JP4420892B2 - Refrigeration air conditioner - Google Patents

Description

  The present invention relates to an air conditioner configured by connecting a heat-source side unit and a load-side unit using an existing refrigerant pipe, and in particular, a foreign substance mainly composed of old refrigeration oil washed and recovered from the pipe. The present invention relates to a technique for separating and collecting in a recovery container.

  In pipe cleaning for the purpose of reusing existing pipes in refrigeration and air-conditioner replacement, mainly mineral oil and other residues that were present in the existing pipes recovered by pipe cleaning return to the compressor to the new refrigerant circuit. It is necessary to separate and recover residues such as mineral oil so that they do not flow. Refrigerating machine oil such as mineral oil used for CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) containing chlorine before replacement is a new refrigerant HFC system (hydrofluorocarbon) that does not contain chlorine after replacement. This is because they are not compatible with each other. If a large amount of old refrigerating machine oil remains in the refrigerating cycle, there is a possibility that foreign matter (contamination) may occur and problems such as breakage of the compressor may occur.

  Therefore, a technology for separating and recovering foreign matter (mainly old refrigeration machine oil) collected by pipe cleaning has been developed. For example, an accumulator is used as a means for separating refrigerant and foreign matter, and the separated and collected foreign matter is used. Some are collected in a collection container provided in the lower part of the accumulator (see, for example, Patent Document 1). In addition, as a technology to collect the separated and collected foreign matter in a collection container using an accumulator as a means for separating the refrigerant and foreign matter, a pipe for degassing the collection container is connected to the accumulator outlet pipe in order to increase the oil recovery rate. There is one that uses the suction effect improvement for the pipe pressure loss differential pressure (see, for example, Patent Documents 2, 3, and 4).

JP 2003-302127 A (FIGS. 1 and 2) Japanese Patent Laid-Open No. 2004-069101 (FIGS. 1 and 3) Japanese Patent Laying-Open No. 2004-085037 (FIGS. 1 and 2) Japanese Patent Laying-Open No. 2004-2119016 (FIGS. 1 and 2)

  In the technology that uses a conventional accumulator as a separator / collector and collects the foreign matter collected in the accumulator in a collection container, the collection container is installed below the accumulator as the driving force for collecting the foreign matter, and only the head difference is used. . However, due to the installation space restriction in the heat source unit, it is difficult to take a large head difference, the suction force is weak, and it takes a long time to collect and there is a problem that the workability is deteriorated. In particular, when the outside air temperature during the heating period is low, the oil viscosity increases with a decrease in the temperature of the oil, which is the main component of the foreign matter, and this tendency is prominent. The viscosity of the oil tends to increase rapidly with a decrease in temperature.

  Further, in the technique of collecting the foreign matter collected in the accumulator using a conventional accumulator as a separation and collection device in the collection container, the accumulator outlet side (compressor suction side) and the collection container are used to increase the suction force for collecting the foreign matter. Was connected to the gas vent pipe. For this reason, the foreign matter in the collection container may overflow and return to the compressor in a large amount. In order to prevent this, a float valve, a viewing window, and the like have been provided. However, the float valve is expensive, and when the float valve does not operate properly, the mineral oil may overflow and return to the compressor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a refrigeration air-conditioning apparatus that can at least collect foreign matter in a short time.

The refrigerating and air-conditioning apparatus according to the present invention is an air conditioner in which a heat source side unit and a load side unit are connected by an existing refrigerant pipe, wherein the heat source side unit includes an accumulator that separates and collects foreign matter in the existing pipe, and A recovery container for recovering foreign matter separated by the accumulator; and a compressor provided on the downstream side of the accumulator; the bottom of the accumulator and the recovery container are connected by a pipe having a valve; The high-pressure side main refrigerant circuit piping from the first to the four-way valve provided downstream thereof and the accumulator or the piping before and after the accumulator are connected by a bypass piping having a bypass valve, and the pressure in the accumulator is periodically Thus, a differential pressure is generated between the accumulator and the collection container.

  In the present invention, the high-pressure side main refrigerant circuit piping from the compressor to the four-way valve provided on the downstream side thereof, and the accumulator or the piping before and after the accumulator are connected by a bypass piping provided with a bypass valve, By opening the bypass valve, the high pressure gas is supplied to the accumulator, so that the pressure in the accumulator increases. As a result, the pressure in the accumulator becomes higher than the internal pressure of the recovery container, and the foreign matter in the accumulator is quickly discharged to the recovery container due to the pressure difference, and the recovery container can recover the foreign object in a short time. It is possible.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a refrigerant circuit configuration of a refrigeration air-conditioning apparatus according to Embodiment 1 of the present invention. In FIG. 1, a heat source side unit 100 includes an accumulator 8, a compressor 1, an oil separator 10, a four-way valve 2, a heat source side heat exchanger 3, and a pressure regulating valve 12, which are connected in order to be on the heat source side. The main circuit of the unit 100 is configured. The load side unit 200 is composed of expansion devices 5a and 5b and load side heat exchangers 6a and 6b. The heat source side unit 100 and the load side unit 200 include the existing liquid refrigerant pipe 13 and the existing gas. The refrigerant pipe 14, the liquid side ball valve 4 and the gas side ball valve 7 are connected.

  In addition, the heat source side unit 100 includes a pressure sensor 16 provided in the low pressure portion, and a temperature sensor 17 that measures the temperature before the accumulator 8 on the suction side of the compressor 1. By providing a pressure sensor and a temperature sensor at the positions 16 and 17 in the figure, it is possible to detect the refrigerant heating degree at the inlet of the accumulator 8. Here, the temperature sensor 17 is positioned on the inlet side of the accumulator 8 in order to control the refrigerant heating degree at the inlet of the accumulator 8 and to realize an operation in which the liquid refrigerant does not return to the accumulator 8. is there. Note that the position of the pressure sensor 16 is not limited to the illustrated position, and may be provided anywhere as long as it is a section from the four-way valve 2 to the suction side of the compressor 1.

  The heat source side unit 100 includes an oil tank 11, and a pipe branching a refrigerant circuit between the lower part of the oil separator 10 and the oil return capillary 18a is connected to the upper part of the oil tank 11. . Another upper part of the oil tank 11 is connected to a compressor suction pipe by a pipe. Further, the lower part of the oil tank 11 is connected to a pipe connected between the oil return capillary 18a and the compressor suction pipe via the electromagnetic valve 15b. Further, the outlet side of the oil separator 10 and the side surface of the accumulator 8 are connected by a bypass pipe 30 provided with a bypass electromagnetic valve 29, and the accumulator removes the high-temperature and high-pressure gas of the compressor 1 by opening the bypass electromagnetic valve 29. 8 can be led. Here, the reason why the low pressure side of the bypass pipe 30 is used as the side surface of the accumulator 8 is that high pressure gas is directly blown onto the refrigerant and oil (details will be described later). Note that the low pressure position of the bypass pipe 30 is not limited to the position shown in the figure, and includes the pipes before and after the accumulator 8, for example, as long as it is a section from the gas vent pipe merging portion 26 to the outlet of the accumulator 8. It may be provided anywhere.

  Next, the configuration of the foreign material recovery apparatus 110 built in the heat source side unit 100 will be described. In addition, the foreign material in this Embodiment is mainly old refrigerating machine oil, and old refrigerating machine oil and the foreign material which remain | survives in existing piping are generically expressed hereafter as a foreign material. The foreign material recovery device 110 is composed of an accumulator 8, a recovery container 9, and piping and valves associated therewith. The accumulator 8 functions as a foreign material separation means, and the foreign material stored in the accumulator 8 is recovered to the recovery container 9. To do.

  The accumulator 8 is connected to an inlet pipe (accumulator inlet pipe 8a) and an outlet pipe (accumulator outlet pipe 8b) of the main refrigerant circuit. The accumulator inlet pipe 8a has an opening located above the accumulator 8, so that the outlet of the pipe faces in the horizontal direction of the pipe wall so that the inflowing gas flows horizontally on the wall or slightly below the horizontal. It is bent. The accumulator outlet pipe 8b has an opening located above the accumulator 8, and does not directly suck liquid unless a large amount of liquid is stored in the accumulator 8. Connected to the bottom of the accumulator 8 are a recovery pipe 24a for recovering foreign matter stored in the accumulator 8, and an oil return pipe 24b for returning oil to the compressor 1 during normal air conditioning operation. The recovery pipe 24a is connected to the upper part of the recovery container 9 through a flow rate adjusting valve 21a and a ball valve 22a. The inlet height of the collection container 9 may be equal to or less than the bottom surface height of the accumulator 8, but the head difference in the position where the bottom surface height of the accumulator 8 is higher uses the head difference when collecting foreign matter. And the collection speed can be increased.

  The oil return pipe 24b is connected to the post-accumulator suction pipe 28 between the accumulator 8 and the compressor 1 via the flow rate adjusting valve 21b. The oil return pipe 24b is bifurcated and connected to the post-accumulator suction pipe 28 at two locations, upper and lower. This is to cope with changes in the liquid level of the accumulator 8, and is usually connected downward because the liquid level is low. The oil is returned through the pipe, but when the liquid level becomes transiently high, the oil is also returned from the connecting pipe located above, so that a large amount of oil accumulates in the accumulator 8 and the compressor 1 When it is necessary to return the oil quickly, it is possible to respond by increasing the oil return speed.

  The recovery pipe 24a and the oil return pipe 24b are pipes for flowing liquid and are thinner than the main refrigerant pipe, and the recovery container 9 is installed vertically downward, so that foreign matter stays in the pipe when collecting the foreign matter. However, it does not remain on the main refrigerant circuit side. In addition, the part from the recovery pipe 24a to the oil return pipe 24b branching to the flow rate adjusting valve 21b has no staying part such as a trap, and the branching part is installed vertically downward. There is no possibility that the foreign matter will return to the compressor 1 after the foreign matter recovery operation.

  A degassing pipe 25 is provided at the upper part of the collection container 9 for sucking in foreign substances when collecting the foreign substances. The degassing pipe 25 is connected to the pre-accumulator suction pipe 27 via an electromagnetic valve 15c. The degassing pipe 25 is connected to the horizontal to vertical angle with respect to the pre-accumulator suction pipe 27, that is, a position higher than the horizontal. This prevents the liquid refrigerant from flowing down to the collection container 9 through the gas vent pipe 25 when the liquid refrigerant transiently flows in the pre-accumulator suction pipe 27.

  When the gas vent pipe 25 is returned to the downstream side of the accumulator 8, the recovery container 9 overflows when the liquid refrigerant is temporarily returned in a transient state of operation, etc., and the foreign matter directly enters the compressor 1. There is a possibility of returning. When foreign matter returns to the compressor 1, it cannot be recovered, and a large repair such as replacement of the compressor 1 must be performed. Therefore, in the present embodiment, by returning the gas vent pipe 25 to the front of the accumulator 8, even if the recovery container 9 overflows, foreign matter does not return to the compressor 1 and high safety is ensured. be able to.

Next, the principle of foreign substance recovery will be described with reference to FIG.
FIG. 2 is an enlarged view of the foreign material recovery apparatus 110 including the accumulator 8 and the recovery container 9 of FIG. In FIG. 2, valves that are not directly related to the explanation of the principle of foreign matter recovery are omitted.

  In FIG. 2, the head difference from the upper end of the collection container 9 to the bottom surface of the accumulator 8 (the height of the flow path through which liquid foreign matter flows) is H [m], and the static pressure in the gas vent pipe merging portion 26 is P1 [Pa]. The static pressure in the accumulator 8 is P2 [Pa], the static pressure in the collection container 9 is P3 [Pa], and the static pressure at the junction of the oil return pipe 24b and the post-accumulator suction pipe 28 is P4 [Pa]. . Further, the flow rate of oil flowing in the recovery pipe 24a is Vo [m / s], and the pressure loss of the recovery pipe 24a is ΔP [pa]. Of the pipe pressure loss in the recovery circuit from the bottom surface of the accumulator 8, which is a foreign substance recovery circuit, to the gas vent pipe merging portion 26, the problem is the recovery pipe 24a through which high-viscosity oil that is the main component of the foreign substance flows. The pressure loss of the gas vent pipe 25 through which only the low-viscosity gas refrigerant flows, which is the same flow rate as this, is so small as to be relatively negligible due to the small flow rate. Here, for simplification, it is treated as P1≈P3. ,explain.

  When the upper end of the collection container 9 is used as a reference for height, Equation (1) is derived from Bernoulli's theorem.

  When formula (1) is transformed, formula (2) is obtained.

As can be seen from equation (2), in order to increase the foreign matter recovery rate,
(1) If the differential pressure between P2 and P3 is increased, that is, P3 is fixed, the pressure at P2 is increased (from the first term on the right side)
(2) Increase the head difference H (from the second term on the right side),
(3) A method can be considered that reduces the pressure loss of the recovery pipe (from the third term on the right side).

Therefore, in the present embodiment, the foreign matter recovery rate is increased by the synergistic effects of (1) to (3) above.
First, in order to increase the differential pressure between P2 and P3, the internal pressure of the accumulator 8 was increased (details will be described later).
Second, the head difference H may be 0 or more, that is, the bottom surface of the accumulator 8 may be equal to or higher than the inlet height of the collection container 9. A maximum recovery speed can be obtained by setting the maximum as far as the layout constraint permits.
Thirdly, in the present embodiment, in order to reduce the pressure loss in the recovery pipe, the pipe diameter of the recovery pipe 24a is as large as possible, and the length of the valves to be interposed is also as small as possible in the pressure loss coefficient. It was decided to select.

  By the way, the foreign material recovery operation in the above-described refrigeration and air conditioning apparatus is performed after the unit is constructed on site and the foreign material in the existing piping is separated and recovered by the accumulator 8 by the cleaning operation. After the explanation, the foreign substance recovery operation will be explained.

  In the cleaning operation, first, the compressor 1 is activated to start the cleaning operation. Here, the operation when operating in the cooling cycle will be described. When the compressor 1 is operated, the high-temperature and high-pressure gas refrigerant separates the refrigeration oil taken out from the compressor 1 by the oil separator 10, and the refrigerant gas is condensed and liquefied by the heat source side heat exchanger 3 via the four-way valve 2. Is done. The refrigerating machine oil separated by the oil separator 10 flows into the suction pipe of the compressor 1 through the oil return capillary 18a and returns to the compressor 1 together with the refrigerant. The refrigerant condensed in the heat source side heat exchanger 3 becomes a liquid or a gas-liquid two-phase refrigerant with low dryness. This gas-liquid two-phase refrigerant is throttled to an intermediate pressure by the pressure regulating valve 12. Here, the pressure regulating valve 12 is controlled to be lower than the pressure resistance of the existing piping. The intermediate-pressure gas-liquid two-phase refrigerant or liquid single-phase refrigerant flows through the liquid refrigerant pipe 13 and is throttled to a low pressure by the throttle devices 5a and 5b. In the load-side heat exchangers 6a and 6b, the low-pressure gas-liquid two-phase refrigerant takes heat from the surroundings and cools it, and evaporates to become a gas refrigerant and flows through the gas refrigerant pipe 14. The refrigerant flowing through the gas refrigerant pipe 14 enters the accumulator 8 through the four-way valve 2 together with liquid foreign matters such as mineral oil. In the accumulator 8, the refrigerant gas and the foreign matter are separated, the refrigerant gas returns to the compressor 1, and the liquid foreign matter stays in the accumulator 8. The flow rate adjusting valve 21a and the electromagnetic valve 15c are opened only when collecting foreign matter, and are closed during other operating states. Further, in the cleaning operation, not only the cooling operation but also the cleaning operation of the heating operation can similarly cause liquid foreign matter to stay in the accumulator 8.

  Next, the foreign substance recovery operation will be described. In the initial state of the foreign matter recovery operation, the inside of the recovery container 9 is evacuated, and the foreign matter stored in the accumulator 8 moves to the recovery container 9 when the flow rate adjustment valve 21a is opened. The foreign matter recovery time greatly depends on the viscosity of the oil that is the main component of the foreign matter, and can be predicted from the outside air temperature. By setting the recovery time with a margin of, for example, 1.5 times the estimated time, the foreign matter in the accumulator 8 can be completely moved to the recovery container 9.

  When the flow rate adjusting valve 21a is opened and the foreign matter is moved to the collection container 9, the accumulator 8 and the collection container 9 gradually become equalized. Therefore, in the present embodiment, with the flow rate adjustment valve 21a and the electromagnetic valve 15c being closed once, the bypass electromagnetic valve 29 is further opened to guide the high-pressure discharge gas on the compressor 1 side to the accumulator 8, and the accumulator 8 By increasing the pressure on the side, a differential pressure is generated between the accumulator 8 (high pressure) and the collection container 9 (low pressure) (P2-P3). Then, the bypass electromagnetic valve 29 is closed, the electromagnetic valve 15c is opened, and the amount adjusting valve 21a is opened to move the foreign matter in the accumulator 8 to the collection container 9 and collect the foreign matter. At this time, the gas in the collection container 9 is sent out to the pre-accumulator suction pipe 27 via the electromagnetic valve 15c and discharged. However, even in this case, the differential pressure between the accumulator 8 and the collection container 9 decreases with time. Therefore, the opening / closing operation of the solenoid valve 15c and the bypass solenoid valve 29 is repeated at appropriate intervals (closing the solenoid valve 15c and opening the bypass solenoid valve 29, opening the solenoid valve 15c and closing the bypass solenoid valve 29), and the accumulator 8 By changing the internal pressure periodically, a differential pressure is generated between the accumulator 8 (high pressure) and the collection container 9 (low pressure).

  Moreover, by opening the bypass solenoid valve 29 and supplying the high-temperature and high-pressure gas directly into the accumulator 8 as described above, the temperature in the accumulator 8 can be raised and the refrigerant can be gasified even in a low-temperature environment. Thereby, it is possible to prevent the liquid refrigerant from moving to the recovery container 9 during the foreign substance recovery operation. Furthermore, it is possible to suppress the increase in the viscosity of the oil by the bypassed high-temperature gas and increase the moving speed to the collection container 9.

  FIG. 3 is a characteristic diagram showing an example of pressure fluctuation in the accumulator 8 when the opening / closing operation of the solenoid valve 15c and the bypass solenoid valve 29 is repeated at a predetermined cycle. In consideration of the pressure fluctuation as shown in the figure, the time interval for opening and closing the solenoid valve 15c and the bypass solenoid valve 29 is suitably 30 to 120 seconds.

  FIG. 4 is a characteristic diagram showing an example of a characteristic in which the moving speed of the oil when the switching control of the solenoid valves 15c and 29 is performed and the moving speed of the oil when the switching control is not performed. is there. As can be seen from the figure, the moving speed is faster when the switching control is performed.

  As described above, in the first embodiment, the high-pressure side main refrigerant circuit piping from the compressor 1 to the four-way valve 2 and the accumulator 8 are connected by the bypass piping provided with the bypass electromagnetic valve 29, By opening the bypass electromagnetic valve 29, the high pressure gas is supplied to the accumulator 8, whereby the pressure in the accumulator 8 increases. As a result, the pressure in the accumulator 8 becomes higher than the internal pressure of the recovery container 9 (P2> P3), and the foreign matter in the accumulator 8 is quickly discharged to the recovery container 9 due to the pressure difference. Can collect foreign matter in a short time.

  Further, the bypass electromagnetic valve 29 is controlled to open and close at a predetermined cycle, and the pressure in the accumulator 8 is periodically changed, so that the difference between the accumulator 8 (high pressure) and the recovery container 9 (low pressure) is continuously increased. Since the pressure is generated, it is possible to prevent the state in which the differential pressure between the accumulator 8 and the collection container 9 decreases with time.

Embodiment 2. FIG.
Further, as a method for generating a differential pressure between the accumulator 8 and the collection container 9, a pressure change by changing the driving frequency of the compressor 1 can also be used. For example, when the drive frequency of the compressor 1 is lowered, the pressure on the suction port side of the compressor 1 is increased, and the pressure in the accumulator 8 is increased. Further, when the drive frequency of the compressor 1 is increased, the pressure on the suction port side of the compressor 1 is decreased, and the pressure in the accumulator 8 is decreased. Thus, the characteristic as shown in FIG. 3 is obtained by varying the driving frequency of the compressor 1. By the way, since the recovery speed increases as the differential pressure (P2-P3) increases, it is desirable that the frequency change is as large as possible. However, there is a possibility that the liquid refrigerant is sucked into the compressor 1 by reducing the frequency too much. Therefore, it is appropriate to control the frequency change between 60 and 90 Hz.

  Further, by using the above-described solenoid valve 15c as a check valve, switching control during the recovery operation becomes unnecessary, and at the same time, an exhaust pressure effect can be expected when the pressure in the recovery device rises after the recovery operation ends. .

The refrigerant circuit figure of the refrigerating air-conditioning apparatus of Embodiment 1 of this invention. Explanatory drawing of the oil collection | recovery apparatus of Embodiment 1 of this invention. The characteristic view which showed the example of the pressure fluctuation in an accumulator when opening / closing operation | movement of a solenoid valve (15c) and a bypass solenoid valve (30) was repeated. The characteristic view which showed an example of the characteristic which contrasted when the switching control of a solenoid valve (15c, 30) was performed, and the moving speed of the oil when not performing the switching control.

Explanation of symbols

1 compressor, 2 four-way valve, 3 heat source side heat exchanger, 4 liquid side ball valve, 5a, 5b pressure regulating valve, 6a, 6b load side heat exchanger, 7 gas side ball valve, 8 accumulator, 8a accumulator inlet pipe 8b Accumulator outlet pipe, 9 Recovery container, 10 Oil separator, 11 Oil tank, 12 Pressure regulating valve, 13 Liquid refrigerant pipe, 14 Gas refrigerant pipe, 15a, 15b, 15c Solenoid valve, 16 Pressure sensor, 17 Temperature sensor, 18a Capillaries for oil return, 21a, 21b Flow rate adjusting valve, 22a Ball valve, 23 Pressure relief valve, 24a Recovery pipe, 24b Oil return pipe, 25 Gas vent pipe, 26 Gas vent pipe merge section, 27 Inlet pipe before accumulator, 28 Suction pipe after accumulator, 29 Bypass solenoid valve, 30 Bypass pipe, 100 Heat source side unit, 110 Foreign matter recovery device 200 load-side unit.

Claims (5)

In an air conditioner in which a heat source unit and a load unit are connected by an existing refrigerant pipe,
The heat source side unit is:
An accumulator that separates and collects foreign matter in existing piping;
A collection container for collecting foreign matter separated by the accumulator;
A compressor provided on the downstream side of the accumulator,
The bottom of the accumulator and the collection container are connected by a pipe provided with a valve,
The high-pressure side main refrigerant circuit piping from the compressor to the four-way valve provided downstream thereof, and the accumulator or the piping before and after the accumulator are connected by a bypass piping provided with a bypass valve,
A refrigerating and air-conditioning apparatus characterized in that a differential pressure is generated between the accumulator and the collection container by periodically varying the pressure in the accumulator . The refrigerating and air-conditioning apparatus according to claim 1, wherein the bypass valve is configured by an electromagnetic valve, and the electromagnetic valve is controlled to open and close at a predetermined cycle. In an air conditioner in which a heat source unit and a load unit are connected by an existing refrigerant pipe,
The heat source side unit is:
An accumulator that separates and collects foreign matter in existing piping;
A collection container for collecting foreign matter separated by the accumulator;
A compressor provided on the downstream side of the accumulator,
The bottom of the accumulator and the collection container are connected by a pipe provided with a valve,
Fluctuation control is performed on the driving frequency of the compressor , and the pressure in the accumulator is periodically varied to generate a differential pressure between the accumulator and the recovery container. Air conditioner. The low-pressure main refrigerant circuit pipe extending from a four-way valve provided on the downstream side of the compressor to the accumulator and the recovery container are connected by a gas vent pipe provided with an electromagnetic valve. Refrigeration air conditioner in any one of -3. The low-pressure main refrigerant circuit pipe extending from a four-way valve provided on the downstream side of the compressor to the accumulator and the recovery container are connected by a gas vent pipe provided with a check valve. The refrigeration air conditioning apparatus in any one of 1-3.

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