The invention discloses a variable-flow single-working medium
cascade refrigeration system with a common condenser and a common
evaporator. According to the invention, each
refrigeration compressor unit is composed of a
refrigeration compressor and four electromagnetic valves, wherein an exhaust end of the
refrigeration compressor is connected with the corresponding first
electromagnetic valve and the corresponding second
electromagnetic valve; a suction end of each
refrigeration compressor is connected with the corresponding third
electromagnetic valve and the corresponding fourth electromagnetic valve; the first electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with an inlet in the condenser; the second electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with a condensation side inlet in a condensation
evaporator; the third electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with an
evaporation side outlet in the condensation
evaporator; the fourth electromagnetic valves connected to the refrigeration compressors are connected in parallel and then are connected with an outlet in the evaporator; an outlet in the condenser is connected with an
evaporation side inlet in the condensation evaporator through a high temperature level
throttle valve; a condensation side outlet in the condensation evaporator is connected with an inlet in the evaporator through a low temperature level
throttle valve. The
cascade refrigeration
system of the invention is formed by single working medium, and does not contain an expansion container and other devices, so that the structure is simple.