JP2009063182A - Vapor compression cycle using ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor compression cycle using an ejector capable of improving the lowering of a cooling performance and an amenity caused by a change in a ratio of refrigerant weight-flow rate. <P>SOLUTION: This vapor compression cycle using the ejector is provided with: a compressor 11; a heat exchanger 12; the ejector 14 having a restriction portion 14a, a refrigerant suction port 14b, a mixing portion 14c, and a booster portion 14d; a first evaporator 15 for exhausting the refrigerant to the side of the compressor 11; a second evaporator 18 connected to the refrigerant suction port 14b; and a restriction mechanism 17 for reducing the pressure of the refrigerant flowing in the second evaporator 18, wherein the restriction mechanism 17 is formed into a same constitution to the restriction portion 14a of the ejector 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vapor compression cycle using an ejector having a role of refrigerant decompression means and a refrigerant circulation means, and a plurality of evaporators. For example, the present invention relates to a vehicle air conditioner or a vehicle-mounted luggage. It is effective when applied to a vehicle refrigeration system that freezes and refrigerates.

  2. Description of the Related Art Conventionally, as described in, for example, Patent Document 1, a vapor compression cycle using an ejector (hereinafter simply referred to as a “vapor compression cycle”) having an ejector serving as a refrigerant decompression unit and a refrigerant circulation unit is known. It has been.

  The vapor compression cycle described in Patent Document 1 includes a first evaporator disposed on the outlet side (downstream side) of the ejector and a second evaporator disposed on the upstream side of the refrigerant suction port of the ejector. .

  The ejector has a well-known configuration, and mixes a nozzle portion that decompresses and expands the refrigerant, a high-speed refrigerant flow from the nozzle portion, and a suction refrigerant (refrigerant that has circulated through the second evaporator) from the refrigerant suction port. And a diffuser section as a boosting section.

Further, on the upstream side of the second evaporator, a pressure reducing means for the refrigerant flowing into the second evaporator, specifically, a fixed throttle mechanism including a capillary tube and an orifice is disposed.
JP 2007-57222 A

  In such a vapor compression cycle, normally, the predetermined flow rate is previously adjusted so that the weight flow ratio of the amount of refrigerant flowing into the second evaporator with respect to the first evaporator becomes a predetermined rate (for example, 30 to 80%). An aperture mechanism is adopted.

  In the vapor compression cycle, a structure (capillary tube or orifice) different from the throttle mechanism (nozzle) in the ejector is used as the throttle mechanism for the second evaporator.

  For this reason, when the dryness of the refrigerant changes according to the cooling heat load, the flow rate characteristics differ between the nozzle and the capillary tube (or orifice, etc.), so that the weight flow rate changes according to the respective throttle mechanism, There was a problem that the refrigerant weight flow ratio flowing into the two evaporators did not reach a predetermined ratio.

  That is, in the second evaporator, a desired refrigerant weight flow rate ratio cannot be obtained, and as a result, the cooling performance decreases due to the conditioned air that has passed through the second evaporator, and the comfort performance decreases as the width of the temperature distribution increases. There was a risk of inviting.

  In view of the above problems, an object of the present invention is to provide a vapor compression cycle using an ejector that can improve the decrease in cooling performance and comfort performance due to a change in the refrigerant weight flow ratio.

  In order to achieve the above object, the present invention employs the following technical means.

  In the first aspect of the present invention, the compressor (11) that sucks and compresses the refrigerant, the heat exchanger (12) that cools the refrigerant discharged from the compressor (11), and the heat exchanger (12) are provided. A throttle part (14a) that decompresses and expands the refrigerant on the downstream side, a refrigerant suction port (14b) into which the refrigerant is sucked in by a high-speed refrigerant flow injected from the throttle part (14a), a high-speed refrigerant flow and refrigerant suction Ejector (14) having a mixing section (14c) that mixes the suction refrigerant from the port (14b) and a boosting section (14d) that converts the velocity energy of the refrigerant flow mixed in the mixing section (14c) into pressure energy. The first evaporator (15) connected to the downstream side of the ejector (14) and discharging the refrigerant to the compressor (11) side, and branched from the upstream side of the ejector (14) to be the refrigerant suction port (14b) In the refrigerant branch passage (16) leading to The second evaporator (18) connected to the refrigerant suction port (14b) and the refrigerant branch passage (16) on the upstream side of the second evaporator (18). In the vapor compression cycle using the ejector provided with the throttle mechanism (17) for depressurizing the refrigerant flowing into (18), the throttle mechanism (17) has the same configuration as the throttle part (14a) of the ejector (14). It is characterized by being.

  According to this configuration, since the throttle mechanism (17) of the second evaporator (18) employs the same structure as the throttle part (14a) of the ejector (14), the first evaporator (15) is always used. The refrigerant weight flow ratio of the second evaporator (18) with respect to the refrigerant is kept at 50% (refrigerant inflow rate to the first evaporator (15): refrigerant inflow amount to the second evaporator (18) = 2: 1). It is.

  Even if the dryness of the refrigerant changes, since the same throttle mechanism is used, the change in the refrigerant weight flow rate ratio is caused by the throttle part (14a) in the ejector (14) and the throttle mechanism (17 for the second evaporator). ), The refrigerant weight flow rate ratio is always constant.

  Therefore, according to the vapor compression cycle using the ejector of this configuration, it is possible to improve the decrease in cooling performance and comfort performance due to the change in the refrigerant weight flow ratio.

  Note that “same” in the claims means that the structure is the same and the scale is the same.

  The invention according to claim 2 is characterized in that the throttle part (14a) and the throttle mechanism (17) are constituted by nozzles.

  According to this structure, this invention can be implemented suitably by employ | adopting a nozzle as an aperture | diaphragm | squeeze part (14a) and an aperture mechanism (17).

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description later mentioned.

(First embodiment)
FIG. 1 is a schematic diagram showing a vapor compression cycle 10 (hereinafter, simply referred to as “vapor compression cycle 10”) using an ejector according to the first embodiment of the present invention, and is applied to a refrigeration cycle apparatus for a vehicle. An example is shown. In the present embodiment, a refrigerant whose high pressure does not exceed a critical pressure, such as a refrigerant of a fluorocarbon type or a hydrocarbon type, is used as the refrigerant.

  In the vapor compression cycle 10 of the present embodiment, a compressor 11 that sucks and compresses refrigerant is rotationally driven by a vehicle travel engine (not shown) via an electromagnetic clutch 11a, a belt (not shown), and the like.

  As the compressor 11, a variable capacity compressor that can adjust the refrigerant discharge capacity by changing the discharge capacity, or a fixed capacity type that adjusts the refrigerant discharge capacity by changing the operating rate of the compressor operation by intermittently connecting the electromagnetic clutch 11a. Any of the compressors may be used. Further, if an electric compressor is used as the compressor 11, the refrigerant discharge capacity can be adjusted by adjusting the rotation speed of the electric motor.

  A condenser 12 (heat exchanger) is disposed on the refrigerant discharge side of the compressor 11. The condenser 12 cools the high-pressure refrigerant by exchanging heat between the high-pressure refrigerant discharged from the compressor 11 and the outside air (air outside the passenger compartment) blown by a cooling fan (not shown).

  A liquid receiver 12 a is provided on the outlet side of the condenser 12. As is well known, the liquid receiver 12a has a vertically long tank shape, and constitutes a gas-liquid separator that separates the gas-liquid refrigerant and accumulates excess liquid refrigerant in the cycle. The liquid receiver 12a derives the liquid refrigerant from the lower side inside the tank shape. In addition, the liquid receiver 12a is provided integrally with the condenser 12 in this example.

  A temperature type expansion valve 13 is disposed on the outlet side of the liquid receiver 12a. The temperature type expansion valve 13 is a pressure reducing means for reducing the pressure of the liquid refrigerant from the liquid receiver 12 a and has a temperature sensing part (not shown) disposed in the suction side passage of the compressor 11.

  As is well known, the temperature type expansion valve 13 detects the degree of superheat of the compressor suction side refrigerant based on the temperature and pressure of the suction side refrigerant (evaporator outlet side refrigerant described later) of the compressor 11 and sucks the compressor. The valve opening (refrigerant flow rate) is adjusted so that the degree of superheat of the side refrigerant becomes a predetermined value set in advance.

  An ejector 14 is disposed on the outlet side of the temperature type expansion valve 13. The ejector 14 is a decompression means for decompressing the refrigerant, and is also a refrigerant circulation means (momentum transporting pump) that circulates the refrigerant by a suction action (winding action) of the refrigerant flow ejected at high speed.

  In the ejector 14, the passage area of the refrigerant (intermediate pressure refrigerant) after passing through the temperature type expansion valve 13 is narrowed down so that the refrigerant is further decompressed and expanded in the same space as the refrigerant outlet of the nozzle part 14 a. The refrigerant | coolant suction port 14b which is arrange | positioned and attracts | sucks the gaseous-phase refrigerant | coolant from the 2nd evaporator 18 mentioned later is provided.

  Furthermore, a mixing portion 14c that mixes the high-speed refrigerant flow from the nozzle portion 14a and the suction refrigerant of the refrigerant suction port 14b is provided in the refrigerant flow downstream portion of the nozzle portion 14a and the refrigerant suction port 14b. And the diffuser part 14d which makes a pressure | voltage rise part is arrange | positioned in the refrigerant | coolant flow downstream of the mixing part 14c. The diffuser portion 14d is formed in a shape that gradually increases the passage area of the refrigerant, and serves to increase the refrigerant pressure by decelerating the refrigerant flow, that is, to convert the velocity energy of the refrigerant into pressure energy.

  The first evaporator 15 is connected to the outlet side of the diffuser portion 14 d of the ejector 14, and the outlet side of the first evaporator 15 is connected to the suction side of the compressor 11.

  On the other hand, the refrigerant branch flow path 16 is branched from the inlet side of the ejector 14 (intermediate portion between the outlet side of the temperature type expansion valve 13 and the inlet side of the ejector 14 = branch point Z). The downstream side is connected to the refrigerant suction port 14 b of the ejector 14.

  A throttle mechanism 17 is disposed in the refrigerant branch flow path 16, and a second evaporator 18 is disposed on the downstream side of the refrigerant flow from the throttle mechanism 17. The diaphragm mechanism 17 has the same size and structure as the nozzle portion 14 a in the ejector 14.

  Further, the vapor compression cycle 10 includes an electric blower 19 disposed on the upstream side of the evaporator 15, and air is blown by the electric blower 19 in the direction of the arrow (from top to bottom in FIG. 1). Is cooled by two evaporators 15 and 18.

  The cold air cooled by the two evaporators 15 and 18 is sent to a common cooling target space (not shown), whereby the two cooling units 15 and 18 cool the common cooling target space. Here, of the two evaporators 15 and 18, the first evaporator 15 connected to the main flow path on the downstream side of the ejector 14 is disposed on the upstream side (windward side) of the air flow, and the refrigerant suction port 14 b of the ejector 14. The second evaporator 18 connected to is disposed on the downstream side (downstream side) of the air flow.

  In the present embodiment, since the vapor compression cycle 10 is applied to a refrigeration cycle apparatus for vehicle air conditioning, the vehicle interior space becomes the cooling target space. In addition, when the vapor compression cycle 10 of the present embodiment is applied to a refrigeration cycle apparatus for a refrigeration vehicle, the space inside the refrigeration refrigerator of the refrigeration vehicle is a space to be cooled.

  Next, the operation of the vapor compression cycle 10 having the above configuration will be described. When the compressor 11 is driven by the vehicle engine, the high-temperature and high-pressure refrigerant compressed and discharged by the compressor 11 flows into the condenser 12. In the condenser 12, the high-temperature refrigerant is cooled by the outside air and condensed. The high-pressure refrigerant that has flowed out of the condenser 12 flows into the liquid receiver 12a, and the gas-liquid refrigerant is separated in the liquid receiver 12a, and the liquid refrigerant is led out from the liquid receiver 12a so as to pass through the temperature expansion valve 13. pass.

  In the temperature type expansion valve 13, the valve opening degree (refrigerant flow rate) is adjusted so that the degree of superheat of the outlet refrigerant (compressor suction refrigerant) of the first evaporator 15 becomes a predetermined value, and the high-pressure refrigerant is decompressed. The refrigerant flow after passing through the temperature type expansion valve 13 is divided into a refrigerant flow toward the ejector 14 and a refrigerant flow toward the throttle mechanism 17 from the refrigerant branch flow path 16. Here, in this embodiment, since the nozzle part 14a of the ejector 14 and the throttle mechanism 17 are completely the same structure, the flow path resistance is the same, and the refrigerant is equally divided.

  And the refrigerant | coolant flow which flowed into the ejector 14 is decompressed and expanded by the nozzle part 14a. Therefore, the pressure energy of the refrigerant is converted into velocity energy at the nozzle portion 14a, and the refrigerant is ejected at a high velocity from the outlet of the nozzle portion 14a. Due to the refrigerant pressure drop at this time, the refrigerant (gas phase refrigerant) after passing through the second evaporator 18 of the refrigerant branch flow path 16 is drawn from the refrigerant suction port 14b.

  The refrigerant ejected from the nozzle portion 14a and the refrigerant sucked into the refrigerant suction port 14b are mixed in the mixing portion 14c on the downstream side of the nozzle portion 14a and flow into the diffuser portion 14d. In the diffuser portion 14d, the passage area is enlarged, so that the speed (expansion) energy of the refrigerant is converted into pressure energy, so that the pressure of the refrigerant rises.

  Then, the refrigerant flowing out from the diffuser portion 14 d of the ejector 14 flows into the first evaporator 15. In the first evaporator 15, the low-temperature low-pressure refrigerant absorbs heat from the air blown by the electric blower 19 and evaporates. The vapor phase refrigerant after evaporation is sucked into the compressor 11 and compressed again.

  On the other hand, the refrigerant flow flowing into the refrigerant branch flow path 16 is decompressed by the throttle mechanism 17 to become a low-pressure refrigerant, and this low-pressure refrigerant flows into the second evaporator 18. In the second evaporator 18, the low-temperature low-pressure refrigerant absorbs heat from the blown air after passing through the first evaporator 15 and evaporates. The vapor phase refrigerant after evaporation is sucked into the ejector 14 through the refrigerant suction port 14b.

  According to the vapor compression cycle 10 configured as described above, the refrigerant on the downstream side of the diffuser portion 14 d of the ejector 14 is supplied to the first evaporator 15, and the refrigerant on the refrigerant branch flow path 16 side is supplied through the throttle mechanism 17. Since it can also be supplied to the two evaporators 18, the first and second evaporators 15 and 18 can simultaneously exhibit a cooling action. Therefore, the cooling air cooled by both the first and second evaporators 15 and 18 can be blown out to the cooling target space to cool (cool) the cooling target space.

  Here, FIG. 2 is a diagram for explaining the relationship between the dryness of the refrigerant and the weight flow rate in the throttle structure, in which the solid line indicates the relationship in the nozzle, and the broken line indicates the relationship in the capillary tube. As shown in FIG. 2, since the structures of the nozzle and the capillary tube are different, the graphs showing the relationship between the dryness of the refrigerant and the weight flow rate are different.

  For example, if the structure of the throttle mechanism 17 is a capillary tube and is different from the structure of the throttle mechanism (nozzle part 14 a) in the ejector 14, the flow rate ratio of the refrigerant flowing into the second evaporator 18 side with respect to the first evaporator 15. Even if (refrigerant weight flow ratio) is set in advance by the structure of the throttle mechanism 17 so as to be a predetermined ratio, if the dryness of the refrigerant changes according to the cooling heat load, the flow characteristics between the nozzle and the capillary tube May not reach a predetermined ratio due to differences.

  That is, a desired refrigerant flow ratio cannot be obtained in the second evaporator 18, and as a result, the cooling performance decreases due to the conditioned air that has passed through the second evaporator 18, and the comfort performance associated with the increase in the temperature distribution width. There is a risk of lowering.

  In this regard, in the present embodiment, since the same nozzle as the throttle mechanism (nozzle portion 14a) of the ejector 14 is employed in the throttle mechanism 17 as the pressure reducing means of the second evaporator 18, the second evaporator is always used. The refrigerant flow ratio of 18 is maintained at 50 percent (the amount of refrigerant flowing into the first evaporator 15: the amount of refrigerant flowing into the second evaporator = 2: 1). Even if the dryness of the refrigerant changes, the same structure nozzle is used, so the change in the refrigerant flow ratio is caused by the nozzle portion 14a in the ejector 14 and the nozzle for the second evaporator 18 (throttle mechanism 17). In the same manner, the refrigerant flow rate ratio is always constant.

  Therefore, in the vapor compression cycle 10 of the present embodiment, the cooling performance and the temperature distribution performance of the conditioned air can be kept good.

(Other embodiments)
In the above embodiment, the throttle mechanism (nozzle portion 14a) in the ejector 14 and the throttle mechanism 17 for the second evaporator 18 are both configured as nozzles, but the throttle mechanism (nozzle portion 14a) in the ejector 14 and the second evaporation are configured. As long as the diaphragm mechanism 17 for the vessel 18 has the same structure, the nozzle 18 is not limited to the nozzle, and for example, another diaphragm mechanism such as a capillary tube may be used.

  In the above-described embodiment, the present invention is applied to the refrigeration cycle apparatus for vehicles. However, the present invention can also be applied to a heating apparatus such as a hot water supply apparatus and a cooling apparatus such as a refrigeration / refrigeration apparatus including a vehicle-mounted type and a stationary type.

In the above embodiment, the refrigerant pressure on the high pressure side is less than the critical pressure, and the refrigerant is a hydrocarbon-based natural refrigerant or a fluorocarbon refrigerant, but carbon dioxide (CO ₂ ) refrigerant is used. It may be configured as a critical pressure cycle. In this case, the condenser 12 can be implemented as a radiator. In the said embodiment, although each apparatus, such as the evaporators 15 and 18, is set as the independent structure, you may comprise the evaporators 15 and 18 integrally, for example.

It is a schematic diagram which shows the vapor | steam compression cycle using the ejector in 1st Embodiment of this invention. It is a figure explaining the relationship between the dryness of the refrigerant | coolant in a throttle structure, and a weight flow rate, A solid line shows the relationship in a nozzle, and a broken line is a figure which shows the relationship in a capillary tube.

Explanation of symbols

10 Vapor Compression Cycle Using Ejector 11 Compressor 12 Condenser (Heat Exchanger)
13 Thermal expansion valve 14 Ejector 14a Nozzle part (throttle part)
14b Refrigerant suction port 14c Mixing part 14d Diffuser part (Pressure raising part)
15 First evaporator 16 Refrigerant branch flow path 17 Throttle mechanism 18 Second evaporator

Claims (2)

A compressor (11) for sucking and compressing refrigerant;
A heat exchanger (12) for cooling the refrigerant discharged from the compressor (11);
A throttle part (14a) for decompressing and expanding the refrigerant on the downstream side of the heat exchanger (12), and a refrigerant suction port (14b) through which the refrigerant is sucked into the interior by the high-speed refrigerant flow injected from the throttle part (14a) And a mixing part (14c) for mixing the high-speed refrigerant flow and the suction refrigerant from the refrigerant suction port (14b), and converting the velocity energy of the refrigerant flow mixed in the mixing part (14c) into pressure energy. An ejector (14) having a booster (14d);
A first evaporator (15) connected to the downstream side of the ejector (14) and discharging the refrigerant to the compressor (11) side;
A second evaporator (18), which is arranged in the refrigerant branch flow path (16) branched from the upstream of the ejector (14) to the refrigerant suction port (14b) and connected to the refrigerant suction port (14b). When,
An ejector provided with a throttle mechanism (17) disposed in the refrigerant branch passage (16) on the upstream side of the second evaporator (18) and depressurizing the refrigerant flowing into the second evaporator (18). In the vapor compression cycle using
The throttle mechanism (17) has the same configuration as the throttle portion (14a) of the ejector (14), and is a vapor compression cycle using an ejector.   The vapor compression cycle using an ejector according to claim 1, wherein the throttle section (14a) and the throttle mechanism (17) are constituted by nozzles.

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