Originally Posted by
waldig
PROLOGUE:
Results:
The stock ( series ) IC produced water temperature drops of 7.1, 5.0 and 3.9 degrees for a flow rate of 2, 3, and 3.9 ( 4.0) gallons per minute. I calculated the Btu rates, and got surprising results in that the 2 GPM provided 6336 BTU/ hour and 3.9GPH a greater water flow gave me 4956 BTU/ hour heat rejection rate. This all seemed wrong to me and was an issue to understand. How did better water flow reject LESS heat to the air stream - - - back in a moment.
My pet parallel flow IC seemed to operate correctly in that the heat rejected followed the water flow and did better with higher flows. When I crunched the numbers it worked out that the 2 GPM flow rejected 7104 BTU/ hour, 3GPM rejected 7200 BTU/ hour and at 4 GPM we were able to reject 7488 BTU/ hour a definite gain over the stock design. I will say that the parallel IC is a definite better design and will reject more heat and flow more water.
Will this wake the sleeping bear?
See image attached - I've included both USImperial and SI units
For those not willing to read the original post,
Waldig ran hot water through his IC whilst sucking air through the air side and measured the temperature drop of the water.
Good technique, but it needs to be caveated with the fact that the air was drawn through the IC at what would appear to be a much lower rate than what would be seen on a WOT event.
Based up on the heat the water losses, my guestimate indicates maybe 125cfm versus a WOT which is up around 500-800cfm (
depending on your setup).
Not sure what's going on, but I get different results to Woody (
all respects).
I think my calcs stand up but am willing to accept counter if there is any err.
The important conclusion I found was for the Series Format IC,
when the flow was doubled, the cooling effect increased by 9.8%.
It would be good to do 200-300 cfm or even 500....but we'll see.
---------------------------------------------
For those of us
in the minority.....
Lets get a little more techincal....the others can switch off.......yawn....
ZZZZZZZZZzzzzzz......
Increasing the flow of air or water, increases the reynolds number.
The water and air heat transfer coefficients are also directly related to their
Reynolds number.
That is - increasing the flow, increases the reynolds number which increaes the heat transfer coefficient.
However doubling the flow of water doesnt necessarily double the heat transfer coefficient as shown in the results. In the results, doubling the flow of water only allowed the air to pick up 10% in additional heat.
The same would apply to the air.
It will be interesting to see how this develops.......
Thanks - Waldig/Woody for generating the data - The Mopar and MB communities would be lesser without his brains and energy.