What problems have been solved by an ultra-low temperature air source heat pump based on a single two-stage compressor?

The utility model relates to an ultra-low temperature air source heat pump based on a single-machine two-stage compressor, which belongs to the technical field of air source heat pump, the utility model comprises a Shell and tube heat exchanger, a liquid reservoir, a gas-liquid separator, a group of fin heat exchangers, a single-machine two-stage compressor, a horizontal oil separator, an oil cooler, an economizer, a pressure maintenance valve, a four-way reversing valve, a one-way valve, a plurality of solenoid valves, a plurality of expansion valves and a connecting pipeline. The utility model uses a single-machine two-stage compressor and an economizer to cool the superheated refrigerant discharged from the first-stage compressor to a nearly saturated gas state, and then enters the second-stage compressor to compress, thereby reducing the power consumption of the compressor under the condition of large pressure ratio, capable of stable heating at ultra-low temperatures. The air source heat pump can be used in a wide range of ambient temperature, which solves the problem that the air source heat pump can not be used in the cold area because of its high power consumption and poor heating effect.