CN117213269A - Microchannel heat exchanger, refrigerant circulation system and heat pump water heater - Google Patents

Abstract

The application relates to a micro-channel heat exchanger, a refrigerant circulating system and a heat pump water heater, wherein the micro-channel heat exchanger comprises: a refrigerant inlet (4) for introducing a refrigerant exchanging heat with an external medium; a refrigerant outlet (5) for outputting a refrigerant after heat exchange with the external medium; the flat pipes (3) are arranged side by side along a first direction, the flat pipes (3) extend along a second direction perpendicular to the first direction, one end of each flat pipe (3) along the second direction is communicated with the refrigerant inlet (4), and the other end of each flat pipe is communicated with the refrigerant outlet (5); the ratio of the total volume of the flat tubes (3) to the area of the heat exchange outer surface of the microchannel heat exchanger is 0.3 to 0.5.

Description

Microchannel heat exchanger, refrigerant circulation system and heat pump water heater

Technical Field

The application relates to a micro-channel heat exchanger, a refrigerant circulating system and a heat pump water heater.

Background

The refrigerant (refrigerant) is the 'blood' of the heat pump system, the heat pump system is a closed system, the system pipeline and the components are required to be filled by liquid and gaseous refrigerants to maintain the normal circulation state, namely the heat pump system pipeline and the components can 'store' the refrigerant. Under the condition of a certain refrigerant filling amount, the more the pipeline refrigerant is stored, the less the effective refrigerant participating in the heat pump cycle is, the lower the refrigerant utilization rate is, and the worse the system performance is. Generally, increasing the refrigerant filling amount of the heat pump system can improve the nominal working condition and the high-temperature heating amount, but at the same time, too much refrigerant at low temperature can cause poor reliability. In addition, for the heat pump system with limited refrigerant filling amount (such as an air energy water heater adopting R290 as a refrigerant (a vertical water tank), the refrigerant filling amount is less than or equal to 152 g), the refrigerant storage amount of a system pipeline is reduced, and the improvement of the utilization rate of the system refrigerant becomes important.

Disclosure of Invention

The application aims to provide a micro-channel heat exchanger, a refrigerant circulating system and a heat pump water heater, which are beneficial to improving the utilization rate of a refrigerant.

According to an aspect of an embodiment of the present application, there is provided a microchannel heat exchanger, the microchannel heat exchanger comprising:

a first header extending in a first direction;

the second collecting pipe is arranged side by side with the first collecting pipe at intervals;

the flat pipes are arranged between the first collecting pipe and the second collecting pipe side by side along the first direction, extend along the second direction perpendicular to the first direction, and are communicated with the first collecting pipe at one end along the second direction and the second collecting pipe at the other end;

the ratio of the total volume of the plurality of flat tubes to the area of the heat exchange outer surface of the microchannel heat exchanger is 0.3 to 0.5.

In some embodiments, a microchannel heat exchanger comprises:

the first heat exchange area comprises at least one flat tube;

the second heat exchange area comprises at least one flat tube, and is positioned at the downstream of the first heat exchange area along the flowing direction of the refrigerant;

the ratio of the total volume of the flat tubes of the first heat exchange zone to the area of the heat exchange outer surface of the first heat exchange zone is greater than the ratio of the total volume of the flat tubes of the second heat exchange zone to the area of the heat exchange outer surface of the second heat exchange zone.

In some embodiments of the present application, in some embodiments,

the ratio of the total volume of the flat tubes of the first heat exchange area to the area of the heat exchange outer surface of the first heat exchange area is 0.4 to 0.5; and/or

The ratio of the total volume of the flat tubes of the second heat exchange zone to the area of the heat exchange outer surface of the second heat exchange zone is 0.28-0.37.

In some embodiments, the cross section of the flat tube perpendicular to the second direction is a bar, the flat tube comprises a plurality of channels for flowing refrigerant, which are arranged side by side along the length direction of the bar and extend along the second direction,

the number of the pore passages of the flat tubes of the first heat exchange area is larger than that of the pore passages of the flat tubes of the second heat exchange area; and/or

The area of the cross section of the portholes of the flat tubes of the first heat transfer area is larger than the area of the cross section of at least part of the portholes of the flat tubes of the second heat transfer area.

In some embodiments of the present application, in some embodiments,

the flat tubes of the first heat exchange area are configured to circulate a superheated refrigerant with a temperature higher than a saturation temperature;

the flat tubes of the second heat exchange zone are configured to circulate a refrigerant that coexists in a gaseous state and a liquid state.

In some embodiments, the inner walls of the portholes in the flat tubes of the second heat transfer area are provided with protruding structures.

In some embodiments, the raised structures extend in the second direction or extend helically on the inner wall of the cell channel.

In some embodiments, the microchannel heat exchanger further comprises a third heat exchange zone downstream of the second heat exchange zone in the direction of refrigerant flow, the third heat exchange zone comprising at least one flat tube, the ratio of the total volume of the flat tubes of the third heat exchange zone to the area of the heat exchange outer surface of the third heat exchange zone being less than the ratio of the total volume of the flat tubes of the first heat exchange zone to the area of the heat exchange outer surface of the first heat exchange zone.

In some embodiments, the ratio of the total volume of the flat tubes of the third heat transfer zone to the area of the heat transfer outer surface of the third heat transfer zone is equal to or less than the ratio of the total volume of the flat tubes of the second heat transfer zone to the area of the heat transfer outer surface of the second heat transfer zone.

In some embodiments, the ratio of the total volume of the flat tubes of the third heat transfer zone to the area of the heat transfer outer surface of the third heat transfer zone is 0.28-0.37.

In some embodiments, the ratio of the total volume of the flat tubes of the third heat transfer zone to the area of the heat transfer outer surface of the third heat transfer zone is 0.25-0.33.

In some embodiments, the flat tubes of the second heat exchange zone are configured to circulate a refrigerant having a temperature below the saturation temperature.

In some embodiments, further comprising:

a first isolating component which is arranged in the first collecting pipe to block the inner cavity of the first collecting pipe,

the microchannel heat exchanger comprises a first group of flat tubes positioned on one side of the first isolation component and a second group of flat tubes positioned on the other side of the first isolation component, wherein the first ends of the first group of flat tubes along the second direction are separated from the first ends of the second group of flat tubes along the second direction by the first isolation component, and the second ends of the first group of flat tubes along the second direction are communicated with the second ends of the second group of flat tubes through a second collecting pipe.

According to another aspect of the application, a refrigerant circulation system is further provided, and the microchannel heat exchanger of the refrigerant circulation system is provided.

According to another aspect of the present application, there is also provided a heat pump water heater including the above refrigerant circulation system.

By applying the technical scheme of the application, the ratio of the total volume of the flat tubes to the area of the heat exchange outer surface of the microchannel heat exchanger is optimized, so that the refrigerant in the flat tubes can exchange heat with the heat exchange medium sufficiently, and the heat exchange performance of the refrigerant circulation system can be ensured on the premise of effectively reducing the refrigerant filling quantity. Even under the condition that the first heat exchanger is at low temperature, the external heat can be fully utilized, so that the low-temperature performance of the system is improved.

Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments of the application, which proceeds with reference to the accompanying drawings.

Drawings

In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the application, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.

FIG. 1 shows a schematic structural view of a heat pump water heater according to an embodiment of the present application;

FIG. 2 shows a schematic structural diagram of a microchannel heat exchanger of an embodiment of the application;

FIG. 3 shows a schematic view of the heat exchange tubes of the first heat exchange zone of the microchannel heat exchanger according to an embodiment of the application; and

FIG. 4 shows a schematic view of the heat exchange tubes of the second heat exchange zone of the microchannel heat exchanger in accordance with an embodiment of the application;

FIG. 5 shows a schematic view of the heat exchange tubes of the third heat exchange zone of the microchannel heat exchanger in accordance with an embodiment of the application;

FIG. 6 shows a schematic view of a heat exchange tube of a second heat exchange zone of a microchannel heat exchanger in accordance with another alternative embodiment of the application;

FIG. 7 shows a schematic view of a heat exchange tube of a second heat exchange zone of a microchannel heat exchanger in accordance with another alternative embodiment of the application; and

fig. 8 shows a schematic structural view of a heat exchange tube of a second heat exchange zone of a microchannel heat exchanger according to another alternative embodiment of the application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

As shown in fig. 1, the heat pump water heater of the present embodiment includes a refrigerant circulation system including a compressor 10, a first heat exchanger 40 and a second heat exchanger 60, one of the first heat exchanger 40 and the second heat exchanger 60 serving as a condenser and the other serving as an evaporator, the condenser being in communication with an exhaust port of the compressor 10 to condense compressed refrigerant discharged from the compressor 10, the evaporator being in communication with an intake port of the compressor 10 to convey the evaporated refrigerant to the compressor 10 for recompression. The heat pump water heater further comprises a heat exchange medium tank 70 exchanging heat with the second heat exchanger 60. The side of the second heat exchanger 60 is attached to the heat exchange medium case 70. The side surface of the second heat exchanger 60 attached to the heat exchange medium case 70 exchanges heat with the heat exchange medium in the heat exchange medium case 70.

In some embodiments, the heat exchange medium comprises water. The heat exchange medium tank 70 includes a water tank.

In some embodiments, the refrigerant circulation system further includes a four-way valve 30, the four-way valve 30 including an inlet D in communication with the discharge port of the compressor 10, an outlet S in communication with the suction port of the compressor 10, a first working port E in communication with the first heat exchanger 40, and a second working port C in communication with the second heat exchanger 60. The four-way valve 30 has a first operating state and a second operating state. When the four-way valve 30 is in the first working state, the inlet D is communicated with the first working port E, the outlet S is communicated with the second working port C, the first heat exchanger 40 is a condenser, and the second heat exchanger is an evaporator. When the four-way valve 30 is in the second operating state, the inlet D is in communication with the second operating port C, the outlet S is in communication with the first operating port E, the first heat exchanger 40 acts as an evaporator, and the second heat exchanger 60 acts as a condenser.

In some embodiments, the compressor further comprises a gas-liquid separator 20 in communication with the suction port of the compressor 10, wherein an inlet of the gas-liquid separator 20 is in communication with the outlet S of the four-way valve 30, and an outlet of the gas-liquid separator 20 is in communication with the suction port of the compressor 10.

In some embodiments, the refrigerant circulation system further includes a fan 50 for driving the heat exchange of air with the first heat exchanger 40. The refrigerant circulation system further includes a throttling part 80 located between the first heat exchanger 40 and the second heat exchanger 60 in the refrigerant flow direction.

In the present embodiment, the second heat exchanger 60 is a microchannel heat exchanger, also referred to as a microchannel heat exchanger.

As shown in fig. 2, the microchannel heat exchanger comprises a refrigerant inlet 4, a refrigerant outlet 5 and a plurality of flat tubes 3. The refrigerant inlet 4 is used for introducing a refrigerant exchanging heat with an external medium; the refrigerant outlet 5 is used for outputting a refrigerant subjected to heat exchange with an external medium; the flat tubes 3 are arranged side by side along a first direction, the flat tubes 3 extend along a second direction perpendicular to the first direction, one end of each flat tube 3 along the second direction is communicated with the refrigerant inlet 4, and the other end of each flat tube 3 is communicated with the refrigerant outlet 5; the ratio of the total volume of the plurality of flat tubes 3 to the area of the heat exchange outer surface of the microchannel heat exchanger is 0.3 to 0.5.

In this embodiment, the ratio of the total volume of the flat tubes 3 to the area of the heat exchange outer surface of the microchannel heat exchanger is optimized, so that the refrigerant in the flat tubes 3 can exchange heat with the heat exchange medium sufficiently, and the heat exchange performance of the refrigerant circulation system can be ensured on the premise of reducing the refrigerant filling amount effectively. Even under the condition that the first heat exchanger is at low temperature, the external heat can be fully utilized, so that the low-temperature performance of the system is improved.

The following table shows the comparison of the performance parameters of the microchannel condensers of different flat tube specifications:

for the pipelines or parts with the same volume, the density of the liquid refrigerant is far higher than that of the gaseous or gas-liquid mixed state refrigerant under the same temperature and pressure of the refrigerant, and the quantity of the liquid refrigerant stored in the pipeline or part is higher than that of the gas-liquid mixed state or gaseous refrigerantMany. For example, R290 refrigerant is adopted, and the densities of saturated liquid and saturated gas are 427.97kg/m respectively under the conditions of 60 ℃ temperature and 2.1168MPa pressure ³ And 49.49kg/m ³ ，1m ³ The mass of the liquid R290 refrigerant is 8.6 times that of the same volume of gas refrigerant. The refrigerant in the condenser is condensed into liquid state from gas, and the liquid in the condenser is more and occupies the refrigerant with high mass ratio. Therefore, the key of improving the refrigerant utilization rate of the refrigerant system is to reduce the refrigerant storage amount in the water tank heat exchanger, that is, reduce the inner volume of the second heat exchanger 60, on the premise of ensuring the area of the heat exchange outer surface of the microchannel heat exchanger.

The microchannel heat exchanger comprises a first heat exchange zone 3a and a second heat exchange zone 3b. The first heat exchange zone 3a comprises at least one flat tube 3; the second heat exchange area 3b comprises at least one flat tube 3, and the second heat exchange area 3b is positioned downstream of the first heat exchange area 3a along the flow direction of the refrigerant.

The ratio of the total volume of the flat tubes 3 of the first heat transfer zone 3a to the area of the heat transfer outer surface of the first heat transfer zone 3a is greater than the ratio of the total volume of the flat tubes 3 of the second heat transfer zone 3b to the area of the heat transfer outer surface of the second heat transfer zone 3b.

The refrigerant continuously exchanges heat with external media in the flowing process in the heat exchanger, the high-temperature refrigerant is gradually condensed into liquid refrigerant, the volume of the flat tube of the second heat exchange zone 3b positioned at the downstream is reduced, the refrigerant filling quantity is reduced, the flow rate of the refrigerant is improved, the turbulent heat exchange in the tube is enhanced, and the heat transfer performance of the microchannel heat exchanger is further improved.

In this embodiment, the flat tube 3 of the first heat exchange area 3a is directly connected to the refrigerant inlet 4, when the second heat exchanger 60 is used as a condenser, the first heat exchange area 3a is used for condensing the high-temperature and high-pressure refrigerant compressed by the compressor, the first heat exchange area 3a is a refrigerant superheat area, the refrigerant exists in the first heat exchange area 3a in a gaseous state, the volume occupied by the gaseous refrigerant under the same condensing pressure is larger than that occupied by the liquid refrigerant, if the inner volume of the microchannel flat tube heat exchanger is too small, the resistance loss of the heat exchanger is increased, and the heat exchange performance is reduced due to too large pressure drop. The second heat exchange area 3b is internally provided with a refrigerant condensed by the first heat exchange area 3a, the refrigerant in the second heat exchange area 3b is in a gas-liquid two-phase mixed state, the occupied volume of the liquid refrigerant is smaller than that of the gaseous refrigerant under the same condensing pressure, the inner volume of the flat tube of the micro-channel heat exchanger is properly reduced, the flow velocity of the gas-liquid two-phase refrigerant is improved, turbulent heat exchange in the tube is enhanced, and the heat transfer performance of the micro-channel heat exchanger is improved.

In some embodiments, the ratio of the total volume of the flat tubes 3 of the first heat exchange zone 3a to the area of the heat exchange outer surface of the first heat exchange zone 3a is 0.4 to 0.5.

In some embodiments, the ratio of the total volume of the flat tubes 3 of the second heat exchange zone 3b to the area of the heat exchange outer surface of the second heat exchange zone 3b is 0.28-0.37.

The cross section of the flat tube 3 perpendicular to the second direction is a bar shape, and the flat tube 3 includes the duct 31 for flowing the refrigerant, which is arranged side by side along the length direction of the bar shape and extends along the second direction. In some embodiments, the cross section of the flat tube 3 is a bar extending in the first direction.

The number of the pore passages 31 of the flat tubes 3 of the first heat exchange area 3a is larger than the number of the pore passages 31 of the flat tubes 3 of the second heat exchange area 3 b; fig. 3 shows a schematic structural diagram of a cross section of the flat tube 3 of the first heat transfer zone 3a, and fig. 4 shows a schematic structural diagram of a cross section of the flat tube 3 of the second heat transfer zone 3b, wherein the number of the holes of the flat tube 3 of the first heat transfer zone 3a is larger than the number of the holes 31 of the flat tube 3 of the second heat transfer zone 3b, so that the volume of the flat tube 3 of the first heat transfer zone 3a is larger than the volume of the flat tube 3 of the second heat transfer zone 3b.

The area of the cross section of the portholes 31 of the flat tubes 3 of the first heat transfer zone 3a is larger than the area of the cross section of at least part of the portholes 31 of the flat tubes 3 of the second heat transfer zone 3b, fig. 3 shows a schematic structural diagram of the cross section of the flat tubes 3 of the first heat transfer zone 3a, fig. 4 shows a schematic structural diagram of the cross section of the flat tubes 3 of the second heat transfer zone 3b, the area of the cross section of the portholes of the flat tubes 3 of the first heat transfer zone 3a is larger than the area of the cross section of the portholes 31 of the flat tubes 3 of the second heat transfer zone 3b, so that the volume of the flat tubes 3 of the first heat transfer zone 3a is larger than the volume of the flat tubes 3 of the second heat transfer zone 3b.

In some embodiments, the inner walls of the channels 31 of the second heat exchange zone 3b are provided with protruding structures 32, so that the volume of the flat tubes 3 of the first heat exchange zone 3a is larger than the volume of the flat tubes 3 of the second heat exchange zone 3b. Further, the convex structure is arranged on the inner wall 3 of the pore canal 31, which is beneficial to strengthening turbulent heat exchange in the tube so as to improve the heat transfer performance of the micro-channel heat exchanger, and is beneficial to increasing the inner surface area of the pore canal 31 so as to improve the heat transfer performance.

In some embodiments, the protruding structure 32 extends along the second direction, and the protruding structure 32 is consistent with the length direction of the flat tube 3, which is beneficial to simplifying the manufacturing process and reducing the production cost. In other embodiments, the inner wall of the channel 31 extends spirally, which is beneficial to enhancing turbulence of the refrigerant in the channel 31 and improving heat exchange performance.

The microchannel heat exchanger further comprises a third heat exchange zone 3c located downstream of the second heat exchange zone 3b in the refrigerant flow direction, the third heat exchange zone 3c comprising at least one flat tube 3, the ratio of the total volume of the flat tubes 3 of the third heat exchange zone 3c to the area of the heat exchange outer surface of the third heat exchange zone 3c being smaller than the ratio of the total volume of the flat tubes 3 of the first heat exchange zone 3a to the area of the heat exchange outer surface of the first heat exchange zone 3 a.

The third heat exchange area 3c is used for condensing the refrigerant subjected to heat exchange by the second heat exchange area 3b, the refrigerant in the third heat exchange area 3c is in a supercooling state, and in the supercooling area, the proper reduction of the inner volume of the flat tube 3 of the microchannel heat exchanger is beneficial to improving the flow velocity of the liquid refrigerant, so that the heat transfer performance of the microchannel heat exchanger is improved.

In some embodiments, the ratio of the total volume of the flat tubes 3 of the third heat exchange zone 3c to the area of the heat exchange outer surface of the third heat exchange zone 3c is 0.28-0.37.

In some embodiments, the ratio of the total volume of the flat tubes 3 of the third heat transfer zone 3c to the area of the heat transfer outer surface of the third heat transfer zone 3c is equal to or smaller than the ratio of the total volume of the flat tubes 3 of the second heat transfer zone 3b to the area of the heat transfer outer surface of the second heat transfer zone 3b.

The refrigerant in the flat tube 3 of the third heat exchanger zone 3c is a liquid supercooled refrigerant with a temperature lower than the saturation temperature. The occupied volume of the liquid refrigerant is smaller than that of the gaseous refrigerant or the gas-liquid refrigerant under the same condensation pressure, and the proper reduction of the inner volume of the flat tube 3 of the third heat exchanger area 3c is beneficial to improving the flow velocity of the refrigerant, enhancing the turbulent heat exchange in the tube and further improving the heat transfer performance of the microchannel heat exchanger.

In some embodiments, the ratio of the total volume of the flat tubes 3 of the third heat exchange zone 3c to the area of the heat exchange outer surface of said third heat exchange zone 3c is 0.25-0.33.

In some embodiments, the cross section of the flat tube 3 perpendicular to the second direction is bar-shaped, and the flat tube 3 includes the channels 31 for flowing the refrigerant arranged side by side in the first direction and extending in the second direction.

The number of the pore passages 31 of the flat tubes 3 of the first heat exchange area 3a is larger than the number of the pore passages 31 of the flat tubes 3 of the third heat exchange area 3 c; fig. 3 shows a schematic structural diagram of a cross section of the flat tube 3 of the first heat transfer zone 3a, and fig. 5 shows a schematic structural diagram of a cross section of the flat tube 3 of the third heat transfer zone 3c, wherein the number of the holes of the flat tube 3 of the first heat transfer zone 3a is larger than the number of the holes 31 of the flat tube 3 of the third heat transfer zone 3c, so that the volume of the flat tube 3 of the first heat transfer zone 3a is larger than the volume of the flat tube 3 of the third heat transfer zone 3 c.

The area of the cross-section of the portholes 31 of the flat tubes 3 of the first heat exchanger zone 3a is larger than the area of the cross-section of at least part of the portholes 31 of the flat tubes 3 of the third heat exchanger zone 3 c. Fig. 3 shows a schematic structural diagram of a cross section of the flat tube 3 of the first heat transfer zone 3a, and fig. 5 shows a schematic structural diagram of a cross section of the flat tube 3 of the third heat transfer zone 3c, wherein the area of the cross section of the duct of the flat tube 3 of the first heat transfer zone 3a is larger than the area of the cross section of the duct 31 of the flat tube 3 of the third heat transfer zone 3c, so that the volume of the flat tube 3 of the first heat transfer zone 3a is larger than the volume of the flat tube 3 of the third heat transfer zone 3 c.

As shown in fig. 6 and 8, in some embodiments, the flat tubes 3 of the second heat transfer zone 3b or the third heat transfer zone 3c have a smaller number of portholes 31 relative to the flat tubes 3 of the first heat transfer zone 3 a.

As shown in fig. 7, in some embodiments, the flat tubes 3 of the second heat exchange zone 3b or the third heat exchange zone 3c comprise a first porthole 311 and a second porthole 312, the area of the cross section of the second porthole 312 being smaller than the area of the cross section of the first porthole 311.

The microchannel heat exchanger further comprises a first header 1, a second header 2 and a first spacer member 6. The first collecting pipe 1 is arranged at a first end of the flat pipe 3 along the second direction and is respectively communicated with the first ends of the plurality of flat pipes 3 along the second direction; the second collecting pipe 2 is arranged at the second end of the flat pipe 3 along the second direction and is respectively connected with the second ends of the flat pipes 3 along the second direction; the first separator 6 is provided in the first header 1 to block the inner cavity of the first header 1.

The microchannel heat exchanger comprises a first group of flat tubes 3 positioned on one side of a first isolation part 6 and a second group of flat tubes 3 positioned on the other side of the first isolation part 6, wherein the first ends of the first group of flat tubes 3 along the second direction are separated from the first ends of the second group of flat tubes 3 along the second direction by the first isolation part 6, and the second ends of the first group of flat tubes 3 along the second direction are communicated with the second ends of the second group of flat tubes 3 through a second collecting pipe 2. The flow path of the refrigerant in the heat exchanger is prolonged, so that the refrigerant is fully contacted with an external heat exchange medium for heat exchange.

Further, a second isolating component 7 is arranged in the second collecting pipe 2, the working principle of the second isolating component 7 is similar to that of the first isolating component 6, and the second isolating component is matched with the first isolating component 6 to enable the flat pipes 3 in the micro-channel heat exchanger to form a foldback channel, for example, the refrigerant in the flat pipes 3 of the first heat exchange area 3a flows from the first collecting pipe 1 to the second collecting pipe 2, the refrigerant in the flat pipes 3 of the second heat exchange area 3b flows from the second collecting pipe 2 to the first collecting pipe 1, and the refrigerant in the flat pipes 3 of the third heat exchange area 3c flows from the first collecting pipe 1 to the second collecting pipe 2.

Specifically, the flat tubes 3 of the first heat exchange zone 3a have an optimal ratio of flat tube internal volume to external surface area of 0.46. Taking a flat tube with a specification of 25.4mm (width) x 1.3mm (height) (the inner hole is square) as an example, the preferred number of holes is 26 holes, see fig. 3.

The flat tubes 3 of the second heat exchange zone 3b or the third heat exchange zone 3c have an optimal ratio of flat tube volume to outer surface area of 0.33. Taking a flat tube with the specification of 25.4mm (width) multiplied by 1.3mm (height) as an example, the preferable scheme is that the inner hole is designed into an internal tooth shape, and the number of holes is 21, see fig. 4 and 5.

According to another aspect of the present application, there is also provided a refrigerant circulation system, including the microchannel heat exchanger described above.

According to another aspect of the present application, there is also provided a heat pump water heater including the above refrigerant circulation system.

The foregoing is illustrative of the present application and is not to be construed as limiting thereof, but rather, any modification, equivalent replacement, improvement or the like which comes within the spirit and principles of the present application are intended to be included within the scope of the present application.

Claims (15)

1. A microchannel heat exchanger comprising:

a first header (1) extending in a first direction;

a second collecting pipe (2) which is arranged side by side with the first collecting pipe (1) at intervals;

the flat pipes (3) are arranged between the first collecting pipe (1) and the second collecting pipe (2) side by side along a first direction, the flat pipes (3) extend along a second direction perpendicular to the first direction, one end of each flat pipe (3) along the second direction is communicated with the first collecting pipe (1), and the other end of each flat pipe is communicated with the second collecting pipe (2);

the ratio of the total volume of the flat tubes (3) to the area of the heat exchange outer surface of the microchannel heat exchanger is 0.3 to 0.5.

2. The microchannel heat exchanger of claim 1, comprising:

a first heat exchange zone (3 a) comprising at least one of said flat tubes (3);

a second heat exchange area (3 b) comprising at least one flat tube (3), wherein the second heat exchange area (3 b) is positioned downstream of the first heat exchange area (3 a) along the flow direction of the refrigerant;

the ratio of the total volume of the flat tubes (3) of the first heat exchange zone (3 a) to the area of the heat exchange outer surface of the first heat exchange zone (3 a) is greater than the ratio of the total volume of the flat tubes (3) of the second heat exchange zone (3 b) to the area of the heat exchange outer surface of the second heat exchange zone (3 b).

3. The microchannel heat exchanger of claim 2 wherein,

the ratio of the total volume of the flat tubes (3) of the first heat exchange zone (3 a) to the area of the heat exchange outer surface of the first heat exchange zone (3 a) is 0.4 to 0.5; and/or

The ratio of the total volume of the flat tubes (3) of the second heat exchange zone (3 b) to the area of the heat exchange outer surface of the second heat exchange zone (3 b) is 0.28-0.37.

4. The microchannel heat exchanger according to claim 2, wherein the cross section of the flat tube (3) perpendicular to the second direction is strip-shaped, the flat tube (3) comprising a plurality of portholes (31) for flowing a refrigerant arranged side by side along the length of the strip and extending along the second direction,

the number of the pore passages (31) of the flat tubes (3) of the first heat exchange region (3 a) is larger than the number of the pore passages (31) of the flat tubes (3) of the second heat exchange region (3 b); and/or

The area of the cross section of the portholes (31) of the flat tubes (3) of the first heat exchange zone (3 a) is larger than the area of the cross section of at least part of the portholes (31) of the flat tubes (3) of the second heat exchange zone (3 b).

5. The microchannel heat exchanger of claim 2 wherein,

the flat tubes (3) of the first heat exchange area (3 a) are configured to circulate a superheated refrigerant with a temperature higher than a saturation temperature;

the flat tubes (3) of the second heat exchange zone (3 b) are configured to circulate a refrigerant in which a gaseous state and a liquid state coexist.

6. A microchannel heat exchanger according to any of claims 2-4, characterized in that the inner walls of the portholes (31) in the flat tubes (3) of the second heat exchange zone (3 b) are provided with protruding structures (32).

7. The microchannel heat exchanger according to any one of claims 6, wherein the raised structures (32) extend in the second direction or extend helically on the inner walls of the portholes (31).

8. The microchannel heat exchanger according to claim 2, further comprising a third heat exchange zone (3 c) downstream of the second heat exchange zone (3 b) in the direction of refrigerant flow, the third heat exchange zone (3 c) comprising at least one of the flat tubes (3), the ratio of the total volume of the flat tubes (3) of the third heat exchange zone (3 c) to the area of the heat exchange outer surface of the third heat exchange zone (3 c) being smaller than the ratio of the total volume of the flat tubes (3) of the first heat exchange zone (3 a) to the area of the heat exchange outer surface of the first heat exchange zone (3 a).

9. The microchannel heat exchanger according to claim 8, wherein the ratio of the total volume of the flat tubes (3) of the third heat exchange zone (3 c) to the area of the heat exchange outer surface of the third heat exchange zone (3 c) is equal to or smaller than the ratio of the total volume of the flat tubes (3) of the second heat exchange zone (3 b) to the area of the heat exchange outer surface of the second heat exchange zone (3 b).

10. The microchannel heat exchanger according to claim 9, characterized in that the ratio of the total volume of the flat tubes (3) of the third heat exchange zone (3 c) to the area of the heat exchange outer surface of the third heat exchange zone (3 c) is 0.28-0.37.

11. The microchannel heat exchanger according to claim 9 or 10, characterized in that the ratio of the total volume of the flat tubes (3) of the third heat exchange zone (3 c) to the area of the heat exchange outer surface of the third heat exchange zone (3 c) is 0.25-0.33.

12. The microchannel heat exchanger according to claim 8, wherein the flat tubes (3) of the second heat exchange zone (3 b) are configured to circulate a refrigerant having a temperature below saturation temperature.

13. The microchannel heat exchanger of claim 1, further comprising:

a first isolation component (6) which is arranged in the first collecting pipe (1) to block the inner cavity of the first collecting pipe (1),

the microchannel heat exchanger comprises a first group of flat tubes (3) positioned on one side of a first isolation component (6) and a second group of flat tubes (3) positioned on the other side of the first isolation component (6), wherein the first ends of the first group of flat tubes (3) along the second direction are separated from the first ends of the second group of flat tubes (3) along the second direction by the first isolation component (6), and the second ends of the first group of flat tubes (3) along the second direction are communicated with the second ends of the second group of flat tubes (3) through the second collecting pipe (2).

14. A refrigerant circulation system comprising a microchannel heat exchanger according to any one of claims 1 to 13.

15. A heat pump water heater comprising the refrigerant circulation system of claim 14.