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Old 17-02-2013, 03:18 AM
maxc maxc is offline
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Join Date: Feb 2006
Posts: 59
Default Re: Post Combustion injection of water

Quote:
Originally Posted by Richard L View Post
OK, it is a thermodynamic topic. Change of Enthalpy within the closed system (combustion chamber). There are no magic in this.

Enthalpy is a measure of the total energy of a thermodynamic system. It includes the internal energy, which is the energy required to create a system, and the amount of energy required to make room for it by displacing its environment and establishing its volume and pressure.

It is not a free energy, you need extra heat to create extra expansion work.

Engine can only produce 30% mechanical work. The other energy is released via the exhaust, cooling system and radiated.

You can recover a large portion of heat energy with the following methods:

1. A turbocharger to increase the effective compression ratio.
2. Water injection/Steam injection into the combustion chamber to absorb any excessive heat that may damage the engine.
3. Stop water circulation to the radiator.
4. Insulate the entire engine so heat is retained internally.

In fact it is better to introduce water droplets at a lower state of enthalpy, allow it to absorb more heat from the combustion process. This is not as simple as it seems. If you are injecting steam or water droplet into an unstressed engine, you will probably loose power. For this to work, the engine has to be in great stress, ie high compression ratio (effective compression), high EGT, ignition timing approaching MBT. Only then, you will see good mechanical gain with water injection . Resulting in better MPG.

THIS IS "NOT" NEW. Do some research on the SAE papers. I remembered reading a project done on a heavy duty diesel engine installed in a bus. It was done almost thirty years ago in Japan, result was very positive but it did not catch on at all. This topic has been studied many time over the years.
there are over 10000 patants on steam injection oil company's dont like it. as you would say red tape.

Last edited by maxc; 17-02-2013 at 03:20 AM. Reason: spelling
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