SINERGI Vol.
No.
October 2025: 625-632 http://publikasi.
id/index.
php/sinergi http://doi.
org/10.
22441/sinergi.
Experimental investigation of HHO blending in combustion engine performance Awaludin Martin.
Abda Hidayatullah.
Yogie Rinaldy Ginting.
Annisa Wulan Sari* Department of Mechanical Engineering.
University of Riau.
Indonesia Abstract The transition to renewable energy sources has become increasingly critical due to the adverse effects of greenhouse gas emissions.
One alternative to reducing fossil fuel dependence is hydrogen.
Hydrogen technology can be integrated into internal combustion engines without major design modifications.
This study investigates the effects of HHO gas blending on engine performance under varying brake load conditions.
The carburetor was modified to allow HHO gas from electrolysis to enter the combustion chamber.
The results indicate that HHO blending led to a 4.
9% increase in brake power, a 66% improvement in thermal efficiency, and a 3% reduction in brake-specific energy consumption (BSEC).
Additionally, among different potassium hydroxide (KOH) concentrations, the 30% wt solution exhibited the lowest power consumption for electrolysis.
This is an open-access article under the CC BY-SA license.
INTRODUCTION
The greenhouse gases has contributed to rising global temperatures .
, 2, .
In response, various nations have committed to limiting temperature increases to below 1.
5AC and achieving net-zero emissions by 2050, as outlined in the COP26 Reducing fossil fuel usage is imperative to achieving these targets, and hydrogen is a promising alternative due to its high energy density and clean combustion properties .
, 5, .
In order to achieve these targets, fossil energy reduction must be implemented globally by all stakeholders.
An alternative renewable energy in reducing the use of fossil fuels is hydrogen .
Hydrogen as a fuel produces heat and water as emissions.
The heating value of hydrogen gas is about 142.
18 MJ/Kg (HHV) and 120 MJ/Kg (LHV) at 25oC .
The value of hydrogen is much higher than other fuels.
Table 1 provides the significant differences characteristics between hydrogen and other fuels, highlighting the advantages of hydrogen gas.
Keywords:
Electrolysis.
Hydrogen.
Internal Combustion.
Performance.
Article History:
Received: September 24, 2024 Revised: January 23, 2025 Accepted: February 17, 2025 Published: September 2, 2025 Corresponding Author:
Annisa Wulan Sari Mechanical Engineering Department.
Universitas Riau.
Indonesia Email:
annisasw@lecturer.
Table 1.
Comparison of Hydrogen.
Gasoline, and Diesel Properties .
Properties Auto-ignition temperature (K) Laminar lame AFR .
g/k.
Lower Heating value .
J/k.
Gasoline Diesel
0,3-0,4
0,3-0,4
Hydrogen can be produced through several methods, including hydrocarbon reforming .
rey hydroge.
, carbon capture-enhanced reforming .
lue hydroge.
, biomass processing, and electrolysis powered by renewable energy .
reen hydroge.
Electrochemical water electrolysis is a environmentally friendly hydrogen gas.
This process involves applying direct current (DC) electricity to break the bond energy of water molecules, separating them into hydrogen and oxygen elements with a purity of up to 99.
99% .
Martin et al.
Experimental investigation of HHO blending in combustion engine A SINERGI Vol.
No.
October 2025: 625-632 The chemical reactions involved in the electrolysis process are as follows .
Reaction = 2H2O.
Ie 2H2 .
O2.
Anode Katode = 2H2O.
Ie O2.
H .
4e = 4H .
4e Ie 2H2.
Under standard conditions, the enthalpy .
H) of water is 285.
85 kJ/mol, as calculated using the following equation:
2H2O.
Ie 2H2 .
O2.
iH = 285,85 kJ/mol .
iH is the sum of:
= iG TiS Where iG = 237,13 kJ/mol .
TiS = 48,72 kJ/mol .
Gibs free energy .
G) in electrolysis is the minimum energy required for the electrolysis The minimum voltage (Ere.
can be calculated through the following equation:
ERev = iG = 1,23 V yc.
At the same time, energy input during the electrolysis process influences temperature (T) and entropy .
S).
Consequently, the minimum voltage (VTN) required for the electrolysis process under standard conditions is determined by the following equation:
VTN = iH = 1,48 V yc .
F is Faraday's constant (F=96485 C/mo.
, and z is the number of electrons .
for hydrogen and 4 for In practice, the voltage required for electrolysis exceeds the theoretical minimum because of overpotential caused by resistive losses, reaction kinetics, gas pressure, electrode conductivity, electrolyte conductivity, distance between electrodes, and gas bubbles on the electrode surface .
The theoretical volume of hydrogen production is determined using the following equation .
ycOyco .
yc ycOya2ycnyccyceycayco = .
ya Where ycOya ycnyccyceycayco is the theoretical volume of hydrogen, i is the current strength (A), t is the time .
, and F is Faraday's constant .
485 C/mo.
Vm is the molar volume.
An internal combustion engine can blend modifications to its design.
Blending hydrogen gas with fossil fuels improves combustion efficiency by reducing energy losses .
It also enhances flame ignition properties and improves the combustion characteristics of hydrocarbon fuels .
Hydrogen plays a key role in reducing exhaust emissions from the transportation sector.
The global vehicle count is projected to reach 1.
billion by 2035, continuing to consume fossil fuels and emit pollutants that contribute to greenhouse gas emissions .
Therefore, hydrogen offers a practical approach to accelerating the energy transition while maintaining economic activity .
Gad et al.
utilized electrolyzed gas at 5 LPM, mixed with gasoline engine combustion at 3000 rpm.
This study showed an increase in volumetric efficiency, thermal efficiency, and airfuel ratio by 7.
5%, 8%, and 11%, respectively, reduced SFC by 9%, and reduced CO.
HC.
NOx, and CO2 production by 18%, 9%, 15%, and 11%.
Purayil et al.
tested a singleslider spark ignition engine with variations of 5 mg to 6 mg of gasoline and variations of hydrogen between 2, 5, 8, 11, and 14 LPM.
This study showed that hydrogen gas at a flow rate of up to 11 LPM significantly reduces brake-specific energy consumption (BSEC) by 92.
27% and increases BTE by 25%.
Hassan et al.
used a spark ignition engine with a capacity of 183 cc to mix hydrogen gas at 1500 rpm engine speed.
The results showed an increase in engine efficiency by up to 24%, reduced BSEC by up to 32.
1%, reduced CO production by up to 91.
7%, and reduced HC by up to 34.
Adaileh and al Qdah .
investigated the effects of using 3 LPM HydrogenHydrogen oxygen (HHO) gas.
The results showed an increase in adequate shaft power from 1198.
watts to 1413 watts.
Specific Fuel Consumption (SFC) decreased from 968 g/kW to 792 g/kW, and BTE improved from 16.
93% to 23.
Furthermore.
The HC emissions decreased from 240 ppm to 215 ppm.
Assad and Penazkov .
showed that the concentration of hydrogen in mixing fuel and air could reach 20% of the total air entering the This study also showed that using up to 20% of hydrogen increased the pressure in the combustion chamber by 19% to reach 5.
8 Mpa, and the temperature in the combustion chamber increased by 140 K.
Based on the literature.
HHO gas has proven to be a promising fuel for internal combustion engines.
Previous studies have focused on understanding the effects of blending HHO in combustion engines, examining various parameters such as HHO flow rates, engine speed, and cylinder capacity .
, 20, 21, .
However, further analysis is still needed to evaluate the impact of HHO addition on engine performance under varying load conditions.
Martin et al.
Experimental investigation of HHO blending in combustion engine A p-ISSN: 1410-2331 e-ISSN: 2460-1217 This study aims to investigate the effects of HHO blending on engine performance under varying brake loads, focusing on parameters such as brake power (BP), brake-specific energy consumption (BSEC), and brake thermal efficiency (BTE).
METHOD
Hydrogen Electrolyzer Setup The electrolyzer design in this study, which was developed and finalized prior to the commencement of the experiments, is detailed in Table 2, highlighting the pre-determined arrangement of components such as the electrodes, neutral plates, and electrolyte flow system to ensure compatibility with the research objectives and operational conditions.
The illustration of the electrolyzer are provided in Figure 1.
The stack consists of 2 cells, each containing one anode plate .
and one cathode plate .
, one neutral plate .
ot electrifie.
between the anode and cathode with a distance of 3 mm from each plate.
Each plate is made of stainless steel 316 due to its high corrosion resistance and durability in alkaline solutions, while the neutral plate serves to minimize electrical interference between the anode and cathode.
The power source was a 12V 60Ah A 12V 60Ah battery supplied power, with current variations of 30A, 40A, and 50A applied for each KOH concentration .
% wt, 25% wt, and 30% w.
The gas production rate and power consumption were measured using a flow meter and a wattmeter.
Based on these evaluations, the electrolysis tests revealed that the average gas production rates at current strengths of 30A, 40A, and 50A were 0.
25 L/min, 0.
3 L/min, and 0.
L/min, respectively.
Therefore, the electric power consumption for all currents at each molarity variation was recorded using a wattmeter.
Table 2.
Specification of Electrolyzer Parameters Type of Electrolyzer Type of Electrode Dimension of Elektroda Number of cells Number of stacks Number of neutral plates Capacity of electrolyzer Description Wett Cell Stainless Steel 316 1 mm X .
X .
cm 1 Liter .
Figure 1.
Electrolyzer Circuit: Anode.
Cathode, and Neutral Plate .
Electrolyzer Parts .
Experimental Procedure The experiments were conducted in the Energy Conversion Laboratory at the University of Riau.
Figure 2 illustrates the schematic of the experimental setup used in this study.
The flow rate of the gas was measured using a flow meter.
The gas was then transported through a pipe, blended with air, and directed into the intake manifold via the carburetor.
The engine used in this experiment was a three-cylinder, four-stroke gasoline engine, as detailed in Table 3.
The fuel used was gasoline with an octane rating of 90, commonly known as Pertalite.
The experiment began when the engine speed reached 2200 rpm, at which point the generated HHO gas was directed into the carburetor through a pipeline.
A flashback arrestor was installed for safety.
Brake loading was varied 25 kg/cmA, 0.
5 kg/cmA, and 0.
75 kg/cmA.
The engine speed and fuel consumption time were recorded using a tachometer and a stopwatch while consuming 5 ml of fuel.
The first experiment began with gas generated from a 30A current at 20%wt KOH, which produced 0.
25 LPM HHO gas, and the brake load was set at 0.
25 kg/cm2.
Since the engine was operated under variations in the brake loading and KOH molarity, the effects of gas addition on engine performance were analyzed using the following parameters Table 3.
Specification of Gasoline Engine Parameters Type of machine Number of cylinders Capacity of the cylinder Ratio compression Bore x stroke Maximum Power Maximum Torque Description 3-cylinder, four-stroke 993 cc 76 mm x 73 mm 59 kW/ 5600 RPM 5 Nm/3200 Martin et al.
Experimental investigation of HHO blending in combustion engine A SINERGI Vol.
No.
October 2025: 625-632 Figure 2.
Schematic Experimental Setup The effects of HHO blending were analyzed by evaluating BP.
BSEC, and BTE, calculated using the following equations:
yaAycE = BSEC = yaAycNya = (Ayci .
yayaycOyci Aya2 .
ya2 ) (J/.
ycAyce x 100 (%) ycAyce (Ayci .
yayaycOyci Ayci .
yayaycO ya2 ) RESULTS AND DISCUSSION This experiment consists of two stages.
the first stage, the electrolyzer generates HHO gas by varying the current and molarity of potassium hydroxide (KOH).
During this stage, the average HHO production and electricity consumption were measured by a flowmeter and a wattmeter.
In the second stage, the HHO gas and air mix in the combustion engine.
The HHO flow rate used was the average data obtained from the first stage.
Then, the engine performance was analyzed by comparing the performance before and after blending HHO gas.
Energy Consumption for HHO According to Ohm's law, a higher potential difference .
results in a greater flow of current, facilitating the conduction of free ions.
However, resistance within the systemAisuch as that in the electrodes, electrolytes, and reaction containerAicauses a decrease in the input electric current after passing through the electrolysis The voltage and current flowing through the system directly impact power consumption.
Therefore, if power consumption is not proportional to hydrogen production, the process will not be economically efficient .
Variations in current strength of 30A, 40A, and 50A were tested for each molarity of KOH .
%wt, 25%wt, and 30%w.
Based on electrolysis tests in each variation in KOH molarity, the average gas production rate at current strengths of 30A, 40A, and 50A was 0.
LPM, 0.
3 LPM, and 0.
4 LPM, respectively.
The test also showed that to achieve these gas flow rates, the electric power consumption decreased by 30%wt KOH electrolyte compared to 25%wt and 20%wt KOH.
Figure 3 indicates that the electrical power consumption decreases as the molarity of KOH The phenomenon is explained by the catalytic properties of KOH, which accelerate reaction kinetics and reduce water resistance.
Lower resistance allows more ions per unit of time to separate H2O into its elements .
At a KOH concentration of up to 30%wt, the specific electrolyte conductivity is significantly higher compared to lower concentrations.
Higher conductivity reduces the voltage required for the electrolysis process.
As a result, power electrolyzer's efficiency in producing the same amount of gas .
Martin et al.
Experimental investigation of HHO blending in combustion engine A 3,73 3,82 3,87 3,91 2,52 2,58 2,61 2,63 0,25 1,28 1,31 1,31 1,32 Brake Power .
W) Energy Consumption (W) p-ISSN: 1410-2331 e-ISSN: 2460-1217 Flow Rate Gas HHO (L/Mi.
20wt% 25wt% 30%wt Figure 3.
Energy Consumption vs Flowrate Gas
HHO
The Effects of HHO Gas on the Internal Combustion Engine As brake loading increases, the engine generates higher torque to maintain stable The demand for higher torque leads to increased fuel consumption, which subsequently raises brake power output.
The trend observed in Figure 4 illustrates the relationship between brake power and brake loading.
At lower brake loading levels, the increase in brake power is relatively modest due to the lower torque demand.
However, at higher loading levels, the increase becomes more significant.
Figure 4 shows the addition of varying HHO flow rate, blended in the combustion chamber, under different brake loading conditions.
The addition of HHO enhances the brake power output at the same brake loading levels.
The improvement occurs because the HHO gas acts as an auxiliary fuel, improving the engine performance by enhancing the flame speed and helping the fuel burn more completely.
This leads to a more efficient energy conversion, which directly contributes to the observed increase in brake power.
In this experiment, the most significant increase in brake power, up to 4.
9%, occurs when the brake load is 0.
75 kg/cm2, increasing from 3.
kW to 3.
91 kW with the addition of 0.
4 LPM HHO.
Nabil et al.
, also observed an increase in brake power using HHO flow rates of 0.
47 LPM to 51 LPM.
Their results showed a brake power increase of up to 17.
9% in a 150 CC engine and 4% in a 1300 CC engine.
The difference in brake power gain was influenced by variations in engine capacity and rotation speed, which determine the amount of HHO burned during each combustion cycle.
An increase in brake power indicates improved engine performance.
0,25
0,75
Brake Loading .
g/cm.
0 L/m 0,25 L/m 0,3 L/min 0,4 L/m Figure 4.
Brake Loading vs Brake Power Brake-specific energy consumption (BSEC) was analyzed by observing the fuel consumption required to generate brake power.
Higher brake loading results in reduced fuel consumption because the engine speed decreases, which in turn reduces the amount of fuel injected into the combustion chamber.
A decrease in fuel consumption to generate a brake power at the same brake loading indicates improved efficiency.
Figure 5 shows the effect of all variations of HHO blending under varying brake loading conditions on the BSEC.
The experiment shows that HHO blending reduces fuel consumption under all brake load conditions, with the most significant reduction observed in BSEC, up to 3%, occurring at a brake load of 0.
25 kg/cm2 with an HHO flow rate of 0.
4 LPM.
the decrease is from 75 MJ/kWh to 5.
57 kWh.
A similar trend in BSEC reduction was also reported by Purayil et al.
, who used hydrogen flow rate variations of 2, 5, 8, 11, and 14 LPM.
The most significant BSEC reduction was obtained 5 Mj/kWh to 3.
7 MJ/kWh, representing a 92% decrease at a hydrogen flow rate of 11 LPM.
The same result was also obtained by Gad et al.
This study used 0.
5 LPM HHO, with A decrease in specific fuel consumption (SFC) by up to 9%.
The reduction in BSEC observed in the experiment can be attributed to the unique combustion characteristics of HHO gas.
Its high diffusivity enables homogeneous mixing with air in the combustion chamber .
, while its high flammability and heating value accelerate the combustion process, enhancing energy release .
Additionally, its high burning speed shortens the combustion duration, optimizing the conversion of thermal energy into mechanical These properties collectively improve the combustion efficiency of the air-fuel mixture, as evidenced by the reduction in fuel consumption observed in this study .
Martin et al.
Experimental investigation of HHO blending in combustion engine A 0,25 0,75 Brake Loading .
g/cm.
0 L/m 0,25 L/m 0,3 L/m 0,4 L/m Figure 5.
Brake Loading vs BSEC Thermal efficiency was also evaluated in this study, with the results presented in Figure 6.
The findings indicate that thermal efficiency improves with increasing brake loading.
As brake load increases, the engine operates closer to its optimal efficiency range, where a larger proportion of combustion energy is converted into useful This reduces the relative impact of frictional and thermal losses on total energy output.
The results also show that thermal efficiency increases with higher HHO gas flow This improvement can be attributed to the combustion characteristics of HHO gas.
The hydrogen content in HHO has a high burning speed, enabling faster and more complete combustion of the primary fuel.
Additionally, the homogeneous mixing of HHO with air ensures an optimal air-fuel mixture, minimizing unburned hydrocarbons and reducing energy losses.
Consequently, the conversion of chemical energy into mechanical work is enhanced, leading to increased thermal efficiency.
The experiment demonstrates the potential of HHO gas to improve thermal efficiency without requiring significant modifications to engine design under varying brake load conditions.
provides a more straightforward approach to emission reduction compared to other green energy solutions, such as electric vehicles.
The use of hydrogen presents a practical pathway for accelerating the energy transition while maintaining economic activity.
Therefore, it offers an immediate solution to reducing fuel consumption and lowering emissions at an early The highest improvement in thermal efficiency, up to 1,66%, was achieved at an HHO flow rate of 0.
4 LPM and a brake load of 0.
kg/cm2.
The result showed that efficiency increased from 63.
37% to 65%.
63,37
64,41
64,84
65,03
41,77
42,71
42,84
42,91
20,79
21,23
21,38
21,31
Thermal Efficiency (%) 5,75 5,59 5,59 5,57 8,66 8,49 8,48 8,45 17,25 16,97 16,96 16,89 BSEC (MJ/kW.
SINERGI Vol.
No.
October 2025: 625-632
0,25
0,75
Brake Loading .
g/cm.
0 L/m 0,25 L/m 0,3 L/m 0,4 L/m Figure 6.
Brake Loading vs Thermal Efficiency Although the improvements observed in this study are less significant than those reported by Gad et al.
n 8% increase in thermal efficiency with 0.
5 LPM HHO in a single-cylinder engin.
and Adaileh & Al Qdah .
n increase in BTE from 16.
93% to 23.
48% with 3 LPM HHO in a four-cylinder engin.
They provide valuable insights into the effects of HHO blending in multicylinder engines using a relatively lower HHO flow This relatively modest improvement suggests that the effectiveness of HHO is influenced not only by its flow rate but also by engine configuration and combustion characteristics.
The data in Table 4 shows that the improvement of engine performance does not necessarily scale linearly with HHO flow rate.
For example, while Hassan et al.
achieved a 24% increase in efficiency with only 0.
2 LPM
HHO in a single-cylinder engine.
The present study of 0.
4 LPM HHO in a three-cylinder engine resulted in only a 1.
6% increase.
One possible reason for the smaller improvement observed in this study is the use of a multi-cylinder engine, which distributes the HHO mixture differently compared to the single-cylinder setups used in previous research.
Table 4.
Comparison between the Present Study and Some of the Previous Studies Author Flowrate HHO (LPM) Cylinder Thermal Efficiency .
Increase 8% .
Present Increase Increase Increase Increase SFC/ BSEC Decrease Decrease Decrease Decrease Decrease Martin et al.
Experimental investigation of HHO blending in combustion engine A p-ISSN: 1410-2331 e-ISSN: 2460-1217 Additionally, the lower HHO flow rate .
4 LPM)
may have contributed to the more moderate enhancement in engine performance.
Despite the modest improvements, this study demonstrates that even at lower HHO flow rates, positive effects on engine performance can still be achieved.
This is particularly significant for practical applications, where using less HHO offers a more sustainable and cost-effective approach to improving fuel efficiency and reducing CONCLUSION This experiment demonstrates that HHO blending enhances brake power, improves thermal efficiency, and reduces fossil fuel consumption under controlled load conditions.
The findings highlight its potential as a practical and viable solution for reducing fossil fuel consumption in daily applications.
The key results obtained are as follows:
Effect of KOH Molarity on Electrical Power Consumption The results show a decreasing trend in electrical power consumption as KOH molarity The lowest power consumption across all variations of current strength and KOH molarity was observed at a KOH concentration of 30% wt.
Effect of HHO Blending on Engine Performance HHO blending in the combustion chamber led to improved engine performance.
The optimal performance was achieved at an HHO flow rate of 4 L/min, resulting in a 4.
9% increase in brake power, a 1.
6% improvement in thermal efficiency, and a 3% reduction in brake-specific energy ACKNOWLEDGMENT The authors gratefully acknowledge the generous financial support given by the DIPA LPPM through the RIPEKDOM Scheme - in accordance with the Fiscal Year 2024 Research Contract University of Riau of Contract Number:
942/UN19.
3/AL.
04/2024.
REFERENCE