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help I need a heat exchanger expert

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Posted by: jmics19067

Ok my problem is pretty much boredom and being cheap so comments like just buy a new one won't work here

ok the question is How come radiators in have oval runners with the fins being that sliced up crinkled material. While heat exchangers<same basic principal> have rather large round tubing runners with pretty much straight fins?

what kind of problems would any one foresee if I made a radiator with round runners and straight fins? Do heat exchangers not cool as efficient as radiators?


Posted by: dklink2000

Your going to make a radiator?


Posted by: RM_guy

I'm no expert but it has to do with surface area. The more surface you have to radiate heat (or absorb it), the more efficient it will be.

The heat exchangers that you are referring to probably have round tubing and flat fins because it's cheaper to make. As a result they have to be larger to get the same surface area as one with "crinkled" fins and oval tubing.

Making your own radiator without the same surface area may not cool your bike as well and you’ll experience more overheating.


Posted by: dklink2000

jmics19067,

I think your right in thinking that a heat exchanger is just not as efficient as a radiator.


Posted by: jmics19067

Quote:
Your going to make a radiator?


well it would be more of a heat exchanger . But yeah why not heh welding/ fabricating is not only a part of my job but a hobby. 450$ to replace a radiator that is waffled and covered with epoxy to stop the leaking as compared to maybe 70$ worth of material<over inflated price but...> and a weekend in the garage playing with my torches. The local Radiator shop who repairs aluminum ones told me mine are junk. Told me they wont even try to fix it. the Only way I see me fixing these leaks is to remove the offending cores that are leaking and crimping/soldering them shut.

On my bike the radiators are spaced out away from the frame so I have the noble concept of being able to make my radiators wider which might help in the surface area department.
wieght is not particularly an issue here so I was going to make a stronger box frame around the core to help keep future damage down.

thanks all for the input if I feel like playing I might try making one out of brass<cheaper and easier to make> with a steel frame to see how they might work. I guess I am going to have to make up some type of temp gauge at the water pump inlet to see if they work well enough.

thanks again


Posted by: MXTex

A radiator is a heat exchanger. They both operate off of the 2nd law of Thermodynamics: "Heat travels from a high temperature body to a lower temperature body". The fins you speak of obviously increase the surface area exposed to the lower temperature body. There are several factors that contribute to the differences you note between the two units you describe. Cost of manufacture is one, operating temperature is another, and weight another significant contributor. Bottom line recommendation, send your radiator to Mylers in Utah. They will fix anything. I've used them on several occasions with excellent results.


Posted by: jmics19067

Quote:
Bottom line recommendation, send your radiator to Mylers in Utah. They will fix anything. I've used them on several occasions with excellent results.


Well that sounds like definately great advice can you give me more info please? Do they have ads in magazines so i can get an address? Do they charge a flat rate to repair or is it by the hour of labor?

Unfortunately it doesn't help with my boredom though :confused: I was contemplating the idea of having an oil tube running thru the radiator much like a transmision cooler in a car radiator. Not sure if would help any with my clutch feel fading but it wouldmake for an interesting conversation piece plus the fact that I would be in garage keeping occupied as compared to setting around scheming up kookier ideas


Posted by: MXTex

They are listed in the back of most MX magazines. Their phone number is: 800 367 7699 Their address is: 8414 S. McDowell Ct., West Jordan, UT 84088

Cost is dependant on severity of damage. Minimum cost is $35.

They would probably have some good feedback for you on constructing a custom radiator. Running an oil cooler could be a cool idea. Good luck.


Posted by: RM_guy

It sounds like an interesting project. It never hurts to experiment and you never know what you might come up with. It sounds like you’re already into kooky ideas but how about a cooling condenser to make the gas colder as it enters the carb. You might gain about .002367298 horse power (just a quick estimate)

I’d still keep the repair option open, just in case


Posted by: MoO_coW

Im not an expert on this or anything but isn’t the cylinder made to be at a certain temperature, if it was cooler from a larger radiator couldn’t that cause a seizer or if it was warmer couldn’t that cause piston slap? I guess it depends on the difference and all but I think making a radiator is alot harder than it seems(and that’s pretty hard) More power to ya on it though


Posted by: DEANSFASTWAY

Hey JIMICS howsit brutha ? You know what might work well is a set of CR500 radiators there surface area is larger than on your YAM . I used to use these on my OHLINS 94 YZ 360 . as for making a rad /heat exchanger device , I knowa guy in Flemington Nj that will build you any type of radiator , exchanger ,intercooler etc The company is ARTs radiator in Flemington Nj just down the road from where the speedway was .He makes custom rads for race cars trucks bikes etc. But hes not cheap , but his stuff is quality /sano . I was always wondering if having thicker tubes and increasing the flow though the rads helps pull heat as opposed to thinner tubes and the coolant would stay in rad a little longer to help pull more heat out . I know that in some circumstances we have to slow down pumps and put restrictors in systems so they dont flow so fast (the heat is never dispelled ) . Also there are some racers that like to run straight anti freeze and some like to run straight water. The A/F guys say the A/F lowers the boiling point and the H20 guys say that the water pulls and rekeases the heat more easily . Then there are the additives out there that one of them (Engine Ice I think) seem to be nothing more than soap. Maybe its like whsat came first the chicken or the egg . I can tell you one thing JIMICS If you find yourself a Ohlins /Noleen 360 kit you will have yourself a nice project on your hands that will keep you occupied in your garage for many a night and the results will be very impressive as that thing rips. And those Yzs that you have are really good bikes. I have repaired quite a few radiators but yous kind of sounds like its too far gone. Have you tried any Dirt bikre salvage yards for a used one? What do you think sheds heat better copper or aluminun It seems in dirt car racing the really good and best rads are heavy copper and the cheaper alum rads arent as popular, and are more for like budget guys . A rad for a dirt madified ccosts $ 500 I know I just bought one because the Weind water pump wasnt happy at around 7400 RPM . Have a good one Jimics DEAN


Posted by: bushpilot

There is an article in the August 2002 issue of Street Rodder on page 134. It show a method of building a radiator/heat exchanger.

Wayne


Posted by: jmics19067

Quote:
Running an oil cooler could be a cool idea


heh all puns are greatly appreciated
Quote:
What do you think sheds heat better copper or aluminun It seems in dirt car racing the really good and best rads are heavy copper and the cheaper alum rads arent as popular, and are more for like budget guys


Both transfer heat extremely well but I am not sure which one is actually better I find it odd that the lighter one is cheaper but copper is more expensive than aluminum . The copper should be a lot easier to solder together though. I am only going by the fact that enough aluminum oxide to make trouble while brazing or welding with a torch occurs in minutes compared to other materials taking hours. Never tried an aluminum solder yet so I am not so sure how it's fluxes work.


Posted by: jmics19067

Quote:
Im not an expert on this or anything but isn’t the cylinder made to be at a certain temperature, if it was cooler from a larger radiator couldn’t that cause a seizer or if it was warmer couldn’t that cause piston slap?


Although having too much or not enough cooling is indeed a problem but unless you are running a KTM witha thermostat I dont think you really have much control. I am sure cylinder and radiator temps are greatly different if riding thru tight sandy bottomed woods on a hot day compared to a high speed hard packed run on a cool day.
Quote:
There is an article in the August 2002 issue of Street Rodder on page 134. It show a method of building a radiator/heat exchanger.


that is a great bit of help thanks!!!!! will have to pick up that mag and take a read thru.


Posted by: MXTex

I would recommend going with copper tubes for the reasons you state. In the mid 80's, a major Air Conditioning Manufacturer switched to aluminum tubes within the coils of their residential condensing units; for cost reasons. Repairs of these aluminum coils were very difficult. Eventually, this manufacturer switched back to copper; which is much easier to repair.


Posted by: NVR FNSH

The 'crinkled' fins & ovalize tubing help increase turbulence which increases heat transfer. I worked at AlliedSignal in the heat exchanger design group - A/C for airplanes - and at Garrett Turbochargers where I got to see intercoolers being designed/built/tested. We had a library of fin designs to choose from depending on the various constraints - size/weight/effectiveness/cost/damage susceptability etc. High effectiveness heat exchangers pretty much always used offset fins for the increased heat xfer.

Try finding a larger core (CR500 as mentioned previously) and building your own tanks. I suspect the custom radiator shop mentioned earlier specs a core from a catalog - Modine or others - and then builds the tanks for the applicaton.

Brian


Posted by: motometal

the theory that "if the fluid flows too fast it won't transfer heat" is sketchy, at best. Creating air pockets or hot spots in a system is bad, and the fluid must wet the surface for optimum transfer.

Otherwise, a greater delta T (difference in temp between coolant and object being cooled) will provide more cooling.


Posted by: jmics19067

Quote:
Try finding a larger core (CR500 as mentioned previously) and building your own tanks.


that definately sounds like a great idea I might shoot for. Definately sounds a lot easier than trying to manufacture my own, just modify an existing used one for my "experiment".
I was thinking of using three 1/4" round tubing spaced 1/4" behind each other next to two 1/4" tubes offset and so on down the width of the core. With .030 sheets spaced 3/16" on top of each other to make the fins for my actual core. Which would be quite a bit of work in itself let alone making some type of jig to hold it together straight for me as I assembled it.

let alone the fact that I can probably get the cr 500 louvers to snap right in easier than compared to trying to make my own or make the ones I have work.

Thanks for all the great advice and comments, when and if I get this project off the ground and finished I will be sure to post pics and comments on the completed project. probably around next spring.


Posted by: EricGorr

The most interesting radiator design that I've ever seen for a motorcycle, originated in Russia in the early 1990s. This small company used oval shaped extrustions and machine tiny fins to increase the surface area of each tube. Plastic tanks were fitted to the top and bottom of the tubes, epoxied into place. The radiators were made to be universal, with two different lengths for large and small bikes. The radiators used a ridgid frame, similar to aftermarket protection kits. Then brackets were fastened to the radiators to adapt to different types of bikes. They were a bit heavy but worked excellent. I still have a sample in my garage. Eventually the company in Russia became discouraged because they appointed an English marketing agent who didn't have any clout in the American market.
CR, a company that markets radiators for race cars has also looked at the dirt bike market. Considering how cheaply made Japanese radiators are made, and the premium price charged by the OEMs, you'd think that somebody would jump into the market?


Posted by: red rulz

Why not get an old car radiator from the recker and cut the cors to the size you need, then get some copper sheet and make the tanks then solder together- cheap and almost guarenteed to work.


Posted by: olddirtbaginmt

jmics:

Mylers in Utah has worked on radiators for me in two different instances and with excellent results - one was even messed up from having it worked on (experimented with!!). Seems to be a very honest individual(example: a friend of mine does not like C.O.D. and sent $75.00 cash to him with his radiator, Myler repaired it-sent back the radiator and his change in cash). His charges are a minimum of $35.00 and a maximum of $75.00; if he can't save the radiator, all it costs you is the shipping.

Tom


Posted by: jmics19067

Eric Gorr and Red Rulz just gave me a very interesting concept. If and when I tackle this project I am going to look at making the radiator out of an old auto core that will fit in and helped be held in by them "extreme guards" made by Devol. Heck nowadays cars have aluminum cores with plastic tanks glued on anymore so hopefully making the radiator shouldn't be a lot of trouble and be relatively light. Then if I make it so that the radiator gaurds help sandwich the radiator to the bike ,bob wieght stress at the mounting points will be less of an issue with the addedprotection to avoid this mess again.
I am going to try this approach I think, and after I end up with a cluttered work bench full of scrap radiators stuff and my fingers glued together I will definately give Mylers a thought

Thanks again all



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