JPWO2012114451A1 - Air conditioner, operation control method of air conditioner, and cooling system - Google Patents

Abstract

Provided are an air conditioner, an operation control method for an air conditioner, and a cooling system capable of stably and quickly starting activation of natural circulation in a natural circulation cycle. A forced circulation cycle for circulating refrigerant between the compressor (11), the first heat exchanger (13), the expansion valve (15), and the second heat exchanger (17); and a bypass pipe (21a) And an air conditioner that can be operated by switching between a natural circulation cycle that circulates refrigerant by density difference among the first heat exchanger (13), the expansion valve (15), and the second heat exchanger (17). In the apparatus (S), when the natural circulation cycle is started, the flow rate of the use-side second heat transfer medium flowing into the second heat exchanger (17) is increased from a predetermined flow rate. [Selection] Figure 1

Description

  The present invention relates to an air conditioner, an operation control method for the air conditioner, and a cooling system, and more particularly, to an air conditioner that performs natural circulation for circulating a refrigerant due to a difference in refrigerant density, an operation control method for the air conditioner, and a cooling system. .

  The air conditioner has a refrigeration cycle, and in a forced circulation cycle in which the refrigerant is circulated by the compressor, the refrigerant is driven by the compressor, flows into the condenser to be condensed and liquefied, decompressed by the expansion valve, The gas-liquid two-phase refrigerant flows into the evaporator and evaporates and cools.

  Further, a natural circulation combined type air conditioner capable of a natural circulation cycle in which the refrigerant is naturally circulated by the density difference of the refrigerant is known (for example, see Patent Document 1). In the natural circulation cycle, the refrigerant is driven by the density difference between the refrigerant liquid and the refrigerant gas, and the circulation amount of the refrigerant is affected by the height of the liquid column due to the refrigerant liquid formed on the evaporator inlet side. In addition, in order for an air conditioner that performs a natural circulation cycle to start heat exchange (that is, to activate the natural circulation cycle), the influence of the indoor temperature, the outdoor temperature, and the refrigerant temperature in the natural circulation cycle is affected. receive. Therefore, when the temperature of the refrigerant in the natural circulation cycle is out of the proper range, the refrigerant liquid is not supplied to the evaporator, resulting in a lack of cooling operation capability or a delay in start-up due to lack of refrigerant. For example, Patent Document 1 is known as a technique for improving the refrigerant shortage during the cooling operation by the refrigerant natural circulation cycle.

Japanese Patent Laid-Open No. 11-257767

  The cooling operation by the natural circulation cycle is generally performed in an intermediate period (time when the outside air temperature is lower than the room temperature). In order for the operation by the natural circulation cycle to be performed, a certain temperature difference (for example, about ΔT = 5 ° C.) is usually required between the indoor temperature and the outdoor temperature. It becomes impossible to completely liquefy the gas refrigerant flowing in. When the outdoor temperature is low, the refrigerant in the refrigerant circuit stored in the outdoor unit is kept at a pressure balanced with the outdoor temperature. For this reason, in order to start the cooling operation by natural circulation, it is necessary to shift the refrigerant in the refrigerant circuit to a predetermined pressure region not less than the pressure corresponding to the outdoor temperature and not more than the pressure corresponding to the indoor temperature.

  Therefore, an object of the present invention is to provide an air conditioner, an operation control method for the air conditioner, and a cooling system capable of stably and quickly starting the natural circulation in a natural circulation cycle.

  In order to solve such problems, the present invention is lower than the compressor, the first heat exchanger that exchanges heat with the first heat transfer medium on the heat source side, the expansion valve, and the first heat exchanger. A bypass pipe that bypasses the compressor is provided in an annular refrigerant circuit that is installed in a position and is sequentially connected to a second heat transfer medium on the use side and a second heat exchanger that performs heat exchange. In the air conditioner, the compressor, the first heat exchanger, the expansion valve, the forced circulation cycle for circulating the refrigerant between the second heat exchanger, the bypass pipe, and the first An air conditioner capable of operating by switching between a natural circulation cycle for circulating a refrigerant according to a density difference between a heat exchanger, the expansion valve, and the second heat exchanger, and starting the natural circulation cycle Sometimes the second heat carrier medium on the use side flowing into the second heat exchanger And characterized in that the flow rate is increased from a predetermined flow rate.

  According to the present invention, it is possible to provide an air conditioner, an operation control method for an air conditioner, and a cooling system that can stably and quickly start the natural circulation in a natural circulation cycle.

It is a systematic diagram of the air harmony device concerning this embodiment. It is a systematic diagram which shows the flow of the refrigerant | coolant and a heat transfer medium at the time of the cooling operation (forced circulation) of the air conditioning apparatus which concerns on this embodiment. It is a systematic diagram which shows the flow of the refrigerant | coolant and a heat transfer medium at the time of the cooling operation (natural circulation) of the air conditioning apparatus which concerns on this embodiment. It is a flowchart explaining the control at the time of starting of an air conditioning apparatus. It is a flowchart explaining the control at the time of starting of an air conditioning apparatus. It is a flowchart explaining the control in switching operation to natural circulation. It is an example of the figure which shows the relationship between the pressure and enthalpy at the time of air_conditionaing | cooling operation (natural circulation). It is an example which shows the relationship between the change of the outdoor temperature for one year, and a cooling load.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

≪Air conditioner≫
FIG. 1 is a system diagram of an air conditioner S according to the present embodiment.
The air conditioner S includes a refrigerant circuit 10 in which a refrigerant circulates, an outdoor unit 1 installed outside the room (outside the air-conditioned space), an indoor unit 3 installed inside the room (the air-conditioned space), and a control device 5. And.
The air conditioner S has a function of performing “cooling operation” for cooling the room in which the indoor unit 3 is arranged and “heating operation” for heating the room in which the indoor unit 3 is arranged.
Furthermore, the “cooling operation” includes a cooling operation by a forced circulation cycle in which the refrigerant in the refrigerant circuit 10 is circulated by the compressor 11 described later (hereinafter referred to as “cooling operation (forced circulation)”), and a refrigerant due to a difference in refrigerant density. It has a function of performing a cooling operation (hereinafter referred to as “cooling operation (natural circulation)”) by a natural circulation cycle in which the refrigerant of the circuit 10 is circulated.

  The air conditioner S includes a refrigerant circuit 10 through which the refrigerant circulates and a heat transfer medium circulation circuit 30 through which the heat transfer medium circulates.

<Refrigerant circuit>
The refrigerant circuit 10 provided in the outdoor unit 1 includes a compressor 11 that compresses the refrigerant into a high-pressure refrigerant, a four-way valve 12 that switches a refrigerant flow direction between a cooling operation and a heating operation, and an outdoor heat exchanger 13. And the auxiliary outdoor heat exchanger 14, the outdoor heat exchanger 13 and the outdoor fan 13a for blowing outdoor air to the auxiliary outdoor heat exchanger 14, the expansion valve 15 for reducing the pressure of the refrigerant, and the flow rate of the refrigerant. The refrigerant | coolant flow control valve 16, the primary side fluid flow path 17a of the intermediate heat exchanger 17 which performs heat exchange with a heat transfer medium, electromagnetic valves 24 and 25, two-way valves 22 and 23, and the bypass valve 21 It is prepared for. These devices, valves, and the like are connected in an annular shape by a refrigerant pipe.

  The compressor 11 is a variable capacity compressor capable of capacity control. As such a compressor, a piston type, a rotary type, a scroll type, a screw type, or a centrifugal type can be adopted. Specifically, the compressor 11 is a scroll type compressor, and capacity control is possible by inverter control, and the rotational speed is variable from low speed to high speed.

  The outdoor heat exchanger 13 and the auxiliary outdoor heat exchanger 14 exchange heat between outdoor air as a heat source side heat medium blown from the outdoor fan 13a and refrigerant flowing in the heat exchangers 13 and 14. For example, a fin tube type is used. The auxiliary outdoor heat exchanger 14 is connected in parallel to the outdoor heat exchanger 13, and is provided before and after the auxiliary outdoor heat exchanger 14 (upstream and downstream sides of the refrigerant flow during the cooling operation). By opening and closing the electromagnetic valves 24 and 25, it is possible to switch between the case where the refrigerant flows only to the outdoor heat exchanger 13 and the case where the refrigerant flows to both the outdoor heat exchanger 13 and the auxiliary outdoor heat exchanger 14. It has become.

  A bypass pipe 21a for bypassing the compressor 11 is provided, and a bypass valve 21 that is a two-way valve is attached to the bypass pipe 21a. Therefore, by controlling the opening and closing of the two-way valves 22 and 23 and the bypass valve 21 provided before and after the compressor 11, the flow path through which the refrigerant flows passes through the compressor 11 and bypasses the compressor 11. You can switch to and from.

  Further, a bypass pipe 16a that bypasses the expansion valve 15 is provided, and a refrigerant flow control valve 16 is attached to the bypass pipe 16a. That is, the expansion valve 15 and the refrigerant flow control valve 16 are connected in parallel. Therefore, by controlling the opening / closing of the expansion valve 15 and the refrigerant flow control valve 16, the refrigerant can be selectively passed through the expansion valve 15 and the refrigerant flow control valve 16.

  The intermediate heat exchanger 17 performs heat exchange between the refrigerant flowing through the primary fluid flow path 17a and the heat transfer medium flowing through the secondary fluid flow path 17b. A vessel or the like is used. The intermediate heat exchanger 17 is installed at a position lower than the outdoor heat exchanger 13 and the auxiliary outdoor heat exchanger 14. This is for performing cooling operation by a natural circulation cycle.

As the refrigerant, HFC refrigerant, HFO-1234yf, HFO-1234ze, natural refrigerant (for example, CO ₂ refrigerant), or the like can be used.

<Heat transfer medium circulation circuit>
A heat transfer medium circulation circuit 30 provided from the outdoor unit 1 to the indoor unit 3 includes a circulation pump 31 for feeding the heat transfer medium, a three-way valve 32, and an indoor heat exchanger 33 installed in the indoor unit 3. And an indoor fan 33a that blows indoor air to the indoor heat exchanger 33 and a secondary fluid flow path 17b of the intermediate heat exchanger 17 that performs heat exchange with the refrigerant are sequentially connected by a pipe, It is the circuit formed in.

The indoor heat exchanger 33 performs heat exchange between indoor air as a use-side heat medium blown from the indoor fan 33a and a heat transfer medium flowing in the indoor heat exchanger 33. For example, a fin tube The formula is used.
The heat transfer medium flowing in the heat transfer medium circulation circuit 30 exchanges heat with the indoor air in the room where the indoor unit 3 is disposed via the indoor heat exchanger 33, thereby cooling or heating the room. The capacity adjustment of the indoor heat exchanger 33 is controlled by the rotational speed of the circulation pump 31, the opening degree of the three-way valve 32, and the rotational speed of the indoor fan 33a.

  Note that water or brine (antifreeze) such as ethylene glycol can be used as the heat transfer medium.

<Control device>
In addition, the air conditioning apparatus S includes a control device 5.
The control device 5 determines the operation mode of the air conditioner S, and according to the determined operation mode, various valves (four-way valve 12, expansion valve 15, refrigerant flow rate control valve 16, bypass valve 21, two-way valves 22, 23, electromagnetic The state (opening) of the valves 24 and 25, the three-way valve 32), the rotational speed of the circulation pump 31, the rotational speed of the compressor 11, and the rotational speeds of the fans (outdoor fan 13a, indoor fan 33a) of each heat exchanger. It has the function to control and control various operations of the air conditioner S.

The air conditioning apparatus S includes a temperature sensor 41 for detecting the outdoor temperature _{T OA,} a temperature sensor 42 for detecting the indoor temperature _{T RM,} a temperature sensor 43 for detecting an inlet refrigerant temperature _{T EVIN} intermediate heat exchanger 17 _And a temperature sensor 44 that detects the outlet refrigerant temperature _TEVOUT of the intermediate heat exchanger 17, and the temperature detection signals detected by the temperature sensors 41, 42, 43, 44 are input to the control device 5.

<Cooling operation (forced circulation)>
First, operation | movement of the air conditioning apparatus S at the time of air_conditionaing | cooling operation (forced circulation) is demonstrated using FIG. FIG. 2 is a system diagram illustrating the flow of the refrigerant and the heat transfer medium during the cooling operation (forced circulation) of the air-conditioning apparatus S according to the present embodiment.
As shown in FIG. 2, the control device 5 controls the refrigerant flow rate control valve 16, the bypass valve 21, the electromagnetic valve 24, and the electromagnetic valve 25 to be closed and the two-way valve 22 and the two-way valve 23 to be opened. To do. The control device 5 controls the opening (throttle) of the expansion valve 15 and controls the four-way valve 12 to be in the cooling operation position. The control device 5 controls the rotational speeds of the compressor 11 and the outdoor fan 13a.
In the cooling operation (forced circulation), the auxiliary outdoor heat exchanger 14 stores excess refrigerant.

The high-temperature and high-pressure refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 13 that functions as a condenser. The refrigerant flowing through the outdoor heat exchanger 13 dissipates heat by exchanging heat with the outdoor air sent by the outdoor fan 13a, and becomes a high-pressure liquid refrigerant. The liquid refrigerant that has flowed out of the outdoor heat exchanger 13 is depressurized by the expansion valve 15 and enters a low-temperature and low-pressure gas-liquid two-phase state.
Then, the low-temperature and low-pressure refrigerant flows into the primary fluid passage 17a of the intermediate heat exchanger 17 that functions as an evaporator. The refrigerant flowing through the primary side fluid flow path 17a of the intermediate heat exchanger 17 is heated by the heat transfer medium by exchanging heat with the heat transfer medium flowing through the secondary side fluid flow path 17b of the intermediate heat exchanger 17. It evaporates and is sent to the compressor 11 and circulates through the refrigerant circuit 10.

  Next, the heat transfer medium circulation circuit 30 will be described. The control device 5 controls the rotational speeds of the circulation pump 31 and the indoor fan 33a. The control device 5 controls the opening degree of the three-way valve 32.

The heat transfer medium cooled by flowing through the secondary fluid passage 17 b of the intermediate heat exchanger 17 flows into the indoor heat exchanger 33 of the indoor unit 3 by driving the circulation pump 31. The heat transfer medium flowing through the indoor heat exchanger 33 absorbs heat by exchanging heat with air (indoor air) sent by the indoor fan 33a. Then, the heat transfer medium that has absorbed heat is sent from the indoor heat exchanger 33 to the secondary fluid flow path 17b of the intermediate heat exchanger 17 and circulates in the heat transfer medium circulation circuit 30.
As described above, the heat transfer medium absorbs heat in the indoor heat exchanger 33 of the indoor unit 3, whereby the air (room air) is cooled and the room (air-conditioned space) is cooled.

<Heating operation>
During the heating operation, the refrigerant is caused to flow in the opposite direction to that during the cooling operation (forced circulation) shown in FIG. That is, by switching the four-way valve 12 of the refrigerant circuit 10, the high-temperature and high-pressure refrigerant discharged from the compressor 11 is sent to the intermediate heat exchanger 17, and the intermediate heat exchanger 17 functions as a condenser. And it decompresses with the expansion valve 15, and the outdoor heat exchanger 13 functions as an evaporator.
The heat transfer medium heated by the intermediate heat exchanger 17 flows into the indoor heat exchanger 33 and dissipates heat by exchanging heat with the air (indoor air) sent by the indoor fan 33a. The air-conditioned space is heated.

<Cooling operation (natural circulation)>
Next, operation | movement of the air conditioning apparatus S at the time of air_conditionaing | cooling operation (natural circulation) is demonstrated using FIG. FIG. 3 is a system diagram showing the flow of the refrigerant and the heat transfer medium during the cooling operation (natural circulation) of the air-conditioning apparatus S according to the present embodiment.
As illustrated in FIG. 3, the control device 5 performs control so that the expansion valve 15, the two-way valve 22, and the two-way valve 23 are closed and the bypass valve 21, the electromagnetic valve 24, and the electromagnetic valve 25 are opened. The control device 5 controls the opening degree of the refrigerant flow control valve 16. The control device 5 controls the rotational speed of the outdoor fan 13a. The compressor 11 is stopped.
In the cooling operation (natural circulation), the auxiliary outdoor heat exchanger 14 functions as a condenser together with the outdoor heat exchanger 13.

The refrigerant in the outdoor heat exchanger 13 and the auxiliary outdoor heat exchanger 14 functioning as a condenser dissipates heat to the outdoor air, condenses and liquefies. The liquid refrigerant having a high density descends under the influence of gravity, passes through the refrigerant flow rate control valve 16, and flows into the primary side fluid passage 17a of the intermediate heat exchanger 17 functioning as an evaporator. The refrigerant flowing through the primary fluid flow path 17a of the intermediate heat exchanger 17 absorbs heat from the heat transfer medium by exchanging heat with the heat transfer medium flowing through the secondary fluid flow path 17b of the intermediate heat exchanger 17. Evaporate and gasify. At this time, since a pressure gradient is generated due to the density difference of the refrigerant, the evaporated refrigerant flows through the bypass pipe 21a toward the outdoor heat exchanger 13 and the auxiliary outdoor heat exchanger 14, and circulates in the refrigerant circuit 10. To do.
The heat transfer medium circulation circuit 30 is the same as the operation of the heat transfer medium circulation circuit 30 during the cooling operation (forced circulation), and a description thereof will be omitted.

  For example, when the indoor set temperature is 25 ° C. and the indoor / outdoor temperature difference that allows cooling operation (natural circulation) is 5 ° C., as shown in FIG. The outdoor temperature is below 20 ° C., especially around April, May, September and October, but natural circulation operation is possible even in winter when the indoor heat load is high.

<Control when starting the air conditioner>
The operation mode of the air conditioner S executed by the control device 5 will be described. 4 and 5 are flowcharts for explaining the control at the time of activation of the air conditioner S. In addition, the case where the air conditioning apparatus S has stopped and the air conditioning operation of the air conditioning apparatus S is started will be described.

In step S <b> 101, the control device 5 drives the outdoor fan 13 a of the outdoor unit 1, takes outdoor air into the outdoor unit 1, and detects the outdoor temperature _TOA with the temperature sensor 41. Further, the control device 5 drives the indoor fan 33 a of the indoor unit 3 to take in indoor air into the indoor unit 3, and detects the indoor temperature _TRM with the temperature sensor 42. Moreover, the control apparatus 5 acquires set temperature _TRPS which is indoor target temperature. The set temperature _TRPS is input to the control device 5 when the user operates a remote controller (not shown) installed indoors, for example.

In step S102, the control unit 5 determines whether the indoor temperature _{T RM} is higher than the set temperature _{T RPS.} If the indoor temperature _{T RM} is higher than the set temperature _{T RPS} (S102 · Yes), the processing of the control unit 5 proceeds to step S104. When the room temperature T _RM is not higher than the set temperature T _RPS (No in S102), the process of the control device 5 proceeds to Step S103.

  In step S103, the control apparatus 5 performs the heating operation (forced circulation) of the air conditioning apparatus S. Thus, when the indoor set temperature is higher than the room temperature, the heating operation (forced circulation) is executed.

In step S104, the control unit 5, the temperature difference between the indoor temperature _{T RM} and the outdoor temperature _{T OA (T} RM _{-T OA)} is equal to or greater than a predetermined value PS1. If the temperature difference _(T RM _{-T OA)} is larger than the predetermined value PS1 (S104 · Yes), the processing of the control unit 5 proceeds to step S105. If the temperature difference _(T RM _{-T OA)} is not greater than the predetermined value PS1 (S104 · No), the processing of the control unit 5 proceeds to step S106.

In step S105, the control device 5 determines whether or not the temperature difference (T _RM −T _RPS ) between the room temperature T _RM and the set temperature T _RPS is greater than a predetermined value PS2. When the temperature difference (T _RM −T _RPS ) is larger than the predetermined value PS2 (Yes in S105), the process of the control device 5 proceeds to step S107. When the temperature difference (T _RM −T _RPS ) is not greater than the predetermined value PS2 (No in S105), the process of the control device 5 proceeds to Step S106.

In step S106, the control device 5 performs the cooling operation (forced circulation) of the air conditioner S.
As described above, when the cooling operation by the natural circulation cycle cannot be performed (S104 / No) or when the cooling load is large (S105 / Yes), the cooling operation (forced circulation) for driving the compressor 11 is executed.

  In step S107, the control device 5 determines whether or not the operation mode (previous operation mode) before the air conditioner S is stopped is the cooling operation (natural circulation). When the operation mode before the stop is the cooling operation (natural circulation) (Yes in S107), the process of the control device 5 proceeds to step S109 in FIG. When the operation mode before the stop is not the cooling operation (natural circulation) (No in S107), the process of the control device 5 proceeds to Step S108.

  In step S108, the control device 5 performs a switching operation to the cooling operation (natural circulation). The switching operation will be described later with reference to FIG. Then, the process of the control device 5 proceeds to step S109 in FIG.

In step S _<b> 109, the control device 5 detects the inlet refrigerant temperature T _EVIN of the intermediate heat exchanger 17 with the temperature sensor 43. Further, the control device 5 calculates the pressure ratio K.
Here, it demonstrates using FIG. FIG. 7 is an example of a diagram illustrating a relationship between pressure and enthalpy during cooling operation (natural circulation).
First, the control unit 5, based on the indoor temperature _{T RM,} calculates the room temperature reference pressure _{P RM.} Further, the control unit 5, based on the outdoor temperature _{T OA,} calculates the outdoor temperature reference pressure _{P OA.} Further, the control unit 5, based on the inlet refrigerant temperature _{T EVIN,} calculates the refrigerant temperature reference pressure _{P ref.}
Here, the indoor temperature reference pressure P _RM is the pressure of the refrigerant when the refrigerant in the refrigerant circuit 10 is the indoor temperature T _RM, and is calculated based on the physical property value of the refrigerant enclosed in the refrigerant circuit 10. . The outdoor temperature reference pressure _POA is the pressure of the refrigerant when the refrigerant in the refrigerant circuit 10 is the outdoor temperature _TOA, and is calculated based on the physical property value of the refrigerant sealed in the refrigerant circuit 10.
The refrigerant temperature reference pressure P _ref, a pressure corresponding to the current refrigerant temperature in the refrigerant circuit 10, as the reference temperature, a pressure of the refrigerant example at the inlet refrigerant temperature T _EVIN intermediate heat exchanger 17, the refrigerant It is calculated based on the physical property value of the refrigerant sealed in the circuit 10.
Then, as shown in FIG. 7, the pressure difference (P _RM -P _OA ) between the indoor temperature reference pressure P _RM and the outdoor temperature reference pressure P _OA is ΔP, the refrigerant temperature reference pressure P _ref and the outdoor temperature reference pressure P _OA. And the pressure ratio K is ΔP1 / ΔP, and the control device 5 calculates the pressure ratio K. The pressure difference (P _ref −P _OA ) is ΔP1.

  In step S110, the control device 5 determines whether or not the pressure ratio K calculated in step S109 is equal to or greater than a predetermined value PS3. When the pressure ratio K is equal to or greater than the predetermined value PS3 (S110 · Yes), the process of the control device 5 proceeds to step S115. When the pressure ratio K is not equal to or greater than the predetermined value PS3 (S110 · No), the process of the control device 5 proceeds to step S111.

In step S111, the control device 5 outputs a startup operation command for cooling operation (natural circulation).
Here, the start-up operation is a start-up operation for quickly starting the cooling operation (natural circulation), and specifically, processing from step S112 to step S114 described later.

  In step S112, the control device 5 opens the expansion valve 15 and closes the opening of the refrigerant flow rate control valve 16. Alternatively, the expansion valve 15 is closed and the opening of the refrigerant flow control valve 16 is reduced. Further, the rotational speed of the circulation pump 31 is increased to increase the flow rate of the circulating heat transfer medium. In addition, the three-way valve 32 is switched so that the amount of the heat transfer medium circulating between the intermediate heat exchanger 17 and the indoor heat exchanger 33 increases.

In step S113, the control device 5 detects the inlet refrigerant temperature T _EVIN of the intermediate heat exchanger 17 with the temperature sensor 43, and detects the outlet refrigerant temperature T _EVOUT of the intermediate heat exchanger 17 with the temperature sensor 44. Further, the control device 5 calculates the _{inlet /} outlet refrigerant temperature difference ΔEV (= T _EVOUT −T _EVIN ) of the intermediate heat exchanger 17.

In step S114, the control device 5 determines whether or not the inlet / outlet refrigerant temperature difference ΔEV (= T _EVOUT −T _EVIN ) is greater than a predetermined value PS4. When the inlet / outlet refrigerant temperature difference ΔEV (= T _EVOUT −T _EVIN ) is larger than the predetermined value PS4 (S114 · Yes), the processing of the control device 5 proceeds to step S116. When the inlet / outlet refrigerant temperature difference ΔEV (= T _EVOUT −T _EVIN ) is not larger than the predetermined value PS4 (No in S114), the process of the control device 5 returns to Step S113.

  In step S115, the control device 5 determines that the start-up operation is unnecessary. Then, the process of the control device 5 proceeds to step S116.

  In step S116, the control device 5 sets the opening of the refrigerant flow control valve 16 to flow control (or full open). Further, the rotational speed of the circulation pump 31 is driven at the rated speed of the cooling operation (natural circulation). The same applies to the three-way valve 32.

  In step S117, the control device 5 starts the cooling operation (natural circulation) of the air conditioner S.

Next, the switching operation to the natural circulation shown in step S108 of FIG. 4 will be described with reference to FIG.
In step S201, the control device 5 closes the refrigerant flow control valve 16, the two-way valve 22, and the two-way valve 23. In this state, the bypass valve 21, the electromagnetic valve 24, and the electromagnetic valve 25 are closed, and the expansion valve 15 is opened.

  In step S202, the control device 5 changes the opening degree of the electromagnetic valve 25. Thereby, the liquid refrigerant stored in the auxiliary outdoor heat exchanger 14 is discharged from the electromagnetic valve 25 through the expansion valve 15 to the inlet side of the intermediate heat exchanger 17, and to the inlet side of the intermediate heat exchanger 17. A coolant liquid column is formed.

In step S203, the control device 5 determines the refrigerant pressure in the region sandwiched between the solenoid valve 24 and the solenoid valve 25 (refrigerant pressure in the auxiliary outdoor heat exchanger 14) and the refrigerant pressure in the other refrigerant circuits 10 (for example, , The pressure difference between the refrigerant and the pressure of the refrigerant in the outdoor heat exchanger 13 is detected, and it is determined whether the pressure difference is within a specified value. Each pressure is detected by a pressure sensor (not shown).
When the pressure difference is within the specified value (S203 / Yes), the process of the control device 5 proceeds to step S204. When the pressure difference is not within the specified value (No at S203), the process of the control device 5 returns to Step S202.
Thus, the opening degree of the solenoid valve 25 is changed until the pressure difference is within the specified value, and the refrigerant stored in the auxiliary outdoor heat exchanger 14 is released.

In step S <b> 204, the control device 5 fully opens the solenoid valves 24 and 25.
In step S205, the control device 5 opens the bypass valve 21. And the process of the control apparatus 5 complete | finishes switching operation to the air_conditionaing | cooling operation (natural circulation) shown to step S108, and progresses to step S109 of FIG.

<Operational effects of the air conditioner S>
Next, the effect of the air conditioning apparatus S which concerns on this embodiment is demonstrated.
In order to start the cooling operation by the natural circulation cycle of the air conditioner S, it is necessary to shift the pressure of the refrigerant in the refrigerant circuit 10 to a pressure region in which natural circulation is possible (pressure region indicated by the cycle in FIG. 7). is there.
However, for example, in a state where the air conditioner S is stopped, the pressure of the refrigerant in the refrigerant circuit 10 (that is, equivalent to the refrigerant temperature reference pressure _Pref ) is equal to the pressure that is balanced with the outdoor temperature _TOA (that is, the outdoor temperature). It corresponds to the temperature reference pressure _POA ).

As shown in step S112, the air conditioner S according to the present embodiment increases the rotational speed of the circulation pump 31 and increases the flow rate of the heat transfer medium flowing into the intermediate heat exchanger 17 in the start-up operation. Thus, heat exchange between the refrigerant and the heat transfer medium in the intermediate heat exchanger 17 is promoted, and the refrigerant is quickly heated by the heat transfer medium. Thereby, the pressure of the refrigerant in the refrigerant circuit 10 is also increased, and can be quickly shifted to a pressure region where natural circulation is possible. Here, the heating amount is determined by the amount of refrigerant enclosed in the cycle, the heat capacity of the equipment constituting the cycle, and the like.
Thereby, since the air conditioning apparatus S which concerns on this embodiment starts the cooling operation by a natural circulation cycle rapidly, and air-conditions a room | chamber interior, a user's comfort improves. In addition, the start-up time can be shortened and energy saving is improved.

  Further, as shown in step S112, the air conditioner S according to the present embodiment restricts the opening by the expansion valve 15 and the refrigerant flow rate control valve 16 in the start-up operation, so that the inlet side of the intermediate heat exchanger 17 Since the refrigerant liquid column can be formed in the cooling operation, it is possible to easily start the cooling operation by the natural circulation cycle.

Moreover, as shown to step S113 and step S114, the air conditioning apparatus S which concerns on this embodiment complete | finishes start-up operation, when the inlet-outlet temperature difference (DELTA) EV of the intermediate heat exchanger 17 becomes larger than predetermined value (PS4). Is determined.
When the refrigerant is heated by the heat transfer medium in the intermediate heat exchanger 17, both the inlet refrigerant temperature T _EVIN and the outlet refrigerant temperature T _EVOUT rise, and the inlet / outlet temperature difference ΔEV remains small. When the refrigerant is further heated, the refrigerant evaporates and gasifies, and flows from the outlet side of the intermediate heat exchanger 17 to the outdoor heat exchanger 13 and the auxiliary outdoor heat exchanger 14 through the bypass pipe 21a. For this reason, when the refrigerant evaporates and _{gasifies, that} is, when the natural circulation of the refrigerant is started, the outlet refrigerant temperature _TEVOUT suddenly rises. On the other hand, a refrigerant liquid column is formed on the inlet side of the intermediate heat exchanger 17, and the inlet refrigerant temperature T _EVIN rises gently.
In this way, by determining whether or not the inlet / outlet temperature difference ΔEV (= T _EVOUT −T _EVIN ) is larger than the predetermined value (PS4), the natural circulation of the refrigerant is started, that is, the start-up operation is finished. Whether or not to do so can be determined.

≪Modification≫
In addition, the air conditioning apparatus S which concerns on this embodiment is not limited to the structure of the said embodiment, A various change is possible within the range which does not deviate from the meaning of invention.

  For example, in the above embodiment, it has been described that the auxiliary refrigerant is stored in the cooling operation by the forced circulation cycle and the auxiliary outdoor heat exchanger 14 that functions as a condenser in the cooling operation by the natural circulation cycle is provided. It is not restricted to this, The refrigerant | coolant supply apparatus (not shown) which adjusts the refrigerant | coolant amount in the refrigerant circuit 10 according to the driving | running state of a cycle may be sufficient.

  In the above-described embodiment, the refrigerant is passed through the expansion valve 15 during the cooling operation by the forced circulation cycle, and the refrigerant is passed through the refrigerant flow control valve 16 during the cooling operation by the natural circulation cycle. However, the present invention is not limited to this, and may be constituted by one pressure reducing valve (or one refrigerant flow rate control valve).

In the above-described embodiment, the air-conditioning apparatus S that supplies the heat transfer medium cooled by the intermediate heat exchanger 17 to the indoor heat exchanger 33 and cools (cools) the room (the air-conditioned space) has been described. However, the present invention is not limited to this, and the present invention may be applied to a chiller system (cooling system) that supplies a heat transfer medium cooled by the intermediate heat exchanger 17 to an apparatus (not shown).
According to the present invention, the time required for starting the cooling operation by the natural circulation cycle can be shortened, so that the present invention can also be applied to a device (for example, a data center) that can be left in a poorly cooled state.

  In the above embodiment, the intermediate heat exchanger 17 and the heat transfer medium circulation circuit 30 are provided, and the rotation speed of the circulation pump 31 for feeding the heat transfer medium is increased during start-up operation. However, it is not limited to this. For example, the intermediate heat exchanger 17 and the heat transfer medium circulation circuit 30 are not provided, and the refrigerant is circulated through the indoor heat exchanger 33 instead of the intermediate heat exchanger 17. The rotational speed of 33a may be increased. In this configuration, the indoor heat exchanger 33 needs to be disposed at a position lower than the outdoor heat exchanger 13 in order to allow natural circulation of the refrigerant.

DESCRIPTION OF SYMBOLS S Air conditioning apparatus 1 Outdoor unit 3 Indoor unit 5 Control apparatus 10 Refrigerant circuit 11 Compressor 12 Four-way valve 13 Outdoor heat exchanger (1st heat exchanger)
13a Outdoor fan 14 Auxiliary outdoor heat exchanger (first heat exchanger)
15 Expansion valve 16 Refrigerant flow control valve (expansion valve)
16a Bypass piping 17 Intermediate heat exchanger (second heat exchanger)
17a Primary fluid passage 17b Secondary fluid passage 21 Bypass valve 21a Bypass piping 22, 23 Two-way valve 24, 25 Solenoid valve 30 Heat transfer medium circulation circuit 31 Circulation pump 32 Three-way valve 33 Indoor heat exchanger 33a Indoor fan 41, 42 Temperature sensor 43 Temperature sensor (first temperature detection means)
44 Temperature sensor (second temperature detection means)

In order to solve such a problem, an air conditioner according to the present invention includes a compressor, a first heat exchanger that performs heat exchange with a first heat transfer medium on a heat source side, an expansion valve, and the first is installed at a position lower than the heat exchanger, and a second heat exchanger for performing a second heat-carrying medium and the heat exchanger of the use-side is a liquid are sequentially connected to the refrigerant circuit which is formed in an annular shape, the compressor Compressor bypass piping to be bypassed, a third heat exchanger connected in parallel to the first heat exchanger, on-off valves provided on the upstream side and the downstream side of the third heat exchanger, and the expansion A refrigerant flow rate control valve provided in an expansion valve bypass pipe that bypasses the valve, and closes the on-off valve to store excess refrigerant in the third heat exchanger, and the compressor, the first a heat exchanger, and the expansion valve, a phase change to a refrigerant between said second heat exchanger A forced circulation cycle to ring, and opening the on-off valve, and the compressor bypass pipe, wherein a first heat exchanger and the third heat exchanger, said refrigerant flow rate control valve, the second heat exchanger a phase change to a refrigerant between the vessel by circulating by density difference and natural circulation cycle you cooling is operable by switching the startup of the cooling operation by natural circulation cycle, in the second heat exchanger and performing start-up operation for increasing the predetermined flow rate is the flow rate after starting the cooling operation of the flow rate of the use-side of the second heat transporting medium flowing by the natural circulation cycle.

DESCRIPTION OF SYMBOLS S Air conditioning apparatus 1 Outdoor unit 3 Indoor unit 5 Control apparatus 10 Refrigerant circuit 11 Compressor 12 Four-way valve 13 Outdoor heat exchanger (1st heat exchanger)
13a Outdoor fan 14 Auxiliary outdoor heat exchanger ( third heat exchanger)
15 Expansion valve 16 Refrigerant flow control valve 16a Bypass piping (Expansion valve bypass piping)
17 Intermediate heat exchanger (second heat exchanger)
17a Primary side fluid passage 17b Secondary side fluid passage 21 Bypass valve 21a Bypass piping (compressor bypass piping)
22, 23 Two-way valve 24, 25 Solenoid valve 30 Heat transfer medium circulation circuit 31 Circulation pump 32 Three-way valve 33 Indoor heat exchanger 33a Indoor fan 41, 42 Temperature sensor 43 Temperature sensor (first temperature detection means)
44 Temperature sensor (second temperature detection means)

Claims (6)

A compressor, a first heat exchanger that exchanges heat with the first heat transfer medium on the heat source side, an expansion valve, and a second heat transfer medium on the use side that is installed at a position lower than the first heat exchanger; In the air conditioner comprising a bypass circuit that bypasses the compressor in the annularly formed refrigerant circuit by sequentially connecting a second heat exchanger that performs heat exchange,
A forced circulation cycle for circulating refrigerant between the compressor, the first heat exchanger, the expansion valve, and the second heat exchanger;
An air conditioner that can be operated by switching between the bypass pipe, the first heat exchanger, the expansion valve, and a natural circulation cycle that circulates refrigerant according to a density difference between the second heat exchanger. And
An air conditioner that increases the flow rate of the second heat transfer medium on the use side flowing into the second heat exchanger from a predetermined flow rate when starting the natural circulation cycle. A first temperature detection means for detecting the inflow side temperature of the refrigerant flowing through the second heat exchanger; and a second temperature detection means for detecting the outflow side temperature;
When the temperature difference between the detected temperature of the first temperature detecting means and the detected temperature of the second temperature detecting means becomes larger than a predetermined value, the increased second heat on the use side flowing into the increased second heat exchanger. The air conditioner according to claim 1, wherein the flow rate of the transport medium is changed to the predetermined flow rate. At the start of the natural circulation cycle, the flow rate of the second heat transfer medium on the use side flowing into the second heat exchanger is increased from a predetermined flow rate, and the opening degree of the expansion valve is reduced from the predetermined opening degree. The air conditioning apparatus according to claim 1. A first temperature detection means for detecting the inflow side temperature of the refrigerant flowing through the second heat exchanger; and a second temperature detection means for detecting the outflow side temperature;
When the temperature difference between the detected temperature of the first temperature detecting means and the detected temperature of the second temperature detecting means exceeds a predetermined value, the opening of the expansion valve is changed to a predetermined opening. The air conditioning apparatus according to claim 3. A compressor, a first heat exchanger that exchanges heat with the first heat transfer medium on the heat source side, an expansion valve, and a second heat transfer medium on the use side that is installed at a position lower than the first heat exchanger; In the air conditioner comprising a bypass circuit that bypasses the compressor in the annularly formed refrigerant circuit by sequentially connecting a second heat exchanger that performs heat exchange,
A forced circulation cycle for circulating refrigerant between the compressor, the first heat exchanger, the expansion valve, and the second heat exchanger;
Operation of an air conditioner that can be operated by switching between the bypass piping, the first heat exchanger, the expansion valve, and a natural circulation cycle that circulates the refrigerant by density difference between the second heat exchanger. A control method,
An operation control method for an air conditioner, wherein the flow rate of the use-side second heat transfer medium flowing into the second heat exchanger is increased from a predetermined flow rate at the start of the natural circulation cycle. A compressor, a first heat exchanger that exchanges heat with the first heat transfer medium on the heat source side, an expansion valve, and a second heat transfer medium on the use side that is installed at a position lower than the first heat exchanger; In the cooling system comprising a bypass circuit that bypasses the compressor in a circularly formed refrigerant circuit that is sequentially connected to a second heat exchanger that performs heat exchange,
A forced circulation cycle for circulating refrigerant between the compressor, the first heat exchanger, the expansion valve, and the second heat exchanger;
A cooling system that can be operated by switching between the bypass piping, the first heat exchanger, the expansion valve, and a natural circulation cycle that circulates refrigerant according to a density difference between the second heat exchanger. ,
The cooling system characterized by increasing the flow rate of the use-side second heat transfer medium flowing into the second heat exchanger from a predetermined flow rate when the natural circulation cycle is started.

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