Numerical study on emission characteristics of a diesel engine fuelled with diesel-spirulina microalgae-ethanol blends at various operating conditions

Fuel 262 (2020) 116519

Contents lists available at ScienceDirect

Fuel journal homepage: www.elsevier.com/locate/fuel

Full Length Article

Numerical study on emission characteristics of a diesel engine fuelled with diesel-spirulina microalgae-ethanol blends at various operating conditions

T

Upendra Rajaka, Prerana Nashineb, Tikendra Nath Vermaa,

⁎

a b

Department of Mechanical Engineering, National Institute of Technology Manipur, India Department of Mechanical Engineering, Manipur Technical University, Manipur, India

ARTICLE INFO

ABSTRACT

Keywords: Spirulina microalgae PM emission NOX emission Ethanol Ternary blend

The exhaust gas emissions from a compression ignition (CI) engines are mostly depend on the nature of fuel mixture, combustion chamber, and injection parameters. Higher combustion temperature, which leads to oxides of nitrogen (NOX) emission. In the present study, an engine of single-cylinder, direct cooling was operated at 1500 rpm speed with variable engine loads. Numerical simulation is performed using blends of diesel, spirulina microalgae biodiesel (BSP20, BSP40, and BSP100), and diesel-spirulina microalgae biodiesel – ethanol (DSP80E20). In this study, a variation in fuel injection timings (15.5° b TDC – 27.5° b TDC), nozzle diameters (0.15 mm − 0.4 mm), and swirl ratios (0.5–3.0) are investigated for emission characteristics (NOX, particulate matter, smoke and summary of emission). Results indicated that by increasing nozzle diameter (ND), injection timing (IT) and swirl ratio (SWR) the NOX emission is increased noticeably. Additionally, increasing ND, IT and SWR leads to higher particulate matter and summary of emissions for diesel and DSP80E20 but lower for BSP20 and BSP40 blends. The reduction in NOX emissions using DSP80E20, BSP20 and BSP40 blends as compared to diesel fuel. The results showed that at 0.25 mm (nozzle diameter) of spirulina microalgae, and ethanol-blended fuel showed better response. Smoke emission reduced with spirulina microalgae and ethanol due to the higher oxygen percentage within the blends. A significant decrease of particulate matter and summary of emission was also observed.

1. Introduction The use of alternative fuel in compression ignition engines is an attractive technique for decreasing engine emissions and dependency on petroleum-based fuel [1]. In specific, the biodiesel, ethanol and diesel blends has the possibility to be a substitute to petroleum base fuel for CI engines [2,3]. Biodiesel-ethanol-diesel blend is deducing fuel consumption and pollutant emission than that of the diesel fuel [4]. Also, addition of higher percentage of ethanol with biodiesel-diesel as ternary blends in the diesel engine shows a lesser promising approach for reduction of NOX emission [5], which is due to cooler combustion process with higher alcohol content. Biodiesel is manufactured as a form of 1st, 2nd and 3rd generation alternative fuel for compression ignition engines. However, alternative fuels improves the contents of oxygen for diesel-biodiesel-ethanol blends. Also, lubrication property is another advantage of alternative fuel that is beneficial for the engine. Same as ethanol, alternative fuel has a high possibility to decrease emissions, especially particulate emission [6]. Investigated engine characteristics fuelled with nine different

⁎

alternative fuels and diesel fuel on a direct injection, diesel engine with varying loads of engine. They found that the reduction in engine performance (thermal efficiency, cylinder pressure, torque, pressure rise rate). Another hand was obtained to be lower exhaust gas emission fuelled with alternative fuel than diesel [7]. Evaluated effects of blends (spirulina microalgae alternative fuel and diesel) on the diesel engine with varying loads of engine. The results showed that the dropped in engine efficiency to diesel. The showed decrease in emissions of HC, CO, and NOX emissions than the diesel at higher load [8]. Evaluated the effects of waste plastics oil blend with diesel fuel on the diesel engine characteristics at various injection timing (21.0°–25°.0 b TDC) and EGR (10, 20 and 30%). Experimental results indication of cylinder heat release rate and pressure are lower with dropped injection timing with all percentage of EGR. Thermal efficiency increased with increases injection timing and dropped with EGR percentage. The NOX emission increased with higher injection timing and reduced with increased EGR percentage in fuel and smoke emission improved with higher EGR and dropped with injection timing [9]. Evaluated experimentally compression of piston geometry (Re-entrant Toroidal,

Corresponding author. E-mail address: [email protected] (T. Nath Verma).

https://doi.org/10.1016/j.fuel.2019.116519 Received 26 September 2019; Received in revised form 20 October 2019; Accepted 25 October 2019 0016-2361/ © 2019 Elsevier Ltd. All rights reserved.

Fuel 262 (2020) 116519

U. Rajak, et al.

Nomenclature b TDC BSN CO CN CO2 DRS E100 HC High K Low

Medium 50% engine load ND Nozzle diameter Oxides of nitrogen NOX SE Summary of emission SWR Swirl ratio SPM Specific particulate matter BSP20 20% of spirulina and 80% of diesel fuel BSP40 40% of spirulina and 60% of diesel fuel BSP100 100% of spirulina D100 100% of diesel fuel DSP80E20 80% of BSP20 and 20% of ethanol EGR Exhaust gas recirculation FIT Fuel injection timing

Before top dead centre Bosch smoke number Carbon monoxide Cetane number Carbon dioxide Diesel-RK software 100% ethanol Hydrocarbon 100% engine load Kelvin 25% engine load

Toroidal, Straight Sided, and Hemispherical) on the engine fuelled with biodiesel and diesel fuel at various engine operating condition (fuel pressure, injection timing, engine brake power, engine compression ratio and nozzle holes). They found to be optimal piston geometry of Re-entrant Toroidal with improved engine efficiency. The increased engine efficiency and reduced fuel consumption with piston geometry of Re-entrant as compared to other piston geometry [10]. Reported effects of diesel engine characteristics fuelled with 10% carbon black biodiesel-3% water − 2% surfactant − 85% diesel blend (CBWD10). The results showed a higher heat release rate for CBWD10 blend compared to diesel and reduced NO emission about 16–42% but smoke emissions higher to diesel fuel [11]. In this investigation, the impact of 19, 21, and 23 MPa fuel injection pressures on the diesel engine using of the propanol (15%) – diesel (85%) blend investigated. They reported that improved ignition delay period with increased pressure of injection. The combustion duration lower for mixture fuel to diesel fuel and lower pressure of injection. However, an important fall in NOX and smoke emissions with propanol used in the blend [12]. Observed the impacts of Mahua (20%) with diesel (80%) on diesel engine characteristics. They reported that improved air-fuel mixing, atomization, and vaporization with small nozzle diameter using B20 blend. It was obtained better engine performance fuelled with B20 blend while NOX increased [13]. Investigated the effects of ethanoldiesel blends on diesel engine physiognomies fuelled with ethanoldiesel blends as a fuel. They found to be lower pressure and rise of pressure rate with ethanol-diesel blend than the diesel. The NOX emission reduced and soot emission increased with the lesser number of nozzles [14]. Evaluated the effects of edible, non-edible, waste oil, waste fats, alcohols and diesel on the engine characteristics with four engine loads and the results predicted that lower ignition delay for alternative fuel and combustion duration increased [15]. Investigated the effects of spirulina microalgae biodiesel and engine speeds using diesel engine. They obtained to be improved engine efficiency and reduction in energy consumption rate with speed increased. Additional, NOX emission reduced with increased engine speeds [16]. Reported effects of jojoba methyl ester blends (5%, 10%, and 20%) with diesel fuel using diesel engine variation in compression ratio (CR). They found to be higher cylinder pressure with increases CR (18–23). Improved NOX, CO and hydrocarbon (HC) emissions with increased compression ratios of engine. The cylinder pressure was reduced by using jojoba methyl ester fuel [17]. Experimentally investigated the effects of straight vegetable oil-diethyl ether – diesel blend (25% straight vegetable oil-10% diethyl ether-65% diesel) with variation in engine load, speed and compression ratio. They reported results showed that CO by 12.8%, NOX by 4.19%, and HC by 9.61% emissions could be reduced with 5% EGR [18]. Evaluated effects of swirl ratio and number of holes in injector on engine. The results indicated that the reduction in PM, and CO emissions but higher of NOX emission with increasing intensity of swirl ratio and injector holes [19]. Therefore, the NO and soot emissions would be

improved with a higher swirl intensity in the engine [20]. The results obtained to be the higher velocity of fluid, air-fuel mixing rate, and lower NOX emission when fuel temperature increased [21]. The present study arises from the various previous studies which showed that less studies have been carried out using spirulina microalgae biodiesel and ethanol as an alternative fuel for the diesel engine. The effects of variation in injection timing, nozzle diameter, and swirl ratio the use of spirulina microalgae biodiesel and ethanol almost cannot be found at the same time. Additional it is also noticed that the use of ternary blends of diesel-spirulina microalgae-ethanol biodiesel has not been reported. This investigation concentrates on the effects of variation in injection timing, nozzle diameter, and swirl ratio with 20, 40 and 100% spirulina microalgae addition with diesel and 20% ethanol addition with spirulina microalgae biodiesel-diesel fuel. The results are compared with diesel. 2. Material and methods 2.1. Fuel properties The present study, spirulina microalgae, ethanol, and diesel fuel were used for the investigation. 1st step, spirulina microalgae biodiesel was blended with diesel fuel at two different percentage (20% and 40% at volume-based respectively) represented as BSP20 and BSP40. 2nd step, ethanol was blended with BSP20, in which the volume basis of ethanol was varied by 20% (described as DSP80E20), as shown in Fig. 1. Viscosity is the most significant issue affecting the combustion process and engine characteristics [46–47]. Hence, an Eq. (1) was used to measure the density (ρ) of blends, Eq. (2) was used to calculate viscosity (υ) at 40 °C of blends. The Eq. (3) was used to measure the cetane number of combinations, Eq. (4) was used to calculate the heat value of blended fuel. The surface tension (σ) was calculated using the equation (6) were given in the literature [3,5–6,8,22,39,43–44]. All the fuel properties are taken from previous research. The fuel properties and their blends are shown in Table 1 (Table 2).

Fig. 1. Preparation of blends and ternary blend. 2

Fuel 262 (2020) 116519

U. Rajak, et al.

Table 1 Physical properties of test fuels. Fuel properties

D100

BSP100

E100

SPB20

SPB40

DSP80E20

LHV (MJ/kg) Viscosity at 40 °C (mm2/s) Density at 40 °C (kg/m3) CN Flash point Surface tension (N/m) Carbon (%) Hydrogen (%) Oxygen (%)

43.1 3.8

41.36 5.66

26.78 1.2

42.74 4.11

42.39 4.45

39.48 3.21

838

860

786–789

842.49

846.93

831.57

48–52 78 0.0262

52 > 128 0.0426

6 15 0.0243

48.81 88 0.0417

49.62 98 0.04199

40.07 73.4 0.0412

87.0 12.6 0.4

77.46 12.21 10.33

52.2 13.0 34.8

84.9 12.51 2.48

83.04 12.4 4.47

– – –

=

Xi

=

i

Xi ln

(6)

3

Compression ignition engine combustion process is simulated by Diesel-RK Software (DRS) and DRS is based on the multi-zone model. According to the previous literatures [22–28,41–42], Zeldovich mechanism was used to calculating the formation of NOX emission. The DRS follows the governing equations shown in Eqs. (7–24), taken into considering for this investigation and described by Assanis and Fiveland. Fig. 2 shows characteristics of diesel spray zones and vaporization is shown in Fig. 3 (Table 3).

(1)

2.3. Tool validation i

(2)

i=1

In the present study, direct injection, diesel engine with rated power of 3.7 kW and Bowl Piston Design Geometry was used. The experimental setup consists of a dynamometer (Power Mag) for the applied load. The engine is also connected to a crank angle encoder (Kubler) for calculating the crankshaft position and speed. A pressure transducer of piezoelectric (Kistler with air cooling) was used to calculate combustion

3

CNb =

14.92) × 10

(5)

0.8

2.2. Description of the numerical model

3 b

(4)

e (VBIb 10.975) 14.534

= (49.6

i=1

ln

=e

b

3 b

3 X HVi i=1 i i 3 X i=1 i i

HVb =

Xi CNi

(3)

i=1

Table 2 Diesel-RK software equations. Eqs. No

Name of equation

Governing equation for Diesel-RK model

Constants

7

Conservation of mass Conservation of species

dm dt

m (total mass in kg)

8 9

Species equations

10

Net generation rate of the ith species Species conservation equation Conservation of energy

11 12 13 14

Air/fuel mixture equivalence ratio Frictional mean effective pressure Specific fuel consumption

15

Heat Release during ignition delay

16

Heat release rate during premixed combustion Heat release rate during controlled combustion heat release rate during late combustion Zeldovich mechanism NO concentration during the combustion

17 18 19

20 21

NO concentration in a cylinder Specific NO emission

22

Soot formation

23 24

Hartridge smoke level Bosch smoke number

=

j mj

m Yi = i m d(mYi) = dt

j

mi = Mass of the ith species (kg/s)

Sg =

i Wmw

Yi =

j

mj m

sg = net generation rate of the ith species (kg/s)

mjYij + Sg

FMEP =

SFC=

i Wmw

(Yij Y cyl i )+

dQ d(mu) d = p + ht + dt dt dt (ma / mf ) (A / F) 1 = (A / F) = (m / m ) s a f s

v = specific volume (kg/m3) Wmw = Weight (kg/mol.) ρ = density (kg/m3)

j

P = pressure (MPa)

mjhj

ma = air mass flow (Kg/s) = = = constants, Pmax = maximum cylinder pressure, Vp = piston velocity (m/s) mf = fuel mass flow rate (kg/s), Pb = brake power (kW)

+ Pmax + Vp

mf Pb

= 3.8 × 10

6 (1

1.6 × 10 4 . n)

dx d

=

0

× (A 0 (mf /vi) × (

dx d

=

1

×

dx d

=

O2 d [NO] d

( )+ d u d

3 A3KT (1

x)(

2O , N2 + O

=

2

ud

T p

exp

(

Ea 8.312T

x 0) × (0 .1 ×

× (A2 (mf /vc) × (

u

70 CN + 25

ud + x 0))

x) × (

+

)

1

x))

NO + O ,N + O2

( ) d u d

dx/dτ = Heat release rate (1/s.),

NO + O

38020 T b [N2 ]e . [O]e . {1 ([NO] / [NO]e )2} 1 . 2365 2365 [NO] R . Tb . 1 + . e Tb . Tb [NO] e

P × 2.333 × 10 7 . e

= Angular velocity (rpm) R = Constant

rNOc = rNO r bc eNO =

( )

30 × rNO × Mbg LC × M

qc = Cycle fuel mass (kg) V = Current volume (cc) dx/dt = Heat release rate (J/deg.)

q dx d[C] =0.004 c dt K V dt

Hartridge = 100{1

(

[PM]=ZPM565 ln

u

= Fraction of fuel evaporated

KT = Evaporation constant, Q0 = Q1 = Q2 = Q3= Constants

x)

b

×

Ea = Activation energy for auto ignition process, n = Engine speed (rpm), P = Pressure (bar), T = Temperature (K) and τ = Time in second, CN = Cetane number x 0 = Fraction of burnt fuel during ignition delay

0.9545 exp( 2.4226[C ])}

Zpm = constant

)

1.206 10 10 BN

3

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 2. Spray zones [26–28].

Fig. 3. Vaporization of spray [26–28]. Table 3 Models used in simulation [25–28].

Table 5 Uncertainties of the direct injection setup.

Parameters

Model

Instrument

Uncertainty (%)

Ignition Delay Nitrogen oxides PM Smoke Soot Combustion

Tolstov’s Mechanism Zeldovich Mechanism Alkidas Mechanism Bosch and Hartridge Razleytsev Mechanism Multi-Zone model

Encoder Dynamometer Fuel burette Indicator of load Manometer sensor of pressure Smoke meter Sensor of speed Sensor of temperature Air flow Flue gas analyser

± 0.2 ± 0.15 ± 1.0 ± 0.2 ± 1.0 ± 0.5 ± 1.0 ± 1.0 ± 0.15 ± 0.5 CO2 ( ± 1.0) NOX ( ± 0.5) CO ( ± 1.0) HC ( ± 1.0) O2 ( ± 1.0)

Table 4 Details of engine and input parameters. Parameter

Value

Type Stroke Engine Bore Connecting rod Injection timing Compression ratio Speed Nozzle diameter Number of holes Swirl ratio

Single cylinder 110, mm naturally aspirated 80, mm 235, mm 15.5–27.5° b TDC 18.5 1500 rpm 0.15–0.40 mm 3 0.5–3.0

be ± 2.979. Diesel-RK software (DRS) was used for prediction of combustion behaviour and Zeldovich model was applied to calculate the NOX emission. Fig. 5 (a, and b) shows the cylinder pressure and heat release rate curves with crank angle for 100% diesel at high load. Fig. 5 (c) compares the NOX emission with engine load. The injection timing of fuel (23.5° b TDC), injection temperature of fuel (400 K), injection pressure of fuel (higher of 220 bar), engine speed (1500 rpm), and nozzle diameter (0.25 mm) for the numerical and experimental results are compared for diesel. From the figure of in-cylinder pressure, heat release rate and NOX emission Fig. 5 (a, b and c), the numerical results prediction with experiment data for tool validation. As a significance, the maximum deviation between the DRS tool results and experimental results was found to be 3.58% (89.76 bar for experimental, 93.1 bar for the numerical tool) for 100% diesel fuel at 100% load. The heat release rate and NOX emission error deviation were obtained to be 4.75% and 3.52% at 100% engine load, respectively.

pressure. The specifications of the engine are shown in Table 4. A Testo350 flue gas analyser is used measure the exhaust gases by the diesel engine, and uncertainty of measuring instruments are given in Table 5. The experimental setup of the diesel engine, as shown in Fig. 4. The conducted numerical simulation on a single cylinder, four stroke diesel engine fuelled with BSP20, BSP40, and ternary blend at low (25%), medium (50%) and high (100%) engine loads with various operating conditions. The uncertainty analysis was conducted based on the parameters such as uncertainties of the instruments are provided in Table 5. The total uncertainties within the experiments were found to 4

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 4. Experimental setup for tool validation.

Fig. 5. Simulated results against experimental result for a) cylinder pressure, b) cylinder heat release rate, and c) NOX emission. 5

Fuel 262 (2020) 116519

U. Rajak, et al.

NOX emission (ppm)

5000

D100

BSP20

BSP40

BSP100

6000

DSP80E20

5000

(a) Injection timing = 15.5 NOX emission (ppm)

6000

4000

3000

2000

1000

0

D100

BSP20

Low

Medium

4000

3000

2000

0

High

Low

Medium

D100

BSP20

BSP40

BSP100

6000

DSP80E20

(c) Injection timing = 19.5

5000

3000

2000

1000

D100

BSP20

DSP80E20

4000

3000

2000

0

Low

Medium

Low

High

Medium

D100

BSP20

BSP40

High

Engine load BSP100

6000

DSP80E20

D100 5000

NOX emission (ppm)

(e) Injection timing = 23.5

4000

3000

2000

1000

0

BSP100

1000

BSP20

BSP40

BSP100

DSP80E20

(f) Injection timing = 25.5

4000

3000

2000

1000

Low

Medium

0

High

Low

Medium

Engine load 6000

5000

NOX emission (ppm)

NOX emission (ppm)

5000

BSP40

(d) Injection timing = 21.5

Engine load 6000

High

Engine load

4000

0

DSP80E20

1000

NOX emission (ppm)

NOX emission (ppm)

5000

BSP100

(b) Injection timing = 17.5

Engine load 6000

BSP40

Engine load D100

BSP20

BSP40

BSP100

DSP80E20

(g) Injection timing = 27.5

4000

3000

2000

1000

0

Low

Medium

High

Engine load

Fig. 6. Injection timing effect on the NOX emission at a) low, b) medium and c) high load.

6

High

Fuel 262 (2020) 116519

U. Rajak, et al.

NOX emission (ppm)

5000

D100

BSP20

BSP40

BSP100

6000

DSP80E20

(a) Nozzle diameter = 0.15 mm

5000

NOX emission (ppm)

6000

4000

3000

2000

1000

Low

Medium

BSP20

BSP40

2000

Low

Medium

(c) Nozzle diameter = 0.25 mm

1000

BSP20

BSP40

BSP100

DSP80E20

(d) Nozzle diameter = 0.35 mm

4000

3000

2000

1000

0

Low

Medium

0

High

Low

Medium

Engine load D100

BSP20

BSP40

High

Engine load BSP100

6000

DSP80E20

5000

(d) Nozzle diameter = 0.3 mm NOX emission (ppm)

NOX emission (ppm)

High

Engine load D100

5000

2000

4000

3000

2000

D100

BSP20

BSP40

BSP100

DSP80E20

(f) Nozzle diameter = 0.4 mm

4000

3000

2000

1000

1000

0

DSP80E20

3000

DSP80E20

3000

5000

BSP100

(b) Nozzle diameter = 0.2 mm

6000

BSP100

NOX emission (ppm)

NOX emission (ppm)

D100

4000

6000

BSP40

4000

0

High

Engine load

5000

BSP20

1000

0

6000

D100

0

Low

Medium

High

Low

Medium

High

Engine load

Engine load

Fig. 7. Nozzle diameter effect on the NOX emission at a) low, b) medium and c) high load.

3. Results and discussion

emissions in diesel engines is mostly due to the Zeldovich mechanism at the high flame temperatures, particularly at partly and high loads due to prompt NOX formation throughout the droplet red-hot. Fig. 6 (a) shows the variation of NOX at 15.5° b TDC fuel injection timing (FIT). The results showed that the lowest NOX emission is 1069 ppm for BSP40 at high engine loads. In Fig. 6 (b) shows the variation of NOX at 17.5° b TDC fuel injection timing and predicted the lowest amount of NOX emission of BSP40 and highest for D100 and BSP100 at all engine loads. Also, the value of NOX emissions was found to be similar for 21.5, 23.5, 25.5, and 27.5° (before top dead center) fuel injection timing at the all

3.1. Effects of injection timing, nozzle diameter and swirl ratio on the NOX emission The exhaust NOX emission for diesel engine were calculated by the numerical method. Fig. 6 shows the NOX emission at different engine loads with different fuel injection timing for diesel, spirulina microalgae biodiesel and its blends (BSP20, BSP40), and diesel-spirulina microalgae-ethanol combination (DBSP80E20). Generation of NOX 7

Fuel 262 (2020) 116519

U. Rajak, et al.

NOX emission (ppm)

5000

D100

BSP20

BSP40

BSP100

6000

DSP80E20

(a) Swirl ratio = 0.5

4000

3000

2000

1000

0

D100

BSP20

Low

3000

2000

Medium

0

High

Low

Medium

BSP40

BSP100

DSP80E20 5000

(c) Swirl ratio = 1.5 NOX emission (ppm)

NOX emission (ppm)

BSP20

4000

3000

2000

1000

D100

BSP20

DSP80E20

4000

3000

2000

Low

Medium

0

High

Low

Medium

D100

BSP20

BSP40

High

Engine load BSP100

DSP80E20

6000

D100

(e) Swirl ratio = 2.5 5000

NOX emission (ppm)

NOX emission (ppm)

BSP100

1000

4000

3000

2000

1000

0

BSP40

(d) Swirl ratio = 1.5

Engine load

5000

High

Engine load 6000

D100

6000

DSP80E20

1000

6000

0

BSP100

4000

Engine load

5000

BSP40

(b) Swirl ratio = 1.0

5000

NOX emission (ppm)

6000

BSP20

BSP40

BSP100

DSP80E20

(f) Swirl ratio = 3.0

4000

3000

2000

1000

Low

Medium

0

High

Engine load

Low

Medium

High

Engine load

Fig. 8. Swirl ratio effect on the NOX emission at a) low, b) medium and c) high load.

tested engine load. Therefore, the value of NOX emission can be increased by increasing the fuel injection timing. At 23.5° b TDC fuel injection timing, BSP40 shows the lowest NOX emission as compared to others tested blends. The increase of NOX emissions with the rise in engine load is due to higher combustion temperature and adiabatic flame temperature [29,30]. Variation of NOX emission for diesel, spirulina microalgae biodiesel and ethanol blends with different engine loads are presented in Fig. 7 for different nozzle diameters. The exhaust NOX emission depends on the temperature of combustion, oxygen, and the reaction time [30–32]. Lower calorific value and higher viscosity lead to lower NOX emission. The lesser temperature or improper use of air throughout combustion may also lead to lower NOX emission [33]. NOX emission of the engine

increases with an increase in engine loads. This is due to rise in the temperature within the engine cylinder with higher engine load [34–36]. The maximum NOX emission for D100, BSP20, BSP40, BSP100, and DBSP80E20 at high engine load are 3958.4, 3212.9, 2656.1, 4837.6, and 2782.1 ppm, respectively, as shown in the Fig. 7 (c). NOX emission of the engine increases with increase in nozzle diameter. An increase in temperature of combustion with higher engine load according to this study. Variation of NOX emission for diesel, spirulina microalgae biodiesel, and ethanol blends with different engine loads are presented in Fig. 8 for different swirl ratio. The maximum NOX emission for D100, BSP20, BSP40, BSP100, and DBSP80E20 are 315.6, 595.7, 581.5, 911.4, and 376 ppm for low load, 2000.8, 2322.3, 2194.9, 2336.4, and 829.35 ppm 8

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 9. Fuel injection timing effect on the smoke emission at a) low, b) medium and c) high load.

9

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 10. Nozzle diameter effect on the BSN emission at a) low, b) medium and c) high load.

10

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 11. Swirl ratio effect on the BSN emission at a) low, b) medium and c) high load.

11

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 12. Injection timing effect on the specific particulate matter emission at a) low, b) medium and c) high load.

12

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 13. Nozzle diameter effect on the specific particulate matter emission at a) low, b) medium and c) high load.

for medium load and 395, 3212.9, 2656.1, 4837.6, and 2782.1 ppm for high engine load at 1.5 swirl ratio, respectively, as shown in Fig. 8 (c). The NOX emissions of swirl ratio 3.0 is the highest (4081.8, 3371.3, 2878.2, 4910.7 and 2166.9 ppm for diesel, BSP20, BSP40, BSP100 and DBSP80E20), at 100% load, respectively. The NOX emissions of swirl ratio 0.5 is the lowest (3740.2, 2974.5, 2314.7, 4693.7 and 2633.9 ppm for diesel, BSP20, BSP40, BSP100 and DBSP80E20), at 100% load. NOX

emission of the engine increases with increase in swirl ratio. Higher engine load means higher combustion temperatures, which is effected by amount of injected fuel in cylinders. Combustion temperature and contents of oxygen plays a dynamic role in formation of NOX. Higher combustion temperatures and residence time of the gases at that temperatures result in higher NOX.

13

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 14. Swirl ratio effect on the specific particulate matter emission at a) low, b) medium and c) high load.

3.2. Effects of injection timing, nozzle diameter and swirl ratio on the Bosch smoke number (BSN)

be attributed to a deficiency of reduced atomization, excess fuel accumulation in the combustion chamber, and air in combustion rich zone [37,38,40]. Variation of the BSN emission for diesel, spirulina microalgae biodiesel, ethanol and its blends with fuel injection timing, nozzle diameter and swirl ratio are presented in Figs. 9–11. As the advanced fuel injection timing increase, the decreases the formation of smoke emission. The spirulina microalgae biodiesel blends at the all advanced fuel injection timing were obtained to be lower to diesel fuel, but higher for

The formation of smoke emission due to incomplete burning of the hydrocarbon, improper combustion, insufficient oxygen contents [11]. The formation of smoke emission depends on the combustion temperature and oxidation process, viscosity and flame velocity, and engine load [33]. The formation of smoke emission increases with the increase in the engine load. In CI engines, the formation of smoke emission can 14

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 15. Injection timing effect on the summary of emission at a) low, b) medium and c) high load.

15

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 16. Nozzle diameter effect on the summary of emission at a) low, b) medium and c) high load.

the ethanol addition to diesel-spirulina microalgae biodiesel blend. This may be due to the complete combustion process. Smoke emission maximum value for D100, BSP20, BSP40, BSP100, and DBSP80E20 are 0.45, 0.344, 0.283, 0.32, 0.267 BSN for low load, 0.63, 0.485, 0.42, 0.70, 1.1 BSN for medium load and 3.03, 2.89, 2.92, 2.3, 5.1 BSN for high engine load respectively, at 1.5 swirl ratio, 23.5° b TDC and 0.25 mm nozzle diameter, as shown in Fig. 11. The BSN value for the BSP20 by 46.2%, BSP40 by 3.63% and BSP100 by 24.0% was found to

be lower to diesel fuel (D100) at 23.5° before top dead center. The BSN value for 19.5° b TDC is the highest (5.12, 3.2, 3.1, 2.7 and 5.12 BSN for D100, BSP20, BSP40, BSP100 and DBSP80E20) and 27.5° b TDC is the lowest (2.86, 2.42, 2.47, 2.1, and 3.7 BSN for D100, BSP20, BSP40, BSP100 and DBSP80E20), at 100% load. This may be due to the fact that increasing the injection timing, lower the droplet size leading to better mixing rate and improved combustion. The BSN value for 0.1 mm (ND) is the highest (4.79, 4.11, 4.25, 2.53

16

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 17. Swirl ratio effect on the summary of emission at a) low, b) medium and c) high load.

and 3.12 BSN for D100, BSP20, BSP40, BSP100 and DBSP80E20) and 0.25 mm (ND) is the lowest (3.0, 2.89, 2.9, 2.3, and 2.67 BSN for D100, BSP20, BSP40, BSP100 and DBSP80E20), at 100% load. The BSN value for SWR1.0 is the highest (4.12, 2.97, 3.06, 2.3 and 5.19 BSN for D100, BSP20, BSP40, BSP100 and DBSP80E20) and SWR2.0 is the lowest (3.0, 2.85, 2.92, 2.3, and 5.01 BSN for D100, BSP20, BSP40, BSP100 and DBSP80E20), at 100% load. The spirulina microalgae biodiesel blends at the all nozzle diameter and swirl ratio were obtained to be lower to diesel fuel, but higher for the ethanol addition to diesel-spirulina microalgae biodiesel blend. Biodiesel has a higher oxygen contents and

lower carbon than decreases fuel consumption and reduced smoke emission [13,48]. 3.3. Effects of injection timing, nozzle diameter (ND) and swirl ratio (SWR) on the specific particulate matter (SPM) emission The variation of SPM emission versus engine loads with different fuel injection timing, nozzle diameter, and swirl ratio fuelled with BSP20, BSP40, BSP100, DBSP80E20 and diesel fuel are illustrated in Figs. 12–14. The SPM emissions of the diesel engine were calculated by 17

Fuel 262 (2020) 116519

U. Rajak, et al.

In Fig. 16 shows the variation of SE at nozzle diameter (0.15–0.4 mm), also predicted a better value of SE up to 0.3 mm (ND). The value of SE emission almost improved with increased in nozzle diameter. Therefore, the amount of SE increases with engine load all tested blends is due to increased SPM and NOX emission. At 21.5–23.5° b TDC, BSP20, and BSP40 shows a better summary of emission as compared to diesel and DBSP80E20. In Fig. 17, the summary of emission increases with an increase in engine loads and swirl ratio. This is due to the rise temperature of combustion at higher engine load [6]. The results obtained from the Diesel-RK simulation are compared with the diesel fuel values under same operating conditions of engine emissions for the different binary blends and ternary blend at low, medium and high engine loads is presented in the study. The summary of emissions was described in Table 6 with the operating condition using the blended fuel and diesel fuel. The numerical results show that by an increase in engine load a higher NOX, SPM and smoke emissions has been investigated by the DRS. The results reveal that spirulina microalgae biodiesel has a significant effect on NOX, SPM, and smoke emissions. Addition ethanol to diesel-spirulina microalgae blend is having a considerable impact on NOX emissions. The variation of allocation of fuel zones and heat release rate at full condition for tested fuel blends in the present study with 23.5 b TDC (FIT), 0.25 mm (ND) and SWR1.5, as shown in Fig. 18. The Fuel spray formation and combustion simulation of the designed piston bowl geometries are shown in Fig. 18. From the Diesel-RK simulation software results, BSP20 the mixture is found to be effective emissions parameters with others blends. The test results of combustion characteristics are given with 23.5° b TDC (FIT), 0.25 mm (ND) and SWR1.5 for 357.1° crank angle.

Table 6 Summary of emissions at high engine load. Input parameters

Conditions

NOX

SPM

BSN

SE

Engine load Blends (BSP20 and BSP40) Blend (DSP80E20) Injection timing (15.5°–27.5° b TDC) Nozzle diameter (0.15–0.4 mm) Swirl ratio (up to 2.0)

↑

↑ ↓ ↓ ↑ ↑ ↑

↑ ↓ ↑ ↑ ↑ ↑

↑ ↓ ↑ ↑ ↑ ↓

↑ ↓ ↑ ↑ ↑ ↑

↑ ↑ ↑

↑Increase, ↓Decrease.

the numerical method. Generation of SPM emissions in diesel engines is calculating to the Alkidas Mechanism in this study. Fig. 12 shows the variation of SPM emission at 15.5–27.5° b TDC fuel injection timing and shows that the lowest SPM emission at 27.5° is 0.49 g/kWh for BSP100 at high engine loads. The highest value of SPM emission at 25.5° b TDC fuel injection timing is 1.99 g/kWh for DBSP80E20 at high engine loads. In Fig. 13 shows the variation of SPM at nozzle diameter (0.15–0.4 mm), also predicted better value of SPM emission for 0.25–0.3 mm (ND). The value of SPM emission reduced with increased nozzle diameter up to 0.3 mm (nozzle diameter). The lowest value of SPM emission at 0.25 mm (ND) is 0.522 g/kWh for BSP100 and highest is 1.92 g/kWh for DBSP80E20 with high engine loads. Also, the value of SPM emissions was found to be similar trend for 0.15 to 0.4 mm (ND), at the all tested engine load. Therefore, the value of SPM emission can be increased with addition ethanol to blends. At 23.5° b TDC, BSP20, BSP40 and BSP100 shows the lower SPM emission to diesel. The decreases of SPM emissions with the rise in engine load is due to higher combustion temperature, and adiabatic flame temperature. The exhaust SPM emission depends on the combustion temperature, oxygen contents, carbon chain length of the biodiesel and the time for the reaction. Higher oxygen contents lead to lower SPM emission [6,16,24,45]. The SPM emission reduced with increased SWR up to 2.0 and increases with increase in engine loads, as shown in Fig. 14. This is due to increase in the combustion temperature within the engine cylinder at higher engine load [6]. The maximum SPM emission for D100, BSP20, BSP40, BSP100, and DBSP80E20 at high engine load are 1.82, 1.4, 0.692, 0.552, and 1.55 g/kWh, respectively as shown in figure. The SPM emission of the engine decreases with increasing spirulina microalgae biodiesel in this ingestion. This is due to higher in the oxygen contend within the spirulina microalgae biodiesel and better combustion process within the engine cylinder. As it can be seen from the figure of SPM emission with engine loads, SPM emission increases with increase in engine load. Higher engine load means higher combustion temperatures, which is effected by amount of injected fuel in the cylinder. Combustion temperature and content of oxygen plays a dynamic role in formation of SPM emission.

4. Conclusion The effects of fuel injection timing, nozzle diameter, and swirl ratio on the exhaust emissions of a diesel engine is investigated using diesel, spirulina microalgae biodiesel and ethanol. The following conclusions are drawn in the present study.

• The NO emission increases with increasing advanced fuel injection timing, nozzle diameter and swirl ratio. • The NO for biodiesel blends (BSP20 and BSP40) and ternary blend (DSP80E20) are lower than that of the diesel fuel. At • the swirl ratio up to 1.5, better-operating conditions was observed. • When the test engine was fuelled with biodiesel and its blends X

X

• •

3.4. Effects of injection timing, nozzle diameter (ND) and swirl ratio (SWR) on the summary of emission (SE) Summary of emission (SE) of the diesel engine was calculated by the numerical method. Figs. 15–17 shows the variation of SE emissions for injection timing, nozzle diameter, and swirl ratio. The fuel using diesel (D100), BSP20, BSP40 and DBSP80E20 tested at engine loads. Generation of SE in diesel engines was masseur to particulate matter and NOX emission based. Fig. 15 shows the variation of SE at 15.5–27.5° b TDC fuel injection timing and shows that the lowest SE is BSP40 for all tested fuel injection timing at high engine loads. The highest value of SE for DBSP80E20 as compared to D100, BSP0 and BSP40 at high engine load.

• •

(BSP20 and BSP40), SPM emissions decreased. But increases when ethanol is added. The SPM emission increased with increasing engine load. At 0.25 mm ND, SWR1.5 and 23.5° b TDC, SPM emission are reduced by 9.7, 5.9 and 27.7% for BSP20, BSP40 and BSP100 respectively at high load. Smoke emission (BSN) was obtained to be lower for spirulina microalgae biodiesel and diesel blends (BSP20, BSP40, and BSP100). BSN increases with increasing fuel injection timing, nozzle diameter (up to 0.3 mm) and swirl ratio (up to 2.0). However, smoke emissions increase with ethanol addition to diesel and spirulina biodiesel blend. Emission are found to be better between 21.5° and 23.5° b TDC (fuel injection timing), 0.25 mm (nozzle diameter) and swirl ratio (up to 1.5). 40% spirulina microalgae biodiesel added was found to be optimum.

The overall test result indicates that the trade-off between NOX, SPM, and smoke emissions of diesel engine was reduced by using

18

Fuel 262 (2020) 116519

U. Rajak, et al.

Fig. 18. Variation of allocation of fuel zones and heat release rate at full condition for tested fuel blends in the present study with 23.5° b TDC (FIT), 0.25 mm (ND) and SWR1.5 for 357.1° crank angle.

spirulina microalgae biodiesel–diesel blends and BSP20 and BSP40, the optimum and most favourable blend ratio was found to be without any modifications in the engine.

influence the work reported in this paper. References [1] Rajak U, Verma TN. Effect of emission from ethylic biodiesel of edible and nonedible vegetable oil, animal fats, waste oil and alcohol in CI engine. Energy Convers Manage 2018;166:704–18. [2] Shahir SA, Masjuki HH, Kalam MA, Imran A, Fattah IMR, Sanjid A. Feasibility of diesel – biodiesel – ethanol / bioethanol blend as existing CI engine fuel: An

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to 19

Fuel 262 (2020) 116519

U. Rajak, et al.

[3] [4] [5] [6] [7] [8] [9]

[10] [11] [12] [13] [14] [15] [16] [17] [18]

[19] [20] [21] [22] [23] [24] [25]

assessment of properties, material compatibility, safety and combustion. Renew Sustain Energy Rev 2014;32:379–95. Ahmadi M, Shun C, Yung K. Study of combustion, performance and emissions of a diesel engine fueled with ternary fuel in blended and fumigation modes. Fuel 2019;235:288–300. Wu Q, Xie X, Wang Y, Roskilly T. Effect of carbon coated aluminum nanoparticles as additive to biodiesel- diesel blends on performance and emission characteristics of diesel engine. Appl Energy 2018;221:597–604. Shamun S, Belgiorno G, Di G, Beatrice C, Tunér M. Performance and emissions of diesel-biodiesel-ethanol blends in a light duty compression ignition engine. Appl Therm Eng 2018;145:444–52. Rajak U, Nashine P, Verma TN, Pugazhendhi A. Performance, combustion and emission analysis of microalgae Spirulina in a common rail direct injection diesel engine. Fuel 2019;255:115855. Rajak U, Nashine P, Subhaschandra T, Verma TN. Numerical investigation of performance, combustion and emission characteristics of various biofuels. Energy Convers Manage 2018;156:235–52. Rajak U, Nashine P, Verma NT. Assessment of diesel engine performance using spirulina microalgae biodiesel. Energy 2019;166:1025–36. Damodharan D, Sathiyagnanam AP, Rana D, Kumar BR, Saravanan S. Combined influence of injection timing and EGR on combustion, performance and emissions of DI diesel engine fueled with neat waste plastic oil. Energy Convers Manage 2018;2018(161):294–305. Channappagoudra M, Ramesh K, Manavendra G. Comparative study of standard engine and modified engine with different piston bowl geometries operated with B20 fuel blend. Renewable Energy 2019;133:216–32. Wamankar AK, Murugan S. DI diesel engine operated with Carbon-black-waterdiesel slurry at different injection timing and nozzle opening pressure. J Energy Inst 2016;89(4):731–44. Mehmet Ş. The effect of the injection pressure on single cylinder diesel engine fueled with propanol – diesel blend. Fuel 2019;254:115617. Kumar MV, Babu AV, Kumar PR. Experimental investigation on the effects of diesel and mahua biodiesel blended fuel in direct injection diesel engine modified by nozzle orifice diameters. Renewable Energy 2018;119:388–99. Dong S, Yang C, Ou B, Lu H, Cheng X. Experimental investigation on the effects of nozzle-hole number on combustion and emission characteristics of ethanol/diesel dual-fuel engine. Fuel 2018;217:1–10. Rajak U, Verma TN. A comparative analysis of engine characteristics from various biodiesels: Numerical study. Energy Convers Manage 2019;180:904–23. Rajak U, Verma TN. Spirulina microalgae biodiesel - A novel renewable alternative energy source for compression ignition engine. J Cleaner Prod 2018;201:343–57. Hawi M, Elwardany A, Ookawara S, Ahmed M. Effect of compression ratio on performance, combustion and emissions characteristics of compression ignition engine fueled with jojoba methyl ester. Renewable Energy 2019;141:632–45. Krishnamoorthi M, Malayalamurthi R, Sakthivel R. Optimization of compression ignition engine fueled with diesel - chaulmoogra oil - diethyl ether blend with engine parameters and exhaust gas recirculation. Renewable Energy 2019;134:579–602. Yoon S, Lee S, Kwon H, Lee J, Park S. Effects of the swirl ratio and injector hole number on the combustion and emission characteristics of a light duty diesel engine. Appl Therm Eng 2018;142:68–78. Wei S, Wang F, Leng X, Liu X, Ji K. Numerical analysis on the effect of swirl ratios on swirl chamber combustion system of DI diesel engines. Energy Convers Manage 2013;75:184–90. Khoshhal A, Rahimi M, Abdulaziz A. CFD study on influence of fuel temperature on NOX emission in a HiTAC furnace. Int Commun Heat Mass Transfer 2011;38:1421–7. Qi DH, Ding XQ, Zhao WB, Yang K. Spray characteristics and engine performance of vegetable oil – diesel – ethanol hybrid fuel. J Energy Eng 2019;145(4):04019011. Rajak U, Verma TN. Influence of combustion and emission characteristics on a compression ignition engine from a different generation of biodiesel. Eng Sci Technol Int J 2019. Rajak U, Nashine P, Verma TN. Performance analysis and exhaust emissions of Aegle methyl ester operated compression ignition engine. Thermal Sci Eng Progress 2019;12:100354. Datta A, Mandal BK. Engine performance, combustion and emission characteristics of a compression ignition engine operating on different biodiesel-alcohol blends.

Energy 2017;125:470–83. [26] Al-dawody MF, Bhatti SK. Optimization strategies to reduce the biodiesel NOX effect in diesel engine with experimental verification. Energy Convers Manage 2013;68:96–104. [27] Kuleshov A, Mahkamov K. Multi-zone diesel fuel spray combustion model for the simulation of a diesel engine running on biofuel. Proc Inst Mech Eng Part A J Power Energy 2018;222:309–21. [28] Kuleshov A, Kozlov A, Mahkamov K. Self-ignition delay prediction in PCCI direct injection diesel engines using multi-zone spray combustion model and detailed chemistry. SAE Technical Paper 2010. 2010–01-1960. [29] Shrivastava P, Verma TN, Pugazhendhi A. An experimental evaluation of engine performance and emisssion characteristics of CI engine operated with Roselle and Karanja biodiesel. Fuel 2019;254:115652. [30] Abed KA, Gad MS, Morsi AKEL, Sayed MM, Elyazeed SA. Effect of biodiesel fuels on diesel engine emissions. Egypt J Petrol 2019;28(2):83–188. [31] Raman LA, Deepanraj B, Rajakumar S, Sivasubramanian V. Experimental investigation on performance, combustion and emission analysis of a direct injection diesel engine fuelled with rapeseed oil biodiesel. Fuel 2019;246:69–74. [32] Sayin C, Gumus M, Canakci M. Influence of injector hole number on the performance and emissions of a DI diesel engine fueled with biodiesel e diesel fuel blends. Appl Therm Eng 2013;61(2):121–8. [33] Yaliwal VS, Banapurmath NR, Gireesh NM, Hosmath RS, Donateo T, Tewari PG. Effect of nozzle and combustion chamber geometry on the performance of a diesel engine operated on dual fuel mode using renewable fuels. Renewable Energy 2016;93:483–501. [34] Ashok B, Nanthagopal K, Saravanan B, Azad K, Patel D, Sudarshan B, et al. Study on isobutanol and Calophyllum inophyllum biodiesel as a partial replacement in CI engine applications. Fuel 2019;235:984–94. [35] Nanthagopal K, Ashok B, Saravanan B, Pathy MR, Sahil G, Ramesh A. Study on decanol and Calophyllum Inophyllum biodiesel as ternary blends in CI engine. Fuel 2019;239:862–73. [36] Nanthagopal K, Ashok B, Saravanan B, Mathew S, Chandra S. Effect of next generation higher alcohols and Calophyllum inophyllum methyl ester blends in diesel engine. J Cleaner Prod 2018;180:50–63. [37] Venu H, Raju VD, Subramani L. Combined effect of influence of nano additives, combustion chamber geometry and injection timing in a DI diesel engine fuelled with ternary (diesel-biodiesel-ethanol) blends. Energy 2019;174:386–406. [38] Rajak U, Nashine P, Verma TN. Experimental study on spray characteristics of biodiesel-diesel fuels blends in a constant volume chamber. J Eng Appl Sci 2018;5(2). ISSN: 1658 – 6638. [39] Singh TS, Verma TN. An assessment study of using Turel Kongreng (river mussels) as a source of heterogeneous catalyst for biofuel production. Biocatal. Agricult. Biotechnol. 2019;20:101185. [40] Shrivastava P, Verma TN. An experimental investigation into engine characteristics fueled with Lal ambari biodiesel and its blends. Thermal Sci. Eng. Progress 2019:100356. [41] Subhaschandra ST, Verma TN. Biodiesel production from Momordica Charantia (L.): Extraction and engine characteristics. Energy 2019;189:116198. [42] Salam S, Verma TN. Appending empirical modelling to numerical solution for behaviour characterisation of microalgae biodiesel. Energy Convers Manage 2019;180:496–510. [43] Nautiyal P, Subramanian KA, Dastidar MG. Production and characterization of biodiesel from algae. Fuel Process Technol 2014;120:79–88. [44] Singh TS, Verma TN. Taguchi design approach for extraction of methyl ester from waste cooking oil using synthesized CaO as heterogeneous catalyst: Response surface methodology optimization. Energy Convers Manage 2019;182:383–97. [45] Subhaschandra ST, Verma TN, Nashine P, Shijagurumayum C., BS-III Diesel Vehicles in Imphal, India: An Emission Perspective, Springer Nature Singapore Pte Ltd; ISBN: 978-981-10-7184-3. [46] Samuel OD, Okwu MO, Semiu TA, Verma TN, Afolalu SA. Production of fatty acid ethyl esters from rubber seed oil in hydrodynamic cavitation reactor: Study of reaction parameters and some fuel properties. Ind Crops Prod 2019;141:111658. [47] Subhaschandra ST, Verma TN. An analysis on the effect of temperature on the morphology of egg shell CaO catalyst: Caytalyst production for biodiesel preparation. Scietia Iranica 2019. in press. [48] Rajak U, Nashine P, Verma TN. Characteristics of microalgae spirulina biodiesel with the impact of n-butanol addition on a CI engine. Energy 2019. in press.

20