8.2.1 Preparation of Stable Fuel Blends
Preparation of biodiesel
In the present investigation, raw palm oil (RPO) having free fatty acid (FFA) content of 0.80% was procured from the local market of Kharagpur, India to produce biodiesel. As the raw oil had lesser FFA content, a base transesterification reac- tion was performed with the raw palm oil to produce biodiesel (B100). The process parameters for the reaction were 25% methanol/RPO (v/v), KOH (initial acid value (%) + 3.5) gram per liter of RPO, and 60 °C reaction temperature with a 30 min reaction process [12].
8.2.2 Preparation of Stable Water–Biodiesel Emulsion
After the production of biodiesel (B100), a biodiesel–diesel fuel blend (B20) was prepared by mixing 20% v/v of the B100 blend and 80% v/v of diesel. To produce a stable water-emulsified blend, two commercially available surfactants (i.e., Tween 80 and Span 80) were used as suggested by several past studies. In the present investi- gation, the water-emulsified biodiesel (WB20) was prepared with 1% v/v surfactants maintaining HLB value as 5 (0.93% v/v Span 80 + 0.7% v/v Tween 80), 10% v/v water and 89% v/v B20 blend using a homogenizer rotating at speed of 2500 rpm for 15 min. After the preparation, the prepared fuel sample was kept under observation to investigate any separation of the water layer and it was found that there was no
Fig. 8.1 Prepared fuel blends
water and creamy layer separation in the WB20 fuel sample up to 48 h. The prepared fuel blends, i.e., WB20, B20, B100, and diesel are shown in Fig. 8.1.
8.2.3 Measurement of Fuel Properties of Prepared Fuel Blend
Various fuel processing parameters such as air–fuel mixing, spray formation patterns, burning behavior, performance, and exhaust emissions characteristics are mainly depends on the fuel properties. Also, any developed or modified fuel should have undergone the measurement of fuel properties to ensure its adaptability. Hence, in the present investigation, various fuel properties such as calorific value, density, flash point, acid value, and kinematic viscosity were measured by following the latest ASTM standards.
8.2.4 Investigation of Combustion, Performance, and Exhaust Emission Characteristics
The experimental investigation of combustion, performance, and exhaust emissions was performed in a 10-kW single-cylinder, water-cooled, constant speed, DI diesel engine. For this reason, preliminary tests were performed in the engine. The test engine setup specifications are given in Table 8.1, and a schematic view of the experimental setup is shown in Fig. 8.2. The maximum engine brake power using diesel as a reference fuel was obtained at a load of 68 N −m and observed as 9.80 kW at 1400 ± 100 engine rpm. Therefore, the rated load or 100% load was taken as 68 N
− m and accordingly, the intermediate loads (25, 50, and 75%) were computed. Both the fuels (WB20 and diesel) were tested separately at different loads by operating the
Table 8.1 Engine
specifications Particulars Details
Engine Make Chetak, India
Model SDM-14
Number of cylinders 1
Bore × stroke (mm) 114.3 × 116
Stokes 4-stroke
Highest power (kW) 10 Engine rated speed (rpm) 1400 Compression ratio 17.5:1
Fuel injection time 24° before top dead center
engine for 2.5 h with each fuel. The various measurement instruments/sensors were installed on the engine test rig such as piezoelectric pressure transducer for pressure measurement, eddy current dynamometer for load application, rotary encoder for crank angle measurement, and proximity sensor for measuring the engine rpm etc.
The operational signals from these sensors were received and processed in the data acquisition system to find out ignition delay, brake power and brake-specific fuel consumption. Whereas an Indus flue gas analyzer was used to investigate the NOX
and hydrocarbon emissions at the exhaust tailpipe. Later on, these parameters were compared for both the fuels (i.e., test fuel (WB20) and ref. fuel (diesel).
Fig. 8.2 Schematic view of engine test setup. 1. Piezoelectric pressure transducer, 2. Proximity sensor, 3. Rotary encoder, 4. Exhaust gas analyzer, 5. Load indicator, 6. Engine rpm indicator, 7.
Exhaust pipe, 8. Brake power indicator
Table 8.2 Loading pattern
for 100-h test Load (% of rated load) Running time (min)
100 93.75 (11.72 min warm-up)
50 93.75
100 23.45
No-load 11.72
100 70.31
50 82
Total 375 min or 6.25 h
8.2.5 Investigation of Tribological Behavior of the Engine
Investigation of soot deposition formation
The assessment of soot deposition was performed by running the engine for a prolonged period of 100 h with each of the fuels (WB20 and Diesel). Initially, the engine was dismantled, and the engine components (piston top and cylinder head) were cleaned before the long run. The 100-h run was completed in 16 test cycles with 6.25 h each. The loading pattern for each test cycle was decided as per IS:
10000-Part: 9 [13] as given in Table 8.2. After the completion of the 100-h test with each fuel, the images of the piston top and cylinder head were captured for quality analysis. Similarly, deposited soot particles were carefully scraped using a wooden scraper from the engine components and weighed for quantitative assessment.
8.2.6 Lubrication Oil Defilement Analysis
The quality of lubrication oil was analyzed by obtaining the concentration of wear metal addition in the lubrication oil during and after the 100-h run with each fuel.
The higher concentration of heavy wear metal in lube oil could lead to increased viscosity of lubrication oil which further reduce the quality of lubrication and service life of lube oil. The lubrication oil sample was collected from the engine sump at 25-h intervals during the 100-h test. After completion of the long run with each test fuel, the lubricating oil was drained out and fresh lube oil was filled in the engine sump. The concentration of various heavy metals (i.e., Fe, Pb, Mn, Mg, and Zn) was obtained using atomic absorption spectroscopy (AAS) by performing the dry ash technique [10, 14]. The lube oil sample was collected in a 100-ml glass container and thoroughly mixed at 50 °C for 1 h using a water bath shaker. Approximately 10 g of mixed lube oil sample was then transferred to a dried silica crucible. The lube oil sample was then dried for 1 h at 120 °C using a hot plate. Thereafter, the sample was placed in a muffle furnace at a temperature of 450 and 650 °C for a time period of 4 and 2 h, respectively. The persisting ash in crucibles was then dissolved in 1.5 ml of
Table 8.3 Fuel properties of different test fuels used in the present investigation Fuel type Density (kg/
m3)
Viscosity (cSt)
Acid value (mg KOH/g)
Calorific value (MJ/kg)
Flash point (°C)
WB20 850 3.9 0.33 38.90 75
Diesel 824 2.55 0.13 42.63 58
IS 15607:2016 for biodiesel B100
860–900 3.5–5.0 <0.5 – > 101
IS 1460:2017 for diesel
820–860 2.0–5.0 <0.2 – < 66
ASTM methods
D 4052-22 D 446-12 D 5555-14 D 240-19 D 93–20
HCl. Thereafter, 100 ml of deionized water was added to the solution and subjected to metal detection using AAS.