US 11,927,381 B2
Air-conditioning apparatus
Yusuke Tashiro, Tokyo (JP); Yasuhide Hayamaru, Tokyo (JP); Masakazu Kondo, Tokyo (JP); Masakazu Sato, Tokyo (JP); Naoki Nakagawa, Tokyo (JP); and Atsushi Kawashima, Tokyo (JP)
Assigned to Mitsubishi Electric Corporation, Tokyo (JP)
Appl. No. 16/961,005
Filed by Mitsubishi Electric Corporation, Tokyo (JP)
PCT Filed Jan. 26, 2018, PCT No. PCT/JP2018/002475
§ 371(c)(1), (2) Date Jul. 9, 2020,
PCT Pub. No. WO2019/146071, PCT Pub. Date Aug. 1, 2019.
Prior Publication US 2021/0080160 A1, Mar. 18, 2021
Int. Cl. F25B 5/02 (2006.01); F25B 41/20 (2021.01); F25B 47/02 (2006.01)
CPC F25B 5/02 (2013.01) [F25B 41/20 (2021.01); F25B 47/02 (2013.01); F25B 2300/00 (2013.01); F25B 2347/021 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An air-conditioning apparatus, comprising:
a compressor;
an indoor heat exchanger used as a condenser during a heating operation;
an outdoor heat exchanger including a lower heat exchanger and an upper heat exchanger stacked on top of the lower heat exchanger, the outdoor heat exchanger being used as an evaporator during the heating operation;
an outdoor fan configured to supply air to the outdoor heat exchanger;
a pressure reducing device provided downstream of the indoor heat exchanger in a direction in which refrigerant flows during the heating operation, the pressure reducing device being provided upstream of the outdoor heat exchanger in the direction in which refrigerant flows during the heating operation;
a switching device configured to switch a switching state to one of a first state and a second state, a discharge port of the compressor and an intake of the lower heat exchanger being connected to each other in the first state in which the lower heat exchanger receives heated refrigerant, the indoor heat exchanger is used as the condenser and the upper heat exchanger is used as the evaporator; the discharge port of the compressor and an intake of the upper heat exchanger being connected to each other in the second state in which the upper heat exchanger receives heated refrigerant, the indoor heat exchanger is used as the condenser and the lower heat exchanger is used as the evaporator; and
a controller configured to
control the switching state of the switching device,
perform a defrosting operation in which frost on the outdoor heat exchanger is caused to be melted, consisting of three defrosting controls, including
operate the outdoor fan,
initially, perform a first defrosting control for a first predetermined performance time for at least partial melting of frost on the lower heat exchanger, in which the switching state of the switching device is set to the first state,
responsive to finishing the first defrosting control, perform a second defrosting control for a second predetermined performance time for melting of frost on the upper heat exchanger to re-freeze on the lower heat exchanger, in which the switching state of the switching device is set to the second state,
responsive to finishing the second defrosting control, perform a third defrosting control for a third predetermined performance time for melting of frost and refrozen upper heat exchanger melt water on the lower heat exchanger, in which the switching state of the switching device is set to the first state, the first predetermined performance time is shorter than the third predetermined performance time, and
responsive to finishing the third defrosting control, restart the heating operation.