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-   -   AC Aero (Higgs Diesel) E-330 Hawk Engine (https://vansairforce.net/community/showthread.php?t=167537)

BillL 02-15-2019 10:54 AM

Quote:

Originally Posted by majuro15 (Post 1324905)
Ross, do you have any pics or designs for a HX? I'm only finding some diesel truck stuff at this point before trying to roll my own as a test.

Ross has an excellent design for the air side, but you might want to provide information to the HX manufacturers (engineering sales dept) of thermal conductivity, specific heat, and viscosity to ensure the passages have adequate turbulence for your cooling fluid. You might not want to mention the actual fluid as they may not want to be involved. It might be called a "proprietary" fluid.

Mike S 02-15-2019 10:59 AM

When I hear about using the fuel as a heat sink, all I can think of is TWA 800.

Please be careful...............

majuro15 02-15-2019 11:04 AM

Mike, TWA went down because of fuel vapors exploding the center tank due to chafed wires arching. We won't have electrical inside any fuel tank! We also aren't looking at temperatures that will be close to boiling point or autoignition temperature.

We will follow your advice of being careful though!!!!

Mike S 02-15-2019 11:13 AM

Good, awareness was my goal.

Good luck with the project.

rv6ejguy 02-15-2019 11:19 AM

Quote:

Originally Posted by majuro15 (Post 1324905)

Ross, do you have any pics or designs for a HX? I'm only finding some diesel truck stuff at this point before trying to roll my own as a test.

King Airs pass the fuel through the oil coolers but I bet that's an expensive part.

These are popular on race car stuff: http://laminovapro.com/ http://laminovapro.com/laminova-oil-cooler-information/

rocketman1988 02-15-2019 11:21 AM

And
 
Many commercial aircraft use fuel to cool...things...

airguy 02-15-2019 11:33 AM

Quote:

Originally Posted by majuro15 (Post 1324905)
Then it becomes a question of how to decide where the fuel goes based on heat, wing first then up through the system then to HX first or to small HX then to wing, etc. What we are afraid of is getting to a low tank level and running out of options to get rid of the heat.

Highly recommend you take it direct to the air heat exchanger first - you get a much higher thermodynamic efficiency with greater delta T, which translates into a smaller exchanger, which translates into less cooling drag. Any heat left over can go the tank skins.

Toobuilder 02-15-2019 12:11 PM

One point seemingly overlooked here (and it might be me) is the fact that aircraft using fuel for cooling "stuff" are dealing with thousands of gallons and rely on huge thermal mass. There is very little "cooling" due to the airflow over the wings. The concept was explored quite a bit with wartime development and found unworkable for engine cooling. Seems to me that pumping a high thermal load into a small and rapidly diminishing quantity of fuel is a thermal runaway event in the making.

BillL 02-15-2019 01:18 PM

Quote:

Originally Posted by Toobuilder (Post 1324932)
One point seemingly overlooked here (and it might be me) is the fact that aircraft using fuel for cooling "stuff" are dealing with thousands of gallons and rely on huge thermal mass. There is very little "cooling" due to the airflow over the wings. The concept was explored quite a bit with wartime development and found unworkable for engine cooling. Seems to me that pumping a high thermal load into a small and rapidly diminishing quantity of fuel is a thermal runaway event in the making.

The injectors on the early Ford Powerstoke Diesels (the HEUI injectors) bypassed fuel back to the tank. Many factors, but it got so hot as to melt the poly tanks Ford was using. And the purpose was not to cool anything.

Jet A boils at 375F, EGW boils at 230-250F. Both depending on the pressure of course, BUT the numbers - specific heat of Jet-A is 43% of water, and thermal conductivity is 17% of water. Both of which will drive up operating temperatures for the cooling system. It is certainly possible too cool this way, and we wont engineer within this forum, but it is quite different and having AES involved for the whole system is a real advantage. They will have access to data that is hard to get otherwise.

DanH 02-15-2019 01:33 PM

The driving requirement seems to be a need for 130F fuel at injection delivery. The question is thus how to heat the fuel.

Having brainstormed a fuel-cooled system, sit down and map out system components with conventional coolant. Make a hard comparison.

Fuel heating could easily be done via a simple tubular passage through one of the tanks on the water-to-air exchanger, just as transmission and engine oil is temperature regulated in automobiles. Very conventional, relatively safe, with high acceptance.


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