What is the Advantage and Disadvantage of Custom Engine Cooling System

Liquid cooling or water cooling is an alternative to traditional air cooling. It involves circulating coolants across the components of a computer or device to remove excess heat. Take note that computers generate heat. But certain circumstances such as an unfavorable external environment or using too much processor resources can result in overheating. Excessive heating can affect the performance of the device or damage its hardware components.

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Most desktop and laptop computers are well-equipped with an air cooling system built for their particular hardware specifications. There are certain situations in which air cooling is not ideal. These include laptops with smaller form factors or desktops that use powerful main processors and discrete graphic processors. Devices such as smartphones are also not ideal for air cooling because of their size. This is where liquid cooling takes the spotlight.

Pros of Liquid Cooling: Advantages and Main Benefits Over Air Cooling

1. Less Clutter and More Space

Traditional air cooling uses fans. A typical air-cooled computer has several fans installed inside the chassis. These include fans for drawing air inside and outside, specific fans for the graphics processor, and other specific fans for the central processing unit.

More fans are needed for a customized PC with more powerful discrete graphics processors or overclocked central processors to improve heat dissipation. This means consuming more real estate inside the computer chassis. This also makes air cooling unsuitable for compact computer chassis, slim or lightweight laptops, and other portable devices.

One of the advantages of a liquid cooling system is that it does not take up too much space because of its smaller physical profile. This allows building smaller devices or computers that can be populated with more or advanced hardware components.

2. Noise-Free Operation

Fans generate noise. This noise becomes more audible when the device is overworked. Installing more fans also means producing more noise. Another advantage of liquid cooling over an air cooling system is that it does not generate the same noise.

A liquid cooling system uses a motor to circulate the coolant around and across the internals of the device. The system includes a low-powered fan. Some hybrid systems integrate small fans to improve further the ventilation inside the device. Nonetheless, compared to air cooling, both the motor and low-powered fans do not generate discernible noise.

The absence of noise is an advantage in certain situations or use cases. A silent or near-silent computer allows a user to work, play games, or consume media without distraction. This increases the comfort and enhances the overall user experience.

3. Better Overclocking Potential

Overclocking a processor or raising its frequency beyond the stated stock frequency is popular among enthusiast-level consumers and computer builders. The downside of this is that it results in higher power consumption and more excessive heat generation.

Another notable advantage of liquid cooling is that it is more efficient in removing excess heat. This advantage comes from the fact that water or a particular liquid coolant has higher heat capacity, density, and thermal conductivity than air. This allows the heat management and cooling system to transfer more heat over greater distances.

Hence, because of it is more efficient than air cooling, it also increases the overclocking potential of a processor. A user can raise the clock speed of a processor nearer to its limits with a more effective and efficient heat management and cooling solution.

4. Cooling Specific Components

A higher degree of cooling specification is another benefit of liquid cooling. This means cooling specific components of the computer to a greater degree than in traditional air cooling. It allows a more targeted cooling for a more efficient heat removal.

Liquid cooling allows heat dissipation from critical spots or areas within the device. Users can choose to cool specific components that are more prone to overheating. Some examples include the main or central processing unit, discrete graphics processor, internal solid-state drive or hard disk drive, voltage regulator modules, and power supplies.

Remember that this system is more compact and has a smaller footprint. Air cooling units are bulkier. Most setups focus on the CPU and GPU. A user can still place a fan near a hardware component but this means a more messier and bulkier setup.

Cons of Liquid Cooling: Disadvantages and Drawbacks Versus Air Cooling

1. More Expensive to Implement

One of the notable drawbacks or disadvantages of a liquid cooling system over an air cooling system is cost. It is more expensive to implement. Take note that cooling fans are cheaper and are more available in the market than liquid cooling components.

The components from cars and aquariums were the basis for earlier implementation. There are now specific liquid cooling components for computers. The overall cost for implementing a liquid cooling system scratch ranges from 300.00 to 500.00 U.S. dollars. An air cooling system has costs ranging between 100.00 and 200.00 U.S. dollars.

Self-contained liquid coolers are a cheaper option with prices starting at USD 60.00. These are similar to cooling fans. A cooling system based on these liquid coolers has a limited degree of modification compared to a full-blown liquid cooling system.

2. Installation Complications

Implementing a liquid cooling system from scratch also requires a foundational understanding of electronics and thermodynamics. This is another disadvantage. Remember that a cooling system should be able effective and efficient at removing excess heat.

The installation of an entire liquid cooling system also requires more involvement compared to the process of installing aftermarket air coolers. Specific cooling fans are often placed atop the processors and in the exists of the computer chassis. The components of a liquid cooling system require connecting tubes, wirings, and proper placement loops.

Safety is also an important consideration. A user must ensure that the system is resistant to possible leaks. This is done through pre-installment testing. Drops from water or liquid would damage the electronic components and are also a fire hazard.

3. Maintaining and Upgrading

It is also important to note that this cooling system also requires more maintenance than an air cooling system. A user needs to monitor the coolant levels and temperatures regularly. There is also a need to refill coolant and bleed trapped air from the tubes.

Another drawback is that a custom liquid cooling system can be less flexible when it comes to hardware upgrades. Replacing the CPU or GPU would require modifications to the entire setup. This means repositioning tubes and loops or even starting from scratch. Liquid coolers and air cooling systems are more adaptable to hardware upgrades.

There is also no guarantee that the system can result in a performance boost despite being more effective and efficient at dissipating heat. This transpires when components are at bottlenecks. No amount of heat management can improve their performance further.

4. Specific Leakage Concerns

A poorly implemented liquid cooling system is likely to result in leaks. The liquid coolant can corrode the metal parts of electronic components. The pressure inside the tubes can also build up due to too much heat absorption. This can result in leakage.

The aforementioned means that another disadvantage of liquid cooling is that it is unsuitable for those who have little to no experience. A user must ensure that the entire setup is free from errors or risks. There should also be some form of contingency in case a leakage transpires. It is important to note that a single drop of liquid can ruin an electronic component.

Even the faintest likelihood of leakage makes a liquid cooling system an unideal choice for the average consumer. It is not advisable in situations in which an air cooling system is more than sufficient as a particular heat management and cooling solution.

Conclusion: Which is Better? Liquid Cooling or Air Cooling?

Implementing a liquid cooling system might be one of the hallmarks of building a customized personal computer. Those who are serious about their custom-built personal computers should carefully consider what cooling system works best for them.

Choosing between liquid cooling and air cooling boils down to requirements or usage needs. Take note that air cooling is a more practical solution for the advantage users. This is true for individuals with budget constraints and limited expertise.

A liquid cooling system is ideal for powerful personal computers used for resource-intensive tasks such as PC gaming and video editing. It is also suitable for overclocked processors or multiple graphics processors and coprocessor setups.

Processors can burn under too much stress or extensive high-performance applications or tasks. Effective and efficient heat management and cooling can extend the lifespan of these hardware components and improve their performance further.

Nevertheless, based on the advantages of liquid cooling, it works better than air cooling and is an ideal solution in situations in which air ventilation is impossible to introduce. However, because of its disadvantages, it is not suitable in most use cases.

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Additional: A Note on Heat Pipe and Vapor Chamber Systems

There are  two sub-types of liquid cooling systems. These are heat pipes and vapor chambers. A heat pipe is a heat-transfer device that works based on the principles of thermal conductivity and phase transition. It transfers heat from a source to another solid interface. Heat is removed from the heat source through a fluid that converts into gas when heated, travels along the pipes to the cold surface, and condenses back into its liquid form as it cools.

A vapor chamber cooling uses a different design approach. It does not use separate pipes. It uses its liquid-filled body to cool the heat source. It is important to underscore the fact that heat pipes move heat while vapor chambers spread it. The general rule is that heat pipes should be used when moving heat away from the source and vapor chambers when spreading it. Each has its respective advantages or benefits and disadvantages and limitations.

Probably no other aspect of all that noise on the far side of the firewall takes up as much of our time as engine cooling. Seemingly everyone has chased hot oil or cylinder head temperatures at some point, and among the more theoretical, the air- vs. water-cooled debate is a never-ending source of verbal sparing.

Perhaps a good place to start is why engines must be cooled in the first place. After all, the whole idea is to make heat and expand air in the combustion chamber, so wouldn’t it be best for the engine to run as hot as possible? The short answer is yes—witness jet engines—but we don’t have practical materials to build such piston engines out of.

The Great Debate

As just noted, the big question is whether to cool with air or a liquid, namely water. Like all great debates, each side has excellent reasons for their prejudice, but we’ve come to view the question on whether one is engine- or airframe-centric.

Air cooling is easier for the airframe thinker. Air is free, it’s what we fly through. “Water cooling an airplane engine makes as much sense as air cooling a submarine,” they say. And the core of such thinking is valid; engine heat is rejected straight to the atmosphere. That’s where the heat is headed no matter if you water cool or air cool, so shedding directly to the atmosphere offers the lightest, simplest rejection path. Those designing airframes are pleased to ignore the complexities and weight of radiators, water, plumbing, and providing the access to service leaks.

On the other hand, engine people admit water cooling is more complex, but makes for a more efficient engine. They point to a cornucopia of engineering details facilitating higher cylinder pressures and more even temperatures, and say this is the way.

All said, today’s typical general aviation engines by both engineering truth, but increasingly by accident of historical precedent, occupy a niche currently well served by air cooling. But in our opinion, water cooling would be the best way forward should there ever be an economically viable future in advancing general aviation engines. That makes both methods worth our study.

Air Cooling

Simplicity is the core attribute of air cooling. Heat is radiated directly to the atmosphere by increasing the surface area of the engine via cooling fins on the cylinders and cylinder heads, the remainder being oil cooled.

It’s not enough to leave the engine hanging out in the breeze, however. Air must be controlled as it passes around the cylinders to ensure the correct air mass, speed, and proximity to the cooling fins. As cooling air enters the cowling on a typical horizontally opposed engine, it is fenced in around the top of the engine by baffles tipped with flexible baffle seal material that mates the baffles to the cowling. Thus pooled in what is sometimes called the upper deck, the air slows and increases pressure.

The only way out of the upper deck is via the cylinder fins. Various cuffs and inter-cylinder baffles force the air to wrap around the cylinders as much as practical, then allow the air to exit to the lower deck, which is simply the area under the engine. The lower deck is vented to the atmosphere by the cowling exit, which may have a hinged cowl flap to vary the size of the exit and thus the volume of air passing through the system.

Clearly it is imperative to have high air pressure in the upper deck and lower pressure in the lower deck or airflow will be compromised or even flow backwards out the cowling inlet.

A crafty method of increasing cooling air velocity, and thus lowering the pressure in the lower deck, is exhaust augmentation. Cooling air exits the cowling via a channel—”boom tube” among friends—into which the exhaust system empties. The high-energy, fast-moving exhaust adds velocity to the exit air and replaces cowl flaps in the process. Beechcraft, Grumman, and Formula One racers have used augmenters to good effect.

Aside from cowl flaps and rubbing of the baffle seals against the cowling, there are no moving parts in air cooling systems so maintenance is pretty much confined to replacing chaffed or cracked cylinder baffles and seals. And such is the air-cooling advantage; it takes readily available air, guides it past the engine with a few pieces of sheet metal, and asks nearly nothing in weight or maintenance.

The primary disadvantage of air cooling is it limits the engine’s specific output. Eventually you run out of surface area to reject heat through, thus limiting how much fuel the engine can burn. Limiting fuel limits power, and you end up with large-displacement, fuel-inefficient engines to make sufficient power.

There are exceptions, naturally. The Pratt & Whitney R- and R- radials employed forged, not cast, cylinder heads with thinly machined, not cast, cooling fins. This is an expensive way to make cylinder heads, but was one way of getting enough surface area to cool an engine making 0.89 hp/cu. in. of displacement. Another example was the Wright , an even more extreme engine with many teething and operational issues. Capable of 1.04 hp/cu. in., the cylinder has very thin corrugated sheet aluminum stuffed between the usual cast cooling fins to increase surface area. By contrast, a 180-hp O-360 Lycoming makes about 0.50 hp/cu. in. and doesn’t come close in sophistication or ability to shed waste heat as the old radials.

Workarounds for improving air cooling are spraying water over the engine for a powerful evaporative effect. One could say this is a form of water cooling, but in any event, the method is superb in sprint applications (racing, aerobatics, specialized climb scenarios), but requires too much water for the typical endurance work.

And it’s not just maximum power that’s affected by an air-cooled engine’s limited thermal efficiency; fuel consumption and range are compromised as well.

Shedding heat as they do directly to the atmosphere, air-cooled engines are more at the mercy of atmospheric variables. Large extremes in the sky’s temperature and density mean an air-cooled engine must withstand great variations in the rate of cooling. Yes, cowl flaps go far in controlling the rate of air cooling, but they can only do so much. The result is air-cooled engines expand and contract like balloons, so internal engine tolerances are goose-loose and operating limitations—avoiding rapid low-power descents for example—are tighter.

And while it’s not a law of physics, it does seem we have some to learn in general aviation about efficiently designing, sealing, and maintaining air-cooled engine cooling systems. If a water-cooled engine leaks coolant, it gets fixed; if an air-cooled engine leaks air through its upper deck, few people notice and fewer yet do anything about it. The result is designers opt for larger capacity, draggier air-cooling systems than we might need.

Water Cooling

Liquid-cooled engines jacket the cylinders and cylinder heads with water. Heat is absorbed by the water, which is pumped to a radiator where the heat is shed to the atmosphere. An engine-driven pump circulates the water, and a thermostat sets the coolant’s minimum temperature.

Water is an excellent heat transfer agent and is the working fluid in almost all liquid cooling systems, although there are non-water fluids as seen in some Rotax engines. Where water is used, ethylene glycol is added as a corrosion inhibitor. Raising the pressure of the system via a spring-loaded vent increases the water’s boiling point and thus the system’s efficiency (the hotter the coolant and the colder the air passing through the radiator, the more heat is transferred per unit of time). Note, however, that if the coolant is run at very high temperatures, eventually the oil becomes the main coolant because it’s colder upon entering the engine and thus will absorb more heat.

Liquid cooling’s major advantage is water is far denser than air. A smaller volume of water can transfer more heat than the same volume of air, so more cooling power can be packaged tightly around the engine. Also, dense water takes longer to warm up and cool down, thereby absorbing temperature spikes and localized hot spots much better than air. The resulting thermal stability yields a virtuous circle of improvements in engine design that result in higher specific output.

Greatest of these are tighter piston-to-cylinder and piston ring gap clearances. The better sealed cylinder holds more cylinder pressure for greater power and efficiency, lets less oil past the rings to reduce detonation risk, dirties the oil more slowly, and means less oil needs to be carried aloft. Tighter pistons literally run quieter, enabling more ambitious knock sensor strategies in computer-controlled engines, too.

Another advantage is the ability to package greater cooling power around hot spots such as completely around the exhaust valve seat. Sophisticated internal water flow paths now possible from computer modeling also mean more even temperatures across the cylinder head. Engine temperature growth is thus vastly better controlled with liquid cooling; more precise tolerances throughout the engine are therefore possible. Again, it all adds up to more power and efficiency.

Liquid cooled engines can also be more physically compact and, even more importantly, rigid. That’s because the cylinders and cylinder heads can be cast in monolith banks rather than cantilevering out from the crankcase like a bunch of quivering porcupine spines. Because no cooling fins are needed, the cylinders can be more closely packaged, shortening the crankshaft—more rigidity—and the engine overall.

Need we also point out liquid cooling allows narrower form factors? A quick comparison between a V-12 and a radial will set that picture. That said, the now overwhelming realities of the horizontally opposed layout in general aviation means we won’t be seeing many razor-thin new inlines anytime soon.

At the heat rejection end, to the airframe designer, a radiator is portable around the airframe and air can be efficiently ducted to it. Tricks such as the Meredith effect can reduce cooling drag, as can packaging the cooling exits into low pressure areas. Doing the same with air cooling is more difficult in practice.

Downsides to water cooling are its increased weight, complexity, and initial cost. There’s no getting around the increased weight, although greater fuel efficiency might recoup some of that in larger aircraft. Ditto complexity as a radiator, piping, connections, a pump and thermostat are all “extras” versus air cooling. But we must say the sometimes half-baked air-to-water cooled conversions of traditional Continentals and Lycomings result in needless complexity with silly cylinder-to-cylinder hose connections, externally-mounted thermostats, and other engineering affronts not found in a purpose-built liquid-cooled engine.

Which brings us to a takeaway idea regarding water cooling: it takes a thoughtful integration of a purpose-built water-cooled engine into an airframe designed around it to realize all of liquid cooling’s advantages. And in our general aviation reality simpler, slightly less efficient air-cooled engines are often the lighter, less expensive, easier to live with choice.

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