Heatsinks maybe?

[xpensive]

For sminkle: Interesting statement, short but somehow affirmative, but please define "low quality"?

[PlatinumZealot]

High quality energy is energy that you can use to do more work with.

E.g You can have a bath tub of 50 gallons of water at 60*C Compared to 10 gallons of high pressure water at 300*C.

Just as an estimate lets pretend they have the same amount of energy (can't bother to use my steam table lol ) You can do more work with the hotter water at 300*C.

Steam is a very high quality of energy.. warm water is not a high quality of energy.. you can't do much with work with it.

Some forms of energy such as electricity are of high quality.
Low quality is like the heat coming out of your computer.

Nature is good as using low quality energy though it takes time. The ambient air temperature is used to evaporate water that then turns to clouds then turns to rain..which we can harness the kinetic energy of to make electricity.. Same for winds and waves..

It's hard to explain for me.. but generally high quality energy is one that you can turn into other forms of energy easily. IT can do more work.

The radiator water heat loss might be 300KW.. but the state of the water and the temperature of it might not be high enough to do useful work.
You will end up with a system of very low efficiency.

That is why BMW used the exhaust pipes for heat to make superheated steam in the BMW turbo steamer.

Well I don't know what the temperature of the F1 radiators are though maybe 80 to 100*C ? And I have been hearing of this thing called a thermoelectric i think it is like (the reverse?) of the peltier.

[xpensive]

Depending on the temp and volume of the cooling-air, I was thinking of boosting the energy-quality with a compressor?

[DaveKillens]

When it all has to end with convection to the passing air, one way or the other, the following numbers might be of use.

With an engine output of 500 kW and 25% efficiency, total power would be 2000 kW, meaning 1500 kW is wasted heat.
How much dissipated through the cooling circuit? Let's say 300 kW (300 kJ/s), for the sake of argument.

At 50 m/s (180 km/h), with 5 kg/s of 25C air passing through at a density of 1.2 kg/m^3 and thermal capacity of 1.0 kJ/kg*K, to exit the same air at 85C, you would need a radiator inlet area of some 0.08 m^2, or say two ducts of each 20x20 cm.

Aerodynamic powerloss, P=Cv*A*Rho*v^3/2, depends on the resistance of duct and radiator, but with a Cv of 0.6, you will lose about 15 kW (20 Hp) through those ducts at 300 km/h.

I need to go back to school...

But this post touches on something relevant. A Formula One engine will generate a fixed amount of heat. No matter what the cooling type or materials, in the end a certain amount of air has to be used in the final act of removing the heat. And this amount of air is determined by the amount of heat the engine generates. So even if you designed and installed a radiator of the highest heat transfer properties, it will require a specific amount of air to carry away the heat. Aluminum or copper, you're still going to require a lot of air.

Well I don't know what the temperature of the F1 radiators are though maybe 80 to 100*C ?

Water boils at 100 degrees C. That's at seas level. If you pressurize it (which they do), then the boiling point of water is raised. Thus, the radiator water temp is well above 100 degrees C.

[PlatinumZealot]

I was talking about the surface of the radiator (I measured it from my car and just made a guess of the F1 radiator). I don't know how hot the water in the coolant passages is though.But yeah it is definitely above 100*C.
Yeah that is more is more important.

I guess you can find the pressure of the system and use a steam table to get the boiling point.

I need to go back to school too.

[xpensive]

I guess that if you can bring the water-temperature higher, you should be able to utilize the passing air better.

If you in the above example assume an air exit-temp of 100C rater than 85, everything else equal, size of the ducts should be reduced from 0.08 to 0.06 m^2, or 25%, which would reduce drag-losses with 5 Hp.

[PlatinumZealot]

I need to go back to school...

But this post touches on something relevant. A Formula One engine will generate a fixed amount of heat. No matter what the cooling type or materials, in the end a certain amount of air has to be used in the final act of removing the heat. And this amount of air is determined by the amount of heat the engine generates. So even if you designed and installed a radiator of the highest heat transfer properties, it will require a specific amount of air to carry away the heat. Aluminum or copper, you're still going to require a lot of air.

=D>

Yes.. this is the key!!

http://www.f1technical.net/features/250

This article reminds us that the amount and the speed of air in the radiator openings depend on the size and shape of the opening and the things behind it.

So even if we use copper as some one posted before, and we use a smaller opening.. we have to get the amount of air required through that smaller opening. It is going to be hard because of the size of the hole and the local air speed.

Reinforcement From the article:

Moreover, this energy wasteage provides significant challenges when it comes to controlling temperatures. While the heat exchangers on a racing car are extremely efficient, their ability to cool the engine is a function of the 'air-side capacity' - essentially, how big a mass of air you can make flow through the radiator for a given area. This depends, of course, on generating high air velocities in the radiator intake ducts: however, typically, air velocity in the radiator ducts will only be 10-15% of the car's velocity, so even if the car is travelling at 300 kph, the air in the ducts is probably only at 30-35 kph.

[xpensive]

There it is, thanks for bringing that piece up smikle!

Guess my numbers were not that far off actually, when according to the above water and oil cooling are said to be 295 kW, even if the article is referring to 3 liter engines. Cooling water at 120C also makes sense.

The low air-speed, 35 km/h through the radiator at a travelling-speed of 300, I find very difficult to believe though. That would mean either gigantic ducts or an exit-temp of hundreds of C to convey that power, clearly something wrong there.

[riff_raff]

xpensive,

f1 reg's limit the properties of coolants that may be used and the cooling circuit pressures are limited to 3.75 bar.

As for extracting energy from the coolant waste heat flow, a well designed radiator duct does exactly that. The airflow across the heat exchanger core is accelerated as it picks up heat energy from the coolant, and (hopefully) exits the radiator duct at higher velocity than it entered with. Thus providing either downforce or forward thrust.

Regards,
Terry

[xpensive]

Terry,
If i get you right, you suggest that radiators provide propulsion to the F1 car through thermal expansion of cooling-air?

At constant pressure, the volume of a gas is proportional to absolute temperature (Gay-Lussac law), why from 25 to 90C you will have an expansion of (273+90)/(273+25) or 22%. There should be a more efficient way to make use of 300 kW?

Thermal expansion of the exhaust gasses is a completely different matter though, which was earlier debated on:
viewtopic.php?f=6&t=6435&hilit=exhaust+speed

[PlatinumZealot]

I made a radiator in solid works. I just need to read the Tutorials again , I can try to do some sort of simulation. Maybe copper VS aluminum.
Right now i am trying to figure out if it is best to do an external fluid flow or an internal one; either make a side pod or just a simple box around the radiator.. When i get more time i will try to finish it.

I have a few things i want to check like: what if the copper one is 3 times smaller.. how to get a similar air flow in that smaller radiator space.

I dunno.. I going to give it a go, no expert though just trying a thing.

[xpensive]

That should be the point smikle, to minimize the flow of air through the radiator, in other words to heat up the air to highest possible temp, which largely will be decided by the outside temperature of said radiator?

It seems that an air-inlet area much smaller than the cross-section of the radiator, is today's preferred solution. Is it just me, or do the Mercedes-powered cars have smaller inlets than the others?

[riff_raff]

xpensive,

If i get you right, you suggest that radiators provide propulsion to the F1 car through thermal expansion of cooling-air?

Actually, what you really want to do is impart momentum to the cooling air mass flow. And that means increasing its velocity. You want the air discharge to be at a higher velocity than it entered the duct at. Think of a radiator as a crude form of jet engine.

As you noted, it's not the most efficient method of converting that waste heat energy. But it is by far the simplest, requiring no moving parts. The biggest concern with most radiator installations is to not incur a drag penalty. There are also other concerns, such as discharging the airflow in such a manner as to not upset the airflow to other parts of the body work.

Here's a link to a good (but old) tech paper on the subject:
http://ntrs.nasa.gov/archive/nasa/casi. ... 093155.pdf

Regards,
Terry

[ISLAMATRON]

So what is the answer to this fundamental question... Why dont the teams use this copper radiator that would be 1/3 as small(surface area wise) to decrease the drag penalty of the side pods? Of course they would have to place it lower for CG reasons.

But just because the copper radiator is 1/3rd as small it would still need the same amount of airflow to dissipate the same amount of heat, and the volume of the airflow is what dictates the size opening of the sidepod opening.

My heat transfer is really rusty so please anybody confirm or correct.

[riff_raff]

Islamatron,

I'm like you. I just posed the question because I am not smart enough to answer it myself.

However, I don't necessarily agree that the copper core would have 1/3 the volume of the aluminum core. And it would definitely not require the same mass airflow as an aluminum core since the heat transfer rate to the airflow would be much more efficient with the copper core. The required mass airflow is a function of the temperature rise in the airflow across the core. A copper core would require less total surface area to transmit a given amount of heat energy, since it would do so more efficiently.

The other things to consider are that the smaller copper core could be packaged in the chassis to produce a lesser overall polar MOI. The copper core may also require a smaller total volume of coolant in the circuit, thus reducing weight. A set of F1 radiators take up a lot of space, can easily weigh 30 or 40 pounds each when full of coolant, and are normally located far off of the cars polar axis. So making them more compact and locating them closer to the car's neutral axis would seem to be very desirable.

Here's the tricky thing to remember about heat transfer in liquid-to-air heat exchangers- the heat transfer only really takes place at the very thin boundary layer flows occurring along the walls of the tube and fin passages. That's why increasing the total surface area of the core is so important. And even more importantly, maximizing the heat transfer rate across the tube wall by using a high thermal conductivity material.

Regards,
Terry