Water cooling is a method of removing heat from industrial components and equipment. In contrast to air conditioning, water is used as a heat conductor. Water cooling is commonly used to cool the car's internal combustion engines and large industrial facilities such as steam power plants, hydroelectric power plants, petroleum refineries and chemical plants. Other uses include cooling machine-gun barrels, cooling lubricating oil on pumps; for cooling purposes in heat exchangers; cooling products from tanks or columns, and more recently, cooling various key components inside high-end personal computers such as CPU, GPU, and motherboards. The main mechanism for water cooling is convective heat transfer.
Video Water cooling
Nomenklatur
Cooling water is water that removes heat from a machine or system. Cooling water can be recycled through a recirculating system or used in single pass disposable cooling (OTC) systems. The recirculation system can be open if they rely on cooling towers or cooling pools to remove heat or closed if heat dissipation is done with the loss of evaporative cooling water. The heat exchanger or condenser can separate the non-contact cooling water from the cooled fluid, or the cooling water of contacts can be directly punctured on items such as circular saws where phase differences allow for easy separation.. Environmental regulations emphasize reducing the concentration of waste products in non-contact cooling water. Maps Water cooling
Benefits
Water is cheap and non-toxic. The advantages of using water cooling through air cooling include specific thermal capacity, density, and higher thermal conductivity of water. This allows the water to transmit heat to longer distances with much less volumetric flow and reduce the temperature difference.
To cool the CPU cores in computing equipment, the main advantage of water cooling is that it is capable of transporting heat from the source to the secondary cooling surface to allow a larger and more optimally designed radiator than a relatively inefficient small fin fitted directly to the heat source.
The water jacket around the engine is also very effective when turning off mechanical sounds, which makes the engine calmer.
Disadvantages
Cooling water often adds considerable levels of complexity and cost to the design, with cooling systems that require pumps, pipes or pipes to transport water, and radiators, often with fans, to resist heat to the atmosphere. Depending on the application, it can also present an additional element of risk; in computer applications, for example, the leaking of water from a tube or connection can quickly damage sensitive electronic components.
Water also accelerates corrosion of metal parts and is a good medium for biological growth. Minerals dissolved in the natural water supply are concentrated by evaporation to leave a so-called scale pile. Cooling water often requires the addition of chemicals to minimize corrosion and isolate heap scale and biofouling.
Water cooling also has a boiling point temperature of about 220-230 degrees F, lower than the boiling point of the engine, and the vehicle can become overheated.
Open method
The open water cooling system utilizes evaporative cooling, lowering the remaining water temperature (not evaporated). This method is common in early internal combustion engines, until a scale buildup is observed from the salts and minerals dissolved in the water. Modern open cooling systems continuously dispose of a small amount of recirculating water as a blowdown to remove dissolved solids at low enough concentrations to prevent the formation of the crust. Some open systems use cheap tap water, but this requires a higher blowdown rate than deionized water or distilled water. Pure water systems still require blowdown to eliminate the accumulation of byproducts from chemical treatments to prevent corrosion and biofouling.
Automotive use
Pressurization
Modern automotive cooling systems are slightly pressurized, often up to 15 psi (103 kPa). This increases the boiling point of the coolant and reduces evaporation.
Antifreeze
The use of water coolers carries the risk of damage from freezing. Automotive and many other engine cooling applications require the use of a mixture of water and antifreeze to reduce freezing to unseasonable temperatures. Antifreeze also inhibits corrosion of different metals and can increase the boiling point, allowing more water cooling temperatures. Its distinctive odor also tells the operator to cool the system leak and problems that will escape the attention in the water cooling system only. The heated coolant mixture can also be used to heat the air in the car using a heating core.
Other additives
Other less common chemical additives are products to reduce surface tension. This additive is intended to improve the efficiency of automotive cooling systems. Such products are used to improve cooling of poor or underperforming cooling systems or in racing where the weight of a larger cooling system can be a disadvantage.
Power and transmitter
Since about 1930, it generally uses a water cooler for a powerful transmitter tube. Because this device uses high operating voltage (about 10 kV), it takes the use of deionized water and must be carefully controlled. Modern solid-state transmitters can be built so that even high-power transmitters do not require water cooling. Water cooling is also sometimes used for HVDC valve thyristors, which also require the use of deionized water.
Computer usage
The cooling of hot computer components with various liquids has been used since at least as far as the development of Cray-2 in 1982, using Fluorinert. Through the 1990s, water cooling for home PCs gradually gained recognition among fans, but it began to become more common after the introduction of the AML Athlon processor running in mid 2000. In 2011, there were several component manufacturers and a water cooling kit, and some specialized computer retailers include a variety of water cooling settings for their high-performance systems.
Water cooling can be used to cool many computer components, especially CPU. Water cooling typically uses CPU water blocks, water pumps, and water-to-air heat exchangers. By transferring device heat to separate, widely-spaced heat exchangers and using larger low-speed fans, water cooling may allow for quieter operation, increased processor speed (overclocking), or balance of both. Less commonly, GPU, Northbridges, Southbridges, hard disk drives, memory, voltage regulatory module (VRM), and even the power supply can be water cooled.
The size of the radiator can vary: from 40mm dual fan (80mm) to 140 quad fan (560mm) and thickness from 30mm to 80mm
Water cooler for desktop computers, until the late 1990s, homemade. They are made of car radiators (or more commonly, car heater core), aquarium pumps and home-made water blocks, laboratory PVC grade and silicone tubes and various reservoirs (homemade plastic bottles, or built using acrylic or cylindrical sheets of acrylic , usually clean) and or T-Line. Recently more and more companies are producing compact water cooling components that are compact enough to fit into the computer case. This, and the tendency to CPU higher power dissipation, has greatly increased the popularity of water cooling.
Special overclockers sometimes use vapor compression refrigeration or thermoelectric cooling instead of the more common standard heat exchanger. The water cooling system in which water is cooled directly by the evaporator coil of the phase change system can cool the circulating coolant below ambient air temperature (not possible with a standard heat exchanger) and, as a result, generally provides superior cooling of the computer heat-generating component. The downside of phase-change or thermoelectric cooling is that it uses more electricity, and antifreeze should be added due to low temperatures. In addition, insulation, usually in the form of lags surrounding the water pipe and neoprene pads around the cooled component, should be used to prevent damage caused by condensation of water vapor from the air on cold surfaces. Public places to borrow the required phase transition system are household dehumidifiers or air conditioners.
An alternative cooling system, which allows components to cool under the ambient temperature, but which eliminates the requirements for antifreeze and leftover pipe, is placing a thermoelectric device (commonly referred to as 'Peltier junction' or 'pelt' after Jean Peltier, documenting its effect) between heat-generating components and water blocks. Since the only zone of sub-ambient temperature is now in the interface with the component that generates heat itself, isolation is only required in the local area. The disadvantage of such a system is the higher power dissipation.
To avoid damage from condensation around the Peltier intersection, the proper installation requires it to "be in pot" with silicone epoxy. Epoxy is applied around the edges of the device, preventing air from entering or leaving the interior.
Apple Power Mac G5 is the first major desktop computer to have a water cooler as standard (albeit only on the fastest model). Dell follows it by sending their XPS computer with liquid cooling, using thermoelectric cooling to help cool the liquid. Currently, the only Dell computer that offers liquid cooling is their Alienware desktop.
Liquid cooling treatment
Liquid cooling techniques are increasingly being used for thermal management of electronic components. This type of cooling is a solution to ensure the optimization of energy efficiency while minimizing noise and space requirements. Especially useful in supercomputer or Data Center as a quick and easy shelf maintenance. After the demolition of the rack, rapid loose coupling technology eliminates spills for operator safety and protects fluid integrity (no dirt on the circuit). The clutch is also able to be locked (Panel mounted?) To allow blind connections in areas that are difficult to access. It is important in electronic technology to analyze the connection system to ensure:
- Non-spill (clean break, flush face couplings)
- Compact and lightweight (materials in special aluminum alloys)
- Operator safety (disconnection without spillage)
- Quick-release clutch sized for optimal flow
- Connection and misalignment compensation systems during connection on rack system
- Excellent resistance to vibration and corrosion
- Designed to hold a large number of connections even on cooling circuits under residual pressure
Industrial use
Industrial cooling towers can use river water, coastal water (seawater), or well water as their fresh water cooling source. Mechanically induced cooling towers or large forced drafts in industrial plants continually distribute cooling water through heat exchangers and other equipment in which water absorbs heat. The heat is then rejected into the atmosphere by evaporation of some of the water in the cooling tower where the overflowing air is contacted with the flow of water circulation. The loss of water that evaporates into the exhausted air into the atmosphere is replaced by "make-up" of fresh river water or fresh cooling water. Since evaporation of pure water is replaced by make-up water containing carbonate and other dissolved salts, a portion of the circulating water is also continuously disposed of as "blowdown" water to prevent excessive buildup of salt in circulating water.
In very large rivers, but more often on beach and estuary sites, "direct cooled" systems are often used. These industrial plants do not use cooling and atmospheric towers as heat sinks, but place waste heat into rivers or beach water instead. OTC systems depend on good rivers or seawater supply for their cooling needs. Many facilities, especially power plants, use millions of gallons of water per day for cooling. The facility is built with an intake structure designed to pump in large volumes of water at high flow rates. This structure also tends to attract large numbers of fish and other aquatic organisms, which are killed or injured on the intake screen.
Warm water is returned directly to the aquatic environment, often at a significant temperature (for aquatic life) above ambient water. Thermal pollution of rivers, estuaries and coastal waters is a consideration when determining the location of the plant.
High-quality industrial water (produced by reverse osmosis) and drinking water are sometimes used in industrial plants that require high-purity water cooling.
A hospital in Sweden relies on cooling snow from melted water from to cool its data centers, medical equipment, and maintain a comfortable temperature environment.
Some nuclear reactors use heavy water as a coolant. Heavy water is used in nuclear reactors because it is a weaker neutron absorber. This allows the use of less enriched fuels. For primary cooling systems, normal water is preferably used through the use of heat exchangers, since heavy water is much more expensive. Reactors that use other materials for moderation (graphite) can also use normal water for cooling.
Use of ships
Water is the ideal cooling medium for ships as they are constantly surrounded by water that generally remains at low temperatures throughout the year. However this poses a new challenge because cooling systems that operate with seawater need to be made from materials suitable for the environment. Such heat exchangers need to be made from materials such as Cupronickel, Bronze or Titanium to protect them from erosion or corrosion. The speed should also be much more limited than the fresh water cooling system. If the speed is too low; Then sand and other sediments can block the tube. If the speed is too high then the tube can be eroded by the sediment in the water.
Environmental considerations
Water is a beneficial environment for many life forms. Cooling water can change the natural water environment and create a new environment. The flow characteristics of the recirculating cooling water system encourage colonization by sessile organisms to use food supply, oxygen and circulating nutrients. The volume of water lost during evaporative cooling can decrease the natural habitat for aquatic organisms. Water temperatures increase the modified aquatic habitat by increasing the rate of biochemical reactions and reducing the oxygen saturation capacity of the habitat. Increased temperatures initially support population shifts from those requiring high oxygen concentrations from cold water to those who enjoy the benefits of increased metabolic rate in warm water. The temperature can be high enough to support thermophilic populations.
Biofouling heat exchange surfaces can reduce the heat transfer rate of the cooling system; and cooling tower biofouling can alter the flow distribution to reduce evaporative cooling rates. Biofouling can also create a differential oxygen concentration that increases the rate of corrosion. Free and open recirculation systems are most vulnerable to biofouling. Biofouling can be inhibited by temporary habitat modification. Temperature differences may inhibit the formation of thermophilic populations in intermittently operated facilities; and a deliberate short-run temperature spike can periodically kill a less tolerant population. Biocides have been commonly used to control biofouling where sustainable facility operations are required.
Large OTC flow rates can paralyze slow-swimming organisms including fish and shrimp on display that protect small drill tubes from heat exchangers from clogging. High temperatures or turbulent pumps and shear can kill or disable smaller organisms that pass through a screen trapped with cooling water. In the US, the coolant water intake structure kills billions of fish and other organisms each year. A more agile aquatic predator that consumes a stricken organism on the screen; and warm water predators and eaters colonize the cooling water debit to feed on entrained organisms.
The produced metal tends to return to the ore via electrochemical corrosion reaction. Water can accelerate corrosion both as an electrical conductor and solvent for metal ions and oxygen. Corrosion reactions take place more quickly as temperatures increase. Engine preservation in the presence of hot water has been improved by the addition of chemicals including zinc, chromate and phosphate. The first two have toxicity problems; and the latter associated with eutrophication. Concentrations of biocide residues and corrosion inhibitors are a potential concern for OTC and blowdown of open recirculation systems. With the exception of machines with short design life, closed recirculation systems require periodic cooling or replacement water treatment which raises similar concerns about the final discharge of cooling water containing chemicals used with the assumption of environmental safety of a closed system.
- Industrial cooling water regulation
The US Clean Water Act requires the Environmental Protection Agency (EPA) to issue regulations on the industrial cooling water intake structure. The EPA issued final regulations for new facilities in 2001 (amended 2003), and for existing facilities by 2014.
Chemical cooling water
Water contains various amounts of impurities from contact with the atmosphere, soil, and containers. The cooling water treatment adds another chemical that strives to maintain a satisfactory heat exchange.
Solids
Total dissolved solids or TDS (sometimes called filtration residue) is measured as residual mass remaining when the measured volume of filtered water is evaporated. Salinity measures water density or changes in conductivity caused by dissolved matter. Probability of scale formation increases with increasing total soluble solids. The solids commonly associated with scale formation are calcium and magnesium carbonate and sulfate. The initial corrosion rate increases with salinity in response to an increase in electrical conductivity, but then decreases after reaching the peak because higher salinity levels decrease dissolved oxygen levels.
Hydrogen
Ionized water becomes hydronium (H 3 O ) anion and hydroxide (OH - ) anions. The ionized hydrogen concentration (as protonated water) is expressed as pH. The low pH value increases the corrosion rate while the high pH value encourages scale formation. Amphoterism is rare among metals used in water-cooling systems, but the level of aluminum corrosion increases with pH values ​​above 9. Corrosion corrosion can be severe in water systems with copper and aluminum components. Acids can be added to the cooling water system to prevent scale formation if pH decrease will compensate for increased salinity and dissolved solids.
Phosphorus and Chromium
Concentrations of polyphosphates or phosphonates with zinc and chromate or similar compounds have been retained in the cooling system to maintain a clean heat exchange surface so that gamma iron oxide films and zinc phosphate can inhibit corrosion by mutating anodic and cathodic reaction points. This increases salinity and total dissolved solids, and phosphorus compounds can provide important limiting nutrients for algal growth that contribute to the refrigeration system biofouling or natural water environment eutrophication that receives blowdown or OTC water. Chromate reduces biofouling in addition to effective corrosion inhibition, but residual toxicity in blowdown or OTC water has encouraged reduced chromate concentrations and the use of less flexible inhibitor corrosion. Blowdown also contains chromium washed from a cooling tower made of wood preserved with a crimped copper arsenate.
Oxygen
Some groundwater contains very little oxygen when pumped from the well, but most of the natural water supply includes dissolved oxygen. Corrosion increases with increasing oxygen concentration. Dissolved oxygen approaches the level of saturation in the cooling tower. Dissolved oxygen is desired in blowdown or OTC water that is returned to the natural aquatic environment.
Biocides
Chlorine may be added in the form of hypochlorite to reduce biofouling, but then reduced to chloride to minimize blowdown toxicity or OTC water is returned to the natural aquatic environment. Hypochlorite further damages the wood cooling tower because of the increased pH. Chlorinated phenols have been used as biocides or washed from preserved wood in cooling towers. Both hypochlorite and pentachlorophenol have reduced effectiveness at pH values ​​greater than 8. Non-oxidizing biocides may be more difficult to detoxify before the release of blowdown or OTC water into the natural aquatic environment.
See also
- Cooling pool
- Cooling lake water in
- Free cooler
- Full immersion cooling
- Hot pipe cooling
- Cooling hopper
- Oil cooler
- Peltier cooling
- Termosipon (passive heat exchange)
References
Bibliography
External links
- The Theory and Practice of the Cooling Tower
- Howstuffworks "How to Work a Liquid-cooled PC"
Source of the article : Wikipedia
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