CN115585573A - Micro-channel condensation evaporator for cascade refrigeration - Google Patents

Abstract

The invention relates to a microchannel condensation evaporator for cascade refrigeration, which comprises a heat exchange unit, wherein the heat exchange unit comprises a heat exchange flat tube, and a plurality of microchannels are arranged in the heat exchange flat tube; one end of the heat exchange flat tube is positioned at the odd-numbered microchannel and communicated with the first channel, and the even-numbered microchannel is communicated with the second channel; the other end of the heat exchange flat tube is communicated with the odd-numbered micro-channel and the third channel, and the even-numbered micro-channel is communicated with the fourth channel; the first channel is in communication with a first fluid header and the second channel is in communication with a second fluid header; the third channel communicates with a third fluid header and the fourth channel communicates with a fourth fluid header. The invention utilizes the characteristic of high heat exchange coefficient of fluid in the microchannel in the condensing evaporator in the cascade refrigeration system, improves the heat exchange performance, saves more energy of the system, reduces the filling amount of refrigerant, is more environment-friendly, and has more compact structure of the condensing evaporator and cost saving.

Description

Micro-channel condensation evaporator for cascade refrigeration

Technical Field

The invention relates to a microchannel condensation evaporator for cascade refrigeration.

Background

The cascade refrigeration cycle has the advantages that the refrigeration temperature as low as-140 ℃ can be realized through the conventional vapor compression refrigeration cycle under the premise of normal pressure range and pressure ratio, and the refrigeration temperature region of the conventional system is greatly widened while the working efficiency is ensured. The cascade refrigeration system is typically comprised of two separate refrigeration systems, referred to as the high temperature stage and low temperature stage sections, respectively. The high temperature part uses middle temperature refrigerant, and the low temperature part uses low temperature refrigerant. The evaporation of the refrigerant in the high temperature part of the system is used to condense the refrigerant in the low temperature part of the system, and a condensing evaporator is used to connect the two parts, which is the evaporator of the high temperature part and the condenser of the low temperature part. The refrigerant of the low temperature portion absorbs heat to the object to be cooled in the evaporator, and transfers the heat to the refrigerant of the high temperature portion, and then the refrigerant of the high temperature portion transfers the heat to the cooling medium. The cascade refrigeration system has wide application, and the condensing evaporator is a key heat exchange component. The condensing evaporator of the cascade refrigeration system mostly adopts a flooded type or a gravity liquid supply type to realize the heat exchange between cold and hot fluids.

The existing condensing evaporators have the following disadvantages:

(1) The existing condensation evaporator has the disadvantages of complex structure, large overall dimension, large refrigerant filling amount, more material consumption and larger heat transfer temperature difference, thus leading to the reduction of heat transfer performance, the increase of the pressure ratio of a high-low temperature circulating refrigeration compressor, the reduction of the performance of a cascade refrigeration system and the increase of energy consumption;

(2) Flooded and gravity feed condensing evaporators require level control, which complicates construction and increases cost.

Therefore, it is necessary to develop a small-charge compact condenser-evaporator to improve the heat transfer efficiency of the condenser-evaporator, reduce the charge of refrigerant, reduce initial investment, and improve safety and thermal performance of the refrigeration system.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention provides the microchannel condensation evaporator for cascade refrigeration, the microchannel heat exchanger has the advantages of high heat exchange coefficient, small internal volume, small refrigerant charge, compact structure, lower cost and the like, and has a mature processing technology, and the microchannel heat exchanger is adopted as the condensation evaporator, so that the refrigerant charge can be obviously reduced, the heat exchange performance of the heat exchanger is improved, and the cost is reduced.

The technical scheme for solving the problems is as follows: a micro-channel condensation evaporator for cascade refrigeration is characterized in that:

the heat exchange unit comprises a heat exchange flat tube, a plurality of micro-channels are arranged in the heat exchange flat tube, and the micro-channels penetrate through two ends of the heat exchange flat tube;

one end of the heat exchange flat tube is positioned at the micro-channel at the odd number and communicated with the first channel, and the micro-channel at the even number is communicated with the second channel; the other end of the heat exchange flat tube is communicated with the odd-numbered micro-channel and the third channel, and the even-numbered micro-channel is communicated with the fourth channel;

the first channel is in communication with a first fluid header and the second channel is in communication with a second fluid header; the third passage is in communication with a third fluid header and the fourth passage is in communication with a fourth fluid header.

Furthermore, one end of the flat heat exchange tube extends into the first liquid cavity to divide the first liquid cavity into a first cavity and a second cavity which are independent of each other, wherein through holes are formed in the micro-channels positioned at odd-numbered positions in the first cavity to enable the micro-channels to be communicated with the first cavity, the first cavity is communicated with the first channel, through holes are formed in the micro-channels positioned at even-numbered positions in the second cavity to enable the micro-channels to be communicated with the second cavity, and the second cavity is communicated with the second channel;

the other end of the heat exchange flat tube extends into the second liquid cavity, the second liquid cavity is divided into a third cavity and a fourth cavity which are independent of each other, wherein through holes are formed in micro-channels located at odd-numbered positions in the third cavity to enable the micro-channels to be communicated with the third cavity, the third cavity is communicated with the third channel, through holes are formed in micro-channels located at even-numbered positions in the fourth cavity to enable the micro-channels to be communicated with the fourth cavity, and the fourth cavity is communicated with the fourth channel.

Furthermore, the cross-sectional area of the through hole formed in the microchannel is equal to the cross-sectional area of the microchannel, so that the resistance loss is reduced.

Further, the number of the micro-channels on the heat exchange flat tubes is even.

Furthermore, the first fluid header is a hot fluid inlet header, the third fluid header is a hot fluid outlet header, and the hot fluid flows into the first channel from the first fluid header, passes through the odd-numbered microchannels and the third channel and then flows into the third fluid header;

the fourth fluid header is a cold fluid inlet header, the second fluid header is a cold fluid outlet header, and cold fluid flows into the fourth channels from the fourth fluid header, passes through the even-numbered micro-channels and the second channels and then flows into the second fluid header.

Furthermore, the first fluid header is a hot fluid inlet header, the third fluid header is a hot fluid outlet header, and the hot fluid flows into the first channel from the first fluid header, passes through the odd-numbered microchannels and the third channel and then flows into the third fluid header;

the second fluid header is a cold fluid inlet header, the fourth fluid header is a cold fluid outlet header, and cold fluid flows into the second channels from the second fluid header, passes through the even-numbered micro-channels and the fourth channels and then flows into the fourth fluid header.

Furthermore, the number of the heat exchange units is multiple, and the heat exchange flat tubes of the heat exchange units are stacked into a column.

Furthermore, the first channel and the second channel of each heat exchange unit extend out of the first liquid cavity and then are bent at 90 degrees in opposite directions, and the third channel and the fourth channel extend out of the second liquid cavity and then are bent at 90 degrees in opposite directions.

Furthermore, the micro channels in the heat exchange flat tubes are arranged in a row; the first channel, the second channel, the third channel and the fourth channel are flat tubes, and only one channel is arranged inside the first channel, the second channel, the third channel and the fourth channel.

Further, the first channel, the second channel, the third channel and the fourth channel are all aluminum flat tubes.

The invention has the advantages that:

the invention utilizes the characteristic of high heat exchange coefficient of the fluid in the micro-channel in the condensing evaporator in the cascade refrigeration system, improves the heat exchange performance, saves more energy of the system, reduces the filling amount of the refrigerant, is more environment-friendly, and has more compact structure of the condensing evaporator and cost saving. The invention designs a structure that cold and hot fluids are respectively distributed into the adjacent micro-channels, so that the cold and hot fluids can exchange heat between the adjacent channels in the same micro-channel flat tube, and the heat exchange efficiency is improved.

Drawings

FIG. 1 is a block diagram of a microchannel condenser evaporator for cascade refrigeration as proposed in the present invention;

FIG. 2 is a block diagram of a heat exchange unit;

FIG. 3 is another directional view of a heat exchange unit;

FIG. 4 is a schematic cross-sectional view of a single heat exchange flat tube;

fig. 5 is a view showing the structure of the through hole and the inside of the cold and hot fluid inlet/outlet chamber.

Shown in the figure: 1. cold and hot fluid inlet/outlet header, 2, cold and hot fluid inlet/outlet liquid channel, 3, heat exchange flat tube, 4, cold and hot fluid inlet/outlet liquid cavity, 101, first fluid header, 102, second fluid header, 103, third fluid header, 104, fourth fluid header, 201, first channel, 202, second channel, 203, third channel, 204, fourth channel, 301, through hole.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.

Referring to fig. 1, 2 and 3, the invention provides a microchannel condensation evaporator for cascade refrigeration, which comprises a cold and hot fluid inlet/outlet header 1 and a heat exchange unit, wherein the cold and hot fluid inlet/outlet header 1 comprises a first fluid header 101, a second fluid header 102, a third fluid header 103 and a fourth fluid header 104, the heat exchange unit comprises a flat heat exchange tube 3 and a cold and hot fluid inlet/outlet channel 2, a plurality of microchannels are arranged in the flat heat exchange tube 3, and the microchannels penetrate through two ends of the flat heat exchange tube 3. The cooling and heating fluid inlet/outlet passage 2 includes a first passage 201, a second passage 202, a third passage 203, and a fourth passage 204.

One end of the flat heat exchange tube 3 is communicated with the odd-numbered micro-channel and the first channel 201, and the even-numbered micro-channel is communicated with the second channel 202; the other end of the flat heat exchange tube 3 is communicated with the odd-numbered micro-channel and the third channel 203, and the even-numbered micro-channel is communicated with the fourth channel 204. The first channels 201 communicate with the first fluid header 101 and the second channels 202 communicate with the second fluid header 102; the third passage 203 communicates with the third fluid header 103 and the fourth passage 204 communicates with the fourth fluid header 104.

The invention utilizes the characteristic of high heat exchange coefficient of fluid in the microchannel in the condensing evaporator in the cascade refrigeration system, improves the heat exchange performance, saves more energy of the system, reduces the filling amount of refrigerant, is more environment-friendly, and has more compact structure of the condensing evaporator and cost saving.

The odd-number micro-channels and the even-number micro-channels of the heat exchange flat tubes 3 are used for circulating cold and hot fluids or hot and cold fluids respectively, and the design enables the cold and hot fluids to be distributed to the structures in the adjacent micro-channels respectively, so that the cold and hot fluids can exchange heat between the adjacent channels in the same micro-channel flat tube, and the heat exchange efficiency is improved.

As a preferred embodiment of the present invention, referring to fig. 3 and 5, in order to make the micro-channels of the flat heat exchange tube 3 better communicate with the cold and hot fluid inlet/outlet channel 2, the heat exchange unit further comprises a cold and hot fluid inlet/outlet cavity 4, and the cold and hot fluid inlet/outlet cavity 4 comprises a first cavity and a second cavity.

Referring to fig. 5, one end of the flat heat exchange tube 3 extends into the first liquid cavity to divide the first liquid cavity into an upper part and a lower part, that is, a second cavity and a first cavity, which are independent from each other, and cold and hot fluids are not mixed with each other, wherein a through hole 301 is formed on a microchannel located at an odd number position in the first cavity to communicate with the first cavity, the first cavity is communicated with the first channel 201, a through hole 301 is formed on a microchannel located at an even number position in the second cavity to communicate with the second cavity, and the second cavity is communicated with the second channel 202. The other end of the flat heat exchange tube 3 extends into the second liquid cavity to divide the second liquid cavity into a third cavity and a fourth cavity which are independent from each other, cold and hot fluids cannot be mixed with each other, wherein a through hole 301 is formed in a micro channel positioned at an odd number position in the third cavity to enable the third cavity to be communicated with the third cavity, the third cavity is communicated with the third channel 203, a through hole 301 is formed in a micro channel positioned at an even number position in the fourth cavity to enable the fourth cavity to be communicated with the fourth cavity, and the fourth cavity is communicated with the fourth channel 204.

Referring to fig. 5, as a preferred embodiment of the present invention, the cross-sectional area of the through hole 301 formed in the microchannel is equal to the cross-sectional area of the microchannel, thereby reducing the resistance loss. The number of the micro-channels on the heat exchange flat tubes 3 is even.

As a preferred embodiment of the present invention, referring to fig. 1, the number of the heat exchange units is multiple, and the heat exchange flat tubes 3 of the heat exchange units are stacked in a row.

Referring to fig. 1, as a preferred embodiment of the present invention, the first channel 201 and the second channel 202 of each heat exchange unit extend from the first liquid chamber and are respectively bent at 90 ° in opposite directions, and the third channel 203 and the fourth channel 204 extend from the second liquid chamber and are respectively bent at 90 ° in opposite directions.

As a preferred embodiment of the present invention, the microchannels inside the flat heat exchange tubes 3 are arranged in a row; the first channel 201, the second channel 202, the third channel 203 and the fourth channel 204 are flat tubes, and micro-channels are not arranged in the first channel, and only one channel is arranged in the third channel.

As a preferred embodiment of the present invention, the first channel 201, the second channel 202, the third channel 203, and the fourth channel 204 are all aluminum flat tubes.

Referring to fig. 4, as a preferred embodiment of the present invention, the first fluid header 101 is a hot fluid inlet header, the third fluid header 103 is a hot fluid outlet header, and the hot fluid flows from the first fluid header 101 into the first channel 201, and flows into the third fluid header 103 through the through hole 301 corresponding to the first channel 201, the micro-channel with odd number, the through hole 301 corresponding to the third channel 203, and the third channel 203; the fourth fluid header 104 is a cold fluid inlet header, the second fluid header 102 is a cold fluid outlet header, and the cold fluid flows into the fourth channels 204 from the fourth fluid header 104, passes through the through holes 301 corresponding to the fourth channels 204, the micro channels at even number, the through holes 301 corresponding to the second channels 202, and then flows into the second fluid header 102.

The arrangement realizes countercurrent arrangement of the microchannel condensation evaporator for cascade refrigeration, heat exchange of cold and hot fluids is realized in the spaced microchannels, cold fluids are evaporated, and hot fluids are condensed.

Referring to fig. 4, as a preferred embodiment of the present invention, the first fluid header 101 is a hot fluid inlet header, the third fluid header 103 is a hot fluid outlet header, and the hot fluid flows from the first fluid header 101 into the first channel 201, and flows into the third fluid header 103 through the through hole 301 corresponding to the first channel 201, the micro-channel with odd number, the through hole 301 corresponding to the third channel 203, and the third channel 203; the second fluid header 102 is a cold fluid inlet header, the fourth fluid header 104 is a cold fluid outlet header, and the cold fluid flows from the second fluid header 102 into the second channels 202, passes through the through holes 301 corresponding to the second channels 202, the micro-channels at even number, the through holes 301 corresponding to the fourth channels 204, and then flows into the fourth fluid header 104.

The arrangement enables the micro-channel condensation evaporator for cascade refrigeration to realize downstream arrangement, heat exchange of cold and hot fluid is realized in the micro-channels at intervals, cold fluid is evaporated, and hot fluid is condensed.

The forward flow arrangement and the reverse flow arrangement are determined according to the actual use working conditions of the equipment, the average heat transfer temperature difference of the reverse flow is larger than that of the forward flow under the condition of the same inlet and outlet temperature, and the heat exchange quantity can be increased by adopting the reverse flow arrangement under the condition of the same heat exchange area. However, in the counter-flow arrangement, the maximum temperature of the cold and hot fluids is concentrated at the same end of the heat exchanger, so that the wall temperature is very high there. It can be seen that the forward flow arrangement and the reverse flow arrangement have advantages and disadvantages respectively, and are determined according to actual use working conditions in actual use. The present common cascade refrigeration regime generally suggests a counterflow arrangement.

In the actual use process of the heat exchanger, because the heat exchange between the two flows is carried out, the heat exchange with air is avoided and reduced, and therefore the shell of the whole heat exchanger is wrapped by the heat insulation material.

The microchannel condensation evaporator for cascade refrigeration can be used as an evaporative condenser and a heat regenerator, and can be used as a heat regenerator in a two-stage compression refrigeration cycle in common application occasions.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent flow transformations made by using the contents of the specification and the drawings, or applied directly or indirectly to other related systems, are included in the scope of the present invention.

Claims (10)

1. A microchannel condensation evaporator for cascade refrigeration, comprising:

the heat exchange device comprises a heat exchange unit, a first fluid collecting pipe (101), a second fluid collecting pipe (102), a third fluid collecting pipe (103) and a fourth fluid collecting pipe (104), wherein the heat exchange unit comprises a heat exchange flat pipe (3), a plurality of micro channels are arranged in the heat exchange flat pipe (3), and the micro channels penetrate through two ends of the heat exchange flat pipe (3);

one end of the heat exchange flat tube (3) is positioned at the odd-numbered micro channel and communicated with the first channel (201), and the even-numbered micro channel is communicated with the second channel (202); the other end of the heat exchange flat tube (3) is positioned at a micro-channel of an odd number and communicated with a third channel (203), and the micro-channel of an even number is communicated with a fourth channel (204);

the first channels (201) communicate with the first fluid header (101) and the second channels (202) communicate with the second fluid header (102); the third channel (203) communicates with the third fluid header (103) and the fourth channel (204) communicates with the fourth fluid header (104).

2. A microchannel condensation evaporator for cascade refrigeration as set forth in claim 1 wherein:

one end of the heat exchange flat tube (3) extends into the first liquid cavity to divide the first liquid cavity into a first cavity and a second cavity which are mutually independent, wherein through holes (301) are formed in the micro-channels positioned at odd positions in the first cavity to enable the micro-channels to be communicated with the first cavity, the first cavity is communicated with the first channel (201), through holes (301) are formed in the micro-channels positioned at even positions in the second cavity to enable the micro-channels to be communicated with the second cavity, and the second cavity is communicated with the second channel (202);

the other end of the heat exchange flat tube (3) extends into the second liquid cavity, the second liquid cavity is divided into a third cavity and a fourth cavity which are independent of each other, wherein a through hole (301) is formed in a micro channel located at an odd number position in the third cavity to enable the third cavity to be communicated with the third cavity, the third cavity is communicated with a third channel (203), a through hole (301) is formed in a micro channel located at an even number position in the fourth cavity to enable the fourth cavity to be communicated with the fourth cavity, and the fourth cavity is communicated with a fourth channel (204).

3. A microchannel condensation evaporator for cascade refrigeration as set forth in claim 2 wherein:

the cross-sectional area of the through hole (301) formed in the microchannel is equal to the cross-sectional area of the microchannel, so that the resistance loss is reduced.

4. A microchannel condensing evaporator for cascade refrigeration as recited in claim 1 wherein:

the number of the micro-channels on the heat exchange flat tubes (3) is even.

5. A microchannel condensing evaporator for cascade refrigeration according to any one of claims 1 to 4, wherein:

the first fluid header (101) is a hot fluid inlet header, the third fluid header (103) is a hot fluid outlet header, and hot fluid flows into the first channel (201) from the first fluid header (101), passes through the odd-numbered micro-channels and the third channel (203) and then flows into the third fluid header (103);

the fourth fluid header (104) is a cold fluid inlet header, the second fluid header (102) is a cold fluid outlet header, and cold fluid flows from the fourth fluid header (104) into the fourth channels (204) and through the even number of microchannels, the second channels (202) and into the second fluid header (102).

6. A microchannel condensation evaporator for cascade refrigeration as set forth in any one of claims 1 to 4 wherein:

the first fluid header (101) is a hot fluid inlet header, the third fluid header (103) is a hot fluid outlet header, and hot fluid flows into the first channel (201) from the first fluid header (101), passes through the odd-numbered micro-channels and the third channel (203) and then flows into the third fluid header (103);

the second fluid header (102) is a cold fluid inlet header, the fourth fluid header (104) is a cold fluid outlet header, and cold fluid flows into the second channels (202) from the second fluid header (102) and flows into the fourth fluid header (104) after passing through the even-numbered micro channels and the fourth channels (204).

7. A microchannel condensation evaporator for cascade refrigeration as set forth in any one of claims 1 to 4 wherein:

the number of the heat exchange units is multiple, and the heat exchange flat tubes (3) of the heat exchange units are stacked into a column.

8. A microchannel condensing evaporator for cascade refrigeration as recited in claim 7 wherein:

the first channel (201) and the second channel (202) of each heat exchange unit extend out of the first liquid cavity and then bend 90 degrees in opposite directions, and the third channel (203) and the fourth channel (204) extend out of the second liquid cavity and then bend 90 degrees in opposite directions.

9. A microchannel condensation evaporator for cascade refrigeration as set forth in claim 1 wherein:

micro channels in the heat exchange flat tubes (3) are arranged in a row; the first channel (201), the second channel (202), the third channel (203) and the fourth channel (204) are flat tubes, and only one channel is arranged inside.

10. A microchannel condensation evaporator for cascade refrigeration as set forth in claim 9 wherein:

the first channel (201), the second channel (202), the third channel (203) and the fourth channel (204) are all aluminum flat tubes.

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