PaxIT licenses fan technologies developed by PAX Scientific, Inc. to the information technology (IT) market.
PaxIT has been granted a master license to cooling technologies developed by PAX Scientific for application in the IT sector. Fans made using PAX Scientific technology are quieter and use less energy per flow unit than competitive products. PAX fans produce these benefits by reducing the amount of turbulence in the air before and after contact with the fan. The curved blades generate a laminar vortical flow on their downstream side, moving air centripetally and with markedly reduced turbulence.
A PaxIT license enables the licensee to use PAX design geometries for rotors and blades, and provides know-how for developing and manufacturing such products.
The world is completely dependent on information technology to operate and maintain its systems of telecommunications, government, commerce, the military, academia, and global finance. Trillions of data exchanges happen on a daily basis making reliable data storage, retrieval, and manipulation critical to system performance. Data density in terms of transistors per square inch doubles every 18 months and is expected to continue to do so for at least two more decades. Doubling circuit density increases the heat produced by integrated circuits. On average, heat has been increasing 17 percent annually. The more power a microprocessor draws, the hotter it becomes. The higher the temperature, the greater the risk of failure or clocking down. As the microprocessor industry literally heats up, it requires equal emphasis on technologies to cool electronic circuits. Moore’s Law has run into the Heat Wall. This is PaxIT’s business.
While improved chassis and chipset cooling is critical to computer and chip manufacturers in order to improve performance and remain competitive, the need for quieter PCs is becoming a product differentiator due to consumer demand and regulation. Voluntary and government mandates in Japan, Germany, and Sweden now require acoustic standards that lower PC noise emissions. While companies are striving to meet these more stringent standards, microprocessors continue to become more powerful, generating more heat. The additional heat fluxes require greater cooling, which can generate more noise.
About
Electronic Cooling Fans
Thermal
Management
Acoustic Management
Benefits of
Pax Fans
Cooling fans are a critical component of electronic equipment. A desktop computer can have three, four, even five fans: one to cool the CPU, a second fan to cool a chipset, one or two to cool the power supply, and one or two fans for the chassis. High performance video cards have their own processor fan, and with the increasing popularity of the faster 7,200-RPM hard drives, interior temperature management now employs thermo-controlled fans in an attempt to balance noise and temperature.
When personal computers were first introduced, fan noise was almost an assuring sound. It gave the user a sense that something was happening, becoming the auditory bridge from a mechanical to a virtual world. Paradoxically, early computers required very little cooling. Their power supply was 30-40 watts, and hard drives’ storage capacities were smaller than today’s RAMs. Current desktop computers often have multiple hard drives, a CD-ROM/CD-R/CD-RW/DVD units, a sound card, a graphics card, 512 MB RAM, even dual 1+ GHz processors, and a power supply requiring 400 watts or more. The amount of heat generated by one of today’s desktop PCs can warm a room in the winter and poses serious cooling challenges for engineers.
Modern electronic systems contain numerous components and sub-assemblies including circuit boards, fans, vents, baffles, porous plates such as electromagnetic shields, filters, cabling, power supplies, disk drives, heat sinks, and more. In IT systems, the goal of thermal management is to ensure that all components in a system are maintained within functional heat limits, a temperature range within which electrical circuits meet their performance criteria. Advanced thermal modeling techniques allow designers to predict air movement and temperature distribution in and around desktops, laptops, and servers. As with any system, there are various feedback loops, positive and negative, that compound the difficulties of designing computers, conflicts that invariably lead to compromises involving cost, time, assembly, noise, time to market, and performance.
The increased heat in modern computers is not only coming from more powerful microprocessors. Other heat sources include memory, system chip sets, graphics controllers, power components, capacitors, and disk drives. Even some of the smaller integrated circuits in plastic packages, once adequately cooled by normal air movement, are becoming denser, drawing more power and generating more heat. Part of the problem is that for some high-frequency processor signals, electromagnetic compatibility (EMC) regulations call for an enclosure, limiting cool air to hot devices. Because EMC regulations are a requirement, and thermal management solutions are not, innovative cooling solutions are needed by the industry. Many innovations including spray cooling and thermoelectric coolers are too expensive for manufacturers.
Heat sinks use a mass of thermally conductive material such as aluminum to move heat away from the microprocessor into the airstream where it can be carried away. Heat sinks draw and spread the heat upward through fins and folds, vertical ridges or columns, which allow heat to be conducted in three dimensions. Generally speaking, heat sinks cannot dissipate sufficient heat passively from microprocessors and must be accompanied by a fan making active heat sinks nearly ubiquitous in personal computers.
Increased airflow from fans significantly lowers the temperature of heat sinks and other components, and no modern IT system functions without them. Tests show that more heat is dissipated when a fan blows cool outside air into a PC rather than sucking warm air out. Regardless of an in- or outflow, the amount of heat a fan dissipates depends on the volume of air the fan moves.
To control both heat and noise, axial fans have evolved from simple devices spinning at a fixed rate to fans with an embedded thermal sensor that will vary the speed as required by operating conditions. The thermal control method contains a series of embedded thermal sensors connected to responsive thermal control circuits (TCC) that vary fan speed and cooling flow on all fans in the chassis. Although the TCC acts as a governor and safety valve, when it is on it decreases processor performance. Another method is a thermistor-based control system that measures external air entering the fan as a means to adjust fan speed. Fan speeds under thermistor regimens remain constant to approximately 27ºC and rise in a straight-line projection to approximately twice the rotational speed at 40ºC.
With the use of a TCC, fan speed increases as temperature rises, and conversely, as temperature falls, fan speed decreases. TCC parameters are set so that the rise of temperature does not exceed established functional limits. This is done from a cool state by letting fan speed idle or run at minimum levels until temperature approaches TMIN. Once TMIN is reached the fan switches to a minimum duty cycle, and its speed increases with the rise in processor temperatures until it reaches 100 percent flow capacity at TMIN + TRANGE. Because microprocessors are factory calibrated and specific computing systems have different heat sinks, fans, chassis, vents, airflows, geometry, ambient temperature environments, and heat generation, it is not possible to calculate TMIN and TRANGE for every computing system. Even with the same chassis and components, systems cannot be equilibrated because there can be variations in processor variability, altitude and other factors. If TMIN is set too low, excess noise is generated. If TMIN is set too high, performance will be degraded. To counter this, Intel uses the ADM 1027 dBCOOL controller, which monitors and constantly recalibrates temperature gradients. It simultaneously allows the computer to run as “hot” as possible, while creating the quietest system possible. Fujitsu Siemens Computers, the largest computer hardware company in Europe has a similar system of heat and noise control. Its patented system employs a fully integrated circuit, developed with STMicroelectronics NMB-Minebea, which accomplishes the same task as the ADM 1027 controller.
The Cause of Noise
Cooling fans are the chief source of noise problems associated with electronic equipment. Three years ago, listing a PC cooling fan's noise levels in product specification documents was almost unheard of. Today, it is common. Soon, it will be mandatory.
There is a wide spectrum of noise associated with axial fans. One source arises from fluctuation of the aerodynamic forces on the fan blade; a second is caused by turbulent flow in the blade wakes. Further, computers are not always designed to manage airflow and convection, other than meeting minimum OEM requirements. When additional components are installed into existing computers, the original cooling configuration is often stressed. In addition, high performance hard drivea not only generate their own noise, but also additional heat, requiring a separate cooling fan. When you add all of these factors to the need to cool the overall chassis with single or dual fans, you compound the acoustic problem. Although newer fans have modified blade configurations and housings-and better bearings or noiseless sleeve bearings that eliminate most oscillatory noise-the fan shape and speed still generate friction, backpressure, and secondary air oscillation, and therefore acoustic pollution.
Noise emissions are not limited to PCs. Current fan technologies found in internal cooling units of copy machines, projectors, graphics cards, fax machines, servers, storage devices, and printers all emit unacceptable levels of sound. Because competition, standards, and consumers are demanding change, manufacturers increasingly consider noise reduction as a production standard.
The Effect
Scientists know through research that high-intensity noise emissions
exposures, whether white noise or narrow band, are detrimental to human beings.
Intrusive noise levels emitted from PCs and other hardware cooling fans
reduce productivity and increase fatigue. Although such noise has been
accepted in moderate levels, a recent study published in the Journal of
Applied Psychology (Vol. 85, NO. 5, pp. 779-783, Oct. 2000) entitled Stress
and Open Office Noise demonstrates that such acceptance is inadvisable.
What is considered ambient or moderate noise can raise epinephrine levels leading to heart disease and other health issues. Excess sound reduces learning ability in children, and presumably adults as well. Acoustic pollution lowers the signal-to-noise ratio in the brain, sabotaging the benefit that IT is supposed to increase. As computers become integral to the educational environment, noise levels will become a more important factor determining which computer and peripheral brands are purchased and deployed.
PaxIT fans deliver higher flows, produce less noise, and use less energy. The geometrically curved blades generate a powerful vortex on their downstream sides, accelerating air towards the center (centripetally) with markedly reduced turbulence compared to all other fans. PaxIT fans “entrain” the air coming into the fan, creating a vortical flow in advance, decreasing threshold turbulence.
Some benefits include:
PaxIT blades can be manufactured of the same materials used to produce existing blades.
PaxIT blades can snap onto existing hubs and housings.
PaxIT fans can be adapted to all existing applications of fans in the IT world, whether they are DC axial, AC axial, diagonal, thermistor-controlled, or variable speed.
PaxIT fans can reduce energy use thus increasing battery life in laptops and notebooks.
PaxIT fans can deliver its benefits in energy and cooling performance with no additional manufacturing costs.
PaxIT technology can also be applied to heat sinks, chassis configurations, heat pipes, and heat spreaders.
