JPS5821188B2 - Refrigeration equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a refrigeration system that uses a plurality of capillary tubes as a pressure reducing element, and controls the degree of pressure reduction of a refrigerant in response to load fluctuations on an evaporator, thereby expanding the scope of use of refrigeration operation. The present invention relates to an improved device as described above.

Generally, in refrigeration equipment such as air conditioners and showcases,
As the pressure reducing element, an expansion valve that can dynamically adjust the degree of refrigerant pressure reduction in response to load fluctuations on the evaporator, and a capillary tube that maintains a constant degree of refrigerant pressure reduction are used, but the former is expensive. The latter has its own advantages and disadvantages, including the disadvantage that although it is low in price, it cannot respond to load fluctuations in the evaporator and has a narrow operating range.

For this purpose, as disclosed in Japanese Utility Model Application Publication No. 51-148049, the condensed refrigerant from the condenser is introduced into a flow divider to separate the liquid gas into two layers, and the liquid level is displaced vertically according to the load fluctuation of the evaporator. A system has been proposed that combines the advantages of the expansion valve and the capillary tube described above by sequentially arranging a plurality of capillary tubes in parallel in the direction of displacement. Since multiple capillary tubes facing the displacement section are independently connected, only liquid refrigerant flows into the capillary tubes facing the liquid section, and only liquid refrigerant or gas refrigerant flows through the capillary tubes facing the liquid level displacement section. For this reason, when switching from a normal load state in which liquid refrigerant flows simultaneously to both capillaries to a low-temperature load state in which the liquid level drops and liquid refrigerant flows only in one capillary, the flow rate of liquid refrigerant is controlled by reducing the pressure in the capillary. It had the disadvantage that the evaporation capacity decreased drastically and the evaporation capacity fluctuated rapidly.

In view of the above, the present invention aims to provide a refrigeration system that can continuously change the evaporation capacity by gradually reducing the flow rate of liquid refrigerant using a capillary tube when switching from a normal load state to a low temperature load state. In order to achieve this object, the present invention connects the lower part of a refrigerant container in which liquid refrigerant is always stored and a plurality of parallel capillary tubes with a liquid tube, and connects this branch connection point with the capillary tubes. The liquid level displacement portion of the refrigerant container is connected to at least one capillary tube or in the middle of this capillary tube by a connecting tube.

With this configuration, the liquid refrigerant flows out from the liquid pipe and the connecting pipe, and from a normal load state in which the pressure is controlled by the parallel capillary tubes, to a low-temperature load state in which the liquid level drops to below the liquid level displacement location of the refrigerant container connected to the connecting pipe. At the time of switching, when the liquid level passes through the liquid level displacement point, the refrigerant with a large gas component flows out from the connecting pipe, and the liquid refrigerant flows through the capillary tube connected to this connecting pipe by being supplied from the liquid pipe. As the liquid level drops, the refrigerant with a large amount of gas flows out, and the amount of gas refrigerant gradually increases.The flow rate of liquid refrigerant in the capillary tube connected to the connecting pipe gradually decreases, and finally Since the refrigerant containing only gas components is switched to a low-temperature load state through the connecting pipe, the flow rate of the liquid refrigerant, which is controlled by the reduced pressure flow rate in both capillary tubes, gradually decreases, making it possible to smoothly control the evaporation capacity.

An embodiment of the present invention will be described below based on the drawings. In FIG. 1, 1 is a compressor, 2 is a condenser, 3 is a refrigerant container,
Reference numerals 4 and 5 denote a plurality of parallel capillary tubes (two in one embodiment), 6 an evaporator, and 7 a gas-liquid separator, which are successively connected in a ring to form a refrigeration cycle.

Reference numeral 8 denotes a connecting pipe led out from the liquid level 9a, 9b of the refrigerant container 3, and the outflow end of this pipe is connected to the refrigerant inflow side of one of the capillary tubes 5, so that the liquid gas refrigerant in the refrigerant container 3 is transferred as appropriate. This capillary tube 5 is introduced into the capillary tube 5 as an example.
is set to approximately 1/2 of the decompression resistance of the other capillary tubes 4.

Reference numeral 10 denotes a liquid pipe in which a plurality of parallel capillary tubes 4 and 5 are branched and connected to the lower part of the refrigerant container 3 in which liquid refrigerant is always stored.

Further, the capacity of the refrigerant container 3 is set so that the liquid level 9a is above the connection point of the communication pipe 8 when the evaporator 6 is under a normal load condition.

Therefore, when the evaporator 6 is in a normal load state, the high-humidity, high-pressure refrigerant gas discharged from the compressor 1 is condensed and liquefied in the condenser 2, and then stored in the refrigerant container 3 in a substantially full state. As a result, the liquid refrigerant flows out from the liquid pipe 10 and the communication pipe 8 and is reduced in pressure to a pressure at which it can easily evaporate in a liquid state in both capillary tubes 4.5, and after joining, it is effectively used in the evaporator 6. It is evaporated and vaporized and returned to the compressor 1 via the gas-liquid separator 7.

When the hot water temperature inside the air conditioner or the showcase decreases under such operating conditions, the heat exchange efficiency in the evaporator 6 decreases, and eventually the evaporator 6 becomes frosted, the evaporator 6 does not evaporate sufficiently. The refrigerant is no longer vaporized and flows into the gas-liquid separator 7 as a liquid refrigerant, and the liquid refrigerant is stored in the separator.

That is, the liquid refrigerant stored in the refrigerant container 3 gradually moves to the gas-liquid separator 7 without being completely evaporated, and the amount of liquid refrigerant in the refrigerant container 3 decreases by the amount of transferred refrigerant.
Along with this, the liquid level 9a in the refrigerant container 3 gradually falls and begins to be displaced to the liquid level 9b.

When the liquid surface 9b passes through the connecting point of the connecting pipe 8, the refrigerant containing a large amount of gas flows out from the connecting pipe 8 and mixes with the liquid refrigerant flowing through the capillary tube 5 from the liquid pipe 10. start,
As the liquid level 9b falls, the refrigerant with a large gas component flows out, the amount of gas refrigerant mixed in gradually increases, the flow rate of liquid refrigerant in the capillary tube 5 gradually decreases, and finally the refrigerant with only a gas component flows into the connecting pipe 8. Once the refrigerant passes through the capillary tube 5, only a small amount of the refrigerant stops flowing through the capillary tube 5, and the liquid refrigerant in the liquid tube 10 essentially remains only in the other capillary tube 4, and this capillary has a large resistance to decompression! 4, the refrigerant flow rate is extremely reduced to a minimum amount that can be sufficiently evaporated in the evaporator 6, and the flow of liquid refrigerant into the gas-liquid separator γ is inhibited.

Therefore, operation can be performed down to low temperature load conditions.

As a result of such control, the evaporation pressure increases, and the hot water temperature inside the air conditioner or the showcase also increases, and liquid refrigerant evaporation in the evaporator 6 is promoted, the stored liquid in the gas-liquid separator 7 increases. The refrigerant moves backward to the refrigerant container 3, and the liquid level 9b becomes the liquid level 9.
The load starts to rise to a, and the normal load operating state is restored again.

In this way, the refrigerant is first separated into a liquid gas state in the refrigerant container 3, and the liquid levels 9a, 9 are displaced according to load fluctuations of the evaporator 6.
By reliably leading out the refrigerant in liquid or gaseous form to the communication pipe 8 in state b, the refrigerant flow resistance of one capillary tube 5 is changed, and the flow rate can be automatically controlled to a refrigerant flow rate commensurate with the load of the evaporator 6. Able to drive.

Furthermore, by selecting various pressure reducing resistances of the capillary tubes 4 and 5, the low temperature load operation range can be expanded or reduced.

In addition, in the circuit of the embodiment shown in FIG. 1, a high-pressure liquid refrigerant heat exchanger 11 for antifreezing is interposed in the middle of the liquid pipe 10 as shown in the chain line circuit, and this heat exchanger is connected to the evaporator 6 and the heat exchanger 11. If they are arranged in an exchange relationship so that the high-pressure liquid refrigerant from the refrigerant container 3 passes through the heat exchanger 11 and then is introduced into the capillary tubes 4 and 5, a loaded operating state in which liquid refrigerant is flowing through both capillary tubes 4 and 5 can be achieved. Since both the capillary tubes 4 and 5 are connected in parallel, the combined resistance is small, and a sufficient amount of high-temperature liquid refrigerant passing through the heat exchanger 11 can be secured, so that supercooling can be achieved by this heat exchanger 11.
Moreover, by effectively heating the evaporator 6, especially the lower part, even if the evaporator 6 falls into a somewhat low humidity load state, it can operate extremely efficiently without frost buildup.

Of course, even if the low-temperature load condition is extreme and the gas refrigerant begins to flow out from the connecting pipe 8 as described above, a minimum amount of high-pressure liquid refrigerant is always supplied to the heat exchanger 11 via the liquid pipe 10. Therefore, the pressure in the evaporator 6 can be increased by the heating effect, and the low temperature load operation can be sufficiently coped with.

Also, as shown by the chain line circuit in Figure 1, if the outflow end of the connecting pipe 8 is connected to the middle of the capillary tube 5 instead of to the inflow side, only a small amount of gas refrigerant can be drawn out from the connecting pipe 8 during low load. Therefore, a small diameter tube can provide sufficient functionality.

Next, in the example circuit shown in Fig. 1, if the circuit configuration between point A and point B is changed as shown in Fig. 2 and the capillary tube 5 is replaced with three capillary tubes 5at sb and 5c, the pressure reduction can be selected. Also, the circuit configuration between point A and point B can be changed to the third point.
As shown in the figure, a plurality of capillary tubes 4, 5, 12.degree. 13 are connected in parallel (four in the example).
A communication line 1 is connected between the refrigerant inflow side of 13 (as mentioned above, it may be in the middle of each of these) and the liquid level displacement location of the refrigerant container 3.
8, 14, and 15, the liquid level 9a+sb changes vertically depending on the load condition of the evaporator 6.

Based on the displacements 9c and 9d, the gas refrigerant is appropriately supplied to the capillary tubes 512.
13, allowing for even finer control of the refrigerant flow rate.
Similar to expansion valves, it can be operated over a wide range.

Furthermore, in order to apply the above-described refrigeration system of the present invention to a heat pump type refrigeration and air conditioning system, and perform a wide range heating operation that can cope with low outside temperatures in winter, the circuit configuration shown in FIG. 4 may be used.

That is, a four-way valve 16 for switching between cooling and heating channels is connected between the compressor 1, the discharge side, and the suction side of the gas-liquid separator 7, and the heating condenser 2 is used as an indoor heat exchanger, and the evaporator 6 is used as an indoor heat exchanger. In addition to being used as an external heat exchanger, a parallel circuit of a heating check valve 17 and a cooling capillary tube 18 is connected between the condenser 2 and the refrigerant container 3, and a cooling check valve is connected in parallel to the heating capillary tubes 4 and 5. 19, compressor 1 - four-way valve 16 - condenser 2 - heating check valve 17 - refrigerant container 3 - heating capillary tubes 4 and 5 - evaporator 6 -
A heating cycle is constructed by sequentially circulating refrigerant through the four-way valve 16, gas-liquid separator 7, and compressor 1.

During such a cycle, the flow rate control of the liquid and gas refrigerant passing through the communication pipe 8 and the effective use of the evaporator 6 by the anti-freezing heat exchanger 11 have already been detailed in the above embodiment, so a special explanation will be omitted. If the four-way valve 16 is switched, the evaporator 6 acts as a condenser, the condenser 2 acts as an evaporator, and the refrigerant flows through the cooling check valve 19, the refrigerant container 3, and the cooling capillary tube 18. Cooling operation can be performed.

Furthermore, as another embodiment, as shown in FIG. 5, the outdoor unit 20 and the indoor unit 21 are separated, and the inter-unit piping 2
It is also possible to use it as a separate heat pump type refrigeration system connected at 2.22.

In such a device, the refrigerant container 3 is divided into two large and small containers 3a, 3.
The dog container 63a is built into the indoor unit 21, the small container 3b is built into the outdoor unit 20, and the large container 3a is divided into two parts.
The rising opening end 24 of the pipe 23, which becomes the outflow side during the heating cycle, is provided near the lowest liquid level of 90, which drops during low outside temperatures in winter, and the heating capillary 4 is connected from the lower part of the small container 3b.
, 5, and at the same time, liquid or gas refrigerant is appropriately led out from the upper part of the small container 3b to the communication pipe 8, which is extremely convenient since the number of inter-unit pipes 22a, 22b can be reduced to at least two.

Refrigerant flow control is performed in the large container 3a under normal load conditions during winter heating.
The liquid level 9f is above the opening tip 24, and only the liquid refrigerant is led out from the pipe 23, the small container 3b is filled with the liquid refrigerant, and the liquid refrigerant is led out from the liquid pipe 10 and the connecting pipe 8. A sufficient flow rate of refrigerant commensurate with the load can be supplied to the opening tip 24 located near the liquid level 9e when a low temperature load condition occurs.
By sucking the liquid-gas mixed refrigerant from the refrigerant and separating it into two liquid-gas layers in the small container 3b, and introducing the gas refrigerant into the capillary tube 5, the pressure reduction resistance can be increased and the refrigerant flow rate can be restricted to a value commensurate with the load.

In addition, in this separate type heat pump refrigeration system, the lengths of the inter-unit piping 22a, 22b vary depending on the installation state of the units 20, 210, and if they are extremely long, the pressure loss in the piping 22a becomes too large and flash gas is generated. Therefore, the liquid level 9e and 9f in the large container 3a according to the load
Even if the control is performed, gas components due to the flash gas may be mixed into the small container 3b, and gas refrigerant may flow out from the connecting pipe 8 even under normal load conditions, which may unnecessarily restrict the refrigerant flow rate. There is.

Therefore, in order to compensate for the pressure loss in the pipe 22a and prevent flash gas from being generated, the indoor unit 22
A supercooling coil 25 is disposed before the connection of the pipe 22a inside, or a subcooling coil 25 is disposed before the connection of the pipe 22a in the outdoor unit 20, as shown in the chain line circuit, to prevent flash generated in the pipe 22a. It is preferable to liquefy the gas.

Also, at this time, the liquid level 9 of the large container 3a
If the connecting pipe 81 is taken out from the midpoint of the ey 9f displacement, a general-purpose liquid receiver can be used as a large container.

The flow of refrigerant during heating and cooling is the same as that shown in FIG. 4, so a detailed explanation will be omitted, and the same parts in FIGS. 2 to 6 are denoted by the same reference numerals.

In addition, since the refrigerant container 3 is a two-layer liquid-gas separator, it also serves as a refrigerant storage container, so in small air conditioners with a small amount of refrigerant circulation, a separate refrigerant storage such as a liquid receiver is required. If there is no need to install a gas-liquid separator 7, and if the amount of liquid refrigerant that cannot be completely evaporated by the evaporator 6 is small and there is no risk of liquid compression, the gas-liquid separator 7
You can omit it.

As described above, the present invention provides a refrigeration cycle in which a compressor, a condenser, a plurality of refrigerant containers, a plurality of parallel capillary tubes, and an evaporator are successively connected in an annular manner. The lower part of the container and the plurality of parallel capillary tubes are branched and connected by a liquid tube, and a liquid level displacement point of the refrigerant container is connected to a connecting tube between the branch connection point and at least one of the capillary tubes or in the middle of the capillary tube. Since the liquid refrigerant flows out from the liquid pipe and the connecting pipe, the pressure is controlled to be reduced by the parallel capillary tubes.From the normal load condition, the liquid level drops to below the liquid level displacement point of the refrigerant container connected to the connecting pipe, and one capillary When switching to a low-humidity load state in which the liquid refrigerant is controlled to be substantially decompressed, the amount of liquid refrigerant flowing through the other capillary tube gradually decreases due to the increase in the amount of gas components flowing out from the connecting pipe, and eventually reaches approximately zero. It is possible to continuously change the flow rate to a low temperature load state, and it is possible to smoothly control the evaporation capacity.

In addition, multiple capillary tubes are connected in parallel to reduce the combined decompression resistance and to ensure a sufficient flow rate of liquid refrigerant in the liquid tube led out from the refrigerant container, a high-pressure liquid refrigerant heat exchanger is interposed in the middle of the liquid tube. If the evaporator is placed in a heat exchange relationship with the evaporator to prevent supercooling, the evaporator can be used extremely effectively to prevent freezing.

Moreover, if the refrigerant container and multiple parallel capillary tubes are combined into one set, it can be connected in place of the pressure reducing element in the conventional circuit, providing excellent versatility. It is extremely beneficial, such as being able to perform favorable flow rate control that takes advantage of these advantages.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram showing one embodiment of the device of the present invention;
Figures 3 and 3 are main refrigerant circuit diagrams showing other embodiments that are different from each other, Figures 4 and 5 are refrigerant circuit diagrams that are similar to other embodiments that are different from each other, and Figure 6 is a diagram that shows other embodiments that are different from the one shown in Figure 5. It is a principal part refrigerant circuit diagram showing an example. 1... Compressor, 2... Condenser, 3...
... Refrigerant container, 4.5, 12.13 ... Capillary tube, 6 ... Evaporator, 8 ... Communication pipe,
9...Liquid level, 10...Liquid pipe, 11...
...High pressure liquid refrigerant heat exchanger.

Claims (1)

[Claims] 1. In a refrigeration cycle constructed by sequentially connecting a compressor, a condenser, a refrigerant container, a plurality of parallel capillary tubes, and an evaporator in an annular manner, the lower part of the refrigerant container in which liquid refrigerant is always stored and the plurality of The parallel capillary tubes are branched and connected by a liquid tube, and the liquid level displacement point of the refrigerant container is connected between this branch connection point and at least one of the capillary tubes or in the middle of this capillary tube by a connecting tube. Characteristic refrigeration equipment.