kcelectronics Posted October 17, 2012 Share Posted October 17, 2012 I was looking into buying an aluminimum radiator when I found this information, don't know if this has been posted before? The Basics The boiling point of water is 212 degrees Fahrenheit at sea level. The higher you are above sea level, the lower the boiling point of water, and the sooner water will boil. Engine cooling systems are pressurized to raise the boiling point of water. For every pound of pressure in the cooling system, the boiling point of the water will raise 3 degrees. Atmospheric pressure along with outside temperature and humidity also affect the boiling point of water. Water boils when the atmospheric pressure and vapour pressure become equal. Radiator Construction The heat transfer ability of metals (the ability of the metal to transfer heat through itself) helps to determine the efficiency of a radiator. On a scale of one to 100, silver is highest in efficiency with a rating in the upper 90's. Copper is also in the upper 90's. Brass (which is an alloy) has a rating in the upper 40's as does aluminium. Lead which is often used to bond brass and copper together has rating in the 20's. When comparing copper radiators to aluminium radiators, remember that copper transfers heat through itself better than aluminium, so copper is better at moving the heat away from the tubes inside of the radiator. Radiators that are made of copper and brass are generally more efficient than the same size aluminium radiator. Aluminium radiators are better at transferring heat out of the liquid coolant. Comparing the two types of radiators with the same dimensions; aluminium radiators have the advantage of being physically lighter in weight. With increased airflow an aluminium radiator can be made to be as efficient as a copper radiator. Keep in mind...you must have the airflow to make aluminium radiators work! There must always be a drop in air pressure between the front side of the radiator and the engine side of the radiator. It is this pressure drop that helps draw the ar through the radiator. High pressure on the engine side of the radiator can greatly reduce... even stop completely, the flow of air through the radiator. Summary Plain water is the best dispersant of heat there is. Water is also one of the most destructive liquids you can put into the cooling system. Most all of the problems associated with cooling systems (corrosion, electrolysis, rust, etc.) are related to water. Corrosion reduces the efficiency of the cooling system by reducing the volume of coolant within the system and by restricting the flow of the coolant itself. Antifreeze is added to the cooling system to prevent the freezing of the water in winter and carries the additives necessary to correct the pH of the water which helps to prevent corrosion and electrolysis. The antifreeze itself provides no cooling benefit. The faster you drive, the more air that flows thorough a radiator is Not true. No matter how fast you drive, the pressure against the front of the radiator is equal to about 40 percent of vehicle speed. What happens to airflow after it gets through the radiator is just as important as the amount of air that flows through the radiator in the first place! In most all applications...a thinner radiator works best and will cool better than a thick core radiator because of the increased airflow available through the thin radiator. Might hold on to the radiator I have now and save some bucks LOL Quote Link to comment Share on other sites More sharing options...
LanceVance Posted October 17, 2012 Share Posted October 17, 2012 Source? Quote Link to comment Share on other sites More sharing options...
kcelectronics Posted October 17, 2012 Author Share Posted October 17, 2012 http://www.fifthaveinternetgarage.com/tech_tips/tech_tips_which_rad_is.html Quote Link to comment Share on other sites More sharing options...
roger280zx Posted October 18, 2012 Share Posted October 18, 2012 (edited) The faster you drive, the more air that flows thorough a radiator is Not true. No matter how fast you drive, the pressure against the front of the radiator is equal to about 40 percent of vehicle speed. So the faster you drive the more air flow through the radiator... Right. Got it. Edited October 18, 2012 by roger280zx Quote Link to comment Share on other sites More sharing options...
johnc Posted October 18, 2012 Share Posted October 18, 2012 The faster you drive, the more air that flows thorough a radiator is Not true. No matter how fast you drive, the pressure against the front of the radiator is equal to about 40 percent of vehicle speed. That is an odd statement. To rephrase it: "The atmospheric psi in front of the radiator is equal to 40% of the vehicle's velocity." I do not know of any way to convert psi into velocity give the information in the sentence. Now, if the sentence is supposed to read: "The velocity of the air flowing through the radiator is equal to 40% of the vehicle's velocity." then we have something that can be checked. Quote Link to comment Share on other sites More sharing options...
FricFrac Posted October 30, 2012 Share Posted October 30, 2012 ... and the information about thermal conductivity is wrong. It's pretty common knowledge that aluminum is an excellent conductor of heat which is why it's often used for heat sinks in computers and other electronics. Copper is one of the best but because of cost/performance considerations we usually see aluminum for transfering heat. Aluminum is about half as thermally conductive as copper and brass is half as thermally conductive as aluminum. So for our application an aluminum rad will be much more efficient than a brass one. Ever seen a brass intercooler? http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html Quote Link to comment Share on other sites More sharing options...
johnc Posted October 30, 2012 Share Posted October 30, 2012 Ever seen a brass intercooler? Yes. Diesel trucks. They also make them out of Stainless Steel. Inlet temps of many diesel engines are high enough that aluminum intercoolers are unreliable. Same is true of some very high horsepower (over 1,000 hp) automotive racing applications. Intercooler failures have been fixed and the temperature delta impoved significantly by going to a copper/brass intercooler. http://www.trucktrend.com/features/tech/163_0210_air_coolers_diesel_engines/index.html Quote Link to comment Share on other sites More sharing options...
heavy85 Posted October 31, 2012 Share Posted October 31, 2012 It is my understanding that CuproBraze technology is the key. These are not your fathers heats exchangers and that 'CuproBraze' process results in much higher efficiency than than standard old school copper/brass radiators. Quote Link to comment Share on other sites More sharing options...
(goldfish) Posted November 2, 2012 Share Posted November 2, 2012 ... and the information about thermal conductivity is wrong. It's pretty common knowledge that aluminum is an excellent conductor of heat which is why it's often used for heat sinks in computers and other electronics. Copper is one of the best but because of cost/performance considerations we usually see aluminum for transfering heat. Aluminum is about half as thermally conductive as copper and brass is half as thermally conductive as aluminum. So for our application an aluminum rad will be much more efficient than a brass one. Ever seen a brass intercooler? http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html Based on the chart show % composition of other alloys, that makes me think that the pure Aluminum is just that, pure. In that case it does not relate very well to the Al radiators. Quote Link to comment Share on other sites More sharing options...
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