Patent Application
20250137738
This invention relates to a microchannel heat exchanger.
Described herein is a heat exchanger. The heat exchanger comprises an inlet header that comprises first compartments separated by first walls, a plurality of microchannel tubes extending between and in fluidic connection with the first compartments and an outlet header of the heat exchanger, a first distributor comprising an inlet port and a plurality of outlet ports, wherein a plurality of feeder pipes is configured between the first compartments of the inlet header and the outlet ports of the first distributor, such that each of the first compartments remains fluidically connected to one of the outlet ports of the first distributor by one of the feeder pipes to allow flow of an equal volume of fluid from the first distributor into each of the first compartments, and a second distributor configured within the first compartments of the inlet header, the second distributor configured to mix and allow uniform flow of fluid into each of the microchannel tubes of the first compartments.
In one or more embodiments, the first distributor comprises a housing of a shape that comprises the inlet port at a first end of the housing and the plurality of outlet ports at a second end of the housing, wherein the inlet port is in fluidic communication with the plurality of outlet ports via a plurality of fluidic passages extending within the housing.
In one or more embodiments, the first distributor has a solid conical shape that comprises a substantially circular base, and a curved lateral surface extending from a vortex end of the first distributor to the circular base, wherein the first distributor comprises the inlet port at the vortex end, and the plurality of outlet ports being configured circumferentially around the circular base and in fluidic communication with the inlet port via a plurality of fluidic passages.
In one or more embodiments, each of the first compartments of the inlet header are hollow members, and the outlet header comprises hollow second compartments separated by second walls, wherein a first end of the plurality of microchannel tubes is fluidically connected to at least one of the first compartments of the inlet header and a second end of the corresponding tube is fluidically connected to at least one of the second compartments of the outlet header.
In one or more embodiments, the heat exchanger comprises a fluid collector fluidically connected to the second compartments of the outlet header, wherein the collector device is configured to receive and collect the fluid from each of the second compartments.
In one or more embodiments, the inlet header and the outlet header are configured in a vertical orientation, with the plurality of microchannel tubes extending between the inlet header and the outlet header.
In one or more embodiments, the feeder pipes associated with each of the first compartments is connected to a bottom end of the corresponding first compartment.
In one or more embodiments, the plurality of microchannel tubes is in a single-pass configuration.
In one or more embodiments, the plurality of microchannel tubes is in a multi-pass configuration comprising a predefined number of passes and a predefined number of turns.
In one or more embodiments, a number of tubes in a subsequent pass among the predefined number of passes is less than a number of tubes in a corresponding preceding pass.
In one or more embodiments, a number of tubes in a subsequent pass among the predefined number of passes is greater a number of tubes in a corresponding preceding pass.
In one or more embodiments, adjacent passes among the predefined number of passes are fluidically connected by a flow-mixing device.
In one or more embodiments, the heat exchange section comprises a plurality of refrigerant circuits, wherein each of the circuits comprises a group of microchannel tubes that is a subset of a total number of the plurality of microchannel tubes.
In one or more embodiments, the group of microchannel tubes associated with each of the refrigerant circuits comprises a predefined number of passes and a predefined number of turns.
In one or more embodiments, a first end of the group of microchannel tubes associated with each of the circuits is fluidically connected to one of the first compartments of the inlet header, and a second end of the group of microchannel tubes associated with each of the circuits is fluidically connected to one of the second compartments of the outlet header.
In one or more embodiments, the outlet ports of the first distributor are non-uniform in size such that different volume of fluid is provided in the first compartments of the inlet header.
In one or more embodiments, the feeder pipes have non-uniform predetermined diameters and predetermined lengths such that a predetermined target pressure drop is achieved in the feeder pipes.
In one or more embodiments, the second distributor comprises a distribution tube extending longitudinally through the first compartments, 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 each of the first compartments.
In one or more embodiments, the second distributor comprises an elongated member extending within the inlet header through the first compartments, the elongated member comprises a plurality of fluid passages substantially parallel to each other and extending longitudinally along a length of the elongated member, and a plurality of outlet ports disposed on a face of the elongated member and fluidically connected to at least one of the outlet ports, wherein at least one of the outlet ports open in each of the first compartments.
In one or more embodiments, the second distributor comprises a plurality of distribution tubes extending longitudinally through the inlet header, such that each of the distribution tubes extends up to and remains fluidically connected to one of the first compartments of the inlet header.
In one or more embodiments, the inlet header and/or the outlet header comprises one or more orifice plates configured coaxially within the corresponding compartments.
In one or more embodiments, the heat exchanger comprises a plurality of heat-dissipating fins in thermal contact with the plurality of microchannel tubes.
In one or more embodiments, the heat exchanger is associated with one or more of a heating, ventilation, air-conditioning, and cooling (HVAC) system, and a transport refrigeration unit.
Further described herein is a fluid distributor for a header comprising compartments separated by walls. The fluid distributor comprises a housing of a predefined shape that comprises an inlet port, and a plurality of outlet ports in fluidic communication with the inlet port via a plurality of fluidic passages extending within the housing. The fluid distributor further comprises a plurality of feeder pipes, wherein a first end of the feeder pipe is fluidically connected to one of the outlet ports of the housing, wherein a second end of the corresponding feeder pipe is configured to be fluidically connected to one of the compartments of the header to allow flow of an equal volume of fluid from the distributor into each of the compartments
In one or more embodiments, the housing has a solid conical shape that comprises a substantially circular base, and a curved lateral surface extending from a vortex end of the distributor to the circular base, wherein the housing comprises the inlet port at the vortex end, and the plurality of outlet ports being configured circumferentially around the circular base and in fluidic communication with the inlet port via the plurality of fluidic passages.
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 accompanying drawings are included to provide a further understanding of the subject disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the subject disclosure and, together with the description, serve to explain the principles of the subject disclosure.
In the drawings, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
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 inlet header, outlet header, first distributor, multichannel tubes, heat exchanger, feeder pipes, and corresponding components, described herein may be oriented in any desired direction.
Microchannel heat exchangers (MCHX), also known as parallel-flow heat exchangers employing microchannel tubes are important components in many applications including heat pump systems, facilitating efficient heat transfer between different fluid streams. Microchannel heat exchangers use large number of parallel refrigerant flow channels configured as flat tubes, among which the refrigerant is distributed and flown in a parallel manner. The heat exchange tubes are oriented generally substantially perpendicular to a refrigerant direction in the inlet, intermediate, and outlet manifolds that are in flow communication with the heat exchange tubes. These heat exchangers are employed in a wide range of applications, including residential and commercial heating, ventilation, and air conditioning and refrigeration (HVACR) systems. The primary reasons for the deployment of the MCHX technology are related to its superior performance, high degree of compactness, lower cost and lower charge utilization. MCHX are now utilized in both condensers and evaporator applications for multiple products and system designs and configurations. The evaporator applications, although promising greater benefits and rewards, are more challenging and problematic. An important challenge in the design and operation of MCHX as evaporator is the uniform distribution of the working fluid (refrigerant) across all microchannels and 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 homogeneously mixed to facilitate effective distribution.
As known, refrigerant maldistribution in parallel-flow heat exchangers occurs because of unequal pressure fields inside the channels and in the inlet and outlet manifolds. In the manifolds, the difference in length of the refrigerant paths, phase separation, and gravity are the primary factors responsible for maldistribution. Internal to the tube channels, variations in the heat transfer rate, airflow distribution, nonuniformity of channel hydraulic diameter, and gravity are the dominant factors. Maldistribution 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.
In the refrigerant systems utilizing microchannel heat exchangers, the inlet and outlet manifolds or headers usually have a conventional cylindrical shape with flat tubes inserted laterally such that the tube axis is substantially perpendicular to the header axis. When the two-phase flow enters the header, the vapor phase is usually separated from the liquid phase due to many factors mentioned before. Since the vapor phase occupies an overwhelmingly larger space than liquid and both phases flow independently, refrigerant maldistribution tends to occur.
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. The header includes compartments dedicated to a group of heat exchange tubes which is a subset of the total number of heat exchange tubes. Typically, a distribution tube is located within the header to provide working fluid to the microchannel tubes of the compartments. The distribution tube may have cavities opening in the compartments to provide working fluid to the compartments of the header. Another embodiment of the internal distributor could be a tube with spaced ports on the body of the tube.
However, the problem of mal-distribution becomes exacerbated when the header of the MCHX is in a vertical configuration. 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. Moreover, the maldistribution phenomenon may cause the two-phase (zero superheat) conditions at the exit of some tubes, promoting potential flooding of the compressor suction that may quickly lead to compressor failure.
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.
Referring to
In one or more embodiments, the inlet header 102 and the outlet header 110 may be configured in a vertical orientation, with the plurality of microchannel tubes 108 extending between the inlet header 102 and the outlet header 110. However, the inlet header 102 and the outlet header 110 may also be horizontal or some intermediate angle between vertical and horizontal.
In one or more embodiments, the heat exchanger 100 can include an external fluid distributor 200 (also referred to as first distributor, herein) comprising an inlet port 202 and a plurality of outlet ports 204 (shown in
In one or more embodiments, the first distributor 200 can include a housing of a shape that can include the inlet port 202 at a first end of the housing and the plurality of outlet ports at a second end of the housing. Further, the inlet port 202 can be in fluidic communication with the plurality of outlet ports 204 via a plurality of fluidic passages extending within the housing. In one or more embodiments, the outlet ports 204 of the first distributor 200 can be non-uniform in size such that different volume of fluid can be provided in different first compartments 104 of the inlet header 102. This may overcome the effect of air flow maldistribution on the heat exchanger involving a fan, where the location of the fan or orientation of the fan with respect to the heat exchanger may cause the air flow maldistribution. Referring to
Referring to
It should be obvious to a person skilled in the art that while various embodiments of this subject disclosure have been elaborated for the first distributor 200 having a conical shape or shower-head type construction, however, the teachings of this subject disclosure are equally applicable for the first distributor 200 having a different shape or types as far as the outlet ports of the first distributor 200 are connected to each first compartment of the inlet header via the feeder pipes to supply an equal volume of the fluid comprising of liquid-vapor mixture from the expansion valve into the first compartments, and all such embodiments are well within the scope of this subject disclosure.
In one or more embodiments, the feeder pipe 206 associated with each of the first compartment 104 can be connected to the bottom end of the corresponding first compartment 104 to prevent accumulation of the fluid or creation of standing column of the fluid within the first compartments 104 of the header 102 and further facilitate even distribution of the fluid into the tubes 108, however, the feeder pipe 206 associated with each of the first compartment 104 may also be connected to a middle end or an upper end or other position in the corresponding first compartment 104 as long as the standing column of the fluid is not created in the compartments of the inlet header 102.
Accordingly, the fluid (two-phase refrigerant) supplied by the expansion valve EV can be received by the first distributor 200 at the inlet port 202 and the outlet ports 204 can further meter an equal or predetermined volume of the fluid into each of the first compartments 104 of the inlet header 102. In addition, the smaller volume of the first compartments 104 (compared to an inlet header of the same size and without any partition walls) can allow the fluid (received from the first distributor 200 via the feeder pipes 206) to be uniformly mixed and evenly distributed into the ports of the microchannel tubes 108 associated with the corresponding compartment 104. Additionally, an internal flow mixer or distribution device can be present. Thus, the heat exchanger 100 can achieve a more uniform distribution of the fluid across all the microchannel tubes 108, thereby enhancing the overall thermal performance of the heat exchanger 100.
In one or more embodiments, the outlet header 110 can also include one or more hollow compartments 112-1 to 112-N (collectively designated as second compartments 112, herein) separated by one or more second walls 114-1 to 114-N (collectively referred to as second walls or partition walls 114, herein). The inlet header 102 and the outlet header 110 can be hollow members having parallelly placed walls separated by a predefined distance to create the compartments therewithin. In one or more embodiments, the inlet header 102 and the outlet header 110 may have a cylindrical profile or a substantially curved profile with flat bases at the two opposite ends but is not limited to the like. Referring to
In one or more embodiments, the first compartments 104 and/or the second compartments 112 may have equal volumes or the volumes may vary. When the compartment volumes vary the number of microchannel tubes 108 associated with the corresponding compartments 104, 112 may vary as well. In one or more embodiments, the heat exchange section can include a plurality of refrigerant circuits 108-A to 108-N, where each circuit 108-A to 108-N can include a group of microchannel tubes 108 that can be a subset of a total number of the plurality of microchannel tubes 108 based on the volume of the corresponding compartment 104. Further, the group of microchannel tubes associated with each refrigerant circuit 108-A to 108-N can include a predefined number of passes and a predefined number of turns.
In one or more embodiments, in a single-pass configuration, the outlet header 110 may not have any partition walls. Further, a first end of the group of microchannel tubes 108 associated with each of the circuits can be fluidically connected to one of the first compartments 104 of the inlet header 102, and a second end of the corresponding group of microchannel tubes 108 associated with each of the circuits can be fluidically connected to the outlet header 110.
In one or more embodiments, in a multi-pass configuration, the outlet header 110 can include the second compartments 112. Further, a first end of the group of microchannel tubes 108 associated with each of the circuits can be fluidically connected to one of the first compartments 104 of the inlet header 102, and a second end of the corresponding group of microchannel tubes 108 associated with each of the circuits can be fluidically connected to one of the second compartments 112 of the outlet header 110. Furthermore, the group of microchannel tubes 108 associated with each of the circuits can include the predefined number of passes and the predefined number of turns.
In one or more embodiments, when the heat exchanger 100 is configured as an evaporator, the number of the microchannel tubes 108 in a subsequent pass among the predefined number of passes can be greater than the number of the microchannel tubes 108 in a corresponding preceding pass. In an example, as shown in
In one or more embodiments, when the heat exchanger 100 is configured as a condenser, the number of the microchannel tubes 108 in a subsequent pass among the predefined number of passes can be less than the number of the microchannel tubes 108 in a corresponding preceding pass. In an example, as shown in
In one or more embodiments, (not shown) each of the passes associated with the circuits can be fluidically connected by a flow-mixing device or an internal flow distribution device. An outlet end of the tubes 108 associated with a preceding pass can be connected to inlet(s) of the flow-mixing device and an inlet end of the tubes 108 associated with a subsequent pass can be connected to outlets of the flow-mixing device. Further, in one or more embodiments, the flow mixing device(s) can be disposed of in each of the second compartments 112 associated with the outlet header 110, however, the flow mixing device(s) can also remain outside of the outlet header 110.
Referring to
In one or more embodiments, the second distributor of the inlet header 102 can include a plurality of distribution tubes extending longitudinally through the inlet header 102, such that each of the distribution tubes extends up to and remains fluidically connected to one of the first compartments 104-1 to 104-N, thereby fluidically connecting the expansion valve (EV) to each of the first compartments 104-1 to 104-N of the inlet header 102. Accordingly, each of the distribution tubes can act as an internal fluid distributor for one of the first compartments 104 of the inlet header 102, which can receive fluid from the expansion valve (EV) and supply the fluid into the respective first compartments 104 and further evenly distribute the fluid into the microchannel tubes associated with the corresponding first compartment 104.
Referring to
It should be obvious to a person skilled in the art that while various embodiments of this subject disclosure have been elaborated for the headers having a specific number of compartments and the refrigerant circuits having a specific configuration and number of passes for the sake of simplicity and better explanation purpose, however, the teachings of this subject disclosure are equally applicable for the headers having a different number of compartments and the refrigerant circuits having a different number of passes and configuration, and all such embodiments are well within the scope of this subject disclosure.
Thus, this invention overcomes the drawbacks, limitations, and shortcomings associated with existing heat exchangers and corresponding fluid distributors by providing an improved, effective, and compact solution that helps the heat exchanger supply an equal volume of the fluid into the compartments of the inlet header and further helps achieve a more uniform distribution of the fluid phases across all the microchannel tubes, thereby enhancing the overall thermal performance of the heat exchanger.
While the subject disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the subject disclosure as defined by the appended claims. Modifications may be made to adopt a particular situation or material to the teachings of the subject disclosure without departing from the scope thereof. Therefore, it is intended that the subject disclosure not be limited to the particular embodiment disclosed, but that the subject disclosure includes all embodiments falling within the scope of the subject disclosure as defined by the appended claims.
In interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
Without excluding further possible embodiments, certain example embodiments are summarized in the following clauses:
Clause 1: A heat exchanger comprising: an inlet header that comprises first compartments separated by first walls; a plurality of microchannel tubes extending between and in fluidic connection with the first compartments and an outlet header of the heat exchanger; and a first distributor comprising an inlet port and a plurality of outlet ports, wherein a plurality of feeder pipes is configured between the first compartments of the inlet header and the outlet ports of the first distributor, such that each of the first compartments remains fluidically connected to one of the outlet ports of the first distributor by one of the feeder pipes to allow flow of an equal volume of fluid from the first distributor into each of the first compartments; and a second distributor configured within the first compartments, the second distributor configured to mix and allow uniform flow of fluid into the microchannel tubes of each of the first compartments.
Clause 2: The heat exchanger of clause 1, wherein the inlet header and/or the outlet header comprises one or more orifice plates configured coaxially within the corresponding compartments.
Clause 3: The heat exchanger of clause 1, wherein the heat exchanger comprises a plurality of heat-dissipating fins in thermal contact with the plurality of microchannel tubes.
Clause 4: The heat exchanger of clause 1, wherein the heat exchanger is associated with one or more of a heating, ventilation, air-conditioning, and cooling (HVAC) system, and a transport refrigeration unit.
Clause 5: A fluid distributor for a header comprising compartments separated by walls, the fluid distributor comprising: a housing of a predefined shape that comprises an inlet port, and a plurality of outlet ports in fluidic communication with the inlet port via a plurality of fluidic passages extending within the housing; and a plurality of feeder pipes, wherein a first end of the feeder pipe is fluidically connected to one of the outlet ports of the housing, wherein a second end of the corresponding feeder pipe is configured to be fluidically connected to one of the compartments of the header to allow flow of an equal volume of fluid from the distributor into each of the compartments.
Clause 6: The fluid distributor of clause 5, wherein the housing has a solid conical shape that comprises a substantially circular base, and a curved lateral surface extending from a vortex end of the distributor to the circular base, wherein the housing comprises the inlet port at the vortex end, and the plurality of outlet ports being configured circumferentially around the circular base and in fluidic communication with the inlet port via the plurality of fluidic passages.
This patent application claims the benefit of U.S. Provisional Patent Application No. 63/593,324, filed on Oct. 26, 2023, which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63593324 | Oct 2023 | US |
