Water cooling
Water cooling is a method of
Water cooling is commonly used for cooling automobile
Other uses include the cooling of lubricant oil in pumps; for cooling purposes in heat exchangers; for cooling buildings in HVAC and in chillers.
Mechanism
Advantages
Water is inexpensive,
Disadvantages
Water accelerates the corrosion of metal parts and is a favorable medium for biological growth. Dissolved minerals in natural water supplies are concentrated by evaporation to leave deposits called scale. Cooling water often requires the addition of chemicals to minimize corrosion and insulating deposits of scale and biofouling.[4]
Water contains varying amounts of impurities from contact with the atmosphere, soil, and containers. Being both an electrical conductor and a solvent for metal ions and oxygen, water can accelerate corrosion of machinery being cooled. Corrosion reactions proceed more rapidly as temperature increases.
Chlorine may be added in the form of hypochlorite to decrease biofouling in cooling water systems, but is later reduced to chloride to minimize the toxicity of blowdown or OTC water returned to natural aquatic environments. Hypochlorite is increasingly destructive to wooden cooling towers as pH increases. Chlorinated phenols have been used as biocides or leached from preserved wood in cooling towers. Both hypochlorite and pentachlorophenol have reduced effectiveness at pH values greater than 8.[14] Non-oxidizing biocides may be more difficult to detoxify prior to release of blowdown or OTC water to natural aquatic environments.[15]
Concentrations of polyphosphates or phosphonates with zinc and chromates or similar compounds have been maintained in cooling systems to keep heat exchange surfaces clean enough that a film of gamma iron oxide and zinc phosphate can inhibit corrosion by passivating anodic and cathodic reaction points.[16] These increase salinity and total dissolved solids, and phosphorus compounds may provide the limiting essential nutrient for algal growth contributing to biofouling of the cooling system or to eutrophication of natural aquatic environments receiving blowdown or OTC water. Chromates reduce biofouling in addition to effective corrosion inhibition in the cooling water system, but residual toxicity in blowdown or OTC water has encouraged lower chromate concentrations and the use of less-flexible corrosion inhibitors.[7] Blowdown may also contain chromium leached from cooling towers constructed of wood preserved with chromated copper arsenate.[17]
Some groundwater contains very little oxygen when pumped from wells, but most natural water supplies include dissolved oxygen. Increasing oxygen concentrations accelerate corrosion.[4] Dissolved oxygen approaches saturation levels in cooling towers. It is beneficial in blowdown or OTC water being returned to natural aquatic environments.[20]
Water ionizes into
Steam power stations
Few other cooling applications approach the large volumes of water required to condense low-pressure steam at power stations.[24] Many facilities, particularly electric power plants, use millions of gallons of water per day for cooling.[25] Water cooling on this scale may alter natural water environments and create new environments. Thermal pollution of rivers, estuaries and coastal waters is a consideration when siting such plants. Water returned to aquatic environments at temperatures higher than the ambient receiving water modifies aquatic habitat by increasing biochemical reaction rates and decreasing the oxygen saturation capacity of the habitat. Temperature increases initially favor a population shift from species requiring the high-oxygen concentration of cold water to those enjoying the advantages of increased metabolic rates in warm water.[11]
Once-through cooling (OTC) systems may be used on very large rivers or at
The U.S.
Cooling towers
As an alternative to OTC, industrial cooling towers may use recirculated river water, coastal water (seawater), or well water. Large mechanical induced-draft or forced-draft cooling towers in industrial plants continuously circulate cooling water through heat exchangers and other equipment where the water absorbs heat. That heat is then rejected to the atmosphere by the evaporation of some of the water in cooling towers where upflowing air contacts the downflowing water. The loss of evaporated water into the air exhausted to the atmosphere is replaced by "make-up" fresh river water or fresh cooling water, but the amount of water lost during evaporative cooling may affect the natural habitat for aquatic organisms. Because the evaporated pure water is replaced by make-up water containing carbonates and other dissolved salts, a portion of the circulating water is continuously discarded as "blowdown" water to minimize the excessive build-up of salts in the circulating water; these blowdown wastes may change the receiving water quality.[33]
Internal combustion engines
The heated coolant mixture can be used to warm the air inside the car by means of the heater core. Also, the water jacket around an engine is very effective at deadening mechanical noises, making the engine quieter.
Open method
An open water cooling system makes use of
Pressurization
Water for cooling has a boiling point temperature of around 100 degrees C at atmospheric pressure. Engines operating at higher temperatures may require a pressurized recycle loop to prevent overheating.[35] Modern automotive cooling systems often operate at 15 psi (103 kPa) to raise the boiling-point of the recycling water coolant and reduce evaporative losses.[36]
Antifreeze
The use of water cooling carries the risk of damage from freezing. Automotive and many other engine cooling applications require the use of a water and antifreeze mixture to lower the freezing point to a temperature unlikely to be experienced. Antifreeze also inhibits corrosion from dissimilar metals and can increase the boiling point, allowing a wider range of water cooling temperatures.[36] Its distinctive odor also alerts operators to cooling system leaks and problems that would go unnoticed in a water-only cooling system.
Other additives
Other less common chemical additives are products to reduce surface tension. These additives are meant to increase the efficiency of automotive cooling systems. Such products are used to enhance the cooling of underperforming or undersized cooling systems or in racing where the weight of a larger cooling system could be a disadvantage.[citation needed]
Power electronics and transmitters
Since approximately 1930 it is common to use water cooling for tubes of powerful transmitters. As these devices use high operation voltages (around 10 kV), the use of deionized water is required and it has to be carefully controlled. Modern solid-state transmitters can be built so that even high-power transmitters do not require water cooling. Water cooling is however also sometimes used for thyristors of HVDC valves, for which the use of deionized water is required.[citation needed]
Liquid cooling maintenance
Liquid cooling techniques are increasingly being used for the thermal management of electronic components. This type of cooling is a solution to ensure the optimisation of energy efficiency while simultaneously minimising noise and space requirements. Especially useful in supercomputers or Data Centers because maintenance of the racks is quick and easy. After disassembly of the rack, advanced-technology quick-release couplings eliminate spillage for the safety of operators and protect the integrity of fluids (no impurities in the circuits). These couplings are also capable of being locked (Panel mounted?) to allow blind connection in difficult-to-access areas.[citation needed] It is important in electronics technology to analyse the connection systems to ensure:
- Non-spill sealing (clean break, flush face couplings)
- Compact and lightweight (materials in special aluminum alloys)
- Operator safety (disconnection without spillage)
- Quick-release couplings sized for optimized flow
- Connection guiding system and compensation of misalignment during connection on rack systems
- Excellent resistance to vibration and corrosion
- Designed to withstand a large number of connections even on refrigerant circuits under residual pressure
Computer usage
Water cooling often adds complexity and cost in comparison to air cooling design by requiring a pump, tubing or piping to transport the water, and a radiator, often with fans, to reject the heat to the atmosphere. Depending on the application, water cooling may create an additional element of risk where leakage from the water coolant recycle loop can corrode or short-circuit sensitive electronic components.
The primary advantage of water cooling for cooling CPU cores in computing equipment is transporting heat away from the source to a secondary cooling surface to allow for large, more optimally designed radiators rather than small, relatively inefficient fins mounted directly on the heat source. Cooling hot computer components with various fluids has been in use since at least the Cray-2 in 1982, which used Fluorinert. Through the 1990s, water cooling for home PCs slowly gained recognition among enthusiasts, but it became noticeably more prevalent after the introduction of the first Gigahertz-clocked processors in the early 2000s. As of 2018, there are dozens of manufacturers of water cooling components and kits, and many computer manufacturers include preinstalled water cooling solutions for their high-performance systems.
Water cooling can be used for many computer components, but usually it is used for the
Internal radiator size may vary: from 40mm dual fan (80mm) to 140 quad fan (560mm) and thickness from 30mm to 80mm. Radiator fans may be mounted on one or both sides. External radiators can be much larger than their internal counterparts as they do not need to fit in the confines of a computer case. High-end cases may have two rubber grommeted ports in the back for the inlet and outlet hoses, which allow external radiators to be placed far away from the PC.
A T-Line is used to remove trapped air bubbles from the circulating water. It is made with a t-connector and a capped-off length of tubing. The tube n acts as a mini-reservoir and allows air bubbles to travel into it as they are caught into the "tee" connector, and ultimately removed from the system by bleeding. The capped line may be capped with a fill-port fitting to allow the release of trapped gas and the addition of liquid.[citation needed]
Water coolers for desktop computers were, until the end of the 1990s, homemade. They were made from car
Dedicated overclockers have occasionally used
An alternative cooling scheme, which also enables components to be cooled below the ambient temperature while obviating the requirement for antifreeze and lagged pipes, is to place a thermoelectric device (commonly referred to as a 'Peltier junction' or 'pelt' after Jean Peltier, who documented the effect) between the heat-generating component and the water block. Because the only sub-ambient temperature zone now is at the interface with the heat-generating component itself, insulation is required only in that localized area. The disadvantage of such a system is higher power dissipation.[citation needed]
To avoid damage from condensation around the Peltier junction, a proper installation requires it to be "potted" with silicone epoxy. The epoxy is applied around the edges of the device, preventing air from entering or leaving the interior.[citation needed]
Apple's Power Mac G5 was the first mainstream desktop computer to have water cooling as standard (although only on its fastest models). Dell followed suit by shipping their XPS computers with liquid cooling[citation needed], using thermoelectric cooling to help cool the liquid. Currently, Dell's only computers to offer liquid cooling are their Alienware desktops.[40]
Asus are the first and only mainstream brand to have put water-cooled laptops into mass production. Those laptops have a built-in air/water hybrid cooling system and can be docked to an external liquid cooling radiator for additional cooling and electrical power.[41][42]
Ships and boats
Water is an ideal cooling medium for vessels as they are constantly surrounded by water that generally remains at a low temperature throughout the year. Systems operating with seawater need to be manufactured from cupronickel, bronze, titanium or similarly corrosion-resistant materials. Water containing sediment may require velocity restrictions through piping to avoid erosion at high velocity or blockage by settling at low velocity.[43]
Other applications
Plant transpiration and animal perspiration use evaporative cooling to prevent high temperatures from causing unsustainable metabolic rates.
Machine guns used in fixed defensive positions sometimes use water cooling to extend barrel life through periods of rapid fire, but the weight of the water and pumping system significantly reduces the portability of water-cooled firearms. Water-cooled machine guns were extensively used by both sides during World War I; however, by the end of the war lighter weapons that rivaled the firepower, effectiveness and reliability of water-cooled models began to appear on the battlefield. Thus water-cooled weapons have played a far lesser role in subsequent conflicts.
A hospital in Sweden relies on snow-cooling from melt-water to cool its data centers, medical equipment, and maintain a comfortable ambient temperature.[44]
Some nuclear reactors use
High-grade industrial water (produced by reverse osmosis or distillation) and potable water are sometimes used in industrial plants requiring high-purity cooling water. Production of these high-purity waters creates waste byproduct brines containing the concentrated impurities from the source water.
In 2018, researchers from the University of Colorado Boulder and University of Wyoming invented a radiative cooling metamaterial known as "RadiCold", which has been developed since 2017. This metamaterial aids in cooling of water and increasing the efficiency of power generation, in which it would cool the underneath objects, by reflecting away the sun's rays while at the same time allowing the surface to discharge its heat as infrared thermal radiation.[45]
See also
- Cooling pond
- Deep lake water cooling
- Free cooling
- Full immersion cooling
- Heat pipe cooling
- Hopper cooling
- Oil cooling
- Peltiercooling
- Thermosiphon (passive heat exchange)
References
- ^ Kemmer (1979), pp. 1–1, 1–2.
- ^ Kemmer (1979), pp. 38–1, 38–4, 38-7 & 38-8.
- ^ King (1995), pp. 143, 439.
- ^ a b c d Betz, pp. 183–184.
- ^ Hemmasian-Ettefagh, Ali (2010). "Corrosion Inhibition of Carbon Steel in Cooling Water". Materials Performance. 49: 60–65.
- ISSN 0254-0584.
- ^ a b Kemmer (1979), pp. 38–20, 38–21.
- ^ Goldman & Horne (1983), pp. 153, 160.
- ^ Betz, p. 215.
- ^ Krosofsky, Andrew (18 January 2021). "How to Properly and Safely Dispose of Antifreeze". Green Matters. Retrieved 23 June 2021.
- ^ a b Reid (1961), pp. 267–268.
- .
- ^ Betz, p. 202.
- ^ Betz, pp. 203–209.
- ^ Veil, John A.; Rice, James K.; Raivel, Mary E.S. "Biocide Usage in Cooling Towers in the Electric Power and Petroleum Refining Industries" (PDF). United States Department of Energy. Retrieved 23 June 2021.
- ^ Betz, pp. 198–199.
- ^ "Leaching of CCA From Treated Wood". National Pesticide Information Center. Retrieved 23 June 2021.
- ^ Franson (1975), pp. 89–98.
- ^ Franson (1975), pp. 99–100.
- ^ "Dissolved Oxygen and water quality". State of Kentucky. Retrieved 23 June 2021.
- ^ Franson (1975), pp. 406–407.
- ^ Betz, pp. 191–194.
- ^ McGeehan, Patrick (12 May 2015). "Fire Prompts Renewed Calls to Close the Indian Point Nuclear Plant". New York Times.
- ^ U.S. Environmental Protection Agency (EPA). (1997). Profile of the Fossil Fuel Electric Power Generation Industry (Report). Washington, D.C. Document No. EPA/310-R-97-007. p. 79.
- ^ EPA (2010). "Partial List of Facilities Subject to Clean Water Act 316(b)."
- ^ a b EPA (2014). "Cooling Water Intakes."
- ^ Economic and Benefits Analysis for the Final Section 316(b) Phase II Existing Facilities Rule (PDF) (Report). EPA. 2004. EPA 821-R-04-005.
- ^ Technical Development Document for the Final Section 316(b) Existing Facilities Rule (PDF) (Report). EPA. May 2014. EPA 821-R-14-002.
- ^ Final Regulations to Establish Requirements for Cooling Water Intake Structures at Existing Facilities; Fact sheet (PDF) (Report). EPA. May 2014. EPA 821-F-14-001. Archived from the original (PDF) on 19 June 2020. Retrieved 23 November 2015.
- ^ United States. Clean Water Act, Section 316(b), 33 U.S.C. § 1316.
- ^ EPA. Cooling Water Intake Structures. Final rule: 2001-12-18, 66 FR 65255. Amended: 2003-06-19, 68 FR 36749.
- ^ EPA. "National Pollutant Discharge Elimination System—Final Regulations To Establish Requirements for Cooling Water Intake Structures at Existing Facilities and Amend Requirements at Phase I Facilities" Final rule. Federal Register, 79 FR 48300. 2014-08-15.
- LCCN 67019834. (See Chapter 2 for material balance relationships in a cooling tower)
- ^ Betz, p. 192.
- ^ Sturgess, Steve (August 2009). "Column: Keep Your Cool". Heavy Duty Trucking. Retrieved 2 April 2018.
- ^ a b Nice, Karim (22 November 2000). "How Car Cooling Systems Work". HowStuffWorks. HowStuffWorks, Inc. Retrieved 20 August 2012.
- ^ "Koolance 1300/1700W Liquid-Cooled Power Supply". Koolance.com. 22 March 2008. Retrieved 19 January 2018.
- ^ "Featured Projects – LiquidHaus". 6 May 2022. Archived from the original on 6 May 2022. Retrieved 6 May 2022.
- ^ "Dehumidifier & Air Conditioner". extremeoverclocking.com. 5 April 2011. Retrieved 11 March 2018.
- ^ "Alienware Desktops". Dell. Archived from the original on 28 July 2012. Retrieved 5 November 2009.
- ^ hermesauto (16 August 2016). "The Asus ROG GX800 is a water-cooled gaming laptop with two graphics chips". The Straits Times. Retrieved 7 May 2021.
- ^ "Asus ROG GX800VH Watercooled Laptop Review | KitGuru". Retrieved 7 May 2021.
- ^ Thermex "Heat Exchanger FAQ Page" 2016-12-12.
- ^ "Snow cooling in Sundsvall". www.lvn.se (in Swedish). Retrieved 20 August 2017.
- .
Bibliography
- Handbook of Industrial Water Conditioning (7th ed.). Betz Laboratories. 1976.
- Franson, Mary Ann (1975). Standard Methods for the Examination of Water and Wastewater (14th ed.). APHA, AWWA & WPCF. ISBN 0-87553-078-8.
- Goldman, Charles R.; Horne, Alexander J. (1983). Limnology. McGraw-Hill. ISBN 0-07-023651-8.
- Kemmer, Frank N. (1979). The NALCO Water Handbook. McGraw-Hill.
- King, James J. (1995). The Environmental Dictionary (3rd ed.). John Wiley & Sons. ISBN 0-471-11995-4.
- Reid, George K. (1961). Ecology in Inland Waters and Estuaries. Van Nostrand Reinhold.