JP2004076742A - Method of improving efficiency of ejector and method of suppressing effective energy loss of ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress effective energy loss and improve the efficiency of an ejector by using the ejector in relatively simple construction for giving a non-steady flow to a primary fluid (high energy fluid) so that an interface between the primary fluid (the high energy fluid) and a second fluid (a low energy fluid) is almost perpendicular to the flowing direction of the fluid. <P>SOLUTION: The ejector is used for giving the non-steady flow to the primary fluid so that the interface between the primary fluid and the secondary fluid is almost perpendicular to the axial direction of the ejector. Energy exchange between both fluids is performed by pressure exchange between the primary and secondary fluids in direct contact with each other, while reducing the effective energy loss with the non-steady flow of the primary fluid. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method of improving the efficiency of an ejector and a method of suppressing an effective energy loss of an ejector in which the flow of a primary fluid is made to be an unsteady flow, particularly in the field of an ejector subjected to vacuum generation, compression, pressure increase, and the like.

As shown in FIG. 9, a conventional ejector includes a nozzle 100 and a diffuser 102, injects a low-pressure secondary fluid by injecting a primary fluid at a high speed from the nozzle 100, and draws a secondary fluid between the primary fluid and the secondary fluid. The pressure is discharged from the diffuser 102 with pressure conversion (energy exchange). When a refrigeration cycle is configured using an ejector, an evaporator containing the secondary fluid in a liquid phase is connected to an ejector, and the heat of vaporization generated when the secondary fluid is evaporated and sucked. (Cold heat generated by (evaporative latent heat)) is used.
In the conventional ejector, the primary fluid and the secondary fluid are mixed and sheared by the primary fluid at the interface 104 where the primary fluid and the secondary fluid are in contact with each other. Based on the turbulence in the boundary region between the two fluids due to the difference and the entrainment due to the vortex, an increase in entropy, that is, a loss of effective energy has been inevitable. Further, since the primary fluid in the high energy state and the secondary fluid in the low energy state are directly mixed, the loss of the effective energy has been inevitable here. Due to these factors, conventional ejectors have been very inefficient.

In order to suppress the loss of effective energy and improve the efficiency of the ejector, when the high-energy fluid and the low-energy fluid are in direct contact, the interface between the two fluids must be perpendicular to their flow direction. desirable. In other words, it is desirable that the fluid flows in the normal direction of the interface between the two fluids. In this state, transfer of energy (pressure) is reversibly performed via the interface between the fluids in a state where the two fluids do not mix as much as possible. Further, the high-energy fluid and the low-energy fluid exchange energy via the interface, and are mixed after being in a substantially same energy state. For this reason, the effective energy loss at the time of suction / mixing is significantly reduced as compared with the case of shearing.
Such a state in which the interface between the high-energy fluid and the low-energy fluid is perpendicular to the direction of their flow cannot be realized when the primary fluid jet flows constantly as in a conventional ejector. It is.

For example, the ejector disclosed in Patent Literature 1 provides one measure for realizing the above state. FIG. 10 is a cross-sectional view of the ejector shown in the document. In FIG. 10, 110 is a primary fluid supply pipe, 111 is a secondary fluid supply pipe, 112 is a nozzle attached to the tip of the primary fluid supply pipe 110, 113 is a diffuser, and 114 is a nozzle facing the nozzle 112 so as to be rotatable. The conical rotor provided has a plurality of blades 115 mounted on the conical surface thereof. Reference numeral 116 denotes a shaft for supporting the rotor 114, and 117 denotes a spindle concentrically fixed in the diffuser 113, which is a spindle-shaped member for supporting the rotor 114 on a concentric axis.
U.S. Patent No. 6,138,456

In this ejector, a conical rotor 114 which rotates freely with extremely low friction is disposed opposite to an injection port of a nozzle 112, and a plurality of inclined blades 115 are provided on a conical surface of the rotor 114. The rotor 114 with 115 is coaxially supported in the diffuser 113. According to the configuration of the ejector, the jet of the primary fluid from the nozzle 112 acts on the blade 115 attached to the rotor 114, and the rotor 114 rotates freely. A helical flow of the primary fluid is formed downstream of the rotating rotor 114 across the blades 115. The velocity component of this spiral flow has a large velocity component in the ejector axial direction. The secondary fluid is held between the spirals of this primary fluid helical flow and transported as if pressed by a helically shaped piston. At this time, since the interface between the primary fluid and the secondary fluid is not parallel to the velocity direction of the fluid, but has an angle according to the strength of the helix, it approaches the phenomenon of a volume pump, and the conventional method involving winding by shearing , The increase in entropy, that is, the loss of effective energy can be reduced. Furthermore, since the primary fluid and the secondary fluid exchange energy (pressure) through their interfaces and become approximately equi-energy, they are mixed, which is more effective than when fluids with different energy states are directly mixed. Energy loss can be suppressed. These effects improve the efficiency of the ejector. The helical flow of the primary and secondary fluids is called "non-steady flow". Here, the unsteady flow refers to a flow in which a state such as a flow rate, a speed, a pressure, and a temperature temporally and spatially changes.

As described above, the ejector of Patent Document 1 generates an unsteady spiral flow of the primary fluid, thereby improving the efficiency of the ejector.
However, in this ejector, it is necessary to install a freely-rotating bladed rotor downstream of the nozzle, so that the ejector structure is more complicated than that of the conventional one, and the rotating shaft of the rotating body and the bearing, Maintenance is required due to the durability of the device. Further, there is a problem that the interface between the primary fluid and the secondary fluid cannot be vertical to the velocity direction of the fluid. In order for the primary fluid and the secondary flow to exchange energy (pressure) through the interface most efficiently, it is desirable that the interface be perpendicular to the velocity direction of the fluid. This is because if the interface is not perpendicular to the speed direction, entrainment due to shearing due to the speed component in the direction parallel to the interface occurs, and the efficiency is reduced. In the spiral flow of Patent Document 1, the strength of the spiral can be adjusted by adjusting the blade mounting angle of the bladed rotor. By making the blade mounting angle close to the vertical direction with respect to the primary fluid jet velocity direction, it is possible to make the angle of the primary fluid / secondary fluid interface with respect to the velocity direction close to vertical, but it cannot be true vertical. Further, making the blade mounting angle perpendicular to the primary fluid jet velocity direction becomes a resistance to the primary fluid flow, and lowers the efficiency in another sense.

The present invention has been made in order to solve such a problem, and makes the primary fluid (high-energy fluid) an unsteady flow by using an ejector having a relatively simple configuration. By making the interface of the secondary fluid (low-energy fluid) almost vertical to the fluid flow direction, it is possible to suppress the loss of effective energy and improve the efficiency of the ejector. And a method for suppressing the effective energy loss of the ejector.

The method for improving the efficiency of an ejector according to the present invention is characterized in that, when performing energy exchange between a high-energy fluid and a low-energy fluid by pressure contact between the two fluids inside the ejector, the high-energy fluid is made into an unsteady flow Thus, the loss of effective energy is reduced.

Further, the method for suppressing the effective energy loss of the ejector according to the present invention is characterized in that the energy exchange between the two fluids is performed by the pressure exchange by direct contact between the high energy fluid and the low energy fluid inside the ejector. Is characterized by making the high-energy fluid unsteady flow so as to be substantially perpendicular to the ejector axis direction.

Here, the ejector according to the present invention is an ejector that sucks and / or pressurizes a low-energy fluid (hereinafter, referred to as “secondary fluid”) by a jet of a high-energy fluid (hereinafter, referred to as “primary fluid”). An unsteady flow of the primary fluid is generated such that the interface between the fluid and the secondary fluid is substantially perpendicular to the ejector axis direction. It should be noted that the term “interface” as used herein does not necessarily mean a boundary having a clear boundary but also a transition layer.

In the method for improving the efficiency of the ejector or the method for suppressing the effective energy loss of the ejector according to the present invention, the form of the unsteady flow is an intermittent flow or a pulsating flow.
Here, the “intermittent flow” refers to a flow in which the fluid intermittently flows in one direction, and there is a moment when the flow rate of the fluid becomes zero. “Pulsating flow” refers to a form in which the flow rate of a fluid fluctuates in the main flow direction with time, and does not become 0 even at the moment when the flow rate becomes minimum.
By using such an intermittent flow or a pulsating flow, it is possible to generate an unsteady flow of the primary fluid without rotating or rotating the rotor or the like. The secondary fluid is sandwiched and held between the primary fluid masses, and the interface between the two fluids is substantially perpendicular to the flow direction of the fluid.

The unsteady flow of the primary fluid as described above includes (1) periodic heating control of the inner pipe provided in the primary fluid supply pipe, (2) periodic supply control of the primary fluid supply device, and (3) primary fluid. It can be generated by any of the following methods: periodic flow control of the supply control device, and (4) periodic application control of a high electric field to the primary fluid heating device.

In the method (1), the liquid in the inner pipe is evaporated by periodically heating the inner pipe provided in the primary fluid supply pipe, and the liquid is discharged by the bubbles. This is guided to the nozzle, and the primary fluid in the gas phase is ejected from the nozzle tip, whereby an unsteady flow of the primary fluid can be generated.

In the method (2), an intermittent extrusion type device such as a diaphragm pump is used as a primary fluid supply device, and this is periodically controlled.

In the method (3), for example, an electromagnetic valve or the like is used as the primary fluid supply control device, and this is periodically controlled to open and close.

In the method (4), for example, an insulating coating electrode is provided in the primary fluid heating device, and a high electric field is periodically applied to the electrode to intermittently increase or decrease the evaporation amount of the primary fluid in the heating device. Things.

な As is clear from the above, the ejector of the present invention has no rotating body such as a rotor inside the ejector, has a relatively simple structure, and is low in cost.

冷凍 Further, by configuring a refrigeration cycle using the ejector according to the present invention, a refrigeration system can be configured.

By using the ejector according to the present invention, the primary fluid can be unsteady flow and the interface with the secondary fluid can be vertical in the flow direction, the effective energy loss at the time of suction and mixing of the secondary fluid is reduced, The efficiency of the ejector is improved. In other words, the flow rate ratio of the secondary fluid to the primary fluid (= [secondary fluid flow rate] / [primary fluid flow rate]) increases, and the amount of primary fluid required to suction a unit amount of secondary fluid is reduced. . By the way, in comparison with the refrigeration system using the conventional example of FIG. 9, in the present invention, the amount of the primary fluid required to suck the same amount of the secondary fluid is reduced to 1/3 or less, that is, the efficiency is 3 times or more. To improve.

As described above, by using the ejector according to the present invention, when performing energy exchange between the two fluids by pressure exchange by direct contact between the primary fluid and the secondary fluid inside the ejector, the primary fluid is regarded as an unsteady flow. And thereby the loss of effective energy can be reduced, which has the effect of greatly improving the efficiency of the ejector.
Also, when performing energy exchange between the two fluids by pressure exchange by direct contact between the primary fluid and the secondary fluid inside the ejector, the primary fluid is set so that the interface between the two fluids is substantially perpendicular to the ejector axis direction. Can be made into an unsteady flow, so that there is an effect that loss of effective energy of the ejector can be suppressed.

Hereinafter, an embodiment of an ejector used in the method of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a diagram showing an outline of an ejector according to Embodiment 1 of the present invention.
The ejector 1 mainly includes a nozzle 2 and a diffuser 3 in which the nozzle 2 is arranged concentrically. The diffuser 3 has an inlet 4 on the upstream side, and the nozzle 2 is attached to the tip of a primary fluid supply pipe 5 passing through the inlet 4. The nozzle 2 is connected to a primary fluid supply device 7 composed of a pump or the like via a primary fluid heating device 6 via a primary fluid supply pipe 5, and a secondary fluid supply pipe is connected to the introduction section 4 of the diffuser 3. A secondary fluid supply unit 9 which is a supply source of the secondary fluid is connected via 8. The diffuser 3 is connected to another process, a condenser, the atmosphere, or the like via an outflow pipe 10.

FIG. 1 shows an example of an unsteady flow generating means for a primary fluid in which an inner pipe is constituted by a group of thin tubes 11. The group of small tubes 11 is installed on the upstream side inside the primary fluid supply pipe 5 and connected to the primary fluid heating device 6. As shown in FIG. 2, the thin tube group 11 has a structure in which a plurality of thin tubes 12 are bundled, and a heating means 13 is provided at the tip of each thin tube 12. The heating means 13 is, for example, an electric heater and heats the thin tube 12 periodically and instantaneously.

FIG. 3 schematically shows the primary fluid discharge phenomenon when the thin tube 12 is heated by the heating means 13. That is, when the primary fluid in the superheated liquid phase state is filled in the thin tube 12 after passing through the primary fluid heating device 6, when the heating means 13 instantaneously heats the liquid, a part of the liquid evaporates. When the evaporated bubbles 14 expand at a stretch, the heating liquid existing on the tip side of the heating unit 13 in the thin tube 12 is pushed out from the thin tube 12. The extruded heating liquid droplets 15 reach the nozzle 2 while evaporating and expanding, and are ejected from the nozzle 2 at a high speed. The number of the thin tubes 12 in the thin tube group 11 may be an arbitrary number according to the flow rate of the primary fluid.

Thus, by intermittently repeating the instantaneous heating by the heating means 13, an intermittent primary fluid flow is generated. FIG. 4 illustrates a situation where the intermittent primary fluid flow is generated inside the ejector 1. Due to the intermittent primary fluid flow, the primary fluid mass 16 flows to the right in FIG. 4, the secondary fluid is sucked between the primary fluid masses 16 and the secondary fluid mass 17 is formed, and also to the right. Flow. The interface between the primary fluid mass 16 and the secondary fluid mass 17 is substantially perpendicular to the flow direction of the fluid mass, and energy is transferred between the primary fluid mass 16 and the secondary fluid mass 17. After the transfer of the energy, the primary fluid mass 16 and the secondary fluid mass 17 that have become substantially the same energy state are mixed, and flow out to the outflow pipe 10 while the velocity energy is restored to the pressure energy by the diffuser 3. Therefore, the energy transfer between the primary fluid mass 16 and the secondary fluid mass 17 is performed through the vertical interface, and the fluids are mixed after the energy states of both fluids are close to each other. Efficiency is improved.
The heating means 13 can use the electric heater as described above and apply the pulse current to the electric heater periodically to provide the above function. However, the heating means other than the electric heater is intermittently used. Each thin tube 12 may be heated.

Embodiment 2 FIG.
FIG. 5 is a schematic diagram of an ejector according to Embodiment 2 of the present invention. In this embodiment, another example of a means for generating an unsteady flow of a primary fluid is shown in place of the capillary group 11 as shown in FIG. Is used to generate an intermittent or pulsating primary fluid flow. Examples of such a primary fluid supply device 7 include a diaphragm pump and a tube pump.

Embodiment 3 FIG.
FIG. 6 is a schematic diagram of an ejector according to Embodiment 3 of the present invention. In this embodiment, unlike the second embodiment, a primary fluid supply control device 18 is provided between the primary fluid supply device 7 and the primary fluid heating device 6, and the primary fluid supply control device 18 To generate an intermittent flow or a pulsating flow in the flow. An example of such a primary fluid supply control device 18 is a solenoid valve. In FIG. 6, the primary fluid supply control device 18 is installed between the primary fluid supply device 7 and the primary fluid heating device 6, but is located downstream of the primary fluid heating device 6 and upstream of the primary fluid supply device 7. It can be installed at any position such as the side.

Embodiment 4 FIG.
FIG. 7 is a schematic diagram of an ejector according to Embodiment 4 of the present invention. This embodiment aims at a method referred to as the so-called "Asakawa effect" as still another example of the means for generating the unsteady flow of the primary fluid. That is, the primary fluid heating device 6 has a heat exchanger 19 and the like inside, and has a structure in which the primary fluid is evaporated inside. Inside the heating device 6, an insulating coating electrode 20 for applying a high piezoelectric field to the gas phase is provided, and a voltage is applied by a high voltage power supply 21. By applying a high piezoelectric field, the surface tension and viscosity of the fluid decrease, and the evaporation of the primary fluid is promoted (the Asakawa effect). Thus, intermittent or pulsating primary fluid flow is created by pulsed and periodic application of a high piezoelectric field. In FIG. 7, the high voltage power supply 21 is a DC power supply, but may be an AC power supply.

非 The unsteady flow of the primary fluid described above is controlled to be an intermittent flow or a pulsating flow of several Hz to several tens Hz.

Embodiment 5 FIG.
FIG. 8 is a schematic diagram showing an embodiment in which a refrigeration cycle is configured using the ejector of the present invention.
The ejector 1 mainly includes a nozzle 2 and a diffuser 3. The nozzle 2 is connected to a primary fluid heating device 6 and a primary fluid supply device 7 via a primary fluid supply pipe 5. The ejector 1 is connected to an evaporator 51 via a secondary fluid supply pipe 8. A condenser 52 is connected to the outlet side of the ejector 1 via an outlet pipe 10. The mixture of the primary fluid and the secondary fluid flowing into the condenser 52 is cooled and condensed by a cooling water pipe 54 connected to the condenser 52. The condensed liquid flows through the pipe 58 and is returned to the primary fluid heating device 6 by the primary fluid supply device 7, and at the same time, returns to the evaporator 51 via the secondary fluid return pipe 59 and the pressure reducing valve 57.
A temperature drop, that is, freezing occurs due to heat of vaporization (latent heat of evaporation) of the secondary fluid generated when the secondary fluid in the evaporator 51 is sucked by the ejector 1, and a cooling load 56 connected to the evaporator 51. To cool.

By using the ejector 1, the efficiency of the ejector is improved as described above, so that the flow rate ratio of the secondary fluid to the primary fluid (= [secondary fluid flow rate] / [primary fluid flow rate]) increases, and the refrigerator Efficiency (COP) is improved.

As the heat source of the heat exchanger 19 connected to the primary fluid heating device 6, in addition to power from combustion of electric power and fuel, factory exhaust heat and exhaust gas heat are used. Water, chlorofluorocarbon, alcohol, ammonia, or a mixture thereof is used as the primary and secondary fluid refrigerants.

1 is a schematic diagram of an ejector according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing a group of thin tubes in FIG. 1. It is explanatory drawing which shows the discharge phenomenon of the primary fluid in a thin tube group. FIG. 4 is an operation explanatory view showing flows of a primary fluid and a secondary fluid in the ejector of the present invention. It is a schematic diagram of an ejector according to Embodiment 2 of the present invention. It is a schematic diagram of an ejector according to Embodiment 3 of the present invention. It is a schematic diagram of an ejector according to Embodiment 4 of the present invention. It is a schematic diagram of a refrigeration system according to Embodiment 5 of the present invention. It is a schematic diagram of a conventional ejector. FIG. 4 is a cross-sectional view of the ejector shown in US Pat. No. 6,138,456.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Ejector 2 Nozzle 3 Diffuser 4 Introducing part 5 Primary fluid supply pipe 6 Primary fluid heating device 7 Primary fluid supply device 8 Secondary fluid supply pipe 9 Secondary fluid supply part 10 Outflow pipe 11 Small tube group 12 Small tube 13 Heating means 16 Primary fluid Mass 17 Secondary fluid mass 18 Primary fluid supply control device 20 Insulated coating electrode 21 High voltage power supply 51 Evaporator 52 Condenser

Claims (4)

When performing energy exchange between the high-energy fluid and the low-energy fluid by direct pressure exchange between the two fluids inside the ejector, the loss of effective energy is reduced by making the high-energy fluid an unsteady flow. How to improve ejector efficiency. When performing energy exchange between the two fluids by pressure exchange by direct contact between the high-energy fluid and the low-energy fluid inside the ejector, the high-energy fluid is set so that the interface between the two fluids is almost perpendicular to the ejector axis direction. A method for suppressing an effective energy loss of an ejector, characterized in that the flow rate of the ejector is an unsteady flow. 2. The method according to claim 1, wherein the unsteady flow is an intermittent flow or a pulsating flow. 3. The method according to claim 2, wherein the unsteady flow is an intermittent flow or a pulsating flow.

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