Technical Field

[0001] Various embodiments generally relate to a microchannel heat exchanger. In particular, various embodiments generally relate to a microchannel heat exchanger with vertical fins.

Background

[0002] Microchannel heat exchanger is a type of fin and tube heat exchanger widely use in various industries for applications such as thermal control, cooling, air conditioning, or refrigeration. However, the performance of such conventional microchannel heat exchanger is generally affected by condensate, such as dew and/or frost, blocking airflow which requires frequent application of a defrosting cycle for removing the condensate so as to maintain its performance.

[0003] Accordingly, there is a need to provide an enhanced and more efficient microchannel heat exchanger that addresses the above problems.

Summary

[0004] According to various embodiments, there may be provided a microchannel heat exchanger. According to various embodiments, the microchannel heat exchanger may include a first elongate manifold having a first longitudinal axis. According to various embodiments, the microchannel heat exchanger may further include a second elongate manifold having a second longitudinal axis. According to various embodiments, the first elongate manifold and the second elongate manifold may be parallel and opposing each other. According to various embodiments, the microchannel heat exchanger may further include a plurality of flat tubes extending between the first elongate manifold and the second elongate manifold. According to various embodiments, each of the plurality of flat tubes may have a longitudinal tube axis perpendicular to the first longitudinal axis of the first elongate manifold and the second longitudinal axis of the second elongate manifold. According to various embodiments, each of the plurality of flat tubes may be oriented with a transverse axis extending between a leading longitudinal edge portion and a trailing longitudinal edge portion thereof forming a non-perpendicular angle with respect to the first longitudinal axis of the first elongate manifold and the second longitudinal axis of the second elongate manifold. According to various embodiments, the microchannel heat exchanger may further include a plurality of vertical fins extending across the plurality of flat tubes and parallel to each other. According to various embodiments, each of the plurality of vertical fins may be parallel to the first longitudinal axis of the first elongate manifold and the second longitudinal axis of the second elongate manifold.

[0005] According to various embodiments, a microchannel heat exchanger system may be provided. The microchannel heat exchanger system may include the microchannel heat exchanger according to various embodiments. According to various embodiments, the microchannel heat exchanger system may further include a fan coupled to the microchannel heat exchanger to generate an airflow across the plurality of flat tubes from the leading longitudinal edge portions to the trailing longitudinal edge portions.

Brief description of the drawings

[0006] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments are described with reference to the following drawings, in which:

FIG. 1 A shows a front schematic view of a microchannel heat exchanger according to various embodiments;

FIG. IB shows a side schematic cross-sectional view of the microchannel heat exchanger taken along A- A;

FIG. 2 shows a microchannel heat exchanger according to various embodiments having a first sub-set of flat tubes and a second sub-set of flat tubes that are respectively arranged based on a hyperbolic airflow pattern; and FIG. 3 shows a microchannel heat exchanger system including a fan according to various embodiments.

Detailed description

[0007] Embodiments described below in the context of the apparatus are analogously valid for the respective methods, and vice versa. Furthermore, it will be understood that the embodiments described below may be combined, for example, a part of one embodiment may be combined with a part of another embodiment.

[0008] It should be understood that the terms “on”, “over”, “top”, “bottom”, “down”, “side”, “back”, “left”, “right”, “front”, “lateral”, “side”, “up”, “down” etc., when used in the following description are used for convenience and to aid understanding of relative positions or directions, and not intended to limit the orientation of any device, or structure or any part of any device or structure. In addition, the singular terms “a”, “an”, and “the” include plural references unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise.

[0009] Various embodiments generally relate to an efficient microchannel heat exchanger with enhanced defrosting (e.g. through the flat tubes and fins) and heating capability. According to various embodiments, the microchannel heat exchanger may include a microchannel flat tubes arrangement that is angled and that utilizes vertical fins to extend frosting time (or time to frosting), reduce air resistance on the surfaces of the microchannel heat exchanger that comes into contact with an airflow, and enable easy defrosting through the flat tubes and fins.

[00010] According to various embodiments, the microchannel heat exchanger may include a fin configuration that is kept vertical for condensed dew (e.g. water droplets) on the fins to drop downwards easily (e.g. by way of the gravitational pull acting on the water droplets). Such fin configuration may prevent the collection of condensed dew as known in v-shaped fins, thus, reducing or minimizing or eliminating the likelihood of the condensed dew turning into frost affecting the heat transfer efficiency or clogging with small particles leading to fouling that may even prevent defrosting. Vertical fin configuration may also reduce the size of the fin in the microchannel heat exchanger. According to various embodiments, the microchannel heat exchanger may further include flat tubes which may be angled (or rotated) at an angle that improves the hydrophobicity of the flat tubes surfaces to enable condensed dew to flow off easily. The angled arrangement may also reduce or minimize or eliminate the likelihood of the condensed dew being trapped by the generally rough surface of the flat tubes due to residuals of clad, brazing materials etc. from the manufacturing processes as compared to a horizontal arrangement of the flat tubes. Accordingly, the microchannel heat exchanger may include microchannel flat tubes that are positioned at an optimum angle for enhancing hydrophobic capability of an upper surface of the flat tubes. Accordingly, the microchannel heat exchanger according to various embodiments may enable removal of condensed dew water or water droplets collected or formed on the microchannel heat exchanger.

[00011] According to various embodiments, the microchannel heat exchanger may include a first set of upper flat tubes on an upper half of the microchannel heat exchanger and a second set of lower flat tubes on a lower half of the microchannel heat exchanger which are respectively parallel to a corresponding upper half and lower half of an actual fan airflow pattern. The upper flat tubes on the upper half of the microchannel heat exchanger may be angled (or rotated) in a counter-clockwise arrangement (e.g. when looking from a one longitudinal end of the microchannel heat exchanger) so as to be parallel to the corresponding upper half of the actual fan airflow pattern, whereas the lower flat tubes on the lower half of the microchannel heat exchanger may be angled (or rotated) in a clockwise arrangement (e.g. when looking from the aforementioned one longitudinal end of the microchannel heat exchanger) so as to be parallel to the corresponding lower half of the actual fan airflow pattern. It is found that the actual airflow pattern within the microchannel heat exchanger may include a hyperbolical pattern within the microchannel heat exchanger directly coupled to a fan in series. Thus, in the case of a microchannel heat exchanger which has flat tubes, the airflow has a pressure drop effect as a result of the flat tubes configuration. [00012] The microchannel heat exchanger according to various embodiments may differ from conventional microchannel heat exchangers in that the flat tubes assembly may be arranged in a predetermined order (or orientation or configuration), in particular, the angles of each flat tube may be determined based on an actual airflow pattern across the microchannel heat exchanger. These features may enable the microchannel heat exchanger according to various embodiments to utilize the airflow across it more effectively. Furthermore, with the flat tubes assembly being angled, hydrophobic angle of the flat tubes surfaces may be improved, thereby enabling easy disposal of dewing water despite a surface roughness of the flat tubes and the fins of the microchannel heat exchanger according to various embodiments remaining the same as those manufactured using conventional means. [00013] Thus, in changing the respective angles of the flat tubes of the flat tubes assembly based on airflow direction (e.g. of an airflow generated by the fan), air resistance on the microchannel heat exchanger surfaces may be reduced. A uniform airflow that is parallel with the upper and lower surfaces of the flat tubes may also improve heat transfer between the flat tubes and the surrounding air. Accordingly, the enhanced features of the flat tubes assembly angled based on fan airflow direction may enable better heat transfer along the flat tubes as well as facilitate disposal of dewing water (e.g. formed on the microchannel heat exchanger from a defrost operation). Accordingly, despite water formation on the flat tubes and fins of the microchannel heat exchanger according to various embodiments being similar to that occurring with conventional microchannel heat exchangers, nevertheless, water disposal capability of the microchannel heat exchanger according to various embodiments may be better than conventional microchannel heat exchangers.

[00014] According to various embodiments, the microchannel heat exchanger may have a reduced horizontal fin length (or width) by up to 30% less compared to the fins of conventional microchannel heat exchanger. In other words, the microchannel heat exchanger according to various embodiments may reduce a long horizontal fin length (or width) by 30% less. This may be a result of the angled flat tubes having better capability at water disposal vertically (or along a substantially vertical direction) compared to conventional microchannel heat exchangers and/or may be due to decreased occurrence (or decreased tendency) for frosting to occur on the microchannel heat exchanger according to various embodiments. With reduced fin size, less material may be required to manufacture the fins of the microchannel heat exchanger according to various embodiments, in turn, decreasing the cost of the microchannel heat exchanger. Furthermore, the reduced fin size may be advantageous in resulting in less airflow resistance against the surface of the fins of the microchannel heat exchanger according to various embodiments.

[00015] According to various embodiments, the microchannel heat exchanger may include distributors with tube inlet slots that may be angled (e.g. of the same angle as the flat tubes) for better fluid (e.g. refrigerant) distribution and avoiding mal-distribution. According to various embodiments, the angled tube inlet slots may result in better homogeneous flow as the angle approaches vertical. [00016] Accordingly, a microchannel heat exchanger may be provided with features that may enable water (e.g. condensed dew) to be easily removed from the microchannel heat exchanger and that provide the microchannel heat exchanger with enhanced heat transfer properties. The microchannel heat exchanger may be provided with (i) a flat tubes assembly arranged in the predetermined order (or orientation or configuration) and angle, (ii) specially configured distributor headers, and (iii) a plurality of vertical fins (or a fin configuration) with optimized (e.g. reduced) fin size.

[00017] The microchannel heat exchanger may be produced and applied (e.g. retrofitted) to any air-powered heat pump outdoor units. Conducting defrost test conditions may be sufficient to evaluate whether the microchannel heat exchanger may work effectively to improve defrosting. Further evaluation criteria which may be used to determine whether the microchannel heat exchanger may work effectively with an existing heat pump outdoor unit may be: frosting and defrosting time, heating capacity and/or COP (heating operation performance) etc. When the microchannel heat exchanger is retrofitted to an air-powered heat pump outdoor unit, high fan suction power of the unit may not be required for removal of condensed dew or any water droplets (e.g. formed after a defrost operation) away from the microchannel heat exchanger.

[00018] The microchannel heat exchanger according to various embodiments may be easy to manufacture. For example, existing manufacturing processes for manufacturing conventional microchannel heat exchangers may be used with simple changes to those processes such as having a new fin press die and making modifications to the distributors (e.g. headers).

[00019] FIG. 1A shows a front schematic view of a microchannel heat exchanger 100 according to various embodiments. FIG. IB shows a side schematic cross-sectional view of the microchannel heat exchanger 100 taken along A- A.

[00020] According to various embodiments, the microchannel heat exchanger 100 may include a first elongate manifold 102 (or distributor, e.g. header) having a first longitudinal axis 103. The microchannel heat exchanger 100 may further include a second elongate manifold 202 having a second longitudinal axis 203. According to various embodiments, the first elongate manifold 102 and the second elongate manifold 202 may be parallel and opposing each other. Accordingly, the first elongate manifold 102 and the second elongate manifold 202 may be orientated with the respective first longitudinal axis 103 and second longitudinal axis 203 being parallel to each other. Each of the first elongate manifold 102 and the second elongate manifold 202 may be hollow for fluid flow therethrough. According to various embodiments, the first elongate manifold 102 and the second elongate manifold 202 may be configured to distribute or circulate a fluid to a plurality of flat tubes 301 between the first elongate manifold 102 and the second elongate manifold 202.

[00021] According to various embodiments, the microchannel heat exchanger 100 may further include the plurality of flat tubes 301. As shown, the plurality of flat tubes 301 may extend between the first elongate manifold 102 and the second elongate manifold 202. The plurality of flat tubes 301 may be extending perpendicularly (or substantially perpendicularly) with respect to the first elongate manifold 102 and the second elongate manifold 202. Accordingly, each of the plurality of flat tubes 301 may have a longitudinal tube axis 302 that is perpendicular (or substantially perpendicular) to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202.

[00022] According to various embodiments, each of the plurality of flat tubes 301 may include a plurality of micro-channels 310 (or micro-ports) (see FIG. IB) for fluid flow therethrough, between a substantially flat outer base surface 303 and a substantially flat outer upper surface 304 opposite the outer base surface 303 of the flat tube 301. As shown, the micro-channels 310 may be arranged alongside each other in a side-by-side manner to form a straight cross-sectional profile across the micro-channels 310. According to various embodiments, the plurality of flat tubes 301 may be in fluidic connection with the first elongate manifold 102 and the second elongate manifold 202. Accordingly, a fluid (e.g. refrigerant) may flow or circulate between the first elongate manifold 102 and the second elongate manifold 202 via the respective micro-channels 310 of the plurality of flat tubes 301.

[00023] According to various embodiments, a fluid inlet port and a fluid outlet port (not shown) may be provided on any one of the first elongate manifold 102 or the second elongate manifold 202 for, respectively, providing fluid to the microchannel heat exchanger 100 and for directing fluid away from the microchannel heat exchanger 100. According to various embodiments, each of the first elongate manifold 102 and the second elongate manifold 202 may be vertical (e.g. upright) and may be configured with angled slots for receiving the angled flat tubes 301 to reduce or avoid mal-distribution of fluid to the flat tubes 301.

[00024] As shown in FIG. IB, according to various embodiments, the plurality of flat tubes 301 may be in a louvred arrangement, whereby each of the plurality of flat tubes 301 may be angled in a non-horizontal manner. Accordingly, each of the plurality of flat tubes 301 may be positioned or oriented in a transversely incline or slant manner with respect to a horizontal plane of the microchannel heat exchanger 100 that is perpendicular to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202. Accordingly, respective outer base surface 303 and outer upper surface 304 of each flat tube 301 of the plurality of flat tubes 301 may be inclined or slanted sideways with respect to the horizontal plane. According to various embodiments, each of the plurality of flat tubes 301 may be oriented with a transverse axis 305 extending between a leading longitudinal edge portion 306 and a trailing longitudinal edge portion 307 thereof forming a non-perpendicular angle (i.e. reference 900 in FIG. IB) with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202. The transverse axis 305 of each of the plurality of flat tubes 301 may be extending directly across the respective outer base surface 303 and/or outer upper surface 304 from the leading longitudinal edge portion 306 of the respective flat tube 301 to the trailing longitudinal edge portion 307 of the respective flat tube, or vice versa. Each of the plurality of flat tubes 301 may be angled or oriented or positioned relative to the first and second elongate manifolds 102, 202 with the transverse axis 305 of each of the plurality of flat tubes 301 forming the non-perpendicular angle (i.e. reference 900 in FIG. IB) with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202.

[00025] According to various embodiments, a magnitude of the non-perpendicular angle (i.e. reference 900) may be less than 90° or more than 90°. According to various embodiments the magnitude of the non-perpendicular angle (i.e. reference 900) may be within a range of 3° to 86°, or 5° to 85°, or 10° to 80°, or 20° to 70°, or 50° to 70°, or 55° to 65°, or 59° to 62°, or 100° to 180°, or 110° to 170°, or 110° to 130°, or 115° to 125°, or 118° to 121°, etc.

[00026] According to various embodiments, all of the plurality of flat tubes 301 may be angled at a same non-perpendicular angle (i.e. reference 900) with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202. In other words, the magnitudes of the nonperpendicular angles (i.e. reference 900) of the transverse axes 305 of all of the plurality of flat tubes 301 with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202 may be the same.

[00027] According to various embodiments, the non-perpendicular angle (i.e. reference 900) of the transverse axis 305 of each of the plurality of flat tubes 301 with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202 may be determined based on a predetermined airflow pattern 700 (e.g. a hyperbolic airflow pattern 710 as shown in FIG. 2 & FIG. 3). The predetermined airflow pattern 700 may be an overall pattern of airflow through the entire microchannel heat exchanger 100. For instance, according to various embodiments, the nonperpendicular angle (i.e. reference 900 in FIG. IB) of the transverse axis 305 of each of the plurality of flat tubes 301 with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202 may be parallel to a local airflow of the predetermined airflow pattern 700 respectively passing across said flat tube 301. The local airflow may be part of the predetermined airflow pattern 700 directly across each of the plurality of flat tubes 301.

[00028] According to various embodiments, the microchannel heat exchanger 100 may further include a plurality of vertical fins 400 extending across the plurality of flat tubes 301. Each of the plurality of vertical fins 400 may be parallel to each other and may further be parallel to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202. Accordingly, each of the plurality of vertical fins 400 may be perpendicular to the plurality of flat tubes 301. Hence, each of the plurality of vertical fins 400 may be stretched across the plurality of flat tubes 301 to vertically interconnect the louvered flat tubes 301.

[00029] According to various embodiments, each fin 400 of the plurality of vertical fins 400 may include a plate-like structure 401. The plate-like structure 401 may include an elongate vertical section 402 (e.g. fin extension) extending across the leading longitudinal edge portions 306 (e.g. windward side) of the plurality of flat tubes 301. The elongate vertical section 402 may extend in a crosswise manner with respect to the plurality of flat tubes 301 and straddle across the leading longitudinal edge portions 306 of each of the plurality of flat tubes 301. The plate-like structure 401 may further include a plurality of fin- appendages 403 extending laterally from a first longitudinal side 404 of the elongate vertical section 402. Accordingly, the plurality of fin-appendages 403 and the elongate vertical section 402 may form a comb-like structure. According to various embodiments, each of the plurality of fin-appendages 403 may be disposed or slotted between two adjacent flat tubes 301 of the plurality of flat tubes 301 to inter-connect the two adjacent flat tubes 301. Further, each of the plurality of fin-appendages 403 may extend from the leading longitudinal edge portions 306 of the two adjacent flat tubes 301 to the trailing longitudinal edge portions 307 of the two adjacent flat tubes 301. Accordingly, a free-end tip 405 of each of the plurality of fin-appendages 403 may terminate at the trailing longitudinal edge portions 307 of the two adjacent flat tubes 301.

[00030] With reference to FIG. IB, according to various embodiments, a width 406 of the elongate vertical section 402 of each fin 400 of the plurality of vertical fins 400 may be between 15% to 20% of an overall direct width 407 (or the horizontal fin length) of said fin 400 measured from free-end tips 405 of the plurality of fin-appendages 403 to a second longitudinal side 409 of the elongate vertical section 402. According to various embodiments, the width 406 of the elongate vertical section 402 of each fin 400 may be within a range of 3 to 5 mm. According to various embodiments, the overall direct width 407 of said fin 400 may be within a range of 20 to 27 mm. According to various embodiments, a width 408 of said fin 400 measured from free-end tips 405 of the plurality of fin-appendages 403 to the first longitudinal side 404 may be within a range of 17 to 22 mm.

[00031] FIG. 2 shows a microchannel heat exchanger 200 according to various embodiments having a first sub-set 320 of flat tubes 301 and a second sub-set 330 of flat tubes 301 that are respectively arranged based on a hyperbolic airflow pattern 710.

[00032] According to various embodiments, the predetermined airflow pattern 700 across the microchannel heat exchanger 200 may include the hyperbolic airflow pattern 710 through the microchannel heat exchanger 200.

[00033] According to various embodiments, the microchannel heat exchanger 200 may include similar features as the microchannel heat exchanger 100 except that the plurality of flat tubes 301 of the microchannel heat exchanger 200 includes the first sub-set 320 of flat tubes 301 and the second sub-set 330 of flat tubes 301 which are respectively arranged (or inclined or slanted) based on the hyperbolic airflow pattern 710 (or directions of respective air steams of the hyperbolic airflow pattern 710 that come into contact with each flat tube 301). According to various embodiments, the first sub-set 320 of flat tubes 301 may include one or more than one (e.g. two or more) flat tubes 301 and the second sub-set 330 of flat tubes 301 may include one or more than one flat tubes 301. For example, as shown in FIG. 2, the first sub-set 320 of flat tubes 301 may include four flat tubes 301 and the second subset 330 of flat tubes 301 may include four flat tubes 301.

[00034] According to various embodiments, the transverse axis 305 of each of the first sub-set 320 of flat tubes 301 may form a first non-perpendicular angle (i.e. reference 910) with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202. Further, the transverse axis 305 of each of the second sub-set 330 of flat tubes 301 may form a second nonperpendicular angle (i.e. reference 920) with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202. According to various embodiments, the second non-perpendicular angle (i.e. reference 920) may be 180° minus the first non-perpendicular angle (i.e. reference 910) with respect to the first longitudinal axis 103 of the first elongate manifold 102 and the second longitudinal axis 203 of the second elongate manifold 202. Accordingly, the first sub-set 320 of flat tubes 301 and the second sub-set 330 of flat tubes 301 may be respectively inclined or slanted with corresponding trailing longitudinal edge portions 307 thereof close towards each other.

[00035] According to various embodiments, a line of symmetry 111 (see FIG. 1 A) may pass through a middle of the first elongate manifold 102, between a first half 112 (e.g. upper half) and a second half 113 (e.g. lower half) of the first elongate manifold 102, and pass through a middle of the second elongate manifold 202, between a first half 112 (e.g. upper half) and a second half 113 (e.g. lower half) of the second elongate manifold 202. The line of symmetry 111 may be along a frontal plane of the microchannel heat exchanger 100, 200. According to various embodiments, the first sub-set 320 of flat tubes 301 of the microchannel heat exchanger 200 may be extending between the first half 112 of the first elongate manifold 102 and the first half 112 of the second elongate manifold 202 and the second sub-set 330 of the flat tubes 301 of the microchannel heat exchanger 200 may be extending between the second half 113 of the first elongate manifold 102 and a second half 113 of the second elongate manifold 202 in a manner such that the first sub-set 320 of flat tubes 301 and the second sub-set 330 of the flat tubes 301 may be symmetrical about the line of symmetry 111 passing through the middle of the first elongate manifold 102 and the middle of the second elongate manifold 202. Accordingly, in the microchannel heat exchanger 200, the first sub-set 320 of flat tubes 301 may be a mirror image of the second sub-set 330 of flat tubes 301 about the line of symmetry 111.

[00036] FIG. 3 shows a microchannel heat exchanger system 300 including a fan 720 according to various embodiments.

[00037] The system 300 may include any one of the microchannel heat exchanger 100, 200, as described above, according to various embodiments. For ease of understanding, the system 300 of FIG. 3 will be described with reference to microchannel heat exchanger 200. Nevertheless, the system 300 may alternatively include microchannel heat exchanger 100 instead of microchannel heat exchanger 200 or may include a microchannel heat exchanging having any or a combination of the features of microchannel heat exchanger 100 and/or microchannel heat exchanger 200.

[00038] According to various embodiments, the system 300 may further include the fan 720 coupled to the microchannel heat exchanger 200 to generate airflow 700 across the plurality of flat tubes 301 from the leading longitudinal edge portions 306 (i.e. windward side) to the trailing longitudinal edge portions 307 (i.e. leeward side) of the flat tubes 301. The fan 720 may be a propeller fan or a suction fan. The fan 720 in the form of the suction fan may be coupled to the microchannel heat exchanger 200 at a leeward side of the microchannel heat exchanger 200, such that the trailing longitudinal edge portions 307 of the plurality of flat tubes 301 are directed towards or opposing (e.g. facing) the fan 720. According to various embodiments, the fan 720 may be coupled to the microchannel heat exchanger 200 with a rotational axis 114 of the fan 720 being perpendicular to and intersecting (or in intersection with) the line of symmetry 111 of the microchannel heat exchanger 200. Accordingly, when the fan 720 is powered up or turned on, the fan 720 may generate an airflow 700 having a hyperbolical airflow pattern 710 across the microchannel heat exchanger 200, as shown in FIG. 3. Each flat tube 301 of the microchannel heat exchanger 200 may be inclined or slanted such that the flat tube 301 is parallel with a respectively local airflow (or air steam) of the hyperbolical airflow pattern 710 that comes into contact with the flat tube 301. Hence, according to various embodiments, the outer base surface 303 and the outer upper surface 304 of each flat tube 301 may be parallel with a respectively local airflow (or air steam) of the hyperbolical airflow pattern 710 that comes into contact with the flat tube 301.

[00039] As shown, the system 300 may further include an air outlet orifice 730 that may be arranged adjacent to the fan 720 for airflow out of the system 300.

[00040] Various embodiments have provided a microchannel heat exchanger with improved defrosting and heating capabilities. In various embodiments, each flat tube of the microchannel heat exchanger may be angled (or inclined or slanted) such that it is parallel with a local airflow of an actual airflow pattern, for example a hyperbolic airflow pattern, which may reduce air resistance across the microchannel heat exchanger and enable water (e.g. dew) that is collected on the upper surfaces of the flat tubes to fall off the microchannel heat exchanger easily. The microchannel heat exchanger may also include vertical fins of a reduced sized which may perform heat transfer with a surrounding atmosphere efficiently. According to various embodiments, the microchannel heat exchanger may be easy to use, such as being easily retrofitted to an existing any air sourced heat pump outdoor units.

[00041] While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes, modification, variation in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims. The scope of the invention is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.