JP3762542B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to an air conditioner, and more specifically, a refrigerant capable of phase change between an outdoor unit and a plurality of indoor units, the total number or majority of which is installed below the outdoor unit, is divided into a liquid phase and a gas phase. It is related with the apparatus which made it circulate using the specific gravity difference of this, and the discharge force of the auxiliary pump for cooling installed in the liquid phase pipe | tube, and enabled the cooling operation in each indoor unit.
[0002]
[Prior art]
Conventionally, there is an apparatus as shown in FIG. 6, for example, as an air conditioner that does not require a transfer power of a phase changeable refrigerant, that is, a refrigerant whose state changes between liquid and gas by taking in and out latent heat. However, this apparatus installs the outdoor unit 1 functioning as a condenser at the high position of the building, and the outdoor unit 1 and the heat exchanger 5 of the indoor unit installed in the air-conditioned room at a lower position. The liquid phase pipe 6 and the gas phase pipe 7 are connected to each other, and the liquid radiated and condensed by the heat exchanger 2 of the outdoor unit 1 is supplied to the heat exchanger 5 of the indoor unit through the liquid phase pipe 6 by its own weight. On the other hand, the heat absorbed and evaporated by heat exchange with the indoor air having a high temperature in the heat exchanger 5 of the indoor unit flows into the outdoor unit 1 having a low pressure due to the condensation of the refrigerant through the gas phase pipe 7. Therefore, it is possible to circulate so Next, there is an advantage that the running cost is said that can be suppressed. In addition, 11 is a flow control valve and 18 is a blower.
[0003]
In addition, a receiver tank 8 and an electric pump 9 are incorporated in series in the liquid phase pipe 6 as indicated by a broken line, and the electric pump 9 is connected to the liquid tank 6 based on the liquid level of the refrigerant accumulated in the receiver tank 8 and capable of phase change. There is also an air conditioner configured to be able to circulate a phase-changeable refrigerant even if some indoor units are installed at the same height as the outdoor unit 1 or installed at a higher position, with on / off control. It is well known.
[0004]
[Problems to be solved by the invention]
However, in the air conditioner configured as described above, the in-circuit pressure of the phase-changeable refrigerant is constantly changing due to a change in cooling load, etc., and when the pressure decreases, a part of the refrigerant in the liquid-phase tube is vaporized and bubbles are generated. May occur.
[0005]
In particular, when the cooling operation is started, even if the liquid phase tube is covered with a heat insulating material, the temperature of the liquid phase refrigerant is heated by the outside air and is relatively high, so the outdoor unit starts cooling. When the pressure in the circuit suddenly drops, the refrigerant may foam all at once in the liquid phase tube in response to the pressure drop. In addition, even when the cooling load is small and the amount of circulating refrigerant is small, it is easily affected by outside air, and in such a partial load operation, the refrigerant may foam in the liquid phase tube even if the pressure drops slightly. Further, bubbles may be generated by heat entering from the outside air into equipment provided in the middle of the piping.
[0006]
And the bubble produced | generated in this way makes the circulation of a liquid phase refrigerant | coolant unstable, or makes the branch flow of the liquid phase refrigerant | coolant to each indoor unit unstable. As a result, in an extreme case, an indoor unit in which the refrigerant does not flow occurs, and there is a situation in which the room cannot be sufficiently cooled.
[0007]
In addition, in the air conditioner configured as described above, the liquid-phase refrigerant that has dissipated heat and condensed in the outdoor unit enters the indoor unit, evaporates, and then returns to the outdoor unit. There is a drawback that it is difficult to eliminate it, it is difficult to get out of the adverse effect for a long time, and it is greatly affected. In other words, the air bubbles accumulated at the entrance of the indoor unit on each floor must be taken such that the expansion valve is once fully opened and removed to the outlet side. The refrigerant is also discharged to the outlet side of the indoor unit, so that a so-called liquid back in which the liquid phase refrigerant stays in the gas phase pipe is generated, which also causes a circulation failure of the refrigerant.
[0008]
Accordingly, it is difficult for bubbles to be generated in the liquid phase tube, and it is necessary to be able to easily eliminate the bubbles even if they are generated.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems of the prior art, the present invention provides a liquid-phase pipe provided with an auxiliary pump for cooling between an outdoor unit and a plurality of indoor units, all or a majority of which are installed below the outdoor unit, A refrigerant that can be phase-changed by connecting with a gas phase pipe, using the difference in specific gravity between the liquid phase and the gas phase and the discharge force of the auxiliary pump for cooling, an outdoor unit, a liquid phase pipe, an indoor unit, and a gas phase pipe In the air conditioner configured to circulate in this order and enable the cooling operation using the phase change from the liquid phase to the gas phase of each refrigerant in each indoor unit, the liquid phase tube that reaches the lowest indoor unit relative to the outdoor unit Is provided with a second liquid phase pipe extending from the lower side to the outdoor unit, and a second liquid pump for conveying the refrigerant to the outdoor unit is provided in the second liquid phase pipe, and the outdoor unit is provided during cooling operation. Supplying the refrigerant condensed and liquefied to the indoor unit via the liquid phase pipe, and the second liquid pump The refrigerant is circulated to the second liquid phase pipe to increase the circulation amount of the refrigerant circulating in the liquid phase pipe, and the bubbles generated in the liquid phase pipe can be returned to the outdoor unit. The air conditioner which did it is provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 (during cooling operation) and FIG. In order to facilitate understanding, in these drawings, the same reference numerals are given to the portions having the same functions as those described in FIG .
[0012]
In FIG. 1, reference numeral 1 denotes an outdoor unit that can selectively generate cold and hot heat, for example, an absorption refrigerator, and is installed in a machine room on the roof of a building, for example, inside an evaporator. Heat is exchanged with a refrigerant capable of phase change enclosed in the closed circuit 3, for example, R-134a, which can be easily evaporated when the pressure drops even at a low temperature, through the piped heat exchanger 2.
[0013]
Reference numeral 5 denotes an indoor unit heat exchanger installed on each floor / room of the building, and is connected to the heat exchanger 2 of the outdoor unit 1 by a liquid phase pipe 6 and a gas phase pipe 7 as shown in the figure. The closed circuit 3 is formed.
[0014]
Then, the R-134a of the liquid that is radiated, condensed and discharged by the heat exchanger 2 of the outdoor unit 1 during the cooling operation is stored through the liquid pipe 20 having the on-off valve 15a (opened during the cooling operation). Receiver tank 8, electric pump 9 functioning as a cooling auxiliary pump for supplying R-134a accumulated in the tank to the indoor unit, and cooling / heating switching valve that opens during cooling operation and closes during heating operation 10 is interposed in series, and the first liquid phase pipe 6A that reaches each indoor unit via each expansion valve 11 is branched and extended from a lower portion of the first liquid phase pipe 6A. A receiver tank 12 for storing the liquid R-134a in the lowest part, an electric pump 13 for returning the R-134a stored in the tank to the outdoor unit 1, and a check valve 14 are interposed in series. Liquid that passes through the check valve 14 R-134a is composed of a second liquid phase pipe 6B which is supplied to the intermediate heat exchanger 2 during the cooling operation.
[0015]
The electric pump 9 of the first liquid phase pipe 6A transports the liquid R-134a, which is radiated and condensed by the outdoor unit 1 to the indoor unit that is mostly installed below the outdoor unit 1 during cooling operation. Therefore, a small pump is used. On the other hand, the electric pump 13 of the second liquid phase pipe 6B is a pump for transporting the liquid R-134a that is radiated and condensed by the indoor unit to the upper outdoor unit 1 during the heating operation . A pump is used.
[0016]
The receiver tank 8, the electric pump 9, the cooling / heating switching valve 10, the on-off valve 15 a, and the on-off valve 15 b are incorporated in the outdoor unit 1. The gas phase section of the receiver tank 8 and the gas phase pipe 7 communicate with each other via a thin pressure equalizing pipe 16 having an on-off valve 15b, and a liquid for detecting the liquid level of R-134a in the heat exchanger 2 is used. A surface sensor 17 is also provided.
[0017]
The outdoor unit 1 also has a function of controlling the amount of input heat so that the temperature of the R-134a that is cooled by the heat exchanger 2 and discharged to the liquid phase pipe 6 during cooling operation is a predetermined temperature, for example, 7 ° C. The indoor unit performs a cooling operation via the heat exchanger 5, and the opening degree of the flow control valve 11 is adjusted so that the temperature of the R-134a discharged to the gas phase pipe 7 rises to a predetermined temperature, for example, 12 ° C. It has a function to adjust.
[0018]
And, explaining the circulation cycle at the time of cooling operation of R-134a enclosed in the closed circuit 3, R-134a is cooled and condensed through the tube wall of the heat exchanger 2 by the cold generated in the outdoor unit 1, The liquid is discharged to the first liquid phase pipe 6A and accumulated in the receiver tank 8, and a part of the electric pump 9 is supplied to the heat exchanger 5 of each indoor unit at a predetermined temperature to perform the cooling operation, and the remaining part Is returned to the heat exchanger 2 via the second liquid phase pipe 6B branched from the lower part of the first liquid phase pipe 6A.
[0019]
That is, a part of the liquid R-134a condensed by releasing heat in the outdoor unit 1 is supplied from the flow rate adjusting valve 11 opened to the heat exchanger 5 of each indoor unit and performs the cooling operation, and the remaining part is always Since the liquid is returned to the heat exchanger 2 via the second liquid phase pipe 6B, the second R-134a is circulated to the indoor unit during partial load operation or the like. The amount of R-134a flowing through the first liquid phase pipe 6A reaching the liquid phase pipe 6B is large, and therefore the influence of the outside air temperature is relatively small, and bubbles are generated in the liquid R-134a in this portion. Few. Moreover, even if bubbles are generated, R-134a is returned to the heat exchanger 2 of the outdoor unit 1 through the second liquid phase pipe 6B and recondensed, so that the bubbles have an adverse effect on the cooling operation. There is nothing.
[0020]
In addition, when the outdoor unit 1 starts cooling at the start of the cooling operation or the like, the pressure in the closed circuit 3 suddenly decreases, and the liquid R-134a bubbles in the liquid phase pipe 6 all at once. Since the circulating force for returning the foamed R-134a to the heat exchanger 2 of the outdoor unit 1 through the second liquid phase pipe 6B is increased by operating the No. 13, the foamed R-134a is quickly replaced by the heat exchanger. It flows into 2 and dissipates and condenses. Thereby, bubbles disappear from the R-134a in the liquid phase tube 6 quickly.
[0021]
Then, when the liquid R-134a bubbles all at once in the liquid phase pipe 6, the electric pump 13 pushes out the volume corresponding to the volume of the bubbles to the outdoor unit 1, and the liquid level in the heat exchanger 2 is increased. When the bubble rises and the bubble disappears, the rise is returned to the liquid phase tube 6 and the liquid level is lowered. Therefore, when the liquid level sensor 17 detects a liquid level higher than the first predetermined level, the first level is activated. Control is performed as shown in FIG. 2, for example, so as to stop when a liquid level lower than a second predetermined level lower than the predetermined level is detected.
[0022]
That is, first, the liquid level of the R-134a is detected by the liquid level sensor 17 (step S1), and then it is determined whether or not the liquid level is higher than the first predetermined level (step S2). Is determined (step S3). When the flag is not set, the flag is set (step S4), the electric pump 13 is activated (step S5), and the process returns to step S1. Moreover, it returns to step S1 also when it determines with the flag standing in step S3.
[0023]
On the other hand, when it is determined in step S2 that the liquid level is not higher than the first predetermined level, the process proceeds to step S6 to determine whether or not the liquid level is lower than the second predetermined level. (Step S7), when the flag is set, the flag is turned off (step S8), the electric pump 13 is stopped (step S9), and the process returns to step S1. Also, when it is determined in step S6 that the liquid level is not lower than the second predetermined level and when it is determined in step S7 that the flag is not raised, the process returns to step S1.
[0024]
In addition, it cools by depriving heat from the high-temperature indoor air that flows into the indoor unit through the flow control valve 11 and is forcibly conveyed by the blower through the tube wall of the heat exchanger 5, and evaporates. The gas R-134a is cooled, condensed and liquefied, flows into the heat exchanger 2 of the outdoor unit 1 through the gas phase pipe 7, and is again radiated and condensed here. Conventionally known circulation is performed.
[0025]
3 (a) and 3 (b) are schematic views of the evaporator 2 when an evaporator of an absorption refrigeration machine is used for the heat exchanger 2 shown in FIG. 1, and a plurality of heat transfer tubes 22a and 22b are shown in FIG. The gas pipe 7, the second liquid phase pipe 6 </ b> B, and the liquid pipe 20 are connected to each other through spaces 21 a, 21 b, and 21 c formed at both ends.
The evaporated gas returning from the gas phase tube 7 is supplied to the liquid tube 20 through the space 21a, the plurality of heat transfer tubes 22a, the space 21c, the plurality of heat transfer tubes 22b, and the space 21b. At this time, the gas R-134a flowing in the heat transfer tubes 22a and 22b is liquefied by the evaporating action of the refrigerant dropped on the outer peripheral surfaces of the heat transfer tubes 22a and 22b.
Liquids of R-134a which is supplied from the electric pump 13 is supplied to the space 21a.
[0026]
4 (a) and 4 (b) are schematic views showing another embodiment of the heat exchanger 2 shown in FIG. 3, and a plurality of heat transfer tubes 22 are provided through spaces 21a and 21c formed at both ends thereof. The gas phase pipe 7, the second liquid phase pipe 6 </ b > B, and the liquid pipe 20 are connected.
The vaporized gas returning from the gas phase tube 7 is supplied to the liquid tube 20 through the space 21a, the plurality of heat transfer tubes 22, and the space 21c. At this time, the gas R-134a flowing in the heat transfer tube 22 is liquefied by the evaporation of the refrigerant dripped onto the outer peripheral surface of the heat transfer tube 22 .
The liquid R-134a supplied from the electric pump 13 is supplied to the middle of the space 21a as shown.
[0027]
FIG. 5 is a schematic diagram of the heating operation. The operation of the electric pump 9 is stopped, the cooling / heating switching valve 10 and the on-off valves 15a and 15b are closed, and the second temperature is generated while the outdoor unit 1 generates heat. The electric pump 13 of the liquid phase pipe 6B is operated.
[0028]
That is, the R-134a of the closed circuit 3 is heated and evaporated through the tube wall of the heat exchanger 2 due to the heat generated in the outdoor unit 1, and the evaporated R-134a passes through the gas phase tubes 7. It is supplied to the heat exchanger 5 of the indoor unit at a predetermined temperature, for example, 55 ° C., and in each heat exchanger 5, R-134a dissipates heat to the low-temperature indoor air forcibly supplied by the blower to condense / liquefy. However, a heating operation is performed during the condensation and liquefaction. The R-134a liquid condensed in the heat exchanger 5 flows into the receiver tank 12 through the flow rate adjusting valve 11, and this R-134a is supplied to the receiver tank 8 by the conveying force of the electric pump 13. The heat exchanger 2 is returned.
[0029]
That is, the air conditioner of the present invention shown in FIG. 1 and FIG. 5 is configured such that either air conditioning of cooling / heating can be selected and executed. In addition, as an absorption refrigerating machine which can supply cold heat from the heat exchanger 2 piped to the evaporator or can supply warm heat, for example, the one disclosed in JP-A-7-318189 can be used.
[0030]
By the way, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit described in the claims.
[0031]
In addition to the R-134a, the phase changeable refrigerant sealed in the closed circuit 3 includes R-407c, R-404A, R-410c, etc. that easily change phase by controlling temperature and pressure. Also good.
[0032]
【The invention's effect】
As described above, according to the air conditioner of the present invention, the generation of bubbles is suppressed even when the amount of liquid-phase refrigerant circulated and supplied to the indoor unit is small, such as during partial load operation of cooling. Further, even when bubbles are generated, they are returned to the outdoor unit via the second liquid phase tube and recondensed, so that the bubbles do not adversely affect the cooling operation.
[0033]
In particular, when the outdoor unit starts cooling at the start of the cooling operation, the pressure in the circuit suddenly drops, and even when the bubbles in the liquid phase tube all at once, the second liquid pump is operated. Since the circulating force for returning the foamed liquid phase refrigerant to the outdoor unit through the second liquid phase tube is increased, it quickly flows into the outdoor unit and radiates and condenses. Thereby, bubbles can be quickly eliminated from the refrigerant in the liquid phase tube.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an embodiment of the present invention.
FIG. 2 is a flowchart showing a control example of an electric pump provided in a second liquid phase pipe.
FIG. 3 is a schematic diagram of the evaporator shown in FIG. 1;
FIG. 4 is a schematic view showing another embodiment of the evaporator shown in FIG. 1;
FIG. 5 is a schematic view showing a refrigerant flow during heating operation.
FIG. 6 is an explanatory diagram of a conventional technique.
[Explanation of symbols]
1 outdoor unit 2 heat exchanger 3 closed circuit 4 indoor unit 5 heat exchanger 6 liquid phase pipe 6A first liquid phase pipe 6B second liquid phase pipe 7 gas phase pipe 8 receiver tank 9 electric pump 10 cooling / heating switching valve 11 Flow control valve 12 Receiver tank 13 Electric pump 14 Check valve 15a Open / close valve 15b Open / close valve 16 Pressure equalizing pipe 17 Liquid level sensor 18 Blower 20 Liquid pipe 21a Space 21b Space 21c Space

Claims (1)

A refrigerant capable of phase change by connecting between an outdoor unit and a plurality of indoor units, all or a majority of which are installed below the outdoor unit, with a liquid phase pipe having a cooling auxiliary pump and a gas phase pipe. Is circulated in the order of the outdoor unit, the liquid phase pipe, the indoor unit, and the gas phase pipe using the difference in specific gravity between the liquid phase and the gas phase and the discharge force of the cooling auxiliary pump. from the air-conditioning apparatus configured to be capable of cooling operation using a phase change to a gas phase, from the lower portion of the liquid phase pipe leading to the lowermost of the indoor unit relative to the outdoor unit, the second leading to the outdoor unit A liquid phase pipe is provided , and a second liquid pump for transporting the refrigerant to the outdoor unit is provided in the second liquid phase pipe, and the refrigerant condensed and liquefied by the outdoor unit during cooling operation is supplied to the liquid phase pipe. Is supplied to the indoor unit via the second liquid pump, and the second liquid pump is operated to flow to the second liquid phase pipe. Allowed to, the increasing circulation amount of the refrigerant circulating through the liquid phase pipe, the air conditioner, wherein a bubble generated in the liquid phase tube was refluxed configured to be capable of the outdoor unit.

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