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Int. J . Hydrogen Energy. Vol. 12, No. 3. pp. 177-186, 1987.Pr in ted in Grea t Br i ta in .
11361) 319 9/8 7 $3.011 + 0.00P e r g a m o n J o u r n a l s L t d .
© 1 9 8 7 I n t e r n a ti o n a l A s s o c i a t i o n f o r H y d r o g e n E n e r g y .
W A T E R I N D U C T I O N S T U D I E S IN A H Y D R O G E N - D I E S E L D U A L - F U E L
E N G I N E
G. P. PRABHUKUMARt,S. S W A M I N A T H A N * , B. NAGALINGAM*and K. V. G O P A L A K R 1 S H N A N *
* nternal Combustion Engines Laboratory, Indian Institute of Technology, Madras 600 036, Indiat Department of Mechanical Engineering, Government B.D.T. College of Engineering, Davangerc 577 004, India
(Received[or publication 27October 1986)
Abstract--Power output of a hydrogen-diesel dual-fuel engine is limited by the onset of knock as the percentage ofheat input derived from hydrogen increases beyond a certain limit. Earlier work carried out at the InternalCombustion Engines Laboratory, Indian Institute of Technology, Madras, indicates that this knock sets in when theinducted hydrogen exceeds about 60% of input energy at a pilot diesel quantity of 30% of full load diesel amount. Athigher rates of hydrogen induction, the richer hydrogen-air mixture is more prone to knocking. Hardly anyinformation is available on the possibilities of improving the knock limited power output of a hydrogen-dieseldual-fuel engine. Water can serve as a powerful internal coolant in decreasing the unburned mixture temperaturebecause of its high latent heat. This paper presents the results of our investigation on improving the knock limitedpower output when water is inducted with the intake charge of a hydrogen-diesel dual-fuel engine, The change in thecombustion characteristics are also reported.
INTRODUCTION
The present energy situation has stimulated active
research interest in non-petroleum and non-polluting
fuels, particularly for the t ranspo rtation and agricultural
sectors. Hydrogen has been suggested as a long term
alternative fuel for internal combustion engines [1].
Besides being the cleanest burn ing chemical fuel, hydro-
gen can be produced from water using non-fossilenergy sources such as nuclear and solar energy.
In In dia, compression ignition engines play a domi-
nant role in transportation and agricultural sectors,
because of their superior thermal efficiency and durabil-ity charactersitics. In fact, the diesel consumption at
present is about 16 million tonnes per year compared to
1.7 million tonnes of petrol. It is estimated that the
cons umpt ion of diesel in the year 2000 will be aroun d 45
million tonnes. Hence, there is a need for developing
altern ative fuels such as hydrogen for diesel engines. An
easy method of using hydrogen in diesel engines is the
hydrogen -diesel dual-fuel mode. It is possible to tracethe origin of the dual-fuel engines back to Dr Rudolf
Diesel who p atented the engine ru nnin g essentially on
the dual-fuel principle [2]. He stated that the amount of
gas used as the main fuel charge was limited to small
proportion s due to the loss of combustio n control. Thesignificance of his findings, however, was appreciated
only at a much later date. Commercial units of thedual-fuel type were actually put in to opera tion in 1935.
The dual-fuel combustion system features essentially
a homoge neous gas-air mixture compressed to below itsauto ign ition conditions and ignited by the inj ection of apilot liquid fuel near the top dead centre position. The
primary fuel is generally gaseous at atmospheric condi-tions and control s the power output. The pilot liquid fuel
is injected through the conventional diesel injectionequipment. Unlike the spark ignited gas engine which
requires an adequate and un inter rupt ed gas supply, the
dual-fuel type is capable of being switched over enti rely
to conventional diesel dual-fuel operation whenever
desired without interruption.
Very little information is available about the be-
haviour of hydrogen as a fuel in con ventional compress-
ion ignition engines modified to operate on the dual-fuel
type. Earlier work carried out in this laboratory byGopal and others [3] on the hydrogen-diesel dual-fuel
engine indicates that knock sets in when the inducted
hydrogen exceeds about 60% of input energy at a pilot
diesel quantity of 30% of full load diesel amount. This
paper presents some of the findings of our investigaiton
on improving the knock limited power output of a
single-cylinder hydrogen- diesel dual-fuel engine by in-
duction water along with the intake charge. The changein combustion characteristics are also reported.
EXPERIMENTAL SET UP
A single-cylinder , direct inj ection, diesel engine of 80
mm bore and 110 mm stroke was used for the ex-
perimental work. The details of the engine are given in
Appendix A. This engine was chosen for dual4uel
operation since it is a widely used type of engine in India
and has a robust construction and reliable performance.
A schematic layout of the test set up is given in Fig. 1.Hydrogen, stored at 17.5 MPa in gas cylinders was
reduced to 0.1 MPa through a pressure regulator. Then
it was passed throu gh a fine control valve, for regulatingthe am oun t of gas, a gas flow meter, a flame trap an d a
flame arrestor. The flame trap and the flame arrestor
were used to suppress the backflash into the intakemanifold. Hydrogen was inducted into the enginethrough the intake manifold. Water was injected intothe intake charge in the form of a fine spray and was
177
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178
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, q 2
I1
G. P. PRABHUKUMARe t a l .
5 • I
1 9~ 1 ~ ~ 1 8
f'-120
I-'121
Fig. 1. Schematic layout of the test set up. 1. Pressurised hydrogen gas cylinder. 2. Cylinder gas pressureregulator. 3. Control valve, fine adjustment. 4. Hydrogen gas flow meter. 5. Water flame trap. 6. Flamearrestor. 7. Air flow meter. 8. Water injection nozzle. 9. Water flow control valve. 10. Water flow meter.11. Engine. 12. Hydraulic dynamometer. 13. Pressure pick up. 14. Charge amplifier. 15. Oscilloscope. 16.Signal analyser. 17. Crank angle inductive pick up. 18. Diesel fuel tank. 19. Fuel measuring burette. 20.
Exhaust temperature meter. 21. Exhaust smoke meter.
metered on volumetric basis by the use of a water flow
meter. A Kistler piezo-electric pressure pick up fitted
into the engine combustion chamber, along with a
charge amplifier, oscilloscope and signal analyser en-
ables the measurement of cylinder pressure. Timingmark signals were generated by an electro magnetic
inductive pick up close to the en gine fly wheel. Pressure
crank angle diagrams, averaged for 100 cycles werestored in floppy discs and lat er analysed with the help of
an Iwatsu Signal Analyser to derive important combus-
tion parameters such as ignition delay, maximu m rate of
pressure rise and peak pressure. The power outpu t was
measured by a hydraulic dynamometer. Diesel and air
consumption rates were measured by standard instru-
mentatio n. The exhaust temperatur e was measured by a
thermocouple. The exhaust smoke density was mea-sured using Bosch diesel smoke meter.
EXPERIMENTAL PROCEDURE
Hydrogen was inducted through the intake manifoldkeeping the diesel flow, called the pilot quantity,
constant. This resulted in increased engine output as theengine speed was held constan t at 1500 r.p.m. All theexperimental data were recorded. Hydrogen flow rate
was then increased to a higher value and all theobservaitons were once again recorded. This was con-tinued until knock set in. These experiments wererepeated for three differen t diesel pilot quant ities of 10,
30 and 45% of full load diesel amount (Full load dieselconsumpt ion = 1.06 kg hr -1) and the co rrespondi ngknock limited power outpu t was foun d out at each diesel
pilot quantity without water induction . In order to study
the effect of water in suppressing knocking it wasinducted in the intake manifold simultaneo usly with
hydrogen induction. The above experiments were repe-
ated with water induction. Flow rate of water was varied
from 0.4 x 10 -3 to 5 x 10 -3 m 3 hr -1.
DETECT ION OF THE ONSET OF KNOCK
Dual-fuel engines are said to knock when the rate of
pressure rise following ignition is found to increase
abruptly to very high values, so high in fact that
continu ed operation u nder such conditions can result in
engine damage.
The initial introduction of small quantities of hyd-
rogen with the air charge neither affected the pressure
diagrams nor the power developed. As the hydrogen
concentration was slowly increased, the engine de-
veloped higher power at the same speed. A significant
increase in the ignition delay was observed during this
process. The ignition delay was defined as the periodbetween the start of injec tion and the first detec table risein cylinder pressure due to combustion. Further increase
in gas admission resulted in considerable increase inpower output with higher cylinder pressures. The gasconcentrations could be further increased up to a point
beyond which combustion became very rapid and aslight increase in the gas concent rati on led to ~knocking'.
As soon as it occurred, the audible sound of the enginechanged considerably. Simultaneously, the shape of the
pressure crank angle diagram changed as shown in Fig. 2exhibiting a very sharp pressure rise with much highermaximum pressure accompanied by oscillations on theexpansion curve.
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A H Y D R O G E N - D I E S E L D U A L - F U E L E N G I NE 17 9
1 I I I
TDC
W I T H O U T K N O C K I N G
I I I I
T D C
KNOCKI NGI I I IFig. 2 . Typical pressure crank angle diagram s jus t before and after the onset o f knock.
T h e t r a n s it i o n f ro m " n o r m a l' t o ' k n o c k i n g ' o p e r a t i o n
w a s q u i t e s h a r p a n d c o u l d b e a c h i e v e d b y s m a l l c h a n g e si n m i x t u r e s t r e n g t h . T h e a b r u p t c h a n g e i n t h e s h a p e o f
t h e p r e s s u r e d i a g r a m w a s u s e d a s a m e a n s f o r d e t e c t i n g
t h e o n s e t o f k n o c k [ 4].
R E S U L T S A N D D I S C U S S I O N S
EJfect of pilot quantity on the performance of a normalhydrogen-diesel dual-Juel engine
T h e p e r c e n t a g e o f h e a t i n p u t d e r i v e d f ro m h y d r o g e n
v e r s u s p o w e r o u t p u t a n d b r a k e t h e r m a l e f f i c ie n c y a t th r e e
d i f f e r e n t d i e s e l p i l o t q u a n t i t i e s a r e s h o w n i n F i g . 3. A s
e x p e c t e d a t e a c h p i l o t q u a n t i t y t h e p o w e r o u t p u ti n c r ea s e s w h e n t h e p e r c e n t a g e o f h y d r o g e n i n th e
m i x t u r e in c r e a se s . H o w e v e r , t h e m a x i m u m p o w e r t h a t is
d e v e l o p e d a t a g i v e n p i l o t q u a n t i t y i s l im i t e d b y t h e o n s e t
o f k n o c k in g . K n o c k - l i m i t e d p o w e r o u t p u t a t h i g h e r p i l o t
q u a n t i t i e s o c c u r s w i t h l o w e r p e r c e n t a g e s o f h e a t i n p u t
d e r i v e d f r o m h y d r o g e n . T h i s i s d u e t o t h e f a c t t h a t
g r e a t e r e n e r g y r e l e a s e d b y d i e s e l c o m b u s t i o n a t h i g h e r
p i l o t in j e c t i o n r a t e s , w h i c h e n a b l e s e v e n r e l a t i v e l y l e a n
h y d r o g e n - a i r m i x t u re s t o b u r n f a s t e r.
T h e b r a k e t h e r m a l e f f i c i en c y at d i f f e r e n t d i e s e l p i l o t
. 4 o I I I I3O
~ o 4~ 2 0
m 10
~t .L
aaw O,
3 . ° 0 ,. / ~ f
5
0 15 30 .45 60
I I
/
i I i 1 I75 90
I I I
DI ESEL P I LOT
Q U A N T I T I E S
o 10 % F .L
& 3 0 % F . L
, 4 5 % F . L
C . R = 1 6 . 5
S P E E D - - 1 5 0 0 ( r p r n )o
I N J . T I M I N G - - 2 7 b T D C
~ K N O CK L IMI T
P E R C E N T A G E O F H E A T I NP UT D E R I V E D F R O M H Y D R O G E N
I I
I
Fig. 3 . Effect of diesel pi lot quant i ty on the perform ance.
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180
7 . 0W
u3~n ~ 6.0
L d 0n- ~I.
o. E
x ~ 5 . 0
wo_
0 . 3
o E - < 0 . 2w o
× w~ EO. ~< f n -
35>-
<
~ 30
~ 2 5
20
0 15 30 L5 60
G. P. PR AB HU KU MAR et al.
[
//
I7 5 9 0
40
3O
~ 2 0 - -rr"
U > -- t O
~ - w Z 1 0w ~v
n , " I _
m w 0
I IDI ESEL P I LOT
QUANT I T IES
o 10 % F.L
A 3 0 % F . L
, Z,5 °/o F.L
C . R = 1 6 . 5
S P E E D = 1 5 00 r p m )
INJ. TIM ING = 27 ° bTDC
K N O C K L I M I T
I I 1 IP E R C E N T A G E O F H E AT I NP U T D E R I V E D F R O M H Y D R O G E N
Fig. 4. Effect of diesel pilot quantity on combustion characteristics.
I f ] I ~ [ I l f 1DI ESEL P I LOT
Q U A N T I T Y = I 0 % E L .
C . R . = 16 . 5
S P E E D = 1 5 0 0 ( r p m )
I NJ. T I M I NG = 27 °bT D C
W ATER I NJ . RATE
o N O R M A L
A 0 . 4 x 10 - 3m 3/ h r
• 0 . 7 , ,
V 0 . 9 , ,
K N O C K L I M I T
3.0(3 ~
I I I I I I I0 . 0 0 ~ _ _
76 78 80 82 84 86 88 90 92 94 96P E R C E N T A G E O F H E A T I N PU T D E R I V E D F R O M H Y D R O G E N
F i g . 5. E f f e c t o f w a t e r i n d u c t i o n o n t h e p e r f o r m a n c e a t ] 0 % o f f u l l lo a d d i e s e l a m o u n t .
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181
/.0
quantities is almost constant at the same power output .
The variation of ignition delay, maximum rate of
pressure rise and peak pressure with percentage of heat
input derived from hydrogen at different pilot quantities
are shown in Fig. 4. It is noted that at lower pilot
quantity of 10% full load diesel amount the ignition
delay of the pilot fuel decreases with the addition ofhydrogen. However there is not much change in the
ignition delay with increase in percentage of hydrog en at
higher pilot quanti ties. It can be seen that the maximum
rate of pressure rise and peak pressures increase at
higher percentage of hydrogen because of the greaterinitial energy being released at higher pilot quantities.
It is observed that the knock limited power output
occurs when the percentage of heat i nput derived from
hydrogen is about 84, 60 and 50% at the diesel pilot
quant ities of 10, 30 and 45% of full load diesel amount .
E f f e c t o f w a t e r i n d u c t i o n o n t h e p e r f o r rn a n c e
Fig. 5 compares the power ou tput and brake thermal
efficiency of the hydrogen -diesel dual-fuel engine with
and without the induction of water at a diesel pilot
quantity of 10% of full load diesel amount. Induct ion of
water into the intake manifold along with hydrogen
increases the knock limited power ou tput as it serves as
the powerful internal coolant in decreasing the un-
burned mixture temperature. The percentage of heat
input derived from hydrogen at knock-limited power
output increases to 85.7 and 87.5% for the water
ind uct ion rate of 0.4 x 10 -3 to 0.7 x 10 -3 m3hr -1
respectively. It is observed that the percentage increase
in knock limited power outpu t is about 19 and 39% forthe water in ducti on of 0.4 x 10 -3 and 0.7 x 10 -3 mShr - l
respectively. More than 0.7 × 10 -3 m3hr -~ of water
induction rate did not result in further impro vement inthe knock limited power ou tput.
In comparison to normal hydrogen-diesel dual-fuel
operatio n, power output decreases with water induction
for the same percentage of heat input derived from
hydrogen. The reduction in power is particularly notice-
able at light loads. Water addition is expected to
influence the compress ion stroke characteristics [5]. The
temperature of the mixture is lowered at the start of
compression and this is expected to extend the delay
period. Vaporization of the water decreases the effec-
tive polytropic expone nt of compression resulting in a
greater drop in the temper ature of the mixture at the endof the compression stroke. A drop in overall flame
temperature would be expected with a consequent
decrease in the flame speed. Moreover the flame would
not sweep throughout the combustion chamber and a
layer of a fuel-air mixture adjac ent to the chamber walls
would fail to burn because of quenching. Increasing the
amount of water added to the intake charge is expected
to thicken this quench layer, thereby c ontributi ng to theloss of power.
Brake thermal efficiency decreases with induction of
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2.25
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A HYDROGEN-DIESEL DUAL-FUEL ENGINE
D I E S E L P I L O T
O U A N T I T Y = 3 0 % F .L ,
C. R = 1 6 . 5
S P E E D = 1 5 00 ( r p m )
I N J . T I M I N G = 2 7 ° b T D C
W A T E R I N J. R A T E
o N O R M A L
A 0 . Z, X 1 0 3 m 3 / h r _ _
• 0 . 7 0 ,
7 0 . 9 , ,
~ KNOCK LIMIT
1 l I _ 1 _ _ _10 2 0 3 0 Z ,0 5 0 6 0 7 0 8 0 9 0 10 0
P E R C E N T A G E O F H E A T IN P U T D E R I V E D F R OM H Y D R O G E N
Fig. 6. Effect of water induction on the performance at 30% of full load diesel amount.
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l
G. P. PRABHUKUMAR e t a l .
I I I I 10
30
~ 20n.-
~ . - - z
m 10
O2u..
m m 0
3.00
5 2.25
a: ~ 1.50
o 0 . 7 s
I I I 1DIESEL PILOT
QUANTITY : 45% EL.
C.R : 16.5
SPEED = 1500 ( r p m)INJ. TIMING =27°bTDC
WATER INJ. RATE
o NORMAL
& 0.4 x 10-3rn 3/hr
• 0.7 ,,
7 0.9 ,,
I KNO CK LIMIT
o . o o I I I I I I I I10 20 30 Z,0 50 60 70 80
PERCENTAGE OF HEAT INPUT DERIVED FROM HYDROGEN
I I90 100
Fig. 7. Effect of water induction on the performance at 45% of full load diesel amount.
o . 0 I I I I I I(
u3
u~ -- 5.0LLIn,"
0_ E
~'~ /-,.C.<U.l0_ 'A V
~: ~ o.1.
Z
_o
~0 I 1 I76 78 80 82 84 86 88 90 92PERCENTAGE OF HEAT INPUT DERIVED FROM HYDROGEN
I I I lDIESEL PILOT
QUANTITY = 10% F.L.
C.R. = 16.5
SPEED = 1500 ( rpm )o
INJ.T IMING = 27 bTDC
WATER INJ. RATE
o NORMAL
A 0. Z, x 10-3m3/hr
• 0 . 7 ,,
V 0.9 ,,
KNOCK LIMIT
I I94 96
Fig. 8. Effect of water induction on combustion characteristics at 10% of full load diesel amount.
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A HYDROGEN-DIESEL DUAL-FUEL ENGINE 183
7.0k13C~
t ntn~ 6.0LO t3
CI~ O~
a. E" ~ 5 . [<
k13a_
/,.0
laJ
0 . 3 ~LO:__ W °
O_
0.1 __
>-
<
-3
w_ 30C3
<
Z tO
CIo
~ 25__
V
.------- V
V ~ V ~
I 1 I IDI ESEL P I LOT
Q U A N T IT Y = 3 0 % F . L .
C . R . = 16 . 5
S P E E D = 1 5 0 0 ( r p m )
I NJ . T I M I NG = 27°bTDC
W A T E R I N J . R A T E
o N O R M A L
A 0 . / - x l 0 3 r n 3 / h r .
• 0 . 7 ,,
V 0 .9 ,,
KNOCK LIMIT
0 f l I I I I I0 10 20 30 Z,0 50 60 70 80 90 100
P E R C E N T A G E O F H E A T I N PU T D E R I V E D F R O M H Y D R O G E N
Fig. 9. Effect of water induction on combustion characteristics at 30% of full load diesel amount.
water for the same input of hydrogen energy. Wateraddition allows more gaseous fuels to escape the com-
bustion process as a result of the q uenching due to the
reduction in the cycle tempera ture as explained above.
Hence, the br ake thermal efficiency decreases with the
induction of water, However, addition of water in-
creases the brake thermal efficiency in the range beyondthe knock limited power output of the normal
hydrogen -diesel and dual-fuel engine.
As seen in Fig. 6, at the pilot quantity of 30% of full
load diesel amount, the percentage increase in the knock
limited power output is about 8.7 and 11% for theinducted water rate of 0.4 x 10 3 an d 0.7 x 10 -3 m3hr -1
respectively. It is observed that though the increased
water induction results in the impreved knock limitedpower outp ut, the lubricating oil was diluted. The
percentage increase in the knock limited power out put is
6.7 and 10% for the inducted water flow rate of 0.4 x10 3 an d 0.7 x 10 3 m 3 hr . / a t a diesel pilot quant ity of
45% of full load diesel (Fig. 7). At 30 and 45% diesel
pilot quantity also similar trends in the performance areobserved as in the case of 10% diesel pilot quantity.
Effect of water induction on the combustion
characteristics
The effect of water addition on the ignition delay,
maximum rate of pressure rise, and p eak pressures in a
hydrog en-diese l dual-fuel engine is shown in Figs 8, 9
and 10 for three differen t diesel pilot quantities of 10, 30and 45% of full load diesel. Cooling of the compressed
charge due to the water addition increases the ignition
delay at a particular diesel pilot quantity.
In comparison to normal hydrogen-diesel dual-fuel
engine, the maximum rate of pressure rise and peak
pressure decrease with water induct ion due to the slower
combustion rates. Water addition decreases the mixturetemperature at the end of compression, resulting in a
drop in the overall flame temperature with a consequent
decrease in flame speed.The variation of knock limited power output with
water induction is shown in Fig. 11. It is observed that
the knock limited power o utput increases with increased
rate of water induction. The optimum water induction
rate for improved knock limited power o utput is foundto be 0.7 × 10 -3 m3hr -1 at all the th ree diesel pi lot
quant ities of 10, 30 and 45% of full load diesel amount .
Imbricating oil quality was found to deteriorate when
the water induction rate was increased beyond 0.7 ×10 -3 m3hr -1"
Figure 12 shows the typical pressure-crank angle
diagrams at the same operating conditions with andwithout water induction for all the three diesel pilot
quant ities of 10, 30 and 45% of full load diesel amount.
It is clearly seen that water addition suppresses knockingbecause of reduced temperature of the unburned mix-
ture.The exhaust temperat ure with water inductio n of 0.7
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1 8 4 G . P . PRABHUKUMAReta l .
h i
U 3~ 7.0
L d ot3~ d~.
o_ E
~ - - 6 . 0
b J
5 , 0 _ _
W
o ~ oc~0.z,W
>~ ~ E 0 .3
0 .2
> -
<uw ~ 2 5o
z uo o
~ 20
I 1 I I I I
15
I I I ID I E S E L PI L OT
QU AN TIT Y -- 45 % F-. L ,
C . R . = 1 6 . 5
S P E E D - - 1 5 0 0 ( r p m )
I N J . T I M I N G = 2 7 ° b T O C
W A T E R I N J , R A T E
o N O R M A L
z& 0. Z, x 10"3m 31 h r
• 0 . 7 , ,
7 0 . 9 , ,
K N O C K L I M I T
I I I I I I I I I I9O 1000 10 20 30 40 50 60 70 8 0
P E R C E N T A G E OF" H E A T I N PU T D E R I V E D F R O M H Y D R O G E N
F i g. 1 0. E f f e c t o f w a t e r i n d u c t i o n o n c o m b u s t i o n c h a r a c t e r i s ti c s a t 4 5 % o f fu l l l o a d d i e s e l a m o u n t .
3 , 7 5
3 . 0 0
0 _
O
pc .
L U
o 2 . 2 50 _
a
L U
d
u 1.50OZ"- z
I 1 I I
_ _ D I E S E L P I LO T
Q U A N T I T I E S
C .R -- 16. 5 o 10 °/o F. L
S P E E D -- 1 50 0 ( r p m ) A 3 0 % F . L
INJ. T IM ING : 27°bTDC • 45 % F .L
0 7 5 I I I I0 0 .5 1 .0 1 ,5 2 .0
W A T ER F L O W R A T E ( x 1 0 " 3 m 3 / h r )
F i g . I I . V a r i a t i o n o f k n o c k - l i m i t e d p o w e r o u t p u t w i t h w a t e r i n d u c t i o n .
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A HYDROGEN-DIESEL DUAL-FUEL ENGINE
D I E S E L P I L O T
Q U A N T IT Y = 1 0 % F . L
I I I I I i
D
I L I t I I
I 1 1 I I 1
I l i l ) l
I I
D I E S E L P I L O T
Q U A N T I T Y = 3 0 % F . L
1 I I ~ t [
l _ l _K N O C K S
T - [ - - - -
I t t I
N O K N O C K I N G .
I I I I I I I I IW I TH O U T W A T E R A D D I T I O N
] ~ - T - F - F I - - I - - ] ~ - -
I I f I I I I
D I E S E L P I L O T
OUANTITY = /. 5 % F .L
I I
I I I I I I I I
I I I 1 1 I I I
I I I I 1 I I
W A T E R F L O W R A T E s 0.7x 1 0 3 m 3 / h r .
Fig. 12. Typical pressure crank angle diagrams and without the addition of water at the same operatingconditions.
185
× 10 -3 m3hr -I is about 30°C lower t han the norma l
hydrogen-diesel dual-fuel operation. Exhaust smoke
density was found to be almost negligible at all opera ting
conditions in a hydrogen-diesel dual-fuel engine with
and without water induction.
CONCLUSIONS
The following conclusions are drawn based on our
experimental investigations in a h ydrogen~ liesel dual-
fuel engine with water induction.
(1) Under nor mal hydrogen-di esel dual-fuel opera-
tiom the knock-limited power outpu t occurs when the
percentage of heat in put derived from hydrogen is about
84, 60 and 50% at the diesel pilot quant ities of 10, 30 and
45% of full load diesel amount.
(2) Inducti on of water into the intake manifold along
with hydrogen increases the knock-limited power out-
put, as it serves as a powerful internal coolant in
decreasing the unburned mixture temperature. The
percentage of heat input derived from hydrogen atknock-limited power output increases to 87.5, 65 and
53.5% at the diesel pilot quanti ties of 10, 30 and 45% forthe water induc tion rate of 0.7 x 10 3 m3hr-~.
(3) In comparison to normal hydrogen-diesel dual-
fuel operation, the knock-limited power output in-o ~ ~ 1creases by abou t 39, I 1 and 10 g,, with 0.7 x I0-- m- hr -
of full load diesel amount.(4) Brake thermal efficiency as well as power outpu t
decreases with the inductio n of water due to the escape
of gaseous fuel during combustion process as a result of
quenching at the same heat input derived from hyd-
rogen. However, addition of water increases the brake
thermal efficiency beyond the knock-limited power
output of nor mal hydrogen -diesel dual-fuel engine.
(5) Ignition delay increases with the addition of water
due to cooling of the charge at the end of compression .
(6) Maximu m rate of pressure rise and peak pressures
decrease with water induction due to slow combustion
rate.
(7) The optim um water induction rate for improvedknock limited power out put is found to be 0.7 × 10 -3
m3hr -I at all the three diesel pilot quanti ties of 10, 30
and 45%. More than 0.7 x 10 -3 m3hr i of waterinduction causes d eterioration in lubricating oil quality
even though it improves .the knock limited poweroutput.
Acknowledgements--The authors thank the Dept of Science &Technology and Dept of Non-Conventional Energy Sources,Govt. of lndia for the financial assistance to carry out thisresearch work on hydrogen fueled engine studies.
REFERENCES
1. Kenneth E. Cox and K. D. Williamson Jr, ttydrogen--ltsTechnology and Implications, Vol. IV (1979).
2. R. L. Boyer, Status of dual-fuel engine development.SAE Journal 57, 46--48 (1949).
8/7/2019 co-injeção diesel H2 2
http://slidepdf.com/reader/full/co-injecao-diesel-h2-2 10/10
186 G . P . P R A B H U K U M A R e t al.
3. G. Gopal , P. Srinivasa Rao, K. V. Gopalakri shnan and B.S. Murthy. Use of hydrogen in dual-fuel engines. In t . J .
H y d r o g e n E n e r g y 7,267-272 (1982).4. G. A. Karim, S. R. Klat and N. P. W. Moore, Knock in
dual-fuel engines. Pro c . In s t . Me c h l . En g rs 181, 453-466
(1967).
5. G. A. Karim and N. Amoozegar, Examination of theperformance of dual-fuel diesel engine with particular
reference to the presence of some inert diluents in theengine intake charge. SAE Paper 821222 (1982).
6. G. A. Karim and S. R. Klat, The knock and auto ignition
characteristics of some gaseous fuels and their mixtures. J.Inst . Fue l . 39, 109-119 (1966).
APPENDIX A
En g in e S p e c i f i c a t io n s
Make AV1 Kirloskar EngineType Single cylinder, water cooled, direct injec.
tion vertical diesel engine.
Rated output 3.68 kW at 1500 r.p. m.Bore 80 mm
Stroke 110 mmDisplacement 553 cm3
volume