[Tigers] Tiger Cooling

[Smit, Theo]

That kind of thinking is pretty suspect, but in order to really compare the effectiveness of the radiator construction you have to look at all of the contributing factors:

-          The radiator core is not made of either pure aluminum or pure copper, and a little bit of alloying metal can have a large effect on the heat transfer coefficient.

-          The cores are THIN. Therefore, the heat transfer coefficient of the core is not as critical as the surface area of the tubes and whether or not the coolant flow through the tubes is laminar or turbulent; or whether or not the airflow between the tubes is laminar or turbulent.

-          Most brass radiators have the cores lined up in a row. The third or fourth row does not do much cooling. Most aluminum radiators have only two rows of fins, and they may be staggered so that each row has more exposure to the incoming airflow. Part of the reason that aluminum rads work better in many applications may simply be that they flow much more air.

-          Gotta look at long-term chemistry in the cooling system too. What happens to your coolant over time b does it coat the internals of your cooling system with a layer of gunk? If so, it may clog the core tubes; at least, the cooling system efficiency will be determined by the heat transfer coefficient of the gunk rather than the core tubes. I donbt know if aluminum is intrinsically better than brass there b but I will be careful to run distilled water/coolant mix as opposed to a tap water mix, so as to prevent issues with calcium deposits.
Theo


From: CoolVT at aol.com [mailto:CoolVT at aol.com]
Sent: March 21, 2012 10:58 AM
To: Smit, Theo; tigers at autox.team.net; dave at munroe.ca
Subject: Re: [Tigers] Tiger Cooling

Theo,
I agree with directing the flow through the radiator and blocking the proper areas. I have done everything that you've done in that area.
In regards to the type/material of the radiator.  I was at a show recently where a radiator supplier (all aluminum models) had about 100 rads on display. Most were ready  made for certain cars. I was impressed because the prices looked awfully good.  He said they could make up any configuration that someone would want. I asked how much more efficient aluminum would be over brass for the same size. He said about 25%.  I said that I thought the brass would be a better conductor or heat and therefore more efficient.  He said "no".  He said you put your hand on a brass radiator after a hard run with a car and you'll burn your hand.  Do the same with an aluminum and it will feel cool. This, in his mind, was saying that since the al. felt cooler that it was dissipating  heat better than the brass.  I came to the conclusion that he was probably not someone i would want designing a radiator for a Tiger.
Mark

In a message dated 3/21/2012 12:43:10 P.M. Eastern Daylight Time, Theo.Smit at dynastream.com writes:
Hi Mark,
I donbt think that there are any quick cooling aids for the Tiger b all of them require attention to detail to get more than just a marginal benefit.

The Cressida fan is about 12b diameter and has an integrated steel shroud; it just barely fits below the sheetmetal in the nose. I used foam adhesive tape to seal the gap between the rad matrix and the shroud. The problem you always have with pusher fans is that the motor obscures some of the available area; a second thing is that if the gaps arenbt filled, then the air can just go out the side rather than through the radiator. The reason why I used this fan is that it was evidently designed from the outset as a pusher application. A lot of aftermarket fans are designed as a puller, and then when theybre used in a pusher application they really donbt move anywhere near the air that theybre supposedly rated at.

The only thing that would be nice is to have a similar fan, but larger, so that it would move more air over more of the radiator. Youbd end up with part of the fan output deadheading against the lower radiator support though.

Moving air through half the rad should be more than sufficient, since the fan is only required to boost airflow at low speeds. You just have to make sure that the air youbre moving is really going through the rad rather than around it, and that itbs moving with sufficient speed.
A secondary issue is that if the fan only covers part of the radiator core, are those core tubes actually flowing enough coolant to do the job?

Theo

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