Introduction
Tab.1 A summary of the performance and emission characteristics of water in diesel emulsion fuels |
Researcher’s Name | Engine type and operating conditions | Characteristics of fuel composition | Surfactant Type | HLB value | Torque | Brake power | BSFC | BTE | CO | HC | CO2 | NOx |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Basha et al. [10] | One cylinder, Engine speed=1500 r/min, Engine load= 100 % | Water= 15% (vol), Surfactant= 2% (vol) | Tween 80 and Span 80 | 8 | No information | No information | increase | increase | increase | increase | No information | decrease |
Seifi et al. [1] | Six cylinders, Engine speed= 1400–1900 r/min, Engine load= 25%–100% | Water= 2%–10% (vol), Surfactant= 2% (vol) | Span 80 | 4.3 | decrease | decrease | No information | No information | No information | No information | No information | No information |
Bidita et al. [8] | Engine speed= 2600 r/min, Engine load= 50% | Water= 0.7%–1% (vol), Surfactant= 0.25%–0.4% (vol) | Triton X-100 | - | No information | No information | No information | No information | increase | No information | decrease | decrease |
Alahmer et al.[4] | Four cylinders, Engine speed= 1000–3000 r/min, Engine load= 100% | Water= 5%–30%(vol), Surfactant= 2% (vol) | Tween 20 | 16.7 | decrease | decrease | increase | decrease | No information | No information | increase | decrease |
Basha et al. [25] | One cylinder, Engine speed= 1500 r/min, Engine load= 100% | Water= 5% (vol), Surfactant= 2% (vol) | Tween 80 and Span 80 | 8 | No information | No information | increase | increase | decrease | increase | No information | decrease |
Ithnin et al. [9] | One cylinder, Engine speed= 3000 r/min, Engine load= 25%–100% | Water=5%–20% (vol), Surfactant= 2% (vol) | Span 80 | 4.3 | No information | No information | No information | No information | increase | No information | No different | decrease |
Abu-Zaid [6] | One cylinder, Engine speed= 1200–3300 r/min, Engine load= 100% | Water= 5%–20% (vol), Surfactant= 2% (vol) | Tween 80 and Span 80 | - | increase | increase | decrease | increase | No information | No information | No information | No information |
Experimental
Material
Tab.2 Specifications of neat diesel fuel |
Properties | Value | Test type |
---|---|---|
Density at 15°C/(g·cm–3) | 0.827 | ASTM D 1298 |
Kinematic viscosity at 40°C/(mm2·s–1) | 2.83 | ASTM D 445 |
Cetane number | 56.34 | ASTM D 976 |
Net Calorific value/(MJ·kg–1) | 46.42 | ASTM D 4868 |
Flash point/°C | 67 | ASTM D 93 |
Cloud point/°C | 1 | ASTM D 97 |
Pour point/°C | –6 | ASTM D 2500 |
Water content/ppm | 54 | ASTM D 6304 |
Sulfur content/ppm | 48 | ASTM D 4294 |
Emulsion fuel preparation procedure
Engine test
Tab.3 Characteristics of applied diesel engine |
Type | Lombardini-Diesel 3LD510 |
---|---|
Number of cylinder | 1 |
Swept volume | 510 cm3 |
Bore | 85 mm |
Stroke | 90 mm |
Compression ratio | 17.5:1 |
Maximum torque at 1800 r/min | 32.8 N·m |
Maximum power at 3000 r/min | 9 kW |
Tab.4 Detailed properties of AVL DITEST GAS 1000 emission analyzer |
Variables | Measurement range | Measurement accuracy |
---|---|---|
CO | 0%–15% (vol) | 0.02% (vol) |
CO2 | 0%–20% (vol) | 0.3% (vol) |
HC | 0–30000 ppm (vol) | 4 ppm (vol) |
NO | 0–5000 ppm (vol) | 5 ppm (vol) |
Box-Behnken experimental design
Tab.5 Experimental ranges and factor levels of variables applied in the experimental design |
Independent parameters | Range and levels | ||
---|---|---|---|
–1 | 0 | + 1 | |
x1: Percentage of water/%(vol) | 5 | 7.5 | 10 |
x2: Percentage of surfactant/%(vol) | 0.5 | 1.25 | 2 |
x3: HLB value | 5 | 6.5 | 8 |
Tab.6 Experimental runs suggested by BBD |
Run | Coded values | Real variables | |||||
---|---|---|---|---|---|---|---|
x1 | x2 | x3 | Percentage of water/%(vol) | Percentage of surfactant/ %(vol) | HLB value | ||
1 | 0 | 0 | 0 | 7.5 | 1.25 | 6.5 | |
2 | +1 | +1 | 0 | 10 | 2 | 6.5 | |
3 | 0 | +1 | +1 | 7.5 | 2 | 8 | |
4 | –1 | +1 | 0 | 5 | 2 | 6.5 | |
5 | +1 | –1 | 0 | 10 | 0.5 | 6.5 | |
6 | –1 | 0 | +1 | 5 | 1.25 | 8 | |
7 | 0 | –1 | +1 | 7.5 | 0.5 | 8 | |
8 | 0 | 0 | 0 | 7.5 | 1.25 | 6.5 | |
9 | +1 | 0 | –1 | 10 | 1.25 | 5 | |
10 | 0 | 0 | 0 | 7.5 | 1.25 | 6.5 | |
11 | 0 | +1 | –1 | 7.5 | 2 | 5 | |
12 | 0 | –1 | –1 | 7.5 | 0.5 | 5 | |
13 | 0 | 0 | 0 | 7.5 | 1.25 | 6.5 | |
14 | –1 | –1 | 0 | 5 | 0.5 | 6.5 | |
15 | +1 | 0 | +1 | 10 | 1.25 | 8 | |
16 | –1 | 0 | –1 | 5 | 1.25 | 5 | |
17 | 0 | 0 | 0 | 7.5 | 1.25 | 6.5 |
Result and discussion
Emulsion stability analysis
Tab.7 Stability analysis of emulsion fuel |
Run | Real variable | Average droplet size/nm | PDI | Stability/h | ||
---|---|---|---|---|---|---|
x1 | x2 | x3 | ||||
1 (The BBD most repeated) | 7.5 | 1.25 | 6.5 | 503.4 | 0.413 | 168 |
4 (The highest stability) | 5 | 2 | 6.5 | 373.5 | 0.266 | 216 |
15 (The lowest stability) | 10 | 1.25 | 8 | 676.5 | 0.485 | 12 |
Tab.8 Reported values of emulsion fuel stability in various studies |
Reference | Emulsion fuel characteristic | Surfactant type | Emulsification time/ min | Stability duration |
---|---|---|---|---|
Hasannuddin et al. [45] | 20% water (vol) 1% surfactant (vol) | Span 80 | 5 | 75 min |
Bidita et al. [8] | 1% water (vol) 0.4% surfactant (vol) | Triton X-100 | 10 | 16 days |
Ghannam et al.[46] | 10% water (vol) 0.2% surfactant (vol) | Triton X-100 | 2 | 4 weeks |
Patil et al. [43] | 10% water (vol) 5% surfactant (vol) | Span 80 and tween 80 | 20 | 30 days |
Noor El-Din et al. [44] | 5% water (vol) 10% surfactant (vol) | Span 80 and tween 80 | 5 | 2 weeks |
Statistical analysis
Tab.9 Final correlations for variables of response in terms of real factors |
The response | Correlation |
---|---|
T | |
Pb | |
BSFC | |
BTE | |
CO | |
HC | |
CO2 | |
NOx |
Tab.10 BBDs with corresponding experimental and predicted responses for variables of response |
Run | Performance characteristics | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
T/(Nm) | Pb/kW | BSFC/(g·(kWh)–1) | BTE/% | ||||||||||
Exp. | Pre. | Exp. | Pre. | Exp. | Pre. | Exp. | Pre. | ||||||
1 | 19.85 | 19.85 | 3.78 | 3.78 | 391.61 | 391.80 436.82 | 24.43 | 24.41 | |||||
2 | 19.27 | 19.23 | 3.67 | 3.66 | 437.80 | 25.27 | 25.23 | ||||||
3 | 19.56 | 19.58 | 3.72 | 3.73 | 397.46 | 398.33 | 23.76 | 23.78 | |||||
4 | 19.86 | 19.85 | 3.79 | 3.78 | 386.60 | 388.47 | 22.65 | 22.60 | |||||
5 | 19.35 | 19.36 | 3.69 | 3.69 | 410.99 | 409.12 | 24.32 | 24.36 | |||||
6 | 19.89 | 19.88 | 3.79 | 3.79 | 374.69 | 371.96 | 22.60 | 22.63 | |||||
7 | 19.76 | 19.73 | 3.76 | 3.75 | 371.24 | 373.00 | 23.67 | 23.61 | |||||
8 | 19.88 | 19.85 | 3.79 | 3.78 | 392.84 | 391.80 | 24.40 | 24.41 | |||||
9 | 19.15 | 19.16 | 3.65 | 3.65 | 420.66 | 423.40 | 25.00 | 24.97 | |||||
10 | 19.86 | 19.85 | 3.78 | 3.78 | 389.83 | 391.80 | 24.46 | 24.41 | |||||
11 | 19.47 | 19.50 | 3.71 | 3.71 | 405.54 | 403.78 | 24.13 | 24.19 | |||||
12 | 19.65 | 19.63 | 3.74 | 3.74 | 387.07 | 386.20 | 23.33 | 23.32 | |||||
13 | 19.83 | 19.85 | 3.77 | 3.78 | 391.35 | 391.80 | 24.41 | 24.41 | |||||
14 | 19.95 | 20.00 | 3.80 | 3.81 | 372.28 | 373.26 | 22.40 | 22.44 | |||||
15 | 19.30 | 19.33 | 3.68 | 3.68 | 416.49 | 416.60 | 24.57 | 24.59 | |||||
16 | 19.90 | 19.87 | 3.78 | 3.78 | 383.92 | 383.81 | 22.40 | 22.37 | |||||
17 | 19.83 | 19.85 | 3.78 | 3.78 | 393.38 | 391.80 | 24.38 | 24.41 | |||||
Run | Emission characteristics | ||||||||||||
CO/% | HC/ppm | CO2/% | NOx/ppm | ||||||||||
Exp. | Pre. | Exp. | Pre. | Exp. | Pre. | Exp. | Pre. | ||||||
1 | 0.98 | 0.99 | 152 | 151.60 | 3.04 | 3.04 | 134 | 134.40 | |||||
2 | 1.10 | 1.08 | 203 | 203.37 | 3.35 | 3.36 | 108 | 106.25 | |||||
3 | 0.81 | 0.81 | 169 | 168.25 | 3.07 | 3.05 | 122 | 124.13 | |||||
4 | 0.77 | 0.79 | 150 | 151.37 | 3.02 | 3.03 | 129 | 127.50 | |||||
5 | 1.16 | 1.14 | 178 | 176.63 | 3.19 | 3.18 | 117 | 118.50 | |||||
6 | 0.79 | 0.78 | 148 | 147.37 | 2.95 | 2.96 | 137 | 136.38 | |||||
7 | 0.89 | 0.88 | 150 | 151.00 | 2.99 | 2.99 | 137 | 135.88 | |||||
8 | 1.02 | 0.99 | 151 | 151.60 | 3.04 | 3.04 | 135 | 134.40 | |||||
9 | 1.09 | 1.11 | 192 | 192.63 | 3.29 | 3.28 | 110 | 110.63 | |||||
10 | 0.99 | 0.99 | 153 | 151.60 | 3.08 | 3.04 | 133 | 134.40 | |||||
11 | 0.85 | 0.86 | 172 | 171.00 | 3.15 | 3.15 | 118 | 119.13 | |||||
12 | 0.83 | 0.83 | 151 | 151.75 | 2.89 | 2.91 | 136 | 133.88 | |||||
13 | 0.96 | 0.99 | 150 | 151.60 | 3.01 | 3.04 | 134 | 134.40 | |||||
14 | 0.75 | 0.77 | 142 | 141.62 | 2.93 | 2.92 | 140 | 141.75 | |||||
15 | 1.13 | 1.16 | 187 | 187.38 | 3.25 | 3.26 | 114 | 113.63 | |||||
16 | 0.85 | 0.83 | 146 | 145.62 | 2.98 | 2.97 | 132 | 132.38 | |||||
17 | 0.98 | 0.99 | 152 | 151.60 | 3.05 | 3.04 | 136 | 134.40 |
Tab.11 ANOVA results and statistical parameters of developed quadratic correlations |
Source | Performance characteristics models | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
T/(N·m) | Pb/kW | BSFC/(g·(kWh)–1) | BTE/% | |||||||||
F-value | P-value | F-value | P-value | F-value | P-value | F-value | P-value | |||||
Model | 80.85 | <0.0001 | 67.61 | <0.0001 | 100.86 | <0.0001 | 474.75 | <0.0001 | ||||
x1 | 529.63 | <0.0001 | 434.89 | <0.0001 | 632.59 | <0.0001 | 3353.16 | <0.0001 | ||||
x2 | 25.03 | 0.0016 | 23.00 | 0.0020 | 164.19 | <0.0001 | 174.44 | <0.0001 | ||||
x3 | 9.57 | 0.0175 | 9.22 | 0.0190 | 31.03 | 0.0008 | 2.58 | 0.1519 | ||||
x1x2 | 0.017 | 0.9013 | 0.035 | 0.8572 | 6.96 | 0.0336 | 40.30 | 0.0004 | ||||
x1x3 | 4.24 | 0.0786 | 1.40 | 0.2757 | 1.14 | 0.3208 | 32.78 | 0.0007 | ||||
x2x3 | 0.066 | 0.8044 | 0.000 | 1.0000 | 2.68 | 0.1458 | 40.63 | 0.0004 | ||||
x12 | 59.61 | 0.0001 | 48.06 | 0.0002 | 65.85 | <0.0001 | 239.18 | <0.0001 | ||||
x22 | 25.82 | 0.0014 | 19.74 | 0.0030 | 0.42 | 0.5357 | 154.41 | <0.0001 | ||||
x32 | 57.59 | 0.0001 | 58.29 | 0.0001 | 3.72 | 0.0951 | 169.86 | <0.0001 | ||||
Lack of fit | 6.50 | 0.0511 | 2.56 | 0.1929 | 5.47 | 0.0672 | 5.53 | 0.0659 | ||||
R2 | 0.9905 | 0.9886 | 0.9923 | 0.9984 | ||||||||
Adj. R2 | 0.9782 | 0.9740 | 0.9825 | 0.9863 | ||||||||
Pred. R2 | 0.8710 | 0.8743 | 0.8992 | 0.9784 | ||||||||
Adeq. precision | 27.968 | 25.514 | 35.719 | 66.991 | ||||||||
CVa/% | 0.2 | 0.21 | 0.6 | 0.23 | ||||||||
SDb | 0.039 | 8.03 | 2.37 | 0.056 | ||||||||
Source | Emission characteristics models | |||||||||||
CO/% | HC/ppm | CO2/% | NOx/ppm | |||||||||
F-value | P-value | F-value | P-value | F-value | P-value | F-value | P-value | |||||
Model | 39.81 | <0.0001 | 312.31 | <0.0001 | 44.72 | <0.0001 | 47.69 | <0.0001 | ||||
x1 | 283.91 | <0.0001 | 1969.63 | <0.0001 | 274.21 | <0.0001 | 243.62 | <0.0001 | ||||
x2 | 1.63 | 0.2425 | 346.68 | <0.0001 | 66.29 | <0.0001 | 86.39 | <0.0001 | ||||
x3 | 0.000 | 1.0000 | 3.19 | 0.1174 | 0.48 | 0.5124 | 6.03 | 0.0438 | ||||
x1x2 | 2.09 | 0.1919 | 37.60 | 0.0005 | 1.87 | 0.2142 | 0.25 | 0.6351 | ||||
x1x3 | 3.26 | 0.1140 | 6.38 | 0.0395 | 0.038 | 0.8508 | 0.062 | 0.8112 | ||||
x2x3 | 3.26 | 0.1140 | 0.52 | 0.4940 | 12.34 | 0.0098 | 0.55 | 0.4811 | ||||
x12 | 8.56 | 0.0221 | 326.16 | <0.0001 | 46.89 | 0.0002 | 65.48 | <0.0001 | ||||
x22 | 35.57 | 0.0006 | 43.39 | 0.0003 | 0.31 | 0.5925 | 9.02 | 0.0199 | ||||
x32 | 20.09 | 0.0029 | 43.39 | 0.0003 | 0.92 | 0.3685 | 10.61 | 0.0139 | ||||
Lack of fit | 20.09 | 0.2089 | 2.12 | 0.2410 | 1.10 | 0.4469 | 5.96 | 0.0587 | ||||
R2 | 0.9808 | 0.9975 | 0.9829 | 0.9840 | ||||||||
Adj. R2 | 0.9562 | 0.9943 | 0.9609 | 0.9633 | ||||||||
Pred. R2 | 0.7923 | 0.9741 | 0.8619 | 0.7856 | ||||||||
Adeq. precision | 18.006 | 58.083 | 22.964 | 22.959 | ||||||||
CVa/% | 2.95 | 0.86 | 0.83 | 1.58 | ||||||||
SDb | 0.028 | 1.39 | 0.026 | 2.02 |
Notes: a–CV=coefficient of variation; b–SD=standard deviation. |
Interaction between different operating parameters
Engine torque and brake power
BSFC
BTE
CO, HC, and CO2 emissions
NOx emissions
Optimization of engine performance and emission characteristics using RSM
Tab.12 Validation and repeatability test for engine performance and exhaust emission achieved under optimal conditions |
Optimum parameters | Value | Fixed parameters | Value | ||||
Water/% (vol) | 5 | Engine speed | 1800 r/min | ||||
Surfactant/% (vol) | 2 | Engine load | 100% | ||||
HLB | 6.8 | ||||||
Response parameters | Predicted | Experimental Run 1 | Experimental Run 2 | Experimental Run 3 | Average | Error /% | |
T/(N·m) | 19.84 | 19.86 | 19.82 | 19.80 | 19.83 | 0.07 | |
Pb/kW | 3.781 | 3.786 | 3.780 | 3.788 | 3.785 | 0.10 | |
BSFC/(g·(kWh)–1) | 387.42 | 386.60 | 390.06 | 390.22 | 388.96 | 0.40 | |
BTE/% | 22.57 | 22.64 | 22.44 | 22.43 | 22.50 | 0.30 | |
CO/% | 0.77 | 0.79 | 0.75 | 0.81 | 0.78 | 1.70 | |
HC/ppm | 152.06 | 150 | 149 | 159 | 153 | 0.40 | |
CO2/% | 3.02 | 3.05 | 2.94 | 2.97 | 2.99 | 1.12 | |
NOx/ppm | 128.63 | 124 | 132 | 133 | 130 | 0.80 |
Tab.13 Comparison of engine performance and exhaust emission for the best emulsion fuel and neat diesel fuel at an engine speed of 1800 r/min and full load |
Response parameters | Best emulsion fuel | Neat diesel fuel |
---|---|---|
T/(N·m) | 19.83 | 21.56 |
Pb/kW | 3.785 | 4.12 |
BSFC/(g·(kWh)–1) | 388.96 | 362.47 |
BTE/% | 22.50 | 21.39 |
CO/% | 0.78 | 0.69 |
HC/ppm | 153 | 166 |
CO2/% | 2.99 | 2.85 |
NOx/ppm | 130 | 159 |
Effect of engine load on engine performance and exhaust emission
Tab.14 Effect of engine load on engine performance and exhaust emission |
Fuel type/load/% | Engine performance | Exhaust emission | |||||||
---|---|---|---|---|---|---|---|---|---|
T/(N·m) | Pb/kW | BSFC/(g·(kWh)–1) | BTE/% | CO/% | HC/ppm | CO2/% | NOx/ppm | ||
Best emulsion fuel/100 | 19.83 | 3.785 | 388.96 | 22.50 | 0.78 | 153 | 2.99 | 130 | |
Neat diesel fuel/100 | 21.56 | 4.120 | 362.47 | 21.39 | 0.69 | 166 | 2.85 | 159 | |
Best emulsion fuel/50 | 9.76 | 1.860 | 511.56 | 17.11 | 0.10 | 63 | 2.31 | 154 | |
Neat diesel fuel/50 | 11.53 | 2.196 | 460.48 | 16.84 | 0.17 | 78 | 2.38 | 207 |