An Investigation of Air-Gas Mixer Types Designed for Dual Fuel Engines: Review

Abstract

Diesel engines produce high emissions of smoke, particulate matter and nitrogen oxide. The challenge today is to reduce exhaust emissions without making any major modifications on engine. Therefore, adding alternative fuel will be the best practical pick to improve the performance and cut down emissions from diesel engines. The air fuel mixer plays an important role to convert diesel engine to work with dual fuel mode (alternative fuel-diesel) without any change in engine. One problem of gaseous mixers is the disabilityto prepare a homogeneous air-fuel mixture at a specific air-fuel ratio before entering the engine, thereby leading to high brake specific fuel consumption and exhaust emissions. This study offers an overview of air fuel mixer types. According to, overview in the dual-fuel engines, the combustion efficiency, engine performance and the emission reduction of gases are directly proportional to the degree of homogeneous mixing and air fuel ratio, all that depend on the design of mixer (size, shape, number of holes) and control mechanism that control on the mixer.

Full text

HC
CO NOx SO2 PM
Pollutant emissions
≅
1%
N
2
≅
67%
CO
2
≅
12%
H
2
O
≅
11%
O
2
≅
9%

4.5
1.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
Emissions (g/km)
Euro 1
83%
Euro 6
Years
PM
CO
HC+NOx
Diesel fuel
injection
Exhaust
Air and natural
gas mixture

Piston
Gaseous
fuel
Air
Mixer
Manifold
(a)
Injector
Piston
Gaseous
fuel
Air
Manifold
(c)
Air
Piston
Gaseous
fuel
Manifold
(b)
Injector
Air
Piston
Manifold
(d)
Injector
Gaseous
fuel
Air

CSO
15.00
25.00
45.00 85.00 30.00 88.26
45.0°
18.83
R 2.00
CS
CSO
CSO
25.00
45.0°

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190
0.04
0.03
0.02
0.01
0
1.2e-010
8e-011
4e-011
0
0.08
0.07
0.06
0.05
-20 0 10 20
4 holes mixer
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.1
0.07
0.04
0.01
-20 0 10 20
8 holes mixer
Gas inlet
X-coord
CNG
Air inlet
Air inlet
CNG
Air inlet
Air inlet
CNG
(a)
(b) X-coord
Gas inlet
Z-coord
Z-coord
CNG inlet

Air inlet
Inlet
Air suction
pipe
Gas
Carboretor
Outlet
Gas inlet
Gas nossle
Flange
Engine inlet
manifold
Air
Hand control
value
Gas inlet
Air-gas
mixture
Gas carboretor
Air
-
gas
outlet
Biogas
Air
Biogas
Mixture outlet
(a)
(c)
(b)
2.40e-01
2.26e-01
2.13e-01
1.99e-01
1.85e-01
1.71e-01
1.58e-01
1.37e-01
1.23e-01
1.10e-01
9.50e-02
8.23e-02
6.96e-02
5.49e-02
3.43e-02
2.06e-02
6.96e-03
0.00e-00
Biogas
Mixture outlet
(a)
(c)
(b)
2.40e-01
2.26e-01
2.13e-01
1.99e-01
1.85e-01
1.71e-01
1.58e-01
1.37e-01
1.23e-01
1.10e-01
9.50e-02
8.23e-02
6.96e-02
5.49e-02
3.43e-02
2.06e-02
6.96e-03
0.00e-00
Model Plane 1 Plane 2 Plane 3 Plane 4 Plane 5 Plane 6
Existing
design
(45) (a)
Existing
design
(90) (b)
Venturi
(c)
(a)
(b)
(c)
Contour of mass fraction of CH4

Throat
Air inlet
Throat contraction
Holes to meter
CNG inlet
Outlet CNG and Air
1.0e+0
9.5e-01
9.0e-01
8.5e-01
8.0e-01
7.5e-01
7.0e-01
6.5e-01
6.0e-01
5.5e-01
5.0e-01
4.5e-01
4.0e-01
3.5e-01
3.0e-01
2.5e-01
2.0e-01
1.5e-01
1.0e-01
0.5e-01
0.0e
-
01
(a)
(b)
(c)
(a)
(b)
3D Model Mesh

1.00e-00
9.41E-01
8.80E-01
8.23E01
7.64E01
7.04E-01
6.47E-01
5.88E-01
5.29E-01
4.70E-01
4.11E-01
3.52E-01
2.93E-01
2.34E-01
1.75E-01
5.76E-01
0.00e
-
01
(a)
(b)
CNG
intel
Intel
Hole at
the throat
Throat
Outlet
Contour of mass function of CH4
0.00e+00
1.00e+00
(a)
(b)

∅
92
∅ 61
220
∅
80
12×
∅
12
24×
∅
8
∞
∅
92
180
∅
92
17
180
∅
92
∅
78
36×∅
13
16
∅ 61
(a)
(b)
1.00e
-
00
9.28e-01
8.56e-01
7.84e-01
7.12e-01
6.40e-01
5.68e-01
4.96e-01
4.24e-01
3.52e-01
2.80e-01
2.08e-01
1.36e-01
6.40e-02
0.00e-00
(b) (a)
Contour of mass fraction of syngas
120 cm
Injectors
(0.5 cm)
100 cm
Throat (70 cm)
Outlet
(mixture of CNG
and air before intake
manifold)
Inlet (air)

100e+00
9.50e-01
9.00e-01
8.50e-01
8.00e-01
7.50e-01
7.00e-01
6.50e-01
6.00e-01
5.50e-01
5.00e-01
4.50e-01
4.00e-01
3.50e-01
3.00e-01
2.50e-01
2.00e-01
1.50e-01
1.00e-01
1.05e-01
0.00e+00
(a)
(b)
(c)
Contour of mass fraction of CNG

Air inlet
Producer gas inlet out
Air inlet Producer gas inlet
Outlet
(a)
(b)
Three dimension model Mesh
1.0e+0
9.5e-01
9.0e-01
8.5e-01
8.0e-01
7.5e-01
7.0e-01
6.5e-01
6.0e-01
5.5e-01
5.0e-01
4.5e-01
4.0e-01
3.5e-01
3.0e-01
2.5e-01
2.0e-01
1.5e-01
1.0e-01
0.5e-01
0.0e-01
(a) (b)
Contour of mass fraction of
producer gas

Butterfly value
Fuel inlet
Mixture
outlet
Air inlet
Orifices
(a) (b)
1.000e+000
9.000e-001
8.000e-001
7.000e-001
6.000e-001
5.000e-001
4.000e-001
3.000e-001
2.000e-001
1.000e-001
0.000e-001
Contour of mass fraction
of producer gas
(a) (b) (c)
0.
000e
-
001
Contour of mass fraction
of producer gas
(a) (b) (c)

3.147e+0.001
2.361e+0.001
1.575e+0.001
7.893e+000
3.293e+002
(a)
Vector 2
(M sˆ-1)
Contour 1
1.000e+000
9.000e-001
8.000e-001
7.000e-001
6.000e-001
5.000e-001
4.000e-001
3.000e-001
2.000e-001
1.000e-001
0.000e+000
(b)
Motor. orifices Outlet
Producer gas
inlet
Butterfly
valve
Mixing
chamber
Air inlet
(a)
(b) (c)
(b)
-4120.449 15112.600 34345.648 53578.699 72811.750
Pa
m/sec
32.287 64.574 96.862 129.149
(a)
0.000
Contour of velocity
Contour of pressure

0.000
1.000
(c) Contour of mass fraction of producer gas