View Full Version : help needed selecting components for aircon to chill fuel

02-04-2017, 03:54 AM
I've come here to get some help for an a/c system Im designing for my project truck, a single cab off road exploration/camping vehicle (A '89 Unimog). The operating environment it will be exposed to is extreme; ambient temperature frequently +45 degrees C and high humidity. Aswell as the heat, it will be exposed to dust and vibration, so it will need to be a rugged system. So basical its function will be the same as any vehicle a/c system with one difference. I want to use the refrigerant to chill the diesel fuel as much as possible before it enters the engine. To do this i will build a tube/shell heat exchanger unit, with the diesel flowing through the tubes and the cold refrigerant passing through the shell. Attached is a link regarding the heat exchanger design concept.

This is an experiment to see if it will lower exhaust temps and therefore allow for more boost and fuel, resulting in more power :)
So i need to design a cooling system that will chill the fuel and also cool the cab (single cab).
Now i don't have a very extensive grasp on all things a/c, all i can figure is I want to fit the biggest remote condenser unit i can. So far i think i will go with this 39000 BTU RedDot condenser


And as for the compressor, a guy who has an a/c retrofit kit for the truck, uses the a Unicla 200 Series compressors.

What i need to know is, would the size of this compressor suit the capacity of the condenser, or do i need to go bigger?
And what gas should i use? From what I've seen, here in Australia, there is R134a or R404a, is there a better option.

Thanks for your help!

02-04-2017, 04:23 AM
Hi Man,


Here my 2cents..

AC for Cab - Great! I'd suggest searching for a "Package" or "kit" I'm sure you know how to google.

Chilling diesel line - ok, I grasp the concept, but I wouldn't bother. Sure, I own a 4wd, I've been off-road but I just wouldn't bother.

For every litre of diesel you squirt into the engine, about 1000000 cubic decilitres of air is used for combustion - one litre of supercool diesel is going to drop that exhaust temperature by exactly five eights of a nano celcius.

Ever heard of something called "cost versus benefit"? How much is this supercooler going to cost?? 2k? 5k? How much spiced rum can you buy same - pretty sure I could forgo cold deisel for spiced rum.

Aaand, to me, it just one more thing to crap out on the side of the road..

Happy tinkering