Newbie looking for advice on fuel cooling

Hiya all,

I was directed here by a friend of mine who I'd been speaking to about an on-board fuel cooler in my sprint/hillclimb saloon car. He suggested I put forward my thoughts on here and see what you technical guys n gals throw into the pot. Sorry to have my first thread as an enquiry, but races to be won this year and I'm keen to get something built soon!

I have an issue with the fuel system on my car collecting an enormous amount of heat from various sources (exhaust and engine) which means whilst it's running, the fuel can reach temps of 35c easily which is affecting power quite dramatically! I've insulated what I can to slow the heat absorbtion but now want to build an on-board cooling system capable of feeding the engine with petrol at around 0 degrees c. This has shown an extra 60hp on the dyno.

Here's a few ideas that have been put to me so far:

1) coil 10mm copper pipe inside a sealed aluminium tube full of water, freeze the water before each outing and pass the fuel through the copper pipe to the engine as the ice melts.

2) fit a small pump to a 10 row oil cooler, submerse the cooler into iced water and pump the fuel through this from the base of the tank back to the top of the tank. This could be kept inside the car and run as the car is driven.

3) fit a copper coil into the tank and pass liquid nitrogen through to cool the fuel in advance of arriving at the start line.

The quantity of fuel I'm talking about would be around 5 litres at a time and the base of the tank has a cylinder below to act as a swirl pot. There's spare fittings on the swirl pot (3 litre capacity) to allow me to try option 2 above. I already carry a large quantity of ice in an insulated container to keep the beer cold for the weekend so I have a source of ice at hand.

Would it be possible to build a 12v system capable of cooling this amount of fuel in around 10 minutes yet have it small and light?
Ideally I'd like to be able to chill the fuel to around -5c at the tank so it reaches the engine at around 0c.

Am I asking the impossible?

A few more points: The car is used for Sprints & hillclimbs and is therefore only ever driven hard for a maximum time of 30 - 120 seconds. This is why I can get away with carrying only 4 litres of fuel.

The car has a tunnel underfloor with an air gap between the bodyshell and the tunnel which the exhaust passes through (almost all the car length), this is where the bulk of the heat is picked up by the fuel.

The factory aircon has been previously removed for weight saving!

Any input would be greatly appreciated.

Many thanks in advance

Thermoelectric cooling would seem ideal for this application, continuously cooling just enough fuel to run the vehicle, as it travels through the fuel line.

Any form of icebank or liquid nitrogen would of course work but would be "labour intensive", messy and rely on human intervention.

My suggestion would be to reinstate and modify the A/C system...

But then again, I love tinkering.

The fuel tank is one of those aluminum race tanks & you have it in the boot ?

You refil the tank with just enough fuel for each run up the hill ?

Can you insulate the fuel tank & fill it with precooled fuel ?
then
during warm up & que for start line the precooled fuel will be through to the engine so full power for the start line.

Using pre cooled fuel would not add any weight to the car except for the tank & fuel line insulation.
Any onboard cooling system is going to add kg's to the car.

Suggest
1/ make new fuel line route as far away from the exhaust as possible & insulate but I am sure you have done that already.
2/ Insulate the tank.
3/ Try the ice method for pre cooling the fuel before filling the car fuel tank
4/ See if this works

If it does then you can investigate making a permanant trailer mounted fuel cooler rig.

Quote:

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Originally Posted by Thermatech

The fuel tank is one of those aluminum race tanks & you have it in the boot ?

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Yes the fuel tank is an aluminium box in the boot (60l) but the swirl pot hangs below. Unfortunately this is in direct airflow of all the hot air blowing through the tunnel. I have heat shields and insulation and they have helped a bit.

Quote:

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Originally Posted by Thermatech

You refil the tank with just enough fuel for each run up the hill ?

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I tend to have around 4-5 litres before the run, most of it in the swirl pot to stop surge.

Quote:

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Originally Posted by Thermatech

Can you insulate the fuel tank & fill it with precooled fuel ?

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I've been doing this at every event this year although it's becoming a real hassle! It stays cool for a short time but if there's a delay on the start line then the fuel heats up again by the time the light goes green.

Quote:

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Originally Posted by Thermatech

then
during warm up & que for start line the precooled fuel will be through to the engine so full power for the start line.

Using pre cooled fuel would not add any weight to the car except for the tank & fuel line insulation.
Any onboard cooling system is going to add kg's to the car.

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One of the biggest problems is the fuel pumps at 4.5bar and flows constantly to the injector rail and back to the tank via a pressure regulator. The 4 litres of fuel would pass a full loop in under a minute at idle (not as much return at full throttle though), each time collecting heat on 2 journeys through most of the hot airspace. With the engine idling the heat builds up in the airspace under the floor heating up everything -especially if there's no airflow from the front when stationary. Sometimes we have to que for 10 minutes.

Quote:

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Originally Posted by Thermatech

Suggest
1/ make new fuel line route as far away from the exhaust as possible & insulate but I am sure you have done that already.
2/ Insulate the tank.
3/ Try the ice method for pre cooling the fuel before filling the car fuel tank
4/ See if this works

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1/ pipes are insulated as best I can

2/Tank was insulated but am looking into forming an expanded foam insulation layer everywhere that is in the hot airflow.
3/I would use a chilled top up before the run which is best when the tank is empty but it's difficult to drain all the fuel from the tank between runs!
4/ I have the theory of cold fuel giving me the extra power, just need to keep it cool through the paddock, queing and during the run itself.

Because the engine is so highly stressed (610hp turbo 2.3L), i also have to make sure the engine oil is fully up to temp before the launch. This could mean 20 mins of idling if starting from cold, all the time keeping heat in the exhaust and adding heat to the surrounding metal which stores it for a while and adds to the problem.

I used to have the exhaust straight from the turbo exiting out the corner of the front bumper which took 90% of the heat away from the fuel system - but the rulemakers wouldn't allow it and the current configuration of exhaust is the best i can do.

Some thoughts....

1. Yes, pre-cooling the fuel seems the best option.

2. You could build/have built a cooling unit using a 12volt compressor. This could be powered through you support vehicle.

3. My van, Peugeot Expert has a fuel cooler fitted underneath for cooling the hot return fuel from the engine. This is like a small oil cooler and has an air scoop over it. Something like this could be added to the race car to assist perhaps.

4. Run the car on nitro and don't tell the others. :D

Quote:

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Originally Posted by Brian_UK

Some thoughts....

1. Yes, pre-cooling the fuel seems the best option.

2. You could build/have built a cooling unit using a 12volt compressor. This could be powered through you support vehicle

4. Run the car on nitro and don't tell the others. :D

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I'm tending to favour the small oil cooler and box (shoebox sized?) of iced water at the moment as it's compact, could be fitted inside the boot for access and I can run the pump in advance and when queing for the run. Would have to set the cooler up so cold water can freely flow through it.

The extra weight at say 5 - 7 Kg for that system would be nothing to add to the already 1200kg car (and the driver's a bit lardy too:o)

Sorry the rules say no nitro - which is a shame!

What about a dry ice box, fill it after starting engine, coil the fuel line in box Do not know what temp the fuel freezes at but dry ice is extremely cold,you will not need a lot of it, so a small box only.
magoo

as above

http://shop.ebay.co.uk/?_from=R40&_t...All-Categories

connect it up to your 12v battery and one side gets hot the other side gets cold... (you need to cool the hot side as it pulls heat away from the cold side)

sounds perfect to me ?

they normally have @60'C temp difference between the hot side and the cold side... (tho thats at a bit more than 12v for most iirc)

stack 2 up, one ontop of the other, then cool the hot side with your engine coolant... (because you'll have 2 stacked up, you can go to 120'C and still have 0'C at the cold side)

if you fix them between 2 CPU waterblocks it'll make it eacy for you to run the coolant/liquid to them :-)

(comething like this http://www.tekheads.co.uk/s/product?product=608576 - or you could make your own...)

madmac, have you thought about cooling the air in take as well. Apart from an inter-cooler after the turbo.
Venturis on air intakes can cool air before the turbo, as in freezing the air. They are / were common as aircraft cooling systems.
So with cold air and cold fuel, means larger fuel particles down the hole, bigger bang, more horsepower. One down sde of venturi cooling is the noise, but I don't think that would worry you.
magoo. [ old petrol head ]

A small 'cool supply' of liquid nitrogen, when flashed & used correctly, could probably be your answer.

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Originally Posted by Magoo

What about a dry ice box, fill it after starting engine, coil the fuel line in box Do not know what temp the fuel freezes at but dry ice is extremely cold,you will not need a lot of it, so a small box only.
magoo

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Good idea and I've considered this but it would be difficult to control would it not? if the pump was switched off it may freeze the fuel! I've been told the ideal temp of the fuel at the injectors should be around 0c.

Also difficult to get and store dry ice for a whole weekend at a campsite!

Quote:

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Originally Posted by Magoo

madmac, have you thought about cooling the air in take as well. Apart from an inter-cooler after the turbo.
Venturis on air intakes can cool air before the turbo, as in freezing the air. They are / were common as aircraft cooling systems.
So with cold air and cold fuel, means larger fuel particles down the hole, bigger bang, more horsepower. One down sde of venturi cooling is the noise, but I don't think that would worry you.
magoo. [ old petrol head ]

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Not looked into this in any depth but I guess it's something to consider too. The air temp from the turbo at 2.5bar is 212c and the Intercooler takes this down to 27c for the engine inlet so temps aren't too bad at the moment. This was measured on the dyno last year after we fitted the new Intercooler.

DesA: Liquid Nitrogen would certainly cool the fuel quickly but how would I build something to pass the fuel through and still have control of it from inside the car?

Gary: Thermoelectric cooling does seem ideal for this. Might be tricky to build a module to allow all the cooling effect to reach the fuel though? Would I not need a fairly large amount of these blocks to take all the heat away in a short time frame?

Sorry, I have little knowledge of thermodynamics which is why I was looking for input from those who do have knowledge! Some great ideas though, keep them coming!

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DesA: Liquid Nitrogen would certainly cool the fuel quickly but how would I build something to pass the fuel through and still have control of it from inside the car?

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Won't be overly difficult, if you put your mind to it. There'd be different ways to manage that.

Hire me & I'll design you a system. Heat-transfer is my stock-in-trade. :)

Hi guys
Magoo has a good idea - my cousin used to race and we noticed on a very cold morning the engine produced much more HP, I thought it was due to sucking in more dense air and the way his car was tuned. Does your swirl pot work well? Ive seen something like it for refrigerant liquid a few years ago.

Madmac.
I don't think you will have a problem with freezing the fuel. I worked in Siberia in winter, and the average night time temp was -35 'C We had a couple of those Lada 4x4 's never a problem starting or frozen fuel, Diesels always a problem.
Dry Ice comes in pellet s from BOC gases and keep them in a chillybin, will last for days.
magoo

Madmac.
With Formula 3 in the UK, all cars have the same air-take arrangement. The thing looks like a torpedo, and all have the same in-take hole/ orifice. They will act like a venturi. Do you know anyone running a F3 team, with the telemitry the have they will know exactly the air in-take and air to engine temps. Just another thought.
magoo

Quote:

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Originally Posted by madmac

Thermoelectric cooling does seem ideal for this. Might be tricky to build a module to allow all the cooling effect to reach the fuel though? Would I not need a fairly large amount of these blocks to take all the heat away in a short time frame?

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there's a lot to chose from, a 500watt one will pull 500watts of heat out of the fuel every second (as long as you set it up right)

how much fuel do you use and how fast ?

500w will drop the temp of a litre of water by 1'C every 2 seconds ? (I guess petrol will be about the same)

so your incomming fuel temp is 35'C

i element will drop the temp of a litre down to 0'C in approx 70sec - so thats about a litre of petrol a minut ?
2 will do it in 35sec - or 2 litres a minut ?

it would be easy to cool the fuel with them if you look at the CPU blocks I linked to above, while the ones linked arn't perfect... they give you a good idea of what you need.

the big advantage of these is that you can stack them up 2 high, and then cool the hot side with water right out of the engine radiator (from the bottom pipe of the radiator)

2nd big advantage is....they're not going use up any of your engine power as with AC systems etc...

(they will put a bit more strain on your alternator, but thats easily overcome with a small switch to cut out the alternator while you;re doing the hill climb.... I think this is pretty standerd practice ?)

DesA, am running on a budget and have had to do some hefty repairs recently which has used a chunk of the season's funds.

Tesla, the idea with the swirl pot was to have the return fuel being cooled as it returned by swirling it around the outside of the pot. The tank was designed and built when the exhaust exited through the front bumper and therefore was cooler outside than the returning fuel. Now that the exhaust runs through the floor, everything has changed and the heat is now an issue.

Magoo, From what I've heard, the fuel atomises differently if it's too cold and from advice of an experienced engine builder, the ideal temp would be around 0'c. The engine may lose power if the fuel temp goes too low.

The engine also consumes a collossal amount of air through a 4" intake and a venturi may restrict the flow enough to strangle the engine? Even if I could get the turbo intake down to 0'c, with the intercooler being air/air, the ambient temperature will affect the final intake temps so a venturi may only reduce intake temps by a few degrees overall. ie, if it's 20'c outside then there's no way the inlet temp can be less than 20'c.

Knighty, the fuel used would be around 2 litres depending on the track but this would circulate through the pump/fuel rail/tank many times. The pump is 440 litres per hour at 4 bar, the return fuel flow depends on how much throttle is used - more throttle = less return.

I've decided that any cooler I use will be completely seperate from the high pressure lines/pump the engine uses as I can't afford to have any restrictions that could cause a lean burn. A standalone pump and circulation system would be easy enough to hook up to the tank and would cool the fuel in the tank rather than as it's pumped to the engine. It's now a case of building something compact and light to cool the fuel as it circulates through the lines!

At the moment the car is undergoing a lot of work before this next event at the weekend so it's unlikely I'll have any cooling system up and running this week. I bent the front crossmember a few weeks back so am making a jig using my spare crossmember before it's fitted so in the future I can make a tubular one and save weight. Once the spare crossmember is fitted, I won't be able to make the jig so it needs dealt with this week.

There's a thread I have running on MLR showing the car and this season's successes here for any petrolheads. I can't post a link here yet but the thread can be found on lancerregister.com, thread number 249675

im definite for the theory of the miracle box,alloy plate moulded around stainless steel tube that doubles back on itself,works fantastic with beer a dose of salt over the top of the ice can freeze the plate given the conditions.dump the ice warm the plate so theres beer again.no different than running coiled pipe in a bucket covered in ice out the freezer,tell the oposition its for your coolling suit

I think we've settled on designing a thermoelectric cooler for long term use, but at the moment we're going to hook up a simple fuel/iced water cooler for the short term.

Thanks for all the advice - really appreciate the ideas and I will of course update when I have something up and running!

Donald

good luck fella enjoy

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Originally Posted by madmac

I think we've settled on designing a thermoelectric cooler for long term use, but at the moment we're going to hook up a simple fuel/iced water cooler for the short term.

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Yep... no reason a TEC can't be added later, up by the engine to compensate for heat gained in the tunnel.

Fit Like Donald!

Interesting replies about your fuel problem....heat?
what a pain....but without it, how could we keep things cauld!!!....liquid nitrogen must be the way i thinks.
The answer will come fan yer nae thinkin aboot it, so if you get a call at 2 in the morning and i'm screaming eureka!! im either drunk or found a way to get an extra 60 stallions!.........sorry to say, will be more than likely drunk...good luck tho!

Jas

hmmm twelve year chivas or lachanora chillin,a bit of liquid gold to go with that eureka

Update:

I tried a simple copper tube cooler with ice external to the tank and a small pump to flow the fuel through the copper tube. This worked fairly well but took 30 mins to cool the fuel from 28c down to 8c and used a huge amount of ice blocks!

I had some help from someone in the know to do some basic calcs to see what size peltier device I'd need but the cost and power consumption were prohibitive. Because I only do full throttle for under a minute I've decided I'd be best to cool the fuel externally and just pour it into the tank

Using a quick coulping and the pump already fitted, i can drain the tank safely in the paddock and add the pre-chilled fuel just before I leave the paddock for my run.

Interestingly, when I poured the cold fuel into the tank (at 2c) i see the temp by the time I get to the start line is 12-13c, so what i now need to consider is chilling the fuel to -figures before i pour it in the tank. Perhaps a small 12V freezer or as mentioned earlier nitrogen or CO2 chiller external to the car and big enough to take a 10 or 20L jerrycan.

One thing for sure, the car is definately quicker with the colder fuel! Have set another 2 class records since trying it

Hi Jas:)

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Originally Posted by madmac

I had some help from someone in the know to do some basic calcs to see what size peltier device I'd need but the cost and power consumption were prohibitive. Because I only do full throttle for under a minute I've decided I'd be best to cool the fuel externally and just pour it into the tank

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Did you consider the cost of combining these two strategies?... pour in cold fuel and then keep it cold with a pelt?

You would have a air compressor? 2 options 1st really cheap, run high pressure air through a drill, pass the exaust air through you stored fuel (then into the car), 2ed by a vortex cooler, use cold air to chill the store fuel

I race a vehicle as well and I am interested in thermoelectric cooling. My current project is similar to Donalds, yet slightly different. I purchased a Moroso Cool Can and will be installing it in the rear of my vehicle. I plan to put ice in it at the track. I will be running copper tubing from the cool can along the fuel rail all the way to the engine and back. Near the engine I will be installing a catch can that I will fill with antifreeze and water. The antifreeze and water mixture will circulate through the copper tubing via a small low pressure fuel pump. The fuel line from the rear to the engine will be insulated to reduce the heating impact.

This will cool my entire fuel line. I found a thermoelectric cooler that I'd like to apply to the outside of my metal catch can, but I know very little about them. Can someone please explain what else is needed to make this work for my application?

Many Thanks in Advance