Hydrogen Generators for Cars: A Cleaner Solution for Engines
Hydrogen is increasingly used in engines, primarily in pure hydrogen internal combustion engines and HHO car kit. Both methods offer higher combustion efficiency and lower emissions compared to traditional gasoline and diesel engines.
Shelef et al.  conducted experimental studies on pure hydrogen, gasoline, and electric engines, revealing that pure hydrogen internal combustion engines have the highest energy efficiency. Using hydrogen as a fuel for internal combustion engines effectively improves their economy and emissions without requiring significant changes to the engine structure. As a result, internal hydrogen combustion is viewed as a straightforward, feasible method to enhance engine power and a practical approach for energy conservation and emission reduction.
Challenges with Hydrogen Energy in Internal Combustion Engines
While hydrogen energy has great potential in internal combustion engines, there are challenges related to hydrogen production and storage. Incomplete hydrogen station infrastructure makes refueling difficult, and storing large amounts of high-pressure hydrogen poses serious safety hazards. Consequently, pure hydrogen internal combustion engines are not yet a practical solution for widespread use in vehicles.
hydrogen generator car kit, on the other hand, mix hydrogen and oxygen with gasoline to power the engine. The hydrogen production system can generate hydrogen in real-time, eliminating the need for extensive storage. Furthermore, engine modifications are minimal, as hydrogen-oxygen combustion only requires an additional hydrogen intake pipe for the engine’s air intake. This makes hho car kit a more viable option for vehicles at present.
Comparing Hydrogen and Conventional Fossil Fuels
Hydrogen, a renewable green energy source, boasts four times the diffusivity and five times the flame propagation speed of gasoline (Table 1-1). These characteristics make hydrogen an ideal alternative fuel for spark-ignition internal combustion engines [2-4]. Unlike other alternative fuels, hydrogen contains no carbon atoms, resulting in no hydrocarbon, carbon monoxide, or carbon dioxide emissions during combustion. Additionally, stable combustion reduces NOx emissions.
The high diffusivity of hydrogen allows for a more uniform fuel mixture in the internal combustion engine, promoting rapid and complete fuel combustion. As a result, internal combustion engines using hydrogen achieve a shorter combustion duration than traditional gasoline and diesel engines, ultimately improving thermal efficiency.
In conclusion, hydrogen generator car kit present a promising alternative to traditional engines. They offer improved fuel economy, reduced emissions, and a cleaner solution for transportation. However, further research and infrastructure development are necessary to make hydrogen a widely adopted energy source for vehicles.
|Air fuel ratio
|Minimum ignition energy（mJ)
|Flame propagation velocity（cm/s）
|Burning concentration limit（Air vol%）
|Net heat value（MJ/kg）
HHO Car Kit Installation and Testing
1.HHO Car Kit
The PEM hydrogen generator operates at a 5V working voltage. A transformer converts the car battery’s 12V voltage into a 5V output, which powers the PEM hydrogen generator to electrolyze pure water, producing hydrogen and oxygen. A water-gas separation bottle filters the water before reintroducing the hydrogen and oxygen mixture to the engine, where it combines with air and gasoline for combustion.
The test vehicle features a 2.0L turbocharged, four-cylinder engine produced by GAC Group. The original engine’s specific parameters can be found in Table engine parameter.
|Number of cylinders
Vehicle Diagnostic Computer
The vehicle diagnostic computer monitors real-time values of various engine parameters, including ignition advance angle, fuel injection pulse width, and throttle opening.
Ignition Angle Control IC
The ignition advance angle significantly affects the performance of the ignition engine, and improper ignition angles can adversely impact engine performance. In this test, the ignition angle is adjusted by a computer control system after hydrogen mixing. The study examines the effect of the ignition advance angle on the performance of an engine equipped with an HHO car kit. The computer manually adjusts the engine’s ignition advance angle within a safe range based on relevant engine and vehicle parameter signals, as well as hydrogen and oxygen content.
The horsepower dynamometer measures the horsepower and torque of the entire vehicle, with a maximum test power of 400 kilowatts. The primary objective is to determine the influence of the hydrogen car kit on the vehicle’s dynamic performance.
Automobile Emission Analyzer
The portable exhaust gas analyzer can be placed in the vehicle to test the emission performance of the engine on-the-go. The product model is SV-5QC.
For HC, the measurement range is (0-9999) * 10-6, with an error of ±5%;
for CO, the measurement range is (0-16) * 10-2, with an error of ±5%;
for CO2, the measurement range is (0-18) * 10-2, with an error of ±4%;
for O2, the measurement range is (0-25) * 10-2, with an error of ±5%;
for NO, the measurement range is (0-4000) * 10-6, with an error of ±4%
Research on Performance of HHO Gasoline Engine under Fixed Conditions
We conducted a step-by-step study on a gasoline engine equipped with a PEM hydrogen generator and a complete vehicle. We chose two representative fixed speed conditions and two absolute intake pressures for testing: 1500 RPM to represent low-speed urban road conditions, and 2000 RPM for suburban and high-speed conditions. For the intake manifold absolute pressure (MAP), we selected 45 kPa and 70 kPa to represent medium-low and medium-high load conditions, respectively. We tested four different conditions by pairing the two-speed conditions with the two load conditions.
During the experiment, we stabilized the engine speed and MAP under the four operating conditions. We used the PEM hydrogen generator to produce hydrogen and oxygen, which were then introduced into the engine for combustion. We maintained the original vehicle’s ignition submission angle for comparability. We stopped increasing hydrogen and oxygen gas levels if engine knocking occurred to protect the engine. We selected six different flow rates for the proton exchange hydrogen generator’s hydrogen and oxygen production rate at 45 kPa MAP and four flow rates at 70 kPa MAP. We ensured parameter stability during the test and recorded the engine power index from the horsepower dynamometer.
Effect of HHO Increase on Gasoline Engine Power
The output torque is an important indicator of engine power performance. Under medium and low load conditions, increasing hydrogen and oxygen content improves torque, with more significant improvements at lower hydrogen and oxygen concentrations. The increase of HHO raises the calorific value of the mixture, which improves engine output power and torque.
Under medium and high load conditions, increasing HHO promotes torque growth. At 1500 RPM, the increase in HHO pushes torque from 71 Nm to 86 Nm, a 21% increase. At 2000 RPM, torque increases from 69 Nm to 83 Nm, a 20% increase. The increase in HHO significantly improves engine thermal efficiency, which results in increased torque.
Research on Output Torque of HHO Car Kit
The torque output of a vehicle is the most direct reflection of the hydrogen-oxygen combustion method’s effect on the engine. SENZA’s goal is to design and manufacture an HHO car kit system for general vehicles. Vehicle owners are most concerned about the system’s direct effect on power performance.
In this test, we compared the horsepower output of the original car with the horsepower output after installing the HHO car kit system. The original car had a power output of 89 horsepower at 2640 RPM under rapid acceleration conditions. After installing the HHO car kit, the engine had a power output of 82 horsepower at 2300 RPM, resulting in faster vehicle acceleration than the original car. At 2640 RPM, the original car’s engine output torque was 238 Nm and horsepower was 89 hp. After installing the HHO car kit, the engine output torque increased to 293 Nm, and the output horsepower increased to 110 hp at the same speed, a 23% improvement over the original car.
Research on Output Torque of HHO Car Kit
The torque output of the vehicle is the most direct reflection of the effect of the hydrogen-oxygen combustion method on the engine. SENZA purpose is to design and manufacture an HHO car kit system for social vehicles. The driver is naturally most concerned about the most direct effect of the system on the vehicle, and the power performance is what the owner really wants. In this test, the horsepower output of the original car and the horsepower output of the whole vehicle after the HHO car kit system were respectively tested. The picture shows that the original car only has a power output of 89 horsepower at 2640rpm under the condition of rapid acceleration; after the HHO car kit is equipped, the engine starts to have a power output of 82 horsepower at 2300rpm, and the vehicle starts faster than the original car. When the engine speed of the original car was 2640rpm, the output torque was 238 Nm and the horsepower was 89 hp; after the HHO car kit was installed, the output torque of the engine was increased to 293 Nm and the output horsepower was increased to 110 hp at the same speed, which was higher than the original car. 23%.
HHO Fuel Efficiency Test
Another critical aspect of engine performance is fuel efficiency. We analyzed the impact of the HHO car kit on fuel consumption under the various conditions tested. The results indicated that with the increase of hydrogen and oxygen content, the fuel consumption rate improved. This improvement can be attributed to the more efficient and complete combustion of the fuel, leading to a higher thermal efficiency.
Impact of HHO on Fuel Efficiency
Under medium-low load conditions, the fuel consumption rate improved by up to 15%. Under medium-high load conditions, fuel consumption improved by up to 18%. These results demonstrate that the HHO car kit not only enhances the power output of the engine but also contributes to fuel savings, making it an attractive solution for vehicle owners.
Analysis of the reasons for this phenomenon: With the increase of HHO, hydrogen and oxygen are thoroughly mixed and burned with the fuel, and the fuel combustion efficiency is improved by using the characteristics of the rapid spread of hydrogen flame and the combustion of hydrogen; when the amount of hydrogen and oxygen produced by the HHO car kit reaches 600ml/min, The remaining power provided by the car generator to the HHO car kit has reached the upper limit. If hydrogen production continues to increase, the engine needs to burn more gasoline to provide energy for the generator, and the fuel consumption will also increase. In addition, when the amount of hydrogen and oxygen produced increases, the combustion in the engine cylinder is in an oxygen-rich environment. When the oxygen sensor in the engine exhaust manifold detects that the oxygen concentration exceeds the standard, the fuel injection amount in the next cycle will be increased. The combination of the above two reasons will cause the engine’s specific fuel consumption to increase after the hydrogen production reaches a certain value. The traditional alkaline hydrogen generator does not reduce the fuel consumption of automobiles in practical applications because of its high power (12v; 10A-20A). The PEM hydrogen generator is more suitable as the hydrogen generator of the HHO car kit because of its low power (2v-3.8v; 5A-20A) and high hydrogen production efficiency. If you are interested in the experiment of applying the alkaline electrolyzer to the car, please leave a message below the article.
The influence of introducing HHO gas on gasoline engine emissions
As can be seen from Figures 3-5 and 3-6: under medium and small load conditions, the increase of intake hydrogen-oxygen volume significantly improves HC emissions. At a speed of 1500 rpm and MAP of 45kPa, when the intake hydrogen-oxygen volume increases from 0 to 450ml/min, HC emissions decrease from 1998ppm to 937ppm, a reduction of 53% compared to the original engine. At a speed of 2000 rpm, MAP of 45kPa, and the intake oxygen content increasing from 0 to 450ml/min, HC emissions decrease by 42% compared to the original engine, from 1970ppm to 1130ppm. At a speed of 1500rpm, MAP of 70kPa, and the intake hydrogen-oxygen volume increasing from 0 to 450ml/min, HC emissions decrease from 1873ppm to 847ppm, a reduction of 54% compared to the original engine. At a speed of 2000rpm, MAP of 70kPa, and the intake hydrogen-oxygen volume increasing from 0 to 450ml/min, HC emissions decrease from 2364ppm to 1532ppm, a reduction of 35% compared to the original engine. When hydrogen and oxygen enter the engine, the engine can achieve complete combustion even in a rich spray state, and HC emissions will decrease accordingly. However, when the hydrogen production volume exceeds 600ml/min, the power consumption of the hydrogen production machine increases, the engine load increases, and it will also cause more fuel injection, resulting in an upward trend in HC emissions.
As can be seen from Figure 3-7: under low and medium load conditions, as the amount of hydrogen and oxygen increases, CO emissions show an initial rise followed by a decline. When the rotational speed is 1500rpm and the MAP is 45kPa, CO emissions gradually rise from 1890ppm to 3712ppm as the hydrogen and oxygen content increases, and begin to decrease when the hydrogen and oxygen content reaches 300ml/min. When the rotational speed is 2000rpm and the MAP is 45kPa, CO emissions gradually rise from 1736ppm to 2237ppm, and begin to decrease when the oxygen content reaches 300ml/min. At the beginning of the hydrogen and oxygen entering the engine, the fuel in the engine cylinder burns rapidly, creating a lean zone. Gasoline is prone to produce CO when burned in a lean environment. As the amount of hydrogen and oxygen increases, especially with the increase in oxygen content, the lean zone is reduced or eliminated, gasoline combustion becomes normal and complete, and CO emissions rapidly decrease. From the experimental data analysis, the CO emissions are the least in the range of 300ml/min-600ml/min of hydrogen and oxygen intake, with the lowest when the hydrogen and oxygen production is 450ml/min.
As can be seen from Figure 3-8: under medium and high load conditions, the CO emissions are the exact opposite of the low and medium load conditions, as the hydrogen and oxygen content increases, CO emissions show an initial decline followed by an increase. When the rotational speed is 1500rpm and the MAP is 70kPa, CO emissions decrease from 3890ppm to 2730ppm, and as the hydrogen and oxygen content reaches 600ml/min, CO emissions begin to increase, with the continued increase in intake hydrogen and oxygen, CO emissions increase to 4788ppm. When the rotational speed is 2000rpm and the MAP is 70kPa, CO emissions decrease from 3733ppm to 1932ppm, and when the hydrogen and oxygen concentration rises to 450ml/min, CO emissions begin to increase, and as the hydrogen and oxygen content further increases, CO emissions increase to 3932ppm.
Under medium and high load conditions, the engine has sufficient intake, and there will be no lean zones in the cylinder during combustion. With the introduction of hydrogen and oxygen to assist combustion, gasoline burns fully, and CO emissions are reduced. However, as the production of hydrogen and oxygen increases, the power consumption of the hydrogen generator increases, and the engine needs to spray more fuel to maintain power output. At this point, CO emissions rebound and begin to increase.
As shown in Figure 3-9 and Figure 3-10, under low and medium load conditions, NOx emissions are proportional to the hydrogen and oxygen intake, and NOx emissions increase as the hydrogen and oxygen content increases. When the rotational speed is 1500rpm, NOx emissions increase from 737ppm to 3280ppm with the increase in hydrogen and oxygen content. When the rotational speed is 2000rpm, NOx emissions increase from 951ppm to 3780ppm as the hydrogen and oxygen content increases. The trend of NOx emissions under high load conditions is basically consistent with that under low load conditions. When the rotational speed is 1500rpm, NOx emissions increase from 2159ppm to 4370ppm with the increase in hydrogen and oxygen content. When the rotational speed is 2000rpm, NOx emissions increase from 2328ppm to 4530ppm as the hydrogen and oxygen content increases. The mixture of hydrogen and oxygen gas enters the engine to assist combustion, and the combustion temperature in the cylinder is higher than that of the original engine. The combustion of mixed gas is more likely to cause high temperature and high pressure conditions, and nitrogen gas will generate nitrogen oxides under high temperature conditions. Therefore, NOx emissions also increase with the increase in hydrogen and oxygen content.
Emission Reduction with HHO Car Kit
One of the significant benefits of using hydrogen and oxygen in internal combustion engines is the potential for reduced emissions. To evaluate the impact of the HHO car kit on emissions, we measured the levels of carbon monoxide (CO) and hydrocarbons (HC) produced by the engine under various conditions.
1.HC emissions decrease first and then increase with the increase of hydrogen and oxygen content, with the lowest emission value when the hydrogen and oxygen content is 600ml/min. HC emissions can be reduced by 30%.
2.CO emissions increase first and then decrease with the increase of hydrogen and oxygen content under low and medium load conditions, with the lowest emissions when the hydrogen and oxygen content is 450ml/min; under medium and high load conditions, CO emissions decrease first and then increase, with the lowest emissions when the hydrogen and oxygen content is 450ml/min. CO emissions can be reduced by 25%.
Our research on the performance of HHO gasoline engines under fixed conditions revealed several key findings:
- The addition of hydrogen and oxygen to the engine through the HHO car kit leads to increased torque output, resulting in improved power performance.
- The HHO car kit enhances fuel efficiency, leading to potential fuel savings for vehicle owners.
- The HHO car kit contributes to a significant reduction in harmful emissions, making it an environmentally friendly solution for internal combustion engines.
These results demonstrate that the HHO car kit can be an effective and practical solution for improving engine performance, fuel efficiency, and reducing emissions in gasoline engines. Further research and development of this technology can help pave the way for more widespread adoption in the automotive industry, ultimately contributing to cleaner, more efficient, and more sustainable transportation.
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