Electronics cooling

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Electronics cooling encompasses thermal design, analysis and experimental characterization of electronic systems as a discrete discipline with the product creation process for an electronics product, or an electronics sub-system within a product (e.g. an engine control unit (ECU) for a car). On-line sources of information are available [1] and a number of books have been published on this topic. [2] [3] [4]

Computer cooling is a sub-topic. Heat sinks are devices that are used to extend the surface area of electronic components available for air cooling, helping to lower the components case temperature. Fans are used to increase the air flow.

Thermal design and analysis is performed using hand calculations or spreadsheets, based on design rules or heat transfer correlations. Computer-aided engineering tools such as computational fluid dynamics are also used.

Active electronics cooling

Regular Peltier cooling setup for electronics Regular Peltier cooling setup for PC.png
Regular Peltier cooling setup for electronics

Besides passive heat conduction, active cooling consuming electricity can be achieved through the thermoelectric coolers. [5]

When electrical voltage is added to an n-type (p-type) semiconductor material, the electric filed will drive electrons (holes) from one end to the other, which will also carry the electronic kinetic energy and entropy. A temperature gradient will be finally built up to balance the driven force of electrical field. This is called the Peltier effect, and the refrigeration or cooling device made based on this effect is called the Peltier cooler. One Peltier cooler is at least consisted of one n-leg and one p-leg, which is also called a Peltier junction. [6] Although, Peltier coolers are generally only around 10-15% as efficient as a reversed Carnot cycle, or as 40–60% efficient as a vapor-compression cycle, it may be the only choice for applications in some special scenarios, including electronics on satellites, in submarines, and at an extremely compact space, due to their solid state nature, low maintenance need, compact size and noise-free operation. [7]

Multiple Peltier junctions, taking care of each specific temperature window, can usually be stacked to further enhance the overall performance on electronics cooling. As active heat pumps which consume power, thermoelectric coolers can produce temperatures below ambient, which is impossible with passive heatsinks, radiator-cooled liquid cooling, or heatpipe HSFs. However, while pumping heat, a Peltier module will typically consume more electric power than the heat amount being pumped. [8]

Related Research Articles

<span class="mw-page-title-main">Heat engine</span> System that converts heat or thermal energy to mechanical work

In thermodynamics and engineering, a heat engine is a system that converts heat to usable energy, particularly mechanical energy, which can then be used to do mechanical work. While originally conceived in the context of mechanical energy, the concept of the heat engine has been applied to various other kinds of energy, particularly electrical, since at least the late 19th century. The heat engine does this by bringing a working substance from a higher state temperature to a lower state temperature. A heat source generates thermal energy that brings the working substance to the higher temperature state. The working substance generates work in the working body of the engine while transferring heat to the colder sink until it reaches a lower temperature state. During this process some of the thermal energy is converted into work by exploiting the properties of the working substance. The working substance can be any system with a non-zero heat capacity, but it usually is a gas or liquid. During this process, some heat is normally lost to the surroundings and is not converted to work. Also, some energy is unusable because of friction and drag.

<span class="mw-page-title-main">Refrigeration</span> Process of moving heat from one location to another in controlled conditions

Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one. Refrigeration is an artificial, or human-made, cooling method.

<span class="mw-page-title-main">Thermoelectric cooling</span> Electrically powered heat-transfer

Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC) and occasionally a thermoelectric battery. It can be used either for heating or for cooling, although in practice the main application is cooling. It can also be used as a temperature controller that either heats or cools.

<span class="mw-page-title-main">Heat sink</span> Passive heat exchanger that transfers the heat

A heat sink is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device's temperature. In computers, heat sinks are used to cool CPUs, GPUs, and some chipsets and RAM modules. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light-emitting diodes (LEDs), where the heat dissipation ability of the component itself is insufficient to moderate its temperature.

<span class="mw-page-title-main">Heat pipe</span> Heat-transfer device that employs phase transition

A heat pipe is a heat-transfer device that employs phase transition to transfer heat between two solid interfaces.

<span class="mw-page-title-main">Water cooling</span> Method of heat removal from components and industrial equipment

Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non-toxic; however, it can contain impurities and cause corrosion.

<span class="mw-page-title-main">Evaporative cooler</span> Device that cools air through the evaporation of water

An evaporative cooler is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning systems, which use vapor-compression or absorption refrigeration cycles. Evaporative cooling exploits the fact that water will absorb a relatively large amount of heat in order to evaporate. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evaporation). This can cool air using much less energy than refrigeration. In extremely dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of building occupants.

<span class="mw-page-title-main">Chiller</span> Machine that removes heat from a liquid coolant via vapor compression

A chiller is a machine that removes heat from a liquid coolant via a vapor-compression, adsorption refrigeration, or absorption refrigeration cycles. This liquid can then be circulated through a heat exchanger to cool equipment, or another process stream. As a necessary by-product, refrigeration creates waste heat that must be exhausted to ambience, or for greater efficiency, recovered for heating purposes. Vapor compression chillers may use any of a number of different types of compressors. Most common today are the hermetic scroll, semi-hermetic screw, or centrifugal compressors. The condensing side of the chiller can be either air or water cooled. Even when liquid cooled, the chiller is often cooled by an induced or forced draft cooling tower. Absorption and adsorption chillers require a heat source to function.

<span class="mw-page-title-main">Computer cooling</span> The process of removing waste heat from a computer

Computer cooling is required to remove the waste heat produced by computer components, to keep components within permissible operating temperature limits. Components that are susceptible to temporary malfunction or permanent failure if overheated include integrated circuits such as central processing units (CPUs), chipsets, graphics cards, and hard disk drives.

Active cooling is a heat-reducing mechanism that is typically implemented in electronic devices and indoor buildings to ensure proper heat transfer and circulation from within.

Cooling is removal of heat, usually resulting in a lower temperature and/or phase change. Temperature lowering achieved by any other means may also be called cooling. The transfer of thermal energy may occur via thermal radiation, heat conduction or convection. Examples can be as simple as reducing temperature of a coffee.

<span class="mw-page-title-main">Thermosiphon</span> Method of heat exchange in which convection drives pumpless circulation

Thermosiphon is a method of passive heat exchange, based on natural convection, which circulates a fluid without the necessity of a mechanical pump. Thermosiphoning is used for circulation of liquids and volatile gases in heating and cooling applications such as heat pumps, water heaters, boilers and furnaces. Thermosiphoning also occurs across air temperature gradients such as those utilized in a wood fire chimney or solar chimney.

<span class="mw-page-title-main">Thermal management (electronics)</span> Regulation of the temperature of electronic circuitry to prevent inefficiency or failure

All electronic devices and circuitry generate excess heat and thus require thermal management to improve reliability and prevent premature failure. The amount of heat output is equal to the power input, if there are no other energy interactions. There are several techniques for cooling including various styles of heat sinks, thermoelectric coolers, forced air systems and fans, heat pipes, and others. In cases of extreme low environmental temperatures, it may actually be necessary to heat the electronic components to achieve satisfactory operation.

<span class="mw-page-title-main">Vapor-compression refrigeration</span> Refrigeration process

Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS), in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air conditioning of buildings and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage of foods and meats, refrigerated trucks and railroad cars, and a host of other commercial and industrial services. Oil refineries, petrochemical and chemical processing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems. Cascade refrigeration systems may also be implemented using two compressors.

<span class="mw-page-title-main">Thermoelectric generator</span> Device that converts heat flux into electrical energy

A thermoelectric generator (TEG), also called a Seebeck generator, is a solid state device that converts heat flux directly into electrical energy through a phenomenon called the Seebeck effect. Thermoelectric generators function like heat engines, but are less bulky and have no moving parts. However, TEGs are typically more expensive and less efficient.

<span class="mw-page-title-main">Heat pump and refrigeration cycle</span> Mathematical models of heat pumps and refrigeration

Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. A heat pump is a mechanical system that allows for the transmission of heat from one location at a lower temperature to another location at a higher temperature. Thus a heat pump may be thought of as a "heater" if the objective is to warm the heat sink, or a "refrigerator" or “cooler” if the objective is to cool the heat source. In either case, the operating principles are similar. Heat is moved from a cold place to a warm place.

<span class="mw-page-title-main">Thermal management of high-power LEDs</span>

High power light-emitting diodes (LEDs) can use 350 milliwatts or more in a single LED. Most of the electricity in an LED becomes heat rather than light. If this heat is not removed, the LEDs run at high temperatures, which not only lowers their efficiency, but also makes the LED less reliable. Thus, thermal management of high power LEDs is a crucial area of research and development. It is necessary to limit both the junction and the phosphor particles temperatures to a value that will guarantee the desired LED lifetime.

<span class="mw-page-title-main">Thermal copper pillar bump</span>

The thermal copper pillar bump, also known as the "thermal bump", is a thermoelectric device made from thin-film thermoelectric material embedded in flip chip interconnects for use in electronics and optoelectronic packaging, including: flip chip packaging of CPU and GPU integrated circuits (chips), laser diodes, and semiconductor optical amplifiers (SOA). Unlike conventional solder bumps that provide an electrical path and a mechanical connection to the package, thermal bumps act as solid-state heat pumps and add thermal management functionality locally on the surface of a chip or to another electrical component. The diameter of a thermal bump is 238 μm and 60 μm high.

<span class="mw-page-title-main">Thermoelectric acclimatization</span>

Thermoelectric acclimatization depends on the possibility of a Peltier cell of absorbing heat on one side and rejecting heat on the other side. Consequently, it is possible to use them for heating on one side and cooling on the other and as a temperature control system.

<span class="mw-page-title-main">Cascade refrigeration</span> Refrigeration process used to achieve temperatures below -100 degrees Celsius without liquid gases

A cascade refrigeration cycle is a multi-stage thermodynamic cycle. An example two-stage process is shown at right. The cascade cycle is often employed for devices such as ULT freezers.

References

  1. Electronics Cooling Magazine
  2. Allan D. Kraus & Avram Bar-Cohen (1995), Design & Analysis of Heat Sinks, John Wiley & Sons, ISBN   0-471-01755-8
  3. Kordyban, Tony (1998). Hot Air Rises and Heat Sinks - Everything You Know About Cooling Electronics Is Wrong. ASME Press. ISBN   0-7918-0074-1.
  4. Remsburg, Ralph (2001). Thermal Design of Electronic Equipment. CRC Press. ISBN   0-8493-0082-7.
  5. Taylor, R.A.; Solbrekken, G.L. (2008). "Comprehensive system-level optimization of thermoelectric devices for electronic cooling applications". IEEE Transactions on Components and Packaging Technologies. 31: 23–31. doi:10.1109/TCAPT.2007.906333. S2CID   39137848.
  6. Goldsmid, H. Julian (2016). Introduction to Thermoelectricity. Springer Series in Materials Science. Vol. 121. Berlin, Heidelberg: Springer Berlin Heidelberg. Bibcode:2016inh..book.....G. doi:10.1007/978-3-662-49256-7. ISBN   978-3-662-49255-0.
  7. "The Prospects of Alternatives to Vapor Compression Technology for Space Cooling and Food Refrigeration Applications" (PDF). Archived (PDF) from the original on 6 March 2013. Retrieved 23 January 2013.
  8. "Technology | Incooling". www.incooling.com.