Landracing Forum
Tech Information => Technical Discussion => Topic started by: metermatch on May 09, 2014, 08:07:49 PM
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I have been contemplating a different cooling system for my CRX.
I like the radiator in tank idea, but it looks like a lot of work.
How about something like this?
http://www.altheatsupply.com/index.php/shop-by-needs/outdoor-wood-furnace-parts/plate-heat-exchangers.html
My car is about 225hp at the crank. I was thinking of using an about 15 gallon water tank.
I was thinking of a 100 plate model for about $400: Rated at about 250,000 btu/hr. Or about 4000 btu/minute. My quick calculation: My 225 hp motor sends about 75hp of heat to cooling system - so 75hp * 42 btu/min per hp means about 3200 btu/min my motor would send to the cooling system.
Smaller, ready to go compared to building something.
I was thinking of just warming up the engine to about 180-200 degrees to start run, thermostat beginning to open, water circulating through one side of the heat exchanger, and then when leaving the line, turning on an about 20 gpm pump to circulate the water from the 15 gallon tank through the heat exchanger, and then back into the tank. In the end, it would have the capability to absorb the energy needed to heat 15 gallons water from 100 degrees to perhaps 200 degrees. Of course I could increase heat absorbtion capacity by starting with more like 50 degree water.
Engine side of heat exchanger would be pressurized to 20-30 psi based on radiator cap, and water tank side would be open to atmosphere.
These heat exchangers I believe are used for solar heaters and for boilers for houses, meaning they can handle more than enough pressure for our application.
Will something like this exchange the heat fast enought?
Thanks,
Jeff
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I run radiator in water, but have been looking at this exact thing.
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That looks like a good idea. :cheers:
Maybe guys still use radiators due to the cost.
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A "total loss" cooling system has been used successfully by air racers for some time.
Regards, Neil Tucson, AZ
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Neil, would you care to elaborate for us simple folk?.
I'm just about to build my radiator box and one doesn't want to look back and say "Aw man, I shoulda done that!" :-D
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I guess a total loss system would be a bit better than my idea. If I start with say 15 gallons of cold water, pump it through the heat exchanger and then back to the same 15 gallon tank, it will pre-heat the remaining water and get progressively less efficient as the run progresses. Delta T will become less and less.
If the water from the heat exchanger is dumped overboard, it wouldn't be preheating the remaining cooling water.
Jeff
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Mike;
Here is a post from an air racing site regarding the cooling system for a highly modified P-51 Mustang named "Stilleto":
"Matt Jackson
02-28-2007, 09:17 PM
Stiletto was originally built after the Anson Johnson racer from the 40's. It had wing radiators and was the model for the original Stiletto design. This however was changed when Bruce Lockwood and the guys from the MOF removed the wing radiators and installed the total boil off system. Essentially they submerged the radiator in a tub and allowed the heat of the engine to be ejected through the process of boiling off as steam. The Germans had perfected this in the late 30's and it worked excellent. They essentially eliminating all air over the radiator and having no scoops with the exception of the carb inlet. The aircraft used less water boiling during a race then the current mustangs spay over the radiators now. In 1992 I think I used 60 gallons. It also had the same range cross country as a stock P51 as you would run out of fuel before running out of boiler water. The problem was having to fill with water at each fuel stop, just another step to go fly. This is still the ideal cooling method for a liquid cooled race plane however and would certainly provide great speed gains for the likes of Dago, Strega and any other race mustang for that matter. The issue however is money, time and desire. By the looks of the current situation in racing, it won't be long before the unlimiteds will be arriving from the Sport class. It will be like the 30's all over again."
I hope this brief explanation is OK.
Regards, Neil Tucson, AZ
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Total loss water/cooling systems are covered by rule 1.N, page 16.
DW
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Dan;
This type of cooling system should not do any damage to the course; the only thing sent overboard is water vapor-- steam. No liquid is dumped out.
Regards, Neil Tucson, AZ
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No different than the Brits running a steam engine.
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Or us blowing a head gasket every run. :-P
At least we didn't have to go to the truck stop for a hot showers. :-D
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I understand now. If you are not steaming at the end of qualifying you haven't made the top 10 at Daytona
DW
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Does anyone have a formula for amount of water needed in the tank vs horsepower? We are planning a system like this and will have up to 2500hp but most likely not more then 2000hp
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Does anyone have a formula for amount of water needed in the tank vs horsepower? We are planning a system like this and will have up to 2500hp but most likely not more then 2000hp
I made up a spread sheet for intercooler ice water...
http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html (http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html)
...but it considers the massive amount of BTU's that it takes to convert ice into water so probably won't help and I don't know how accurate it is even for that application. I should know more after we can run Hooley's Stude harder in August.
One thing with your projected HP is that you should be able to make the run faster and also you for sure won't be using the 2000 HP for the entire run.
Are you considering this turn the water to steam idea? I can see it working but with the limited runs we make and everything else that would need to be figured into such a system just can't see it as and easy solution. We have the ...
(http://purplesagetradingpost.com/sumner/Hooley%202013/rad-heat-shields-30.jpg)
http://purplesagetradingpost.com/sumner/Hooley%202013/13%20-%20construction%20menu.html (http://purplesagetradingpost.com/sumner/Hooley%202013/13%20-%20construction%20menu.html)
rad-in-a-box and a 30+ gallon tank and feel we are not going to have problems with up to 1500 HP and considering that the car would complete the run even faster potentially with more HP feel it is going to work into the future for us,
Sum
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Does anyone have a formula for amount of water needed in the tank vs horsepower? We are planning a system like this and will have up to 2500hp but most likely not more then 2000hp
I made up a spread sheet for intercooler ice water...
http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html (http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html)
...but it considers the massive amount of BTU's that it takes to convert ice into water so probably won't help and I don't know how accurate it is even for that application. I should know more after we can run Hooley's Stude harder in August.
One thing with your projected HP is that you should be able to make the run faster and also you for sure won't be using the 2000 HP for the entire run.
Are you considering this turn the water to steam idea? I can see it working but with the limited runs we make and everything else that would need to be figured into such a system just can't see it as and easy solution. We have the ...
(http://purplesagetradingpost.com/sumner/Hooley%202013/rad-heat-shields-30.jpg)
http://purplesagetradingpost.com/sumner/Hooley%202013/13%20-%20construction%20menu.html (http://purplesagetradingpost.com/sumner/Hooley%202013/13%20-%20construction%20menu.html)
rad-in-a-box and a 30+ gallon tank and feel we are not going to have problems with up to 1500 HP and considering that the car would complete the run even faster potentially with more HP feel it is going to work into the future for us,
Sum
All good info. Thanks. I was thinking of just the radiator in a box full of water and not a separate tank with a pump moving water across the radiator core. I like your setup though. I figured that if I do the math on the full power potential and more time then we will actually run in one pass at Bonneville, then the system will be overkill.
Another thing I didn't think about was how much more efficient the radiator becomes when turned into a water to water unit. We can run a smaller radiator for better packaging.
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.... Another thing I didn't think about was how much more efficient the radiator becomes when turned into a water to water unit. We can run a smaller radiator for better packaging....
We could of probably run a smaller radiator but this one wasn't that expensive and it is a 2 pass radiator which I also wanted to use. Another advantage with the water in a separate tank besides moving the water past the rad. is that you can preheat the motor and not preheat any of the cooling water except what is in the tank around the rad..
Another obvious advantage over just a cooling tank, no rad-in-a-box, is that now you can run pressure in the engine side and none in the cooling side. That sure helps with a lot of engines to help avoid steam pockets.
The driver turns the water pump on just before leaving the line, but the pump could also be activated by a switch on the shift linkage, say on the 1-2 shift. I'd like to add that just in case the driver forgets to turn the water on.
Of course that never happens :-o 8-) :oops: :oops: :cry: :cry:,
Sum
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Does anyone have a formula for amount of water needed in the tank vs horsepower? We are planning a system like this and will have up to 2500hp but most likely not more then 2000hp
It takes 1 BTU to heat water 1 degree F and then it takes 970 BTU more to convert it to steam. Water boils at 212F (not considering altitude) so if you raise 10 gallons of water (83.3 lbs (8.3 lbs/gal)) from 92F to 212F , it takes (212F - 92F) x 83.3 lbs = 9,996 BTU. Converting all of it to steam requires an additional 970 BTU/lb x 83.3 lb = 80,801 BTU. The total heat required to completely boil away water whose starting temperature is 92F is 9,996 BTU+ 80,801 BTU = 90,797 BTU.
You need to convert horsepower to BTU transferred to the cooling system and that varies depending on each application. Maybe someone has already determined that for a typical (if there is one :-) ) racing engine. Remember that most conversion charts are for horsepower to BTU per hour. A run on the long course is a lot shorter time-- far less BTUs.
Regards, Neil Tucson, AZ
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Nice maths, Neil. And for what it's worth -- that 80.8k BTU is about what it takes to heat our house for one hour during a nasty blizzard. That puts it in a different perspective, doesn't it - especially when thinking about that much heat generated for disposal in about 2 minutes.
Oh, yes -- by the way, I use the 80.8 figure because I allow the water to still be at about the boiling point after the run ends and the engine is shut down. Good enough for this discussion. :-D
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Great info !!
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A few things that you need to consider when using a plate liquid to liquid heat exchanger. One thing is that the BTUs that it is rated to adsorb are based upon several factors, the first of which is the differential temperature between the two fluids, obviously the greater the differential temp the more heat is transferred that is of course if you have the rated amount of fluid flow going through both sides of the heat exchanger. If you are not moving the fluid through the exchanger at a rate that is fast enough to ensure that the flow is turbulent then your heat exchange efficiency will suffer. Actually the faster the water flows the better. This brings up an additional potential problem. If the exchanger is rated at say 20 gpm flow don't think that you can just attach a 20 gpm nominally rated pump and have 20 gpm. As most if not all water pumps are centrifugal their flow rate drops as the out put pressure is increased, by such things as pressure drop across your plate heat exchanger so you will probably need a much larger pump just to ensure that you are getting enough water going through the exchanger, and that goes for both the engine cooling water and the water from your tank. Neil is correct that the act of bringing water to boiling does require additional heat, the heat of transition, but if you are going to boil your tank water away that would require that your engine water be higher than boiling, not a good idea. I would much sooner go with your concept of a closed tank system with lots of ice,which also requires additional heat to transition from ice to water and properly sized water pumps to insure good flow for both the cooling water and the engine water. I have applied plate heat exchangers a number of times and they can be very efficient and are of course very appealing because of their small size. A liquid to liquid i.e. water to water in this case if properly designed, proper flow rates through both sides of the exchanger will typically be 7-8 times more efficient that an air to water exchanger, also assuming that its water flow rate and the rate of the air passing through it are correctly sized.
Rex
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This is what makes this forum what it is.
Thanks Rex.
I got schooled. :cheers: :cheers: :cheers:
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A few things that you need to consider when using a plate liquid to liquid heat exchanger. One thing is that the BTUs that it is rated to adsorb are based upon several factors, the first of which is the differential temperature between the two fluids, obviously the greater the differential temp the more heat is transferred that is of course if you have the rated amount of fluid flow going through both sides of the heat exchanger. If you are not moving the fluid through the exchanger at a rate that is fast enough to ensure that the flow is turbulent then your heat exchange efficiency will suffer. Actually the faster the water flows the better. This brings up an additional potential problem. If the exchanger is rated at say 20 gpm flow don't think that you can just attach a 20 gpm nominally rated pump and have 20 gpm. As most if not all water pumps are centrifugal their flow rate drops as the out put pressure is increased, by such things as pressure drop across your plate heat exchanger so you will probably need a much larger pump just to ensure that you are getting enough water going through the exchanger, and that goes for both the engine cooling water and the water from your tank. Neil is correct that the act of bringing water to boiling does require additional heat, the heat of transition, but if you are going to boil your tank water away that would require that your engine water be higher than boiling, not a good idea. I would much sooner go with your concept of a closed tank system with lots of ice,which also requires additional heat to transition from ice to water and properly sized water pumps to insure good flow for both the cooling water and the engine water. I have applied plate heat exchangers a number of times and they can be very efficient and are of course very appealing because of their small size. A liquid to liquid i.e. water to water in this case if properly designed, proper flow rates through both sides of the exchanger will typically be 7-8 times more efficient that an air to water exchanger, also assuming that its water flow rate and the rate of the air passing through it are correctly sized.
Rex
Great info Rex. The heat exchanger setup is one option I am considering for our build for packaging reasons.
Can you elaborate as to why you don't want the engine water to be higher then boiling? I know that many forms of motorsport use high pressure cooling system and run engine coolant temps much higher then the average low pressure system. I understand that current nascar systems run near 300*F with no issues all day long. Of course you would build the engine with that in mind but...
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There is nothing wrong with running the engine water at a temp higher than boiling, many race engines are designed for this, not uncommon for NASCAR, F1 etc to run water temps around 230 or even somewhat higher, but the engine needs to be designed for this operating temp, the right coatings, good oil cooling and lubrication and a cooling system that will operate at a pressure high enough to keep the water in liquid form at that temp. I think that NASCAR has set the water system max pressure at 20 PSI just to keep people from going to high. There are also some additional advantages to running high temps , the pressure required for high temp water will provide extra pressure in the block and this can provide additional support to the cylinder walls which on a super charged or turboed engine can be helpful.
As I read Neil's input it appeared to me that he was suggesting that you could uses the heat if transition for water turning to steam as part of your cooling scheme. The challenge with this is that would require that the engine water be significantly higher than boiling and if you want to dissipate sufficient heat to keep the engine temp stable you would need the engine water temp high enough to provide the temperature differential to drive sufficient heat into the cooling water that you are trying to boil. A lot easier just to go with ice in the cooling water and run the engine at under 200 F. Pretty easy to maintain a temp differential of 150 to 170 F and this will drive a lot of heat into your cooling tank water plus the heat of transformation of the ice to water.
Rex