What Are Pressurized Cooling Systems?

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PRESSURIZED COOLING SYSTEMS

A setup that is becoming ubiquitous in race applications is the pressurized system.  Proper pressurized cooling systems, such as those manufactured by C&R Racing, utilize an accumulator which is similar to a surge tank, but it is built to sustain higher pressures. Accumulators contain a pressure relief valve and a sight gauge to help in bleeding the system, a line from the suction side of the water pump and a return from the radiator. The tank comes with a Pressure Relief Valve (PRV). The PRV is adjustable so it eliminates the pressurized radiator cap. The accumulator is also accompanied by a quick disconnect fitting for the operator to add some pressure above what is created by the expansion of the water.

Pressurized cooling systems

It is generally a limitation of most cooling systems that the cooling fluid not be allowed to boil, as the need to handle gas in the flow greatly complicates design. For a water cooled system, this means that the maximum amount of heat transfer is limited by the specific heat capacity of water and the difference in temperature between ambient and 100°C. This provides more effective cooling in the winter, or at higher altitudes where the temperatures are low.

Another effect that is especially important in aircraft cooling is that the specific heat capacity changes with pressure, and this pressure changes more rapidly with altitude than the drop in temperature. Thus, generally, liquid cooling systems lose capacity as the aircraft climbs. This was a major limit on performance during the 1930s when the introduction of turbosuperchargers first allowed convenient travel at altitudes above 15,000 ft, and cooling design became a major area of research.

The most obvious, and common, solution to this problem was to run the entire cooling system under pressurization. This maintained the specific heat capacity at a constant value, while the outside air temperature continued to drop. Such systems thus improved cooling capability as they climbed. For most uses, this solved the problem of cooling high-performance piston engines, and almost all liquid-cooled aircraft engines of the World War II period used this solution.

However, pressurized systems were also more complex, and far more susceptible to damage – as the cooling fluid was under pressure, even minor damage in the cooling system like a single rifle-calibre bullet hole, would cause the liquid to rapidly spray out of the hole. Failures of the cooling systems were, by far, the leading cause of engine failures.

The C&R Racing NASCAR pressurized radiator system allows teams to run their cooling temperatures as high as 290 degrees F with up to 70 PSI of pressure. These temperatures and pressures are not typically run in a race, but blocking off the front of the grill during qualifying can be the difference between a pole position and  a middle of the pack. These systems are also a great insurance policy if the weather changes, the car gets into a wreck or during nose to tail racing.

The C&R Racing NASCAR pressurized radiator system allows teams to run their cooling temperatures as high as 290 degrees F with up to 70 PSI of pressure. These temperatures and pressures are not typically run in a race, but blocking off the front of the grill during qualifying can be the difference between a pole position and  a middle of the pack. These systems are also a great insurance policy if the weather changes, the car gets into a wreck or during nose to tail racing.

And for these Cooling Systems Vr-12 recently launched its new product the VR-12 Racing Coolant, specialized for race car cooling systems.

VR-12 Racing Coolant is a non-glycol racing coolant, making it safe to be used in all racing venues and classes. VR-12 Racing Coolant doesn’t contain glycols, poly-glycols, phosphates, or nitrates. VR-12 Racing Coolant is a water based product, making it both biodegradable and eco-friendly. VR-12 Racing Coolant consists of a combination of deionized water with state of the art OAT (Organic Acid Technology) formulation of “Add Packs” that provide 100% protection against rust, corrosion, electrolysis, oxidation, and cavitation. VR-12 Racing Coolant protects both old and new aluminum alloys, as well as metal and polymer (plastic) components. (This product is not an antifreeze, and does not offer freeze protection).

VR-12 Racing Coolant is designed to provide the competitor the maximum heat transfer at the most extreme temperatures, allowing your engine to function at the highest possible horsepower without overheating.

VR-12 Racing Coolant is designed by racers, and proven to work for both racers, and engine builders.

You can find more information of VR-12 Racing Coolant and other Freeztone Products at www.vr-12.com.

From: appliedspeed.com and en.wikipedia.org

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