Patent Description:
Counterflow is a configuration for a heat exchanger that may be configured to maximize heat transfer. The configuration may reduce thermal stress by enabling a lower local temperature difference. Such configurations, however, may result in a high pressure drop, which could also induce stress challenges within the heat exchanger. <CIT> relates to a heat exchanger with a radially converging manifold. <CIT> relates to a heat exchanger with a distribution device.

<CIT> discloses a heat exchanger according to the preamble of claim <NUM>.

Disclosed is a heat exchanger including: a core having a first side and a second side, a top and a bottom; an inlet header located at the top of the first side, the inlet header having plural inlet tubes, the plural inlet tubes include a first inlet tube stacked against the first side of the heat exchanger, a second inlet tube stacked against the first inlet tube and a third inlet tube stacked against the second inlet tube; an outlet header located at the bottom of the second side, the outlet header having plural outlet tubes, the plural outlet tubes include a first outlet tube stacked against the second side of the heat exchanger, a second outlet tube stacked against the first outlet tube and a third outlet tube stacked against the second outlet tube, wherein the first inlet and outlet tubes have a same length as each other, the second inlet and outlet tubes have the same length as each other and are longer than the first inlet and outlet tubes, and the third inlet and outlet tubes have a same length as each other and are longer than the second inlet and outlet tubes; and core channels within the core that extend from the first side to the second side of the heat exchanger, wherein the core channels are fluidly isolated from each other within the core and connect the inlet tubes to the outlet tubes such that: the first inlet tube and third outlet tube are connected by the channels; the second inlet tube and second outlet tube are connected by the channels; and the third inlet tube and first outlet tube are connected by the channels.

In addition to one or more of the aspects of the heat exchanger or as an alternate the inlet tubes and the outlet tubes each define a header end and a terminal end; and each tube tapers towards the terminal end.

In addition to one or more of the aspects of the heat exchanger or as an alternate the heat exchanger is a counterflow heat exchanger.

In addition to one or more of the aspects of the heat exchanger or as an alternate the inlet tubes are connected to a same number of the core channels as each other; and the outlet tubes are connected to a same number of the core channels as each other.

In addition to one or more of the aspects of the heat exchanger or as an alternate the heat exchanger includes a first baffle on one side of the core channels; and a second baffle on another side of the core channels, wherein the first and second baffles are configured to direct a gas flow between the first side and the second side of the heat exchanger.

In addition to one or more of the aspects of the heat exchanger or as an alternate the heat exchanger includes a first set of heat fins that are coupled to the core channels and the first baffle; and a second set of heat finds that are coupled to the core channels and the second baffle.

In addition to one or more of the aspects of the heat exchanger or as an alternate the heat exchanger includes a case extending from the first side to the second side to surround the core and form a flow boundary for the gas flow.

In addition to one or more of the aspects of the heat exchanger or as an alternate the tubes and channels have a round cross section.

Disclosed is a method of manufacturing a heat exchanger, including: defining the heat exchanger to include: a core having a first side and a second side, a top and a bottom; an inlet header located at the top of the first side, the inlet header having plural inlet tubes, the plural inlet tubes include a first inlet tube stacked against the first side of the heat exchanger, a second inlet tube stacked against the first inlet tube and a third inlet tube stacked against the second inlet tube; an outlet header located at the bottom of the second side, the outlet header having plural outlet tubes, the plural outlet tubes include a first outlet tube stacked against the second side of the heat exchanger, a second outlet tube stacked against the first outlet tube and a third outlet tube stacked against the second outlet tube, wherein the first inlet and outlet tubes have a same length as each other, the second inlet and outlet tubes have the same length as each other and are longer than the first inlet and outlet tubes, and the third inlet and outlet tubes have a same length as each other and are longer than the second inlet and outlet tubes; and core channels within the core that extend from the first side to the second side of the heat exchanger, wherein the core channels are fluidly isolated from each other within the core and connect the inlet tubes to the outlet tubes such that: the first inlet tube and third outlet tube are connected by the channels; the second inlet tube and second outlet tube are connected by the channels; and the third inlet tube and first outlet tube are connected by the channels; and additively manufacturing the heat exchanger.

In addition to one or more of the aspects of the method or as an alternate, the method includes defining the heat exchanger such that: the inlet tubes and the outlet tubes each define a header end and a terminal end; and each tube tapers towards the terminal end.

In addition to one or more of the aspects of the method or as an alternate, the method includes defining the heat exchanger such that the heat exchanger is a crossflow heat exchanger.

In addition to one or more of the aspects of the method or as an alternate, the method includes defining the heat exchanger such that: the inlet tubes are connected to a same number of the core channels as each other; and the outlet tubes are connected to a same number of the core channels as each other.

In addition to one or more of the aspects of the method or as an alternate, the method includes defining the heat exchanger to include: a first baffle on one side of the core channels; and a second baffle on another side of the core channels, wherein the first and second baffles are configured to direct a gas flow between the first side and the second side of the heat exchanger.

In addition to one or more of the aspects of the method or as an alternate, the method includes defining the heat exchanger to include: a first set of heat fins that are coupled to the core channels and the first baffle; and a second set of heat finds that are coupled to the core channels and the second baffle.

In addition to one or more of the aspects of the method or as an alternate, the method includes defining the heat exchanger to include a case extending from the first side to the second side to surround the core and form a flow boundary for the gas flow.

In addition to one or more of the aspects of the method or as an alternate, tubes and channels have a round cross section.

Turning to <FIG> and <FIG>, as provided in greater detail below, the embodiments are directed to a counterflow heat exchanger <NUM> configured to reduce a pressure drop, and increase heat transfer, in the working fluid <NUM>. The heat exchanger <NUM> therefore enables a greater amount of heat transfer between the working fluid <NUM> and a gas flow <NUM> through the heat exchanger <NUM>.

The heat exchanger <NUM> may be an additively manufactured, or conventionally manufactured, crossflow heat exchanger having a first end <NUM> and a second end <NUM> separated from each other by a depth D of the heat exchanger <NUM>. The first end <NUM> is a front end and the second end <NUM> is a back end of the heat exchanger <NUM>. A case or shell <NUM> surrounds a core <NUM> of the heat exchanger <NUM> and the gas flow <NUM> may flow through the core <NUM> of the heat exchanger <NUM>, e.g., through the shell <NUM>. That is, the shell <NUM> forms a flow boundary through the core <NUM> of the heat exchanger <NUM>. An outer shape of the heat exchanger <NUM> is square, though other shapes are within the scope of the embodiments. The shell <NUM> defines a top 130A, a bottom 130B, and opposite sides 130C, 130D of the heat exchanger <NUM>. The top 130A and bottom 130B are separated from each other by a height H of the heat exchanger <NUM>. The sides 130C, 130D are separated from each other by a width W of the heat exchanger <NUM>.

The heat exchanger <NUM> has a first header <NUM>, which may be an inlet header, on the top of the first end <NUM>. A second header <NUM>, which may be an outlet header, is on the bottom of the second end <NUM> of the heat exchanger <NUM>. The first header <NUM> has sets of inlet distribution tubes (inlet tubes) <NUM> at the inlet transition region 110A of the first end <NUM> of the heat exchanger <NUM>, e.g., at the transition to the core flow of the working fluid <NUM>. The sets of inlet tubes <NUM> includes first and second sets 142A, 142B that are widthwise spaced apart from each other and extend heightwise along the first end <NUM> of the heat exchanger <NUM>. The second header <NUM> has sets of outlet distribution tubes (outlet tubes) <NUM> at the outlet transition region 110B of the second end <NUM> of the heat exchanger <NUM>, e.g., at the transition from the core flow of the working fluid <NUM>. The sets of outlet tubes <NUM> includes first and second sets 144A, 144B that are widthwise spaced apart from each other and extend heightwise along the second end <NUM> of the heat exchanger <NUM>. The sets of tubes on the of the first and second headers <NUM>, <NUM> are fluidly coupled to each other as described in greater detail below. The first and second headers <NUM>, <NUM> may be utilized to transport the working fluid <NUM> though the heat exchanger <NUM>, e.g., between the first and second ends <NUM>, <NUM> of the heat exchanger <NUM>.

A third header <NUM> and a fourth header <NUM> are fluidly coupled to each other, similarly to the first and second headers <NUM>, <NUM>. The third header <NUM>, which may be another inlet header, is located at the bottom of the first end <NUM> of the heat exchanger <NUM>. The fourth header <NUM>, which may be another outlet header, is located at the top of the second end <NUM> of the heat exchanger <NUM>. That is, the third and fourth headers <NUM>, <NUM> are on heightwise opposite sides of the heat exchanger <NUM> compared with the first and second headers <NUM>, <NUM>. The third header <NUM> has sets of inlet tubes <NUM>, including first and second sets 146A, 146B, that are widthwise spaced apart from each other and extend heightwise along the first end <NUM> of the heat exchanger <NUM>. Similar to the first and second headers <NUM>, <NUM>, the inlet tubes <NUM> are fluidly coupled with sets outlet tubes <NUM>, including first and second sets 148A, 148B of the fourth header <NUM>. The sets of outlet tubes <NUM> are widthwise spaced apart from each other and extend heightwise along the second end <NUM> of the heat exchanger <NUM>. The third and fourth headers <NUM>, <NUM> have the same function of transporting the working fluid <NUM> through the heat exchanger <NUM> as the first and second headers <NUM>, <NUM>. However, the third and fourth headers <NUM>, <NUM> are fluidly isolated from the first and second headers <NUM>, <NUM>. It is to be appreciated that the third and fourth headers <NUM>, <NUM>, and related core flow therebetween of the working fluid <NUM>, is optional.

A first perimeter lip <NUM> extends around a perimeter of the first end <NUM> and a second perimeter lip <NUM> extends around a perimeter of the second end <NUM>. The perimeter lips <NUM>, <NUM> are sized to be large enough to provide a sealing surface for gas flow <NUM>.

Turning to <FIG> and <FIG>, the first and second headers <NUM>, <NUM> are configured the same as each other, so focus will be on the first header <NUM>. The first header <NUM> has an inlet manifold (or manifold) <NUM>. The first set of inlet tubes 142A has plural, e.g., two or more, though illustrated as three inlet tubes including first, second and third inlet tubes 142A1-A3 that are stacked, one on top of the other. Each of the inlet tubes 142A1-142A3 has a header end (or manifold end) 180A-C. At the header end 180A-C, the first inlet tube 142A1 is an interior tube, the second inlet tube 142A2 is an intermediate tube and the third inlet tube 142A3 is an exterior tube.

Core channels (or channels) <NUM> trace a straight line path through the core of the heat exchanger <NUM> and fluidly couple the inlet tubes <NUM> to the outlet tubes <NUM>, as discussed in greater detail below. The channels <NUM> are fluidly isolated from each other within the core <NUM>. Baffles <NUM>, <NUM>, e.g., first and second baffles <NUM>, <NUM>, may be adjacent to each side of the channels <NUM> and extend through the depth of the heat exchanger <NUM>. Heat fins <NUM> may be formed to extend between the channels <NUM> and the baffles <NUM>. As shown in <FIG>, there may be a plurality of sets of the channels 190A, 190B, 190C connected to the set of inlet tubes <NUM> via ports <NUM> in the inlet tubes <NUM>.

Turning to <FIG>, each of the inlet tubes 142A1-A3 on the first end <NUM> of the heat exchanger <NUM> has a terminal end 182A-C. From the header ends 180A-C to the terminal ends 182A-C, the third inlet tube 142A3 is longer than the second inlet tube 142A2, which is longer than the first inlet tube 142A1. The first inlet tube 142A1, is connected to the core channels <NUM> along its length, e.g., along the heightwise direction. The second inlet tube 142A2 is connected to channels <NUM> along its length that extends past the first inlet tube 142A1, e.g., in the heightwise downward direction. The third inlet tube 142A3 is connected to channels <NUM> along its length that extends past the second inlet tube 142A2, in the heightwise downward direction. In one embodiment, the inlet tubes <NUM> are connected to a same number of channels <NUM> as each other. As shown, the inlet tubes <NUM> taper towards the terminal ends 182A-C. By limiting a length and distribution requirements of each inlet tube <NUM>, the pressure losses are reduced. In addition, by reducing the diameter of each tube <NUM> towards its terminal ends 182A-C, pressure losses are further reduced. Thus the efficiency of heat transfer from the working fluid <NUM> to the gas flow <NUM> in the core <NUM> is increased.

On the second end <NUM> of the heat exchanger <NUM>, the second header <NUM> has an outlet manifold (or manifold) <NUM>. The first set of outlet tubes 144A has plural, e.g., two or more, though illustrated as three tubes including first, second and third outlet tubes 144A1-A3 that are stacked, one on top of the other. Each of the outlet tubes 144A1-144A3 has a header end (or manifold end) 230A-C. At the header end 230A-C, the first outlet tube 144A1 is an interior tube, the second outlet tube 144A2 is an intermediate tube and the third outlet tube 144A3 is an exterior tube.

Each of the outlet tubes 144A1-A3 has a terminal end 240A-C. From the manifold <NUM> to the terminal ends 240A-C, the third outlet tube 144A3 is longer than the second outlet tube 144A2, which is longer than the first outlet tube 144A1. The first outlet tube 144A1, is connected to channels <NUM> along its length. The second outlet tube 144A2 is connected to channels <NUM> along its length that extends past the first outlet tube 144A1, e.g., in the heightwise upward direction. The third outlet tube 144A3 is connected to channels <NUM> along its length that extends past the second outlet tube 144A2, in the heightwise upward direction.

The first inlet and outlet tubes 142A1, 144A1 may be the same length as each other, the second inlet and outlet tubes 142A2, 144A2 may be the same length as each other, and the third inlet and outlet tubes 142A3, 144A3 may be the same length as each other. The outlet tubes <NUM> taper towards the terminal ends 240A-C. As indicated, the outlet tubes <NUM> are the same configuration as the inlet tubes <NUM>, except that they are inverted in the heightwise direction. As with the inlet tubes <NUM>, by limiting a length and distribution requirements of each outlet tube <NUM>, the pressure losses are reduced. In addition, by reducing the diameter of each outlet tube <NUM> towards its terminal ends 240A-C, more uniform flow through channels <NUM> is produced. Thus the efficiency of heat transfer from the working fluid <NUM> to the gas flow <NUM> in the core <NUM> is further increased.

As shown in <FIG>, the channels <NUM> fluidly couple the first inlet tube 142A1 with the third outlet tube 144A3, the second inlet tube 142A2 with the second outlet tube 144A2 and the third inlet tube 142A3 with the first outlet tube 144A2. The channels <NUM> also fluidly couple the terminal end 182A of the first inlet tube 142A1 with the terminal end 240B of the second outlet tube 144A2 and the terminal end 182B of the second inlet tube 142A2 with the terminal end 240A of the first outlet tube 144B2. This fluid coupling configuration helps to maintain equal flow within the tubes.

The above embodiments provide a heat exchanger <NUM> that is compact and efficient. The heat exchanger <NUM> is suitable for high pressure and temperature applications. For example, fluid <NUM> will generally be at a higher pressure, such as <NUM> bar, and density than fluid <NUM>. The stacked design of the tubes provides a direct path for the working fluid <NUM> to enter the core channels <NUM>, without impeding fluid <NUM>, reducing pressure drop and improving heat transfer. In one embodiment, the tubes and channels have a round cross section.

Claim 1:
A heat exchanger comprising:
a core (<NUM>) having a first side and a second side, a top and a bottom;
an inlet header (<NUM>) located at the top of the first side, the inlet header having plural inlet tubes (<NUM>), the plural inlet tubes include a first inlet tube stacked against the first side of the heat exchanger, a second inlet tube stacked against the first inlet tube and a third inlet tube stacked against the second inlet tube;
an outlet header (<NUM>) located at the bottom of the second side, the outlet header having plural outlet tubes (<NUM>), the plural outlet tubes include a first outlet tube stacked against the second side of the heat exchanger, a second outlet tube stacked against the first outlet tube and a third outlet tube stacked against the second outlet tube,
wherein the first inlet and outlet tubes (<NUM>, <NUM>) have a same length as each other, the second inlet and outlet tubes have the same length as each other and are longer than the first inlet and outlet tubes, and the third inlet and outlet tubes have a same length as each other and are longer than the second inlet and outlet tubes; and
core channels (<NUM>) within the core that extend from the first side to the second side of the heat exchanger, wherein the core channels are fluidly isolated from each other within the core and connect the inlet tubes to the outlet tubes, said heat exchanger being characterized in that: the first inlet tube and third outlet tube are connected by the channels; the second inlet tube and second outlet tube are connected by the channels; and the third inlet tube and first outlet tube are connected by the channels.