At the moment, we have not developed any cooling devices, primarily because it requires the development of different materials to those upon which we have chosen to focus for power generation applications. However, we know from laboratory tests in R&D materials (which unfortunately have no commercial use) that our approach can yield the same kind of performance uplift in cooling that we see in power generation. Given the array of potential cooling applications, some of which are detailed below, serving this area remains a long-term goal.
Refrigerators & Beverage Coolers
In recent years, standard thermoelectric cooling has been making inroads into the refrigeration market. These small units are frequently used in smaller spaces such as dormitory rooms, small apartments and hotel rooms, where the quiet operation is an added advantage. A camping/car type electric cooler can typically reduce the temperature by up to 20°C below ambient.
Of course, if MicroPower’s cooling efficiency can rival that of compressor-driven refrigerators, it would consequently enable the possibility of replacing that technology entirely, and fulfil the dream of mass market thermoelectric refrigeration that first gained traction in the 1960s (see Thermoelectrics Background).
Thermoelectric coolers can be miniaturized to help alleviate the heat problems associated with high density packaging. Under these conditions, material performance is important as well as interfacial materials with higher thermal conductivity. Some electronic equipment intended for military use is cooled using thermoelectric devices, due to their reliability and low weight.
Thermoelectric coolers are a common component in thermal cyclers, used for the synthesis of DNA, in photon detectors in astronomical telescopes, spectrometers, and upscale digital cameras to eliminate pixel noise which can cause speckled images. In all cases, greater cooling efficiency will enable longer operational time, or less weight.
Infrared imaging products are intended for military, law enforcement, homeland and industrial security applications, and in locations such as nuclear plants, oil refineries and pipelines, water treatment plants, port authorities and penitentiary facilities. Products provide video images using the infrared portion of the spectrum to allow viewing in darkness or through fog or smoke.
Image resolution quality improves if the focal plane arrays of the cameras are cooled to temperatures as low as liquid nitrogen temperature, which is approximately 77K (-321°F or -196°C). For handheld or portable operation, the cooling technology must be lightweight, small and energy efficient. MicroPower cooling devices, once developed, would be well placed to serve this need.
Advances in semiconductor technology, including shrinking feature size, increased transistor density, and faster circuit speeds, have led to overheating becoming one of the biggest issues for silicon chip manufacturers and companies integrating these chips into phones, laptops, etc. Indeed, microscale hot spots can significantly degrade performance and reliability.
The application of conventional thermal packaging technology to provide uniform chip cooling results in lower allowable chip power dissipation or overcooling of large areas of the chip. Consequently, the IT industry has shown considerable interest in making use of thermoelectric cooling devices that could selectively cool down the localized microscale hot spot.
The heat created in a PC or laptop must be dissipated in order to keep the various components within their safe operating temperatures. Currently, this is done using heat sinks to increase the surface area dissipating the heat, or fans, which speed up the exchange of air heated by computer parts for cooler ambient air.
The replacement of a computer cooling fan is very desirable in the mind of this industry due to reliability and power issues with the motor. A solid-state cooler fixed to the primary heat sources would be well received. MicroPower Modules could cool only the few main sources of heat on a computer printed wiring board. This could reduce the heat transfer problems so that convection and radiant cooling would suffice thereby eliminating the fan.
The use of thermoelectrics in vehicle seats to cool occupants is already a feature in upscale automobiles, with seat cushions designed to transfer heat away from the occupier’s body while cooling to the required temperature. Seat cooling technology also allows drivers to use their air conditioning system less frequently, thereby reducing gas usage, and the need for gases such as Freon.
These substances are believed to be extremely damaging to the atmosphere, and are considered to have hundreds of times the Global Warming Potential (GWP) of Carbon Dioxide. The spread of this technology through the automotive industry has been restricted largely due to cost, but we believe our technology could widen seat cooling to the mainstream.
Solid State Headlamp Cooling
The auto industry has been actively introducing high-intensity LEDs to replace incandescent and halogen head lamps since 2004. Their use reduces the weight of the lamp system and reduces energy consumption. However, LEDs actually produce a significant amount of heat per unit of light output which poses thermal management challenges for plastic headlamp housings.
In addition, this heat build-up materially reduces the light output of the emitters themselves. Keeping LED junction temperatures low at high power levels requires additional thermal management measures such as heat sinks and exhaust fans which can be quite expensive. A highly efficient MicroPower cooling device, as an active element of the lamp, could provide a desirable alternative.