JP2006226590A - Refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent degradation of evaporation performance by refrigerator oil in an evaporator by surely lubricating an expander and a compressor. <P>SOLUTION: A refrigeration cycle is composed by sealing a refrigerant and refrigerator oil in a circuit with the compressor, a radiator, the expander and the evaporator connected in this order; an evaporator body 30 of the evaporator is provided with an entrance header 31 having an oil accumulation part 34 diving a refrigerant passage into a plurality of parts and separating the refrigerator oil 40; an oil feed pipe 35 is mounted in a lower part of the entrance header 31; and the oil feed pipe 35 is made to communicate with an exit header 33. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigeration cycle apparatus, and more particularly to a refrigeration cycle apparatus provided with energy recovery means for recovering expansion energy when a refrigerant expands.

  In the refrigeration cycle apparatus, a compressor, a radiator, and an evaporator are connected in order to enclose a refrigerant, and an expansion mechanism is disposed between the radiator and the evaporator to expand the refrigerant. An expansion valve, a capillary tube, or the like is used as the expansion mechanism. On the other hand, when the difference between the high pressure and the low pressure in the refrigeration cycle is large, an expansion machine is used instead of the expansion mechanism, and the expansion energy of the refrigerant in the expansion machine is converted into rotational energy to generate power or power. In this example, the efficiency of the refrigeration cycle apparatus is improved (see, for example, Patent Document 1).

Since such an expander has sliding parts such as bearings, it is necessary to lubricate them, and refrigeration oil circulating in the refrigeration cycle is supplied to the expander. On the other hand, the refrigerating machine oil discharged from the expander flows into the evaporator together with the refrigerant, and lowers the evaporation capability in the evaporator. Therefore, an example is disclosed in which the refrigerant discharged from the expander and the refrigerating machine oil are separated by an oil separator, and the refrigerant is supplied to the evaporator and the refrigerating machine oil is supplied to the compressor (see, for example, Patent Document 2). ).
JP 2000-329416 A JP 2003-139420 A

  However, in the configuration in which an oil separator is separately provided at the outlet of the expander as in the conventional example, the refrigeration cycle apparatus is increased in size. In addition, when oil is not stored in the oil separator, most of the refrigerant flows through a bypass pipe provided by bypassing from the oil separator to the compressor side, so that the evaporation performance of the evaporator is significantly reduced. is there.

  An object of this invention is to provide the refrigerating-cycle apparatus which prevents inflow of refrigerating machine oil to an evaporator with a simple structure, and does not reduce evaporation performance.

  In order to solve the above-described problems, the refrigeration cycle apparatus of the present invention includes a refrigerant, refrigeration oil, and a refrigeration cycle enclosed in a circuit in which a compressor, a radiator, an expander, and an evaporator are connected in order. In the evaporator, the refrigerant flow path is divided into a plurality and an inlet header for separating the refrigerating machine oil is provided.

  According to such a configuration, it is possible to suppress the inflow of refrigerating machine oil to the evaporator with a simple configuration that shares the inlet header and the oil separator for diverting the refrigerant, thereby improving the performance of the evaporator. be able to. In particular, reliable lubrication with refrigerating machine oil for an expander having a sliding portion for recovering the expansion energy of the refrigerant and ensuring the performance of a high evaporator can be achieved at the same time.

  Furthermore, it is desirable to provide an outlet header in the evaporator and an oil feeding pipe below the inlet header so that the oil feeding pipe communicates with the outlet header. According to such a configuration, the refrigerating machine oil can be supplied to the compressor without interfering with the performance of the evaporator and further circulated in the refrigerating cycle.

Furthermore, it has a liquid level detection means for detecting the liquid level of the refrigerating machine oil provided in the inlet header, and an oil supply pipe opening / closing means for controlling the opening and closing of the communication of the oil supply pipe by the liquid level of the refrigerating machine oil detected by the liquid level detection means. It is desirable. According to such a configuration, when the amount of refrigerating machine oil is small, it is possible to prevent most of the refrigerant from flowing into the oil feeding pipe, and it is possible to prevent a decrease in evaporation performance.

  Further, it is desirable that the liquid level detecting means is a float made of a material having a specific gravity smaller than the specific gravity of the refrigerating machine oil and larger than the specific gravity of the liquid refrigerant. According to such a configuration, the liquid level detection of the refrigeration oil can be realized with a simple configuration.

  Furthermore, when the oil feed pipe opening / closing means is a float and the liquid level of the refrigerating machine oil at the inlet header is below a predetermined liquid level, it is desirable to close the oil feed pipe with the float. According to such a configuration, the flow control of the refrigerating machine oil to the oil feeding pipe can be reliably performed with a simple configuration.

  Furthermore, it is desirable that the refrigerant is carbon dioxide. According to such a configuration, it is possible to realize a highly efficient refrigeration cycle apparatus that is friendly to the environment and collects the expansion energy of the refrigerant in the expander that requires lubrication with refrigeration oil.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the refrigerating-cycle apparatus which can prevent the inflow of the refrigerating machine oil to an evaporator with simple structure, and does not reduce evaporation performance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 2 is a configuration diagram of the refrigeration cycle apparatus according to the first embodiment of the present invention. The refrigeration cycle apparatus 10 forms a refrigeration cycle 20 in which a refrigerant is circulated by sequentially connecting a compressor 12, a radiator 14, an expander 16, and an evaporator 18 in series. In the embodiment of the present invention, the refrigerant is filled with carbon dioxide, and the refrigerant oil for the purpose of lubricating the bearings and other mechanisms of the compressor 12 and the expander 16 is polyalkylene glycol (hereinafter referred to as PAG). Is described).

  In the refrigeration cycle apparatus 10, the refrigerant circulates in the direction indicated by the arrow A. The compressor 12 compresses the carbon dioxide of the refrigerant to a high temperature and high pressure supercritical state exceeding the critical point, and the heat is released in the radiator 14 while maintaining the pressure, thereby lowering the temperature. The expander 16 converts the expansion energy of the high-pressure refrigerant into mechanical energy. Specifically, volume change due to expansion is converted into rotational energy, and electric power is generated by a generator 24 connected to the expander 16 by a drive shaft 22. Specific examples of the expander 16 include a scroll type and a vane rotary type. The electric power generated by the generator 24 can be used as driving electric power for the compressor 12 and the fan 26 of the evaporator 18 through the electric power line 28 shown by the broken line in FIG. Further, in the evaporator 18, the refrigerant that has passed through the expander 16 and has become low temperature and low pressure takes heat from the surroundings and evaporates into a gas phase, and returns to the compressor 12. The refrigerating machine oil enclosed in the refrigerating cycle 20 circulates in the refrigerating cycle 20 together with the refrigerant, and lubricates or cools the mechanical parts such as the compressor 12 and the expander 16.

Next, the evaporator 18 will be described in more detail. FIG. 1 is a cross-sectional view showing the configuration of the evaporator of the refrigeration cycle apparatus according to the first embodiment of the present invention. The evaporator main body 30 includes an inlet header 31 into which the gas-liquid two-phase refrigerant expanded by the expander 16 enters, an evaporator heat exchanging section 32, and an outlet header 33 provided to face the refrigerant flow path of the inlet header 31. And constitutes a so-called one-pass circuit evaporator. An oil reservoir 34 is provided below the inlet header 31 via a partition 42, and an oil feed pipe 35 that connects the oil reservoir 34 and the outlet header 33 is further provided. The evaporator heat exchanging section 32 includes a plurality of refrigerant pipes 36 made of, for example, copper pipes through which the refrigerant passes, and fins 37 as enlarged heat transfer surfaces provided on the outer periphery of the refrigerant pipe 36. The outside air is circulated between the fins 37 so that heat is exchanged between the outside air and the refrigerant.

  The refrigerant expanded in the expander 16 and in a gas-liquid two-phase state is discharged into the inlet header 31 from the refrigerant inlet pipe 38 provided in the inlet header 31. The PAG of the refrigerating machine oil and the carbon dioxide of the refrigerant are two-phase separated at −50 ° C. or higher, and the specific gravity of PAG is larger than that of carbon dioxide at −10 ° C. or higher. Therefore, the refrigerant in the gaseous state and the liquid state and the refrigeration oil in the liquid state dispersed in the refrigerant are discharged to the inlet header 31, and the refrigeration oil 40 is stored in the oil storage part 34 of the inlet header 31. Further, a part of the liquid refrigerant in the refrigerant is separated from the gas refrigerant and stored in the upper part of the refrigerating machine oil 40. As a method of actively separating the refrigerating machine oil from the refrigerant, the arrangement and shape of the refrigerant inlet pipe 38 or the shape of the inlet header 31 are changed so that the centrifugal separation is performed using the specific gravity difference in the inlet header 31. It is also possible.

  The refrigerant discharged to the inlet header 31 and separated from the refrigerating machine oil is divided into a plurality of refrigerant pipes 36 and flows to the outlet header 33 due to a pressure difference. While passing through the refrigerant pipe 36, the refrigerant exchanges heat with the outside air and evaporates, and the refrigerant only in the gaseous state joins again at the outlet header 33. The merged refrigerant is sucked into the compressor 12 through a refrigerant outlet pipe 41 provided at the lower part of the outlet header 33. Here, the refrigerant oil 40 from the oil feed pipe 35 and the refrigerant in the outlet header 33 join the refrigerant outlet pipe 41 and are sucked into the compressor 12.

  As described above, according to the first embodiment of the present invention, since the inlet header 31 for diverting the refrigerant and the oil reservoir 34 as an oil separator are shared, the evaporator main body 30 can be configured with a simple configuration. Inflow of the refrigeration oil into the refrigerant pipe 36 can be suppressed. Therefore, an oil film of refrigeration oil or the like is not formed on the inner wall of the refrigerant pipe 36. Therefore, the evaporation performance in the evaporator main body 30 can be improved without hindering the heat transfer performance of the refrigerant pipe 36. Therefore, even in a refrigeration cycle apparatus using an expander using a carbon dioxide or the like as a refrigerant and having a sliding portion for recovering the expansion energy of the refrigerant, reliable lubrication with the compressor oil between the compressor and the expander is possible. And higher performance of the evaporator can be ensured.

(Second Embodiment)
FIGS. 3A and 3B are cross-sectional views showing the configuration of the main part of the evaporator of the refrigeration cycle apparatus according to the second embodiment of the present invention. In particular, the vicinity of the oil reservoir 34 of the inlet header 31 is enlarged. FIG.

  As shown in FIGS. 3A and 3B, an oil reservoir 34 is provided in the inlet header 31 of the evaporator body 30, and an oil feed pipe 35 is provided in the oil reservoir 34 so as to open. In addition, a float 43 serving as a liquid level detecting means for detecting the liquid level of the refrigerating machine oil 40 is provided in the oil reservoir 34. The float 43 is made of a material having a specific gravity smaller than the specific gravity of the refrigerating machine oil 40 and larger than the specific gravity of the liquid refrigerant. The float 43 is attached to a float support plate 44 serving as an oil feed pipe opening / closing means, and is configured so that the float support plate 44 can move up and down in a guide tube 45 provided in the oil reservoir 34. Further, a stopper 46 is provided on the upper part of the float 43 to regulate the upper position of the float 43. The guide tube 45 is provided with an opening 47 that opens to the oil feed pipe 35, and the float support plate 44 can control the communication between the opening 47 and the oil feed pipe 35.

FIG. 3A is a diagram illustrating a state where the storage level of the refrigerating machine oil 40, that is, the refrigerating machine oil 40 is large, and FIG. FIG.
As shown in a), when the storage amount of the refrigerating machine oil 40 is large, the float 43 rises and the float support plate 44 also rises, and the opening 47 and the oil feeding pipe 35 communicate with each other to freeze the outlet header 33. Machine oil 40 is discharged. On the other hand, as shown in FIG. 3B, when the storage amount of the refrigerating machine oil 40 is reduced, the float 43 and the float support plate 44 are lowered to close the communication between the opening 47 and the oil feed pipe 35, and the oil feed pipe The discharge of the refrigerating machine oil 40 from 35 is closed.

  In this way, the float 43 is made of a material having a specific gravity smaller than the specific gravity of the refrigerating machine oil 40 and larger than the specific gravity of the liquid refrigerant, and is used as a liquid level detection means of the refrigerating machine oil 40, so The liquid level of the refrigerating machine oil 40 can be reliably detected without being affected by the liquid refrigerant. Therefore, it is possible to prevent the refrigerant from flowing into the oil feeding pipe 35 when the amount of the refrigerating machine oil 40 is small, and it is possible to prevent a decrease in evaporation performance.

  In the second embodiment of the present invention, the float support plate 44 attached to the float 43 is moved up and down by the rising and lowering of the float 43 so as to control the communication with the oil feed pipe 35. The position of the float 43 may be detected electromagnetically, and a flow path opening / closing valve such as an electromagnetic valve provided separately in the route of the oil feeding pipe 35 may be controlled. Furthermore, as the liquid level detection means, an optical transmitter / receiver may be provided to serve as the detection means.

(Third embodiment)
FIG. 4 is a sectional view showing the configuration of the evaporator of the refrigeration cycle apparatus in the third embodiment of the present invention. The basic configuration of the evaporator body 50 is the same as that of the first embodiment of the present invention shown in FIG. In the first embodiment of the present invention, a so-called one-pass circuit evaporator is described in which the refrigerant is divided at the inlet header and heat-exchanged, and then merged again at the outlet header and flows into the evaporator. The third embodiment of the present invention relates to a so-called multi-pass circuit evaporator in which refrigerant travels back and forth between headers.

  As shown in FIG. 4, the evaporator body 50 includes a first evaporator 51 and a second evaporator 52. The first evaporator 51 includes a first evaporator inlet header 53, a first evaporator outlet header 54, and a first evaporator heat exchange unit 55. The first evaporator heat exchanging section 55 includes a plurality of refrigerant tubes 56 and fins 57 provided around the refrigerant tubes 56. On the other hand, the second evaporator 52 includes a second evaporator inlet header 58, a second evaporator outlet header 59, and a second evaporator heat exchange unit 60. The second evaporator heat exchange unit 60 includes a plurality of refrigerant pipes. 56 and fins 57 provided around it.

  Therefore, the refrigerant from the expander enters the first evaporator inlet header 53 through the refrigerant inlet pipe 61, and the first evaporator heat exchange section 55, the first evaporator outlet header 54, the second evaporator inlet header 58, the second evaporator. The refrigerant is sucked into the compressor from the refrigerant outlet pipe 63 via the evaporator heat exchange section 60 and the second evaporator outlet header 59 in this order. Therefore, the inlet header of the evaporator body 50 is the first evaporator inlet header 53, and the outlet header is the second evaporator outlet header 59. The first evaporator outlet header 54 and the second evaporator inlet header 58 are partitioned from each other and communicated by the refrigerant communication portion 62. The first evaporator inlet header 53 and the second evaporator outlet header 59 are partitioned from each other and communicated by the oil communication portion 64.

  In the first evaporator inlet header 53, as in the first embodiment, an oil reservoir 65 is formed by a partition portion 67, and an oil communication portion 64 is provided at the bottom of the oil reservoir 65. As described in the first embodiment, the refrigerant mixed with the refrigerating machine oil flowing into the first evaporator inlet header 53 is separated into the refrigerant and the refrigerating machine oil in the first evaporator inlet header 53, Refrigerating machine oil 66 is stored in the oil storage unit 65. The refrigerating machine oil 66 stored in the oil storage section 65 falls from the oil communication section 64 to the second evaporator outlet header 59 and joins and compresses the refrigerant in the refrigerant outlet pipe 63 provided in the second evaporator outlet header 59. Inhaled into the machine.

  Therefore, even in the evaporator of the multipath circuit in this way, the refrigerating machine oil 66 does not flow into the refrigerant pipe 56 of the evaporator main body 50 by separating the refrigerating machine oil and the refrigerant flowing into the evaporator. The evaporation performance in the evaporator main body 50 can be improved without hindering the heat transfer performance of the refrigerant pipe 56.

  The refrigeration cycle apparatus of the present invention can prevent the inflow of refrigeration oil into the evaporator with a simple configuration and does not deteriorate the evaporation performance, so that the refrigeration cycle apparatus can be applied to uses such as an air conditioner, a water heater, and a refrigerator.

Sectional drawing which shows the structure of the evaporator of the refrigerating-cycle apparatus in the 1st Embodiment of this invention The block diagram of the refrigerating-cycle apparatus in the 1st Embodiment of this invention (A) Sectional drawing which shows the structure of the principal part when there is much refrigeration oil of the evaporator of the refrigerating-cycle apparatus in the 2nd Embodiment of this invention (b) Refrigerating-cycle apparatus in the 2nd Embodiment of this invention Sectional drawing which shows the structure of the principal part when there is much refrigerating machine oil of an evaporator Sectional drawing which shows the structure of the evaporator of the refrigerating-cycle apparatus in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Refrigeration cycle apparatus 12 Compressor 14 Radiator 16 Expander 18 Evaporator 20 Refrigeration cycle 22 Drive shaft 24 Generator 26 Fan 28 Power line 30, 50 Evaporator main body 31 Inlet header 32 Evaporator heat exchange part 33 Outlet header 34, 65 Oil reservoir 35 Oil feed pipe 36, 56 Refrigerant pipe 37, 57 Fin 38, 61 Refrigerant inlet pipe 40, 66 Refrigerating machine oil 41, 63 Refrigerant outlet pipe 42, 67 Partition 43 Float 44 Float support plate 45 Guide cylinder 46 Stopper 47 Opening Part 51 First evaporator 52 Second evaporator 53 First evaporator inlet header 54 First evaporator outlet header 55 First evaporator heat exchange section 58 Second evaporator inlet header 59 Second evaporator outlet header 60 Second Evaporator heat exchange unit 62 Refrigerant communication unit 64 Oil communication unit

Claims (6)

A refrigerant, refrigerating machine oil is enclosed in a circuit in which a compressor, a radiator, an expander, and an evaporator are connected in order to form a refrigeration cycle, and the refrigerant flow path is divided into a plurality of parts in the evaporator. An refrigeration cycle apparatus comprising an inlet header for separating the refrigeration oil. The refrigeration cycle apparatus according to claim 1, wherein an outlet header is provided in the evaporator, an oil feeding pipe is provided at a lower portion of the inlet header, and the oil feeding pipe is communicated with the outlet header. A liquid level detecting means for detecting a liquid level of the refrigerating machine oil provided in the inlet header; and an oil feeding pipe opening / closing means for controlling the opening and closing of the communication of the oil feeding pipe by the liquid level of the refrigerating machine oil detected by the liquid level detecting means. The refrigeration cycle apparatus according to claim 2. 4. The refrigeration cycle apparatus according to claim 3, wherein the liquid level detecting means is a float made of a material having a specific gravity smaller than the specific gravity of the refrigerating machine oil and larger than the specific gravity of the liquid refrigerant. 5. The refrigeration cycle apparatus according to claim 4, wherein the oil feed pipe opening / closing means is a float, and the oil feed pipe is closed by the float when the liquid level of the refrigeration oil in the inlet header is equal to or lower than a predetermined liquid level. The refrigeration cycle apparatus according to any one of claims 1 to 5, wherein the refrigerant is carbon dioxide.

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