JP2008139019A - Ejector cycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a refrigerant to easily flow to a second evaporator by increasing the pressure rise by an ejector, and easily form different temperature zones in the first and the second evaporators 4, 7, respectively. <P>SOLUTION: Hydrocarbon isobutane, ammonia, or carbon dioxide is used as the refrigerant. The relatively conventional ejector cycle uses, as the refrigerant, hydrocarbon isobutane, ammonia, or carbon dioxide having greater expansion loss. These refrigerants have an enthalpy difference, as an input of the ejector 3, which is greater than that of a refrigerant used in the conventional refrigerator. Since the refrigerator which is greater in the input of the ejector 3 is used, it is possible to increase the pressure rise by the ejector 3, which allows the refrigerant to easily flow to the second evaporator 4. This facilitates forming different temperature zones in the first and the second evaporators 4, 7, respectively, and the more effective operaton is practicable. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, the refrigerant is decompressed and expanded to suck the vapor-phase refrigerant evaporated in the evaporator, and the expansion energy (kinetic energy discarded by the decompression means such as an expansion valve in a normal vapor compression refrigeration cycle) The present invention relates to an ejector cycle that uses an ejector that converts pressure energy to increase the suction pressure of the compressor, and in particular, a first evaporator that evaporates the refrigerant flowing out of the ejector and exhibits refrigeration capacity, and flows into the ejector. The present invention relates to an ejector cycle including a second evaporator that evaporates a refrigerant and exhibits a refrigerating capacity.

As a conventional technique, for example, as disclosed in Patent Document 1, a refrigerant circulation circuit including a compressor, a condenser, an ejector, a first evaporator downstream of the ejector, a second evaporator upstream of the ejector, and a gas-liquid separator is proposed. Has been.
JP 52-30951 A

  However, in the ejector cycle as shown in the above prior art, the pressure rise in the ejector is small and the pressure loss of the evaporator is large, so that it is difficult for the refrigerant to flow to the second evaporator and the refrigeration cycle is not established. . In addition, even when the refrigeration cycle is established, there is a problem that it is difficult to create different temperature zones because there is almost no pressure difference between the first evaporator and the second evaporator.

An object of the present invention is to provide an ejector cycle in which heat is exchanged even around the diffuser portion of the ejector.
An object of the present invention is to provide an ejector cycle in which an ejector and an evaporator are integrated to save space.
The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to increase the pressure rise in the ejector so that the refrigerant can easily flow into the second evaporator, and the first and second An object of the present invention is to provide an ejector cycle in which it is easy to create different temperature zones in the evaporator.

In order to achieve the above object, the present invention employs technical means described in claims 1 to 6. That is, in the invention described in claim 1, in the ejector cycle including an evaporator for evaporating the refrigerant flowing out from the ejector, the heat exchange fin (44) that also exchanges heat around the diffuser portion (3d) of the ejector (3). It is characterized by providing .

In the invention according to claim 2, in the ejector cycle having an evaporator for evaporating the refrigerant flowing out from the ejector, the diffuser portion (3d) of the ejector (3) is connected to the refrigerant passage (43) inside the evaporator (4). The heat exchanging fins (44) for exchanging heat are also provided around the diffuser portion (3d) .

In the invention according to claim 3, the first evaporator that evaporates the refrigerant flowing out from the ejector and exchanges heat with the heat exchange air, and evaporates the refrigerant flowing into the ejector to exchange heat with the heat exchange air. in the ejector cycle and a second evaporator which, you are characterized by providing an ejector diffuser portion (3) heat exchange fins (44) also a heat exchange air heat exchanger around (3d).

According to a fourth aspect of the present invention, there is provided a first evaporator that evaporates the refrigerant flowing out from the ejector and exerts a refrigerating capacity, and a second evaporator that evaporates the refrigerant flowing into the ejector and exerts a refrigerating capacity. in the ejector cycle having a you are characterized by providing an ejector diffuser portion (3) heat exchange fins (44) also a heat exchange air heat exchanger around (3d).

In the invention according to claim 5, the compressor (1) that sucks and compresses the refrigerant, the condenser (2) that cools and condenses the refrigerant discharged from the compressor (1), and the condenser ( 2) The pressure energy of the high-pressure refrigerant flowing out from 2) is converted into velocity energy, and the refrigerant is sucked by the high-speed refrigerant flow ejected from the nozzle (31) and the nozzle (31) that decompresses and expands the refrigerant. An ejector (3) having a boosting section (3c, 3d) for boosting the pressure of the refrigerant by mixing the injected refrigerant and the sucked refrigerant while converting the velocity energy into pressure energy, and the refrigerant flowing out of the ejector (3) A first evaporator (4) that exhibits the refrigerating capacity by evaporating the refrigerant, a second evaporator (7) that exhibits the refrigerating capacity by evaporating the refrigerant, and the evaporated gas-phase refrigerant is sucked into the ejector, 1 evaporator (4) The refrigerant flowing out of the refrigerant is separated into a gas-phase refrigerant and a liquid-phase refrigerant to store the liquid-phase refrigerant, and the liquid-phase refrigerant is supplied to the second evaporator (7) and the gas-phase refrigerant is supplied to the compressor (1). And a heat exchange fin (44) for exchanging heat with air for heat exchange is also provided around the diffuser part (3d) of the booster part (3c, 3d) of the ejector (3). it is characterized in that was.
In the invention according to claim 6, in the ejector cycle according to claim 3, 4 or 5, the diffuser portion (3d) of the ejector (3) is connected to the refrigerant passage inside the first evaporator (4). It is characterized in that it is united or integrated with (43) in heat exchange .

In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows the correspondence of the reference example mentioned later and the specific means as described in embodiment.

( Reference example )
Hereinafter, reference examples of the present invention will be described with reference to the drawings. In this reference example, the ejector cycle is applied to a refrigerator-freezer for home use, and FIG. 1 is a schematic diagram of the ejector cycle according to the reference example . Reference numeral 1 denotes a compressor that sucks and compresses a refrigerant, and an electric motor (not shown) is integrated as a drive source. The operation of the electric motor is controlled by a control device (control means) 8 described later. Reference numeral 2 denotes a condenser (condenser) that exchanges heat between the refrigerant discharged from the compressor 1 and outside air sent from a blower (not shown) to cool and condense the refrigerant.

  Reference numeral 7 denotes a second evaporator that exhibits a refrigerating capacity by exchanging heat between the air blown into the freezer and the liquid refrigerant to evaporate the liquid refrigerant. The second evaporator 7 has a second blower fan (second blower unit) 71 for passing heat exchange air, and a second temperature sensor (second blown air temperature detector unit) 72 for detecting the blown air temperature. And. The temperature detected by the second temperature sensor 72 is input to the control device 8, and the operation of the second blower fan 71 is controlled by the control device 8. In addition, 3 decompresses and expands the high-pressure refrigerant flowing out of the condenser 2 and sucks the vapor-phase refrigerant evaporated in the second evaporator 7 and converts the expansion energy into pressure energy to increase the suction pressure of the compressor 1. It is an ejector.

  Here, the ejector 3 converts the pressure energy (pressure head) of the high-pressure refrigerant flowing out of the capacitor 2 into velocity energy (speed head) to decompress and expand the refrigerant, and a high-speed refrigerant flow ejected from the nozzle 31 The gas phase refrigerant evaporated in the second evaporator 7 by (jet flow) is mixed with the suction part 3b for sucking from the low pressure inflow part 3a, and the refrigerant injected from the nozzle 31 and the refrigerant sucked from the second evaporator 7. The mixing unit 3c includes a diffuser unit 3d that converts pressure energy into pressure energy to increase the pressure of the refrigerant.

  At this time, in the mixing unit 3c, the driving flow and the suction flow are mixed so that the sum of the momentum of the driving flow and the momentum of the suction flow is preserved, so that the refrigerant pressure (static pressure) also exists in the mixing unit 3c. Rises. On the other hand, in the diffuser portion 3d, the velocity energy (dynamic pressure) of the refrigerant is converted into pressure energy (static pressure) by gradually increasing the cross-sectional area of the passage. Therefore, in the ejector 3, the mixing portion 3c and the diffuser portion 3d Both increase the refrigerant pressure. Therefore, the mixing unit 3c and the diffuser unit 3d are collectively referred to as a boosting unit.

Incidentally, in this reference example , in order to accelerate the speed of the refrigerant ejected from the nozzle 51 to the speed of sound or more, a Lahar nozzle (not shown) having a throat (not shown) whose passage area is most reduced in the middle of the passage (Fluid Engineering (University of Tokyo Press) Of course, a tapered nozzle may be adopted. In this reference example , the hole diameters of the nozzle 31 and the mixing portion 3c are selected so that the equivalent diameter ratio, which is the ratio of the equivalent diameter of the mixing portion 3c to the outlet equivalent diameter of the nozzle 31, is 1.05 or more. .

The equivalent diameter means a diameter when the cross-sectional area of the refrigerant passage is converted into a circle. In this reference example , the outlet of the nozzle 31 and the mixing portion 3c are circular, and therefore the equivalent diameter is the same as that of the nozzle 31. It becomes an exit and mixing part 3c. Incidentally, in this reference example , the equivalent diameter of the mixing portion 3c is constant up to the diffuser portion 3d, but the cross-sectional area of the mixing portion 3c may be tapered so as to increase toward the diffuser portion 3d. However, in this case, the equivalent diameter of the mixing unit 3c is defined by the inlet of the mixing unit 3c.

  The ejector 3 has a variable throttle mechanism 32 that optimally controls the throttle diameter, that is, the nozzle outlet diameter in accordance with the load fluctuation, in accordance with the refrigerant circulation flow rate. The ejector 3 has a variable nozzle capable of varying the (diaphragm diameter). The variable throttle mechanism 32 has its throttle opening controlled by the control device 8.

  Reference numeral 4 denotes a first evaporator that exhibits a refrigerating capacity by exchanging heat between the refrigerant flowing out of the ejector 3 and the air blown into the refrigerator to evaporate the refrigerant. The first evaporator 4 has a first blower fan (first blower unit) 41 for ventilating heat exchange air, and a first temperature sensor (first blown air temperature detector unit) 42 for detecting the blown air temperature. And. The temperature detected by the first temperature sensor 42 is input to the control device 8, and the operation of the first blower fan 41 is controlled by the control device 8.

  Further, reference numeral 5 in FIG. 1 denotes a gas-liquid separator in which the refrigerant flowing out from the first evaporator 4 flows in, separates the flowing-in refrigerant into a gas phase refrigerant and a liquid phase refrigerant, and stores the liquid phase refrigerant. The separated gas-phase refrigerant is sucked into the compressor 1, and the separated liquid-phase refrigerant is sucked into the second evaporator 7 side. In the refrigerant passage connecting the gas-liquid separator 5 and the second evaporator 7, the refrigerant sucked by the second evaporator 7 is decompressed to reliably reduce the pressure (evaporation pressure) in the second evaporator 7. For this purpose, a throttle valve 6 is provided. The throttle valve 6 is, for example, an electromagnetic type, so that the pressure loss of the circulating refrigerant can be varied, and the circulation can be closed as necessary. The throttle opening is controlled by the control device 8. .

  The control device 8 that controls each device described above includes functions such as a CPU, a ROM, a RAM, and an I / O port, and incorporates a microcomputer having a known structure. The sensor signals from the first and second temperature sensors 42 and 72 for detecting the temperature of the air blown from the first and second evaporators 4 and 7 are converted into A / D signals by an input circuit (A / D conversion circuit) (not shown). After being D-converted, it is configured to be input to a microcomputer.

  Next, the general operation of this ejector cycle will be described. When the compressor 1 is started, the gas-phase refrigerant is sucked into the compressor 1 from the gas-liquid separator 5, and the compressed refrigerant is discharged to the condenser 2. The refrigerant cooled by the condenser 2 is decompressed and expanded substantially isentropically (adiabatically) at the nozzle 31 of the ejector 3 and sucks the refrigerant in the second evaporator 7. Next, the refrigerant sucked from the second evaporator 7 and the refrigerant blown out from the nozzle 31 are mixed by the mixing unit 3c and converted into static pressure by the diffuser unit 3d and discharged from the ejector 3. The

  That is, the jet flow (driving flow refrigerant) flowing out from the nozzle 31 reduces its flow velocity while sucking and accelerating the refrigerant from the second evaporator 7. At this time, the flow rate of the suction gas (suction flow refrigerant) sucked from the second evaporator 7 and the flow rate of the driving flow refrigerant are substantially equal at the refrigerant outlet portion of the mixing portion 3c (refrigerant inlet portion of the diffuser portion 3d). The mixed refrigerant flows into the diffuser portion 3d and increases the pressure while decreasing the flow velocity.

  The refrigerant discharged from the ejector 3 flows into the first evaporator 4 and returns to the gas-liquid separator 5 while absorbing heat from the air blown into the refrigerator compartment and evaporating. On the other hand, since the refrigerant in the second evaporator 7 is sucked by the ejector 3, the liquid-phase refrigerant flows into the second evaporator 7 from the gas-liquid separator 5 through the throttle valve 6, and the refrigerant that has flowed into the second evaporator 7. Absorbs heat from the air blown into the freezer compartment and evaporates.

FIG. 3 is a ph diagram of an ejector cycle according to a reference example of the present invention. As apparent from the ph diagram shown in FIG. 3, in the ejector cycle, the isentropy is changed in the ejector 3 (nozzle 31), so that a normal vapor compression refrigeration in which high-pressure refrigerant is expanded by equal enthalpy (decompression) Compared to the cycle, the dryness of the refrigerant immediately after decompression is reduced. Therefore, a gas-liquid two-phase refrigerant having a low dryness (a gas-liquid two-phase refrigerant having a large amount of liquid-phase refrigerant) can be supplied to the gas-liquid separator 5.

  Further, the liquid-phase refrigerant is supplied to the second evaporator 7 by the gas-liquid separator 5, but the gas-liquid separator 5 has a gas-liquid two-phase refrigerant (a lot of liquid-phase refrigerant) with a low dryness. (Gas-liquid two-phase refrigerant) is supplied, the ratio of the gas-phase refrigerant contained in the refrigerant supplied from the gas-liquid separator 5 to the second evaporator 7 becomes extremely small, and the second evaporation from the gas-liquid separator 5 The fluctuation range of the pressure loss generated when the refrigerant is supplied to the vessel 7 is reduced. Therefore, since the pressure fluctuation in the second evaporator 7 is reduced, the change in the refrigerant temperature (evaporation temperature) in the second evaporator 7 can be reduced. As a result, the refrigerating capacity (heat absorption capacity) in the second evaporator 7 can be improved.

Next, the characteristics (effects) of this reference example will be described. First, as a refrigerant, hydrocarbon isobutane, ammonia, or carbon dioxide is used. According to this, in the same ejector cycle as before, hydrocarbon isobutane having a large expansion loss, ammonia, or carbon dioxide is used as a refrigerant. FIG. 2 is a table showing a comparison of the enthalpy differences Δie of the respective refrigerants (comparison at an ambient temperature of 25 ° C. and an internal temperature of −18 ° C.).

  As shown in the table, the refrigerant (isobutane / ammonia / carbon dioxide) has a higher enthalpy difference Δie that is input to the ejector 3 than the R134a refrigerant conventionally used in refrigerators and the like. Thus, since the refrigerant | coolant with a large input of the ejector 3 is used, the pressure rise of the ejector 3 can be enlarged and a refrigerant | coolant can flow into the 2nd evaporator 7 easily. This also makes it easy to create different temperature zones for the first and second evaporators 4 and 7, respectively, and enables more efficient operation.

FIG. 3 is a ph diagram of an ejector cycle according to a reference example of the present invention. In order to establish the ejector cycle, the pressure increase (a → b) of the ejector 3 is ΔPeje, the pressure loss (b → c) ΔPeva1 of the first evaporator, and the pressure loss (d → e) of the second evaporator is ΔPeva2. Then, it is necessary to always satisfy ΔPje> ΔPeva1 + ΔPeva2. In particular, in the first evaporator 4, since both the driving flow rate and the suction flow rate flow, the pressure loss (ΔPeva1) is large, and it has been difficult to establish a cycle conventionally.

  Therefore, the second evaporator 7 is used in the freezing area. According to this, the pressure on the low pressure side is lowered by using the second evaporator 7 not in the air-conditioning area but in the refrigeration area (PL1 → PL2 in FIG. 3). As a result, the difference between the enthalpy line corresponding to the input of the ejector 3 (thick dotted line in FIG. 3) and the enthalpy difference Δie1 when used in the air-conditioning area is larger than the enthalpy difference Δie2 when used in the refrigeration area. 3 efficiency can be improved.

  The efficiency of the ejector 3 is defined by the product of the flow rate of refrigerant flowing through the condenser (high-pressure side heat exchanger) 2 and the enthalpy difference Δie at the inlet / outlet of the nozzle 31. The sum of the refrigerant flow rate indicating how much has been recovered and the refrigerant flow rate flowing through the second evaporator (low-pressure side heat exchanger) 7 and the pressure recovery at the ejector 3 are defined.

  The second evaporator 7 is used as a refrigeration region at -18 ° C or lower, and the first evaporator 4 is used as a refrigerated region at 5 ° C or lower. According to this, the second evaporator 7 whose pressure is lowered is used for refrigeration, and the slightly higher pressure first evaporator 4 is used for refrigeration in a different temperature zone, so that it can be easily applied to, for example, a refrigerator-freezer.

In addition, a throttle valve 6 is provided between the gas-liquid separator 5 and the second evaporator 7, and the refrigeration single operation by the first evaporator 4 is performed by fully closing the throttle valve 6. In addition, the first evaporator 4 is provided with a first blower fan 41 that blows air for heat exchange to the first evaporator 4, and the freezing operation by the second evaporator 7 is performed by stopping the blowing by the first blower fan 41. According to these, it is possible to perform a freezing independent operation or a refrigerating independent operation in an ejector cycle similar to the conventional one without increasing the number of compressors to make two cycles.
( First embodiment )
FIG. 4 is a schematic cross-sectional view showing an integral structure of the ejector 3 and the first evaporator 4 in the first embodiment of the present invention. In the example of FIG. 4, the diffuser portion 3 d, which is a boosting portion of the ejector 3, is combined or integrated with the refrigerant passage 43 in the first evaporator 4 in a heat exchange manner. Incidentally, 44 is a heat exchange fin, and is also provided around the diffuser portion 3d so as to exchange heat with heat exchange air sent from the first blower fan 41. According to this, since the ejector 3 and the first evaporator 4 are integrated, space saving can be achieved.
(Other embodiments)
In the above-described embodiment, the present ejector cycle is applied to a refrigerator-freezer. However, the present invention is not limited to this, and is applied to a refrigerator, a refrigerator, a cooling device, and a combination of these. Also good. The hydrocarbon is not limited to isobutane but may be propane.

It is a schematic diagram of the ejector cycle which concerns on the reference example of this invention. It is a table | surface which shows the comparison of the enthalpy difference (DELTA) ie of each refrigerant | coolant. It is a ph diagram of an ejector cycle concerning a reference example of the present invention. It is a cross-sectional schematic diagram which shows the integral structure of the ejector 3 and the 1st evaporator 4 in 1st Embodiment of this invention.

Explanation of symbols

1 ... Compressor 2 ... Condenser
3 ... Ejector 3c ... Mixing unit (pressure booster)
3d ... Diffuser section (boost section)
DESCRIPTION OF SYMBOLS 4 ... 1st evaporator 5 ... Gas-liquid separator 6 ... Throttle valve 7 ... 2nd evaporator 31 ... Nozzle 41 ... 1st ventilation fan (1st ventilation means)

Claims (6)

A compressor (1) for sucking and compressing refrigerant;
A condenser (2) for cooling and condensing the refrigerant discharged from the compressor (1);
A second evaporator (7) that evaporates the refrigerant and exerts a refrigerating capacity;
A nozzle (31) for converting the pressure energy of the high-pressure refrigerant flowing out of the condenser (2) into velocity energy to decompress and expand the refrigerant, and the second evaporator by a high-speed refrigerant flow injected from the nozzle (31). The vapor phase refrigerant evaporated in (7) is sucked, and the velocity energy is changed to pressure energy while mixing the refrigerant injected from the nozzle (31) and the vapor phase refrigerant sucked from the second evaporator (7). An ejector (3) having a boosting section (3c, 3d) for converting and boosting the pressure of the refrigerant;
A first evaporator (4) that evaporates the refrigerant flowing out of the ejector (3) and exhibits refrigeration capacity;
Separating the refrigerant flowing out from the first evaporator (4) into a gas-phase refrigerant and a liquid-phase refrigerant and storing the liquid-phase refrigerant, and supplying the liquid-phase refrigerant to the second evaporator (7), A gas-liquid separator (5) for supplying the gas-phase refrigerant to the compressor (1),
An ejector cycle characterized in that hydrocarbon isobutane, ammonia, or carbon dioxide is used as the refrigerant. A compressor (1) for sucking and compressing refrigerant;
A condenser (2) for cooling and condensing the refrigerant discharged from the compressor (1);
A second evaporator (7) that evaporates the refrigerant and exerts a refrigerating capacity;
A nozzle (31) for converting the pressure energy of the high-pressure refrigerant flowing out of the condenser (2) into velocity energy to decompress and expand the refrigerant, and the second evaporator by a high-speed refrigerant flow injected from the nozzle (31). The vapor phase refrigerant evaporated in (7) is sucked, and the velocity energy is changed to pressure energy while mixing the refrigerant injected from the nozzle (31) and the vapor phase refrigerant sucked from the second evaporator (7). An ejector (3) having a boosting section (3c, 3d) for converting and boosting the pressure of the refrigerant;
A first evaporator (4) that evaporates the refrigerant flowing out of the ejector (3) and exhibits refrigeration capacity;
Separating the refrigerant flowing out from the first evaporator (4) into a gas-phase refrigerant and a liquid-phase refrigerant and storing the liquid-phase refrigerant, and supplying the liquid-phase refrigerant to the second evaporator (7), A gas-liquid separator (5) for supplying the gas-phase refrigerant to the compressor (1),
An ejector cycle, wherein the second evaporator (7) is used in a refrigeration region.   The ejector according to claim 2, wherein the second evaporator (7) is used as a refrigeration zone at -18 ° C or lower and the first evaporator (4) is used as a refrigeration zone at 5 ° C or lower. cycle.   The said pressure | voltage rise part (3c, 3d) and the said 1st evaporator (4) of the said ejector (3) were united | combined by heat exchange, or were integrated, The Claim 1 or Claim 2 characterized by the above-mentioned. Ejector cycle.   A throttle valve (6) is provided between the gas-liquid separator (5) and the second evaporator (7), and the first evaporator (4) is fully closed by closing the throttle valve (6). The ejector cycle according to claim 1 or 2, wherein the refrigeration single operation is performed.   The second evaporator (7) is provided with first air blowing means (41) for blowing heat exchange air to the first evaporator (4) and stopping air blowing by the first air blowing means (41). The ejector cycle according to claim 1 or 2, wherein the refrigeration single operation is performed.

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