US 12,247,771 B2
Systems and methods for defrost of heat pump systems
Michael F. Taras, Spring, TX (US)
Assigned to Daikin Comfort Technologies Manufacturing, L.P., Waller, TX (US)
Filed by Daikin Comfort Technologies Manufacturing, L.P., Waller, TX (US)
Filed on Jul. 13, 2022, as Appl. No. 17/812,235.
Prior Publication US 2024/0019185 A1, Jan. 18, 2024
Int. Cl. F25B 47/02 (2006.01); F25B 41/26 (2021.01); F25B 49/02 (2006.01)
CPC F25B 47/025 (2013.01) [F25B 41/26 (2021.01); F25B 49/02 (2013.01); F25B 2347/02 (2013.01); F25B 2600/2507 (2013.01); F25B 2700/02 (2013.01); F25B 2700/2106 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A heating, ventilation, and air conditioning (HVAC) system operable to use a refrigerant to heat or cool an indoor space and comprising:
a compressor, an outdoor heat exchanger, an indoor heat exchanger, an expansion device, and a four-way valve connected together as a refrigerant circuit, wherein the four-way valve is operable to flow the refrigerant through the expansion device in a first direction in a cooling mode and in a second direction, opposite the first direction, in a heating mode; and
a defrost circuit connected to the refrigerant circuit and comprising a first three-way valve, a defrost line, a defrost passage in the outdoor heat exchanger, and a defrost return line;
wherein when the HVAC system is in a defrost mode:
the four-way valve is operable to direct the refrigerant flow in the second direction through the outdoor heat exchanger;
the first three-way valve is operable to divert some or all of the refrigerant from the refrigerant circuit and through the defrost circuit to defrost the outdoor heat exchanger; and
the defrost return line returns the diverted refrigerant to the refrigerant circuit upstream of the expansion device and downstream of the indoor heat exchanger with respect to the second direction.