|MadSci Network: Engineering|
Greetings: I have read the Mercury Marine web pages at the following URL and I could not find any reference to hydrogen peroxide injection into their engines so Iíll have to make an educated guess to answer your question: http://www.mercurymarine.com/mercuryhome/ Combustion, or burning, is a rapid, self-sustaining chemical reaction that releases a significant amount of heat. Examples of common combustion processes are burning candles, forest fires, log fires, the burning of natural gas in home furnaces, and the burning of gasoline in internal combustion engines. For combustion to occur, three things must normally be present: a fuel, an oxidizer, and an ignition stimulus. (An exception is hypergolic combustion used in space vehicles, in which a fuel and an oxidizer spontaneously react on contact without the need for an ignition stimulus.) Fuels can be solid, liquid, or gas. Examples of solid fuels include wood, and coal. Liquid fuels include gasoline and kerosene. Propane and hydrogen are examples of gaseous fuels. Oxidizers can also be solid (such as ammonium perchlorate, which is used in space shuttle booster rockets), liquid (such as hydrogen peroxide), or gaseous (such as oxygen). Air, which contains 21% oxygen, is a particularly common oxidizer. Electrical sparks or glow plugs are examples of an ignition stimulus. Letís review the operation of typical 4 stroke and 2 stroke internal combustion engines: Stroke 1: the oxidizer (air) and fuel (gasoline) are drawn into (or injected into) a cylinder during a piston down stroke. Stroke 2: The fuel/oxidizer mixture is compressed during a piston up stroke Stroke 3 : The spark plug ignites the fuel/oxidizer mixture driving the piston down in a power stroke. Stroke 4: The rising piston drives the combustion by products completely out of the cylinder during an upstroke The advantages of the 4 stroke engine are that the intake, compression, ignition/power and exhaust cycles are separate events that are efficiently completed, each having about 25% of the total time of operation. The disadvantage is that 2 rotations of the crankshaft are required for each power stroke. Four stroke engines typically have several cylinders to enable a smooth running engine, particularly when operated at low revolutions per minute (RPM). Small, compact, air cooled internal combustion engines often use a 2 stroke process. Stroke 1: On the upstroke a fuel/air mixture is compressed along with some residue exhaust gas from the previous cycle. Stroke 2: The spark plug ignites a fuel/air mixture providing a power stroke which also exhausts the combustion products at the end of the stroke. The advantage of the 2 stroke engine is that a power stroke occurs for every rotation of the crank shaft. The disadvantages are incomplete fuel/oxidizer intake and combustion exhaust processes due to the short time (a few % of the total operation) available to perform these functions. To make 2 cycle engines more efficient with less pollutants in the exhaust, an optimum fuel/air mixture can be quickly inserted into the cylinder with a high pressure fuel injector. This has improved 2 stroke engine power and efficiency. However, because air is composed of 78% nitrogen and only 21% oxygen (the oxidizer) the fuel/oxidizer mixture is still far from optimum, particularly with the 78% of unwanted, pollution causing nitrogen in air. By injecting an efficient, non polluting oxidizer, such as hydrogen peroxide (H2O2), into the cylinder along with the fuel/air mixture, additional oxygen is made available for combustion process and water (H2O as steam) is a major by product from the added process. The steam can also remove heat from the cylinder reducing the need for cooling of the engine. Hydrogen peroxide could improve the operation of 4 stroke engines but the gain is not nearly as great as would be obtained with 2 stroke engines. Here in California many industries cannot not use air in there combustion processes and liquid or gaseous oxygen are used in place of air to greatly reduce air polution. However, these are typically fixed sites and not vehicles. Hydrogen fueled vehicles are also being tested in many states. Hydrogen peroxide (H2O2) is an interesting chemical that is now being used to clean up a number of polluting processes here on planet earth. You can read about some of these applications at the following web site: http://www.h2o2.com Best regards, Your Mad Scientist Adrian Popa
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