CN115420120A - Parallel flow micro-channel heat exchanger - Google Patents

Abstract

A parallel flow micro-channel heat exchanger comprises a front row of heat exchange core bodies, a rear row of heat exchange core bodies, a fluid inlet pipe, a fluid outlet pipe, a first communicating block, a second communicating block, a fixing block and the like. The outer contours of the rear-row heat exchange core body and the front-row heat exchange core body are equal in size and are arranged in parallel front and back. The first communicating block and the second communicating block are located between the front heat exchange core body and the rear heat exchange core body and are block bodies which are provided with inner concave arc shapes at the front and the rear and are provided with communicating holes inside. When the heat exchanger works, external air sequentially flows through the front row of heat exchange cores and the rear row of heat exchange cores, and fluid exchanging heat with the air flows in through the fluid inlet pipe, sequentially flows through the upper parts of the front row of heat exchange cores, the first communicating block, the upper parts of the rear row of heat exchange cores, the lower parts of the rear row of heat exchange cores, the second communicating block and the lower parts of the front row of heat exchange cores, and finally flows out through the fluid outlet pipe. The parallel flow micro-channel heat exchanger is suitable for occasions with limited installation space, particularly small windward area and large heat exchange area.

Description

Parallel Flow Microchannel Heat Exchanger

technical field

The invention relates to a parallel flow microchannel heat exchanger, which can be used in the fields of refrigeration, air conditioning and environment control.

Background technique

Parallel flow heat exchanger is a new type of heat exchanger, which is generally used as a condenser for heat exchange between refrigerant and air in the field of refrigeration and air conditioning. Compared with finned tube heat exchangers, parallel heat exchangers are usually made of all-aluminum alloy materials, which have the advantages of light weight, high heat exchange efficiency, less refrigerant charge, and compact structure. The heat exchange core part of the parallel flow heat exchanger is usually composed of multiple porous flat tubes arranged in parallel, corrugated fins in the middle of the parallel flat tubes, and headers at both ends of the flat tubes. When the equivalent diameter of the pores in the porous flat tube belongs to the size range of the microchannel, this parallel flow heat exchanger can also be called a parallel flow microchannel heat exchanger.

When the parallel flow microchannel heat exchanger is used as a condenser, the refrigerant flows in the horizontal direction in the microchannel flat tube, and the flow direction of the air flowing through the fins from the outside of the heat exchanger is perpendicular to the flow direction of the refrigerant, that is, the refrigerant The flow direction in the flat tube is perpendicular to the windward direction. Due to the limitation of the manufacturing process, the header section of the existing parallel-flow microchannel heat exchanger is usually circular, and the heat exchange cores can generally only be made into a single row. When it is necessary to increase the heat transfer area of the parallel flow microchannel heat exchanger, it can only be achieved by increasing the fin spacing, increasing the windward area, and increasing the width of flat tubes and fins. Enlarging the fin spacing will increase the air flow resistance and fan power consumption; increasing the windward area will be limited by the installation space. Especially in some small or micro heat exchange equipment, the size of the air duct is very narrow, so parallel flow micro channel heat exchangers with large windward area cannot be used. If you want to increase the heat exchange area of parallel flow microchannel heat exchanger with the same windward area, the usual way is to increase the width of flat tubes and fins, but the increase in the width of flat tubes and fins will cause brazing The quality is difficult to guarantee, the leakage rate increases, and the product yield rate decreases. Moreover, since the width of the flat tube and fins increases, the diameter of the headers on both sides also increases accordingly, resulting in a decrease in the windward area of the core. In order to achieve the expansion of the total heat transfer area under the condition of constant windward area and avoid related defects, it is necessary to improve the structure of the existing parallel flow microchannel heat exchanger.

Contents of the invention

In view of the above problems, the present invention provides a multi-row parallel flow microchannel heat exchanger, which can realize the expansion of the total heat exchange area under the condition that the windward area of the heat exchanger remains unchanged.

The parallel flow microchannel heat exchanger of the present invention is used for fluid and air heat exchange, comprising:

Front row heat exchange core;

The rear row of heat exchange cores, the rear row of heat exchange cores and the front row of heat exchange cores are placed side by side, and the outer contour of the front row of heat exchange cores is equal in size;

A fluid inlet pipe, the fluid inlet pipe is installed on the front heat exchange core;

a fluid outlet pipe, the fluid outlet pipe is installed on the front heat exchange core;

The first communication block, the first communication block is located between the front row of heat exchange cores and the rear row of heat exchange cores, the first communication block has a concave arc shape in the front and back and has a communication connection inside. The block body of the hole, and the direction of the central axis of the communication hole is consistent with the windward direction of the front heat exchange core;

The second communication block, the second communication block is located between the front row of heat exchange cores and the rear row of heat exchange cores, the second communication block also has a concave arc surface shape in the front and back and has a A block of communication holes, and the direction of the central axis of the communication hole is consistent with the windward direction of the front heat exchange core;

fixed blocks, the several fixed blocks are located between the front row heat exchange cores and the rear row heat exchange cores, and the fixed blocks are blocks with concave arc-shaped front and rear and no holes inside, The number of said fixed block is at least one.

The front heat exchange cores, rear heat exchange cores, fluid inlet pipes, fluid outlet pipes, first connecting block, second connecting block, and fixing block are all made of aluminum alloy and integrally welded in a brazing furnace Shaped to form a complete parallel flow microchannel heat exchanger.

When the parallel flow microchannel heat exchanger is working: the external air flows through the front heat exchange cores and the rear heat exchange cores in sequence; after the fluid for heat exchange with the air flows in from the fluid inlet pipe, sequentially flows through the upper part of the front heat exchange core, the first connecting block, the upper part of the rear heat exchange core, the lower part of the rear heat exchange core, the second communication block, the front row After the lower part of the heat exchange core, the fluid flows out of the parallel flow microchannel heat exchanger through the outlet pipe.

The front heat exchange core includes a first header, a second header, a plurality of parallel microchannel flat tubes between the first header and the second header, and a plurality of parallel microchannel flat tubes. The corrugated fins in between, the first dividing plate inside the first header, and the second dividing plate inside the second header. The first header and the second header are hollow cylinders. An inlet hole and an outlet hole are arranged on the tube wall of the first header from top to bottom, and the inlet hole and the outlet hole face the front of the front heat exchange core body, and the inlet hole and the outlet hole are The outlet hole is separated by the first partition plate; a first communication hole and a second communication hole are arranged on the pipe wall of the second header from top to bottom, and the first communication hole and the second communication hole The second communication hole faces the back of the front heat exchange core (that is, faces the rear heat exchange core), and the first communication hole and the second communication hole are separated by the second board separated.

The rear heat exchange core includes a third header, a fourth header, a plurality of microchannel flat tubes arranged in parallel between the third header and the fourth header, and a plurality of parallel microchannel flat tubes located between the third header and the fourth header. The corrugated fins between, and the third partition located in the fourth header. The third header and the fourth header are hollow cylinders. A third communication hole and a fourth communication hole are provided from top to bottom on the tube wall of the fourth header, and the third communication hole and the fourth communication hole face the front of the rear row of heat exchange cores ( That is, facing the front heat exchange core), the third communication hole and the fourth communication hole are aligned with the first communication hole and the second communication hole on the second header respectively in the height direction, And the third communication hole and the fourth communication hole are separated by the third partition plate.

The fluid inlet pipe is welded in the inlet hole of the first header of the front row heat exchange core, and the fluid that exchanges heat with air flows into the parallel flow microchannel heat exchanger.

The fluid outlet pipe is welded in the outlet hole of the first header of the front row heat exchange core, and the fluid after heat exchange with air flows out of the parallel flow microchannel heat exchanger.

The communication hole in the middle of the first communication block is respectively aligned with the first communication hole on the second header and the third communication hole on the fourth header, and the front arc surface of the first communication block It is tangent to the cylindrical surface of the second header, and the back arc surface of the first communication block is tangent to the cylindrical surface of the fourth header. The purpose of doing this is to make the distance between the front row of heat exchange cores and the rear row of heat exchange cores as small as possible.

Similarly, the communication holes in the middle of the second communication block are respectively aligned with the second communication holes on the second header and the fourth communication holes on the fourth header, and the communication holes of the second communication block The front arc surface is tangent to the cylindrical surface of the second header, and the back arc surface of the second communication block is tangent to the cylindrical surface of the fourth header.

The communication hole between the first communication block and the second communication block may be any one of a circular hole, an oblong hole, a regular polygonal hole or a rectangular hole.

The fixing block is used to connect the front row of heat exchange cores and the rear row of heat exchange cores. The fixing block is placed between the first header and the third header, at this time, the front arc surface of the fixing block is tangent to the cylindrical surface of the first header, and the back of the fixing block The arc surface is tangent to the cylindrical surface of the third header.

Further, the fixing block can also be placed between the second header and the fourth header to increase the strength of the entire parallel flow microchannel heat exchanger. At this time, the front arc surface of the fixing block is tangent to the cylindrical surface of the second header, and the back arc surface of the fixing block is tangent to the cylindrical surface of the fourth header.

By adopting the above technical solution, the parallel flow microchannel heat exchanger of the present invention can double the heat exchange area of the heat exchanger without increasing the windward area. With this technical solution, the heat exchanger is easy to manufacture and leak detection, and it is not easy to have the problems of difficult welding of the fins, increased leakage rate, and decreased product yield when the heat exchange area is increased simply by increasing the width of the fins. It avoids the problem that the header diameter increases and the actual windward area decreases instead due to the increase in the width of the flat tube and the fins.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Figure 1 is a perspective view of the parallel flow microchannel heat exchanger.

Figure 2 is a perspective view of the parallel flow microchannel heat exchanger in another direction.

Fig. 3 is a front view of the front heat exchange core.

Fig. 4 is a front view of the rear heat exchange core.

Fig. 5 is a perspective view of the first connected block, and the structure of the second connected block is the same as that of the first connected block.

Fig. 6 is a perspective view of the fixing block.

Fig. 7 is a schematic structural diagram of an alternative embodiment of the first connected block or the second connected block.

Fig. 8 is a schematic structural diagram of another implementation option of the first communication block or the second communication block.

detailed description

Embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

Please refer to Fig. 1 and Fig. 2, according to an embodiment of the present invention, the present invention provides a parallel flow microchannel heat exchanger, which includes a front heat exchange core 1, a rear heat exchange core 2, a fluid inlet The pipe 3, the fluid outlet pipe 4, the first communication block 5, the second communication block 6, and the fixing block 7, wherein the number of the fixing block 7 is at least one. The front heat exchange core 1, the rear heat exchange core 2, the fluid inlet pipe 3, the fluid outlet pipe 4, the first connecting block 5, the second connecting block 6, and the fixing block 7 are all made of aluminum alloy, and It is integrally welded and formed in a brazing furnace to form a complete parallel flow microchannel heat exchanger.

As shown in FIG. 3 , the front row heat exchange core 1 includes a first header 11 , a second header 12 , and a plurality of microchannels arranged in parallel between the first header 11 and the second header 12 Flat tubes 13, corrugated fins 14 located between multiple parallel microchannel flat tubes 13 (only part of the fins are shown in the figure for clarity of the drawing), and first partitions located inside the first header 11 plate 15, and a second partition plate 16 located inside the second header 12. The first header 11 and the second header 12 are hollow cylinders. On the first header 11, an inlet hole 11a and an outlet hole 11b are arranged from top to bottom, and the inlet hole 11a and the outlet hole 11b face the front of the front heat exchange core 1, and the The inlet hole 11a and the outlet hole 11b are separated by the first partition plate 15; on the tube wall of the second header 12, a first communication hole 12a and a second communication hole 12a are arranged from top to bottom. hole 12b, the first communication hole 12a and the second communication hole 12b face the back of the front heat exchange core 1 (that is, face the rear heat exchange core 2), and the first communication hole 12a and the second communication hole 12 b are separated by the second partition plate 16 .

As shown in FIG. 1 and FIG. 2 , the rear heat exchange cores 2 and the front heat exchange cores 1 are placed side by side, and have the same outer contour size as the front heat exchange cores 1 .

As shown in FIG. 4 , the rear heat exchange core 2 includes a third header 21 , a fourth header 22 , and a plurality of microchannels arranged in parallel between the third header 21 and the fourth header 22 Flat tubes 23, corrugated fins 24 between a plurality of parallel microchannel flat tubes 23 (only part of the fins are shown in the figure to make the drawing clear), and the third compartment located in the fourth header 22 plate 26. The third header 21 and the fourth header 22 are hollow cylinders. On the pipe wall of the fourth header 22, a third communication hole 22a and a fourth communication hole 22b are arranged from top to bottom, and the third communication hole 22a and the fourth communication hole 22b are exchanged towards the rear. The front of the thermal core 2 (that is, facing the front row of heat exchange cores 1), the third communication hole 22a and the fourth communication hole 22b are respectively connected to the second header 12 in the height direction. The first communication hole 12 a and the second communication hole 12 b are aligned, and the third communication hole 22 a and the fourth communication hole 22 b are separated by the third partition plate 26 .

As shown in FIG. 1 , FIG. 2 and FIG. 3 , the fluid inlet pipe 3 is installed on the front heat exchange core 1 . In this embodiment, the fluid inlet pipe 3 is welded in the inlet hole 11a of the front row heat exchange core 1, and the fluid that exchanges heat with the air flows into the parallel flow microchannel heat exchanger.

As shown in FIG. 1 , FIG. 2 and FIG. 4 , the fluid outlet pipe 4 is installed on the front heat exchange core 1 . In this embodiment, the fluid outlet pipe 4 is welded in the outlet hole 11b of the front row heat exchange core 1, and the fluid after heat exchange with air flows out of the parallel flow microchannel heat exchanger.

As shown in Figure 1 and Figure 5, the first communication block 5 is located between the front heat exchange core 1 and the rear heat exchange core 2, and the first communication block 5 has a concave The front arc surface 5a and the concave back arc surface 5b, the first communication block 5 has a communication hole 5c inside, and the central axis direction of the communication hole 5c is consistent with the windward direction of the front heat exchange core 1 .

The communication hole in the middle of the first communication block 5 is respectively aligned with the first communication hole 12a on the second header 12 and the third communication hole 22a on the fourth header 22, and the first communication The front arc surface 5 a of the block 5 is tangent to the cylindrical surface of the second header 12 , and the back arc surface 5 b of the first communication block 5 is tangent to the cylindrical surface of the fourth header 22 . The purpose of doing this is to make the distance between the front row heat exchange core body 1 and the rear row heat exchange core body 2 as small as possible.

As shown in Figure 1 and Figure 5, the second communication block 6 is located between the front heat exchange core 1 and the rear heat exchange core 2, and the second communication block 6 also has front and rear A block with a concave arc surface shape and a communication hole inside, and the direction of the central axis of the communication hole is consistent with the windward direction of the front heat exchange core 1 . In this example, the first connected block 5 and the second connected block 6 take the same shape.

Similarly, the communication hole in the middle of the second communication block 6 is respectively aligned with the second communication hole 12b on the second header 12 and the fourth communication hole 22b on the fourth header 22, and the The front arc surface of the second communication block 6 is tangent to the cylindrical surface of the second header 12 , and the back arc surface of the second communication block 6 is tangent to the cylindrical surface of the fourth header 22 .

As shown in Fig. 2 and Fig. 6, the several fixing blocks 7 are located between the front row heat exchanging cores 1 and the rear row heat exchanging cores 2, and the fixing blocks 7 have concave front arcs surface 7a and the concave rear arc surface 7b, there is no hole inside the fixing block 7, and the number of the fixing block 7 is at least one.

The fixing block 7 is used to connect the front row heat exchange core body 1 and the rear row heat exchange core body 2 . The fixing block 7 is placed between the first header 11 and the third header 21, at this time, the front arc surface 7a of the fixing block 7 is tangent to the cylindrical surface of the first header 11, and the The back arc surface 7b of the fixing block 7 is tangent to the cylindrical surface of the third header 21 .

Further, but not necessarily, the fixed block 7 can also be placed between the second header 12 and the fourth header 22, to increase the strength of the entire parallel flow microchannel heat exchanger (not shown in the figure out). At this time, the front arc surface 7 a of the fixing block 7 is tangent to the cylindrical surface of the second header 12 , and the rear arc surface 7 b of the fixing block 7 is tangent to the cylindrical surface of the fourth header 22 .

The present invention has no limitation on the shape of the communication hole between the communication block 5 and the communication block 6 . The communication hole between the first communication block 5 and the second communication block 6 can be any one of circular hole, oblong hole, regular polygonal hole and rectangular hole. As shown in FIG. 7 , in an optional embodiment, a communication block whose middle communication hole is an oblong hole is used.

The present invention has no limitation on the shapes of the outer contours of the communication block 5 and the communication block 6 . The outer contour shape of the first communication block 5 and the second communication block 6 can be any one of rectangle, circle and regular polygon. As shown in FIG. 8 , in another optional embodiment, a communication block whose outer contour is circular is used.

In the embodiments shown in Figures 1 to 4, the external air flows through the front heat exchange cores 1 and the rear heat exchange cores 2 sequentially along the windward direction; The baffle effect, the fluid that exchanges heat with the air flows in from the fluid inlet pipe 3, and then flows through the upper part of the front heat exchange core 1, the first connecting block 5, the rear heat exchange core 2, the lower part of the rear heat exchange core 2, the second connecting block 6, and the lower part of the front heat exchange core 1, the fluid outlet pipe 4 flows out of the parallel flow microchannel exchange heater. The specific flow path of the fluid is: fluid inlet pipe 3→the inlet hole 11a on the upper part of the first header 11→the upper space of the first header 11→several parallel microchannel flat tubes 13 on the upper part of the front heat exchange core 1 → the upper space of the second header 12 → the first communication hole 12a on the upper part of the second header 12 → the first communication block 5 → the third communication hole 22a on the upper part of the fourth header 22 → the upper space of the fourth header 22 → several parallel microchannel flat tubes 23 on the upper part of the rear heat exchange core 2 → the upper space of the third header 21 → the lower space of the third header 21 → several parallel parallel tubes on the lower part of the rear heat exchange core 2 The microchannel flat tube 23 → the fourth communication hole 22b at the bottom of the fourth header 22 → the second communication block 6 → the second communication hole 12b at the bottom of the second header 12 → the lower space of the second header 12 → the front row Several parallel microchannel flat tubes 13 at the lower part of the heat exchange core 1 → the outlet hole 11 b at the lower part of the first header 11 → the fluid outlet pipe 4 .

Based on the technical solution described in the present invention, the position of the first partition plate 15, the second partition plate 16, and the third partition plate 26 in the corresponding headers can be adjusted flexibly when the fluid flows along the tube side. The number of microchannel flat tubes passed. In this embodiment, the number of microchannel flat tubes that the front row of heat exchange cores 1 and the rear row of heat exchange cores 2 have is 13 (the uppermost and lowermost plates in the figure are thin plates that play a fixed role sheet, non-flowable flat tube), and the number of microchannel flat tubes passed by the fluid along the tube side is 8-7-6-5 in sequence, that is, the flow cross-sectional area of the fluid decreases continuously along the tube side. This configuration Suitable for use in conditions where fluids condense. This is because under condensation conditions, the fluid is in a gaseous state when it first enters the parallel flow microchannel heat exchanger, and its specific volume is relatively large. However, in the process of flowing along the tube side, the fluid continuously condenses and becomes liquid, and its specific volume gradually decreases. Small, so the required cross-sectional area of the flow channel is continuously decreasing along the tube path.

The parallel-flow micro-channel heat exchanger provided by the present invention can double the total heat exchange area of the heat exchanger under the condition that the windward area and the width of the fins remain unchanged, and is suitable for small windward area of the flow channel and large size of the equipment. Where the installation size is limited, it is especially suitable for small and miniature HVAC equipment.

It should be pointed out that the above embodiments are described based on double rows of heat exchange cores, but the present invention does not limit the number of rows of heat exchange cores. Based on the technical solution described in the present invention, a parallel flow microchannel heat exchanger with three, four or even more rows of heat exchange cores can also be constructed with slight modifications, and the windward area can still be kept constant.

As used above, "communication" refers to a portion of the material that has cavities that are connected together to allow fluid to flow therethrough.

In this article, the orientation words such as length direction, width direction, height direction, front, back, up, down, left, right, inside, outside, middle, end, side are the parts in the drawings. It is defined in the center and the position between parts and components only for the clarity and convenience of expressing the technical solution. It should be understood that the use of the location words should not limit the scope of protection claimed in this application.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (6)

1. A parallel flow microchannel heat exchanger for exchanging heat between a fluid and air, comprising: the heat exchanger comprises a front row of heat exchange cores, a rear row of heat exchange cores, a fluid inlet pipe, a fluid outlet pipe, a first communicating block, a second communicating block and a fixing block; the rear-row heat exchange core body and the front-row heat exchange core body are arranged in parallel front and back and have the same size with the outer contour of the front-row heat exchange core body; the first communicating block and the second communicating block are positioned between the front row of heat exchange cores and the rear row of heat exchange cores, the first communicating block and the second communicating block are block bodies which are provided with concave arc shapes at the front and the rear and are internally provided with communicating holes, and the central axis direction of the communicating holes is consistent with the windward direction of the front row of heat exchange cores; the fixed blocks are positioned between the front-row heat exchange core body and the rear-row heat exchange core body, the fixed blocks are blocks which are provided with inner concave arc shapes at the front and the rear and are not provided with holes inside, and the number of the fixed blocks is at least 1; when the parallel flow micro-channel heat exchanger works, external air sequentially flows through the front row of heat exchange core bodies and the rear row of heat exchange core bodies along the windward direction, and fluid exchanging heat with the air flows through the upper portion of the front row of heat exchange core bodies, the first communicating block, the upper portion of the rear row of heat exchange core bodies, the lower portion of the rear row of heat exchange core bodies, the second communicating block and the lower portion of the front row of heat exchange core bodies sequentially after flowing in through the fluid inlet pipe, and then flows out of the parallel flow micro-channel heat exchanger through the fluid outlet pipe.

2. The parallel flow microchannel heat exchanger of claim 1, wherein: the front row heat exchange core body comprises a first collecting pipe, a second collecting pipe, a plurality of micro-channel flat pipes which are arranged in parallel and are positioned between the first collecting pipe and the second collecting pipe, corrugated fins which are positioned between the plurality of parallel micro-channel flat pipes, a first partition plate positioned in the first collecting pipe, and a second partition plate positioned in the second collecting pipe; the first collecting pipe and the second collecting pipe are hollow cylinders; an inlet hole and an outlet hole are formed in the tube wall of the first header from top to bottom, the inlet hole and the outlet hole face the front of the front row heat exchange core, and the inlet hole and the outlet hole are separated by the first partition plate; first communication holes and second communication holes are formed in the tube wall of the second header from top to bottom, face the rear face of the front row heat exchange core (i.e., face the rear row heat exchange core), and are partitioned by the second partition plate.

3. The parallel flow microchannel heat exchanger of claim 1, wherein: the rear-row heat exchange core body comprises a third collecting pipe, a fourth collecting pipe, a plurality of micro-channel flat pipes which are arranged in parallel and positioned between the third collecting pipe and the fourth collecting pipe, corrugated fins positioned between the plurality of parallel micro-channel flat pipes and a third clapboard positioned in the fourth collecting pipe; the third collecting pipe and the fourth collecting pipe are hollow cylinders; third and fourth communication holes are provided in a tube wall of the fourth header from top to bottom, the third and fourth communication holes facing the front of the rear row heat exchange core (i.e., facing the front row heat exchange core), the third and fourth communication holes are respectively aligned in the height direction with the first and second communication holes in the second header, and the third and fourth communication holes are partitioned by the third partition plate.

4. The parallel flow microchannel heat exchanger of claim 1, wherein: the communication hole in the middle of the first communication block is respectively aligned with the first communication hole in the second header and the third communication hole in the fourth header, the front cambered surface of the first communication block is tangent to the cylindrical surface of the second header, and the rear cambered surface of the first communication block is tangent to the cylindrical surface of the fourth header; the communication hole in the middle of the second communication block is respectively aligned with the second communication hole in the second header and the fourth communication hole in the fourth header, the front cambered surface of the second communication block is tangent to the cylindrical surface of the second header, and the rear cambered surface of the second communication block is tangent to the cylindrical surface of the fourth header.

5. The parallel flow microchannel heat exchanger of claim 1, wherein: the fixed block is placed between the first header and the third header, the front cambered surface of the fixed block is tangent to the cylindrical surface of the first header, and the rear cambered surface of the fixed block is tangent to the cylindrical surface of the third header.

6. The parallel flow microchannel heat exchanger of claim 1, wherein: the communication hole between the first communication block and the second communication block can be any one of a round hole, a long round hole, a regular polygonal hole or a rectangular hole.

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