Introduction & Summary
Partial hydrogen injection (PHI) is the practice of feeding a small amount of hydrogen into an internal combustion engine (ICE) through the air intake will result in a higher power output. This is due to a combination of the reaction of hydrogen with the atomic makeup of the fuel as well as the higher temperature flame that results from burning the hydrogen. The higher temperature promotes a more complete burn of the fuel in the cylinder and passes less waste fuel off to the catalytic converter. The idea here is that an ICE can create the same amount of power using less fuel when a PHI system is used because there is a more complete combustion of the fuel.
Our plan is to research partial hydrogen injection, build an electrolyzer, and test the performance of an ICE with and without assisted combustion. Our hope is that efficiency will increase.
Problem Definition
Internal combustion engines do not burn all of the fuel that is injected into the cylinders prior to ignition. As a result, these engines are not as efficient as they could be.
Background Research
Water electrolysis is one of the many ways to produce hydrogen and is done so by placing two electrically conductive solids (electrodes/plates) with opposing charges in a hydrogen rich, electrically conductive medium and passing a current from the positive to the negative electrode (see Figure 1 on pg.11 for diagram). The main components of the electrolyzer are the electrodes, the electrolyte (conductive medium), the containment vessel, and the power supply used to apply the electric current. It is important to note that the housing, or containment vessel, must be an electric insulator. Hydrogen production can be increased two ways, one of which is simply increasing the current applied to the electrodes. Another approach is to align electrodes in series such that their polarities are like so: [+n-n+n-n+…] where n represents an electrode with no charge (neutral). Neutral plates divide the total available voltage applied to the system and help to decrease the amount of heat created in the system. The number of neutral plates is based on the overall voltage applied to the system; one neutral plate per 2.3V. A system using 2.3V would not need any neutral plates. These two approaches can be combined to achieve optimum performance.
From an efficiency standpoint, it is desired that the system provide as little electrical resistance as possible. The reason for this can be illustrated using the equation V=IR, where V is voltage, I is current and R is resistance. Current is a set constant based on the desired hydrogen output and resistance is another constant governed by the architecture of the system. That means that voltage has to yield to the product IR and will increase with the increase of I and/or R. The desire for a low voltage may be demonstrated using another equation P=VI, where P is power and V and I are as previously noted. In short, decreasing the resistance will decrease the overall power needed to run the system while maintaining the same hydrogen output.
Modern water electrolysis for use in PHI systems employs the use of corrosion resistant electrode materials. Stainless steel is a common material used in less expensive systems, but has a few drawbacks. Over time, the corrosion of the electrodes leads to high concentrations of hexavalent chromium in the water/electrolyte solution, an extremely toxic carcinogen (http://www.hhogenerator.com, 2009). To avoid this, some manufacturers have moved to using titanium electrodes. However, some research shows that the hexavalent chromium only leeches out of the surface of stainless steel electrodes for a short time. Leeching stops after a period of use known as the conditioning period and may take up to a week of continuous operation to complete. We will be using 316L or 320L stainless steel in our cell, as cost is a concern.
In general, it is desired to use a non-caustic electrolyte. Caustic electrolytes can end up in the engine and cause premature wearing of engine components. The byproduct of the chemical reaction is also a concern. There are many things that can increase the conductivity of water, but will produce other pollutants during the electrolysis process. Much of our research will focus on determining which solution is appropriate. We’re not just trying to make the ICE more efficient, we’re trying to do it without introducing other toxins to the atmosphere.
The Need
Today’s consumers are being met with an increased need to concern themselves with fuel efficiency from an economic stand point. Solutions to this problem can include driving less, using public transportation or even purchasing a more fuel efficient vehicle. For some, these are not practical solutions. They need their current vehicle to be more fuel efficient.
In recent years, there has been a growing interest in using hydrogen gas to increase fuel efficiency. The general understanding is that when hydrogen is introduces fed into the air intake of an internal combustion engine it helps to burn more of the fuel that is injected into the cylinders. The end result is a cleaner burn (reduced emissions) and a higher power output.
The Objective
The driving force behind this project is our desire to investigate how mixing hydrogen with the fuel in an internal combustion engine will effect the performance.
The Work Plan (Methods and Evaluation)
The project will begin with researching of the current technology. This should take about 4 weeks and most of this research will be based on the electrodes and electrolyte solution, as they are the backbone of the system. Once we’ve gained a strong understanding of the existing systems, we will spend a two weeks brainstorming and designing our own system. Following this will be the experiment design and testing of the system. The remaining time will be spent analyzing the data, writing the report, and preparing the final presentation. A Gantt chart is provided in Appendix B to help display the work flow.
The Risk
The analysis of this system will involve the production of hydrogen gas and handling gasoline. The hydrogen will be produced and injected into the air intake at atmospheric pressure. The only time hydrogen is compressed will during the compression stroke of the engine. The ignition of the hydrogen will be in a controlled environment (the piston) where the energy from the expanding gasses can be converted directly into kinetic energy.
Hydrogen production of 1 lpm at atmospheric pressure poses almost no hazard, as any hydrogen released to the atmosphere will quickly rise and dissipate into the air. This rapid dissipation will result in concentrations well below 4% hydrogen.[1]
Gasoline vapors have a higher density than air and will fall to the ground where they collect if the area is not properly ventilated. In the presence of an ignition source, dense gasoline vapors can ignite and present hazards. In an effort to eliminate the collection of these vapors, experiments will be conducted in a way that ensures that all vessels containing gasoline are sealed. In the event of a gasoline spill, the experiment will be aborted and attention will be turned to cleaning and ventilating the contaminated area.
Potassium hydroxide and sodium hydroxide are two very possible candidates for electrolyte. Both of these strong alkaline bases and can burn the skin or make one blind at high enough concentrations. Any handling of the electrolyte solution will be conducted wearing appropriate eye and skin protection.
Our electrodes will be made of either 316L or 320L stainless steel. To address the concern of hexavalent chromium leeching into the electrolyte solution, all waste electrolyte solution will be bottled, labeled, and disposed of according to OSHA regulations.
Team Qualifications
See Appendix A for resumes.
Justin Bruyn
- Manufacturing Industry (1 year)
o Created detailed AutoCAD diagrams of machines and machine setups.
o Recorded and analyzed tested data for new machine setups.
o Designed one off machine modifications to improve production quality.
- Skilled Mechanic
o 2 years of training at Newburgh Free Academy High School (Newburgh, NY)
o 1 year of experience in industry
Andrew Cammorata
- AUV Industry (1 year)
o Solidworks: Designed AUV parts and systems.
o Assembled AUV's and troubleshouted design flaws with a design/build team.
o Tested AuV's in the ocean.
- Mechanic
o Self taught and apprentice at Norm's Automotive Service (Hanover, MA)
o Custom Car Design and Maintenance, specializing in Hot Rods.
Myles Moore
- Proton Exchange Membrane Hydrogen Fuel Cells (1 year)
o Performed various material property/behavior investigations on internal fuel cell components
- Building Automation Industry (1 year)
o Commissioned building control systems
o Troubleshot system errors
o Designed computer interface used for communicating with the control systems
- Skilled Machinist
o 4 years of training at Old Colony Regional Vocational Technical High School (Rochester, MA)
o 1 year of experience in industry
Chris Sandini
- LED Industry
o Solidworks: Designed custom LED signs for customers.
o Designed an automated soldering machine.
o Surface soldering, PCB desgin and troubleshooting.
- Computer Technician
o Built custom computers, advanced skill level in overlocking/tweaking computers
o EASYtech at Staples ~2 years.
- Web and Multimedia Designer
o Highly Experienced in Flash, Dreamweaver, and Photoshop.
Project Budget
The project budget is not expected to exceed $200. The group already had possession of most of the materials. A few thermocouples, pressure gages, hoses, and gradated cylinders will need to be purchased.
Project Future (What do you see happening with this?)
Partial hydrogen injection (PHI) is something that has been on the back burner of the alternative energy field since before the 1970’s. There have been many attempts to couple on-board steam reformers with combustion engines, but “the major drawback of this process is its complexity. The operation of the steam reformer at a specified temperature, followed by shift conversion at a specified lower temperature, followed by water separation presents temperature and flow control problems that were considered to be too complex for an automotive application.” (Cerini, 1974) As a result, much attention has been turned to water electrolysis for hydrogen production.
Having the hydrogen mixed with the fuel causes almost 100% of the fuel injected into the cylinder to be burned. These systems could eliminate the need for a catalytic converter while increasing fuel efficiency at the same time. PHI is a truly remarkable way to use our petroleum resources more responsibly.
If our discoveries regarding PHI lead to something that we can see being a viable fuel supplement, this project could be carried over into the senior design project for further investigation.
Bibliography
Cerini, J. H. (1974). On-Board Hydrogen Generator for a Partial Hydrogen Injection Internal Combustion Engine. New York, New York: Society of Automotive Engineers, Inc.
http://www.hhogenerator.com. (2009, Dec. 28). Retrieved from http://www.hhogenerator.com: http://www.hhogenerator.com/hho-and-the-energy-market-olympic-hydrogen-ti-hho-generators/
Appendix A
Appendix B
Figure 2: Gantt chart list
[1] Hydrogen is only combustible at concentrations from 4% to 74.2% by volume.