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Re: [Amps] LK 500 ZA heat

To: <>
Subject: Re: [Amps] LK 500 ZA heat
From: "Tom Osborne" <>
Date: Mon, 13 Aug 2007 19:20:11 -0700
List-post: <>
What was the original question?

> Carl OM,
> Tom is spot on.  This is a real answer just like Toms.
> OK so you insist on the heat exchanger analogy with your automobile and
> electric fan.  The reason that an electric fan is not sitting out in
> front of your radiator is because at 30+ mph the electric fan and its
> motor would get in the way and restrict air flow.  The fan is not
> running at this speed and the air flow through the radiator due to
> vehicle motion far surpasses what a fan could produce.   At low speeds
> and idle, the fan comes on and sucks air through the radiator.  A little
> is better than none.  Vehicles boil over during traffic jams don't
> they?  The ideal situation would be to move the fan in front of the
> radiator to run at idle and to remove the fan altogether at normal
> travel speeds.
> So an enclosed pressurized box of electronics is more efficiently cooled
> with a fan on the air intake.  Cooling is more efficient  if the air
> flow is turbulent versus laminar.  It is easier to direct turbulent air
> at tube pins and plate caps when these tube parts are close to the
> intake fan that is directing cool air at them.  OK, so you notice that a
> fan in your computer is in the power supply and in the exhaust path.  It
> is there because it is the cheapest place, not because it works best.
> The fan on your CPU blows onto the CPU and the fan on your video card
> blows onto the video chip.
> BTW, the reason your fan is electric is because most engines are
> transverse mounted in front wheel drive vehicles and because it is 
> cheaper.
> 73, Tim, W2UI
> jeremy-ca wrote:
>> Tom, you are so predictable. When you cant come up with a real answer you
>> resort to personal attacks.
>> I dont know when the last time you lifted the hood in a car but 
>> horsepower
>> robbing engine driven fans have been out of favor for around 25 years. 
>> The
>> choice of all manufacturers is an electric pulling fan. This also holds 
>> for
>> 500-800 hp and higher street rods with big V8's stuffed in very 
>> restrictive
>> spaces. The Internet is full of studies of the comparisons between push 
>> and
>> pull cooling.
>> The air flow analogy is valid no matter the platform.
>> Carl
>> KM1H
>> ----- Original Message ----- 
>> From: "Tom Rauch" <>
>> To: "jeremy-ca" <>; "dave arruzza" <>;
>> <>
>> Sent: Monday, August 13, 2007 3:28 PM
>> Subject: Re: [Amps] LK 500 ZA heat
>>>>> If you pressurize the inlet of a fan or blower, it greatly
>>>>> increases outlet pressure. If you draw on the outlet it
>>>>> hardly changes airflow. The inlet fan largely sets the
>>>>> volume of air. The same is true for restrictions. If you
>>>>> restrict an inlet, there is a huge air volume change. If you
>>>> Tell that to the millions of car owners with electric fans that pull 
>>>> the
>>>> air thru the restrictive radiator. Tests have long proven that trying 
>>>> to
>>>> push the air thru the radiator is a bad idea.
>>> Carl,
>>> It's just silly to drag in unrelated arguments against something that is 
>>> a
>>> clearly known fact, especially something so easy to prove with minimal
>>> research or experimentation.
>>> Cars suck air through the radiator because that's where the drive system
>>> is. They aren't about to extend a shaft through the middle of the
>>> radiator, so they burn up some extra horsepower with a less efficienct 
>>> air
>>> system. Also the movement of the car through the air is what does 90% of
>>> the air movement, the only real thing the fan does is cool the system 
>>> when
>>> the vehicle is stopped or at slow speed. That's also when BTU's 
>>> generated
>>> by the engine is less, since the fuel volume being burned is lowest.
>>> Analogies to a 200 horsepower engine in a system that is not pressure or
>>> noise critical and can't put the fan in the optimum place is a 
>>> tremendious
>>> waste of time.
>>>> Placing a small fan in exhaust mode has also saved many sweep tube rigs
>>>> from premature tube failure. Ask anyone who used Drake C Line in 
>>>> contests
>>>> for example.
>>> Anything is better than nothing Carl. He was talking about adding a fan 
>>> to
>>> a system that already has a fan, not a convection system like the Drake.
>>> This was just another lame meaningless analogy.
>>> It is an undisputable fact air movers act like I outlined, and something
>>> everyone designing or modifying a cooling system should know. Even 
>>> someone
>>> working on a car.
>>> 73 Tom
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