Refrigerant heat exchanger with integral multipass and flow distribution technology

1 . A microtube heat exchanger for cooling or heating refrigerant fluid of a heat exchange system, the microtube heat exchanger comprising:

a tube stack comprising a plurality of microtubes aligned substantially parallel to each other to form the tube stack, wherein refrigerant fluid is configured to pass though the plurality of microtubes so that heat can be transferred between the refrigerant fluid and an external fluid flowing past an exterior of the plurality of microtubes;

a first header disposed on a first end of the tube stack and comprising an inlet port coupled with a refrigerant fluid inlet of the heat exchanger and through which refrigerant fluid traveling in a first direction is introduced into the tube stack; and

a second header disposed at a second end of the tube stack and comprising a second header passage configured to receive refrigerant fluid traveling in the first direction through some of the plurality of microtubes and discharge the received refrigerant fluid in a second direction to some of the plurality of microtubes,

wherein the first header further comprises a first header passage configured to receive refrigerant fluid traveling in the second direction through some of the plurality of microtubes and discharge the received refrigerant fluid in the first direction to some of the plurality of microtubes, and

wherein the second header further comprises an outlet port configured to receive refrigerant fluid traveling through some of the plurality of microtubes in the first direction and discharge the received refrigerant fluid to a refrigerant fluid outlet of the heat exchanger;

wherein each of the first header passage and the second header passage each comprise:

an inlet surface including an inlet port configured to receive the refrigerant fluid from the tube stack;

an outlet surface including an outlet port configured to discharge the received fluid toward the tube stack; and

a channel fluidly coupling the inlet port and the outlet port;

wherein the channel is substantially a 180-degree U-shaped channel fluidly coupling the inlet port and the outlet port; and

wherein the channel forms a continuous arc free from 90-degree turns.

2 . The microtube heat exchanger of claim 1 , wherein, for each of the first header passage and second header passage, the inlet surface and outlet surface are substantially co-planar with each other.

3 . The microtube heat exchanger of claim 1 , wherein, for each of the first header passage and second header passage:

the inlet surface has a plurality of the inlet ports; and

the outlet surface has a plurality of the outlet ports,

wherein each of the first header passage and second header passage further comprises a plurality of the channels, each of the plurality of the channels fluidly coupling one of the plurality of the inlet ports to one of the plurality of the outlet ports.

4 . The microtube heat exchanger of claim 1 , wherein each of the first header passage and the second header passage further comprises a gasket configured to seal against an end plate of the tube stack and fluidly separate the inlet surface and the outlet surface.

5 . The microtube heat exchanger of claim 1 , wherein:

the first header comprises a plurality of the first header passages and is disposed within an inlet-side housing of the heat exchanger; and

the second header comprises a plurality of the second header passages and is disposed within an outlet-side housing of the heat exchanger.

6 . The microtube heat exchanger of claim 1 , wherein each of the first header passage and second header passage comprises:

a U-turn surface disposed to face the tube stack;

a raised perimeter protruding from the U-turn surface toward the tube stack and comprising a gasket configured to seal against an end plate of the tube stack to form a sealed volume between the U-turn surface and the tube stack,

wherein the gasket seals against the end plate such that the U-turn surface and sealed volume are configured to receive refrigerant fluid traveling from a first group of microtubes of the plurality of microtubes and discharge refrigerant fluid to a second group of tubes of the plurality of the microtubes.

7 . The microtube heat exchanger of claim 1 , wherein the plurality of microtubes have an inner diameter in a range from 254 micrometers to 2,497 micrometers.

8 . A microtube heat exchanger for cooling or heating refrigerant fluid of a heat exchange system, the microtube heat exchanger comprising:

a tube stack comprising a plurality of microtubes aligned substantially parallel to each other to form the tube stack, wherein refrigerant fluid is configured to pass though the plurality of microtubes so that heat can be transferred between the refrigerant fluid and an external fluid flowing past an exterior of the plurality of microtubes;

a first header disposed on a first end of the tube stack and comprising an inlet port coupled with a refrigerant fluid inlet of the heat exchanger and through which refrigerant fluid traveling in a first direction is introduced into the tube stack; and

a second header disposed at a second end of the tube stack and comprising a second header passage configured to receive refrigerant fluid traveling in the first direction through some of the plurality of microtubes and discharge the received refrigerant fluid in a second direction to some of the plurality of microtubes,

wherein the first header further comprises a first header passage configured to receive refrigerant fluid traveling in the second direction through some of the plurality of microtubes and discharge the received refrigerant fluid in the first direction to some of the plurality of microtubes, and

wherein the second header further comprises an outlet port configured to receive refrigerant fluid traveling through some of the plurality of microtubes in the first direction and discharge the received refrigerant fluid to a refrigerant fluid outlet of the heat exchanger;

wherein first header passage and the second header passage each comprise a surface segregated into a plurality of separate surface portions by a groove projecting outward from the surface, the separate surface portions each being co-planar with each other, and each of the separate surface portions being an inlet surface including an inlet port or an outlet surface including an outlet port.

9 . The microtube heat exchanger of claim 8 , wherein the plurality of separate surface portions includes a first portion, a second portion, and a third portion, the second portion having a length measured along the surface that is greater than a sum of a length of the first portion measured along the surface and a length of the third portion measured along the surface.

10 . A microtube heat exchanger for cooling or heating refrigerant fluid of a heat exchange system, the microtube heat exchanger comprising:

a tube stack comprising a plurality of microtubes aligned substantially parallel to each other to form the tube stack, wherein refrigerant fluid is configured to pass though the plurality of microtubes so that heat can be transferred between the refrigerant fluid and an external fluid flowing past an exterior of the plurality of microtubes;

a first header disposed on a first end of the tube stack and comprising an inlet port coupled with a refrigerant fluid inlet of the heat exchanger and through which refrigerant fluid traveling in a first direction is introduced into the tube stack; and

a second header disposed at a second end of the tube stack and comprising a second header passage configured to receive refrigerant fluid traveling in the first direction through some of the plurality of microtubes and discharge the received refrigerant fluid in a second direction to some of the plurality of microtubes,

wherein the first header further comprises a first header passage configured to receive refrigerant fluid traveling in the second direction through some of the plurality of microtubes and discharge the received refrigerant fluid in the first direction to some of the plurality of microtubes, and

wherein the second header further comprises an outlet port configured to receive refrigerant fluid traveling through some of the plurality of microtubes in the first direction and discharge the received refrigerant fluid to a refrigerant fluid outlet of the heat exchanger;

wherein each of the first header passage and the second header passage each comprise:

an inlet surface including an inlet port configured to receive the refrigerant fluid from the tube stack;

an outlet surface including an outlet port configured to discharge the received fluid toward the tube stack; and

a channel fluidly coupling the inlet port and the outlet port;

wherein the first header passage and the second header passage each further comprise a curved inlet surface transitioning between the inlet surface and the inlet port, and a curved outlet surface transitioning between the outlet surface and the outlet port.