Refrigeration systems with two-stage compression are used for the generation of particularly low temperatures. Therefore, two compressors are connected in series, with each compressor only having a relatively low pressure ratio. At very low temperatures large pressure differences are required between the evaporator and condenser. In a compressor the volumetric efficiency drops significantly at high pressure ratios. In addition, intercooling between the low pressure compressor and the high pressure compressor reduces the outlet temperature of the compressor to harmless values and improves the efficiency of the compression. This makes a more favourable dimensioning of the low pressure stage compressor possible. Due to the large specific volume it requires a larger capacity at lower drive power.
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