CN107490215B

CN107490215B - Injection structure for flooded evaporator and flooded evaporator

Info

Publication number: CN107490215B
Application number: CN201710720002.1A
Authority: CN
Inventors: 刘彩赢; 桂涛; 吴一梅; 林海佳; 尚瑞
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2017-08-21
Filing date: 2017-08-21
Publication date: 2023-06-27
Anticipated expiration: 2037-08-21
Also published as: CN107490215A

Abstract

The utility model relates to a spray structure and flooded evaporator for flooded evaporator, flooded evaporator includes the casing be provided with the heat exchange tube in the casing, still include refrigerant entry and refrigerant export, the refrigerant export sets up on the casing, spray structure includes the refrigerant runner pipe, the refrigerant entry sets up on the refrigerant runner pipe, be used for to the liquid refrigerant of refrigerant runner pipe internal input, the refrigerant runner pipe includes injection portion, injection portion is used for with liquid refrigerant injection to the casing is inside. Therefore, a liquid film and bubbles formed when the surface of the heat exchange tube is evaporated can be damaged, heat transfer resistance is reduced, heat exchange of the refrigerant at the side of the heat exchange tube is enhanced, and separated and layered refrigerating oil is mixed with the refrigerant, so that the refrigerating oil is easily sucked back to the compressor.

Description

Injection structure for flooded evaporator and flooded evaporator

Technical Field

The invention relates to the technical field of heat exchangers, in particular to a jet structure for a flooded evaporator and the flooded evaporator.

Background

There is a trend in the air conditioning chiller manufacturing industry to replace dry evaporators with flooded evaporators, which have a high surface heat transfer coefficient relative to dry evaporators due to the liquid wetting of the evaporator tube surfaces. However, the flooded evaporator has a hydrostatic column and a phenomenon of separation of refrigerant and refrigerating oil under the condition of low evaporation temperature, and oil return is difficult for the flooded evaporator, although a plurality of oil return measures and technologies exist at present, the refrigerating oil separated by the evaporator cannot be completely and thoroughly returned to the compressor, when a unit is used and operated for a period of time, the oil content in the flooded evaporator can reach a dynamic balance state, and the oil content storage in the flooded evaporator is relatively high (due to a certain volume of the flooded evaporator), so that the performance of the evaporator is affected. According to the test results published at home and abroad, when the content of the synthetic refrigerating machine oil in the flooded evaporator reaches 1%, the refrigerating capacity can be reduced by 18%. The main reason is that the surface and the nearby area of the tube are diffused by the frozen oil due to the existence of the oil, so that on one hand, the direct contact area of the refrigerant and the surface of the heat exchange tube is reduced to influence the evaporation heat absorption, and on the other hand, the flow intensity of the refrigerant evaporated in the nearby area of the tube wall is reduced, thereby reducing the heat exchange between the refrigerant and the water, and the evaporation heat exchange process of the refrigerant outside the tube is increased in heat transfer resistance, thereby reducing the heat exchange performance.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a liquid-filled evaporator injection structure capable of improving the fluid flow severity in the liquid-filled evaporator, and a liquid-filled evaporator provided with the injection structure, wherein the injection structure can improve the heat exchange performance of the liquid-filled heat exchanger and is advantageous for recovering the refrigerant oil in the evaporator.

According to a first aspect of the present application, there is provided an injection structure for a flooded evaporator, the flooded evaporator comprising a housing, a heat exchange tube being provided in the housing, and further comprising a refrigerant inlet and a refrigerant outlet, the refrigerant outlet being provided on the housing, the injection structure comprising a refrigerant flow tube, the refrigerant inlet being provided on the refrigerant flow tube for inputting a liquid refrigerant into the refrigerant flow tube, the refrigerant flow tube comprising an injection portion for injecting the liquid refrigerant into the housing.

Preferably, the refrigerant flowing pipe comprises a drainage part and the injection part, the drainage part is connected with the injection part, and the refrigerant inlet is communicated with the drainage part.

Preferably, the injection part is disposed perpendicular to the heat exchange tube.

Preferably, one or more injection parts are provided in the direction in which the heat exchange tube extends, each injection part being connected to the drainage part.

Preferably, the plurality of the injection parts are provided, and the distances from the fluid inlet ends of the plurality of injection parts to the refrigerant inlet in the extending direction of the heat exchange tube are equal.

Preferably, a nozzle is provided on the ejection portion.

Preferably, the nozzles comprise a first nozzle and/or a second nozzle, wherein,

the injection direction of the first nozzle is parallel to the heat exchange tube and is used for forming induced flow in the shell;

the jet direction of the second nozzle is perpendicular to the heat exchange tube and is used for forming secondary circulation.

Preferably, the second nozzles are disposed on both sides of the first nozzle on the same ejection portion, and the second nozzles on both sides are symmetrically disposed.

Preferably, the internal flow passage of the nozzle is conical, and the small end of the conical shape is located on the fluid ejection side.

Preferably, the length L1 of the nozzle in the refrigerant flow direction is 1-1.5 times the diameter D1 of the conical small end, and/or the cone angle A of the conical shape is 50-30 degrees.

Preferably, the inner cavity of the housing has a circular cross section, and the injection part is inserted into the housing in a radial direction of the housing.

Preferably, the drainage portion includes a plurality of branches, one end of each branch is connected together, an end connected together is communicated with the refrigerant inlet, and the other end of each branch is connected with one end of the injection portion.

Preferably, the drainage portion comprises two branches,

the two branches are arranged on a straight line, or a certain included angle is formed between the two branches; and/or the number of the groups of groups,

the two branches are symmetrically arranged with the refrigerant inlet as the center.

Preferably, the two branches and the two injection portions connected to the two branches are disposed on the same plane.

According to a second aspect of the present application, there is provided a flooded evaporator, comprising a housing, a refrigerant inlet and a refrigerant outlet, and further provided with the above-mentioned injection structure, wherein the injection structure is used for introducing a liquid refrigerant into the housing.

Preferably, the refrigerant outlet is disposed at an upper end of the housing and directed upward, the refrigerant inlet is disposed on the injection structure, and the refrigerant inlet is disposed at a lower side of the housing.

In this application, in flooded evaporator and the injection structure, through set up injection portion on the refrigerant runner pipe, with liquid refrigerant with the mode input of injection in the casing for liquid refrigerant is in the surface formation complex violent flow of heat exchange tube, destroys liquid film and bubble that forms when the heat exchange tube surface evaporates, also breaks away and is spreading the frozen oil at the surface of heat exchange tube and near the region and disturbance, has reduced heat transfer thermal resistance, thereby has strengthened the heat transfer of refrigerant at the heat exchange tube side, and also makes the frozen oil and the refrigerant mixture of layering after the separation, does benefit to the frozen oil and absorbs back the compressor. Further, by generating longitudinal induced flow and transverse secondary flow in the shell, complex and severe flow is formed on the surface of the heat exchange tube.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of the overall structure of a flooded evaporator in the present application;

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is a schematic view of the longitudinal flow of refrigerant in the flooded evaporator of the present application;

FIG. 4 is a schematic view of the secondary circulation of the refrigerant in the flooded evaporator of the present application;

fig. 5 is a schematic view of the nozzle structure in the present application.

Reference numerals in the drawings are as follows:

the flooded evaporator 100, the housing 1, the refrigerant inlet 11, the refrigerant outlet 12, the housing body 10, the end cover 101, the heat exchange tube 13, the cold water inlet 102, the cold water outlet 103, the injection structure 2, the refrigerant flow tube 21, the nozzle 22, the drainage portion 211, the injection portion 212, the first nozzle 221, the second nozzle 222, the branch 2111, the penetration portion 2121, and the insertion end 2122.

Detailed Description

The present invention is described below based on examples, but the present invention is not limited to only these examples.

The existing flooded evaporator reaches balance along with the operation of the system, the temperature of the evaporator is generally lower, so that the refrigerant in the evaporator is separated from the refrigerant oil, and the evaporation effect on the refrigerant side is poor due to the existence of the refrigerant oil. The invention provides a flooded evaporator which is provided with a jet structure, so that secondary circulation is formed on the transverse vertical surface of a heat exchange tube, and through the intensified flow, disturbance and secondary circulation, films and bubbles formed during evaporation on the surface of the heat exchange tube are destroyed, and an oil film formed on the surface of the heat exchange tube is destroyed by precipitation separation of frozen oil, so that heat exchange is intensified.

Specifically, as shown in fig. 1-2, the flooded evaporator 100 in the present application includes a housing 1, and further includes a refrigerant inlet 11 and a refrigerant outlet 12 for inputting and outputting a refrigerant, respectively. Wherein, the housing 1 includes a housing body 10 and end caps 101 positioned at two ends of the housing body 10, so as to form a liquid refrigerant accommodating cavity in the housing 1, the refrigerant outlet 12 is disposed on the housing 1, preferably disposed at an upper end of the housing 1 and facing upward, so as to facilitate outputting of the gaseous refrigerant; a heat exchange tube 13 is disposed in the housing 1, and the heat exchange tube 13 is filled with a heat exchange medium, such as cold water, for heat exchange with the refrigerant in the housing 1. A cold water inlet 102 and a cold water outlet 103 are provided in the end cover 101 for inputting and outputting a heat exchange medium to and from the heat exchange tube 13, respectively. The liquid refrigerant evaporates and then exits the flooded evaporator 100 through the refrigerant outlet 12. Preferably, the flooded evaporator 100 in the present application is provided with a spray structure 2, the spray structure 2 is disposed at the lower portion of the shell 1, and the spray structure 2 is used for increasing the flow of the refrigerant in the shell 1, so that a complex and intense flow is formed on the surface of the heat exchange tube 13, a liquid film and bubbles formed during the evaporation of the surface of the heat exchange tube 13 are destroyed, the separated frozen oil diffused on the surface of the heat exchange tube 13 and the nearby area is disturbed, and the heat transfer resistance is reduced, so that the heat exchange of the refrigerant on the side of the heat exchange tube 13 is enhanced, and the separated layered frozen oil is mixed with the refrigerant, thereby being beneficial to the absorption of the frozen oil back to the compressor. At the same time, the injection structure 2 is also used for introducing liquid refrigerant into the shell 1.

As shown in fig. 1-2, the injection structure 2 includes a refrigerant flowing pipe 21 and a nozzle 22 disposed on the refrigerant flowing pipe 21, preferably, the refrigerant inlet 11 is disposed on the refrigerant flowing pipe 21 for inputting liquid refrigerant into the refrigerant flowing pipe 21. Preferably the refrigerant inlet 11 is located on the underside of the housing 1. Preferably, the refrigerant flowing tube 21 includes a drainage portion 211 and an injection portion 212, the nozzle 22 is disposed on the injection portion 212, for injecting the liquid refrigerant in the refrigerant flowing tube 21 into the housing 1, and the drainage portion 211 is connected to the injection portion 212, for inputting the liquid refrigerant into the injection portion 212. Wherein the injection part 212 is disposed perpendicular to the heat exchange tube 13, the plurality of nozzles 22 includes a first nozzle 221 having an injection direction parallel to the heat exchange tube 13, and the liquid refrigerant injected from the first nozzle 221 flows in a direction parallel to the heat exchange tube 13, so as to promote the liquid refrigerant in the housing 1 to flow in a direction parallel to the heat exchange tube 13 to form an induced flow (described in detail later); the nozzle 22 further includes a second nozzle 222 having a spraying direction perpendicular to the heat exchange tube 13, and the liquid refrigerant sprayed by the second nozzle 222 flows in a plane perpendicular to the heat exchange tube 13 to form a secondary circulation (described in detail later), and the liquid refrigerant also continuously sucks the surrounding liquid in the flowing direction, so as to accelerate the flow of the liquid refrigerant in the housing 1.

In a preferred embodiment, the cross-section of the cavity of the housing 1 is circular, as shown in fig. 1-2. Depending on the size of the flooded evaporator 100, one or more of the ejector sections 212 may be provided in the direction in which the heat exchange tube 13 extends, and in the case where only one of the ejector sections 212 is provided, the structure of the drainage section 211 is not particularly limited, and one end thereof is the refrigerant inlet 11, and the other end thereof is connected to the ejector section 212, so long as the liquid refrigerant can be introduced into the ejector section 212. In the case where the injection part 212 is provided in plural in the extending direction of the heat exchange tube 13, for example, two as shown in fig. 1, the drainage part 211 includes two branches 2111, one end of each branch 2111 is connected together, and the connected ends thereof are communicated with the refrigerant inlet 11, the refrigerant inlet 11 may be directly provided at the connected ends, or a refrigerant introduction tube may be provided at the connected ends, and the refrigerant inlet 11 may be provided at the refrigerant introduction tube. The other end of each branch 2111 is connected to one end of the ejection portion 212. Preferably, the two branches 2111 are disposed on a straight line and are symmetrically disposed about the refrigerant inlet 11, that is, the fluid inlet ends of the two injection portions 212 are equally spaced from the refrigerant inlet 11 in the direction in which the heat exchange tube 13 extends, for example, are each L2. Thus, the refrigerant flowing into the flow guide portion 212 through the refrigerant inlet 11 can be uniformly distributed into the plurality of injection portions 212 and then injected through the plurality of nozzles 22. Preferably, the injection directions of all the first nozzles 221 are the same, so that induced flow can be formed in one direction, and the flow speed of the refrigerant is increased; preferably, the number of the first nozzles 221 on one spraying part 212 corresponds to the number of layers of the heat exchange tubes 13, for example, one first nozzle 221 is provided between every two layers of the heat exchange tubes 13, and at least two first nozzles 221 are provided on each spraying part 212, so that induced flow can be effectively generated. The second nozzles 222 are disposed on both sides of the injection pipe of the injection part 212, and more preferably, the second nozzles 222 disposed on both sides are symmetrically disposed, so that the flow rate of the secondary circulation formed by the refrigerant is relatively large, and the impact of the liquid refrigerant on the surface of the heat exchange pipe 13 is increased. Preferably, two second nozzles 222 are provided, one on each side of the ejection portion 212.

In a preferred embodiment, the two branches 2111 of the drainage portion 211 are arranged on a straight line and parallel to the heat exchange tube 13, and in other embodiments, the two branches 2111 of the drainage portion 211 may not be arranged on a straight line, for example, an included angle (not shown) is formed between the two branches 2111, which is more beneficial to the flow of fluid. Regardless of how the two branches 2111 are arranged, it is preferable that the two branches 2111 and the two injection portions 212 are disposed on the same plane, so that the flow of the liquid refrigerant can be facilitated, and energy loss can be avoided.

As shown in fig. 2, the injection part 212 is inserted into the housing 1 in the radial direction of the housing 1, and the distance of the injection part 212 inserted into the housing 1 may be specifically determined according to the specific case of the flooded evaporator. Specifically, the ejection portion 212 includes an insertion portion 2121 on the lower side that contacts the housing 1 and an insertion end 2122 on the free end. In a preferred embodiment the insertion end 2122 of the ejection portion 212 is arranged at a distance from the inner wall of the housing 1, and in a further embodiment the ejection portion 212 traverses the cross section of the housing 1, i.e. the ejection portion 212 is a tube located on the cross section diameter of the housing 1. The injection part 212 may be fixed by fixing the penetration part 2121 to the housing 1, for example, by welding; it is also possible to fix the insertion end 2122 to the inner wall of the housing 1; or both, as long as the spouting portion 212 can be firmly fixed to the housing 1.

As shown in fig. 3, after the liquid refrigerant is sprayed from the nozzles 22 of each spraying portion 212 at a certain flow rate in a direction parallel to the heat exchange tube 13, the pressure is low at the outlet of the nozzle 22 due to the high flow rate, so that the liquid around the nozzle 22 and on the rear side (left side in fig. 3) of the nozzle 22 is sucked up, so that the liquid around the nozzle 22 is strongly disturbed; as the refrigerant ejected from the nozzle 22 at a high flow rate flows forward (right side of fig. 3), the refrigerant in the flow direction is continuously sucked so that the turbulence of the surface of the refrigerant heat exchange tube 13 is enhanced, while the velocity at the axial center in the flow direction is gradually reduced, in order to prevent the axial center velocity from being reduced to zero, the velocity of the refrigerant ejected from the nozzle 22 on the ejection portion 212 can enter a negative pressure region (i.e., a surrounding region on the rear side of the nozzle 22 on the next ejection portion 212) caused by the nozzle 22 on the next ejection portion 212 before the velocity of the refrigerant ejected from the nozzle 22 on the ejection portion 212 falls to zero by adjusting the distance between the plurality of ejection portions 212 (the distance is twice L2 in the case where the ejection portion 212 is provided with a plurality of the heat exchange tubes 13), so that the refrigerant ejected from the nozzle 22 on the ejection portion 212 regains the power source before the kinetic energy is consumed, and the refrigerant ejected from the nozzle 22 on the ejection portion 212 is sucked together with the liquid around the nozzle 22 and flows forward; when the refrigerant sprayed by the nozzle 22 reaches the end cover, negative pressure appears around the axis flow sprayed out in the flow direction due to the spraying flow, so that the refrigerant reaching the end cover flows back to the surrounding area of the nozzle 22 again; thus, the flow caused by the negative pressure in the vicinity of the nozzle by the front and rear nozzle jet flows causes a longitudinal induced flow, as shown in the schematic diagram of the longitudinal flow of the refrigerant in fig. 3.

As shown in fig. 5, the internal flow channel of the nozzle 22 is preferably conical, and the internal dimensional relationship is shown in fig. 5, wherein the diameter D1 of the small end of the internal flow channel of the nozzle 22, i.e. the fluid discharge end, can be calculated according to the actual refrigerant flow, for example, the flow velocity of the discharged fluid is 1 m/s-3 m/s, the length L1 of the nozzle 22 in the refrigerant flow direction is preferably 1-1.5 times, preferably 1 time, and the cone angle a of the conical shape is preferably 50-30 degrees. For liquid refrigerants, such a nozzle configuration and size can provide an efficient fluid flow pattern within the liquid refrigerant.

For the process installation of the flooded evaporator 100 in the present application, the process installation process of the shell 1, the end cover 101 and the heat exchange tube 13 is the same as that of the conventional shell-tube heat exchanger, and for the process installation sequence of the injection structure 2, the injection tube of each injection part 212 is perforated with a connecting nozzle 22, for example, by welding, and then the injection tube of the injection part 212 is extended into the shell 1 from the bottom of the shell 1 of the heat exchanger, where the injection tube must enter from the bottom of the shell 1 and be located at the center of the cross section of the shell 1, so as to satisfy the effect of enhancing heat exchange; fixing the ejection portion 212; the injection portion 212 and the drainage portion 211 are then connected, for example by welding. The drainage portion 211 determines whether to support and fix the casing 1 according to the actual pipe diameter and length.

The enhanced heat exchange principle of the flooded evaporator in the invention is shown in fig. 4: in the lateral direction (the direction perpendicular to the heat exchange tube 13), the principle of negative pressure caused by the injection of the second nozzle 222 causes the surrounding liquid to flow, unlike the longitudinal direction (the direction parallel to the heat exchange tube 13), since there is only one second nozzle 222 in each direction and the housing 1 is circular in shape, the flow range of the fluid is short, and the flow direction of the fluid is divided into two (upward and downward) along the surface of the housing 1 due to the existence of inertia when the refrigerant hits the inner wall of the housing 1, thereby forming a lateral secondary circulation, as shown in fig. 4.

In the flooded evaporator, the longitudinal induced flow and the transverse secondary flow are generated, so that complex and severe flow is formed on the surface of the heat exchange tube, liquid films and bubbles formed during evaporation on the surface of the heat exchange tube are damaged, the separated refrigerating oil is diffused on the surface of the heat exchange tube and a nearby area, the heat transfer resistance is reduced, the heat transfer of a refrigerant on the side of the heat exchange tube is enhanced, the separated and layered refrigerating oil is mixed with the refrigerant, and the refrigerant is sucked back to the compressor.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

In the description of the present invention, the descriptions of the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" in the present application includes two and more.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The injection structure for the flooded evaporator comprises a shell, wherein a heat exchange tube is arranged in the shell, and the injection structure further comprises a refrigerant inlet and a refrigerant outlet, wherein the refrigerant outlet is arranged on the shell;

the injection part is arranged perpendicular to the heat exchange tube; one or more spraying parts are arranged in the extending direction of the heat exchange tube, and each spraying part is connected with the drainage part; a nozzle is arranged on the spraying part; the nozzles comprise a first nozzle and/or a second nozzle, and the injection direction of the first nozzle is parallel to the heat exchange tube and is used for forming induced flow in the shell; the jet direction of the second nozzle is perpendicular to the heat exchange tube and is used for forming secondary circulation; on the same spraying part, the second nozzles are arranged on two sides of the first nozzle, and the second nozzles on two sides are symmetrically arranged.

2. The ejector structure according to claim 1, wherein the ejector portion is provided in plural, and fluid inlet ends of the plurality of ejector portions are equidistant from the refrigerant inlet in a direction in which the heat exchange tube extends.

3. The spray structure of claim 1, wherein the nozzle has a conical internal flow passage with a small end on the fluid discharge side.

4. A spray structure according to claim 3, characterized in that the length L1 of the nozzle in the direction of the coolant flow is 1-1.5 times the diameter D1 of the conical small end, and/or the cone angle a of the conical shape is 30-50 degrees.

5. The spraying structure according to any one of claims 1 to 2, wherein the inner cavity of the housing has a circular cross section, and the spraying portion is inserted into the housing in a radial direction of the housing.

6. The ejector structure according to claim 1, wherein the flow guide portion includes a plurality of branches, one end of each branch being connected together, an end thereof being connected together in communication with the refrigerant inlet, and the other end of each branch being connected to one end of the ejector portion.

7. The spray structure of claim 6, wherein the drain comprises two branches,

8. The spray structure according to claim 7, wherein the two branches and the two spray portions connected to the two branches are disposed on the same plane.

9. A flooded evaporator comprising a housing, a refrigerant inlet and a refrigerant outlet, characterized in that a spray arrangement according to one of claims 1-8 is provided for introducing liquid refrigerant into the housing.

10. The evaporator as recited in claim 9, wherein said refrigerant outlet is provided at an upper end of the housing and is provided toward an upper side, said refrigerant inlet is provided on said injection structure, and said refrigerant inlet is provided at a lower side of said housing.