water injection into the EXHAUST
11-19-2006, 04:28 PM
#18
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Did not follow the thread for some time, just something to clearify:
I am aware that the turbo works due to the heat of the exhaust gases so injecting water into the crossover seem strange at first which would cool down the exhaust gas and do the opposite of what I was hoping to achive. My idea was to inject water only for a short time during the spool-up of the turbo and use the heat stored in all the tubing. Exhaust temp would probably drop too but if metered correctly most likley not much. The water would evaporate, cooling the tubes, a bit the exhaust gases and the turbo. Due to water going into steam (expansion) I hoped aiding spool-up. During testing it turned out to have no noteable effect. So it was not worse too. I did not datalog any numbers and had to rely on my own impression only.
I am aware that the turbo works due to the heat of the exhaust gases so injecting water into the crossover seem strange at first which would cool down the exhaust gas and do the opposite of what I was hoping to achive. My idea was to inject water only for a short time during the spool-up of the turbo and use the heat stored in all the tubing. Exhaust temp would probably drop too but if metered correctly most likley not much. The water would evaporate, cooling the tubes, a bit the exhaust gases and the turbo. Due to water going into steam (expansion) I hoped aiding spool-up. During testing it turned out to have no noteable effect. So it was not worse too. I did not datalog any numbers and had to rely on my own impression only.
11-19-2006, 05:21 PM
#20
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The extra volume that the water to steam transition requires and its cooling effect on the hot (fast) exhaust gas work against each other and without a quantitative thermodynamic analysis or empirical data it is difficult to say which mechanism “wins”.
Taking some of the heat out of the tubing for a brief period (spool-up only) may be a good idea with the right amount of water. Once the desired boost has been reached the turbocharger has more than adequate capacity to keep up the boost and heat up the tube again.
For those afraid of converting water to steam in the exhaust, remember that the two main combustion products are CO2 and H2O. When starting from cold there actually is a fair amount of water in the X-over pipe, as I am sure most who have taken the WG off has experienced.
Laust
Taking some of the heat out of the tubing for a brief period (spool-up only) may be a good idea with the right amount of water. Once the desired boost has been reached the turbocharger has more than adequate capacity to keep up the boost and heat up the tube again.
For those afraid of converting water to steam in the exhaust, remember that the two main combustion products are CO2 and H2O. When starting from cold there actually is a fair amount of water in the X-over pipe, as I am sure most who have taken the WG off has experienced.
Laust
11-19-2006, 06:13 PM
#21
Temprarily Banned per IB
Aside from everything else brought up so far, I'd just like to add one last tidbit. It would take some pretty high dollar heat/corrosion resistent plumbing to get a nozzle in there that would stand up to the heat/pressure.
11-20-2006, 01:17 AM
#22
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Actually, the volume you gain from the evaprated water is about five times less than the volume you lose from the resulting less exhaust heat. This is a net loss of volume to drive your turbine (not to mention the heat loss).
If this was not true, WI in your intake would not work, 'caus it's the other way around.
Think about it.
If this was not true, WI in your intake would not work, 'caus it's the other way around.
Think about it.
11-20-2006, 02:37 AM
#23
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Originally Posted by TurboTommy
Actually, the volume you gain from the evaprated water is about five times less than the volume you lose from the resulting less exhaust heat. This is a net loss of volume to drive your turbine (not to mention the heat loss).
If this was not true, WI in your intake would not work, 'caus it's the other way around.
Think about it.
If this was not true, WI in your intake would not work, 'caus it's the other way around.
Think about it.
It is not the volume alone that drives the turbine it’s the density, volume per unit time and speed (very likely density times volume per unit time times speed squared) that provides the power to the turbine.
What is proposed here is momentarily extracting some heat from the pipe for turbo spool-up. This does cool the exhaust gas somewhat, but certainly not as much as if all the latent heat was taken from the exhaust gas. When there is plenty of heat available the pipe is heated up again.
Laust
