Micro-channel heat exchanger, air conditioner using same and heat exchange method of air conditioner

Abstract

The application discloses a micro-channel heat exchanger, an air conditioner applying the same and a heat exchange method of the air conditioner, and relates to the field of air conditioner heat exchange equipment. The micro-channel heat exchanger comprises a first collecting pipe, a second collecting pipe and a plurality of heat exchange flat pipes which are arranged at intervals. One end of the heat exchange flat pipe is communicated with the first collecting pipe, and the other end is communicated with the second collecting pipe. The plurality of heat exchange flat pipes are located on the same horizontal plane. A plurality of flow channels with gradually decreasing cross sections are sequentially arranged in the heat exchange flat pipe from top to bottom. In the application, the cross section of the upper flow channel is increased, so that the phenomenon of uneven distribution of refrigerant mass flow between the upper and lower channels caused by the fact that the pressure at the inlet of the upper flow channel is less than that at the inlet of the lower flow channel is balanced, and the superheated vapor section in the upper flow channel is shortened, thereby improving the heat exchange effect of the overall micro-channel heat exchanger.

Description

Technical Field

[0001] This invention relates to the field of air conditioning heat exchange equipment, and in particular to a microchannel heat exchanger, an air conditioner using the same, and a heat exchange method for the air conditioner. Background Technology

[0002] Microchannel heat exchangers are widely used in air conditioning systems. They typically consist of several flat tubes arranged side by side, fins connected between the flat tubes to increase the heat transfer area, and gas and liquid manifolds connected to both ends of the flat tubes. Each flat tube contains several microchannels arranged side by side. Compared with traditional tubular heat exchangers, microchannel heat exchangers have the advantages of compact structure and high heat exchange efficiency.

[0003] Based on the flow direction of the working fluid within the microchannel flat tubes, microchannel heat exchangers can be categorized into horizontal flow and vertical flow types. Horizontal flow microchannel heat exchangers further exist in two configurations: horizontal and vertical arrangement of the manifolds. When a microchannel heat exchanger is used as an evaporator, its working principle is as follows: The refrigerant is injected into each flat tube from the liquid manifold at one end. Within the flat tubes, it continuously absorbs heat, causing the liquid refrigerant to gradually vaporize and completely transform into saturated vapor at the end of the flat tubes. Further heat absorption causes the refrigerant to form superheated vapor, which then collects in the gaseous manifold at the end of the flat tubes and enters the compressor.

[0004] For example, invention patents with application number "201510974414.9" entitled "Microchannel Heat Exchanger and its Flat Tube" and application number "201711064567.5" entitled "Heat Exchange Flat Tube and Microchannel Heat Exchanger" both disclose the structure of the heat exchange flat tube. However, when the flat tube is applied in a horizontal flow microchannel heat exchanger with horizontally arranged manifolds, the microchannels in any flat tube are arranged vertically. Due to the liquid refrigerant absorbing heat and transforming into superheated vapor, the pressure at different heights at the flat tube outlet is almost equal. But when the liquid refrigerant enters the flat tube, the pressure changes due to the liquid refrigerant absorbing heat and transforming into superheated vapor. Due to the presence of liquid gravity, the pressure at the inlet of the flat tube increases continuously from top to bottom. Consequently, the pressure difference between the inlet and outlet of each microchannel within the flat tube also increases continuously from top to bottom. This results in the refrigerant mass flow rate and velocity in the microchannel at the top of the flat tube being smaller than those in the microchannel at the bottom. This uneven distribution of mass flow rate causes the liquid refrigerant in the microchannel at the top of the flat tube to vaporize prematurely, forming an excessively long superheated vapor section. Since the heat exchange capacity of gas is much smaller than that of liquid or gas-liquid two-phase flow, the heat exchange capacity of the microchannel at the top of the flat tube will be significantly lower than that of the microchannel at the bottom, thus affecting the overall heat exchange effect of the microchannel heat exchanger.

[0005] Therefore, there is an urgent need for a microchannel heat exchanger with good heat exchange performance. Summary of the Invention

[0006] The purpose of this invention is to provide a microchannel heat exchanger, an air conditioner using the same, and a heat exchange method for the air conditioner, in order to solve the problems existing in the prior art. The heat exchange flat tube has several flow channels with progressively decreasing cross-sectional areas arranged from top to bottom, which increases the mass flow rate and velocity of the heat exchange medium in the top flow channel, shortens the superheated steam section, and improves the heat exchange effect of the microchannel heat exchanger.

[0007] To achieve the above objectives, the present invention provides the following solution: The present invention provides a microchannel heat exchanger, including a first manifold for flowing liquid heat exchange medium, a second manifold for flowing gaseous heat exchange medium, and a plurality of spaced heat exchange flat tubes. One end of each heat exchange flat tube is connected to the first manifold, and the other end is connected to the second manifold. The plurality of heat exchange flat tubes are located on the same horizontal plane, and a plurality of flow channels with progressively decreasing cross-sectional areas are arranged in the heat exchange flat tubes from top to bottom.

[0008] Preferably, the heat exchange flat tube is inverted trapezoidal, and the sidewall thickness of the plurality of flow channels is the same.

[0009] Preferably, the inner cavities of both the first manifold and the second manifold are cylindrical.

[0010] Preferably, the plurality of flow channels are connected to the first manifold via adapters. The adapters are provided with vertical flow channels. The top end of the vertical flow channels is connected to the first manifold, and the bottom end is closed. The side end of the vertical flow channels is connected to the plurality of flow channels in the same heat exchange flat tube via connecting holes.

[0011] Preferably, the vertical flow channel is cylindrical.

[0012] Preferably, the top of the first manifold is uniformly provided with a plurality of liquid holes for the inlet and outlet of the heat exchange medium.

[0013] The present invention also provides an air conditioner using the above-mentioned microchannel heat exchanger, comprising a heat exchange medium circulation system and the microchannel heat exchanger. The heat exchange medium circulation system includes a condenser / evaporator heat exchanger, a four-way valve, a compressor for compressing the heat exchange medium and discharging it to the microchannel heat exchanger through the four-way valve, and a gas-liquid separator for processing the heat exchange medium after operation. The four-way valve is connected to the second manifold, the condenser / evaporator heat exchanger, the compressor, and the gas-liquid separator, respectively. The gas-liquid separator is connected to the compressor, and the condenser / evaporator heat exchanger is connected to the first manifold.

[0014] Preferably, a throttle is provided between the condenser / evaporator and the first manifold, and a temperature sensor and a pressure sensor are provided between the four-way valve and the second manifold. The temperature sensor, the pressure sensor, and the throttle are all electrically connected to the control system.

[0015] The present invention also provides a heat exchange method for the above-mentioned air conditioner, comprising the following steps:

[0016] S1: When the microchannel heat exchanger is used as a condenser, the compressor supplies the gas-phase high-temperature and high-pressure heat exchange medium into the second manifold through the four-way valve. The medium condenses and releases heat in the flow channel, and is then collected by the first manifold and enters the condenser / evaporator heat exchanger to evaporate and absorb heat, forming superheated steam that flows into the gas-liquid separator through the four-way valve and then returns to the compressor to complete the cycle.

[0017] S2: When the microchannel heat exchanger is used as an evaporator, the compressor supplies high-temperature and high-pressure heat exchange medium to the condenser / evaporator through a four-way valve. After the heat exchange medium condenses and releases heat in the condenser / evaporator, it enters the flow channel through the first manifold. Since the cross-sectional area of ​​several flow channels in the same heat exchange flat tube decreases from top to bottom, the flow velocity and mass flow rate of the heat exchange medium in the upper flow channel are increased, the length of the superheated steam section in the upper flow channel is reduced, and the heat exchange effect is improved. The heat exchanged gaseous heat exchange medium passes through the second manifold, the four-way valve and the gas-liquid separator in sequence before returning to the compressor.

[0018] The present invention achieves the following technical effects compared to the prior art:

[0019] 1. In this invention, the cross-sectional areas of several flow channels within the same heat exchange flat tube decrease sequentially from top to bottom. By increasing the cross-sectional area of ​​the upper flow channel, the uneven distribution of refrigerant mass flow rate between the upper and lower channels, caused by the pressure at the inlet of the upper flow channel being lower than that of the lower flow channel, is balanced. Due to gravity, the pressure at the liquid inlet of the flow channel is always lower at the top and higher at the bottom. Based on the increased cross-sectional area of ​​the upper flow channel, according to Darcy's formula, the pressure difference between the inlet and outlet of the flow channel is directly proportional to the square of the flow velocity and inversely proportional to the hydraulic diameter of the flow channel cross-section. It can be concluded that the flow velocity and mass flow rate of the heat exchange medium in the upper flow channel both increase. With the increased mass flow rate and flow velocity in the upper flow channel, the superheated vapor section in the upper flow channel can be effectively shortened, enabling the upper flow channel to have the ability to perform good heat exchange for a long time, thus improving the overall heat exchange effect of the microchannel heat exchanger.

[0020] 2. In this invention, the heat exchange flat tube is inverted trapezoidal, and the sidewall thickness of several flow channels is the same, which further improves the heat exchange effect of the microchannel heat exchanger.

[0021] 3. In this invention, if the inner cavities of the first and second manifolds are both cylindrical, the presence of sharp edges is reduced, the influence of sharp edges on the gas-liquid flow pattern is avoided, and the heat exchange medium is ensured to enter the flow channel in a relatively stable flow pattern. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the microchannel heat exchanger of the present invention;

[0024] Figure 2 This is a cross-sectional view of the heat exchange flat tube of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of the air conditioner of the present invention;

[0026] The components include: 1. First manifold; 2. Second manifold; 3. Heat exchange flat tube; 4. Flow channel; 5. Adapter; 6. Condenser / evaporator heat exchanger; 7. Four-way valve; 8. Compressor; 9. Gas-liquid separator; 10. Throttling device; 11. Temperature sensor; 12. Pressure sensor; 13. Flow divider; and 14. Control system. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The purpose of this invention is to provide a microchannel heat exchanger, an air conditioner using the same, and a heat exchange method for the air conditioner, in order to solve the problems existing in the prior art. The heat exchange flat tube has several flow channels with progressively decreasing cross-sectional areas arranged from top to bottom, which increases the mass flow rate and velocity of the heat exchange medium in the top flow channel, shortens the superheated steam section, and improves the heat exchange effect of the microchannel heat exchanger.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Please refer to the following: Figures 1-3As shown, a microchannel heat exchanger is provided, including a first manifold 1, a second manifold 2, and several spaced-apart heat exchange flat tubes 3. The first manifold 1 is used for flowing liquid heat exchange medium, and the second manifold 2 is used for flowing gaseous heat exchange medium. One end of each heat exchange flat tube 3 is connected to the first manifold 1, and the other end is connected to the second manifold 2. The several heat exchange flat tubes 3 are located on the same horizontal plane. Several flow channels 4 with progressively decreasing cross-sectional areas are arranged sequentially from top to bottom within each heat exchange flat tube 3. The cross-sectional areas of the flow channels 4 within the same heat exchange flat tube 3 decrease sequentially from top to bottom. By increasing the cross-sectional area of ​​the upper flow channel 4, the pressure at the inlet of the upper flow channel 4 is reduced compared to the lower flow channel 4. The uneven distribution of refrigerant mass flow rate between the upper and lower channels is caused by gravity. The pressure at the inlet of flow channel 4 is always lower at the top and higher at the bottom. Based on the increased cross-sectional area of ​​the upper flow channel 4, according to Darcy's formula, the pressure difference between the inlet and outlet of flow channel 4 is directly proportional to the square of the flow velocity and inversely proportional to the hydraulic diameter of the cross-section of flow channel 4. It can be concluded that the flow velocity and mass flow rate of the heat exchange medium in the upper flow channel 4 are both increased. With the increase in mass flow rate and flow velocity in the upper flow channel 4, the superheated vapor section in the upper flow channel 4 can be effectively shortened, enabling the upper flow channel 4 to have the ability to perform good heat exchange for a long time, thus improving the heat exchange effect of the overall microchannel heat exchanger.

[0031] To further improve the heat exchange effect of the microchannel heat exchanger, the heat exchange flat tube 3 is set in an inverted trapezoidal shape, and the sidewall thickness of several flow channels 4 is the same.

[0032] The inner cavities of both the first manifold 1 and the second manifold 2 are cylindrical to reduce the presence of sharp corners and avoid their influence on the gas-liquid flow. This ensures that the heat exchange medium enters the flow channel 4 in a relatively stable flow state, avoids the impact of turbulent fluid on the wall of the flow channel 4, and improves the service life of the flow channel 4, thereby improving the service life of the microchannel heat exchanger.

[0033] To improve the uniformity of the heat exchange medium flowing in each flat tube, several flow channels 4 are connected to the first manifold 1 through adapters 5. The adapter 5 is provided with a vertical flow channel. The top of the vertical flow channel is connected to the first manifold 1 and the bottom is closed. The side of the vertical flow channel is connected to several flow channels 4 in the same heat exchange flat tube 3 through a connecting hole.

[0034] The vertical flow channel is cylindrical, also to avoid the influence of sharp edges on the gas-liquid flow pattern and to improve the service life of the microchannel heat exchanger.

[0035] The top of the first manifold 1 is uniformly provided with several liquid holes for the entry and exit of heat exchange medium. By improving the uniformity of the fluid entering the first manifold 1, and in conjunction with the adapter 5, the uniformity of the heat exchange medium flowing in each flat tube is further improved.

[0036] Several gaseous heat exchange medium inlets and outlets can be set on the second manifold 2 to increase the opening area of ​​the gaseous heat exchange medium and improve the smoothness of the gaseous heat exchange medium flow. When several gaseous heat exchange medium inlets and outlets are set, the several gaseous heat exchange medium inlets and outlets are all connected to the pipeline conveying the gaseous heat exchange medium through a distributor 13.

[0037] The present invention also provides an air conditioner using the above-mentioned microchannel heat exchanger, including a heat exchange medium circulation system and a microchannel heat exchanger. The heat exchange medium circulation system includes a condenser / evaporator heat exchanger 6, a four-way valve 7, a compressor 8 for compressing the heat exchange medium and discharging it to the microchannel heat exchanger through the four-way valve 7, and a gas-liquid separator 9 for processing the heat exchange medium after operation. The four-way valve 7 is connected to the second manifold 2, the condenser / evaporator heat exchanger 6, the compressor 8, and the gas-liquid separator 9, respectively. The gas-liquid separator 9 is connected to the compressor 8, and the condenser / evaporator heat exchanger 6 is connected to the first manifold 1.

[0038] A throttle 10 is installed between the condenser / evaporator heat exchanger 6 and the first manifold 1. A temperature sensor 11 and a pressure sensor 12 are installed between the four-way valve 7 and the second manifold 2. The temperature sensor 11, the pressure sensor 12, and the throttle 10 are all electrically connected to the control system 14. The temperature sensor 11 and the pressure sensor 12 transmit the collected temperature and pressure information to the control system 14. The control system 14 controls the channel size of the throttle 10 according to the information.

[0039] The present invention also provides a heat exchange method for the above-mentioned air conditioner, comprising the following steps:

[0040] S1: When the microchannel heat exchanger is used as a condenser, the compressor 8 supplies the gas-phase high-temperature and high-pressure heat exchange medium into the second manifold 2 through the four-way valve 7. The medium condenses and releases heat in the flow channel 4, and is then collected by the first manifold 1 and enters the condenser / evaporator heat exchanger 6 to evaporate and absorb heat, forming superheated steam that flows into the gas-liquid separator 9 through the four-way valve 7 and then returns to the compressor 8 to complete the cycle.

[0041] S2: When the microchannel heat exchanger is used as an evaporator, the compressor 8 supplies high-temperature and high-pressure heat exchange medium to the condenser / evaporator heat exchanger 6 through the four-way valve 7. After the heat exchange medium condenses and releases heat in the condenser / evaporator heat exchanger 6, it enters the flow channel 4 through the first manifold 1. Since the cross-sectional area of ​​several flow channels 4 in the same heat exchange flat tube 3 decreases from top to bottom, the flow rate and mass flow rate of the heat exchange medium in the upper flow channel 4 are increased, the length of the superheated steam section in the upper flow channel 4 is reduced, and the heat exchange effect is improved. After heat exchange, the gaseous heat exchange medium passes through the second manifold 2, the four-way valve 7 and the gas-liquid separator 9 in sequence, and then returns to the compressor 8.

[0042] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0043] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0044] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A heat exchange method for an air conditioner using a microchannel heat exchanger, characterized in that, The system includes a heat exchange medium circulation system and the microchannel heat exchanger. The heat exchange medium circulation system includes a condenser / evaporator heat exchanger, a four-way valve, a compressor for compressing the heat exchange medium and discharging it to the microchannel heat exchanger through the four-way valve, and a gas-liquid separator for treating the heat exchange medium after it has been used. The microchannel heat exchanger is a horizontal flow microchannel heat exchanger, comprising a first manifold for flowing liquid heat exchange medium, a second manifold for flowing gaseous heat exchange medium, and several spaced-apart heat exchange flat tubes. One end of each heat exchange flat tube is connected to the first manifold, and the other end is connected to the second manifold. The several heat exchange flat tubes are located on the same horizontal plane and are perpendicular to the horizontal plane. Several flow channels with progressively decreasing cross-sectional areas are arranged sequentially from top to bottom within each heat exchange flat tube. The heat exchange flat tubes are inverted trapezoidal in shape, and the sidewall thickness of the flow channels is the same. The first and second manifolds are horizontally arranged. The four-way valve is connected to the second manifold, the condenser / evaporator heat exchanger, the compressor, and the gas-liquid separator, respectively. The gas-liquid separator is connected to the compressor, and the condenser / evaporator heat exchanger is connected to the first manifold. The heat exchange method of an air conditioner includes the following steps: S1: When the microchannel heat exchanger is used as a condenser, the compressor supplies the gas-phase high-temperature and high-pressure heat exchange medium into the second manifold through the four-way valve. The medium condenses and releases heat in the flow channel, and is then collected by the first manifold and enters the condenser / evaporator heat exchanger to evaporate and absorb heat, forming superheated steam that flows into the gas-liquid separator through the four-way valve and then returns to the compressor to complete the cycle. S2: When the microchannel heat exchanger is used as an evaporator, the compressor supplies high-temperature and high-pressure heat exchange medium to the condenser / evaporator through a four-way valve. After the heat exchange medium condenses and releases heat in the condenser / evaporator, it enters the flow channel through the first manifold. Since the cross-sectional area of ​​several flow channels in the same heat exchange flat tube decreases from top to bottom, the flow velocity and mass flow rate of the heat exchange medium in the upper flow channel are increased, the length of the superheated steam section in the upper flow channel is reduced, and the heat exchange effect is improved. The heat exchanged gaseous heat exchange medium passes through the second manifold, the four-way valve and the gas-liquid separator in sequence before returning to the compressor.

2. The heat exchange method for an air conditioner using a microchannel heat exchanger according to claim 1, characterized in that, The inner cavities of both the first and second manifolds are cylindrical.

3. The heat exchange method for an air conditioner using a microchannel heat exchanger according to claim 1, characterized in that, Several of the flow channels are connected to the first manifold via adapters. The adapters are provided with vertical flow channels. The top of the vertical flow channels is connected to the first manifold, and the bottom is closed. The side of the vertical flow channels is connected to several of the flow channels in the same heat exchange flat tube through a connecting hole.

4. The heat exchange method for an air conditioner using a microchannel heat exchanger according to claim 3, characterized in that, The vertical flow channel is cylindrical.

5. The heat exchange method for an air conditioner using a microchannel heat exchanger according to claim 3, characterized in that, The top of the first manifold is uniformly provided with several liquid holes for the inlet and outlet of the heat exchange medium.

6. The heat exchange method for an air conditioner using a microchannel heat exchanger according to claim 1, characterized in that, A throttle is provided between the condenser / evaporator and the first manifold, and a temperature sensor and a pressure sensor are provided between the four-way valve and the second manifold. The temperature sensor, the pressure sensor, and the throttle are all electrically connected to the control system.

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