Combined coolant system idea

[obanion]

I was thinking about all the things I need to keep cool on my engine.

1. Engine coolant
2. Transmission fluid
3. AC refrigerant (will be using AC to supercool liquid intercooler fluid)
4. Engine oil
5. Power steering fluid

So many things to mount up front and try and keep cool. Then I figured, maybe there is a way to combine them.

Here's what I came up with.

ONE air/water heat exchanger for everything. A real thick radiator perhaps, but better IMO to build a shroud to match the opening at the front of the car, and get a intercooler core that's 3-4.5" thick to fit in it, and run the fluid through the ends that would have been for charge air.

The water circulated through the intercooler/radiator will lead to a big heat exchanger. The exchanger will be a piece of 5-6" aluminum tubing, with several smaller tubes running through it end to end, one for each of 1-5 listed above. The water coming from the intercooler/radiator won't have it's own tube, rather it's flow will go through the main 5-6" tubing, around the smaller tubes, exiting offset at the other end of the cylinder.

Now the tricky part is the sizing of the individual tubes for 1-5. A larger diameter gives slower flow through speed, and more surface area, acting to increase the heat exchange rate for that particular fluid. I'll crunch more on this later.

So, seem like a neat idea? I like it much better than 5 individual coolers sandwhiched in odd ways, and a lot of airflow going past or around them as a result.

 

[76GMC1500]

Why don't you just have your water pump circulate water to water to tranny fluid, power steering fluid, and refridgerant heat exchangers placed wherever you want them in the car. Set up a cooling water header and run everything in parallel. You may need thermostats on some coolers. You will also need a better radiator and water pump. Our ship uses a similar setup to what I just described. We have a main central fresh water header that runs the length of the engine room, makes a u and runs back down the length of the engine room again. Everything that needs cooling taps off of it from the main engine jacket water coolers to lube oil coolers to the condensor and reduction gear lube. CFW returns to a return header, and is directed to a pair of CFW to salt water heat exchangers. This way only one part of the ships entire cooling system is exposed to salt water.

 

[obanion]

Why do that? Then I'd be building or buying several heat exchangers, which would be scattered around the engine compartment. I like the idea of a single exchanger for all of them.

 

[76GMC1500]

Who said you had to "buy" your heat exchangers. You could make your own with some copper tubing and brazing wire.

 

[SBBlue]

Here's some things to think about. . . .

Let's assume that you have your all-in-one heat exchanger. What temperature are you going to run it at?

1) If it's too low your engine will run at too low a temperature and lose efficiency. If it's high enough to keep the engine happy, it will be way too high for what your air conditioning condenser would like.

2) Consider coolant from the engine that exits the engine taking a certain amount of heat. For argument sake, let's say that the temperature coming out of the engine is 200 deg F, and it is cooled to 180 deg F in the radiator when it is routed back to the engine. If the ambient temperature is 100 deg F, the radiator will see a temperature gradient of about 90 deg F (not exactly, but close enough for argument purposes).

Now consider your new system. What did you say the temperature of the heat exchanger circuit going to be? If it's 100 deg F, then you will need a coolant system heat exchanger about one-half the size of your present radiator (not exactly, but work with me here). But, there's a slight problem. . . . .If your heat exchanger circuit is working at 100 deg F, and the ambient temperature is 100 deg F, then your new radiator/intercooler will have to have infinite heat conductance -- and that's not going to happen.

How about if you split the difference of your heat exchanger fluid temperature, and operate it at 140 deg F. With the lower temperature gradient (190-140) your engine coolant/new cooling system heat exchanger will be about the size of your present radiator. But your new radiator will have to be about twice the size of your old one. So now you have to have three times as much heat exchanger surface as you did when you just used a simple coolant system radiator.

Now since we haven't discussed the oil and transmission coolers, I've underestimated the amount of cooling surface you will need for your new intercooler/radiator system.

I hope I've been clear in what the problems are. Since you are now transferring the heat through two heat exchangers, you will need at least twice the cooling capacity that you have now -- first for the engine coolant/new coolant system heat exchanger, and the second for the new intercooler/radiator device that you have.

 

[obanion]

SBBlue, you missed one important point. The engine coolant at least, will not be freely flowing through the main heat exchanger. The engine coolant flow will still be controlled by the thermostat. Only enough engine coolant will pass through to maintain the thermostat temperature. No need to worry about overcooling that.

Also, you made these claims of heat exchanger surface area but missed the fact that a normal radiator is a air/liquid heat exchanger, but the engine coolant and main coolant will be a direct water/water contact. I don't need a massive amount of surface area. Water has about 25x the thermal transfer rate as water.

 

[obanion]

Additional points.

1. AC refrigerant can't be overcooled. The colder it is before going to the evaporator, the better.

2. The oil, if cooled through the main exchanger (may not need to), will have a thermostat for that too.

 

[mburgess]

Be aware that you will be reqired to maintain a minimum flow of coolant through the water jacket otherwise you will run the risk of developing hot spots within the engine. Could be of merit. With regards to your thick radiator, more surface area is far more efficient that a thick core. In an effort to simlify things you may be over complicating them???? What is the desired effect, weight reduction or greater cooling capacity for certain components. With regards to using a refrigeration circuit to supercool the air intake charge, the temperature of the radiator header tank temperature may be too high to make the refrigerant to water heat exchanger more efficient than the existing condenser coil.
Regards,
MB

 

[JRW261]

I was thinking on the same lines as you were mburgess. It just sounds like he took seperate systems that were very simple to start with and made them alot more complicated, harder to replace, and more expensive to replace.

power steering coolers generally are just steel power steering lines zigzagged back and forth a few times..... as simple as it gets

oil and tranny coolers are generally in the radiator and although they dont cool down below the coolant temp, they cool as well as you want them to in most cases, if not, its very simple to throw an external tranny/oil cooler in front of everything. This setup is also very simple, and if the coils in your rad go bad, just buy one of these seperate coolers and your good to go..... 50 bucks later

most newer cars/trucks are very good at directing air flow through the heat exchangers with shrouds and fans, having them seperated, in my opinion, helps them dissipate heat better and prevents one system from overheating the other as much.

If the condensor goes bad all i need to do is replace just it, or if my radiator clogs, all i need todo is replace it.... not the whole system.

Maybe im just not visualizing your idea that well, I just dont see the benefits other than how it might cool alittle better.

 

[obanion]

After additional thought, I'm starting to agree with the critics. Looking to be more trouble than it's worth.