JP2010112657A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner that does not use a complicated bridge circuit, uses a dryer of a one-way flow specification, and in which a liquid coolant is supplied to the dryer during both cooling and heating operations. <P>SOLUTION: This air conditioner 1 performs cooling operation or heating operation by circulating a CO2 coolant, and includes a bypass 60 for communicating a high pressure side coolant pipe to a low pressure side coolant pipe via the dryer 62. Even when the cooling operation and the heating operation are switched, the passing direction of the coolant through the dryer 62 is not changed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an air conditioner that uses a CO 2 refrigerant and performs indoor air conditioning by vapor compression refrigeration cycle operation.

  In an air conditioner that requires local piping work, moisture may be excessively mixed into the piping during installation, and if a refrigerant with a low saturated moisture concentration (for example, CO2 refrigerant) is used, the moisture freezes. The piping may be blocked. For this reason, a method for adsorbing moisture by connecting a dryer to the refrigerant circuit has been proposed (see Patent Document 1). In the invention according to Patent Document 1, the refrigerant is allowed to flow through a bypass connected to the dryer every predetermined time every day so that the liquid refrigerant is supplied to the dryer during both the cooling operation and the heating operation. Returning to the circuit.

If a dryer with a bidirectional flow specification is adopted, it is not necessary to perform complicated control as in the invention according to Patent Document 1, but it becomes a high-pressure bidirectional flow specification dryer suitable for CO2 refrigerant. Cost increases. Also, by combining a dryer with a one-way flow specification and a bridge circuit, liquid refrigerant is supplied to the dryer during both cooling operation and heating operation, but the refrigerant circuit becomes complicated and the cost increases.
Japanese Patent Laid-Open No. 2001-141341

  An object of the present invention is to provide an air conditioner in which liquid refrigerant is supplied to a dryer during cooling operation and heating operation using a one-way flow specification dryer without using a complicated bridge circuit. is there.

  An air conditioner according to a first aspect of the present invention is an air conditioner that performs a cooling operation or a heating operation by circulating a CO2 refrigerant in the order of a compressor, a condenser, a decompressor, and an evaporator. A bypass is provided that communicates with the low-pressure refrigerant piping through a dryer. The high-pressure side refrigerant pipe communicates the condenser and the decompressor. The low-pressure side refrigerant pipe communicates the compressor and the evaporator.

  In this air conditioner, even if the cooling operation and the heating operation are switched, the direction in which the refrigerant passes through the dryer does not change. As a result, a dryer with a one-way flow specification is adopted as the dryer, which reduces costs.

  An air conditioner according to a second aspect of the present invention is the air conditioner according to the first aspect of the present invention, further comprising a supercooling heat exchanger connected between the condenser and the decompressor. The bypass branches off from a position on the downstream side of the supercooling heat exchanger during the cooling operation.

  In this air conditioner, during the cooling operation, the CO2 refrigerant is supercooled by the supercooling heat exchanger, and a part thereof enters the dryer. Since the CO2 refrigerant passing through the dryer is in liquid form, the core of the dryer due to the two-phase refrigerant inflow is prevented. Furthermore, since the CO2 refrigerant whose temperature has been lowered by the supercooling heat exchanger passes through the dryer, the temperature of the dryer is lowered and the moisture adsorption power of the dryer is improved.

  An air conditioner according to a third aspect of the present invention is the air conditioner according to the second aspect of the present invention, wherein the bypass has a bypass pressure reducing valve that functions as a pressure reducing mechanism on the downstream side of the dryer. The supercooling heat exchanger exchanges heat between the high-pressure CO2 refrigerant that travels from the condenser to the decompressor and the low-pressure CO2 refrigerant that is decompressed by the bypass decompression valve.

  If the dryer is on the downstream side of the bypass pressure reducing valve, the CO2 refrigerant liquefied by the supercooling heat exchanger becomes a two-phase flow and passes through the dryer, thus causing the core of the dryer to be excreted. However, in this air conditioner, the dryer is on the upstream side of the bypass pressure reducing valve, and the CO2 refrigerant passes through the dryer in a liquid state, so that the core of the dryer due to the two-phase refrigerant inflow is prevented.

  An air conditioner according to a fourth aspect is the air conditioner according to the first aspect, further comprising a receiver. The receiver is connected between a bypass point of the bypass and a decompressor that functions at least during heating operation. During the cooling operation, the decompressor depressurizes the CO2 refrigerant from the condenser to the receiver.

  In this air conditioner, if the condensation pressure of the CO2 refrigerant exceeds the critical pressure during the cooling operation, the CO2 refrigerant that has exited the condenser is decompressed by the outdoor expansion valve 35, and the gas component is separated by the receiver. The CO2 refrigerant passing through the dryer becomes liquid and increases in density, and the drying efficiency by the dryer is improved. Further, since the CO2 refrigerant is decompressed by the decompressor, the pressure acting on the dryer is reduced, and the durability of the dryer is improved.

  In the air conditioner according to the first aspect of the present invention, a one-way flow specification dryer is adopted, which reduces costs.

  In the air conditioner according to the second aspect of the present invention, the CO2 refrigerant passing through the dryer is in liquid form, so that the core of the dryer due to the two-phase refrigerant inflow is prevented. Further, the temperature of the dryer is lowered, and the moisture adsorption power of the dryer is improved.

  In the air conditioner according to the third aspect of the invention, the CO2 refrigerant passes through the dryer as a liquid, so that the core of the dryer due to inflow of the two-phase refrigerant is prevented.

  In the air conditioner according to the fourth aspect of the invention, the CO2 refrigerant passing through the dryer becomes liquid and increases in density, and drying efficiency by the dryer is improved. Further, since the CO2 refrigerant is depressurized by the outdoor expansion valve, the pressure acting on the dryer is reduced, and the durability of the dryer is improved.

  Embodiments of the present invention will be described below with reference to the drawings. The following embodiments are specific examples of the present invention and do not limit the technical scope of the present invention.

<Configuration of air conditioner>
FIG. 1 is a schematic configuration diagram of an air-conditioning apparatus according to an embodiment of the present invention. In FIG. 1, an air conditioner 1 mainly includes an outdoor unit 2 as a heat source unit, an indoor unit 4 as a utilization unit connected in parallel thereto, and a control unit 6 that controls the outdoor unit 2 and the indoor unit 4. It has. The refrigerant circuit 10 is configured by connecting the outdoor unit 2, the indoor unit 4, and a refrigerant communication pipe. The refrigerant circulating through the refrigerant circuit 10 is a CO2 refrigerant, and air-conditioning of a room such as a building is performed by vapor compression refrigeration cycle operation.

<Indoor unit>
The indoor unit 4 is installed by being embedded or suspended in a ceiling of a room such as a building or by hanging on a wall surface of the room, and has an indoor expansion valve 41 and an indoor heat exchanger 42. The indoor expansion valve 41 is an electric expansion valve and is connected to the liquid side of the indoor heat exchanger 42. The indoor heat exchanger 42 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and serves as a refrigerant evaporator during cooling operation to cool indoor air. During the heating operation, it becomes a refrigerant condenser and heats indoor air.

<Outdoor unit>
The outdoor unit 2 is installed outside a building or the like, and has a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an outdoor expansion valve 35, a supercooling heat exchanger 36, a receiver 38, and a bypass 60. is doing. The compressor 21 is an inverter compressor whose capacity can be changed by rotational speed control.

  The four-way switching valve 22 is a valve that switches the direction of refrigerant flow. During the cooling operation, the discharge side of the compressor 21 and the gas side of the outdoor heat exchanger 23 are connected, and the gas side of the indoor heat exchanger 42 and the suction side of the compressor 21 are connected (four-way switching in FIG. 1). (See solid line for valve 22). Further, during the heating operation, the discharge side of the compressor 21 and the gas side of the indoor heat exchanger 42 are connected, and the suction side of the compressor 21 and the gas side of the outdoor heat exchanger 23 are connected (four in FIG. 1). (Refer to the broken line of the path switching valve 22).

  The outdoor heat exchanger 23 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins. The outdoor heat exchanger 23 serves as a refrigerant condenser during the cooling operation, and serves as a refrigerant evaporator during the heating operation. It becomes.

  The outdoor expansion valve 35 is an electric expansion valve, and is connected between the outdoor heat exchanger 23 and the indoor expansion valve 41 in order to adjust the pressure, flow rate, and the like of the refrigerant flowing in the refrigerant circuit 10 on the outdoor side. The The supercooling heat exchanger 36 is provided to cool the refrigerant flowing between the outdoor heat exchanger 23 and the indoor expansion valve 41.

  The receiver 38 is connected between the outdoor expansion valve 35 and the supercooling heat exchanger 36, temporarily stores liquid refrigerant, and controls the amount of refrigerant in the outdoor heat exchanger 23 (or the indoor heat exchanger 42). Absorb changes.

  The bypass 60 is provided as a cooling source for the supercooling heat exchanger 36. The bypass 60 branches a part of the refrigerant flowing between the supercooling heat exchanger 36 and the indoor expansion valve 41 and returns it to the suction side of the compressor 21. The bypass 60 is provided with a bypass expansion valve 61 for decompressing the refrigerant. As a result, the refrigerant flowing between the outdoor heat exchanger 23 and the indoor expansion valve 41 is cooled by the refrigerant decompressed by the bypass expansion valve 61 in the supercooling heat exchanger 36. A dryer 62 is provided on the upstream side of the bypass expansion valve 61. The dryer 62 adsorbs moisture from the refrigerant flowing into the bypass 60.

<Operation of air conditioner>
During the cooling operation, the four-way switching valve 22 is in the state shown by the solid line in FIG. 1, the discharge side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23, and the suction side of the compressor 21 is indoor heat exchange. The gas is connected to the gas side of the vessel 42. The degree of opening of the outdoor expansion valve 35 is adjusted so that the refrigerant can be reduced to an intermediate pressure. The intermediate pressure refers to an intermediate value between the high pressure side pressure and the low pressure side pressure in the refrigerant circuit 10.

  When the compressor 21 is started, the high-temperature and high-pressure refrigerant discharged from the compressor 21 is introduced into the outdoor heat exchanger 23 and exchanges heat with outdoor air in the outdoor heat exchanger 23. The refrigerant leaves the outdoor heat exchanger 23 and is reduced to an intermediate pressure by the outdoor expansion valve 35.

  The refrigerant depressurized to the intermediate pressure enters the receiver 38 in a gas-liquid mixed state. In the receiver 38, the liquid refrigerant and the gas refrigerant are separated, and only the liquid refrigerant enters the supercooling heat exchanger 36 and is cooled to become a medium-high temperature intermediate pressure liquid refrigerant. Part of the liquid refrigerant exiting the supercooling heat exchanger 36 branches to the bypass 60 on the way to the indoor expansion valve 41, and the other enters the indoor expansion valve 41.

  The liquid refrigerant branched into the bypass 60 enters the dryer 62 and comes into contact with the adsorption catalyst to remove moisture. This liquid refrigerant is depressurized by the bypass expansion valve 61 and enters the supercooling heat exchanger 36. The liquid refrigerant exchanges heat with the refrigerant coming out of the receiver 38 in the supercooling heat exchanger 36 and evaporates to become a gas refrigerant and is sucked into the compressor 21.

  On the other hand, the liquid refrigerant that has reached the indoor expansion valve 41 is depressurized by the indoor expansion valve 41 and enters the indoor heat exchanger 42 at a low temperature and a low pressure. This refrigerant exchanges heat with indoor air in the indoor heat exchanger 42 to become a gas refrigerant, and is sucked into the compressor 21 again.

  During the heating operation, the four-way switching valve 22 is in the state indicated by the broken line in FIG. 1, the discharge side of the compressor 21 is connected to the gas side of the indoor heat exchanger 42, and the suction side of the compressor 21 is the outdoor heat exchanger 23. The gas side is contacted. The degree of opening of the outdoor expansion valve 35 is adjusted so as to reduce the pressure to a predetermined evaporation pressure. Further, the indoor expansion valve 41 is opened.

  When the compressor 21 is started, the high-temperature and high-pressure refrigerant discharged from the compressor 21 is introduced into the indoor heat exchanger 42 and exchanges heat with indoor air. The refrigerant leaves the indoor heat exchanger 42 and partly branches to the bypass 60, and the other enters the supercooling heat exchanger 36.

  The refrigerant branched to the bypass 60 enters the dryer 62 and comes into contact with the adsorption catalyst to remove moisture. This refrigerant is decompressed by the bypass expansion valve 61 and enters the supercooling heat exchanger 36. Then, this refrigerant exchanges heat with the refrigerant that has not been branched to the bypass 60 by the supercooling heat exchanger 36 and evaporates to become a gas refrigerant and is sucked into the compressor 21.

  On the other hand, the refrigerant that has not branched to the bypass 60 is cooled by the supercooling heat exchanger 36 to be in a gas-liquid mixed state, the liquid refrigerant and the gas refrigerant are separated by the receiver 38, and only the liquid refrigerant goes to the outdoor expansion valve 35. . The liquid refrigerant that has reached the outdoor expansion valve 35 is depressurized by the outdoor expansion valve 35, becomes low temperature / low pressure, and enters the outdoor heat exchanger 23. This refrigerant exchanges heat with outdoor air in the outdoor heat exchanger 23 to become a gas refrigerant, and is sucked into the compressor 21 again.

<Features>
(1)
The air conditioner 1 includes a bypass 60 that connects the high-pressure side refrigerant pipe and the low-pressure side refrigerant pipe via the dryer 62, and the refrigerant passes through the dryer 62 even when the cooling operation and the heating operation are switched. Therefore, the one-way flow specification is adopted as the dryer 62, and the cost is reduced.

(2)
The air conditioner 1 further includes a supercooling heat exchanger 36 connected between the outdoor heat exchanger 23 and the outdoor expansion valve 35, and the bypass 60 is downstream of the supercooling heat exchanger 36 during cooling operation. Branches from the side position. During the cooling operation, the CO 2 refrigerant is supercooled by the supercooling heat exchanger 36, and a part thereof enters the dryer 62. A bypass expansion valve 61 is provided on the downstream side of the dryer 62. Since the CO2 refrigerant passing through the dryer 62 is in a liquid state, the core of the dryer 62 is prevented from being broken due to the two-phase refrigerant inflow. Furthermore, since the CO2 refrigerant whose temperature has been lowered by the supercooling heat exchanger 36 passes through the dryer 62, the temperature of the dryer 62 is lowered, and the moisture adsorbing power of the dryer 62 is improved.

(3)
In the air conditioner 1, the receiver 38 is connected between the branch point of the bypass 60 and the outdoor expansion valve 35 that functions at least during heating operation. During the cooling operation, the outdoor expansion valve 35 depressurizes the CO 2 refrigerant from the outdoor heat exchanger 23 toward the receiver 38. When the high pressure side pressure of the CO2 refrigerant exceeds the critical pressure, the CO2 refrigerant that has exited the outdoor heat exchanger 23 is depressurized by the outdoor expansion valve 35, and the gas component is separated by the receiver 38, so that it passes through the dryer 62. The density of the CO2 refrigerant to be increased increases, and the drying efficiency by the dryer 62 is improved. Moreover, the pressure which acts on the dryer 62 falls and durability of a dryer improves.

  Also, since the CO2 refrigerant in the supercritical state can be a solvent having a high dissolving action, when the CO2 refrigerant in the supercritical state frequently passes through the dryer 62, the adsorbent of the dryer 62 and the support member that supports the adsorbent are adversely affected. There is a possibility of effect. However, in the air conditioning apparatus 1 according to the present embodiment, when the CO2 refrigerant passes through the dryer 62, it is not in a supercritical state, and thus the concern that it adversely affects the adsorbent of the dryer 62 and the support member that supports the adsorbent is eliminated. Is done.

  As described above, according to the present invention, it is useful for an air conditioner in which moisture may be excessively mixed into a pipe during installation.

The schematic block diagram of the air conditioning apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 21 Compressor 23 Outdoor heat exchanger 35 Outdoor expansion valve (decompressor)
36 Supercooler 38 Receiver 41 Indoor expansion valve (pressure reducer)
42 Indoor heat exchanger 60 Bypass 61 Bypass expansion valve (bypass pressure reducer)
62 Dryer

Claims (4)

An air conditioner that performs cooling operation or heating operation by circulating CO2 refrigerant in the order of the compressor (21), the condenser (23, 42), the decompressor (41, 35), and the evaporator (42, 23). There,
A high-pressure side refrigerant pipe connecting the condenser (23, 42) and the decompressor (41, 35), and a low-pressure side refrigerant pipe connecting the compressor (21) and the evaporator (42, 23). With a bypass (60) communicating through a dryer (62),
Air conditioner (1). A supercooling heat exchanger (36) connected between the condenser (23, 42) and the decompressor (41, 35);
The bypass (60) branches off from a position on the downstream side of the supercooling heat exchanger (36) during the cooling operation.
The air conditioner (1) according to claim 1. The bypass (60) has a bypass pressure reducing valve (61) functioning as a pressure reducing mechanism on the downstream side of the dryer (62),
The supercooling heat exchanger (36) includes the high-pressure CO2 refrigerant from the condenser (23, 42) to the decompressor (41, 35) and the low-pressure decompressed by the bypass decompression valve (61). Heat exchange with the CO2 refrigerant;
The air conditioner (1) according to claim 2. A receiver (38) connected between a branch point of the bypass (60) and the pressure reducer (35) that functions at least during the heating operation;
During the cooling operation, the decompressor (35) decompresses the CO2 refrigerant from the condenser (23) toward the receiver (38).
The air conditioner (1) according to claim 1.

Images