Forced air heating :-(( ??

Hello,

My air-to-water heat exchanger has a large, U-shaped aluminum tube connecting the air intake and the water inlet, with a conical narrowing shape. The total length is estimated to be about 80 cm, and the inlet diameter is approximately 8 cm.
EDIT: Length ~ 60 cm, diameter at the charger approximately 6.5 cm (measured).

It runs mostly directly behind the engine block, and is therefore surrounded by hot air during operation, which heats the intake air.

What is that?????.

For example, in the AFN and ALH models, the comparable part is not only shorter but also made of a relatively well-insulating plastic.

OK, the LLK (likely referring to a heat pipe or similar device) will be located behind it and will remove a portion of the "heat," but I'm still considering wrapping the pipe with insulation to lower the charging temperature.

Can anyone here roughly estimate, in degrees, how much the intake air is heated by passing through the aluminum tube?

Hm, Volkswagen...

Test your isolation and check the result. I don't think you'll find any improvement here, as aluminum usually absorbs heat just as poorly as ABS plastic (or whatever material is normally used).
From my experience with the Golf 4 130PS (ASZ?), I know that the intercooler was designed to be made of either aluminum or plastic (with reinforcing rings) precisely because it might potentially shrink or deform under full throttle. Engine heat and low intake manifold pressure did the rest.
Initially, S3 drivers also had their fair share of problems... you press the accelerator, the turbo kicks in with a *flapp* sound, and the engine runs out of air.

Possibly, someone wanted to prevent this from happening with your 9N, but I'm not explicitly familiar with the engine compartment of your specific model.

Julian wrote:

I think you won't find any improvement here, because aluminum usually absorbs heat just as poorly as ABS plastic (or whatever is normally used). is used).

Hi Julian,

Metals are, as far as I know, all more or less good conductors of heat.

For example, take a look at the CPU cooler in your computer; it's likely made of aluminum.
If ABS were to dissipate heat as effectively (as other materials), heat sinks would definitely be made from it, because it would be cheaper .

I will try to estimate the heat transfer capacity through the pipe based on the surface area and heatsink data (Conrad catalog).
I suspect that adds up to quite a few watts...

Hi!

Yes, the last cooler was made of aluminum, it popped out vertically, and the current one is made of 100% copper... I have only had bad experiences with aluminum coolers in computer cases. They are very common (=cheap!!), but have poor drainage.
Numerical values? Cpu+Al >60°C temperature, Cpu+Cu <40°C

By the way, plastic radiators can only meet the temperature requirements of many manufacturers if they are made of thermoplastics (ABS, for example, is not a thermoplastic), and in this case, they lose many properties that would be beneficial for heat dissipation. It's not working.

Aluminum is significantly stiffer, which is why I believe it was used due to mechanical stress.

Julian wrote:

Yes, the last cooler was made of aluminum, it flew out vertically, and the current one is made of 100% copper... I have only had bad experiences with aluminum coolers in the computer case. They are very common (=cheap!!), but have poor performance.

Well, aluminum isn't actually that bad.

I just found the following values while searching on Google:
Aluminum = 204 W/mK.
Copper = 384 W/mK

So, copper is "only" 88% better than aluminum, but it's about 3 times heavier.
-> The increased weight of a copper heatsink compared to an aluminum one places a correspondingly higher load on the circuit board and the force-transmitting components between the heatsink and the enclosure, especially during vibrations (transport, etc.).

(It's quite generous of VW that the aforementioned pipe is not made of copper ).

But I think that's enough for now as an off-topic comment .

Hi,

Okay, first, a bit off-topic: CPU coolers. The heat generated by the CPU is concentrated in a very small area, which is why copper is essential for current processors. However, essentially, a copper plate is sufficient if it is thermally well-connected to an aluminum frame. This, when properly implemented, offers the best compromise between heat dissipation and low weight.

Regarding the aluminum pipe: Of course, aluminum conducts heat much better than any plastic, but it's questionable how much heat can actually be transferred through it, given its relatively small surface area for its length. A heat exchanger pipe would have internal fins, but even then, it's unclear how much heat can be dissipated to a relatively large volume of air.
The effect is likely minimal at full load, but may be more noticeable at idle in winter, and could even potentially improve comfort.

I once compared some data.

Considering only the specific thermal conductivity of aluminum, common heatsinks appear to be significantly oversized.

The "bottleneck" appears to be the heat transfer from the aluminum to the air, which is likely about 4000 times worse than the thermal conductivity within the aluminum itself.

Based on heat sink data, I estimate that approximately 0.0032 Watts of heat flow between 1 cm² of aluminum and still air with a temperature difference of 1 Kelvin.

My intake manifold has a surface area of approximately 1,300 cm², which would theoretically transfer about 4.4 watts of heat to the surrounding air if there were a 1K temperature difference.

For example, if there's a temperature difference of 40 Kelvin between the air in the pipe and the air in the engine compartment, the heat has to pass through two boundary layers: air-aluminum. This, in my opinion, reduces the heat transfer to approximately 2.2 Watts per Kelvin. So, with a 40 Kelvin difference, this would result in roughly 88 Watts of energy flow from the engine compartment to the pipe – assuming the air is stationary.

To, for example, heat the approximately 85 grams of air per second drawn in by the AZS at 2000 rpm and full load by 1°C or 1 K, my research indicates that approximately 86 watts are required, which is the same amount of heat that the pipe would transfer with a 40 K difference and air flowing on both sides.
A model that doesn't work in practice because the air being drawn in flows, rather than remaining static.

And now comes the biggest unknown for me: how does the transmitted power change when there is moving air?
Most likely, she will grow taller - but by how much .

Who can help?

Well then, don't even think about buying new cars.

They touted a 'compact cooling module' as a special feat of engineering.

Okay, so, climate control, liquid cooling, and water coolers, all as a single unit...

First, the climate cooler dissipates its heat to the liquid cooling system in the summer. And then, all that 'gunk' goes to the water cooler.

or, in traffic jams, the climate control and water cooler cheerfully blast air onto the LLK (likely referring to the driver or passengers).

falsified by fractions of a millisecond.

CU Gremlin.

christians wrote:

It is questionable, however, how much heat can be transferred through the relatively small surface area of a heat exchanger tube, which would be internally corrugated, to a relatively large volumetric flow rate.

Of course, this thing is not designed as a heat exchanger (with fins).

I'll expand on it and run some simulation measurements (results to follow).

With an engine oil temperature of up to 66°C, and after only a few seconds of full throttle to 4000 rpm, with an outside temperature of approximately 11°C, the oil cooler (LLK) probably isn't very effective (the path for outside air is clear, and the LLK is clean). In the summer, with prolonged maximum power output, I would consider 75-80°C to be quite possible.
If I could reduce the temperature of the intake manifold by a few degrees through insulation, that would already be a small gain – not necessarily in terms of power, but for the thermal relief of the engine.

gremlin wrote:

First, there's the climate cooler, which releases its heat to the LLK (Low-Level Cooling) system in the summer. And then all that grime goes to the water cooler... or, in traffic jams, the climate control and water cooler cheerfully radiate heat onto the LLK (liquid cooling system)...

Perhaps the intention is to make people aware of the cost of climate action.
It would only be noticeably felt if the airflow through the climate-controlled intercooler drops to the point where the soot reduction system, for example, operates 10% below its nominal speed .

Then, overall, Klima points out three key factors: the need for drive power, the charge air temperature, and the excess weight that needs to be hauled.

Considering only the specific thermal conductivity of aluminum, common heatsinks appear to be significantly oversized.

The 'bottleneck' seems to be the heat transfer from aluminum to air, which is likely approximately 4000 times worse than the thermal conductivity within the aluminum itself.

The transition from the heatsink to the air is even worse with copper than with aluminum. However, copper conducts heat better internally than aluminum, which is why, initially, heatsinks had a copper core and were then made of aluminum as the cooling material. All-copper heatsinks were only the really expensive ones. Aluminum is simply not up to the task of handling the heat generated by today's processors.

Best regards, WarLord.

WarLord wrote:

The transition from the heatsink to the air is even worse with copper than it is with aluminum. . .

Do you have any specific values for that, perhaps even including different flow rates?

Look at the diagram, which is located quite far down.

http://www.sigem-elektronik.de/elektro/glossar.htm#W{MARKER}

leolotus wrote:

look at the diagram, which is quite far down. [url][/url] Thank you

:Dhttp://www.sigem-elektronik.de/elektro/glossar.htm#W{MARKER}{MARKER}

ulf wrote:

leolotus wrote: Look at the diagram, which is quite far down. [url][/url] Thank you EDIT: I've done some more calculations with these values. Assuming that the airflow inside the pipe and around the pipe (i.e., in the engine compartment) is faster than approximately 20 km/h, the transported power will increase by a factor of roughly five compared to airflow at standstill (86 Watts, see above). With a temperature difference of 40°C between the intake air and the engine compartment, I would have a heat flow of approximately 430 watts. The ASZ (presumably a vacuum system) draws in approximately 950 mg per stroke at its maximum vacuum level. With 133 strokes per second, this results in a mass flow rate of 127 grams per second. With a specific heat capacity of 1.01 J/(g * K), the 127 grams of air will be heated by approximately 3.1°C. At 2000 rpm and with a halved mass airflow, the intake air temperature increases by approximately 6°C.

http://www.sigem-elektronik.de/elektro/glossar.htm#W{MARKER}{MARKER}

I can't shake the feeling that your Polo isn't performing as well as you hoped it would .


CU Gremlin.

I can't help but get the impression that your Polo isn't performing as well as you thought it would .


I have a suspicion that the 1/4-mile time to Ulf's bakery was not achieved in a new record time compared to the Golf 3... [img][/img]

Have I already mentioned that a 5-speed gearbox weighs approximately 8kg less than the 6-speed manual? :lol:http://www.cheesebuerger.de/smilies/schilder/108.gif{MARKER}