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8/7/2019 cobustion analysis with dual fuel
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Combustion analysis on a DI diesel engine with hydrogen in dual fuel mode
N. Saravanan *, G. Nagarajan, G. Sanjay, C. Dhanasekaran, K.M. Kalaiselvan
Department of Mechanical Engineering, Internal Combustion Engineering Division, College of Engineering, Guindy, Anna University, Chennai 600 025, India
a r t i c l e i n f o
Article history:
Received 25 January 2008
Received in revised form 4 July 2008
Accepted 8 July 2008Available online 3 August 2008
Keywords:
Hydrogen
Port injection
Diethyl ether
Dual fuel
Emission
a b s t r a c t
Hydrogen is expected to be one of the most important fuels in the near future to meet the stringent emis-
sion norms. In this experimental investigation, the combustion analysis was done on a direct injection
(DI) diesel engine using hydrogen with diesel and hydrogen with diethyl ether (DEE) as ignition source.
The hydrogen was injected through intake port and diethyl ether was injected through intake manifold
and diesel was injected directly inside the combustion chamber. Injection timings for hydrogen and DEE
were optimized based on the performance, combustion and emission characteristics of the engine. The
optimized timing for the injection of hydrogen was 5° CA before gas exchange top dead center (BGTDC)
and 40° CA after gas exchange top dead center (AGTDC) for DEE. From the study it was observed that
hydrogen with diesel results in increased brake thermal efficiency by 20% and oxides of nitrogen (NO x)
showed an increase of 13% compared to diesel. Hydrogen-DEE operation showed a higher brake thermal
efficiency of 30%, with a significant reduction in NO x compared to diesel.
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
The internal combustion engines have already become an indis-pensable and integral part of our present day life. In recent days
the importance of environment and energy are emphasized in var-
ious energy schemes [1]. Increase in stringent environment regula-
tions on exhaust emissions and anticipation of the future depletion
of world wide petroleum reserves provide strong encouragement
for research on alternate fuels [2]. Hydrogen is one of the most
promising alternate fuels. It’s clean burning characteristics and
better performance drives more interest in hydrogen fuel [3]. Many
researchers have used hydrogen as a fuel in spark ignition (SI) en-
gine [4]. A significant reduction in power output was observed
while using hydrogen in SI engine In addition pre ignition, backfire
and knocking problems were observed at high load. These prob-
lems have resulted in using hydrogen in SI engine within a limited
operation range [5,6]. However hydrogen cannot be used as a sole
fuel in a compression ignition (CI) engine, since the compression
temperature is not enough to initiate the combustion due to its
higher self-ignition temperature [7]. Hence an ignition source is re-
quired while using it in a CI engine. The simplest method of using
hydrogen in a CI engine is to run in the dual fuel mode with diesel
as the main fuel or Diethyl Ether can be used that can act as an
ignition source for hydrogen. In a dual fuel engine the main fuel
is either inducted/carburated or injected into the intake air stream
with combustion initiated by diesel. The major energy is obtained
from diesel while the rest of the energy is supplied by hydrogen.
The hydrogen operated dual fuel engine has the property to
operate with lean mixtures at part load and no load, which results
in NO x reduction, with an increase in thermal efficiency therebyreducing the fuel consumption. It was also observed that hydrogen
could be substituted for diesel up to 38% on volume basis without
loss in thermal efficiency, however with a nominal power loss.
Hydrogen used in the dual fuel mode with diesel by Masood et
al. [8] showed the highest brake thermal efficiency of 30% at a com-
pression ratio of 24.5. Lee et al. [9] studied the performance of dual
injection hydrogen fueled engine by using solenoid in-cylinder
injection and external fuel injection technique. An increase in ther-
mal efficiency by about 22% was noted for dual injection at low
loads and 5% at high loads compared to direct injection. Lee et al.
[10] suggested that in dual injection, the stability and maximum
power could be obtained by direct injection of hydrogen. However
the maximum efficiency could be obtained by the external mixture
formation in hydrogen engine. Das et al. [11] have carried out
experiments on continuous carburation, continuous manifold
injection, timed manifold injection and low pressure direct cylin-
der injection. The maximum brake thermal efficiency of 31.32%
was obtained at 2200 rpm with 13 Nm torque. Hashimoto et al.
[12] have done extensive experimental investigation with DEE
and diesel used as ignition source for igniting hydrogen fuel. Table
1 shows the properties of hydrogen in comparison with diesel and
DEE. Fig. 1 shows the photograph of hydrogen and DEE flow
arrangements.
Electronic injectors for hydrogen can have a greater control over
the injection timing and injection duration with quicker response
to operate under high-speed conditions [13]. The advantage
of hydrogen injection over carburated system is problems like
0016-2361/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.doi:10.1016/j.fuel.2008.07.011
* Corresponding author. Tel.: +91 9881128166.
E-mail address: [email protected] (N. Saravanan).
Fuel 87 (2008) 3591–3599
Contents lists available at ScienceDirect
Fuel
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / f u e l
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backfire and pre ignition can be eliminated with proper injection
timing [14]. The photographic view of the hydrogen injector posi-
tion on the cylinder head is shown in Fig. 2 and the photographic
view of the hydrogen and DEE injector position on the intake man-
ifold is shown in Fig. 3. Fig. 4 shows the cross sectional view of the
hydrogen injector.The distinguished feature of hydrogen-operated engine is that it
does not produce major pollutants such as hydrocarbon (HC), car-
bonmonoxide (CO), sulphur dioxide (SO2), lead, smoke, particulate
matter, ozone and other carcinogenic compounds. This is due to
the absence of carbon and sulphur in hydrogen. However hydro-
gen-operated engines suffer from the drawback of higher NO x
emissions that has an adverse effect on the environment. The for-
mation of NO x could be due to the presence of nitrogen in the fuel
and air and also the availability of oxygen in the air. In the case of
hydrogen it is obvious that NO x is due to the nitrogen present in air
[15]. When the combustion temperature is high some portion of
nitrogen present in the air reacts with oxygen to form NO x. One
of the ways of reducing NO x is to operate the hydrogen engine with
lean mixtures. Lean mixture results in lower temperature thatwould slower the chemical reaction, which weakens the kinetics
of NO x formation [16,17]. NO x emissions increase with increase
in equivalence ratio and peaks at an equivalence ratio of 0.9.
The objective of the present work is to use hydrogen (by injec-
tion in the intake port) in the following ways and study the perfor-mance, combustion and emission characteristics and compare with
baseline diesel:
1. Hydrogen in the dual fuel mode with diesel.
2. Hydrogen with diethyl ether as an ignition source.
2. Experimental setup and procedure
The test engine used was a single cylinder water-cooled DI die-
sel engine, having a rated power of 3.7 kW that runs at a constant
speed of 1500 rpm which was modified to work with hydrogen in
the dual fuel mode. The specifications of the test engine are given
in Table 2. Fig. 5 shows the schematic view of the experimental set-
up. The flow diagram for hydrogen and DEE is shown in Fig. 6. Thefuel injector was controlled by means of an electronic control unit
(ECU). An Infrared detector was used to give signals to the ECU for
injector opening based on the preset timing and also to control the
duration of injection. The injection timing and injection duration
can be varied with the help of ECU. Hydrogen flow was taking place
based on the preset value. A pressure regulator as well as a digital
mass flow controller controlled the flow. Table 3 shows the techni-
cal specifications of the hydrogen injector.
In the experimental investigation first the injection timing and
injection duration for hydrogen were optimized. For this injection
timing from 5° CA before ignition top dead center (BITDC) to 25°
CA after ignition top dead center (AITDC) in steps of 5° CA was ta-
ken with hydrogen injection duration of 30° CA. 60° CA and 90° CA
at a constant hydrogen flow rate of 5.5 liters per minute. The nextstep in the investigation was optimizing the hydrogen flow. For
this hydrogen was varied from 1.5 liters per minute to 9 liters
per minute insteps of 1.5 liters per minute for the entire load con-
ditions. The optimized conditions for hydrogen based on the per-
formance, emission and combustion characteristics are as follows.
Hydrogen injection timing 5° BGTDC.
Hydrogen injection duration 30° CA.
Hydrogen flow rate 7.5 liters per minute.
3. Instrumentation
An electrical dynamometer with 10 kW capacity with a current
rating of 43.5 A was used as a loading device. A non-dispersive in-fra red (NDIR) type exhaust gas analyzer (Qrotech make) was used
Nomenclature
J/° Joules per degreekg/h kilograms per hourkW kilowattsmm millimetercm3 cubic centimeter
Abbreviations
PPM parts per millionDEE diethyl etherBSN Bosch smoke numberTDC top dead centerBGTDC before gas exchange top dead centerCAD crank angle durationDI direct injection
CI compression ignitionSI spark ignitionECU electronic control unitDFC digital mass flow controllerIR infra red
NRV non-return valveDSO digital storage oscilloscopeLPM liters per minuteUBHC unburned hydro carbonsNO x nitrogen oxidesCO carbon monoxideBTDC before top dead centerCA crank angleHHR heat release rate
Table 1
Properties of hydrogen in comparison with diesel and DEE
Sl. No. Properties Diesel Hydrogen DEE
Formula CnH1.8nC8–C20 H2 C2H5OC2H5
1 Auto ignition temperature (K) 530 858 433
2 Minimum ignition energy (mJ) – 0.02 –
3 Flammability limits (volume %
in air)
0.7–5 4–75 1.9–36.0
4 Stoichiometric air fuel ratio
on mass basis
14.5 34.3 11.1
5 Molecular weight (g mol) 170 2.016 74
6 Limits of flammability
(equivalence ratio)
– 0.1–7.1 –
7 Density at 160 C and 1.01 bar
(kg/m3)
833–881 0.0838 713
8 Net heating valve MJ/kg 42.5 119.93 33.9
9 Flame velocity (cm/s) 30 265–325 –
10 Quenching gap in NTP air (cm) – 0.064 –
11 Diffusivity in air (cm2/s – 0.63 –
1 2 Octane numb er
Research 30 130 –
Motor – – –
13 Cetane number 40–55 – >125
14 Boiling point (K) 436–672 20.27 307.4
1 5 Viscos ity at 1 5.5°C, centipoise 2.6–4.1 – 0.023
16 Vapour pressure at 38°C kPa Negligible – 110.3
17 Specific gravity 0.83 0.091 –
3592 N. Saravanan et al./ Fuel 87 (2008) 3591–3599
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for the measurement of HC, CO, NO and CO2 emissions. Technovi-
sion analyzer was used for the measurement of NO2 emission. NO x
emission was determined by adding NO and NO2 emissions. Boschtype smoke meter was used to measure smoke intensity. The ex-
haust gases were filtered and dehumidified by the exhaust gas ana-
lyzer before measurement. The gas analyzer was calibrated by
passing a known amount of span gases and readings were taken
with variation in span gas concentration. If the deviations are out-
side the accuracy limits the analyzer was calibrated by adjusting
the knob for the specific gases. The cylinder pressure was mea-
sured using a piezoelectric pressure transducer which has a pres-
sure range of 250 bar and a charge amplifier and the pressure
data were given as input to the oscilloscope for further analysis.
A Kistler make crank angle encoder with an accuracy of 1° was
used for crank angle measurement. After 30 min of engine running
on stabilized condition the pressure data were collected. The pres-
sure data’s were collected for 1000 cycles by using Yokogawa dataacquisition system. The mass flow of hydrogen was measured
using a digital mass flow controller, which controlled and mea-
sured the flow in liters per minute. The engine was operated at a
constant speed of 1500 rpm at all loads with torques correspond-
ing to full load percentages.
4. Error analysis and estimation of uncertainity
All measurements of physical quantities are subject to uncer-
tainties. Uncertainty analysis is needed to prove the accuracy of
the experiments. In order to have reasonable limits of uncertainty
for a computed value an expression was derived as follows:
DR ¼oR
o x1
D x1
2
þoR
o x2
D x2
2
þ Á Á Á þoR
o xn
D xn
2" #1=2
ð1Þ
Using Eq. (1) the uncertainty in the computed values such as
brake power, brake thermal efficiency and fuel flow measurements
were estimated. The measured values such as speed, fuel time,
voltage and current were estimated from their respective uncer-
tainties based on the Gaussian distribution. The uncertainties in
the measured parameters, voltage (DV) and current (DI), method,were ±10 V and ±0.16 A, respectively. For fuel time (Dtr) and fuel
Fig. 1. Photographic view of the hydrogen and DEE flow arrangement.
Fig. 2. Photographic view of the hydrogen injector position on the cylinder head.
Fig. 3. Photographic view of the hydrogen and DEE injector position on the intake
manifold.
Fig. 4. Cross sectional view of the hydrogen injector.
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volume (Dt), the uncertainties were taken as ±0.2 s and ±0.1 s,
respectively.
A sample calculation is given below
Speed, N = 1500 rpm.
Voltage, V = 230 V.
Current, I = 12 A.
Fuel volume, fx = 10 cc.
Brake power, BP = 4.4 kW.
BP ¼VI
gg  1000kW
BP ¼ f ðV ; I Þ
oBP
oV ¼
I
ð0:85 Â 1000Þ¼ À
16
ð0:85 Â 1000Þ¼ 0:0188
oBP
oI ¼
V
ð0:85 Â 1000Þ¼
230
ð0:85 Â 1000Þ¼ 0:2705
DBP ¼
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffioBP
oV Â DV
2
þoBP
oI Â DI
2s 2
435 ð2Þ
¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffið0:0188 Â 10Þ2þ ð0:2705 Â 0:16Þ
2
q ¼ 0:1929 kW
Therefore, the uncertainty in the brake power from Eq. (2) is
±0.1929 kW and the uncertainty limits in the calculation of B.P
are 4.4 ± 0.1929 kW. The percentage of uncertainty for the mea-
surement of speed, mass flow rate, NO x, hydrocarbon, smoke and
pressure is given below:
(i) Speed: 1.5.
(ii) Mass flow rate of air: 1.9.(iii) Mass flow rate of diesel: 2.1.
(iv) Mass flow of hydrogen: 1.8.
(v) NO x: 2.7.
(vi) Hydrocarbon: 3.2.
(vii) Smoke: 2.0.
(viii) Pressure: 3.2.
5. Results and discussion
Experiments were carriedout with hydrogen and diesel in dual
fuel operation and with DEE. The engine was not able run beyond
75% load in hydrogen DEE mode due to severe knocking. This is
attributed to the instantaneous combustion of both hydrogen
and DEE. The numerical values of the results are given in Appendix.
6. Performance characteristics
Fig. 7 shows the variation of brake thermal efficiency with re-
spect to load. It is observed that the brake thermal efficiency of
hydrogen with DEE at 75% load is 29.3% compared to diesel of
21.6%. Whereas in the case of dual fuel mode it is 26.23%. The in-
crease in brake thermal efficiency in the case of hydrogen-DEE
operation is due to higher inlet charge cooling that reduced the
temperature by about 12–15 °C due to the presence of DEE as a re-
sult of its higher latent heat of vapourisation. As the inlet charge
cools, the inlet charge (both hydrogen and air) density increases,
which in turn results in better combustion, hence an improvement
in brake thermal efficiency is noticed. The increase in brake ther-mal efficiency for hydrogen operation is due to uniformity in mix-
ing hydrogen with air [18].
Fig. 8 shows the variation of specific energy consumption with
load. The specific energy consumption of hydrogen-diesel dual fuel
is reduced by 24% for hydrogen diesel dual fuel operation at 25%
load compared to diesel. The lower specific energy consumption
for hydrogen-diesel dual fuel is due to better mixing of hydrogen
with air resulting in complete combustion of fuel. With DEE as
ignition source for hydrogen the specific energy consumption is
60% lower compared to that of base diesel. The reduction in SEC
for hydrogen-DEE dual fuel operation compared to that of hydro-
gen-diesel dual fuel is due to increased charge density because of
the presence of DEE, which reduces the intake temperature by
about 15 °C.
7. Combustion characteristics
The cylinder pressure variation is given in Fig. 9. The maximum
firing pressure obtained in hydrogen diesel dual fuel mode is 2%
higher than that obtained with diesel. The peak pressure rise cor-
responds to the large amount of fuel burnt in pre mixed combus-
tion stage and also earlier start of combustion compared to diesel
fuel. The peak pressure in the case of hydrogen with DEE reduced
by 15% than that of the base diesel. The reduction in peak pressure
is due to the use of DEE, which ignites earlier creating a hotter
environment inside the combustion chamber thereby reducing
the delay period.
Fig. 10 shows the pressure crank angle diagram for hydrogen-diesel, hydrogen-DEE dual fuel operation and base diesel at 75%
Table 2
Engine specifications
Make and model Kirloskar, AV1 make
General details Four stroke, compression ignition, constant speed,
vertical, water-cooled, direct injection.
Number of cylinders One
Bore 80 mm
Stroke 110 mm
Rated speed 1500 rpm
Swept volume 553 cc
Clearance volume 36.87 cc
Compression ratio 16.5:1
Rated output 3.7 kW at 1500 rpm
Injection pressure 205 bar
Fuel injection timing 23° BTDC
Type of combustion Hemispherical open combustion chamber
Lubricating oil SAE 20 W40
Connecting rod length 2 35 mm
1. Hydrogen cylinder 10. IR sensor for hydrogen2. Pressure regulator Electronic control unit for H2
3. Hydrogen tank 12. Engine4. Filter Dynamometer
5. Digital mass flow controller 14. Diesel tank 6. PC to control DFC 15. DEE fuel pump7. Flame trap DEE Electronic control unit
8. Flame arrester DEE Injector9. Hydrogen injector 18. IR sensor for DEE
11.
13.
16.
17.
Fig. 5. Schematic view of the experimental setup.
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load. It is observed that hydrogen diesel dual fuel mode gives a
higher peak pressure compared to base diesel fuel. The peak pres-
sure occurs 5° CA earlier than that of diesel. This might be due to
the fact that hydrogen combustion is instantaneous compared to
diesel combustion. Hydrogen with DEE as ignition source results
in a lower cylinder pressure than the base diesel fueling with peak
pressure advance of 7° CA than diesel. This may be attributed tocharge cooling due to DEE.
Hydrogen (4-5 bar)
Hydrogen tank
(150 bar)
Mass flow controller
(l/min or kg/h)
Pressure regulator
Filter
Flame trap (Visible indicator
for hydrogen flow)
Flame arrestor (Suppress fire
hazard)
Two way valve Atmosphere
Hydrogen injectorECU (Controlling
injection timings)
for hydrogen
IR detector 1
Battery Intake manifold
DEE injectorECU (Controlling
injection timings)
for DEE
Engine
IR detector 2
DEE pressure regulator
DEE fuel pump DEE tank
Fig. 6. Work flow diagram for hydrogen and DEE.
Table 3
Hydrogen injector specifications
Make Quantum technologies
Supply voltage 8–16 V
Peak current 4 A
Holding current 1 A
Flow capacity 0.8 g/s @ 483–552 kPa
Working pressure 103–552 kPa
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Fig. 11 shows the variation of heat release rate (HRR) at 75%
load. The HRR was measured with one-degree crank angle accu-
racy. It is noted that the heat release rate (HRR) is 21% higher for
hydrogen operation than the diesel fuel mode. This may be due
to the higher flame velocity of hydrogen and also due to instanta-
neous combustion. The heat released in the premixed combustion
zone is higher; this indicates the increased pressure rise in com-
bustion chamber [19]. The hydrogen with DEE mode results in
50% lesser peak heat release rate than the base diesel fuel. This
might be due to instantaneous combustion of DEE well before by20° CA than that of normal combustion of diesel.
Fig. 12 shows the rate of pressure rise at 75% load. The rate of
pressure rise is higher by about 80% in the case of hydrogen with
diesel compared to diesel fuel. The hydrogen with DEE mode re-
sults in 11% decrease in the rate of pressure rise than the base die-
sel fuel. The reduction in the rate of pressure is due to DEE that
cools the intake charge, which results in a reduction in combustion
chamber pressure.
Fig. 13 shows the cumulative heat release at 75% load condition
for hydrogen with diesel and DEE mode. The hydrogen diesel dual
fuel mode gives similar cumulative heat release pattern as that of
diesel. This might be in dual fuel mode while using hydrogen and
DEE which undergo instantaneous combustion resulting in rapid
combustion of primary fuel followed by lower diffusion period
compared to progressive combustion of diesel [20]. Hydrogen with
DEE as ignition source results in a lower cumulative heat release
than the base diesel fuel. This might be due to DEE that cools the
intake charge lowering the temperature inside the engine cylinder.
8. Emission characteristics
Fig. 14 shows the variation of NO x emission. With hydrogen-
diesel dual fuel operation NO x is 21.9 g/kW h compared to
20.65 g/kW h for diesel at 75% load. The higher concentration of
NO x is due to the peak combustion temperature [21]. With hydro-
gen-DEE the NO x emission is 0.55 g/kW h. The reduction in NO x
emission in the case of DEE operation is due to the lower peak
combustion temperature, which is due to inlet charge cooling by
around 15 °C [22].
0
5
10
15
20
25
30
35
Load,%
B r a k e t h e r
m a l e f f i c i e n c y , %
Diesel
H2 (7.5 lpm)+ DieselH2 + DEE
0 25 50 75 100
Fig. 7. Variation of brake thermal efficiency with load.
0
5
10
15
20
25
30
35
Load,%
s p e c i f i c e n e r g y c o n s u m
p t i o n ,
M J / k W h
Diesel
H2 (7.5 lpm)+ DieselH2 + DEE
250 50 75 100
Fig. 8. Variation of specific energy consumption with load.
50
55
60
65
70
75
80
85
Load,%
P e a k p r e s s u r e , b a r
Diesel
H2 (7.5 lpm)+ DieselH2 + DEE
0 25 75 10050
Fig. 9. Variation of peak pressure with load.
0
20
40
60
80
100
120
330 350 370 390 410 430 450
Crank angle, deg.
H e a t r e l e a s e r a t e ,
J / d e g . C
A Diesel
H2 (7.5 lpm)+ DieselH2 + DEE
Fig. 11. Variation of heat release rate with crank angle at 75% load condition.
0
10
20
30
40
50
60
70
80
90
250 280 310 340 370 400 430
Crank angle, deg.
P r e s s u r e , b a r
Diesel
H2 (7.5 lpm)+ Diesel
H2 + DEE
Fig. 10. Variation of cylinder pressure with crank angle at 75% load condition.
3596 N. Saravanan et al./ Fuel 87 (2008) 3591–3599
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The variation of smoke with load is shown in Fig. 15. The smoke
of 0.7 BSN is observed in hydrogen-DEE operation compared to
base diesel fuel of 2.2 BSN and 0.8 BSN for hydrogen-diesel dual
fuel at 75% load. The hydrogen on combustion produces mainly
water vapor and does not form any particulate matter due to the
absence of carbon atom, hence lower smoke level [22].
Fig. 16 shows the variation of hydrocarbon with load. The
hydrocarbon increases for hydrogen-DEE operation compared tothat of hydrogen-diesel dual fuel operation and base diesel fuel
mode. At 25% load hydrocarbon emissions are maximum, it is
2.01 g/kW h in hydrogen-DEE operation compared to both diesel
hydrogen-diesel dual fuel of 0.3 g/kW h. While using DEE the cyl-
inder charge temperature is less, which leads to a lower combus-
tion temperature, hence an increase in HC emission. At 75% load
the HC emission is found to be 0.322 g/kW h in hydrogen DEE
mode compared to diesel of 0.12 g/kW h, whereas in hydrogen-die-
sel mode it is 0.14 g/kW h. The increase in HC emission is due to
the non-availability of oxygen during diffusion combustion period,
since hydrogen and DEE undergoes instantaneous combustion as
soon as the ignition starts [23].
The variation of carbon monoxide emissions with load is shown
in Fig. 17. At 25% load condition CO emission is 1.07 g/kW h inhydrogen with DEE operation, whereas in the hydrogen diesel dual
fuel mode it is 0.43 g/kW h compared to diesel of 0.64 g/kW h. The
higher CO emission during hydrogen-DEE operation is due to the
lower combustion temperature. At 75% load the carbon monoxide
emission is 0.15 g/kW h in hydrogen-DEE operation and hydrogen
diesel dual fuel mode while that of diesel is 0.316 g/kW h.
The variation of carbon dioxide emissions with load is shown in
Fig. 18. At 25% load the CO2 emissions are 0.47 g/kW h in hydrogen
DEE operation. The hydrogen diesel dual fuel mode gives 0.84 g/
kW h compared to diesel of 1.29 g/kW h. At 75% load the carbon
dioxide emission is 0.33 g/kW h with hydrogen DEE, whereas inthe hydrogen diesel dual fuel mode it is 0.64 g/kW h compared
-3
-1
1
3
5
7
300 330 360 390 420 450
Crank angle, deg.
R a t e o f P r e s s u r e R i s e , b a r / d e g . C A
Diesel
H2 (7.5 lpm) +Diesel
H2 + DEE
Fig. 12. Variation of rate of pressure rise with crank angle at 75% load condition.
0
50
100
150
200
250
300
300 330 360 390 420 450
Crank angle, deg.
C u m u l a t i v e h e a t r e l e a s e r a t e , J
Diesel
H2 (7.5 lpm)+Diesel
H2 + DEE
Fig. 13. Variation of cumulative heat release rate with crank angle at 75% load
condition.
0
5
10
15
20
25
30
Load,%
O x i d e s o f
N i t r o g e n , g m / k W h
Diesel
H2 (7.5 lpm)+ DieselHydrogen +DEE
0 25 50 75 100
Fig. 14. Variation of oxides of nitrogen with load.
0
0.5
1
1.5
2
2.5
3
3.5
4
Load,%
S m o k e , B S N
Diesel
H2 (7.5 lpm)
+ Diesel
0 25 50 75 100
H2 + DEE
Fig. 15. Variation of smoke with load.
0
0.5
1
1.5
2
2.5
Load, %
H y d r o c a r b o n , g m / k W h Diesel
H2 (7.5 lpm)
+ Dieseldrogen a
DEE
0 25 50 75 100
H
Fig. 16. Variation of hydrocarbon with load.
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to diesel of 0.775 g/kW h. The CO2 emissions are lower compared
with the base diesel fuel, because of the absence of carbon in
hydrogen [24].
9. Conclusions
Experiments were done on a diesel engine using hydrogen in
the dual fuel mode and hydrogen with DEE as ignition source.
The optimized conditions were found to be 5° CA before gas
exchange top dead center (BGTDC) for injection of hydrogen,
30° CA for hydrogen injection duration in the dual fuel modeand 40° CA after gas exchange top dead center (AGTDC) for
DEE. The following conclusions are drawn from the present
investigation:
1. Hydrogen in both dual fuel and with DEE operation showed an
increase in brake thermal efficiency by about 22% and 35%,
respectively compared to diesel.
2. A significant reduction in NO x emissions was obtained with DEE
operation hydrogen diesel dual fuel mode as well as baseline
diesel.
3. Hydrogen diesel and DEE operation exhibited a significant
reduction in smoke emissions compared to base diesel fuel.
4. A severe knocking was noticed during the operation of the
engine with hydrogen-DEE operation beyond 75% load due tothe instantaneous combustion of hydrogen at high loads.
Appendix
S. No. Load Diesel Hydrogen-diesel Hydrogen-DEE
Brake thermal efficiency
1 28.600 11.90 15.29 17.90
2 50.000 16.85 21.48 24.30
3 78.600 21.59 25.66 29.304 100.000 23.38 25.45 –
Specific energy consumption
1 28.600 28.8 23.540 17.13
2 50.000 20.89 16.760 11.19
3 78.600 16.25 14.020 8.03
4 100.000 16.42 14.140 –
Oxides of nitrogen
1 28.600 25.34956 20.36357 0.024683
2 50.000 20.65469 21.90777 0.549102
3 78.600 17.9191 20.28236 1.267648
4 100.000 15.95163 15.8727 –
Smoke
1 No load 0.3 0 02 28.600 1.1 0 0.2
3 50.000 2 0.2 0.3
4 78.600 2.2 0.8 0.7
5 100.000 3.6 2 –
Hydrocarbon
1 28.600 0.309616 0.290265 2.012502
2 50.000 0.203984 0.192958 0.755291
3 78.600 0.124092 0.156001 0.322639
4 100.000 0.135343 0.135343 –
Carbon monoxide
1 28.600 0.647513 0.431676 1.079189
2 50.000 0.368952 0.245968 0.491936
3 78.600 0.316366 0.316366 0.1581834 100.000 0.8806 0.5661 –
Carbon dioxide
1 28.600 1.293633 0.840862 0.474332
2 50.000 0.934678 0.68871 0.38125
3 78.600 0.775098 0.640642 0.332185
4 100.000 0.752154 0.683207 –
Peak pressure
1 No load 57 52.7 51
2 28.600 65 65.5 57.75
3 50.000 71 71.3 64.8
4 78.600 78.5 78.5 68
5 100.000 82.2 82.7 –
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0
0.2
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1
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