analysis.

DB5 – MS column. The oven temperature was kept at the initial 1000

C to 2900

Acid value measurements of diesel sample extracts were carried out by titration technique according to ASTM D664 standard test method [30]. Based on the same standard 125 ml of solvent, consisting of 50% isopropyl alcohol and 50% toluene was prepared in a 600 ml beaker. 5 g of sample was then added to the beaker, followed by 2 ml of phenolphthalein indicator. The solutions were titrated with 0.1M KOH to the first permanent pink colour. Three titrations were carried out for each of the four sample extracts and the average titra‐ tion values determined. The acid values were determined using equation 2 and percentage of free fatty acids using equation 3.

$$\text{Acid value, } \text{ AV} = \frac{56.1 \times N}{W} \times Average \text{ Titration Value} \tag{2}$$

Where, 56.1 = molecular weight of KOH

N = molarity of the base

W = weight of sample in grams

$$\text{Free Fatty Aicsds (\%)}=0.5 \times AV \tag{3}$$

#### **3.6. Energy content**

The calorific values of birrea biodiesel and petroleum diesel (for comparison purposes) sam‐ ples were determined using the IKA C200 Calorimeter system whose main components in‐ clude the basic device, decomposition vessel, ignition adapter, combustion crucible and oxygen filling point. The system has automatic data acquisition through the CalWin calo‐ rimeter software which handles calculations for the calorific values of samples.

#### *3.6.1. Calorimeter conditions*

To determine the heating values of samples, 3ml of sample extract were weighed and placed in a combustion crucible at a temperature of approximately 22. The crucible was then closed up inside a decomposition vessel, which in turn was filled with oxygen at a pressure of 30 bars for 30 seconds to ensure adequate oxygen for combustion processes. The cooling water in the tank fillers was kept at initial temperature of within 180 C – 240 C range. The oxygenfilled decomposition vessel was inserted into the measuring cell that is equipped with a magnetic stirrer. The cell cover was then closed for the test to commence. Total run time for each experiment was 8.2 minutes.

#### **3.7. Engine performance analysis**

The engine performance test was conducted on a TD43F engine test rig. The test rig is water cooled four-stroke diesel engine that is directly coupled to an electrical dynamom‐ eter as demonstrated by figure 3. The dynamometer was used for engine loading. In ad‐ dition to the conventional engine design, the engine incorporates variable compression design feature which allows the compression ratio to be varied from 5:1 to 18:1. The lay‐ out of the experimental setup is shown in Fig. 3, while engine specifications are present‐ ed in Table 2.

**Parameter Specification** Make Farymann Type A30

Number of cylinders 1 Cylinder bore 95 mm Stroke 82 mm Swept volume 582 cc

Max Power 9.5kW Max torque 45Nm

**Table 2.** Engine Specifications

**3.8. Emissions measurement**

Ignition timing 300 BTDC to 100 ATDC Choke sizes 19, 21, 23, 25mm

Legend. BTDC: Before Top Dead Centre; ATDC: After Top Dead Centre. Source: [31]

Dynamometer d.c motor 5-7kW 2500 rpm with thermostat

Compression ratio Variable 5:1 to 11:1(Petrol), 12:1 to 18:1(Diesel)

Sclerocarya Birrea Biodiesel as an Alternative Fuel for Compression Ignition Engines

http://dx.doi.org/10.5772/54215

195

Speed range 1000 to 2500 rpm (2750rpm overspeed cut-out)

Emissions measurement was carried out using an EMS Exhaust Gas Analyzer (EMS 5002- W&800) that works on the EMS exhaust gas analyzer system software and the Driveability and Emissions Calculation Software (DECS). At the commencement of engine performance analy‐ sis described in section 2.7, the Exhaust Gas Analyzer was powered, allowed to warm-up for 10 minutes, and to zero (setting all the gases to zero). The sample hose was then connected, with the probe placed in the tail (exhaust) pipe. Readings were taken at intervals of 250 rpm of en‐ gine speed after conditions had stabilised at each speed. The technology of this analyzer allows for auto calibration before every analysis and a high degree of accuracy in the analysis of low concentrations of gases found in the engine. The DECS software was used for calculating and analysing other emissions related engine performance characteristics. For purposes of repeata‐

bility, the emission analyser accuracy and measuring range are shown in Table 3.

**Parameter Accuracy Range**

Carbon monoxide (CO) 0.06% 0 – 10% Carbon dioxide (CO2) 0.30% 0 – 20% Oxygen (O2) 0.10% 0 – 25% Nitrogen oxides (NOX) 1.00 ppm 0 – 5 000ppm

**Table 3.** Emissions analyser accuracy and measuring range.

Hydrocarbons (HC) 4.00 ppm 0 – 24 000 ppm

**Figure 3.** Schematic diagram of the experimental setup.

To establish that engine operating conditions were reproduced consistently as any deviation could exert an overriding influence on performance and emissions results, the reproducibili‐ ty of the dynamometer speed control set points were maintained within ± 0.067 Hz of the desired engine speed. Prior to the data recording, the compression ratio was set to the de‐ sired level and the engine speed was set to a maximum of 2500 revs/minute at full throttle. The engine was allowed to run on petroleum diesel fuel under steady state operating condi‐ tions, as opposed to transient conditions characterised by the stop-go type of pattern, for ap‐ proximately 30 minutes to reach fully warm conditions. This ensures best engine efficiency and effective burning of effects of the warm up cycle and to clear out any moisture from the system and exhaust. This also established the engine's operating parameters which consti‐ tute the baseline that was compared with the subsequent case when the birrea biodiesel was used. After the engine operating temperature had stabilised, the first sets of readings for brake power, engine torque and specific fuel consumption at the maximum speed of 2500 revs/min were recorded. The dynamometer load was then increased by adjusting the load current control mechanism until the engine speed reduced by steps of 250 revs/min to a minimum value of 1000 rpm. For each step, the data for brake power, engine torque and specific fuel consumption were automatically captured onto a PC using the data acquisition software provided by the engine manufacturer. All measurements were repeated three times for each test setting, while the test sequences were repeated three times.


Legend. BTDC: Before Top Dead Centre; ATDC: After Top Dead Centre. Source: [31]

**Table 2.** Engine Specifications

design feature which allows the compression ratio to be varied from 5:1 to 18:1. The lay‐ out of the experimental setup is shown in Fig. 3, while engine specifications are present‐

Engine

To establish that engine operating conditions were reproduced consistently as any deviation could exert an overriding influence on performance and emissions results, the reproducibili‐ ty of the dynamometer speed control set points were maintained within ± 0.067 Hz of the desired engine speed. Prior to the data recording, the compression ratio was set to the de‐ sired level and the engine speed was set to a maximum of 2500 revs/minute at full throttle. The engine was allowed to run on petroleum diesel fuel under steady state operating condi‐ tions, as opposed to transient conditions characterised by the stop-go type of pattern, for ap‐ proximately 30 minutes to reach fully warm conditions. This ensures best engine efficiency and effective burning of effects of the warm up cycle and to clear out any moisture from the system and exhaust. This also established the engine's operating parameters which consti‐ tute the baseline that was compared with the subsequent case when the birrea biodiesel was used. After the engine operating temperature had stabilised, the first sets of readings for brake power, engine torque and specific fuel consumption at the maximum speed of 2500 revs/min were recorded. The dynamometer load was then increased by adjusting the load current control mechanism until the engine speed reduced by steps of 250 revs/min to a minimum value of 1000 rpm. For each step, the data for brake power, engine torque and specific fuel consumption were automatically captured onto a PC using the data acquisition software provided by the engine manufacturer. All measurements were repeated three

times for each test setting, while the test sequences were repeated three times.

Diesel Tank

Petrol Tank

Air Filter

ed in Table 2.

ECU Dynamometer

**Figure 3.** Schematic diagram of the experimental setup.

Cooling Tower Water In

194 Advances in Internal Combustion Engines and Fuel Technologies

Silencer

Engine Input Parameters

Water Out

Data Logger

Exhaust Gas Analyser

Exhaust gas

#### **3.8. Emissions measurement**

Emissions measurement was carried out using an EMS Exhaust Gas Analyzer (EMS 5002- W&800) that works on the EMS exhaust gas analyzer system software and the Driveability and Emissions Calculation Software (DECS). At the commencement of engine performance analy‐ sis described in section 2.7, the Exhaust Gas Analyzer was powered, allowed to warm-up for 10 minutes, and to zero (setting all the gases to zero). The sample hose was then connected, with the probe placed in the tail (exhaust) pipe. Readings were taken at intervals of 250 rpm of en‐ gine speed after conditions had stabilised at each speed. The technology of this analyzer allows for auto calibration before every analysis and a high degree of accuracy in the analysis of low concentrations of gases found in the engine. The DECS software was used for calculating and analysing other emissions related engine performance characteristics. For purposes of repeata‐ bility, the emission analyser accuracy and measuring range are shown in Table 3.


**Table 3.** Emissions analyser accuracy and measuring range.
