JP4431829B2 - Air conditioner - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention relates to improving the performance of both the air-conditioning apparatus during cooling operation and heating operation, and is particularly suitable for improving efficiency regardless of the length of the connecting pipe between the outdoor unit and the indoor unit. .

  In recent years, a refrigeration cycle apparatus using carbon dioxide as a refrigerant, which has an ozone depletion coefficient of zero and a global warming coefficient much smaller than that of fluorocarbons, has attracted attention. The carbon dioxide refrigerant has a critical temperature as low as 31.06 ° C., and when a temperature higher than this temperature is used, the carbon dioxide refrigerant is used on the high pressure side (compressor outlet to radiator to decompressor inlet) of the refrigeration cycle apparatus. This is a supercritical state where no condensation occurs, and the operation efficiency of the refrigeration cycle apparatus is lower than that of conventional chlorofluorocarbon refrigerants. For this reason, in order to improve the operating efficiency of the refrigeration cycle in the supercritical state, an expander is provided as a decompression device for the refrigeration cycle, and the expansion power recovered by the expander is used as part of the compressor driving force. Various methods have been proposed, and a method of providing a sub-compressor driven by expansion power recovered by an expander at a position where two-stage compression is performed.

  For example, driven by the suction side of the sub compressor driven by the expansion power of the expander and the motor (motor) in order to keep the discharge side pressure of the compressor driven by the motor (motor) low and reduce the input of the motor The discharge side of the compressor is connected in series in the refrigerant circuit so as to perform two-stage compression of the refrigerant, and is driven by the expansion power of the compressor and the expander driven by an electric motor (motor) The refrigerant compressed by the sub-compressor is cooled by the gas cooler and recovers the expansion power when the high-pressure refrigerant gas is decompressed by the expander, and this recovered power is transmitted to the sub-compressor via the shaft. The refrigerant after decompression is configured by a refrigerant circuit that is heated by an evaporator and returns to the suction side of a compressor driven by an electric motor (motor) via an accumulator that stores excess liquid refrigerant. Sentence It has been described in 1.

  Moreover, in order to reduce the difference in density ratio due to the refrigerant flow (operation mode) and improve the efficiency of power recovery in the expander designed as a fixed density ratio, the refrigerant flow using an indoor heat exchanger as an evaporator In this case, the discharge side of the sub-compressor is set to the suction side of the compressor, and the refrigerant sucked into the compressor by the sub-compressor is supplied (charged), and the indoor heat exchanger is dissipated. In the case of the refrigerant flow used as a compressor, the refrigeration cycle apparatus is configured so that the discharge side of the compressor becomes the suction side of the sub-compressor and the refrigerant discharged from the compressor is further pressurized (expressor). This is described in Patent Document 2.

JP 2003-279179 A (FIG. 2) JP 2004-138332 A (FIG. 1)

  When the above prior art is applied to an air conditioner, the pipe connecting the outdoor unit and the indoor unit in which the expander is installed becomes a large pressure reducing device. Also, when installing a large number of indoor units, the load of each indoor unit is different, so that the pressure reducing device provides resistance to the flow of refrigerant and adjusts the amount of flowing refrigerant. When is used, the differential pressure in the expander cannot be secured, and the power recovery becomes insufficient.

  An object of the present invention is to solve the above-described conventional technical problems and maximize the power recovery effect in the expander without being affected by the connecting pipe, the decompression device in each indoor unit, and the like.

In order to achieve the above object, the present invention provides a main compressor driven by an electric motor, a four-way valve, an outdoor heat exchanger, an outdoor pressure reducing device, a liquid receiver, an indoor pressure reducing device, and an indoor heat exchanger. In the harmony device, a bridge circuit including a check valve for making the refrigerant flow in the liquid receiver in one direction, an expander provided on the outlet side of the liquid receiver, and expansion recovered by the expander A sub-compressor driven by power and having a discharge side connected to the suction side of the main compressor, a heat exchanger having a main flow part connected to the outlet side of the liquid receiver, and further provided with a sub-flow part; A part of the liquid refrigerant is depressurized by a decompression device at the downstream portion of the receiver, exchanges heat with the refrigerant that passes through the main flow portion, is guided to the subflow portion, and passes through the subflow portion. Is sucked into the sub compressor through the expander .

  Furthermore, in the above, the positions of the main compressor and the sub compressor may be exchanged, and the sub compressor may be connected to the discharge side of the main compressor.

  Furthermore, in the above, it is desirable that the refrigerant is a CO2 refrigerant.

According to the present invention can be carried out under reduced pressure by the connection piping between the outdoor unit and the indoor unit without being affected by the reduced pressure due distribution of indoor refrigerant, the recovery of power in the expander.

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

FIG. 1 shows Reference Example 1 of the present invention, and FIG. 2 shows the configuration of a refrigeration cycle that does not perform the power recovery shown.
In FIG. 2, 10a is a compressor driven by an electric motor, 20 is a four-way valve for switching between cooling and heating, 30 is an outdoor heat exchanger, 40 is an outdoor pressure reducing device, 50 is a liquid receiver, and 500 is a refrigerant of the liquid receiver. Bridge circuit with a check valve for making the flow of air in the same direction by cooling and heating, 80 is an indoor pressure reducing device, 90 is an indoor heat exchanger, 70a and 70b are connection pipes connecting the indoor unit and the outdoor unit, Reference numerals 60a and 60b denote blocking valves that connect the connecting pipe and the outdoor unit.
During cooling, the refrigerant flows as indicated by the solid line arrow in the figure, and during heating, the four-way valve 20 is switched to become the flow indicated by the broken line arrow to perform air conditioning. In FIG. 1, a heat exchanger 81 for exchanging heat between the expander 100, the sub compressor 10b, and the refrigerant is added to the cycle shown in FIG. 2 as a base. The flow up to the liquid receiver is the same as the cycle of FIG. After adiabatic expansion in the expander 100, the refrigerant becomes a low-pressure and low-temperature refrigerant, and the remaining 80% of the refrigerant is cooled in the heat exchanger 81. The refrigerant itself evaporates, and the indoor heat exchanger 90 during cooling and the outdoor heat exchanger 30 during heating. It is mixed with the refrigerant returning from and sucked into the sub compressor 10b.
Since the sub-compressor 10b is connected to the expander 100 by the shaft 200 and driven by the power generated by the expander 100, no new driving force is required. Since the refrigerant whose pressure has been raised to some extent by the sub-compressor 10b is sucked into the main compressor 10a and compressed, the driving force of the compressor 10a is reduced.

  The reduction in capacity due to the extraction of a part of the refrigerant causes the heat exchanger 81 to recover the cold heat, so that the heat quantity is not lost and the flow rate of the refrigerant flowing to the low pressure side can be reduced. Loss can be reduced. The feature of this cycle is that the power recovery is performed not by the refrigerant main circuit but by a partly extracted refrigerant, so that the refrigerant in the main circuit is not depressurized, and the amount of pressure reduction due to the length and diameter of the connection pipes 70a and 70b. Power recovery can be performed without depending on.

Further, when there are a plurality of indoor units, there is no expander 100 in the main circuit even if the decompression amount of the decompression device 80 is adjusted according to the load of each indoor unit and the distribution ratio of the refrigerant flow is changed. since the connection pipe does not cause a differential pressure foot without being affected by the pressure reducing device, Ru can have enough power recovery.

FIG. 3 shows Reference Example 2 of the present invention. 1 is that the refrigerant guided to the expander 100 is mixed to the discharge side of the sub compressor 10b. As a result, the amount of refrigerant compressed by the sub-compressor 10b is only the refrigerant in the main circuit, so the amount of refrigerant is small, the amount of pressure increase is the same with the same driving force, and the amount of pressure increase in the main compressor 10a is small. It requires, and further can be done power reduction, Ru it is possible to increase the energy-saving effect.

FIG. 4 shows Embodiment 1 of the present invention. The difference from FIG. 1 is that the refrigerant guided to the expander 100 is slightly decompressed by the decompression device 110 and becomes low temperature, evaporates in the heat exchanger 81, and is superheated steam. Then, adiabatic expansion is performed by the expander 100. Thereby, in the first and second embodiments, the expander expanded the two-phase flow, whereas in the present embodiment, the steam is reliably expanded. In other words, the power recovery by the expander is less recovered when the state is liquefied due to the characteristics of the refrigerant, even if the differential pressure is the same, and the recovered amount increases as the vaporization rate increases or the ratio of the amount of vapor increases or superheated steam Therefore, the effect of power recovery is further increased.

As mentioned above, in embodiment shown in Example 1, although it was set as the structure of the main compressor after the subcompressor, it is good also as the contrary. In this case, since the density increases as the pressure is higher than the physical properties of the refrigerant, there is an advantage that the sub compressor can be made compact. Furthermore, the type of refrigerant is preferably a refrigerant with a large amount of recovered power, such as a CO2 refrigerant, and the performance improvement effect is increased. Further, the electric motor that drives the main compressor may be engine driven by fuel.

The refrigeration cycle system | strain diagram of the air conditioning apparatus which shows the reference example 1 of this invention. The refrigerating cycle system diagram of the air conditioning apparatus used as a base. The refrigeration cycle system | strain diagram of the air conditioning apparatus which shows the reference example 2 of this invention. The refrigeration cycle system | strain diagram of the air conditioning apparatus which shows Example 1 of this invention.

  DESCRIPTION OF SYMBOLS 10a ... Main compressor, 20 ... Four-way valve, 30 ... Outdoor heat exchanger, 40 ... Outdoor decompression device, 50 ... Receiver, 60a, 60b ... Blocking valve, 70a, 70b ... Connection piping, 80 ... Indoor expansion valve, DESCRIPTION OF SYMBOLS 90 ... Indoor heat exchanger, 500 ... Check valve, 100 ... Expander, 10b ... Subcompressor, 81 ... Refrigerant heat exchanger, 200 ... Power recovery shaft, 110 ... Decompression device.

Claims (3)

In an air conditioner in which a main compressor driven by an electric motor, a four-way valve, an outdoor heat exchanger, an outdoor pressure reducing device, a liquid receiver, an indoor pressure reducing device, and an indoor heat exchanger are connected in order,
A bridge circuit with a check valve for unidirectional flow of refrigerant in the receiver;
An expander provided on the outlet side of the receiver;
A sub-compressor driven by expansion power recovered by the expander and having a discharge side connected to a suction side of the main compressor;
A heat exchanger in which a main flow part is connected to an outlet side of the liquid receiver and a sub flow part is further provided, and
A part of the liquid refrigerant is decompressed by a decompression device at the downstream portion of the receiver, and is exchanged with the refrigerant that is guided to the secondary flow portion and passes through the main flow portion, and the refrigerant that has passed through the secondary flow portion is expanded. An air conditioner that is sucked into the sub-compressor through a compressor. 2. The air conditioner according to claim 1, wherein positions of the main compressor and the sub compressor are exchanged, and the sub compressor is connected to a discharge side of the main compressor . 2. An air conditioner according to claim 1, wherein the refrigerant is a CO2 refrigerant .

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