A heat exchanger includes: a plurality of flat tubes each of which has a refrigerant flow passage through which refrigerant flows in an up-down direction, the plurality of flat tubes being arranged parallel to each other at intervals; a plurality of fins each of which is provided between adjacent flat tubes of the plurality of flat tubes; an upper header to which an upper end portion of each of the plurality of flat tubes is connected; and a lower header to which an a lower end portion of each of the plurality of flat tubes is connected. Lower end portions of the plurality of fins are not joined to the lower header, and a lower gap is formed between the lower end portions of the plurality of fins and the lower header.

A cooling system includes a heat exchanger having one or more rows of multiple flat tubes, louvered fins disposed between pairs of flat tubes, and special header tube connections to form a counter flow heat exchanger. Heat exchangers having multiple rows may be placed near or close to the server racks and may be in fluid communication with an outdoor heat exchanger having one or more rows. A single-phase fluid is pumped through a fluid circuit or loop, which includes the heat exchangers at the server racks and the outdoor heat exchanger. The single-phase fluid circuit including the heat exchangers at the IT racks may alternatively be in thermal communication with a water circuit that includes an outdoor fluid cooler. The flat tubes can be formed tubes with one or more channels, or extruded tubes with multiple channels. The heat exchangers include header tubes/connections, which facilitate easy fabrication and connection between rows and inlet/outlet, and lower the pressure drop.

A cooling system includes a heat exchanger having one or more rows of multiple flat tubes, louvered fins disposed between pairs of flat tubes, and special header tube connections to form a counter flow heat exchanger. Heat exchangers having multiple rows may be placed near or close to the server racks and may be in fluid communication with an outdoor heat exchanger having one or more rows. A single-phase fluid is pumped through a fluid circuit or loop, which includes the heat exchangers at the server racks and the outdoor heat exchanger. The single-phase fluid circuit including the heat exchangers at the IT racks may alternatively be in thermal communication with a water circuit that includes an outdoor fluid cooler. The flat tubes can be formed tubes with one or more channels, or extruded tubes with multiple channels. The heat exchangers include header tubes/connections, which facilitate easy fabrication and connection between rows and inlet/outlet, and lower the pressure drop.

A heat exchanger includes a plurality of first members, and a plurality of second members located between adjacent first members of the plurality of first members. The plurality of first members each include a plurality of openings and a first flow path connected to the plurality of openings. The plurality of second members each include a second flow path connected to the openings of the adjacent first members. The plurality of openings and the first flow path of the first member, and the second flow path of the second member define a flow path for a first fluid. A region between the adjacent first members defines a flow path for a second fluid. The heat exchanger further includes a third member extending toward the region on the first member.

A heat exchanger includes a plurality of first members, and a plurality of second members located between adjacent first members of the plurality of first members. The plurality of first members each include a plurality of openings and a first flow path connected to the plurality of openings. The plurality of second members each include a second flow path connected to the openings of the adjacent first members. The plurality of openings and the first flow path of the first member, and the second flow path of the second member define a flow path for a first fluid. A region between the adjacent first members defines a flow path for a second fluid. The heat exchanger further includes a third member extending toward the region on the first member.

A heat exchanger includes tubes arranged side by side, and a tank connected to ends of the tubes. The heat exchanger performs heat exchange between a first fluid flowing inside the tubes and a second fluid flowing outside the tubes. The heat exchanger includes a closing member disposed inside the tank and partially closing an opening provided at an end of a predetermined tube that is at least one of the tubes. The predetermined tube has a protrusion formed at the end of the predetermined tube. The closing member has an avoiding structure that avoids interference between the protrusion and the closing member.

A liquid to refrigerant heat exchanger includes an enclosed coolant volume that is at least partially defined by a plastic housing and by a metal closure plate. The metal closure plate can be part of a brazed assembly containing a continuous refrigerant flow path. The refrigerant flow path is disposed within the coolant volume, where heat can be transferred between the refrigerant within the refrigerant flow path and the liquid within the coolant volume. The plastic housing can at least partially surround the refrigerant flow path to at least partially bound a liquid flow path along a portion of the coolant volume. An inlet diffuser and an outlet diffuser can be mounted to the housing to direct the liquid through the housing. The plastic housing is sealingly joined to the closure plate along an outer periphery of the closure plate.

In one instance, a multistage microchannel condenser is provided for use as an aspect of a heating, ventilating, and air conditioning (HVAC) system. The multistage microchannel condenser includes at least two pluralities of flat tubes having microchannels, each associated with a different refrigeration circuit, that are interspersed so that when only one refrigeration circuit is operational, the multistage microchannel condenser still does not have any substantial thermal dead spots. Manifolds are used on each end of the multistage microchannel condenser to fluidly couple members of the at least two pluralities of flat tubes such that the refrigerant in each refrigeration circuit remains separated while still using a majority of the area of the face of the multistage microchannel condenser. Other aspects are presented.

A heat exchanger includes a frame and a plurality of coil passes disposed within the frame. The plurality of coil passes is configured to direct a flow of a refrigerant therethrough to transfer heat with an air flow passing over the heat exchanger. The plurality of coil passes include a U-bend disposed between first and second linear portions of the plurality of coil passes to redirect the refrigerant from a first longitudinal end of the heat exchanger to a second longitudinal end of the heat exchanger. Additionally, a first plurality of fins is disposed on an outer surface the U-bend.

A layered diffuser-channel heat exchanger may comprise a plurality of fluid channel layers and a plurality of diffuser fin layers interleaved with the plurality of fluid channel layers. Each fluid channel layer of the plurality of fluid channel layers may have a first surface, a second surface opposite the first surface, and a fluid channel located between the first surface and the second surface.