Mailing List flyrotary@lancaironline.net Message #10375
From: DaveLeonard <daveleonard@cox.net>
Subject: RE: [FlyRotary] Re: DeltaT Coolant was : [FlyRotary] Re: coolant temps
Date: Fri, 13 Aug 2004 05:45:08 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Mark, Ed took care of that right in the second line "So with Tracy's 30 gpm flow of water = 240 lbs/min"
 
Dave Leonard
Ed,
Please humor me (a non-engineer) while I ask a dumb question.  If it takes 1BTU to raise 1lb of water 1 degree, and you factor in 30 gpm flow to come up with a 2400 BTU requirement for a 10 degree rise for 1 lb of water, where does the number of pounds of water figure into the equation, or do we just ignore that issue?  Water is 8.34 lbs/gal, and say you have 2 gallons of coolant, that would be 16.68 lbs.  Seems that we would need to multiply the 2400 figure by 16.68 to arrive at a total system requirement of 40,032 BTU/min.  What am I missing here?

Mark S.


     At 09:58 PM 8/12/2004 -0400, you wrote:
Right you are, Dave
 
Below  is one semi-official definition of BTU in English units.  1 BTU is amount of heat to raise 1 lb of water 1 degree Fahrenheit.  
 
So with Tracy's 30 gpm flow of water = 240 lbs/min.  Since its temperature is raised 10 degree F we have
 
BTU = 240 * 10 * 1 = 2400 BTU/min
 
I know I'm ancient and  I should move into the new metric world, but at least I didn't do it in Stones and Furlongs {:>)
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