Landracing Forum
Tech Information => Technical Discussion => Topic started by: SteveM on September 29, 2016, 04:18:25 PM
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I seem to remember seeing a thread a while back about how much cooling capacity was needed to run an engine using a "reservoir" style cooling system as opposed to a radiator style heat exchanger. I can't find the thread now.
Since I can't find any previous discussion, how about starting a new one....
Let's say I have a 300 HP engine and want to use a non-pressurized cooling system with "X" gallons of water in circulation, is there a rule of thumb to solve for "X" when designing a system?
Steve.
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Ooops - nevermind, I found the original threads....
Steve.
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Post the link for the original :-D
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What Frankie said....
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http://www.landracing.com/forum/index.php/topic,13886.0.html
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http://www.landracing.com/forum/index.php/topic,14302.0.html
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Thanks Steve. I have one of those non radiator type cooling systems in the race car. Wanted to see if I was close in capaactiy
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Mike,
You should really reconsider using a non pressurized system, especially with a turbo motor. The increased water pressure helps prevent the water from boiling especially around the exhaust port, which can be critical in a turbo engine, especially with 16+:1 compression ratio!
Rex
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I think I remember, (CRS) that the big Cummins water pumps run 40 to 45 psi normally at road rpm.
Ron
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SteveM- thanks for posting those links. I must have neglected to read that discussion the first time around- good info.
I don't know that I'll ever need to answer this question, but anyway- is tap water (at ambient temperature, for replacing hot water in tank) available on the salt? At El Mirage?
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Jack... of course water is available.... all you have to do is bring it. :wink:
We've been doing that for about 38 years... :cheers:
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Lots of thermal transfer thoughts swirling through my head right now.
I'm looking into tube-and-shell type heat exchangers for my applications.
The industry in which I'm employed may be able to provide a source of cheap-ish, used industrial tube and shell units that would be pretty easy to package in a race vehicle, and not require much fabrication.
Steve.
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Steve,
I switched to a heat exchanger type setup last year and an ice tank after reading through the posts you referenced earlier. What I ended up doing was having a custom aluminum radiator made that the core is enclosed to have water flowing across rather than air. The radiator core size is only 15" wide x 5.5" tall x 2.75" thick. I have an ice water tank which will hold about 9 gallons of all water (or about 40lbs of ice + water) and has it's own electric pump to circulate across the radiator core. I have this circulating pump set up that I can manually turn it on or it can be automatically turned on by a trigger point from the engine water temperature gauge, serving as an electronic thermostat.
I'm running Flathead Ford which is not at the 300hp your talking of, but it dumps a lot more heat into the cooling system compared to that new fancy overhead valve stuff, so probably a decent comparison. This year at Bonneville with the engine starting temp around 110-120 the ice tank would begin to circulate right around the 2 mile and maintain whatever set point temp I had it at (usually 180-190). Once on the return road and turning all the pumps on it would cool the engine down to about 140. The really nice thing was we could take out some warm water from the ice tank, put in a bag or two of ice, run the pumps and it would be right back at 100 degrees and ready to run again. I am really satisfied with the setup I ended up with, which will have enough cooling capacity to an eventual goal to be able to run the long coarse, if I can make enough horsepower.
When I was considering the change to this system I also looked at heat exchangers and I stayed away from them mostly because of space constraints. However if you do go that route pay attention to their BTU transfer rate at different fluid temps. A lot of these are intended for much higher temperature differentials than you will be dealing with and can be misleading when looking at the numbers.
In the pic below the tank at the back of the engine is the "radiator/heat exchanger", the one with the cap off is the ice tank. The engine runs fully pressurized and the ice tank is vented and the water could boil off if need be. I agree with Rex and would avoid a fully unpressurized system for the localized boiling.
(https://c7.staticflickr.com/6/5813/22307114806_58877e8bb8_z.jpg) (https://flic.kr/p/zZcN4G)Untitled (https://flic.kr/p/zZcN4G) by Andrew Welker (https://www.flickr.com/photos/vonwelker/), on Flickr
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Steve,
If you are considering using a water to water heat exchanger then go with the new(er) brazed plate style which is much more efficient than a shell and tube and much smaller. Check this site out and you can see what I am talking about. http://www.brazetek.com/brazed-plate-heat-exchangers (Also much more efficient than a "radiator in a tank" application and much smaller and probably less expensive.
Rex
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WOW - lots of good ideas flowing here. AWelker - the setup you have developed on your lakester looks like it's as well thought out and executed as anyone could ask for. That is a super-tidy package!
Rex: thank you for the link on the brazed plate heat exchangers. They definitely look more compact than a tube and shell exchanger of similar capacity. At my day job, we use a mix of plate-and-frame and tube-and-shell exchangers for different applications. The link you provided is the first place where I've seen appropriately sized plate-type heat exchangers. As of right now, this looks like the most practical solution for future development. I need to dig a little deeper - I didn't immediately see any BTU/Hr ratings on those brazed units.
Since my vehicle is still a truck, the good news is that it has a bed which can be used to haul stuff like water, tanks, pumps, etc. I will definitely be digging deeper into this topic!
Steve.
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The engine cooling loop definitely needs to be pressurized. I'm wondering if the engine loop will benefit from a small-ish reservoir (maybe a couple of gallons) as opposed to plumbing directly from the engine to the heat exchanger.
On the cooling loop side, I have room for a big tank.
Steve.
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BE sure and use Distilled water---do not leave water in your cooling systems because of electrolysis ---I run zincs also ---less noble metals and all
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Steve,
What you're thinking with a small reservoir is pretty much what I have. My radiator/heat exchanger will hold about 1-1.5 gallons on the engine side and is the highest point of the system. On my old cooling system I just had a 6lb aluminum propane tank converted as a pressurized reservoir, also held just under 1.5 gallons and at the highest point. Both worked well to keep the engine full with a little reserve.
This was the old setup with a small upper tank:
(https://c5.staticflickr.com/2/1511/25924388524_62dd663c30_h.jpg) (https://flic.kr/p/FuRgvW)IMG_0131 (https://flic.kr/p/FuRgvW) by Andrew Welker (https://www.flickr.com/photos/vonwelker/), on Flickr
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Steve,
You might also consider using the 77-83 BMW three way thermostat which circulates the engine water through the engine until its rated temp is reached and then it opens and modulates the cool water from the cooling system through the engine. You can find them on E Bay for around $15.
Andrew,
I love the detail on your lakester! BUT (you knew there had to be one!) you should really consider using flared inlets on your injector tubes. The potential air flow increase can be as high as 15% and it is free. I have a great article by Dr. Gordon Blair (British air flow expert) if you would like me to send them to you.
Rex
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The plate heat exchanger in our heating system is about 12" x 6" thick and maybe 8" high. I can't find ratings on it -- but it manages to heat the house and the hot tub - total maybe 100k BTU/hr - without a high duty cycle. How many BTU/hr from an engine?
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1 hp = 2,544 but/hr so the numbers get big quick when you talk per hour
Rex, thanks and you got me. That pic was from 2012 when I ran out of time. If you look close on the earlier pic I posted there are clamp on billet aluminum inlets that I probably put too much time into. Not sure about the paper you are talking about but I read something with inlet shapes versus drag coefficients. Nice catch.
Andy
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Andrew, you have a stunningly beautiful tank. A real work of art. I almost hate to see salt on it.
John
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Mike,
You should really reconsider using a non pressurized system, especially with a turbo motor. The increased water pressure helps prevent the water from boiling especially around the exhaust port, which can be critical in a turbo engine, especially with 16+:1 compression ratio!
Rex
Even though the "heat out" side of the cooling system may not be pressurized, the block/head itself will be pressurized by the water pump (presuming a real mechanical pump and not some dinky electric aquarium pump). I have logs showing a steady 20psi of coolant pressure in the block with a totally unpressurized tank. This is another turbo Toyota six capable of four digit power and the "unpressurized" cooling system has worked fine.
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Not to beat a dead horse but.
I understand about the pump pressure. But some engines could flow differently in the water jacket (flat heads) and cause hot spots. More pressure would raise the boiling temp.
My heads have steam ports above the exhaust valves so evidently steam pockets is a problem.
I guess my question is, if you have a 20 psi pressure system, wouldn't the block pressure before the thermostat then become 40 psi with the manual water pump and raise the boiling point that much more?
Ron
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Rex
How would the BMW thermostat be plumbed? It appears from the pictures that it opens straight through and bypasses to the side. Where or how would the bypass be hooked up?
Ron
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Rex
How would the BMW thermostat be plumbed? It appears from the pictures that it opens straight through and bypasses to the side. Where or how would the bypass be hooked up?
Ron
Assuming you are looking at an M10 thermostat.
- Water pump draws from the side port.
- Port with 45 tees anywhere between engine and the inlet side of the radiator.
- Port on the other end draws cool water from the radiator outlet.
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I definitely need to do some research so I can understand this BMW setup better....
I love learning new stuff! :-D
Steve.