Abstract: An indirect evaporative cooling system includes a frame, a heat exchanger core, a supply fan to move indoor return air inside the heat exchanger core, an exhaust fan to move air over the heat exchanger core in a direction perpendicular to the indoor return air, a water collection and management system disposed within the frame below the heat exchanger core to collect water sprayed onto the heat exchanger core, and a water spray system positioned above the heat exchanger core to supply water that is evenly distributed to a top surface of the heat exchanger core. The water spray system includes at least one water spray assembly having an enclosure with a surface, and at least two spray nozzles configured to spray water on a portion of the top surface of the heat exchanger core. Each spray nozzle is configured to produce a flat, fan-shaped spray pattern.

Abstract: An indirect evaporative cooling system includes a frame, a heat exchanger core, a supply fan to move indoor return air inside the heat exchanger core, and an outdoor exhaust fan supported by the frame to draw outdoor air over the heat exchanger core in a direction perpendicular to the indoor return air. The system further includes a water spray system positioned above the heat exchanger core to spray water over the heat exchanger core, and a water collection and management system disposed below the heat exchanger core to collect water sprayed onto the heat exchanger core. The water collection and management system includes a water basin configured to contain fluid. The water basin is configured to include an operational water volume and a water reserve volume which together define a total usable water volume, and includes a water height set point to define the water reserve volume.

Abstract: An indirect evaporative cooling system includes a frame, a heat exchanger core, a supply fan to move indoor return air inside the heat exchanger core, and an outdoor exhaust fan supported by the frame to draw outdoor air over the heat exchanger core in a direction perpendicular to the indoor return air. The system further includes a water spray system positioned above the heat exchanger core to spray water over the heat exchanger core, and a water collection and management system disposed below the heat exchanger core to collect water sprayed onto the heat exchanger core. The water collection and management system includes a water basin configured to contain fluid. The water basin is configured to include an operational water volume and a water reserve volume which together define a total usable water volume, and includes a water height set point to define the water reserve volume.

Abstract: An indirect evaporative cooling system includes a frame, a heat exchanger core, a supply fan to move indoor return air inside the heat exchanger core, an exhaust fan to move air over the heat exchanger core in a direction perpendicular to the indoor return air, a water collection and management system disposed within the frame below the heat exchanger core to collect water sprayed onto the heat exchanger core, and a water spray system positioned above the heat exchanger core to supply water that is evenly distributed to a top surface of the heat exchanger core. The water spray system includes at least one water spray assembly having an enclosure with a surface, and at least two spray nozzles configured to spray water on a portion of the top surface of the heat exchanger core. Each spray nozzle is configured to produce a flat, fan-shaped spray pattern.

Abstract: Heat pumps with improved defrost cycles, methods of defrosting heat exchangers, and methods of improving the effectiveness of defrost cycles of heat pumps, for example, having a microchannel outdoor heat exchanger. A defrost valve in a refrigerant conduit opens during a defrost cycle to deliver hot refrigerant gas to a portion of the heat exchanger that otherwise defrosts more slowly or less completely than other portions of the heat exchanger. Particular embodiments pass hot refrigerant gas through a header of the heat exchanger, such as a bottom header. In a number of embodiments, the defrost valve is open only during a portion of the defrost cycle. Further, in some embodiments, the fan that is used to blow air through the heat exchanger is operated in a reversed direction during at least part of the defrost cycle to counteract natural convection through the heat exchanger.