REFLECTOR: 2 Pass cooler

[Laurence Coen]

Chuck,

It does make a difference.  Cool cooler first and hot cooler second is more efficient and is called a counter flow heat exchanger.  That's how the new gas furnaces for home heating achieve efficiencies in excess of 90%.

Larry Coen
N136LC


From: Chuck Jensen 
Sent: Friday, July 31, 2009 7:16 AM
To: Velocity Aircraft Owners and Builders list 
Subject: Re: REFLECTOR: 2 Pass cooler


Jim, not only that, but the oil in the second cooler will be, well, 'cooler', so there'll be less of a delta T, further reducing the effectiveness of the second cooler in series.  

Thermodynamic question.  If one is going to stack two coolers, is it better to put the incoming hot oil through the front cooler that has also has the coolest air, knowing that the second cooler will suffer from cooler oil and warmer air?  Or, is it better to put the second cooler that the oil passes through in front where it'll have the cooler incoming air.  The second cooler in line will see warmer air, but the oil is hotter, coming straight from the engine......or, does it make any difference?
Chuck Jensen 



  -----Original Message-----
  From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On Behalf Of Jim Agnew
  Sent: Friday, July 31, 2009 7:53 AM
  To: Velocity Aircraft Owners and Builders list
  Subject: Re: REFLECTOR: 2 Pass cooler


  The standard Velocity oil cooler at cruise will give about a 15 degree drop.  This is based on a friends comments after many years of race car building and racing with similar coolers.  I would like to know if these are stacked coolers is the 20% drop from the first to last cooler or overall.  If there stacked then the second cooler is working with much warmer incoming air.

  Jim
   
  James F. Agnew

  Jim_Agnew_2 at Yahoo.Com

  Tampa, FL

  Velocity 173 Elite Aircraft Completed & Flying






------------------------------------------------------------------------------
  From: "aminetech at bluefrog.com" <aminetech at bluefrog.com>
  To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
  Sent: Friday, July 31, 2009 2:49:20 AM
  Subject: Re: REFLECTOR: 2 Pass cooler

  Stewart Warner

  --- scott at tnstaafl.net wrote:

  From: Scott Derrick <scott at tnstaafl.net>
  To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
  Subject: Re: REFLECTOR: 2 Pass cooler
  Date: Thu, 30 Jul 2009 20:10:30 -0600

  is this the Aero-Classic cooler?  Stewart Warner?

  John Dibble wrote:
  > Yes.  I'm trying to get a feel for what a 20% increase in cooling means.  The vendor claims
  > a 15-20 F reduction.  Anyone have temperature data on oil in versus oil out of the cooler?
  >
  > John
  >
  > Scott Derrick wrote:
  >
  >  
  >> So some plumbing changes needed to replace the original....
  >>
  >> John Dibble wrote:
  >>    
  >>> Scott,
  >>> I lost your post, but the answer to your question is all dimensions including the bolt
  >>> holes are identical.  The only difference is that one oil line connection is on the
  >>> bottom and the other on top, same side.
  >>>
  >>> John
  >>>
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