Cryogenic stage mixed refrigerant suitable in two-stage cascade refrigeration system

Abstract

The invention relates to low temperature stage mixed refrigerant applicable to two-stage cascade refrigeration systems. The mixed refrigerant comprises ethane and monofluoro-methane, and is formed through physical mixture, wherein the molarity of ethane is 50 to 75 percent, and the balance is monofluoro-methane. The mixed refrigerant can also comprises ethane, monofluoro-methane and perfluoroethane, and is formed through physical mixture, wherein the molarity of ethane is 40 to 70 percent; the molarity of monofluoro-methane is 5 to 40 percent; the balance is perfluoroethane. The mixed refrigerant has high efficiency and high evaporation pressure, as well as good refrigeration capacity under the same compressor displacement, has zero ODP, greatly decreases GWP than R503 and R508B, and has good intersolubility with lubricating oil.

Description

Technical field [0001] The invention relates to a mixed refrigerant, in particular to a mixed refrigerant suitable for low-temperature stages in a two-stage cascade refrigeration system. Background technique [0002] Nowadays, the industry still uses a two-stage cascade refrigeration cycle to achieve a refrigeration temperature of about -80℃. The basic principle of cascade refrigeration is to use a high-temperature refrigeration system to cool a low-temperature refrigeration system to achieve a lower refrigeration temperature, in which each stage is a complete vapor compression cycle. Generally speaking, the evaporating temperature of high-temperature refrigeration systems is generally between -30°C and -40°C, while low-temperature refrigeration systems generally work between -60 and -80°C. [0003] The low-temperature refrigerant in the traditional cascade refrigeration system that can be applied to the temperature range of -80℃ is trifluorochloromethane (CClF) 3 Namely R13), tr...

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Problems solved by technology

But due to CO 2 Has a very high triple point temperature (-56.6°C), so the above-mentioned CO 2 The mixture used at low temperature is very easy to cause the system to fail to work properly due to the solid phase precipitation of carbon dioxide

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