Mercedes Power Unit Hardware & Software

[hurril]

It is probably more interesting to increase the flow rate than it is to increase the pressure past a certain point.

[Edis]

You have to develop that pressure somewhere. Something has to generate that 9 bar of pressure if you insist that's the suction pressure of the pump. It could be from heating the water, but that is not likely at all from 1 bar to 9 solely from heating. It would not be desirable.
But i don't think there is a need for such high pressure as the physical properties of the water wont change much.
Also you are looking at heavier construction with containing 10 bar pressure as opposed to 3 bars.

The maximum pressure for the cooling system is 3.75 bar. The pressure is created by the expansion of the water and gas within the closed volume of the cooling system. In a racing application the expansion tank can also be pre-pressurized with compressed air.

https://www.youtube.com/watch?v=jSG37vjU3S4

7.5 Coolant header tanks :
Any header tank used on the car with a water based coolant must be fitted with an FIA approved pressure relief valve which is set to a maximum of 3.75 bar gauge pressure, details of the relief valve may be found in the Appendix to the Technical Regulations. If the car is not fitted with a header tank, an alternative position must be approved by the FIA.

[gruntguru]

You have to develop that pressure somewhere. Something has to generate that 9 bar of pressure if you insist that's the suction pressure of the pump. It could be from heating the water, but that is not likely at all from 1 bar to 9 solely from heating. It would not be desirable.
But i don't think there is a need for such high pressure as the physical properties of the water wont change much.

Agreed. I don't actually believe the systems run at 10 bar or that the pump inlet is at 9 bar. Just saying that a pressurised water system does not use the pump to generate the pressure.

BTW. 9 bar water boils at 175*C. The engines don't run that hot but the boiling point in a cooling system needs to be many degrees higher than operating temperature to avoid vapor bubble formation at water jacket hot spots or cavitation at points high velocity/acceleration.

[PlatinumZealot]

You have to develop that pressure somewhere. Something has to generate that 9 bar of pressure if you insist that's the suction pressure of the pump. It could be from heating the water, but that is not likely at all from 1 bar to 9 solely from heating. It would not be desirable.
But i don't think there is a need for such high pressure as the physical properties of the water wont change much.
Also you are looking at heavier construction with containing 10 bar pressure as opposed to 3 bars.

The maximum pressure for the cooling system is 3.75 bar. The pressure is created by the expansion of the water and gas within the closed volume of the cooling system. In a racing application the expansion tank can also be pre-pressurized with compressed air.

https://www.youtube.com/watch?v=jSG37vjU3S4

7.5 Coolant header tanks :
Any header tank used on the car with a water based coolant must be fitted with an FIA approved pressure relief valve which is set to a maximum of 3.75 bar gauge pressure, details of the relief valve may be found in the Appendix to the Technical Regulations. If the car is not fitted with a header tank, an alternative position must be approved by the FIA.

So just normal pressures then. I think that is the pressure on my radiator cap.

[wuzak]

A radiator that can handle >10 bar wold be some piece of work. And for what thermal advantage? At 10 bar (gauge) the temp of boiling water is 184°C. Just what you don't want for a cooling device.

Why not? There are benefits to running a hotter cooling medium.

Yes, but there can be side effects.

In the late 1920s and early 1930s the USAAC engineering division produced a single cylinder design in the "hyper" program. The aim was for 1hp/cubic inch and 1hp/lb.

One of the ways they tried to achieve this was to raise the coolant temperature to 300F (149C).

And it worked, the heat rejected to coolant was reduced, which would mean a smaller radiator and lower drag.

Unfortunately the heat that was no longer going into the coolant was now going into the oil. Which meant a larger oil cooler was required, so any drag benefits from the reduced coolant radiator was offset by the losses from the larger oil cooler.

In current F1 terms I guess the goal would be to also raise the oil temperature to limit heat transfer there and ensure that more heat is either used to drive the crankshaft or exit in the exhaust for increased potential energy recovery in the turbine.

[ringo]

So you would have to have an oil engineered to give the tight lubrication and viscosity characteristics at higher temps to carry all that heat away.

Is there any kind of insulation involved with the airflow channels of the cylinder head?
Since we are taking about high block temperatures it makes sense to keep that away from the charge air coming in.

[godlameroso]

We know you can coat parts to your heart's content, but the main block still has to be made from aluminum. The problem with aluminum is the low fatigue point. 150-160c is pushing it as far as bare aluminum is concerned.

[Edis]

You have to develop that pressure somewhere. Something has to generate that 9 bar of pressure if you insist that's the suction pressure of the pump. It could be from heating the water, but that is not likely at all from 1 bar to 9 solely from heating. It would not be desirable.
But i don't think there is a need for such high pressure as the physical properties of the water wont change much.
Also you are looking at heavier construction with containing 10 bar pressure as opposed to 3 bars.

The maximum pressure for the cooling system is 3.75 bar. The pressure is created by the expansion of the water and gas within the closed volume of the cooling system. In a racing application the expansion tank can also be pre-pressurized with compressed air.

https://www.youtube.com/watch?v=jSG37vjU3S4

7.5 Coolant header tanks :
Any header tank used on the car with a water based coolant must be fitted with an FIA approved pressure relief valve which is set to a maximum of 3.75 bar gauge pressure, details of the relief valve may be found in the Appendix to the Technical Regulations. If the car is not fitted with a header tank, an alternative position must be approved by the FIA.

So just normal pressures then. I think that is the pressure on my radiator cap.

In a normal engine, the relief valve on the expansion tank typically open around 1.5 bar.

We know you can coat parts to your heart's content, but the main block still has to be made from aluminum. The problem with aluminum is the low fatigue point. 150-160c is pushing it as far as bare aluminum is concerned.

The problem is that you start reach annealing temperatures for aluminum alloys from about 150-160 degC, although there are aluminum alloys that can withstand 200-250 degC too, so this can be solved with material selection. Running such high temperatures will cause other problems though, like problems with lubrication of the cylinder, even higher piston temperatures, knock and loss of volumetric efficiency.

[wonk123]

So you would have to have an oil engineered to give the tight lubrication and viscosity characteristics at higher temps to carry all that heat away.

.

I was talking to Lake Speed about this in NASCAR, here is an article where he discusses it
http://www.enginelabs.com/engine-tech/o ... car-rules/

[Brian Coat]

Yes.

NASCAR has special oil cooling challenges because they spray a LOT of oil onto the (highly marginal) valve springs in order to cool them. This is done via a spray rail fabricated into the rocker cover.



F1 challenges are in different league but NASCAR is not as simple as it looks.

[hardingfv32]

I would say that temperature of the oil going to bearings with specific clearances could be well controlled. The oil being used to spray springs and pistons just absorbs heat and returns to the supply system where it is cooled. This is not a big issue for the oil as long as the cooling system operates under constant conditions. This is not the case in a NASCAR drafting pack where the fixed oil cooling system operates under restricted air flow for periods of time. They make the choice to have the correct oil temp when running free of the pack.... it is a compromise that the driver must manage.

I am not aware of any chemical that makes oil a better heat transfer medium. There could be some property difference between base oils but nothing that applies across all base formulations.

Brian

[jonas_linder]

Why are you guys not discussing anything closer related to the actual PU? They just spent 5 tokens!

So HAM started with new components in each of the FP. I find it interesting that HAM didn't take any new energy storage or control electronics (or maybe he took one of each?)! Is this an indication that they might want to spend future tokens in these areas (HAM and ROS are only on their 4th of each)? Or are they mature technologies that won't get any updates?

[nevill3]

Does anybody know if the customer teams have the new spec engines yet? I remember that Williams refused the new engines at one point last year but if the customers were ready for a new engine then surely the new spec has to be supplied.

In the original list of the power units used the rest of the customer teams are still on three ice each

[PlatinumZealot]

Only merecedes has the new spec.

[RicME85]

The other teams aren't at the right point in their usage cycle to have the new parts apparently