MICROCHANNEL HYBRID EVAPORATOR
A heat exchanger including a primary inlet manifold that has an inlet port to receive refrigerant from a source, a primary outlet manifold that has an outlet port to discharge refrigerant from the heat exchanger, and a plurality of microchannel tubes fluidly connected between the primary inlet manifold and the primary outlet manifold and spaced apart from each other. Each of the plurality of microchannel tubes has a secondary inlet manifold fluidly coupled to the primary inlet manifold, a secondary outlet manifold fluidly coupled to the primary outlet manifold, and at least one microchannel fluidly coupled between the secondary inlet manifold and the secondary outlet manifold to direct refrigerant to the secondary outlet manifold. The heat exchanger also includes a plurality of fins disposed between adjacent microchannel tubes and oriented to define an airflow path along the longitudinal direction of the microchannel tubes.
This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61/486,521 filed May 16, 2011, the entire contents of which are hereby incorporated by reference.
BACKGROUNDThe present invention relates to an evaporator, and more particularly to a microchannel evaporator.
In conventional practice, many refrigeration circuits utilize an evaporator including a coil that is formed from round copper or aluminum tubing. Other refrigeration circuits utilize an evaporator that includes a coil with microchannel tubes and fins in very high densities that can only operate at refrigerant temperatures above 32 degrees Fahrenheit due to rapid ice buildup in the fins at temperatures below 32 degrees Fahrenheit.
SUMMARYThe invention provides a heat exchanger that includes microchannel tubes and fins for use in low (e.g., −20 degrees Fahrenheit) and medium-temperature (e.g., 26 degrees Fahrenheit) refrigeration applications. The evaporator can achieve a discharge air temperature that is as close as possible to the temperature of the refrigerant inside the coil, which allows for higher refrigerant temperatures in the coil to be used, which saves energy. The evaporator can reduce the refrigerant charge of the system by using microchannel ports inside of the coil rather than traditional round copper or aluminum tubes. The evaporator can be modular or full length such that it is the same nominal length as a merchandiser. The evaporator can vary in depth, height, and width. Refrigerant may enter and exit on the same side of the coil, on opposite sides of the coil, or somewhere in between the ends of the larger manifolds. Sandwiched between the microchannel tubes are fins which can vary in density from one to ten fins per inch depending upon the temperature application. The fins can have a variety of shapes (e.g., triangular, offset strips, wavy, louvered, perforated, etc.). Fin density in the evaporator can be the same or varied in different areas of the evaporator. Fin density can be varied along the coil such that a lower fin density can be used at the air inlet side of the coil to remove moisture from an air flow. As more moisture is removed from the air passing through the coil, higher fin densities can be used, especially near the outlet. For low temperature applications fin density can be decreased as needed to accommodate buildup of frost.
In one construction, the invention provides a heat exchanger including a primary inlet manifold that has an inlet port to receive refrigerant from a source, a primary outlet manifold that has an outlet port to discharge refrigerant from the heat exchanger, and a plurality of microchannel tubes fluidly connected between the primary inlet manifold and the primary outlet manifold and spaced apart from each other. Each of the plurality of microchannel tubes has a secondary inlet manifold fluidly coupled to the primary inlet manifold, a secondary outlet manifold fluidly coupled to the primary outlet manifold, and at least one microchannel fluidly coupled between the secondary inlet manifold and the secondary outlet manifold to direct refrigerant to the secondary outlet manifold. The heat exchanger also includes a plurality of fins disposed between adjacent microchannel tubes and oriented to define an airflow path along the longitudinal direction of the microchannel tubes.
In another construction, the invention provides a heat exchanger including an inlet manifold that has an inlet port to receive refrigerant from a source, an outlet manifold that has an outlet port to discharge refrigerant from the heat exchanger, and a plurality of refrigerant tubes fluidly connected between the inlet manifold and the outlet manifold and spaced apart from each other. Each of the plurality of microchannel tubes has a plurality of microchannels. The heat exchanger also includes a plurality of fins positioned between adjacent microchannel tubes and having an airflow inlet oriented to receive an airflow and an airflow outlet, the fins defining a fin density that varies along the length of the refrigerant tubes based on the location of the fins relative to the airflow inlet and the airflow outlet.
In another construction, the invention provides a heat exchanger including a primary inlet manifold that has an inlet port to receive refrigerant from a source, a primary outlet manifold that has an outlet port to discharge refrigerant from the heat exchanger, and a plurality of microchannel tubes fluidly connected between the primary inlet manifold and the primary outlet manifold and spaced apart from each other. Each of the plurality of microchannel tubes has a secondary inlet manifold fluidly coupled to the primary inlet manifold, a secondary outlet manifold fluidly coupled to the primary outlet manifold, and a plurality of microchannels fluidly coupled between the secondary inlet manifold and the secondary outlet manifold to direct refrigerant to the secondary outlet manifold. The heat exchanger also includes a plurality of fins disposed between adjacent microchannel tubes. The fins have an airflow inlet oriented to receive an airflow and an airflow outlet, and define a first fin portion that has a first fin density and a second fin portion that has a second fin density such that the density of the fins varies along the length of the refrigerant tubes based on the location of the fins relative to the airflow inlet and the airflow outlet.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
DETAILED DESCRIPTIONAs shown in
The flat tubes 45 can be spaced at different or varying distances relative to each other to maximize performance of the evaporator 10 at low and medium temperatures. As illustrated in
As illustrated in
The fins 55 vary in density along the length of the flat tube 45. With reference to
With reference to
In operation, the evaporator 10, 110, 210 functions as part of a two-phase refrigeration system in which the evaporator 10, 110, 210 receives low-pressure, low-temperature liquid refrigerant, removes heat from an airflow (e.g., airflow 60, 145) that passes through the evaporator 10, 110, 210, and discharges gaseous refrigerant to one or more compressors (not shown). The low-pressure, low-temperature liquid refrigerant evaporates as it passes through the evaporator 10, 110, 210 such that the refrigerant passes through a substantial portion of the evaporator 10, 110, 210 as a two-phase mixture (i.e., a liquid-gas state).
With reference to the evaporator 10, for example, the inlet port 20 directs low-pressure, low-temperature liquid refrigerant into the primary inlet manifold 15, which provides refrigerant to the plurality of second inlet manifolds 35. The second inlet manifolds 35 direct refrigerant to the plurality of flat tubes 45 where the refrigerant is then directed through the microchannels 50. The refrigerant flows from the microchannels 50 to the plurality of secondary outlet manifolds 40, and then to the primary outlet manifold 25 before reaching the outlet port 30.
The evaporator 10, 110, 210 achieves a discharge air temperature that is as close as possible to the temperature of the refrigerant inside the coil. The similarity in temperatures between the refrigerant and the air flowing through the evaporator 10, 110, 210 results in higher refrigerant temperatures in the coil, which reduces energy costs because it is more likely that the refrigerant directed to the compressors will be in a gaseous state. The microchannels 50, 215 minimize the refrigerant charge of the refrigeration system as compared to conventional evaporators with round copper or aluminum tubes. The evaporator 10, 110, 210 can be modular or full length, and the size (e.g., depth, height, or width) can vary depending on the size and type of merchandiser in which the evaporator 10, 110, 210 will be used.
The evaporator 10, 110, 210 accommodates multiple or variable fin densities and microchannel tube spacing to maximize performance of the evaporator 10, 110, 210 based on the temperature application in which the evaporator 10, 110, 210 will be used. For example, the fin density can be varied in the evaporator 10, 110, 210 so that a low fin density (e.g., third density fin portion 75) is oriented at the air inlet side of the evaporator 10, 110, 210 to remove moisture from an air flow to minimize frosting of the evaporator 10, 110, 210. As moisture is removed from the air passing through the evaporator 10, 110, 210, higher fin densities (e.g., first density fin portion 65, second density fin portion 70) can be oriented adjacent the middle and outlet-side of the evaporator 10, 110, 210. In low temperature applications, the fin density of the evaporator 10, 110, 210 can be further decreased relative to medium temperature applications to minimize frost buildup.
The primary inlet manifold 15, 115 distributes refrigerant to the microchannels 50, 215 so that the latent heat absorbed by the refrigerant is as high as possible without frosting the evaporator 10, 110, 210. With regard to the evaporator 10, for example, the plurality of secondary inlet manifolds 35 evenly distribute refrigerant from primary inlet manifold 15 to the microchannels 50. Similarly, the plurality of secondary outlet manifolds evenly distribute heated refrigerant from the microchannels 50 to the primary outlet manifold 35.
Various features and advantages of the invention are set forth in the following claims.
Claims
1. A heat exchanger comprising:
- a primary inlet manifold including an inlet port to receive refrigerant from a source;
- a primary outlet manifold including an outlet port to discharge refrigerant from the primary outlet manifold;
- a plurality of microchannel tubes fluidly connected between the primary inlet manifold and the primary outlet manifold and spaced apart from each other, each of the plurality of microchannel tubes including a secondary inlet manifold fluidly coupled to the primary inlet manifold, a secondary outlet manifold fluidly coupled to the primary outlet manifold, and at least one microchannel fluidly coupled between the secondary inlet manifold and the secondary outlet manifold to direct refrigerant to the secondary outlet manifold; and
- a plurality of fins disposed between adjacent microchannel tubes and oriented to define an airflow path along the longitudinal direction of the microchannel tubes.
2. The heat exchanger of claim 1, wherein the plurality of microchannel tubes are spaced apart from each other along the length of the primary inlet manifold.
3. The heat exchanger of claim 1, wherein the microchannel tubes extend substantially vertically and the fins are oriented such that an airflow is directed in a generally vertical direction along the airflow path.
4. The heat exchanger of claim 1, wherein the fins have one of a rectangular cross-sectional shape, a triangular cross-sectional shape, a curved cross-sectional shape.
5. The heat exchanger of claim 4, wherein the fins define a fin density that varies along the length of each of the microchannel tubes.
6. The heat exchanger of claim 1, wherein the fins have one of a wavy profile, a louvered profile, and a perforated profile.
7. The heat exchanger of claim 1, wherein the primary inlet manifold and the primary outlet manifold are oriented substantially horizontal, and wherein the secondary inlet manifold is oriented at a non-zero angle relative to the primary inlet manifold and the secondary outlet manifold is oriented at a non-zero angle relative to the primary outlet manifold.
8. A heat exchanger comprising:
- an inlet manifold including an inlet port to receive refrigerant from a source;
- an outlet manifold including an outlet port to discharge refrigerant from the primary outlet manifold;
- a plurality of refrigerant tubes fluidly connected between the inlet manifold and the outlet manifold and spaced apart from each other, each of the plurality of microchannel tubes including a plurality of micro channels; and
- a plurality of fins positioned between adjacent microchannel tubes and having an airflow inlet oriented to receive an airflow and an airflow outlet, the fins defining a fin density that varies along the length of the refrigerant tubes based on the location of the fins relative to the airflow inlet and the airflow outlet.
9. The heat exchanger of claim 8, wherein the fin density of the fins located adjacent the airflow inlet is lower than the fin density of the fins located adjacent the airflow outlet.
10. The heat exchanger of claim 9, wherein the fins define a first fin portion having a first fin density and a second fin portion having a second fin density that is lower than the first fin density.
11. The heat exchanger of claim 10, wherein the fins further define a third fin portion having a third fin density that is lower than the second fin density.
12. The heat exchanger of claim 8, wherein the fins are oriented to define an airflow path along the longitudinal direction of the microchannel tubes.
13. The heat exchanger of claim 12, wherein the refrigerant tubes extend substantially vertically and the fins are oriented such that an airflow is directed in a generally vertical direction along the airflow path.
14. The heat exchanger of claim 8, wherein the fins have one of a rectangular cross-sectional shape, a triangular cross-sectional shape, a curved cross-sectional shape, a wavy profile, a louvered profile, and a perforated profile.
15. The heat exchanger of claim 8, wherein the fins are defined by a body portion and end portions on both ends, at least one of the end portions defining one of the airflow inlet and the airflow outlet on a face side of the heat exchanger.
16. The heat exchanger of claim 15, wherein the fins include curved end portions on both ends such that the airflow inlet and the airflow outlet are disposed in at least one face side of the heat exchanger.
17. The heat exchanger of claim 16, wherein each of the body portion and the curved end portions are defined by a substantially rectangular cross-section.
18. The heat exchanger of claim 15, wherein the airflow inlet and the airflow outlet are disposed on the same face side of the heat exchanger.
19. The heat exchanger of claim 18, wherein the airflow inlet and the airflow outlet are defined by a substantially rectangular cross-section.
20. A heat exchanger comprising:
- a primary inlet manifold including an inlet port to receive refrigerant from a source;
- a primary outlet manifold including an outlet port to discharge refrigerant from the primary outlet manifold;
- a plurality of microchannel tubes fluidly connected between the primary inlet manifold and the primary outlet manifold and spaced apart from each other, each of the plurality of microchannel tubes including a secondary inlet manifold fluidly coupled to the primary inlet manifold, a secondary outlet manifold fluidly coupled to the primary outlet manifold, and a plurality of microchannels fluidly coupled between the secondary inlet manifold and the secondary outlet manifold to direct refrigerant to the secondary outlet manifold; and
- a plurality of fins disposed between adjacent microchannel tubes and having an airflow inlet oriented to receive an airflow and an airflow outlet, the fins defining a first fin portion having a first fin density and a second fin portion having a second fin density such that the density of the fins varies along the length of the refrigerant tubes based on the location of the fins relative to the airflow inlet and the airflow outlet.
21. The heat exchanger of claim 20, wherein the first fin portion is disposed adjacent the secondary outlet manifold and the first fin density is higher than the second fin density.
22. The heat exchanger of claim 21, wherein the fins further define a third fin portion disposed adjacent the secondary inlet manifold and has a third fin density that is lower than the second fin density.
23. The heat exchanger of claim 20, wherein the fins are oriented to define an airflow path along the longitudinal direction of the microchannel tubes.
Type: Application
Filed: May 16, 2012
Publication Date: Nov 22, 2012
Inventor: Timothy D. Anderson (St. Louis, MO)
Application Number: 13/472,975
International Classification: F28D 15/00 (20060101);