Thermoelectric air conditioner - Products

Railway Age, March, 2002

Wireless telecommunication system electronic components must remain free of moisture, conductive dust, and heat--major causes of equipment failures, especially in subway operations, due to the presence of conductive airborne particulates created by braking systems. Even when communication rooms are equipped with standard air conditioner units, constant filter replacement is overwhelming. Enclosing electronic components can subject them to heat buildup. Simple ventilation systems are usually not enough to keep the operating environment at a suitable temperature. SEPTA solved these problems by working with Electro-grafics International Corp. to develop thermoelectric (solid state) air conditioners in a NEMA-style enclosure designed to maintain a barrier between the electronic components and the ambient environment. These devices maintain the operating environment at a level suitable for virtually maintenance free operation. They rely on the Peltier cooling effect, which, until the recent development of semicond uctor thermocouple materials, was a laboratory oddity. With these materials available, thermoelectric air conditioning is practical and efficient. Thermoelectric air conditioners have only one moving part (the fan) and are virtually maintenance free. They have features important to rail transit: insensitivity to vibration and shock, the ability to operate at ambient temperatures approaching 150 degrees F., and insensitivity to fluctuating input voltage. In contrast, compressor-driven units need a liquid coolant and are more sensitive to vibration and shock, fluctuating voltage, and temperatures above 125 degrees F.

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