Bike's away for winter, anyone know a good place to get my head ported?

[Arttu]

20 hours ago, Gixer1460 said:

No empirical evidence here but I suspect the 'instant' cooling effect is real but the minimal power increase is down to the water taking up volume in the cylinder whilst providing no combustibles. The air density may increase slightly due to the cooling and so aid with detonation but I suspect any added fuel serves hardly any 'useful' purpose other than a bit more cooling / lowering the AFR even further. Carrying useful quantities of water mix will pose problems and risk of running out whilst at high boost could prove terminal - maybe good at the track where levels can be monitored but for a road bike even with the inherent impracticalities an air 2 air IC alone or with the use of E85 must be a better solution long term. I know I could run my system with pump piss up to around 1 bar boost very safely but using 2+ bar boost, I must use decent fuel - C16 race fuel or similar - easy choice, as nothing is free, there are always trade off's!

The cooling effect is definitely real but even that can be easily over estimated. If you have a temp sensor downstream the injection nozzle it will get cooled by water mist and therefore show lower readings than actual air temp. I guess in-cylinder cooling reduces cylinder pressure during power stroke which then more or less cancels benefits of improved intake air density. Like you said water vapor also replaces some air in intake charge but I think that has quite minor effect in the end.

Actually having enough water on board isn't that big problem in street use. If you use mainly water and keep injection flow reasonble the water consumption is pretty low. I have about 1.5 liter tank and it lasts for several hundreds of kilometers even when riding moderately hard. On cricuit track it was enough for about an hour of track time if I recall correctly. But I still have some fail safe mechanisms in my system so if I run out of water or the nozzle gets blocked the boost control gets disabled and boost drops to base spring pressure.

[Madb]

slightly off topic but Could you use LN2 to cool the IC instead of water? Just a thought. 

[Gixer1460]

1 hour ago, Madb said:

slightly off topic but Could you use LN2 to cool the IC instead of water? Just a thought. 

I'd guess carrying a cylinder of liquid N2 would pose significant risk to life, on a bike, outweighing its potential cooling benefits - no one ever died through a punctured IC in a crash LOL! But no - nothing to stop you trying 

[Arttu]

4 hours ago, Madb said:

slightly off topic but Could you use LN2 to cool the IC instead of water? Just a thought. 

Yes, should work. But if you are going to see the effort to have a bottle of liquid gas on the bike I think N2O would be more efficient.

[rerb]

On 12/3/2021 at 5:25 AM, Madb said:

slightly off topic but Could you use LN2 to cool the IC instead of water? Just a thought. 

i've been thinking about this more and more, next semester I'm taking a thermodynamics and heat transfer class, maybe it's the perfect project for the final...

[Madb]

Now that would be Cool.  Keep us informed. 

[Arttu]

On 12/5/2021 at 4:10 AM, rerb said:

i've been thinking about this more and more, next semester I'm taking a thermodynamics and heat transfer class, maybe it's the perfect project for the final...

Just out of curiosity I did some brief feasibility calculations.

Let's assume we have a 300hp engine setup and we want to cool intake charge from 100°C down to 0°C.

For 300hp the air mass flow would be about 0.25kg/s. Thermal capacity of air is 1 kJ/(K*kg) So cooling that by 100°C releases 25kJ of energy per second.

Liquid nitrogen boils at -196°C and it's evaporation heat is about 200 kJ/kg. Thermal capacity is pretty much the same than for air, 1 kJ/(K*kg). So boiling 1 kg of liquid nitrogen and heating it up to 0°C takes about 400kJ of energy.

When we put all this together we find out that cooling the intake air will consume 25kJ / 400kJ/kg = 0.0625kg of liquid nitrogen per second. So 1kg would last about 16 seconds. Pretty much what I expected, not very practical for street use. But could work for drag racing or some other short duration use.

[Gixer1460]

Yeah - that's what I was about to type but the Casio had a flat battery  Man you are waaaaay too smart!

[rerb]

16 hours ago, Arttu said:

Just out of curiosity I did some brief feasibility calculations.

Let's assume we have a 300hp engine setup and we want to cool intake charge from 100°C down to 0°C.

For 300hp the air mass flow would be about 0.25kg/s. Thermal capacity of air is 1 kJ/(K*kg) So cooling that by 100°C releases 25kJ of energy per second.

Liquid nitrogen boils at -196°C and it's evaporation heat is about 200 kJ/kg. Thermal capacity is pretty much the same than for air, 1 kJ/(K*kg). So boiling 1 kg of liquid nitrogen and heating it up to 0°C takes about 400kJ of energy.

When we put all this together we find out that cooling the intake air will consume 25kJ / 400kJ/kg = 0.0625kg of liquid nitrogen per second. So 1kg would last about 16 seconds. Pretty much what I expected, not very practical for street use. But could work for drag racing or some other short duration use.

True, that does add quite the challenge for a successful model...

Now what about dry ice? Assuming I'm at the track, filling a container with dry ice and plumbing it Into the intercooler core then out to atmosphere, having either a blower fan or some sort of venturi to pull the dry ice vapor through the core.

It's still a good -109 f when it sublimes, and leaves behind no moisture. I know water based intercoolers can get corroded cores, so this also seems like a plus. It's also less dangerous than nitrogen, and would require less advanced metering and control for a safe and functional result

This idea might be far from a practical, streetable solution, but it would be pretty fun and unique to build... and hopefully get me a good grade

[Madb]

I was thinking of short sprints up the strip and not for road use. I just wondered if anyone has done it on the drag strip. Maybe another First for OSS?

Or for Long distance...... Add a trailer thingy.  yeah, I know, Me is mad!

[Arttu]

13 hours ago, rerb said:

True, that does add quite the challenge for a successful model...

Now what about dry ice? Assuming I'm at the track, filling a container with dry ice and plumbing it Into the intercooler core then out to atmosphere, having either a blower fan or some sort of venturi to pull the dry ice vapor through the core.

It's still a good -109 f when it sublimes, and leaves behind no moisture. I know water based intercoolers can get corroded cores, so this also seems like a plus. It's also less dangerous than nitrogen, and would require less advanced metering and control for a safe and functional result

This idea might be far from a practical, streetable solution, but it would be pretty fun and unique to build... and hopefully get me a good grade

Sublimation heat of dry ice seems to be 571 kJ/kg so it's more effective per weight compared to liquid nitrogen. But using it effectively might be more tricky. Sublimation should happen inside the intercooler, otherwise you loose the main part of cooling capacity. So you would need some different style cooler which you could fill with the dry ice pellets. Or alternatively you could have an air-to-liquid cooler core, use alcohol as coolant and chill it with dry ice.

[Blubber]

1 hour ago, Arttu said:

Sublimation heat of dry ice seems to be 571 kJ/kg so it's more effective per weight compared to liquid nitrogen. But using it effectively might be more tricky. Sublimation should happen inside the intercooler, otherwise you loose the main part of cooling capacity. So you would need some different style cooler which you could fill with the dry ice pellets. Or alternatively you could have an air-to-liquid cooler core, use alcohol as coolant and chill it with dry ice.

Just add a pellet feeder to your intercooler. Job done