Fluid Distributor for Microchannel Heat Exchanger

This application is a continuation-in-part of U.S. Non-Provisional application Ser. No. 18/815,101, filed Aug. 26, 2024, which claims the benefit of U.S. Provisional Application No. 63/535,943, filed Aug. 31, 2023, the disclosures of which are incorporated herein by reference in their entirety.

This invention relates to the field of heat exchangers, and more particularly, a fluid distributor for heat exchangers.

Described herein is a fluid distributor for a heat exchanger. The fluid distributor comprises a header comprising of compartments separated by walls, wherein a plurality of tubes associated with a heat exchange section of the heat exchanger are fluidically connected to at least one of the compartments. The fluid distributor further comprises a distribution tube extending longitudinally along the compartments of the header through the walls. The distribution tube comprises a plurality of cavities extending longitudinally along a length of the distribution tube and configured radially around a central axis of the distribution tube, wherein each of the cavities comprises one or more ports opening in the compartments. Further, the fluid distributor comprises a supply tube fluidically connected to the distribution tube or to a supply tube compartment of the header and configured to supply a working fluid into the distribution tube.

In one or more embodiments, the fluid distributor comprises a flow restrictor configured within the supply tube or between the supply tube and the distribution tube, wherein the flow restrictor is an annular member having a central opening that is configured in line with the distribution tube and having a predefined gap therebetween.

In one or more embodiments, the central opening of the flow restrictor and the distribution tube have equal diameters. In one or more embodiments, the central opening of the flow restrictor is in a range of 10 to 80% of an orifice of the distribution tube.

In one or more embodiments, the fluid distributor comprises a swirl generator configured upstream of the distribution tube or within the supply tube, wherein the swirl generator is configured to cause the working fluid, supplied by the supply tube, to move in a swirl motion.

In one or more embodiments, the swirl generator comprises a housing having a plurality of grooves with curved profiles being configured on an inner wall surface of the housing, the grooves extending radially and circumferentially along the inner wall surface.

In one or more embodiments, the swirl generator comprises a housing and a plurality of blades extending radially from a central longitudinal axis of the housing and oriented at predefined angles from a radial plane.

In one or more embodiments, the swirl generator comprises a housing, and a plurality of blades extending radially from a central longitudinal axis of the housing, wherein each of the blades comprises a first section and a second section with a slit extending at a predefined angle from the first section.

In one or more embodiments, the swirl generator comprises a housing, and a plurality of swirl-generating elements having a predefined shape and at least one curved surface, protruding from or configured on an inner wall surface of the housing.

In one or more embodiments, the swirl generator comprises a ring protruding from or configured on the inner wall surface of the housing, the ring is configured coaxially within the housing with the plurality of swirl-generating elements configured above and/or below the ring.

In one or more embodiments, the swirl generator comprises a housing and a spiral assembly disposed coaxially with a central longitudinal axis of the housing and fixedly connected to an inner wall surface of the housing to jointly form a spiral flow channel.

In one or more embodiments, the supply tube is axially connected to the supply tube compartment or the distribution tube.

In one or more embodiments, the supply tube is radially connected to the supply tube compartment or the distribution tube.

In one or more embodiments, the supply tube is configured off-centered from the central axis of the distribution tube.

In one or more embodiments, the supply tube is directly connected to the distribution tube, wherein the distribution tube and the supply tube have equal diameters.

In one or more embodiments, the header is a vertical header of the heat exchanger and the supply tube is fluidically connected to terminal supply tube compartment.

In one or more embodiments, the fluid distributor comprises one or more swirl-generating elements being configured within or on an inner wall surface of the supply tube compartment, the supply tube, or both.

In one or more embodiments, the supply tube is radially connected at a predefined position on the supply tube compartment of the header, such that the orifice of the distribution tube opens below, above, or at a same level of the predefined position or the supply tube.

In one or more embodiments, the supply tube compartment comprises a baffle having a central opening and a plurality of openings configured radially around the central opening. The baffle is coaxially configured within the supply tube compartment such that a bottom end or the orifice of the distribution tube remains connected to the central opening and the supply tube is connected radially to the supply tube compartment above the baffle.

In one or more embodiments, the supply tube compartment comprises a baffle having a plurality of openings. The baffle is coaxially configured within the supply tube compartment of the header with the distribution tube extending longitudinally through the baffle such that a bottom end or the orifice of the distribution tube opens below the baffle and the supply tube is radially connected to the supply tube compartment above the baffle.

In one or more embodiments, the supply tube is configured off-centered from the central axis of the distribution tube.

Also described herein is a heat exchanger comprising the fluid distributor.

Described herein is a fluid distributor for a heat exchanger, the fluid distributor comprising: a supply tube having an outlet end and an inlet end; a first distribution tube in vertical communication with the outlet end of the supply tube; a second distribution tube disposed parallel to the first distribution tube; and a connecting tube having one end in communication with the first distribution tube and the other end in communication with the second distribution tube, wherein a spiral assembly fixedly connected to an inner surface of the supply tube is disposed inside at least a part of tube section in the supply tube, and the spiral assembly and the supply tube together form a spiral flow channel.

In one or more embodiments, the spiral assembly comprises a support portion disposed coaxially with a central axis of the supply tube, and a flow guiding structure spirally disposed around the support portion to form the spiral flow channel together with the inner surface of the supply tube.

In one or more embodiments, the spiral flow channel is spaced apart from the inlet end of the supply tube or the outlet end of the supply tube by a specified distance.

In one or more embodiments, the fluid distributor comprises: a plurality of first distribution tube outlets disposed along a length extension direction of the first distribution tube and separately disposed on a side of the first distribution tube facing the second distribution tube; and a plurality of second distribution tube outlets disposed along a length extension direction of the second distribution tube and separately disposed on a side of the second distribution tube facing the first distribution tube.

In one or more embodiments, a plurality of connecting tubes are disposed perpendicular to the first distribution tube and the second distribution tube and along the length extension direction of the first distribution tube and the second distribution tube.

In one or more embodiments, the first distribution tube outlets and/or the second distribution tube outlets are symmetrically arranged about the outlet end of the supply tube in the length extension direction of the first distribution tube and/or the second distribution tube.

In one or more embodiments, the plurality of connecting tubes are symmetrically arranged about the outlet end of the supply tube in the length extension direction of the first distribution tube and the second distribution tube.

In one or more embodiments, at least one of the plurality of connecting tubes is disposed at a position corresponding to the outlet end of the supply tube.

In one or more embodiments, in the length extension direction of the first distribution tube or the second distribution tube, a distance between two adjacent connecting tubes in the plurality of connecting tubes varies.

Also described herein is a heat exchanger comprising the fluid distributor.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, features, and techniques of the subject disclosure will become more apparent from the following description taken in conjunction with the drawings.

The following is a detailed description of embodiments depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject disclosure as defined by the appended claims.

Various terms are used herein. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the subject disclosure, the components of this invention. Described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower,” “first”, “second” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the header, distribution tube, refrigerant distributor, multichannel tubes, heat exchanger, supply tube, and corresponding components, described herein may be oriented in any desired direction.

Microchannel heat exchangers (MCHX) employing microchannel tubes are important components in heat pump systems, facilitating efficient heat transfer between different fluid streams. These heat exchangers are employed in a wide range of applications, including residential and commercial heating, ventilation, and air conditioning (HVAC) systems. An important challenge in the design and operation of MCHX is the effective distribution of the working fluid (refrigerant) across the microchannel tubes to ensure optimal heat transfer performance and capacity. The working fluid may be in two phases, vapor and liquid. When two phases are present, the two phases must be mixed to facilitate effective distribution.

Mal-distribution of the working fluid within MCHX can lead to significant imbalances in thermal characteristics and a reduction in overall heat transfer efficiency. One of the primary concerns associated with mal-distribution is the varying heat transfer coefficient between the vapor and liquid phases. Due to the lower heat transfer coefficient of the vapor phase, an uneven distribution can result in localized areas of reduced heat transfer, leading to decreased capacity and overall performance of the heat pump system.

Furthermore, the problem of mal-distribution becomes exacerbated when MCHX is configured with vertical headers. In such configurations, the influence of gravity plays a role in causing separation between the vapor and liquid phases due to the differing densities of these phases. This vapor-liquid separation may lead to increased mal-distribution of fluid across the microchannel tubes and compromise the overall heat transfer efficiency of the system.

There is a need for a solution to address the challenges posed by mal-distribution in MCHX, particularly in MCHX having vertical headers, by providing an improved and effective fluid distribution system that helps the MCHX achieve a more uniform distribution of the working fluid phases across all the microchannel tubes, thereby enhancing the overall thermal performance of the MCHX.

The header (or manifold) forms a conduit to deliver working fluid to the heat exchange tubes. The header may be vertical, horizontal or some intermediate angle between vertical and horizontal. Additionally, the flow of the working fluid may be in any direction (bottom to top, top to bottom or side to side). The header includes compartments dedicated to a group of heat exchange tubes which is a subset of the total number of heat exchange tubes. A distribution tube located within the header provides working fluid to the compartments. The distribution tube has cavities extending longitudinally. Each distribution tube cavity provides working fluid to one or more compartments of the header.

A supply tube provides the working fluid to the header. The supply tube may be directly connected to the distribution tube or may be fluidly connected to a supply tube compartment in the header. The supply tube compartment may be located at one end of the header (a terminal supply tube compartment) or may be located at some intermediate point of the header (an intermediate supply tube compartment). When the supply tube compartment is a terminal supply tube compartment, the distribution tube has one or more orifices to allow the working fluid to enter the distribution tube. When the supply tube compartment is an intermediate supply tube compartment, the distribution tube has two or more orifices to allow the working fluid to enter the distribution tube. The supply tube compartment may provide a space to mix the phases of the working fluid. Mixing the phases of the working fluid can be achieved by placement of the supply tube outlet relative to the distribution tube orifice(s), the structure of the distribution tube orifice, the structure of the supply tube compartment, or a combination thereof.

When the supply tube is directly connected to the distribution tube, the distribution tube and the supply tube may have equal internal diameters or may have different internal diameters. Further, the distribution tube has one or more orifices opening in or located within the supply tube. The orifice(s) may be before or after a bend in the supply tube. The terminal end of the supply tube or the distribution tube orifice may include a mixing element such as a swirl generator as described below.

When the supply tube connects to the header the working fluid enters a supply tube compartment. The supply tube compartment may be terminal or intermediate as described above. When the supply tube is a terminal supply tube compartment the location of the supply tube relative to the distribution tube orifice and the distribution tube axis can affect working fluid phase mixing. Additionally, the supply tube compartment structure can be used to enhance working fluid phase mixing. When the supply tube compartment is intermediate the structure of the supply tube compartment as well as the placement of the supply tube outlet can be used to enhance the working fluid phase mixing.

Referring to, the fluid distributorfor a heat exchanger is disclosed. The fluid distributoror the heat exchanger can include a headercomprising one or more hollow compartments-to-N (collectively designated as compartments, herein) being partitioned by one or more walls-to-N (collectively referred to as walls or partition walls, herein). The headercan be a hollow member having parallelly placed wallsseparated by a predefined distance to create the compartmentstherewithin. The compartmentsmay have equal volumes or the volumes may vary. When the compartment volumes vary the number of microchannel tubes associated with the compartments may vary as well. The headermay have a cylindrical profile or a substantially curved profile with flat bases at the two opposite ends but is not limited to the like. Further, a plurality of microchannel tubes (collectively designated as MCHX tubes, herein) associated with a heat exchange section or coils of the heat exchanger can be fluidically connected to at least one of the compartments-to-N.

In addition, the header includes a distribution tubeextending longitudinally along the compartmentsof the headerthrough the partition walls. The distribution tubecan include a plurality of cavities-to-(collectively designated as cavities,, herein) extending longitudinally along a length of the distribution tubeand configured radially around a central axis (A-A′) of the distribution tubein a distribution tube casing-. The cavities may be pie-shaped as shown in the Figures or may form concentric rings. Further, as shown in, each of the cavitiescan include one or more ports (P) opening in at least one of the partitioned compartmentsof the header. When the cavities form concentric rings the exterior of the distribution tube may have a stepped shape resulting from the termination of the ring after the one or more ports opening in the destination compartment.

The distribution tubecan be a rod-shaped member-having a plurality of axial hollow passagesextending longitudinally along the length and configured radially around a central axis (A-A′) of the rod member to form the plurality of cavities. Further, additional hollow passages can extend radially from the vertical passagesand open into the interior of the headerto form the ports (P) of the cavities.

Further, the flow distributor includes a supply tubefluidically connected to distribution tubeor to the headerand configured to supply a fluid into the distribution tubesuch that the fluid is more uniformly mixed and supplied into the cavitiesand further into the MCHX tubesof the heat exchange section via the ports (P) of the corresponding cavities.

An exemplary headeris a vertical headerof the heat exchanger but, as discussed above, is not limited thereto. In one or more embodiments, the supply tubecan be directly fluidically connected to the distribution tube. The distribution tubecan include one or more orifices opening in or located within the supply tube, such that the fluid supplied by the supply tubemay directly enter into each of the cavities(or orifice) of the distribution tube. Further, in one or more embodiments, the orifice(s) of the distribution tubemay be before or after a bend in the supply tubeto axially supply the fluid into the distribution tube. Furthermore, in one or more embodiments, the supply tubecan be fluidically connected to a bottom-most compartment-, as the supply tube compartment, among the compartmentsof the header, with an orifice (O) of the distribution tubeopening in the bottom-most compartment-. The top end of the distribution tube(or the cavities) may be closed and the orifice (O) at the bottom end of the distribution tubemay open in the supply tube compartment-, such that the fluid supplied by the supply tubemay enter into each of the cavities(or orifice) of the distribution tubevia the supply tube compartment-and further flow into the MCHX tubesvia the corresponding compartmentsand the ports (P) of the cavities.