Low-grade heat energy auxiliary-drive composite low-temperature refrigerating system

The invention discloses a low-grade heat energy auxiliary-drive composite low-temperature refrigerating system. The system comprises a generator, an ejector, a working medium pump, a condenser, a gas-liquid separator, a compressor, a first throttling component, a condensation evaporator, a second throttling component, an evaporator and a heater. A high-boiling-point component is condensed into liquid to serve as a low-boiling-point component cooling medium through the ejector driven by the low-grade heat energy; and the ejector has another function of increasing suction pressure of the low-boiling-point component at a suction port of the compressor to reduce the compression ratio of the compressor so as to realize lower refrigerating temperature. Because the compression process of the high-boiling-point component during circulation is finished by the ejector, the power consumption of the compressor is reduced; and the ejector also improves the suction pressure of the low-boiling-point component at the suction port of the compressor and is also favorable for further reducing the power consumption of the compressor. The system has the advantages of realizing high-efficiency utilization of a low-grade energy source, along with stable running, obvious energy saving effect and broad application prospect.