2014 intercooling

[aral]

As far as I can ascertain, some, if not all the teams use a waterless coolant. Even modern road cars now use this, and is every bit as effective

[trinidefender]

For all of you still arguing about water to air and air to air intercooler a then look at the link. And yes ringo, these numbers do take into account the transmission surface material.

http://www.engineeringtoolbox.com/overa ... d_284.html

And if it was only the end substance than matters when it comes to heat transfer then why do cars use water radiators and not air radiators since they would be much lighter. Also why are additives used to help the water cool better. If what you (ringo) said is true then additive or not the same heat transfer for normal cars would take place but that is simply not true, go and read up about thermodynamics.

[basti313]

go and read up about thermodynamics.

Sorry, but you are so far away from thermodynamics, that this sounds like a joke...

[trinidefender]

go and read up about thermodynamics.

Sorry, but you are so far away from thermodynamics, that this sounds like a joke...

Fair enough, thermodynamics concerns the relationship between heat and other forms of energy. I stand corrected. What I said about heat transfer still stands though.

[PhillipM]

And if it was only the end substance than matters when it comes to heat transfer then why do cars use water radiators and not air radiators since they would be much lighter. Also why are additives used to help the water cool better. If what you (ringo) said is true then additive or not the same heat transfer for normal cars would take place but that is simply not true, go and read up about thermodynamics.

You might want to do some reading yourself, in the turbo system, you are wanting to cool the intake air, to the outside airstream.
For a car engine, you are wanting to cool the metal block, to the outside air. That's a very different system.

That table you linked, for what is relevant is air>aluminium>air in the case of an air/air exhanger, in your water cooled system, it's air>aluminium>water>aluminium>air.
Even your own table shows you that's not going to be as efficient.

As for additives to the water - about the only thing you can add is a surface tension modifier if you have issues with properly wetting parts of the system walls, that doesn't help heat capacity anyway.

[PhillipM]

As far as I can ascertain, some, if not all the teams use a waterless coolant. Even modern road cars now use this, and is every bit as effective

No it's not, and no they don't, otherwise you wouldn't see all the pressurised accumulator/header tanks for the cooling systems all over the cars.

[PhillipM]

There are two auxiliary water pumps (not shown) for the water-air intercoolers. I believe they are electronically controlled.
Maybe Mercedes could be doing this, who knows.

IIRC all ancillaries must be driven directly off the engine - alternator, oil pump, water pump(s), etc. I'd assume that would include charge cooling pumps too unless they don't fall under the engine regulations (although I can't see why not)

[aral]

As far as I can ascertain, some, if not all the teams use a waterless coolant. Even modern road cars now use this, and is every bit as effective

No it's not, and no they don't, otherwise you wouldn't see all the pressurised accumulator/header tanks for the cooling systems all over the cars.

Waterless systems still need header tanks etc. Waterless does not mean no liquids! It just means that the liquid used for cooling is a formulation.

[PhillipM]

Given the only advantage of waterless coolant is a higher boiling point requiring no pressurisation of the header tank, why are they are running header tanks/accumulators with pressure cap then?

[trinidefender]

And if it was only the end substance than matters when it comes to heat transfer then why do cars use water radiators and not air radiators since they would be much lighter. Also why are additives used to help the water cool better. If what you (ringo) said is true then additive or not the same heat transfer for normal cars would take place but that is simply not true, go and read up about thermodynamics.

You might want to do some reading yourself, in the turbo system, you are wanting to cool the intake air, to the outside airstream.
For a car engine, you are wanting to cool the metal block, to the outside air. That's a very different system.

That table you linked, for what is relevant is air>aluminium>air in the case of an air/air exhanger, in your water cooled system, it's air>aluminium>water>aluminium>air.
Even your own table shows you that's not going to be as efficient.

As for additives to the water - about the only thing you can add is a surface tension modifier if you have issues with properly wetting parts of the system walls, that doesn't help heat capacity anyway.

Actually the table shows water to air as having a higher heat transfer rate than air to air. How is it that it is less efficient

[PhillipM]

Actually the table shows water to air as having a higher heat transfer rate than air to air. How is it that it is less efficient

Because it's not water to air. It's water to metal to air. And before that can occure, it's air to metal to water.

So at the end of it all, it's still air>air, but through even more interfaces.

[trinidefender]

Actually the table shows water to air as having a higher heat transfer rate than air to air. How is it that it is less efficient

Because it's not water to air. It's water to metal to air. And before that can occure, it's air to metal to water.

So at the end of it all, it's still air>air, but through even more interfaces.

If you look at the table again you'll realise there is a collom there that gives different heat exchange values through different transmission surfaces. Therefore you point is invalid.

[PhillipM]

If you look at the table again you'll realise there is a collom there that gives different heat exchange values through different transmission surfaces. Therefore you point is invalid.

It's not my point, it was yours, have you actually read *your* table and worked through a simple calc usinhg your very own link? Because it proves the point nicely.

[Lycoming]

Actually the table shows water to air as having a higher heat transfer rate than air to air. How is it that it is less efficient

Because with a water to air intercooler, you aren't going water to air. You're going air to water to air. With some metal in between.

Settle down kids, it's time for second year university thermo/heat transfer.

Ever heard of the circuit analogy of heat transfer? Think of temperature as voltage, heat flow as current and resistance, which is a property characteristic of a specific device.

Your table gives the heat transfer coefficient, h, which is equal to q/(deltaT). Since, from Ohm's law, q = deltaT / R, we have that R is simply 1/h.

Now let's construct our circuits. I'm too lazy to draw the diagrams, but they're simple series circuits. For the air to air intercooler, we have one current source, our heated charge air. Then we have 1 resistor, of value 1/1.4 (I'm using mild steel, it should be aluminum but it doesn't really matter.). And a ground to ambient temperature.

Now for the water to air, we have the same thing, but we have 2 resistors in series. the first resistor is air to water and has value 1/2. the second resistor is water to air, and again has value 1/2. We can think of these two together as one big resistor of value R1 + R2 = 1.

So the water to air has resistance 1, air to air has resistance 1/1.4 = 0.714. Since resistance is inverse of conductivity, lower resistance = better heat transfer. Now in practice, the R value is component specific as it factors in size. The result obtained here just means to maintain the same temperature, the water/air requires a larger rad. Meaning: It's less efficient.

This is something that people who build computers should be aware of. Water cooled computers are thought of as having more cooling power. In actuality, they are less efficient than a standard heatsink. What water cooling lets you do is move the heat off the cpu to a massive radiator mounted elsewhere, or in the case of 1 person I knew, a big bucket of ice water. This radiator is much, much larger than any heatsink that could be practically mounted on the CPU. It's less efficient, it just lets you move the heat to be dissipated someplace far away, where you may gain some advantage, such as having better airflow to it, or by putting it in a place where you can mount a larger rad. That's all there is to it.

tl;dr, you're not using your table properly, and that makes my head hurt.

[ringo]

And if it was only the end substance than matters when it comes to heat transfer then why do cars use water radiators and not air radiators since they would be much lighter. Also why are additives used to help the water cool better. If what you (ringo) said is true then additive or not the same heat transfer for normal cars would take place but that is simply not true, go and read up about thermodynamics.

Additives don't make water cool better. They just change the boiling point and freezing point of the water. They also have anti corrosion and anti scaling properties. For a race car that's going to have all the fluids drained at the end of a race, corrosion is not a problem, engine just has to be flushed out. so water can be used. Freezing isn't a problem either, so glycol is not necessary.

As for you engine question, water takes heat away quicker from the metal of the cylinder walls. The metal is now your limiting factor and not air as in the case of the charged air. The water takes the heat to an area where there is free flow of air to dissipate that heat. If you want to go one better, why not use a metal cooled engine?

What would be even better is metal to air. An air cooled engine like the porsches of old and some of the motor bikes nowadays. Those are more thermally efficient in theory.
But it goes back to the limitation of the location of the engine, can the fins be exposed to cool air? how about the fin design? how much mass of metal is needed to pull heat away from cylinder wall if the air flow is reduced (moving water does this).

As for a good example of an air cooled engine. The porsche 917 CanAm. 1500hp in qualifying. 1,100 in race trim.
go to 4:07

Don't get me wrong, water cooling gives more control, and gives a nice buffer.But it's what at the ends of the chain that will limit you.

Let's work the example and see what is reveals.
edit: Lycoming illustrates it well/