Quote:
Originally Posted by dustyfirewalker
i havent taken heat transfer systems yet, so im not exactly sure how to go about finding the right surface area to transfer the heat trough a particular substance.
im hoping someone could point me in the right direction, alot of what ive found is just "maximize surface area for best heat transfer" but i dont have a whole lot of room in my engine bay
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I'll take a stab at calculating heat transfer area. Some assumptions:
Exhaust gas temperature 1500 deg F.
Exiting heated mixture temperature 700 deg F.
Counterflow heat exchanger.
Heat transferred 113 Kw.
Heat transfer coefficient 5 BTU/hr-ft2-deg F
Estimate average temperature difference between hot and cold side is 700 deg F. Then the heat transfer rate per square foot is 5 BTU/hr-ft2-deg F X 700 deg F = 3500 BTU/hr-ft2.
The total heat transfer rate is 113 Kw X 3412 BTU per KwH = 386,000 BTUH.
Then the heat exchanger area needed is 386,000 BTU/hr / 3500 BTU/hr-ft2 = 110 ft2. This seems large. If the real heat transfer rate is larger, the required area will be smaller.
Another source of error is the average temperature difference. I just made a SWAG. If you feel ambitious, calculate the heat capacity of exhaust gases resulting from 500 ACFM into the carburetor, then calculate a more correct average temperature difference.