JP2003262413A - Ejector cycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cause a sufficient amount of refrigerant to flow in an evaporator in an ejector cycle. <P>SOLUTION: The pressure loss of a refrigerant passage through which suction flow flows is set to be as small as possible so that, when the flow rate of refrigerant in the evaporator 30 is equal to a predetermined flow rate, the total pressure loss Δpall of the suction flow is less than an increase Δpej of pressure in an ejector 40. More specifically, 1) a restrictor 60 is installed in a position that is as close to the evaporator 30 as possible in the flow of refrigerant; 2) the ejector 40 is integrated with a gas-liquid separator 50; 3) the gas-liquid separator 50 is integrated with the evaporator 30; 4) the ejector 40, the gas-liquid separator 50, and the evaporator 30 are integrated together; and 5) the diameter of the refrigerant piping is made as large as possible. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor compression refrigeration cycle for transferring heat on a low temperature side to a high temperature side, converting expansion energy into pressure energy while decompressing and expanding a refrigerant to reduce suction pressure of a compressor. The present invention relates to an ejector cycle having an ejector for raising.

[0002]

As is well known, the ejector cycle is a well-known ejector cycle in which a refrigerant is decompressed and expanded by an ejector to suck a vapor phase refrigerant evaporated in an evaporator and expansion energy is converted into pressure energy. It is a refrigerating cycle in which the suction pressure of the compressor is increased by converting into.

By the way, in a refrigerating cycle (hereinafter referred to as an expansion valve cycle) in which a refrigerant is isenthalpically decompressed by a decompression means such as an expansion valve, the refrigerant flowing out of the expansion valve flows into an evaporator. In the ejector cycle,
The refrigerant flowing out of the ejector flows into the gas-liquid separator, the liquid-phase refrigerant separated by the gas-liquid separator is supplied to the evaporator, and the gas-phase refrigerant separated by the gas-liquid separator is sucked into the compressor. To be done.

That is, in the expansion valve cycle, the refrigerant circulates in the order of compressor → radiator → expansion valve → evaporator → compressor 1.
On the other hand, in the ejector cycle, as shown in FIG. 1, the refrigerant flow circulates in the order of compressor 10 → radiator 20 → ejector 40 → gas-liquid separator 50 → compressor 10 (hereinafter, This flow is referred to as a drive flow), and a refrigerant flow that circulates in the order of gas-liquid separator 50 → evaporator 30 → ejector 40 → gas-liquid separator 50 (hereinafter, this flow is referred to as a suction flow) exists. To do.

At this time, the drive flow is circulated by the compressor 10, whereas the suction flow 10 is the pressure increase amount generated in the ejector 40, that is, the pressure difference between the refrigerant outlet of the ejector 40 and the vapor-phase refrigerant inlet. Since it is circulated as a pump drive source, the pressure loss generated in the refrigerant passage from the refrigerant outlet of the ejector 40 to the gas-phase refrigerant inlet of the ejector 40 via the gas-liquid separator 50 and the evaporator 30 is equal to the amount of pressure increase in the ejector 40. If it is larger than this, the suction flow cannot circulate, the ejector cycle is not established, or the flow rate of the suction flow becomes small, and the evaporator 30 cannot exhibit sufficient refrigerating capacity (heat absorbing capacity).

In view of the above points, an object of the present invention is to prevent the occurrence of problems such as the ejector cycle not being established or the evaporator 30 not being able to exert a sufficient refrigerating capacity. To do.

[0007]

In order to achieve the above-mentioned object, the present invention provides a compressor (10) for sucking and compressing a refrigerant and a compressor (10) for discharging the refrigerant. The radiator (20) for cooling the refrigerant, the evaporator (30) for evaporating the refrigerant and absorbing heat, and the pressure energy of the high-pressure refrigerant flowing out from the radiator (20) are converted into velocity energy to expand the refrigerant under reduced pressure. Nozzle (41), nozzle (4
1) The high velocity refrigerant flow injected from the evaporator (3
0) sucks the vapor phase refrigerant and mixes the refrigerant injected from the nozzle (41) with the refrigerant sucked from the evaporator (30) to convert velocity energy into pressure energy to increase the pressure of the refrigerant. An ejector (40) having a pressurizing section (42, 43) for causing the refrigerant to be separated into a gas-phase refrigerant and a liquid-phase refrigerant and supplying the liquid-phase refrigerant to the evaporator (30) to compress the gas-phase refrigerant. A gas-liquid separator (50) supplied to (10), and a gas-liquid separator (50) from the refrigerant outlet of the ejector (40) when the flow rate of the refrigerant flowing in the evaporator (30) becomes a predetermined flow rate. And the pressure loss (Δpall) generated in the refrigerant passage from the evaporator (30) to the vapor-phase refrigerant suction port (40a) of the ejector (40) is less than the pressure increase amount (Δpej) at the ejector (40). Is set to To.

As a result, it is possible to prevent the occurrence of a problem such that the ejector cycle is not established or the evaporator (30) cannot exhibit a sufficient refrigerating capacity.

According to the second aspect of the invention, the throttle means (60) provided in the refrigerant passage connecting the gas-liquid separator (50) and the evaporator (30) has the evaporator (3) in the refrigerant flow.
0) It is characterized by being installed in the vicinity.

As a result, the total pressure loss of the suction flow can be reduced, so that the above problems can be reliably prevented.

The invention according to claim 3 is characterized in that the ejector (40) and the gas-liquid separator (50) are integrated.

As a result, the total pressure loss of the suction flow can be reduced, so that the above problems can be reliably prevented.

The invention according to claim 4 is characterized in that the gas-liquid separator (50) and the evaporator (30) are integrated.

As a result, the total pressure loss of the suction flow can be reduced, so that the above problems can be reliably prevented.

The invention as set forth in claim 5 is characterized in that the ejector (40), the gas-liquid separator (50) and the evaporator (30) are integrated.

As a result, the total pressure loss of the suction flow can be reduced, so that the above problems can be reliably prevented.

Incidentally, the reference numerals in the parentheses of the above-mentioned means are examples showing the correspondence with the concrete means described in the embodiments described later.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In this embodiment, an ejector cycle according to the present invention is applied to an air conditioning system for a vehicle, FIG. 1 is a schematic view of the ejector cycle, and FIG. 2 is a mounting state on a vehicle. It is a schematic diagram which shows. Since FIG. 2 is a schematic diagram, the features of this embodiment are not completely illustrated.

In FIG. 1, a compressor 10 is a well-known variable capacity type compressor that receives power from a running engine to suck and compress a refrigerant, and a radiator 20 discharges the refrigerant and outdoor air from the compressor 10. Is a high-pressure side heat exchanger for exchanging heat to cool the refrigerant.

By the way, in this embodiment, since Freon is used as the refrigerant, the refrigerant pressure in the radiator 20 is below the critical pressure of the refrigerant, and the refrigerant is condensed in the radiator 20.

The evaporator 30 is a low-pressure side heat exchanger that cools the air blown into the room by evaporating the refrigerant by evaporating the liquid phase refrigerant by exchanging heat between the air blowing into the room and the liquid phase refrigerant. The ejector 40 expands the refrigerant under reduced pressure to suck the vapor-phase refrigerant evaporated in the evaporator 30, and converts the expansion energy into pressure energy to increase the suction pressure of the compressor 10.

As shown in FIG. 3, the ejector 40 converts the pressure energy of the inflowing high-pressure refrigerant into velocity energy and expands the refrigerant under reduced pressure by a nozzle 41 and a high-velocity refrigerant flow ejected from the nozzle 41 to evaporate the same. A mixing section 42 for mixing the vapor phase refrigerant evaporated in the vessel 30 with the refrigerant flow ejected from the nozzle 41, and the nozzle 41
The diffuser 43 or the like is configured to convert the velocity energy into pressure energy while increasing the pressure of the refrigerant while mixing the refrigerant injected from the and the refrigerant sucked from the evaporator 30.

Incidentally, in the present embodiment, in order to accelerate the velocity of the refrigerant ejected from the nozzle 41 to a speed higher than the sonic velocity, a Laval nozzle having a throat portion with the smallest passage area in the middle of the passage (Fluid Engineering (The University of Tokyo Press) (See) is adopted.

In the mixing section 42, the nozzle 41
Since the sum of the momentum of the refrigerant flow injected from the and the momentum of the refrigerant flow sucked from the evaporator 30 to the ejector 40 is stored, the static pressure of the refrigerant also rises in the mixing section 42. On the other hand, in the diffuser 43, the dynamic pressure of the refrigerant is converted into the static pressure by gradually increasing the passage cross-sectional area, so in the ejector 40, the refrigerant pressure is increased by both the mixing section 42 and the diffuser 43. . Therefore, the mixing section 42 and the diffuser 43 are generically called a boosting section.

In FIG. 1, the gas-liquid separator 50 receives the refrigerant flowing out of the ejector 40 and separates the inflowing refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant to store the refrigerant. The gas-phase refrigerant outlet of the gas-liquid separator 50 is connected to the suction side of the compressor 10, and the liquid-phase refrigerant outlet is connected to the inflow side of the evaporator 30.

The throttle 60 is a throttle means provided in a refrigerant passage connecting the gas-liquid separator 50 and the evaporator 30 to reduce the refrigerant flowing into the evaporator 30 to the evaporation pressure. In the present embodiment, the throttle 60 is used. It uses a fixed throttle with a fixed opening.

FIG. 4 is a ph diagram showing the macro operation of the ejector cycle as a whole. Since the macro operation is the same as that of a known ejector cycle, in this embodiment, the ejector cycle as a whole is operated. The description of the macro operation is omitted. By the way, the symbol shown by ● in FIG.
It shows the state of the refrigerant at the symbol position shown by ● shown in FIG.

Next, the features of this embodiment will be described.

The total pressure loss Δpall of the suction flow (see “Prior Art and Problems to be Solved by the Invention”) is determined by the following equation, and its characteristic is as shown by the solid line in FIG. That is, it increases quadratically with an increase in the flow rate of the refrigerant flowing through the evaporator 30.

[0030]

[Equation 1] Δpall = Δpe + Δpeej + Δpeja + Δpa + Δpav
+ Δpv + Δpve where Δpe represents the pressure loss in the evaporator 30,
peej is the pressure loss in the refrigerant passage connecting the vapor-phase refrigerant inlet 40a of the ejector 40 (see FIG. 3) and the refrigerant outlet of the evaporator 30, and Δpeja is the refrigerant outlet 40b of the ejector 40 (see FIG. 3). Shows the pressure loss in the refrigerant passage connecting the gas-liquid separator 50, Δpa shows the pressure loss in the gas-liquid separator 50, and Δpav shows the pressure loss in the refrigerant passage connecting the gas-liquid separator 50 and the throttle 60. , Δpv represents the pressure loss in the throttle 60, and Δpve represents the pressure loss in the refrigerant passage connecting the throttle 60 and the refrigerant inlet of the evaporator 30.

On the other hand, the boost amount Δpe in the ejector 40
As shown by the alternate long and short dash line in FIG. 5, j decreases linearly as the flow rate of the refrigerant flowing in the evaporator 30 increases,
The flow rate of the refrigerant flowing in the evaporator 30 is the intersection of the graph showing the pressurizing characteristic of the ejector 40 (dashed line) and the graph showing the total pressure loss characteristic of the suction flow (solid line).

The graph showing the boosting characteristic of the ejector 40 varies depending on the rotation speed of the compressor 10, that is, the flow rate of the driving flow, the heat radiation capacity of the radiator 20, and the like. The tendency of “decreasing linearly with the increase of” does not change.

For this reason, the characteristic of the total pressure loss Δpall of the suction flow changes from the solid line state to the wavy line state, that is, the total pressure loss of the suction flow when the flow rate of the refrigerant flowing in the evaporator 30 becomes a predetermined flow rate. As Δpall increases, evaporator 3
Since the amount of the refrigerant flowing in 0 decreases, the evaporator 30 cannot exhibit a sufficient refrigerating capacity (heat absorbing capacity).

Therefore, in this embodiment, the total pressure loss Δpall of the suction flow when the flow rate of the refrigerant flowing in the evaporator 30 is a predetermined flow rate is the pressure increase amount Δpe in the ejector 40.
The pressure loss in the refrigerant passage through which the suction flow flows is set to be as small as possible so as to be less than j. Specifically, there are the following five means.

By installing the throttle 60 in the refrigerant flow as close to the evaporator 30 as possible, the refrigerant passage length is shortened and the pressure loss Δpve is reduced.

By integrating the ejector 40 and the gas-liquid separator 50, the refrigerant passage length is shortened and the pressure loss Δpeja is reduced.

By integrating the gas-liquid separator 50 and the evaporator 30, the length of the refrigerant passage is shortened to reduce the pressure loss Δpa.
Reduce v, Δpv and Δpve.

By integrating the ejector 40, the gas-liquid separator 50 and the evaporator 30, the refrigerant passage length is shortened and the total pressure loss Δpall is reduced.

By increasing the diameter of the refrigerant pipe as much as possible, the length of the refrigerant passage is shortened and the total pressure loss Δpa.
Make ll smaller.

(Other Embodiments) Although chlorofluorocarbon was used as the refrigerant in the above embodiments, carbon dioxide may be used as the refrigerant. When carbon dioxide is used as the refrigerant, the refrigerant pressure in the radiator 20 becomes equal to or higher than the critical pressure of the refrigerant, and the refrigerant does not condense in the radiator 20 and the refrigerant inlet side is changed to the refrigerant outlet side. There may be a temperature distribution in which the temperature of the refrigerant decreases as it goes.

The means for reducing the total pressure loss Δpall is not limited to the means shown in the above-mentioned embodiment, and any means can be used.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an ejector cycle according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing how an ejector cycle according to an embodiment of the present invention is mounted on a vehicle.

FIG. 3 is a schematic diagram of an eject according to an embodiment of the present invention.

FIG. 4 is a p-h diagram.

FIG. 5 is a characteristic diagram showing a relationship between refrigerant flow rate and pressure.

[Explanation of symbols]

10 ... Compressor, 20 ... Radiator, 30 ... Evaporator, 40 ... Ejector, 50 ... Gas-liquid separator, 60 ... Throttle.

Claims (5)

[Claims] 1. A compressor (10) for sucking and compressing a refrigerant, a radiator (20) for cooling the refrigerant discharged from the compressor (10), and an evaporator (30) for evaporating the refrigerant to absorb heat. A nozzle (41) for converting pressure energy of the high-pressure refrigerant flowing out from the radiator (20) into velocity energy to expand the refrigerant under reduced pressure; and a high-velocity refrigerant flow injected from the nozzle (41) to cause the evaporator ( 30) sucking the vapor-phase refrigerant, mixing the refrigerant injected from the nozzle (41) with the refrigerant sucked from the evaporator (30), and converting the velocity energy into the pressure energy to reduce the pressure of the refrigerant. And an ejector (40) having a booster section (42, 43) for boosting the pressure of the refrigerant, and separating the refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant, and supplying the liquid-phase refrigerant to the evaporator (30). To A gas-liquid separator (50) for supplying to the compressor (10), and when the flow rate of the refrigerant flowing in the evaporator (30) reaches a predetermined flow rate, the gas is discharged from the refrigerant outlet of the ejector (40). The gas-phase refrigerant suction port (40a) of the ejector (40) is passed through the liquid separator (50) and the evaporator (30).
The ejector cycle is characterized in that the pressure loss (Δpall) generated in the refrigerant passage up to is less than the pressure increase amount (Δpej) in the ejector (40). 2. A throttle means (6) provided in a refrigerant passage connecting the gas-liquid separator (50) and the evaporator (30).
The ejector cycle according to claim 1, wherein 0) is installed in the vicinity of the evaporator (30) in the refrigerant flow. 3. The ejector cycle according to claim 1, wherein the ejector (40) and the gas-liquid separator (50) are integrated. 4. The ejector cycle according to claim 1, wherein the gas-liquid separator (50) and the evaporator (30) are integrated. 5. The ejector cycle according to claim 1, wherein the ejector (40), the gas-liquid separator (50) and the evaporator (30) are integrated.