ArticlePDF Available

Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on performance and emissions of internal combustion engines

Authors:

Abstract and Figures

Available online xxx Keywords: Hydroxy HHO-CNG Performance and emissions Pilot injection Internal combustiosn engine a b s t r a c t Energy security is an important consideration for development of future transport fuels. Among the all gaseous fuels hydrogen or hydroxy (HHO) gas is considered to be one of the clean alternative fuels. Hydrogen is very flammable gas and storing and transporting of hydrogen gas safely is very difficult. Today, vehicles using pure hydrogen as fuel require stations with compressed or liquefied hydrogen stocks at high pressures from hydrogen production centres established with large investments. Different electrode design and different electrolytes have been tested to find the best electrode design and electrolyte for higher amount of HHO production using same electric energy. HHO is used as an additional fuel without storage tanks in the four strokes, 4-cylinder compression ignition engine and two-stroke, one-cylinder spark ignition engine without any structural changes. Later, previously developed commercially available dry cell HHO reactor used as a fuel additive to neat diesel fuel and biodiesel fuel mixtures. HHO gas is used to hydrogenate the compressed natural gas (CNG) and different amounts of HHO-CNG fuel mixtures are used in a pilot injection CI engine. Pure diesel fuel and diesel fuel þ biodiesel mixtures with different volumetric flow rates are also used as pilot injection fuel in the test engine. The effects of HHO enrichment on engine performance and emissions in compression-ignition and spark-ignition engines have been examined in detail. It is found from the experiments that plate type reactor with NaOH produced more HHO gas with the same amount of catalyst and electric energy. All experimental results from Gasoline and Diesel Engines show that performance and exhaust emission values have improved with hydroxy gas addition to the fossil fuels except NO x exhaust emissions. The maximum average improvements in terms of performance and emissions of the gasoline and the diesel engine are both graphically and numerically expressed in results and discussions. The maximum average improvements obtained for brake power, brake torque and BSFC values of the gasoline engine were 27%, 32.4% and 16.3%, respectively. Furthermore, maximum improvements in performance data obtained with the use of HHO enriched biodiesel fuel mixture in diesel engine were 8.31% for brake power, 7.1% for brake torque and 10% for BSFC.
Content may be subject to copyright.
Effects of hydrogenation of fossil fuels with
hydrogen and hydroxy gas on performance and
emissions of internal combustion engines
Kadir Aydin
a,b,*
, Raif Kenano
glu
a,b
a
C¸ ukurova University, Faculty of Engineering, Department of Automotive Engineering, Turkey
b
_
Iskenderun Technical University, Faculty of Engineering, Department of Mechanical Engineering, Turkey
article info
Article history:
Received 30 November 2017
Received in revised form
28 March 2018
Accepted 4 April 2018
Available online xxx
Keywords:
Hydroxy
HHO-CNG
Performance and emissions
Pilot injection
Internal combustiosn engine
abstract
Energy security is an important consideration for development of future transport fuels.
Among the all gaseous fuels hydrogen or hydroxy (HHO) gas is considered to be one of the
clean alternative fuels. Hydrogen is very flammable gas and storing and transporting of
hydrogen gas safely is very difficult. Today, vehicles using pure hydrogen as fuel require
stations with compressed or liquefied hydrogen stocks at high pressures from hydrogen
production centres established with large investments.
Different electrode design and different electrolytes have been tested to find the best
electrode design and electrolyte for higher amount of HHO production using same electric
energy. HHO is used as an additional fuel without storage tanks in the four strokes, 4-
cylinder compression ignition engine and two-stroke, one-cylinder spark ignition engine
without any structural changes. Later, previously developed commercially available dry
cell HHO reactor used as a fuel additive to neat diesel fuel and biodiesel fuel mixtures. HHO
gas is used to hydrogenate the compressed natural gas (CNG) and different amounts of
HHO-CNG fuel mixtures are used in a pilot injection CI engine. Pure diesel fuel and diesel
fuel þbiodiesel mixtures with different volumetric flow rates are also used as pilot in-
jection fuel in the test engine. The effects of HHO enrichment on engine performance and
emissions in compression-ignition and spark-ignition engines have been examined in
detail. It is found from the experiments that plate type reactor with NaOH produced more
HHO gas with the same amount of catalyst and electric energy. All experimental results
from Gasoline and Diesel Engines show that performance and exhaust emission values
have improved with hydroxy gas addition to the fossil fuels except NO
x
exhaust emissions.
The maximum average improvements in terms of performance and emissions of the
gasoline and the diesel engine are both graphically and numerically expressed in results
and discussions. The maximum average improvements obtained for brake power, brake
torque and BSFC values of the gasoline engine were 27%, 32.4% and 16.3%, respectively.
Furthermore, maximum improvements in performance data obtained with the use of HHO
enriched biodiesel fuel mixture in diesel engine were 8.31% for brake power, 7.1% for brake
torque and 10% for BSFC.
©2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
*Corresponding author.C¸ ukurova University, Faculty of Engineering, Department of Automotive Engineering, Turkey.
E-mail address: kdraydin@cu.edu.tr (K. Aydin).
Available online at www.sciencedirect.com
ScienceDirect
journal homepage: www.elsevier.com/locate/he
international journal of hydrogen energy xxx (2018) 1e12
https://doi.org/10.1016/j.ijhydene.2018.04.026
0360-3199/©2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
Introduction
In recent years, the threat of environmental security and
global warming has been taken into account by the vast ma-
jority of scientists and numerous studies have been under-
taken to slow down or stop the adverse effects of these factors
[1e10]. Due to the depletion of fossil fuel sources and harmful
environmental effects of their utilization, sustainable energy
sources and energy carriers have become an important sub-
ject and hydrogen will have a crucial role to reduce de-
pendency of fossil fuels [11e14]. When emissions are
considered, it is known that hydrogen or hydroxy (HHO) gas is
the cleanest source of energy among all alternative fuels.
Hydroxy Gas (HHO) is formed by separating the atoms in the
water molecule by electrolysis (theoretically 67% H and 33% O)
as understood from the abbreviation [15]. Its calorific value is
extremely high with respect to diesel and gasoline. For
instance, the calorific value of 1 kg of HHO is 3 times and 3.2
times greater than gasoline and diesel fuel, respectively [16].
Dincer, I. [17], expressed that the most effective method
known for producing almost pure hydrogen is water elec-
trolysis. The electrolysis phenomena were discovered by Sir
Anthony Carlisle and William Nicholson in early 1800s. They
used a pair of conducting wires to connect electrodes of the
Volta battery and the other ends immersed separately in the
saline solution. As a result, hydrogen and oxygen have begun
to accumulate at the tip of the electrode due to the water
acting as a conductor [18]. There are three main different
types of electrolysis, such as alkaline water, solid oxide and
PEM (polymer electrolyte membrane) water electrolysis [19].
Three major issues, low partial load range, limited current
density and low operating pressure, are related with alkaline
electrolyzers. In this study, alkaline water electrolysis method
was used. SOECs (solid oxide electrolyzer cells) gain impor-
tance because while they are producing hydrogen with high
efficiency, they can convert electrical energy into chemical
energy. PEMs discovered by Grubb, and they used solid sul-
fonated polystyrene membrane as an electrolyte [20,21].Itis
known as water electrolysis by proton exchange membrane or
polymer electrolyte membrane. Besides, they called solid
polymer electrolyte (SPE) water electrolysis rarely [19].
PEMs also used as a fuel cell. Fuel cells operate with pure
hydrogen gas, natural gas and biogas fuels. The ability of fuel
cells to be used in vehicles varies according to their power
generation capacity [22]. In the USA, Fuel cells have been
studied for use with hydrocarbon fuels depending on the
operating temperature of 500e800 C[23e25]. Granovskii et al.
[26] fuel cells stacks and ion conductive membranes applica-
tions on gas turbine cycles allow increasing electricity gener-
ation efficiency and decreasing air pollution emissions.
In recent years, exhaust emissions, which play a significant
role in the hole of the ozone layer and in global warming, have
been restricted by various agreements. Because of these sit-
uations, many researchers have tended to alternative fuels in
internal combustion engines. Although many alternative fuels
have been tried by these researchers, it appears that alterna-
tive fuel with the best performance is hydrogen. Hydrogen has
many advantages over fossil fuels. The absence of carbon and
other harmful substances in the first place and the abundance
of compounds in nature are some of these. All exhaust
emissions, except nitrogen, can be regulated by using
hydrogen as a fuel. The fuel properties of hydrogen are given
in Table 1 [27].
Pure hydrogen could be used as a fuel in S.I. engine solely
with higher efficiency and higher power outputs [28]. But there
are some severe disadvantages of using hydrogen as a fuel in
S.I. engine e.g. engine knock, pre-ignition and NO
x
emission
[29]. The using of hydrogen as an alternative in C.I. engines is
defined as a new concept. Due to the high ignition tempera-
ture (858K) hydrogen cannot be ignited without any spark or
additives. The methods of hydrogen usage in CI engines are air
enrichment with hydrogen, directly injection into the intake
system and in-cylinder injection [30].
Other researchers have examined the use of hydrogen,
natural gas and their mixtures in internal combustion engines
in terms of second law analysis [31]. Rakopoulos et al. were
investigated the exergy efficiency of hydrogen and natural gas
fuel blends for direct injection CI engine. The results showed
that as the engine load increased, the irreversibility genera-
tion of the engine decreased [32].
Many studies have performed on dual fuel engines to
investigate performance and emission characteristics of
different alternative energy sources with diesel as a pilot
source of ignition. Saravanan et al. used hydrogen as a source
of energy and diesel as a source of ignition in their work. Their
results indicated that CO, CO
2
and HC values were reduced at
negligible concentrations, although engine efficiency was
increased [27]. Shitole at al. used HHO gas for the air enrich-
ment in C.I. engine by 1 lpm. Their results were indicated that
thermal efficiency, power and specific fuel consumption
values were improved however, NO
x
formation was increased
due to high flammability of hydrogen [33]. Verde and Frame
performed a research about dual fuel mode. They obtained
some improvements of performance parameters.
Kumar et al. investigated the combustion process effects of
hydrogen enrichment on single-cylinder diesel-engine using
biodiesel from vegetable oil in their study. The experimental
results showed that the brake thermal efficiency was
improved by 2% when used 7% of hydrogen by mass at
Table 1 eThe properties of hydrogen.
Properties Diesel Unleaded
gasoline
Hydrogen
Autoignition temperature (K) 530 533e733 858
Minimum ignition energy (mJ) e0.24 0.02
Flammability limits
(volume % in air)
0.7e5 1.4e7.6 4e75
Stoichiometric airefuel
ratio on mass basis
14.5 14.6 34.3
Limits of flammability
(equivalence ratio)
e0.7e3.8 0.1e7.1
Density at 16 C and
1.01 bar (kg/m
3
)
833e881 721e785 0.0838
Net heating value (MJ/kg) 42.5 43.9 119.93
Flame velocity (cm/s) 30 37e43 265e325
Quenching gap in NTP air (cm) e0.2 0.064
Diffusivity in air (cm
2
/s) e0.08 0.63
Research octane number 30 92e98 130
Motor octane number e80e90 e
international journal of hydrogen energy xxx (2018) 1e122
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
maximum power output. Smoke was reduced by 0.7 Bosch
smoke unit (BSU). Although HC and CO emissions were
reduced 130 to 100 ppm, respectively, NOx formations
increased by 19.2% [34].
Samuel and McCormick, performed their study with the
addition of hydrogen-oxygen mixture obtained by the water
electrolysis. The concentration of NO
x
in emission was
reduced to 17.9% by using 1.5 lpm of the hydrogen-oxygen
mixture. However, when the mixture supply was increased
to 2.8 lpm, NO
x
emission increases [35]. Saravanan and
Nagarajan [36] made an investigation on the hydrogen-
enriched air induction in a diesel engine. The results indi-
cated that in experiments with 30% hydrogen enrichment,
motor efficiency increased by 27.9% over the entire load range
without knocking. Also, they expressed that specific fuel
consumption values were decreased by increasing the
amount of hydrogen for all operation range.
When gas fuels are used in the mixture, the gases forming
the mixture show their properties in the mixture to the extent
they are involved [37]. Also, hydrogen can also be used as a fuel
mixture with another gaseous fuel. Naglingam et al. [38] the
hydrogen-natural gas fuel mixture has a higher burning ve-
locity compared to natural gas use alone and therefore it has
been proved that higher torque can be obtained with lower
spark advance. This burning rate can improve engine effi-
ciency nevertheless; it caused that increasing of NOx emis-
sions because of higher temperatures obtained during
combustion [39e42]. Arat et al. [43] performed their experi-
ment with a conventional compression ignition engine with
HHO-CNG fuel mixture enrichment without any structural
changing on the test engine. They obtained significant outputs
about performance and emission values. All performance data
in their study, power, torque and BSFC, were improved by
using HHOCNG enriched diesel fuel with the rate of 4.7%, 6.75%
and 17.2%, respectively. Also, related studies in the literature
are matching with these improvements values [35,43e49].
Hydroxy gas is used with biodiesel, which is another
alternative energy source, for enrichment [50e52]. Baltacioglu
at al [37]. conducted their experiments with HHO enriched
sunflower biodiesel. The main purpose of the experiments is
to compare performance and emission characteristics of pure
hydrogen and HHO enriched biodiesel fuels in a pilot injection
diesel engine. The amount of hydrogen fuel given to the test
engine during the experiments was set at 10 L/min. The re-
sults will be discussed in the results and discussion section.
Fig. 1 ePlate type (a), Cylindrical type (b) and Wire type (c) electrodes used in this study.
Fig. 2 eCommercial HHO reactor system.
Table 2 eTest engine specifications.
Brand Mitsubishi
Model 4D32 - In line 4
Displacement 3567 cc
Bore Stroke 104 mm 105 mm
Max. Power 89 kW (at 3200 rpm)
Max. Torque 295 Nm (at 1800 rpm)
Fig. 3 eMixing chamber of gaseous fuels.
international journal of hydrogen energy xxx (2018) 1e12 3
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
Fig. 4 eGeneral view of second part of experimental setup.
(a) (b)
(c) (d)
0
1
2
3
4
5
6
7
00.511.52
Production of HHO (L/min)
MASS FRACTION,%
Plate Reactor
NaOH NaCl KOH
0
1
2
3
4
5
6
7
00.511.52
Production of HHO (L/min)
MASS FRACTION,%
NaOH NaCl KOH
Cylindrical Reactor
0
1
2
3
4
5
6
7
00.511.52
Production of HHO (L/min)
MASS FRACTION,%
NaOH NaCl KOH
Wire Reactor
0
1
2
3
4
5
6
7
0 0.5 1 1.5 2
Production of HHO (L/min)
MASS FRACTION,%
Comparison of Different Reactor with NaOH
Plate Reactor
Cylindrical Reactor
Wire Reactor
Fig. 5 eDifference of HHO flow rates using Plate (a), Cylindrical (b) and Wire (c) type reactors with catalyst mass fraction and
comparison of different reactors HHO production with NaOH catalyst (d).
international journal of hydrogen energy xxx (2018) 1e124
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
Material and method
This experimental study which is composed of the perfor-
mance and emission characteristics of HHO gas fuel used as
fuel enrichment in internal combustion engines and HHO
production is investigated into two parts.
In the beginning of the first part, HHO is produced by
electrolytes of KOH, NaOH and NaCl with plate, cylindrical
and wire type electrodes in a leak-proof Plexiglas reactor.
Firstly, the HHO, which is used in diesel and gasoline en-
gines, is sent to the intake manifold after passing through a
security tank to prevent backfire after production. The sensors
are placed in the production container to monitor the increase
in temperature and pressure during HHO production. The
pressure increment of the container was regulated and pro-
tected by using the non-turn valve. To observe the probable
hydrogen leakage an electronic hydrogen leak detector is used
(see Fig. 1).
In the second part of experimental study is also explained
by figures in detail. The commercially available dry cells were
used to produce HHO as it is given in Fig. 2. As seen from the
figure, The HHO system consists of a solution tank, a filter, and
a led display showing the current to the plate during elec-
trolysis. These dry cells have 14 plates and they connected in
parallel each other.
Fuel pump plunger of the test engine is modified to run
pilot injection mode to ignite CNG without adding ignition
Fig. 6 eThe schematic diagram of the HECU and The photograph of HECU.
0
2
4
6
8
10
0 1000 2 000 3000 4000 5000 6000
Torque (Nm)
Engine Speed (rpm)
Gasoline Gas+HHO+HECU
Fig. 7 eVariation of brake torque with engine speed.
900
1100
1300
1500
1700
1900
0 1000 2000 3000 4000 5000 6000
SFC (g/kWh)
Engine Speed (rpm)
Gasoline Gas+HHO+HECU Gasoline Gas+HHO+HECU
Fig. 8 eVariation of SFC with engine speed.
international journal of hydrogen energy xxx (2018) 1e12 5
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
system and spark plug into the engine cylinders. The amount
of liquid fuel injected into the cylinders is reduced by 15%e
30% via fuel pump plunger.
In this experimental study, the gaseous fuels used as
substitute fuels were mixed at certain ratios before they were
taken into the cylinder. CNG gas is mixed up with 15%, 25%
and 35% (by volumes) hydrogen and HHO in the mixing
chamber before entering to the intake manifold of the test
engine as shown below in Fig. 3. Performance and emissions
tests were performed with different amount of liquid fuels
(diesel fuel and biodiesel) and hydrogenation ratios of CNG.
A water cooled, 3.6 L, four stroke, direct injection
compression ignition engine, the main component of this
study, was used in all tests. The specifications of this engine
are given in Table 2. A hydraulic dynamometer was used to
apply the required load during the tests. The MRU Delta 1600 V
gas analyzer was used to determine the effect of fuels on
exhaust emissions, to determine the extent of exhaust
6500
7000
7500
8000
8500
9000
0 1000 2000 3000 4000 5000 6000
HC (ppm)
Engine Speed (rpm)
Gasoline Gas+HHO+HECU Gasoline Gas+HHO+HECU
Fig. 9 eHC Emissions vs. engine speed.
0
2
4
6
8
10
0 1000 2000 3000 4000 5000 6000
CO (vol%)
Engine Speed (rpm)
Gasoline Gas+HHO+HECU Gasoline Gas+HHO+HECU
Fig. 10 eVariation of CO Emissions with engine speed.
Fig. 11 eVariation of Brake Torque with engine speed.
800
1000
1200
1400
1600
1800
1000 1500 2000 2500 3000
SFC (g/kWh)
Engine Speed (rpm)
Diesel+HHO+HECU Diesel Diesel+HHO+HECU Diesel
Fig. 12 eVariation of SFC with engine speed.
international journal of hydrogen energy xxx (2018) 1e126
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
emissions. Data logger was used to collect performance out-
puts of dynamometer, sensors, flowmeters and exhaust gas
outputs of gas analyzer. The whole experimental setup is
presented in Fig. 4 schematically.
Results and discussion
This study was formed as two parts. The first one is about HHO
production by using different electrolyte types and different
3
4
5
6
7
8
9
1000 1500 2000 2500 3000
CO (vol %)
Engine Speed (rpm)
Diesel+HHO+HECU Diesel Diesel+HHO+HECU Diesel
Fig. 14 eCO Emissions vs. Engine speed.
7000
7300
7600
7900
8200
8500
1000 1500 2000 2500 3000
HC (ppm)
Engine Speed (rpm)
Diesel+HHO+HECU Diesel Diesel+HHO+HECU Diesel
Fig. 13 eHC Emissions vs Engine speed.
Fig. 15 ePerformance values, Brake Power (a), Brake Torque (b) and BSFC (c) vs. Engine Speed.
international journal of hydrogen energy xxx (2018) 1e12 7
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
catalytic and its performance and emission analysis in both
spark ignition (SI) and compression ignition (CI) engines.
Other part of this section consists of the performance and
emission analysis by using different hydrogenation ratio of
CNG.
Comparison of different types of reactor and catalyst on
HHO production
In the first part of this experimental study, it is found from
the experiments that plate type reactor with NaOH pro-
duced more HHO gas with the same amount of catalyst and
electric energy. Similarly KOH is another alternative catalyst
because of hydrogen and oxygen contents of NaOH pro-
duces more HHO gas against NaCl. Manufacturing of plate
type reactor is easier and cheaper than other types of re-
actors, therefore plate type dry cell HHO reactor is devel-
oped for commercial manufacturing. The HHO production
characteristics of all types of reactors were obviously given
in Fig. 5 [53].
Additionally in Fig. 5, different reactors used during the
experiments with NaOH catalyst, which provides the best
HHO production among all catalyst types, were compared in
terms of HHO production rate.
Performance and Emission Results of HHO Enrichment with
HECU in Internal Combustion Engines
It was observed from experiments, the flow rate should be
decreased due to adverse effects of hydrogen on volumetric
efficiency [55] when the engine speed reached under the
critical values, which are 2500 rpm and 1750 rpm, for CI and SI
engines, respectively. However, an electronic control unit
connected to the HHO system was designed and coupled to
the system in order to avoid the decrease in volumetric effi-
ciency. This control unit was designed and manufactured to
regulate HHO production by reducing the voltage and current
supplied to the system as seen from Fig. 6 [53].
The experimental results with HHO þHECU (Hydroxy gas
Electronic Control Unit) were investigated in detail in internal
combustion engine. In this experimental study with HECU,
gasoline (SI) and diesel (CI) engines were used for tests. Firstly,
the SI engine results were given by graphs. It is obviously seen
from Fig. 7, engine torque was improved by 32.4% an average by
using HHO þHECU, and the engine power was also increased
27% with respect to pure gasoline operation. The extra oxygen
in the HHO and the HHO - air mixture in the cylinders caused
the fuel to burn better, thus enhancing the engine power.
It is also see that from Fig. 8, an average improvement is
16.3% for Brake Specific Fuel Consumption (SFC) by using HHO
system. The reduction in SFC is due to the fact that the extra
Fig. 16 eEmission values, CO
2
(a), CO (b) and NO
x
(c) vs. Engine Speed.
international journal of hydrogen energy xxx (2018) 1e128
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
oxygen present in the HHO gas enhances the combustion ef-
ficiency and the HHO provided more homogeneous mixture
with air, because of its high diffusivity.
Similiar improvements were measured for emission
values. As can be seen in Fig. 9, HC emissions were reduced by
6.7% on average compared to pure gasoline operating condi-
tions. The oxygen in the HHO plays an effective role in
reducing the HC emissions that are evolved by improving the
combustion. At low speeds, however, HHO reduces the volu-
metric efficiency and therefore does not get enough air to burn
the cylinders and causes increased HC emissions.
When compared to pure gasoline oparation, CO emis-
sions were reduced 14.4% by using HHO as shown in Fig. 10.
The major reason of this reduction is the carbon free HHO
addition to the cylinder. It appears that CO emissions were
rising while approaching low speeds. If the HHO flow is not
regulated according to the engine speed, the increasing of
the CO will continue to appear as the engine speed
decreases.
The experimental results with CI engine have shown that
the performance of HHO improves performance and emis-
sions even though it shows different characteristics with
gasoline engine tests. It is seen from Fig. 11, the engine torque
was increased by using HHO system an average of 19.1%
compared to standard diesel operation. The engine power was
also increased 27% with respect to standard diesel operation
because of the extra oxygen concentration of HHO and better
combustion.
Also similar improvements were obtained for specific fuel
consumption. An average improvement of 14% was obtained
by using HHO system. It has also shown as Fig. 12. The
reduction in SFC is thanks to the extra oxygen present in the
HHO gas and because of high diffusivity of the HHO provided
more homogeneous mixture with air, enhanced the combus-
tion efficiency.
It is seen that from Fig. 13, HC emissions were reduced in
average 5% at above the engine speed of 1750 rpm. Because of
both the opening time of the valves was short and the
hydrogen covered high volume, sufficient air can not be taken
into the cylinders at high revs. As a result, combustion effi-
ciency was reduced by inadequate combustion.
The last figure of the first part is given below as Fig. 14.CO
emissions were reduced in average 13.5% at higher engine
speeds than 1750 rpm. The major reason of this reduction is
the carbon free HHO addition to the cylinder.
Performance and Emission Results of hydrogen and HHO
enriched biofuels
The second part of this study was composed of performance
and emission analysis and comparison of HHO and H
2
usage
as a fuel enrichment with different ratios in compression
ignition engine. The performance and emisisons results
were given by graphs. The brake power results was shown in
Fig. 15(a), an average improvement of 10 L/min HHO
Fig. 17 ePerformance values, Brake Torque (a), Brake Power (b) and BSFC (c) vs. Engine Speed for qpd operations.
international journal of hydrogen energy xxx (2018) 1e12 9
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
enrichment of B10 fuel was 8,31% according to neat diesel
fuel.
It is well known criteria that; hydrogen shows spectacular
combustion characteristics like flame speed and higher
heating value during combustion compared to liquid fuels.
So, brake torque outputs were improved in all cases of this
study by using hydrogen and HHO enriched fuels according
to neat diesel fuel and B10. The torque results were given by
graph 15(b).
Hydrogen is one of the most impressive alternative fuels in
terms of heating value. Although the heating value of the
biodiesel is lower than the standard diesel, the hydrogen-
enriched biodiesel fuel also reduced specific fuel consump-
tion due to its high performance outputs. The decrement of
H
2
þB10 was 2% as well as HHO þB10 fuel provided 10% in
average as seen from Fig. 15(c).
When considering the emission values, CO
2
emission
values were reduced with hydrogen-enriched biodiesel fuel at
low engine speeds (between 1200 and 1800 rpm) compared to
greater than these interval as seen from Fig. 16(a). The im-
provements of emission values 2% and 10% in average for
B10 þH
2
and B10 þHHO, respectively.
The almost similar characteristics were observed for the
use of B10 þH
2
and B10 þHHO in terms of CO emissions.
Although both fuels achieved decreasing of CO however, there
was a different between CO gas emissions outputs of H
2
þB10
fuel and the HHO þB10 fuel. Better reduction of CO emission
was obtained with B10 þH
2
fuel compared to the B10 þHHO
by 5.8% in average. Compared to standard diesel operation,
B10 þH
2
fuel provides maximum improvement with 38%
reduction in 2300 rpm. as shown in Fig. 16(b). NOx formation
was increased with B10 þH
2
and B10 þHHO due to use of
hydrogen as a fuel enrichment during combustion. NO
x
emissions were increased 20% and 16% in average by using
HHO þB10 and H
2
þB10 fuels, respectively. The results were
given in Fig. 16(c).
Another experimental results of this study are about
gaseous fuel enrichments with diesel or biodiesel pilot
injectioninCIengine[54]. All performance datas were
given by graphs. HHOCNG additives improved the torque
values compared the CNG þqpd (quarter pilot diesel in-
jection) and neat diesel operation. It is seen from the
Fig. 17(a), HHO provides better performance output by
improving the combustion efficiency with its extra oxygen
content. The average improvement of brake torque values
were 0.78%, 4.78% and 1.02% for 20, 25 and 30 HHOCNG
respectively.
The brake power values showed similar characteristics
with brake torque values. Average brake power improvements
were 0.88%, 4.4% and 1.3% for 20, 25 and 30 HHOCNG respec-
tively, as seen from Fig. 17(b). The use of HHO provides better
performance output by improving the combustion efficiency
with its extra oxygen content.
As it is evidently seen from Fig. 17(c), CNG and HHOCNG
mixtures were decreased the BSFC with 19.2%, 18.3%, 16.3%,
15.1% for CNG, 20, 25 and 30 HHOCNG respectively. The major
Fig. 18 ePerformance values, Brake Torque (a), Brake Power (b) and BSFC (c) vs. Engine Speed for spd operations.
international journal of hydrogen energy xxx (2018) 1e1210
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
reasons for these reductions are the use of gaseous fuel
instead of diesel fuel and the lower density of the gaseous
fuels than diesel fuels. And also, the hydrogens of HHO cause
to increase combustion temperature and pressure.
It is obviously seen that; HHO provides better performance
output by improving the combustion efficiency with its extra
oxygen content. Fig. 18(a) represents the improvements of
brake torque values were 0.8%, 4.4% and 1.2% for 20, 25 and 30
HHOCNG respectively, for semi pilot diesel injection (spd)
operations.
The brake power values showed similar characteristics
with brake torque values. Brake power graph is given as
Fig. 18(b); average brake power improvements were 1.18%,
3.15% and 1.09% for 20, 25 and 30 HHOCNG respectively.
It is obviously CNG and HHOCNG mixtures were improved
the BSFC with 26.2%, 22.3%, 20.3%, 19.1% for CNG, 20, 25 and 30
HHOCNG respectively. The BSFC results is shown from
Fig. 18(c). As the same manner with qpd operations, the major
reasons for these reductions are the use of gaseous fuel
instead of diesel fuel and the lower density of the gaseous
fuels than diesel fuels. And also, the hydrogens atoms of HHO
cause to increase combustion temperature and pressure.
Conclusion
The conclusions from the first part, HHO usage with HECU, of
this experimental study are summarized as follows:
1) The most efficient combination was determined as The
plate type electrode with NaOH-water solution for the
production of HHO. The increment of the mass fraction of
catalyst in the water directly increases the HHO flow rate.
However, when the NaOH solution in solution exceeds 1%
of the mass, the system rises to an excessive degree.
2) When the HHO system used as enrichment of diesel fuel or
gasoline, engine torque output increases at mid and higher
engine speeds according to diesel and gasoline fuelled
engine operation without HECU. HECU has to be used to
regulate the voltage and current of the HHO production by
using electrolysis at low engine speed.
3) HHO gas gives the better performance and emission char-
acteristics because of its combustion specifications, such
as extra oxygen, high burning velocity, and carbon-free
content.
The conclusions from the second part, HHO enriched bio-
fuels usage, of this experimental study are summarized as
follows:
1) All performance and exhaust emissions values have
improved with hydrogenation of HHO and H
2
except NO
x
exhaust emissions.
2) When considering the application cost and safety, HHO
fuel enrichment system is more preferable in diesel
engines.
3) This study shows the availability of using HHOCNG mix-
tures as an indicator alternative fuel in diesel engines
applications.
4) Both quarter and semi-pilot diesel injections improved the
fuel economy perspective and reduced the specific fuel
consumptions.
5) 25 HHOCNG fuel mixture with semi-pilot injection opera-
tion was obtained the best mix when used as an alternative
and additional fuel for run under this test engine.
references
[1] Kanoglu M, Dincer I, Cengel YA. Exergy for better
environment and sustainability. Environ Dev Sustain
2009;11(5):971e88.
[2] Mintz M, Han J, Burnham A. Alternative and renewable
gaseous fuels to improve vehicle environmental
performance. In: Alternative fuels and advanced vehicle
technologies for improved environmental performance;
2014. p. 90e116.
[3] Wang J, Huang Z, Fang Y, Liu B, Zeng K, Miao H, et al.
Combustion behaviors of a direct-injection engine operating
on various fractions of natural gasehydrogen blends. Int J
Hydrogen Energy 2007;32(15):3555e64.
[4] Korakianitis T, Namasivayam AM, Crookes RJ. Diesel and
rapeseed methyl ester (RME) pilot fuels for hydrogen and
natural gas dual-fuel combustion in compressioneignition
engines. Fuel 2011;90(7):2384e95.
[5] Klell M, Eichlseder H, Sartory M. Mixtures of hydrogen and
methane in the internal combustion engineeSynergies,
potential and regulations. Int J Hydrogen Energy
2012;37(15):11531e40.
[6] Soberanis ME, Fernandez AM. A review on the technical
adaptations for internal combustion engines to operate with
gas/hydrogen mixtures. Int J Hydrogen Energy
2010;35(21):12134e40.
[7] Lounici MS, Boussadi A, Loubar K, Tazerout M. Experimental
investigation on NG dual fuel engine improvement by
hydrogen enrichment. Int J Hydrogen Energy
2014;39(36):21297e306.
[8] Pichayapat K, Sukchai S, Thongsan S, Pongtornkulpanich A.
Emission characteristics of using HCNG in the internal
combustion engine with minimum pilot diesel injection for
greater fuel economy. Int J Hydrogen Energy
2014;39(23):12182e6.
[9] Lilik GK, Zhang H, Herreros JM, Haworth DC, Boehman AL.
Hydrogen assisted diesel combustion. Int J Hydrogen Energy
2010;35(9):4382e98.
[10] Liew C, Li H, Nuszkowski J, Liu S, Gatts T, Atkinson R, et al.
An experimental investigation of the combustion process of
a heavy-duty diesel engine enriched with H 2. Int J Hydrogen
Energy 2010;35(20):11357e65.
[11] Midilli A, Dincer I. Hydrogen as a renewable and sustainable
solution in reducing global fossil fuel consumption. Int J
Hydrogen Energy 2008;33(16):4209e22.
[12] Do Sacramento EM, De Lima LC, Oliveira CJ, Veziroglu TN. A
hydrogen energy system and prospects for reducing
emissions of fossil fuels pollutants in the Cear
a state-Brazil.
Int J Hydrogen Energy 2008;33(9):2132e7.
[13] Kanoglu M, Dincer I, Rosen MA. Geothermal energy use in
hydrogen liquefaction. Int J Hydrogen Energy
2007;32(17):4250e7.
[14] Scott DS, Alexander N. The hydrogen defense against climate
catastrophe. In: New nuclear frontiers 30th annual Canadian
Nuclear Society conference and 33rd CNS/CNA student
conference; 2009. p. 275.
[15] Santilli RM. A new gaseous and combustible form of water.
Int J Hydrogen Energy 2006;31(9):1113e28.
international journal of hydrogen energy xxx (2018) 1e12 11
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
[16] Yilmaz AC, Uludamar E, Aydin K. Effect of hydroxy (HHO) gas
addition on performance and exhaust emissions in
compression ignition engines. Int J Hydrogen Energy
2010;35(20):11366e72.
[17] Dincer I. Green methods for hydrogen production. Int J
Hydrogen Energy 2012;37(2):1954e71.
[18] Faraday M, Schoenbein CF, Sch
onbein CF, Sch
onbein CF,
Chemist G. The letters of faraday and schoenbein 1836-1862.
Benno Schwabe; 1899.
[19] Carmo M, Fritz DL, Mergel J, Stolten D. A comprehensive
review on PEM water electrolysis. Int J Hydrogen Energy
2013;38(12):4901e34.
[20] Grubb WT. Ionic migration in ion-exchange membranes. J
Phys Chem 1959;63(1):55e8.
[21] Grubb WT. Batteries with solid ion exchange electrolytes I.
secondary cells employing metal electrodes. J Electrochem
Soc 1959;106(4):275e8.
[22] Gurz M, Baltacioglu E, Hames Y, Kaya K. The meeting of
hydrogen and automotive: a review. Int J Hydrogen Energy
2017;42(36):23334e46.
[23] Dutta S. A review on production, storage of hydrogen and its
utilization as an energy resource. J Ind Eng Chem
2014;20(4):1148e56.
[24] Raza R, Akram N, Javed MS, Rafique A, Ullah K, Ali A,
Ahmed R. Fuel cell technology for sustainable development
in PakistaneAn over-view. Renew Sustain Energy Rev
2016;53:450e61.
[25] Ahmed S, Krumpelt M. Hydrogen from hydrocarbon fuels for
fuel cells. Int J Hydrogen Energy 2001;26(4):291e301.
[26] Granovskii M, Dincer I, Rosen MA. Economic and
environmental comparison of conventional, hybrid, electric
and hydrogen fuel cell vehicles. J Power Sources
2006;159(2):1186e93.
[27] Saravanan N, Nagarajan G, Dhanasekaran C, Kalaiselvan KM.
Experimental investigation of hydrogen port fuel injection in
DI diesel engine. Int J Hydrogen Energy 2007;32(16):4071e80.
[28] Naber JD, Siebers DL. Hydrogen combustion under diesel
engine conditions. Int J Hydrogen Energy 1998;23(5):363e71.
[29] Lee JT, Kim YY, Lee CW, Caton JA. An investigation of a cause
of backfire and its control due to crevice volumes in a
hydrogen fueled engine. J Eng Gas Turbines Power
2001;123(1):204e10.
[30] Ravi M, Rao AN, Ramaswamy MC, Jagadeesan TR.
Experimental investigation on dual fuel operation of
hydrogen in a CI engine. In: Proceedings of the national
conference on IC engines and combustion, Indian institute of
petroleum, September; 1992, September. p. 15e8.
[31] Baltacıo
glu MK, Arat HT, Kenano
glu R. Exergy and
performance analysis of a CI engine fuelled with HCNG
gaseous fuel enriched biodiesel. Int J Exergy 2017;24(1):39e56.
[32] Rakopoulos CD, Scott MA, Kyritsis DC, Giakoumis EG.
Availability analysis of hydrogen/natural gas blends
combustion in internal combustion engines. Energy
2008;33(2):248e55.
[33] Shitole RR, Magdum SS, Raut NS, Mane S, Borade PB.
Performance of hydroxy gas on diesel engine. 2017.
[34] Kumar MS, Ramesh A, Nagalingam B. Use of hydrogen to
enhance the performance of a vegetable oil fuelled
compression ignition engine. Int J Hydrogen Energy
2003;28(10):1143e54.
[35] Samuel S, McCormick G. Hydrogen enriched diesel
combustion (No. 2010-01-2190). SAE Technical Paper; 2010.
[36] Saravanan N, Nagarajan G. An experimental investigation of
hydrogen-enriched air induction in a diesel engine system.
Int J Hydrogen Energy 2008;33(6):1769e75.
[37] Baltacioglu MK, Arat HT,
Ozcanli M, Aydin K. Experimental
comparison of pure hydrogen and HHO (hydroxy) enriched
biodiesel (B10) fuel in a commercial diesel engine. Int J
Hydrogen Energy 2016;41(19):8347e53.
[38] Nagalingam B, Duebel F, Schmillen K. Performance study
using natural gas, hydrogen-supplemented natural gas and
hydrogen in AVL research engine. Int J Hydrogen Energy
1983;8(9):715e20.
[39] Mariani A, Prati MV, Unich A, Morrone B. Combustion
analysis of a spark ignition ic engine fuelled alternatively
with natural gas and hydrogen-natural gas blends. Int J
Hydrogen Energy 2013;38(3):1616e23.
[40] Ma F, Wang Y, Liu H, Li Y, Wang J, Zhao S. Experimental
study on thermal efficiency and emission characteristics of a
lean burn hydrogen enriched natural gas engine. Int J
Hydrogen Energy 2007;32(18):5067e75.
[41] Genovese A, Contrisciani N, Ortenzi F, Cazzola V. On road
experimental tests of hydrogen/natural gas blends on transit
buses. Int J Hydrogen Energy 2011;36(2):1775e83.
[42] Mariani A, Morrone B, Unich A. Numerical evaluation of
internal combustion spark ignition engines performance
fuelled with hydrogeneNatural gas blends. Int J Hydrogen
Energy 2012;37(3):2644e54.
[43] Arat HT, Baltacioglu MK,
Ozcanli M, Aydin K. Effect of using
HydroxyeCNG fuel mixtures in a non-modified diesel engine
by substitution of diesel fuel. Int J Hydrogen Energy
2016;41(19):8354e63.
[44] Al-Rousan AA. Reduction of fuel consumption in gasoline
engines by introducing HHO gas into intake manifold. Int J
Hydrogen Energy 2010;35(23):12930e5.
[45] Le Anh T, Duc KN, Thu HTT, Van TC. Improving performance
and reducing pollution emissions of a carburetor gasoline
engine by adding HHO gas into the intake manifold (No.
2013-01-0104). SAE Technical Paper; 2013.
[46] Zammit G, Farrugia M, Ghirlando R. Experimental
investigation of the effects of hydrogen enhanced
combustion in SI and CI engines on performance and
emissions. In: 9th international conference on heat transfer,
fluid mechanics and thermodynamics (HEFAT); 2012.
p. 641e50.
[47] Karim GA, Wierzba I, Al-Alousi Y. Methane-hydrogen
mixtures as fuels. Int J Hydrogen Energy 1996;21(7):625e31.
[48] Patil KR, Khanwalkar PM, Thipse SS, Kavathekar KP,
Rairikar SD. Development of HCNG blended fuel engine with
control of NOx emissions. In: In emerging trends in
engineering and technology (ICETET); 2009. p. 1068e74.
[49] Arat HT, Baltacio
glu MK,
Ozcanli M, Aydın K. Optimizing the
quantity of diesel fuel injection by using 25HHOCNG gas fuel
mixture. In: Advanced engineering forum, vol. 14. Trans
Tech Publications; 2016. p. 36e45.
[50] Baltacıo
glu MK. Hydroxy (HHO) and hydrogen (H
2
) enriched
compressed natural gas (CNG) usage in biodiesel fueled
compression ignition (CI) engines [PhD Thesis]. Cukurova
University; 2016.
[51] Ozcanli M, Akar MA, Calik A, Serin H. Using HHO (Hydroxy)
and hydrogen enriched castor oil biodiesel in compression
ignition engine. Int J Hydrogen Energy 2017;42(36):23366e72.
[52] Kale KA, Dahake MR. The effect of HHO and biodiesel blends
on performance and emission of diesel engine-a review.
2016.
[53] Yilmaz AC. Design and applications of hydroxy (HHO)
system [M. Sc. Thesis]. Cukurova University; 2010.
[54] Arat HT. Experimental investigation of hydroxy gas enriched
natural gas as an alternative fuel (HHO-CNG) in pilot
injection diesel engines [PhD Thesis]. Cukurova University;
2016.
[55] Zamfirescu C, Dincer I. Ammonia as a green fuel and
hydrogen source for vehicular applications. Fuel Process
Technol 2009;90(5):729e37.
international journal of hydrogen energy xxx (2018) 1e1212
Please cite this article in press as: Aydin K, Kenano
glu R, Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on
performance and emissions of internal combustion engines, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/
j.ijhydene.2018.04.026
... Several researchers used HHO gas as an alternate energy source blended with air and diesel/gasoline fuel to boost engine performance while lowering the danger of harmful gas emissions [66][67][68][69][70][71]. Gad et al., [66] recently studied the impact of HHO gas on diesel engine performance and emissions. ...
... When using HHO gas as a fuel additive, CO and HC concentrations in exhaust gases were lowered in the majority of cases; NOx concentrations were reduced in SI engines but increased in diesel engines. Aydin and Kenanoglu [70] investigated the performance of four-stroke, two-stroke, and single-stroke engines after introducing various designs of commercially available HHO fuel cells without a storage tank. Their findings show a significant improvement in brake power, brake torque, and brake-specific fuel consumption of gasoline engines of up to 27%, 32.4% and 16.3%, respectively. ...
Article
The excessive use of fossil fuels and the resultant dramatic increase in pollution levels have highlighted the need for a new sustainable and environmentally friendly fuel. Hence, it is necessary to research alternatives to reduce the use of fossil fuels and the emission of greenhouse gases. Utilising oxyhydrogen (HHO) gas has been proven to achieve high engine power output and efficiency with low emissions for spark-ignited internal combustion engines. HHO gas is generated from the electrolysis of water. This paper reviews the recent research findings related to the influencing factors on the production of HHO gas using alkaline water electrolysis involving electrolyte properties, electrolyte concentration, the distance between electrolytes, and the effects of HHO gas on the engine performance and gas emissions. Using an HHO gas blend in a diesel/gasoline engine could be a viable option for lowering GHG emissions and increasing engine efficiency.
... [137]. Due to these constraints, combining natural gas with hydrogen for use in an internal combustion engine is an effective way to increase burn velocity, with hydrogen having a laminar burning velocity of 2.9 m/s against 0.38 m/s for methane [138]. Additionally, the inclusion of hydrogen can improve fuel economy and thermal efficiency. ...
Full-text available
Article
Nowadays, the combustion of fossil fuels for transportation has a major negative impact on the environment. All nations are concerned with environmental safety and the regulation of pollution, motivating researchers across the world to find an alternate transportation fuel. The transition of the transportation sector towards sustainability for environmental safety can be achieved by the manifestation and commercialization of clean hydrogen fuel. Hydrogen fuel for sustainable mobility has its own effectiveness in terms of its generation and refueling processes. As the fuel requirement of vehicles cannot be anticipated because it depends on its utilization, choosing hydrogen refueling and onboard generation can be a point of major concern. This review article describes the present status of hydrogen fuel utilization with a particular focus on the transportation industry. The advantages of onboard hydrogen generation and refueling hydrogen for internal combustion are discussed. In terms of performance, affordability, and lifetime, onboard hydrogen-generating subsystems must compete with what automobile manufacturers and consumers have seen in modern vehicles to date. In internal combustion engines, hydrogen has various benefits in terms of combustive properties, but it needs a careful engine design to avoid anomalous combustion, which is a major difficulty with hydrogen engines. Automobile makers and buyers will not invest in fuel cell technology until the technologies that make up the various components of a fuel cell automobile have advanced to acceptable levels of cost, performance, reliability, durability, and safety. Above all, a substantial advancement in the fuel cell stack is required.
... Fossil fuels, such as petroleum, natural gas, and coal, play a significant role in the world's energy supply, which exacerbates the depletion of hydrocarbon fuel resources [1]. The combustion of the fossil fuels can produce various gases, including carbon oxides, surfer oxides and nitrogen oxides, which may cause global environmental problems [2,3]. ...
Full-text available
Article
Hydrogen is considered to be a very efficient and clean fuel since it is a renewable and non-polluting gas with a high energy density; thus, it has drawn much attention as an alternative fuel, in order to alleviate the issue of global warming caused by the excess use of fossil fuels. In this work, a novel Cu/ZnS/COF composite photocatalyst with a core-shell structure was synthesized for photocatalytic hydrogen production via water splitting. The Cu/ZnS/COF microspheres formed by Cu/ZnS crystal aggregation were covered by a microporous thin-film COF with a porous network structure, where COF was also modified by the dual-effective redox sites of C=O and N=N. The photocatalytic hydrogen production results showed that the hydrogen production rate reached 278.4 µmol g−1 h−1, which may be attributed to its special structure, which has a large number of active sites, a more negative conduction band than the reduction of H+ to H2, and the ability to inhibit the recombination of electron-hole pairs. Finally, a possible mechanism was proposed to effectively explain the improved photocatalytic performance of the photocatalytic system. The present work provides a new concept, in order to construct a highly efficient hydrogen production catalyst and broaden the applications of ZnS-based materials.
Article
There is rising interest globally in the use of hydrogen for the provision of electricity or heat to industry, transport, and other applications in low-carbon energy systems. While there is attention to build out dedicated hydrogen infrastructure in the long-term, blending hydrogen into the existing natural gas pipeline network is also thought to be a promising strategy for incorporating hydrogen in the near-term. However, hydrogen injection into the existing gas grid poses additional challenges and considerations related to the ability of current gas infrastructure to operate with blended hydrogen levels. This review paper focuses on analyzing the current understanding of how much hydrogen can be integrated into the gas grid from an operational perspective and identifies areas where more research is needed. The review discusses the technical limits in hydrogen blending for both transmission and distribution networks; facilities in both systems are analyzed with respect to critical operational parameters, such as decrease in energy density, increased flow speed and pressure losses. Safety related challenges such as, embrittlement, leakage and combustion are also discussed. The review also summarizes current regulatory limits to hydrogen blending in different countries, including ongoing or proposed pilot hydrogen blending projects.
Article
In our previous work, we found that hydrogen permeation can be noticeably reduced during Ni–Cu electroplating by the addition of Ce salt to the plating solution. The mechanism of hydrogen permeation inhibition via Ce salt was further studied in the present work. Through the Iver–Pickering–Zamenzadeh (IPZ) model fitting of the kinetic of hydrogen evolution reaction, we found that the trace Ce salt that precipitated during electroplating could improve Tafel reaction kinetic parameters and reduce the strength of the Ni–H and Cu–H bonds due to its abundant d/f electrons and enough d/f orbitals. Meanwhile, Ce can provide electrons for the Heyrovsky reaction. These effects promoted surface electron migration and thus led to the desorption of adsorbed hydrogen atoms (Hads) and the decreased diffusion of Hads into the Ni–Cu coatings. The accuracy of the IPZ model fitting results was verified by hydrogen evolution rate experiments during the electroplating process. Hence, Ce salt can effectively inhibit hydrogen permeation and reduce the dehydrogenation annealing time, thereby showing great potential for energy saving and emission reduction in the electroplating industry.
Article
Blending oxy-hydrogen (HHO gas) with gasoline is promising to reduce emissions and improve engine performance. In this scenario, this study conducts several experiments on different configurations to produce the highest HHO gas yield mixed with gasoline and tested at different engine speeds. The design 8C8A4N is chosen due to its high HHO gas output, low current consumption, and low electrolyte concentration. At an electric current of 15 and 28 A, the dry cell of 20 plates could yield 250 – 500 mL min−1. The specific fuel consumption, output power, torque, air–fuel ratio, air–fuel equivalence ratio, NOX, HC, CO, and CO2 emissions were measured and discussed. A comparative study of performance and emissions is conducted to demonstrate the impact of HHO on light vehicles. The maximum improvements in brake power and brake torque relative to gasoline at engine speeds from 3500 to 5300 rpm are measured to be 16.52 and 12.89%, respectively, at an HHO gas flow rate of 0.5 L min−1. In comparison to pure gasoline at the engine speed range, the highest reductions in specific fuel consumption, CO, CO2, NOx, and HC emissions are 39.92, 33.86, 26.42, 19.43, and 26%, respectively. Therefore, the HHO blended gasoline is promising for both thermal performance and economic impacts.
Full-text available
Article
This article provides a critical assessment of H2 from the standpoint of more widespread use as a sustainable fuel for Indian mobility applications in the global context. The potential techno-economic advantages of utilizing H2 for automobiles rather than battery electric vehicles or conventional internal combustion engine vehicles are emphasized. The present assessment demonstrates that H2 production, storage, and distribution costs are the primary challenges, and a significant improvement is still necessary for H2 to compete either against the internal combustion engine vehicle or the battery electric vehicle to win the race, arguably. The secondary challenges have also been demonstrated, which include the cost of the fuel cell stack and the modifications associated with internal combustion engine vehicles, as well as regulatory and safety concerns, which impede the widespread usage of H2. It is critical that policy-making for sustainable mobility in India is possible with the aid of a National H2 Energy Road Map This in turn can achieve a cost target of $0.5/kg for H2.
Chapter
Early Direct Injection Homogenous Charge Compression Ignition (HCCI) helps in the reduction of NOx and smoke emissions. However, this strategy gives out higher carbon monoxide and hydrocarbon emissions with less power and fuel economy. To address this issue, experiments were carried out to investigate the effect of addition of oxy-hydrogen (HHO) gas in compression ignition engine with injection advance. The fuel injection timing and pressure were set to 45 bTDC and 600 bar, respectively. The production of HHO gas was done by the electrochemical splitting of water by electricity, and it was added in the intake manifold with a variable flow rate. The combustion and emissions characteristics were measured with a change in load at a constant speed. The In-cylinder Peak Pressure and Net Heat Release Rate improved with HHO gas addition. The ignition delay periods were longer, and combustion duration was reduced. Carbon Monoxide, Oxides of Nitrogen, and smoke opacity were reduced with the higher flow rate of HHO gas. However, Hydrocarbon and Carbon Dioxide emissions increased with the higher flow rate of HHO gas.KeywordsOxy-hydrogen gasCompression ignition engineCombustionEmissionsEarly direct injection
Article
Oxy-hydrogen gas (HHO) is a carbon-free fuel, which is produced by the water electrolysis process. It can be used as an alternative to hydrogen since the current global hydrogen production and storage may not meet the required demand for transportation applications. This research work investigates the engine behavior of a compression ignition (CI) engine operated in dual-fuel mode by inducting HHO as a primary fuel and injecting two different pilot fuels viz., diesel, and JME20 (a blend composed of 80% diesel with 20% Jatropha methyl ester) at optimized engine conditions. The results revealed that; heat release rate, brake thermal efficiency, exhaust gas temperature, and nitric oxide emission are found to be higher about 5.2%, 1.1%, 18.6%, and 19.6% respectively, while unburnt hydrocarbon, carbon monoxide, and smoke emissions are reduced by about 33.3%, 29.4%, and 18.7% respectively in Opt.JME20 + HHO operation compared to that of the baseline data at maximum load.
Full-text available
Article
Soybean oil based fatty acid methyl ester (FAME) is produced and blended with diesel fuel at 25% volumetric ratio. Besides, pure hydrogen (H 2) and compressed natural gas (CNG) mixture named HCNG fuel is used with 20 litres per minute (L/min) volumetric flow rates. The amount of liquid fuel injected into the cylinders is reduced by 30% via fuel pump plunger pin without structural changes on the diesel engine. Instead of the reduced liquid fuel, 20% hydrogen with 80% CNG gaseous fuel mixture (by volumes) are supplied by using mixing chamber before intake manifold of the test engine. Brake power, brake torque and brake specific fuel consumption and also thermal efficiencies are presented under performance outputs subsection. Results were compared and discussed. Additionally, exergy analysis of control volume has been performed. Using HCNG fuel enriched biodiesel effects on performance and energy efficiency are examined. Therefore comparison between diesel operation and alternative fuel usage is evaluated. Reference to this paper should be made as follows: Baltacıoğlu, M.K., Arat, H.T. and Kenanoğlu, R. (2017) 'Exergy and performance analysis of a CI engine fuelled with HCNG gaseous fuel enriched biodiesel', Int.
Full-text available
Article
In this study, an overview has been presented a classification of the vehicles using hydrogen with different ways. The using of hydrogen in vehicles has been categorized into two main categories as designs in which hydrogen is burned and energy is generated by conversion to electricity. The designs of internal combustion vehicles with using hydrogen via burning, the designs of the fuel cell vehicles that using hydrogen by converting into electricity and their hybrid versions have been introduced. In the automotive industry, the structure and future advantages of hydrogen fuel cell electric vehicles have been handled in a separate title. Onboard storage, safety, the capital cost and operating cost of the different design of vehicles have been analyzed rigorously.
Full-text available
Article
Main objective of this study is to compare performance and emission characteristics of a pilot injection diesel engine with the additions of alternative fuels like pure hydrogen, HHO and biodiesel. In order to achieve this goal, Helianthus annuus (sunflower) biodiesel was produced and blended with volumetric ratio of 10% with diesel fuel. Additionally, intake air was enriched with pure hydrogen or HHO via intake manifold without any structural changes except reduction of injected diesel fuel on the 3.6 L, four cylinders, four stroke diesel engines. Amount of Hydrogen fuel supplied to the engine was adjusted to constant 10 L/min during the experiments. The effects of pure hydrogen and HHO usage with the addition of biodiesel to the engine performance values (Brake Torque, Brake Power and Brake Specific Fuel Consumption) and exhaust emission values (NOx, CO2, CO) were investigated in between 1200 and 2600 rpm engine speeds. Engine performance values were increased with the enriching the intake air with HHO than pure hydrogen compared to the standard diesel fuel operating condition. On the other hand, in terms of exhaust gas emissions, pure hydrogen provided better results than HHO. In both cases, changes on the engine performance results were minimal however improvements on exhaust gas emissions were very promising.
Full-text available
Conference Paper
With increasing concern about energy shortage and environmental protection, research on reducing exhaust emissions, reducing fuel consumption, reducing engine noise and increasing specific outputs has become the major researching aspect in combustion and engine development. Alternative fuels such as CNG, HCNG, LPG, LNG, Bio-Diesel, Biogas, Hydrogen, Ethanol, Methanol, Di-Methyl Ether, Producer gas, P-series have been tried worldwide. Hydrogen as a future fuel for IC engines is also being considered. But several obstacles have to overcome before commercialization of Hydrogen as an IC engine fuel for automotive sector. Hydrogen and CNG blends (HCNG) may be considered as an automotive fuel without any major modification in the existing CNG engine and infrastructure. A strategy has been worked out for converting the developed CNG engine to run on HCNG. The testing is carried out for the neat CNG and 5% blends of Hydrogen by volume with CNG. It is observed in the experimental work that the HCNG engines are more superior to CNG carbureted engines from fuel economy, power output and emission compliance point of view. The power improvement of 11% and fuel consumption reduction of 8% is observed in HCNG engine than the CNG engine. The addition of hydrogen into natural gas increases the burning velocity of mixture, shortening the combustion duration, increasing the cylinder gas temperature, and this increases the effective thermal efficiency compared to that of natural gas engine under the same lean mixture condition. The HCNG engine increases the H/C ratio of the fuel, which drastically reduces the carbon based emissions such as CO, CO 2 and HC. To increase the flame speed of HCNG engines, the ignition timing needs to be retarded; this results in reduction of NOx emissions. It is important to note that 5% blends of hydrogen by volume with CNG the phenomenon of hydrogen embrittlement does not occur with respect to engine components, hence no major change is anticipated in fuel system and engine components. Moreover, it improves the engine efficiency, which lowers fuel consumption and hydrocarbon emissions. The research work is undertaken to demonstrate the viability of HCNG as an automotive fuel. This paper explains how CNG is the best route to ensure an early entry of hydrogen fuel into our energy infrastructure. This research work is carried out at Alternative fuel engine development lab, ARAI, Pune, India.
Article
Hydrogen and HHO enriched biodiesel fuels have not been investigated extensively for compression ignition engine. This study investigated the performance and emissions characteristics of a diesel engine fueled with hydrogen or HHO enriched Castor oil methyl ester (CME)-diesel blends. The production and blending of CME was carried out with a 20% volumetric ratio (CME20) using diesel fuel. In addition, the enrichment of intake air was carried out using pure HHO or hydrogen through the intake manifold with no structural changes – with the exception of the reduction of the amount of diesel fuel – for a naturally aspirated, four cylinder diesel engine with a volume of 3.6 L. Hydrogen amount was kept constant with a ratio of 10 L/min throughout the experiments. Engine performance parameters, including Brake Power, Brake Torque, Brake Specific Fuel Consumption and exhaust emissions – including NOx and CO, – were tested at engine speeds between 1200 and 2600 rpm. It is seen that HHO enriched CME has better results compared to pure hydrogen enrichment to CME. An average improvement of 4.3% with HHO enriched CME20 was found compared to diesel fuel results while pure hydrogen enriched CME20 fuel resulted with an average increase of 2.6%. Also, it was found that the addition of pure hydrogen to CME had a positive effect on exhaust gas emissions compared to that adding HHO. The effects of both enriched fuels on the engine performance were minimal compared to that of diesel fuel. However, the improvements on exhaust gas emissions were significant.
Conference Paper
Hydrogen enhanced combustion (HEC) is promoted as an end-user add-on that has the capability of reducing both engine tailpipe emissions and fuel consumption. An experimental investigation was carried out to measure the effects of HEC in typical engines through laboratory dynamometer testing. Three engines – (1) a carburetted petrol engine, (2) a fuel injected petrol engine and (3) a diesel engine – were tested to investigate the effects of adding hydrogen to the air intake of the engines and measure the effects on performance and emissions (HC, CO and CO2). The engines were tested at different engine speeds and loads to simulate a wide range of operating conditions. The hydrogen was produced from the electrolysis of a solution of distilled water and sodium hydroxide using two different electrolyser designs. The electrolyser constructions were suitable for automotive applications, that is, small in size and consuming current within the capability of a typical car alternator. Both the hydrogen and oxygen that were produced by electrolysis were added to the engine‘s intake during the tests. Results showed that the addition of HHO is most effective in stabilizing and enhancing the combustion of lean air-fuel mixtures inside the petrol injected engine, allowing for lower HC, CO and CO2 emissions. Thus hydrogen enhanced combustion could play a role in stabilizing lean burn petrol engines.
Chapter
: This chapter reviews the different types of gaseous fuel for vehicles, fuel production and distribution processes, engine/fuel systems and on-board storage options. this is followed by a discussion and comparison of life-cycle energy use and greenhouse gas (GHG) emissions. Finally, the advantages and limitations of each fuel are summarized along with a general discussion of future trends.