| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 97 === In general, the refrigeration system controls the temperature by turning on or turning off the fixed-frequency compressor, or installing the heating device, but these methods waste too much electricity.
The main method of controlling low temperature is using compressor system. Compressor system has a high energy efficiency and large refrigeration capacity in the general environment. However, when the evaporation temperature is lower, the efficiency of refrigeration device will decrease significantly. Therefore, we try to work this compressor system with other devices under the range of ultra-low temperature (-40 ℃ below) to maintain the low temperature.
In this study, we design a cascade system which is controlled by fuzzy, and operate the compressor system with Thermoelectric Cooler. We try to economize energy by" inputting different heat energy to change the speed of compressor." On the other hand, we also cool down the surface of the Thermoelectric Cooler by using of the cascade, and reducing the difference temperature of the hot and cold surface substantially. Therefore, it is cold enough to achieve the target output temperature, -40 ℃, in second times.
According to the simulation results, the speeds of the compressor are different with operating the cascade refrigeration system at 65 watts, 30 watts and 10 watts respectively, and the power consumption is also reduced with lower load. Finally, the water temperature remains at -40 ℃ stably with our investigation.
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