The low-temperature heat pump will have the following problems during actual use:
1. The heat is gradually attenuated as the ambient temperature decreases. As the ambient temperature drops, the suction pressure of the compressor decreases, and the specific volume of the suction
increases, resulting in a decrease in the volumetric efficiency of the compressor and the heating capacity per unit volume of the refrigerant. The heating capacity and heating coefficient (COP) of the
unit are correspondingly reduced. At this time, the amount of heat (room heat load) required by the user rises rapidly as the ambient temperature decreases.
2. Reliability of the compressor operating at low ambient temperatures. Under low ambient temperature, the system is prone to problems such as liquid return and high exhaust temperature, which
reduces the stability of the unit operation.
1. Increase the displacement of the compressor and the heat exchanger of the outdoor unit to increase the refrigerant flow rate and the heat absorption by evaporation, thereby increasing the heating capacity;
2. The two-stage compression intermediate air supply system is adopted to reduce the pressure ratio of each stage, and the intermediate air supply system injects part of the medium-pressure refrigerant into
the intermediate chamber of the two-stage compressor to increase the refrigerant flow rate, thereby increasing the system. Heat
3, using a cascade system, the system uses a medium-high temperature refrigerant combined with a low-temperature refrigerant, can reduce the pressure ratio and exhaust temperature of each stage, low ambient
temperature heating can be improved;
4. The three-stage compression intermediate air supply system is adopted to further reduce the pressure ratio and reduce the evaporator inlet dryness and increase the refrigerant circulation flow rate to increase
the system heating capacity on the basis of the two-stage compression air supply and increase enthalpy.
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