EP3859165A1

EP3859165A1 - Ejector for heat recovery or work recovery system, and heat recovery or work recovery system

Info

Publication number: EP3859165A1
Application number: EP20215178.3A
Authority: EP
Inventors: Wei Zhang; Parmesh Verma
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2020-02-03
Filing date: 2020-12-17
Publication date: 2021-08-04
Also published as: CN113203216A

Abstract

An ejector (80) for a heat recovery or work recovery system, and a heat recovery or work recovery system are provided according to embodiments of the present disclosure. The ejector (80) includes: a high-pressure fluid passage (1); a suction fluid passage (2); a mixing chamber (3) in fluid communication with a high-pressure fluid passage (1) and a suction fluid passage (2) respectively; and a diffusion chamber (4) downstream of the mixing chamber (3), the diffusion chamber (4) having a diffusion chamber wall surrounding the diffusion chamber (4); wherein the diffusion chamber wall has a first position (A) and a second position (B) downstream of the first position (A) along a fluid flow direction, the first position (A) has a first diffusion angle (α), and the second position (B) has a second diffusion angle (β) smaller than the first diffusion angle (α). The ejector (80) according to the embodiment of the present disclosure is capable of restoring the pressure of fluid sufficiently and preventing the occurrence of flow separation.

Description

FIELD OF THE INVENTION

The present disclosure relates to the field of heat recovery or work recovery systems. More specifically, the present disclosure relates to an ejector for a heat recovery or work recovery system, and a heat recovery or work recovery system having such an ejector.

BACKGROUND OF THE INVENTION

In commercial heat recovery or work recovery systems, especially systems that require a large pressure differential, an ejector is used to improve efficiency. The ejector typically pressurizes a suction fluid by means of a high-pressure fluid and supplies mixed fluids to a compressor inlet, thereby increasing the pressure of fluid at the compressor inlet, reducing the requirements on the capacity of the compressor and improving the efficiency of the system.
The ejector usually includes a high-pressure fluid nozzle to convert the high-pressure fluid into a high-momentum fluid. The suction fluid is suctioned in with the high-momentum fluid and mixed with the high-momentum fluid in a mixing chamber, then diffuses in a diffusion chamber to increase the pressure of the fluid and is subsequently supplied to the compressor. A wall of the diffusion chamber has a diffusion angle. An effective recovery pressure needs to be considered and an occurrence of flow separation needs to be avoided in designing the diffusion angle. On the other hand, a length of the ejector, especially a length of the diffusion chamber, is limited by the actual application scenario.

SUMMARY OF THE INVENTION

An object of the present disclosure is to solve or at least alleviate the problems existing in the related art.
According to a first aspect of the invention, an ejector for a heat recovery or work recovery system is provided, which includes:

a high-pressure fluid passage;
a suction fluid passage;
a mixing chamber in fluid communication with a high-pressure fluid passage and a suction fluid passage respectively; and
a diffusion chamber downstream of the mixing chamber, the diffusion chamber having a diffusion chamber wall surrounding the diffusion chamber;
wherein the diffusion chamber wall has a first position and a second position downstream of the first position along a fluid flow direction, the first position has a first diffusion angle, and the second position has a second diffusion angle smaller than the first diffusion angle.

Optionally, the second diffusion angle has a positive value or a negative value.
Optionally, the first diffusion angle is between 3° and 10°, and an absolute value of the second diffusion angle is greater than or equal to 0° and smaller than an absolute value of the first diffusion angle.
Optionally, the diffusion chamber wall includes a first section and a second section, the first section has a constant diffusion angle, and the first position is taken from the first section; the second section has a constant diffusion angle, and the second position is taken from the second section.
Optionally, the first section and the second section adjoin to each other.
Optionally, the diffusion chamber wall has an arc-shaped section having a gradually decreasing diffusion angle, and the first position and the second position are both taken from the arc-shaped section.
Optionally, the diffusion chamber wall is composed of a first section having a constant diffusion angle and a second section having a constant diffusion angle, or the diffusion chamber wall is composed of an arc-shaped section having a gradually decreasing diffusion angle.
Optionally, the length D2 of the diffusion chamber is in a range of 0.8D1 to 3D1, and D1 is the length of the mixing chamber.
Optionally, the high-pressure fluid passage includes a high-pressure fluid inlet and a high-pressure fluid nozzle, the high-pressure fluid nozzle includes a constricted section, a throat portion, a diffusion section, and a high-pressure fluid outlet in sequence, and the high-pressure fluid outlet faces toward the mixing chamber; the suction fluid passage includes a suction fluid inlet and a suction chamber surrounding the high-pressure fluid nozzle, the suction chamber is in communication with the mixing chamber, and a tapered transition section is located between the suction chamber and the mixing chamber.
In another aspect, a heat recovery or work recovery system including the ejector as described herein with reference to the first aspect of the invention is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The contents of the present disclosure will become easier to understand with reference to the accompanying drawings. It can be easily understood by those skilled in the art that the drawings are provided by way of example only, and are merely used for illustration, and are not intended to limit the scope of protection of the present disclosure. In addition, like parts are denoted by like numerals in the drawings, wherein:

FIG. 1 shows a schematic view of a work recovery system;
FIG. 2 shows a schematic structural view of an ejector;
FIG. 3 shows a schematic structural view of an ejector;
FIG. 4 shows a simulated pressure comparison diagram of a single-angle ejector and an ejector according to the present disclosure; and
FIG. 5 shows a simulated speed comparison diagram of a single-angle ejector and an ejector according to the present disclosure.

DETAILED DESCRIPTION

Referring to FIG. 1, a work recovery system to which an ejector is applied will be described. An example will be used in which the work recovery system is a refrigeration device. The work recovery system may include a compressor 83, an outlet of the compressor 83 is connected to an inlet of a condenser 82 downstream thereof, and an outlet of the condenser 82 is connected to a high-pressure fluid inlet 11 of an ejector 80. On the other hand, a fluid outlet 43 of the ejector 80 is connected to a separator 84. A fluid exiting from the fluid outlet 43 of the ejector 80 is separated in the separator, wherein a gas phase returns to an inlet of the compressor 83, and a liquid phase passes through a valve 85 and an evaporator 86 and then arrives at a suction fluid inlet 21 of the ejector 80. In the illustrated example, the ejector 80 is used in the work recovery system as shown in FIG. 1. In an alternative example, the ejector 80 may also be applied to other types of more complicated work recovery systems. In addition, the ejector 80 may also be applied to a heat recovery system, such as a heat recovery system including a generator. In the illustrated example, the work recovery system includes only one ejector, and in alternative examples, the system may include a plurality of ejectors. Therefore, the ejector according to various examples can be applied to various types of heat recovery or work recovery systems.
With continued reference to FIG. 2, the ejector will be described. The ejector includes: a high-pressure fluid passage 1; a suction fluid passage 2; a mixing chamber 3 in fluid communication with the high-pressure fluid passage 1 and the suction fluid passage 2 respectively; and a diffusion chamber 4 downstream of the mixing chamber 3. In some examples, the high-pressure fluid channel 1 includes a high-pressure fluid inlet 11, and a high-pressure fluid nozzle which includes a constricted section 13, a throat portion 14, a diffusion section 15 and a high-pressure fluid outlet 16 in sequence, and the high-pressure fluid outlet 16 faces toward the mixing chamber 3. In some examples, the suction fluid passage 2 includes a suction fluid inlet 21 and a suction chamber 22 surrounding the high-pressure fluid nozzle, and the suction chamber 22 is in communication with the mixing chamber 3. In some examples, a transition section 23 between the suction chamber 22 and the mixing chamber 3 has a tapered structure. In some examples, the mixing chamber 3 may be of a cylindrical shape having an equal sectional area, and a high-pressure fluid entering the mixing chamber 3 through the high-pressure fluid passage 1 is sufficiently mixed with a suction fluid suctioned through the suction fluid passage 2 in the mixing chamber 3 to form a subsonic velocity fluid. This fluid diffuses in the diffusion chamber 4 to restore pressure from the kinetic energy therein, thereby forming a medium-pressure fluid to be supplied to for example a compressor inlet. In the design of the diffusion chamber 4, the diffusion angle needs to ensure that the fluid pressure is sufficiently restored. On the other hand, the diffusion angle should not be too large, which would otherwise cause flow separation, thereby resulting in local turbulence and fluid energy loss. In addition, the length of the diffusion chamber 4 is limited by the actual application environment, such as the size of a heat recovery or work recovery system or device. Therefore, it is desirable to provide an ejector capable of sufficiently recovering fluid pressure and as compact as possible.
In the design of the present disclosure, the diffusion chamber 4 has a diffusion chamber wall surrounding the diffusion chamber, wherein the diffusion chamber wall has a first position A and a second position B downstream of the first position A along a fluid flow direction. The first position A has a first diffusion angle α, and the second position B has a second diffusion angle β smaller than the first diffusion angle α. It should be understood that in the specification and the claims, the diffusion angle at a position in the diffusion wall refers to an angle formed between a tangent line at that position and a central line direction of the diffusion chamber in the section for example shown in FIG. 2 or 3.
In the example shown in FIG. 2, the diffusion chamber wall is composed of a first section 41 and a second section 42. The first section 41 has a constant diffusion angle, and the shape of the first section 41 is substantially a cone shape gradually diverging in the fluid direction. The first position A is taken from the first section 41. The second section 42 has a constant diffusion angle, and the second position is taken from the second section 42. Therefore, the values of the diffusion angles in any position of the first section 41 are equal to the first diffusion angle α, and the values of the diffusion angles in any position of the second section 42 are equal to the second diffusion angle β. In some examples, the first diffusion angle α is a positive value, such as in a range of 3° to 10°, such as in a range of 3° to 6°, or such as in a range of 3° to 4.5°. Alternatively, the first diffusion angle α may be 3°, 4.5°, 6°, or a range of 3° to 4.5°, or a range of 4.5° to 6°. In some examples, the diffusion angle β of the second section may be a positive value or a negative value, wherein a positive value indicates that the diffusion chamber wall gradually diverges at that angle, and a negative value indicates that the diffusion chamber wall gradually converges at that angle. In the example shown in FIG. 2, the second section 42 gradually converges at an angle value of the second diffusion angle β, that is, the second diffusion angle β is a negative value. In an alternative example, the second diffusion angle β may also be a positive value, that is, the diffusion chamber wall gradually diverges in the second section 42 at a value of the second diffusion angle β different from the first diffusion angle α. In some examples, an absolute value of the second diffusion angle β may be in a range of greater than or equal to 0° and smaller than the first diffusion angle α. In the example shown in FIG. 2, the diffusion chamber wall is composed of the first section 41 and the second section 42 with different diffusion angles from each other. In an alternative example, the diffusion chamber wall may have more sections. For example, it may have a third section downstream of the second section in the fluid flow direction. The third section is also a section having a constant diffusion angle, and it has a third diffusion angle smaller than the second diffusion angle, or the third section may be an arc-shaped section or the like.
In some examples, the first section 41 and the second section 42 may directly adjoin to each other, and in an alternative example, the first section 41 and the second section 42 may be separated by other sections. For example, there may be an intermediate section between the first section 41 and the second section 42, and the intermediate section may be, for example, a section having a diffusion angle of 0°. As shown in FIG. 3, an angle γ formed by a connection line of the inlet (point A) and the outlet (point C) on the diffusion chamber wall with the fluid direction may be referred to as a net diffusion angle γ of the diffusion chamber 4. In some examples, the absolute values of the first diffusion angle α and the second diffusion angle β may be both greater than the net diffusion angle γ. In some examples, one of the absolute values of the first diffusion angle α and the second diffusion angle β may be greater than the net diffusion angle γ and the other may be less than the net diffusion angle γ.
With continued reference to FIG. 3, another example of the ejector according to the present disclosure is shown. In this example, the same structure as in the previous example is not repeated. In this examples, the diffusion chamber wall includes an arc-shaped section having a gradually decreasing diffusion angle, and the first position A and the second position B are taken from the arc-shaped section. At the first position A, the first diffusion angle α is an angle formed between a tangent line L₁ at the position A and L₄ representing the center line direction, and at the second position B, the second diffusion angle β is an angle formed between a tangent line L₂ at the position B and L₅ representing the center line direction. In addition, an angle γ formed between a connection line L₃ of the diffusion chamber inlet (point A) and the diffusion chamber outlet (point C) and L₄ representing the center line direction may be referred to as the net diffusion angle. An arc-shaped section having a gradually decreasing diffusion angle means that in the arc-shaped section, the diffusion angle at any position is greater than the diffusion angle at any point downstream of said position. In the example shown in FIG. 3, the diffusion chamber wall is entirely composed of an arc-shaped section having a gradually decreasing diffusion angle. In an alternative example, the diffusion chamber wall may have other sections, such as straight sections having a certain diffusion angle in FIG. 2 or other types of arc-shaped sections. In some examples a length D2 of the diffusion chamber is in a range of 0.8D1 to 3D1, wherein D1 is a length of the mixing chamber. In an alternative example, the length D2 of the diffusion chamber may be in a range of 0.8D1 to 2D1, or in a range of 0.8D1 to 1.5D1, or in a range of 0.8D1 to 1.2D1. In some examples, the length D2 of the diffusion chamber is less than the length D1 of the mixing chamber, such as in a range of 0.7D1 to 0.9D1 or in a range of 0.8D1 to 0.9D1.
With continued reference to FIGS. 4 and 5, a simulated pressure comparison diagram and a simulated speed comparison diagram of the ejector according to the present disclosure and a conventional ejector are shown. In FIG. 4, the upper diagram shows a diffusion chamber having a constant diffusion angle of 3°, and the lower diagram shows a diffusion chamber which has a first section having a diffusion angle of 4.5° and a second section having a diffusion section of 3°, wherein a darker color indicates a greater pressure. It can be seen from the diagrams that points F and G are equal-pressure points, and it can therefore be seen that the diffusion chamber according to the present disclosure can recover to the same pressure in a shorter length. In other words, the diffusion chamber according to the present disclosure can restore the pressure of the fluid more sufficiently in a case of a diffusion zone of the same length. In FIG. 5, the upper diagram shows a diffusion chamber having a constant diffusion angle of 3°, and the lower diagram shows a diffusion chamber according to the present disclosure, which has a first section having a diffusion angle of 4.5° and a second section having a diffusion section of 3°, wherein a darker color indicates a slower speed. It can be seen from the diagrams that the diffusion chamber according to the present disclosure can obtain a lower-speed fluid (that is, a higher pressure) in a case of a diffusion zone of the same length. Therefore, in the diffusion chamber according to the present disclosure, the pressure can be restored more sufficiently through a section having a larger diffusion angle close to the inlet zone as well as a flow separation can be prevented through the subsequent section, the pressure can be sufficiently restored in a shorter distance, thereby making it adapted to a more compact use environment.
In addition, a heat recovery or work recovery system including the ejector according to the various examples herein is provided.
The specific examples described above are merely for describing the principle of the present disclosure more clearly, and various components are clearly illustrated or depicted to make it easier to understand the principle of the present disclosure. Those skilled in the art can readily make various modifications or changes to the present disclosure. Therefore, it should be understood that these modifications or changes should be included within the scope of protection of the present invention as defined by the claims.

Claims

An ejector (80) for a heat recovery or work recovery system, comprising:
a high-pressure fluid passage (1);

a suction fluid passage (2);

a mixing chamber (3) in fluid communication with the high-pressure fluid passage (1) and the suction fluid passage (2) respectively; and

a diffusion chamber (4) downstream of the mixing chamber (3), the diffusion chamber having a diffusion chamber wall surrounding the diffusion chamber;

wherein the diffusion chamber wall has a first position (A) and a second position (B) downstream of the first position along a fluid flow direction, the first position has a first diffusion angle (α), and the second position has a second diffusion angle (β) smaller than the first diffusion angle.
The ejector (80) for a heat recovery or work recovery system according to claim 1, wherein the second diffusion angle (β) has a positive value or a negative value.
The ejector (80) for a heat recovery or work recovery system according to claim 1 or 2, wherein the first diffusion angle (α) is between 3° and 10°, and an absolute value of the second diffusion angle (β) is greater than or equal to 0° and smaller than an absolute value of the first diffusion angle.
The ejector (80) for a heat recovery or work recovery system according to any one of claims 1 to 3, wherein the diffusion chamber wall comprises a first section (41) and a second section (42), the first section has a constant diffusion angle, and the first position (A) is taken from the first section; the second section has a constant diffusion angle, and the second position (B) is taken from the second section.
The ejector (80) for a heat recovery or work recovery system according to claim 4, wherein the first section (41) and the second section (42) adjoin to each other.
The ejector (80) for a heat recovery or work recovery system according to any of claims 1 to 3, wherein the diffusion chamber wall has an arc-shaped section having a gradually decreasing diffusion angle, and the first position (A) and the second position (B) are both taken from the arc-shaped section.
The ejector (80) for a heat recovery or work recovery system according to any of claims 1 to 3, wherein the diffusion chamber wall is composed of a first section (41) having a constant diffusion angle and a second section (42) having a constant diffusion angle, or the diffusion chamber wall is composed of an arc-shaped section having a gradually decreasing diffusion angle.
The ejector (80) for a heat recovery or work recovery system according to any preceding claim, wherein a length D2 of the diffusion chamber (4) is in a range of 0.8D1 to 3D1, and D1 is a length of the mixing chamber (3).
The ejector (80) for a heat recovery or work recovery system according to any preceding claim, wherein the high-pressure fluid passage (1) comprises a high-pressure fluid inlet (11) and a high-pressure fluid nozzle, the high-pressure fluid nozzle comprises a constricted section (13), a throat portion (14), a diffusion section (15), and a high-pressure fluid outlet (16) in sequence, and the high-pressure fluid outlet faces toward the mixing chamber (4); the suction fluid passage (2) comprises a suction fluid inlet (21) and a suction chamber (22) surrounding the high-pressure fluid nozzle, the suction chamber is in communication with the mixing chamber (4), and a tapered transition section (23) is located between the suction chamber and the mixing chamber.
A heat recovery or work recovery system, comprising the ejector (80) according to any one of claims 1 to 9.