JP5639984B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner.

  In order to construct a computer network, a server for communication, a database, a file management, etc. is required to receive and process a request from each computer. This type of server is installed in the server machine room for convenience of operation and management. A plurality of servers are stored in a server rack, and a plurality of server racks are installed in the server machine room. On the other hand, the server generates a large amount of heat during operation, and is operated with an air conditioner for stable operation.

  In data centers and the like having many server machine rooms, in recent years, there has been an increasing demand for reducing power consumption other than for servers, and air conditioners are also required to have low power consumption. As an air conditioner for the entire server machine room, in general, a compressor, an outdoor heat exchanger (condenser), an expansion valve, and an indoor heat exchanger (evaporator) are connected in order by refrigerant piping to form an air conditioner. A device is used. However, since the server machine room is operated at about 30 ° C., if the outside air temperature is lower than that, for example in the case of midwinter, the refrigerant can be directly cooled by the outside air by simply circulating the refrigerant without using the compressor. Therefore, the cooling operation can be performed.

  Regarding this point, for example, Japanese Patent Laid-Open No. 10-82566 (Patent Document 1) states, “With a simple configuration, a small number of refrigerant pipes, and without being restricted by installation conditions (height position) of the indoor / outdoor units, An air-cooled package air conditioner that can improve energy efficiency by ensuring energy-saving operation while ensuring necessary and sufficient cooling capacity throughout the year without causing problems such as increased fan power and water quality management. For this purpose, in the vapor compression cooling circuit in which the refrigerant is circulated by connecting the compressor 21, the condenser 22, the expansion valve 13, and the evaporator 11 with piping, the piping between the condenser 22 and the expansion valve 13 is provided. The refrigerant pump 23 is provided on the outside, and the cooling operation of the compression cycle by the operation of the compressor 21 or the cooling operation of the heat transport cycle by the operation of the refrigerant pump 23 is based on the outside air temperature. There have been described as automatically selected to run. "(See Abstract).

Japanese Patent Laid-Open No. 10-82566

  According to the technology described in Patent Document 1, when the outside air temperature is lower than the room temperature, the refrigerant is circulated by the pump, so that the cooling operation is performed with low power consumption compared to the circulation by the compressor. Is possible. However, this patent document 1 considers the possibility of cavitation occurring due to the accumulation of a large amount of gas refrigerant on the inlet side of the pump when the compressor cycle operation by the compressor is switched to the pump cycle operation by the pump. It has not been.

  In the present invention, when switching from compressor cycle operation to pump cycle operation by a pump, the possibility of cavitation is reduced by preventing gas refrigerant from accumulating on the inlet side of the pump, and stable pump cycle operation is performed. An object of the present invention is to provide an air-conditioning apparatus capable of performing the above.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-described problems. To give an example, a compressor that performs a compressor cycle operation for circulating the refrigerant, a condenser that condenses the refrigerant compressed by the compressor, A blower that blows air to the condenser, an expansion valve that expands the refrigerant condensed by the condenser, an evaporator that evaporates the refrigerant expanded by the expansion valve, and liquid refrigerant that flows from the condenser with the compressor stopped A pump that performs a pump cycle operation that circulates a refrigerant by being sent to an expansion valve, and controls the air blower to stop or to be lower than a set speed when shifting from the compressor cycle operation to the pump cycle operation. It is characterized by that.

According to the present invention, when switching from a compressor cycle operation to a pump cycle operation by a pump, the risk of cavitation is reduced by preventing gas refrigerant from accumulating on the inlet side of the pump, and stable pump cycle operation is achieved. It can be carried out.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

The figure for demonstrating the air conditioning apparatus cycle of Example 1. FIG. The figure for demonstrating the air conditioning apparatus cycle of Example 2. FIG. The figure which has arrange | positioned the restrictor 22 instead of the stop valve 21 of FIG. The figure for demonstrating the air conditioning apparatus cycle of Example 3. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

A first embodiment of the present invention will be described.
The air conditioner of the present embodiment has a particularly advantageous effect for cooling operation of a server machine room or the like, and the server machine room to be cooled is about 30 ° C. even when the outside air temperature is low such as in midwinter. It is operated by. Thus, if the outside air temperature is lower than the temperature in the server machine room, cooling can be performed by simply circulating the refrigerant, so that the cooling operation can be performed with low power consumption without using a compressor. Such a system that uses the cold heat of low-temperature outside air is called free cooling. In order to effectively perform free cooling, a system with a forced refrigerant circulation system is being developed. By using a pump for forced circulation, cooling operation with low power consumption can be achieved for a refrigeration cycle using a compressor. Is possible.

  In addition, as equipment attached to the air conditioner, the temperature difference between the air that passes through the air conditioner and the cooling coil is increased by providing a cooling coil that cools the air by passing the cooling water from the refrigerator. And there exists a method corresponding to the low power consumption of an air conditioning apparatus main body. However, this method has a problem in that the structure becomes complicated and the introduction cost increases when viewed as a whole air conditioning system.

Therefore, in the present embodiment, a highly reliable air conditioner will be described in which the cooling coil is provided in series as described above and the power consumption is reduced by the air conditioner alone without increasing the cost.
FIG. 1 is a diagram illustrating an air conditioner for information communication according to the present embodiment. The air conditioner is a compression cycle operation in which the compressor 1, the condenser 2, the surplus refrigerant regulator 8, the stop valve 4, the expansion valve 5, the evaporator 6, and the accumulator 15 are sequentially connected by a refrigerant pipe to perform a cooling operation. And a pump cycle operation in which the condenser 2, the surplus refrigerant regulator 8, the pump 3 (forced refrigerant circulation pump), the stop valve 4, the expansion valve 5 and the evaporator 6 are connected in order by refrigerant pipes for cooling operation. Do the operation. The condenser 2, the excess refrigerant regulator 8, the expansion valve 5, and the evaporator 6 are shared in both cycles. The outlet side of the evaporator 6 has a temperature sensor 13 for detecting the refrigerant temperature and a pressure sensor 14 for detecting the refrigerant pressure, and detects the refrigerant superheat using the detection values of these sensors. Similarly, a pressure sensor 9 that detects the refrigerant temperature and a temperature sensor 10 that detects the refrigerant temperature are also provided on the upstream side of the pump 3, and the supercooling degree of the refrigerant is calculated using the detection values of these sensors.

  The compressor cycle operation and the pump cycle operation are switched depending on the indoor heat load and the outside air condition. The air conditioner of this embodiment is composed of an indoor unit and an outdoor unit, and the indoor unit includes a compressor 1, a stop valve 4, an expansion valve 5, an evaporator 6, an accumulator 15, a temperature sensor 13, a pressure sensor 14, Further, an indoor blower 17 is provided. On the other hand, the outdoor unit includes a condenser 2, a surplus refrigerant regulator 8, a pressure sensor 9, a temperature sensor 10, a pump 3, and an outdoor blower 7.

  Before the pump cycle operation is performed, the degree of supercooling of the refrigerant is calculated from the values of the pressure sensor 9 and the temperature sensor 10, and it is determined whether or not it is in the supercooling region on the ph diagram. When it is not in the supercooling zone, it means that the refrigerant on the inlet side of the pump 3 has two phases. Therefore, when the pump cycle operation is performed in this state, the gas refrigerant flows into the pump inlet side, and the pump There is a possibility that it cannot be circulated. Therefore, in this case, any one of the compressor 1, the outdoor blower 7, and the expansion valve 5 is controlled, an operation for ensuring supercooling for a certain period of time is performed, and the shift to the pump cycle operation is suspended.

  On the other hand, when it is a supercooling region, the shift to the pump cycle operation is permitted and the compressor 1 is stopped. The air conditioner of the present embodiment includes a compressor 1 that performs a compressor cycle operation that circulates a refrigerant, a condenser 2 that condenses the refrigerant compressed by the compressor 1, and a blower (outdoor blower) that blows air to the condenser 2. 7), an expansion valve 5 for expanding the refrigerant condensed by the condenser 2, an evaporator 6 for evaporating the refrigerant expanded by the expansion valve 5, and a liquid flowing from the condenser 2 in a state where the compressor 1 is stopped. A pump 3 that performs a pump cycle operation for circulating the refrigerant by sending the refrigerant to the expansion valve 5, and stops the blower (outdoor blower 7) when shifting from the compressor cycle operation to the pump cycle operation, or Control so that it is below the set speed.

  When the blower (outdoor blower 7) is continuously operated during the transition from the compressor cycle operation to the pump cycle operation, the pressure of the refrigerant on the inlet side of the pump 3 decreases, and the compressor cycle operation is performed on the ph diagram. Even if it is in the supercooling region, there is a risk of becoming a two-phase region. Therefore, in the present embodiment, as described above, the blower (outdoor blower 7) is stopped or controlled so as to be equal to or lower than the set speed to prevent such a pressure from being lowered, and the refrigerant on the inlet side of the pump 3 can be prevented. Is to be in the supercooling region. As a result, a large amount of gas refrigerant does not flow into the pump 3 during the pump cycle operation, so that the liquid refrigerant can be introduced and the pump can be started and operated stably.

  In addition, although it is necessary to perform immediately after stopping the compressor 1 about the control which makes the above-mentioned air blower (outdoor air blower 7) stop, or it becomes below a setting speed (for example, within 200 sec), It may be performed before the compressor 1 is stopped.

  In addition, the air conditioner of the present embodiment further includes an outdoor temperature sensor that detects an outdoor temperature (not shown), and the temperature detected by the outdoor temperature sensor is lower than the set temperature when the compressor cycle operation is shifted to the pump cycle operation. It is advisable to stop the blower (outdoor blower 7) only or to control the speed to be lower than the set speed. That is, particularly when the outside air temperature is low, the refrigerant pressure is reduced due to the operation of the blower (outdoor blower 7). However, when the outside air temperature is high, the refrigerant pressure is hardly lowered. The set temperature is preferably set to about 5 ° C., for example.

  Furthermore, it is desirable to reduce or close the opening of the expansion valve 5 when shifting from the compressor cycle operation to the pump cycle operation. When shifting to the pump cycle operation, if the opening of the expansion valve 5 is kept open, the refrigerant flows to the indoor unit side (evaporator 6 side). As a result, a large amount of gas refrigerant may flow into the pump 3 during pump operation. In particular, when the outdoor unit is above the indoor unit, the liquid refrigerant easily flows to the lower indoor unit side (evaporator 6 side), and this phenomenon is likely to occur.

  Therefore, since the flow of the refrigerant can be stopped by narrowing or closing the opening of the expansion valve 5 as described above, a shortage of refrigerant in the pump 3 can be prevented, and a large amount of gas refrigerant can flow into the pump 3. I can not. Therefore, the pump cycle operation can be stably performed. Alternatively, when the stop valve 4 that opens and closes the flow path between the pump and the expansion valve is closed instead of the expansion valve 5 when shifting from the compressor cycle operation to the pump cycle operation, the same applies. An effect can be obtained. The timing for closing the expansion valve 5 or the stop valve 4 is preferably immediately after the compressor 1 is stopped, but may be performed immediately before the stop.

  When the blower (outdoor blower 7) as described above is controlled, the pump is started while the stop valve 4 or the expansion valve 5 is opened when the refrigerant on the inlet side of the pump 3 is in the supercooling region. After the pump is started, the pressure gradually decreases from the high pressure state during the compressor cycle operation, but the outdoor blower 7 maintains a low rotational speed and avoids a sudden pressure change until the pressure drop becomes substantially constant. . As a result, the pressure and temperature on the inlet side of the pump 3 can be kept in the supercooling region on the ph diagram, so that the pump cycle operation can be performed stably. From the point in time when the pressure drop at the inlet side of the pump 3 reaches a certain level, the pump operation speed and the outdoor fan are increased stepwise, and normal pump operation corresponding to the load is performed.

  Note that the above-described outdoor blower 7 is opened only when the degree of supercooling is 1 degree or more based on the degree of supercooling obtained from the pressure sensor 9 provided at the inlet of the pump 3 and the temperature sensor 10 provided at the inlet of the pump 3. It is desirable to control the valve 4 or the expansion valve 5.

A second embodiment of the present invention will be described with reference to FIG. About the same code | symbol, since it is the same as that of Example 1, description is abbreviate | omitted.
FIG. 2 differs from FIG. 1 in that a stop valve 21 is provided between the condenser 2 and the surplus refrigerant regulator 8. Also in the present embodiment, as in the first embodiment, when the refrigerant on the inlet side of the pump 3 is in the supercooling region, the operation shifts to the pump cycle operation. At this time, the stop valve 21 is closed. Even when the outdoor fan 7 continues to blow by closing the stop valve 21 when shifting to the pump cycle operation in this way, the refrigerant from the condenser 2 does not flow to the pump 3 side. Even if a pressure drop occurs on the outlet side, it is not affected by this. That is, even if a gas refrigerant is generated due to a pressure drop, the gas refrigerant does not flow to the pump 3, so that cavitation can be prevented and stable pump activation and pump cycle operation can be performed.

  The timing for closing the stop valve 21 is preferably immediately after the compressor 1 is stopped, but may be closed immediately before the stop. After the start-up preparation of the pump 3 is completed, the stop valve 21 and the stop valve 4 are opened, and the pump is started while the expansion valve 5 is opened. After starting the pump, the pressure gradually decreases from the high pressure state during the compression cycle, but until the pressure drop becomes almost constant, the outdoor blower 7 maintains a low rotation speed and avoids a sudden change in pressure. The inlet pressure and temperature are kept in the supercooling region on the ph diagram.

  FIG. 3 is obtained by replacing the stop valve 21 of FIG. Although the above-described stop valve 21 could only be opened and closed, the same effect can be obtained by reducing the opening of the restrictor 22 when shifting to the pump cycle operation. In addition, although control of the stop valve 21 and the restrictor 22 has been described in the present embodiment, it is needless to say that the control of the first embodiment is preferably performed in addition to the control of the present embodiment.

Example 3 will be described with reference to FIG.
FIG. 4 shows a cycle system in which a supercooler 25 is provided between the surplus refrigerant regulator 8 and the pump 3 (forced refrigerant circulation pump) in addition to FIG. The same symbols as those in FIG. 2 mean the same configuration, and thus the description thereof is omitted. Further, a stop valve 23 is provided between the surplus refrigerant regulator 8 and the supercooler 25.

  The stop valve 21 and the stop valve 23 are configured to be closed only when energized, and are configured to be automatically opened during a power failure. Thus, it can be closed only when control is required, and is automatically opened at the time of a power failure, so that an abnormal pressure increase due to liquid sealing of the surplus refrigerant device can be avoided during no control. In addition, a pressure sensor 24 is provided between the stop valve 21 and the stop valve 23, and when the detected value of the pressure sensor 24 is equal to or greater than a certain value, control is performed to open the stop valve 21 and the stop valve 23. .

  As in the first and second embodiments, when the refrigerant on the inlet side of the pump 3 is in the supercooling region, the operation shifts to the pump cycle operation. That is, the compressor 1 is stopped, and the stop valve 21 and the stop valve 23 are further closed. When the compressor 1 is stopped, the expansion valve 5 is fully closed or the stop valve 4 is closed. After the pump 3 is ready for starting, the stop valve 21, the stop valve 23, and the stop valve 4 are opened, and the pump is started while the expansion valve 5 is opened. After starting the pump, the pressure gradually decreases from the high pressure state during the compression cycle, but until the pressure drop becomes almost constant, the outdoor blower 7 maintains a low rotation speed and avoids a sudden change in pressure. The inlet pressure and temperature are kept in the supercooling region on the ph diagram. Needless to say, it is desirable to perform the control of the first or second embodiment in addition to the control of the present embodiment.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Pump 4, 21, 23 Stop valve 5 Expansion valve 6 Evaporator 7 Outdoor blower 8 Excess refrigerant adjusting device 9 Pump inlet pressure sensor 10 Pump inlet temperature sensor 11 Silencer 12 Compressor outlet valve 13 Evaporator Outlet temperature sensors 14 and 24 Pressure sensor 15 Accumulator 16 Compressor outlet pressure sensor 17 Indoor blower 18 Pump replacement stop valve 19 Pump bypass valve 20 Compressor bypass valve 22 Throttler 25 Supercooler

Claims (11)

A compressor that performs a compressor cycle operation for circulating the refrigerant;
A condenser for condensing the refrigerant compressed by the compressor;
A blower for blowing air to the condenser;
An expansion valve for expanding the refrigerant condensed by the condenser;
An evaporator for evaporating the refrigerant expanded by the expansion valve;
A pump that performs a pump cycle operation for circulating the refrigerant by sending liquid refrigerant flowing from the condenser to the expansion valve in a state where the compressor is stopped, and
The air conditioner is controlled so as to stop the blower or to be equal to or less than a set speed when shifting from the compressor cycle operation to the pump cycle operation. In the air conditioning apparatus according to claim 1,
An air conditioner that throttles or closes the opening of the expansion valve when shifting from the compressor cycle operation to the pump cycle operation. In the air conditioning apparatus according to claim 1,
Further comprising a stop valve for opening and closing a flow path between the pump and the expansion valve;
From said compressor cycle operation when moving the pump cycle operation, air conditioner, characterized in that closing said open valve. In the air conditioning apparatus according to claim 1,
It further includes an outdoor temperature sensor for detecting the outdoor temperature,
When shifting from the compressor cycle operation to the pump cycle operation, the blower is stopped only when the temperature detected by the outdoor temperature sensor is equal to or lower than a set temperature, or controlled to be equal to or lower than a set speed. An air conditioner characterized. In the air conditioning apparatus according to claim 1,
Further comprising a stop valve for opening and closing a flow path between the pump and the condenser;
An air conditioner that closes the stop valve when shifting from the compressor cycle operation to the pump cycle operation. In the air conditioning apparatus according to claim 5,
A tank for storing excess refrigerant on the inlet side of the pump;
The air conditioner characterized in that the stop valve closes a flow path between the tank and the condenser. In the air conditioning apparatus according to claim 5 or 6,
An air conditioner that throttles or closes the opening of the expansion valve when shifting from the compressor cycle operation to the pump cycle operation. In the air conditioning apparatus according to claim 5 or 6,
Further comprising a stop valve for opening and closing a flow path between the pump and the expansion valve;
From said compressor cycle operation when moving the pump cycle operation, air conditioner, characterized in that closing said open valve. In the air conditioning apparatus according to claim 5 or 6,
It further includes an outdoor temperature sensor for detecting the outdoor temperature,
An air conditioner that closes the stop valve only when the temperature detected by the outdoor temperature sensor is equal to or lower than a preset temperature when the compressor cycle operation is shifted to the pump cycle operation. In the air conditioning apparatus according to claim 1,
Further comprising a restrictor for reducing the size of the flow path between the pump and the condenser;
An air conditioner that reduces the opening of the throttle when the compressor cycle operation is shifted to the pump cycle operation. The air conditioner according to claim 10,
A tank for storing excess refrigerant on the inlet side of the pump;
Further comprising a stop valve for opening and closing the flow path between the tank and the evaporator;
An air conditioner that closes the stop valve when shifting from the compressor cycle operation to the pump cycle operation.