Heating, ventilation, and air-conditioning systems and methods

A method of operating an HVAC system, the method comprising:

• condensing high-pressure refrigerant in a condenser of the HVAC system;
• reducing the pressure of the high-pressure refrigerant exiting the condenser to a low-pressure refrigerant;
• evaporating the low-pressure refrigerant in an evaporator of the HVAC system;
• separating the low-pressure refrigerant into a low-pressure liquid refrigerant and a low-pressure gaseous refrigerant in a separator of the HVAC system;
• combining the low-pressure liquid refrigerant from the separator and the low-pressure gaseous refrigerant from the separator into a refrigerant mixture using an adjustable three-way valve;
• compressing the refrigerant mixture with a compressor of the HVAC system;
• measuring a temperature of the refrigerant leaving the compressor with a temperature sensor;
• and
• controlling the adjustable three-way valve based on the temperature of the refrigerant leaving the compressor measured by the temperature sensor so that the mixture has a specified vapor quality to lower a temperature of the refrigerant entering the compressor as well as the temperature of the refrigerant leaving the compressor.

A heating, ventilation, and air-conditioning (“HVAC”) system for use with a refrigerant, the HVAC system comprising:

• a compressor operable to compress the refrigerant;
• a condenser positioned downstream of the compressor, the condenser operable to condense the refrigerant;
• a temperature sensor operable to measure a temperature of the refrigerant leaving the compressor;
• an adjustable three-way valve positioned downstream of the condenser and operable to separate the refrigerant into a first flow and a second flow;
• and
• an evaporator positioned downstream of the adjustable three-way valve, the evaporator operable to receive and vaporize the refrigerant from the first flow,
• wherein the second flow is bypassed from the evaporator, the vaporized refrigerant from the evaporator is combined with the second flow into a mixture, and the adjustable three-way valve is controllable based on the temperature of the refrigerant leaving the compressor measured by the temperature sensor such that the mixture has a specified vapor quality to lower a temperature of the refrigerant entering the compressor as well as the temperature of the refrigerant leaving the compressor.