Energy efficient heat pump with counterflow heat transfer arrangement

A heat pump for a heating, ventilation, and air conditioning (HVAC) system, comprising:

• a working fluid circuit;
• a compressor system configured to direct a working fluid along the working fluid circuit, wherein the compressor system comprises:
• a first compressor configured to direct the working fluid along a first portion of the working fluid circuit comprising a first expansion device to operate the heat pump in a cooling mode;
• and
• a second compressor configured to direct the working fluid along a second portion of the working fluid circuit comprising a second expansion device to operate the heat pump in a heating mode;
• a first heat exchanger disposed along the working fluid circuit, wherein the first compressor is configured to direct, during operation of the heat pump in the cooling mode, the working fluid through two or more passes of the first heat exchanger in a first sequential order to place the working fluid in a counterflow heat transfer arrangement with an air flow directed across the two or more passes of the first heat exchanger in a second sequential order opposite the first sequential order;
• a second heat exchanger disposed along the working fluid circuit;
• a third heat exchanger disposed along the working fluid circuit, wherein the third heat exchanger defines a first flow path configured to receive a first flow of the working fluid from the first heat exchanger and a second flow path configured to receive a second flow of the working fluid from the second heat exchanger, and the third heat exchanger is configured to place the first flow of the working fluid in a heat exchange relationship with the second flow of the working fluid in the heating mode and in the cooling mode;
• a first solenoid valve disposed along the working fluid circuit upstream of the first compressor relative to flow of the working fluid along the working fluid circuit, wherein the first solenoid valve is configured to control flow of the working fluid into the first compressor;
• a second solenoid valve disposed along the working fluid circuit upstream of the second compressor relative to flow of the working fluid along the working fluid circuit, wherein the second solenoid valve is configured to control flow of the working fluid into the second compressor;
• and
• a controller communicatively coupled to the first compressor, the second compressor, the first solenoid valve, and the second solenoid valve, wherein the controller is configured to:
• open the first solenoid valve, close the second solenoid valve, operate the first compressor, and suspend operation of the second compressor in the cooling mode;
• and
• open the second solenoid valve, close the first solenoid valve, operate the second compressor, and suspend operation of the first compressor in the heating mode.

A heat pump for a heating, ventilation, and air conditioning (HVAC) system, comprising:

• a working fluid circuit;
• a compressor system configured to direct a working fluid along the working fluid circuit, wherein the compressor system comprises:
• a first compressor configured to direct the working fluid along a first portion of the working fluid circuit comprising a first expansion device to operate the heat pump in a cooling mode;
• and
• a second compressor configured to direct the working fluid along a second portion of the working fluid circuit comprising a second expansion device to operate the heat pump in a heating mode;
• a first heat exchanger disposed along the working fluid circuit, wherein the first compressor is configured to direct, during operation of the heat pump in the cooling mode, the working fluid through two or more passes of the first heat exchanger in a first sequential order to place the working fluid in a counterflow heat transfer arrangement with an air flow directed across the two or more passes of the first heat exchanger in a second sequential order opposite the first sequential order;
• a second heat exchanger disposed along the working fluid circuit;
• a suction conduit extending between the first heat exchanger and a suction side of the first compressor, wherein the suction conduit is configured to direct flow of the working fluid from the first heat exchanger toward the first compressor in the cooling mode;
• a third heat exchanger disposed along the working fluid circuit, wherein the third heat exchanger defines a first flow path and a second flow path, the working fluid circuit comprises an additional conduit extending from the suction conduit to the second compressor, the first flow path is disposed along the suction conduit, the second flow path is disposed along the additional conduit, and the third heat exchanger is configured to place a first flow of the working fluid directed along the suction conduit in a heat exchange relationship with a second flow of the working fluid directed along the additional conduit;
• a first solenoid valve disposed along the working fluid circuit upstream of the first compressor relative to flow of the working fluid along the working fluid circuit, wherein the first solenoid valve is configured to control flow of the working fluid into the first compressor;
• a second solenoid valve disposed along the working fluid circuit upstream of the second compressor relative to flow of the working fluid along the working fluid circuit, wherein the second solenoid valve is configured to control flow of the working fluid into the second compressor;
• and
• a controller communicatively coupled to the first compressor, the second compressor, the first solenoid valve, and the second solenoid valve, wherein the controller is configured to:
• open the first solenoid valve, close the second solenoid valve, operate the first compressor, and suspend operation of the second compressor in the cooling mode;
• and
• open the second solenoid valve, close the first solenoid valve, operate the second compressor, and suspend operation of the first compressor in the heating mode.