ASSOCIATED ENVIRONMENTAL Temperature Environmental Test Chambers

ASSOCIATED ENVIRONMENTAL Temperature Environmental Test Chambers

Temperature change is one of the most common stresses applied to a device. Temperature cycling is the process in which a device is subjected to multiple cycles of changing temperatures between specified extremes at relatively high rates of change fatiguing and causing inferior products to fail. It provides an excellent way to determine failure and analyze reliability of a device. Cycling will show at what temperature, both high and low, an item will cease to function properly. Most manufacturers have a standard high temperature range from +177°C to +170°C for reach-in chambers and welded walk-ins; however, it is possible for higher temperatures to be achieved with special construction and materials. To achieve low temperatures, manufacturers offer various refrigeration options for Temperature Chambers. Liquid Nitrogen (LN2) is one popular refrigerant that allows temperatures to be as low as -184°C. Carbon Dioxide (CO2) is another popular refrigerant however it can only achieve a low temperature of -68°C. A final option for Temperature Chambers is mechanical refrigeration. Mechanical refrigeration uses compressors to lower the temperature of the chamber and is available in a couple of configurations: single stage and cascade. Single State Temperature Chambers uses only one compressor and is able to bring the temperature down to -40°C. Cascade Temperature Chambers use two compressors in order to bring the chamber temperature down to -73°C or lower. A cascade refrigeration system consists of two separate systems. The low-stage provides cooling to the temperature chamber interior through a finned evaporator coil, which is positioned in the air plenum. The high-stage provides cooling to the cascade condenser. The cascade condenser is a heat exchanger that has one circuit which is the evaporator of the high-stage, and another circuit which is the condenser of the