JP2001304660A - Air conditioner and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy-saving air conditioner and its control method for reliably converging the degree of superheating to a set value, even if the fresh air temperature is low, avoiding the unneeded decrease in the compression ratio of a compressor, extremely reducing very much the operation power, and improving the operating efficiency. SOLUTION: The degree of superheating of a refrigerant is detected, and the opening of an expansion valve 6 is controlled, so that the degree of superheating reaches a set value. When the expansion valve 6 is open fully while the degree of superheating does not decrease to the set value, the temperature of cooling water is increased. When the compression ratio of a compressor 1 becomes smaller than the allowable minimum compression ratio by detecting the compression ratio, however the temperature of cooling water is increased. When the temperature of cooling water cannot be increased, a condensation pressure regulating valve 4 is controlled to increase condensation pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for high heat generation equipment which needs cooling even when the outside air temperature is low such as in winter, and a control method therefor.

[0002]

2. Description of the Related Art In general, a so-called annual cooling type air conditioner is known as a device for cooling a room in which a high heat generating device such as a computer is installed over a year. The air conditioner includes a refrigeration cycle for circulating refrigerant through a compressor, a water-cooled condenser, an expansion valve, and an indoor heat exchanger, and a cooling water circulation cycle for circulating cooling water through a cooling water circulation pump, a cooling tower, and the water-cooled condenser. And

A high-temperature and high-pressure gas refrigerant discharged from a compressor is guided to a water-cooled condenser, and the gas refrigerant flowing into the water-cooled condenser is deprived of heat by cooling water flowing into the water-cooled condenser and liquefied. The liquid refrigerant flowing out of the water-cooled condenser is decompressed by the expansion valve and guided to the evaporator (indoor heat exchanger). In the evaporator, the decompressed liquid / gas mixed refrigerant deprives the indoor air of heat by the expansion valve. Vaporize. This gas refrigerant is sucked into the compressor, and the same cycle is repeated thereafter.

[0004] The cooling water that has passed through the water-cooled condenser is led to a cooling tower, where the heat of the cooling water (heat taken from the gas refrigerant) is released to the atmosphere. The cooling water whose temperature has decreased due to the heat radiation is supplied again to the water-cooled condenser by the cooling water circulation pump.

In such an air conditioner, the opening of the expansion valve is controlled so as to flow into the evaporator so that the degree of superheat of the refrigerant at the outlet of the evaporator becomes a set value in order to perform a stable operation of the refrigeration cycle. The amount of refrigerant is adjusted.

[0006]

However, when the outside air temperature decreases, the temperature of the cooling water decreases, and the condensing pressure of the refrigerant in the water-cooled condenser decreases accordingly. When the difference between the condensing pressure and the evaporating pressure becomes small, the flow rate of the refrigerant circulating in the refrigeration cycle decreases, and it becomes difficult to converge the degree of superheat to the set value. The compression ratio of the compressor may fall below the minimum allowable compression ratio.

[0007] The present invention has been made in view of the above circumstances,
The purpose is that even when the outside air temperature is low, the degree of superheat can be reliably converged to the set value, and the situation where the compression ratio of the compressor is unnecessarily reduced can be avoided. It is an object of the present invention to provide an air conditioner excellent in energy saving in which the operating power can be reduced as much as possible and the operating efficiency can be improved, and a control method thereof.

[0008]

An air conditioner according to the present invention comprises a refrigeration cycle for circulating a refrigerant through a compressor, a water-cooled condenser, a condensation pressure control valve, an expansion valve, and an indoor heat exchanger; A water circulation pump, a cooling tower, and a cooling water circulation cycle that circulates cooling water through the water-cooled condenser; a superheat degree detection unit that detects a superheat degree of the refrigerant at an outlet of the indoor heat exchanger; and a superheat degree detection unit that detects the superheat degree. Expansion valve control means for controlling the degree of opening of the expansion valve so that the degree of superheat reaches a set value, and the expansion valve is fully opened while the degree of superheat detected by the degree of superheat detection means does not decrease to the set value. A cooling water temperature control means for controlling the operation of the cooling water circulation cycle to increase the cooling water temperature in the cooling water circulation cycle, and a compression ratio detection for detecting a compression ratio of the compressor. Means for controlling the operation of the cooling water circulation cycle to increase the temperature of the cooling water in the cooling water circulation cycle when the compression ratio detected by the compression ratio detection means becomes smaller than a predetermined allowable minimum compression ratio. Cooling water temperature control means, determining means for determining whether or not the cooling water temperature can be raised by each of the cooling water temperature control means, and controlling the condensing pressure regulating valve when the determination result of the determining means is negative. Condensing pressure control means for increasing the condensing pressure of the refrigerant in the water-cooled condenser.

An air conditioner according to a second aspect of the present invention is the air conditioner according to the first aspect.
In the invention according to the first aspect, each cooling water temperature control means is limited. That is, each cooling water temperature control means controls the amount of water supplied by the cooling water circulation pump and the amount of cooling of the cooling tower.

[0010] The control method of the air conditioner according to the third aspect of the present invention includes a refrigeration cycle for circulating a refrigerant through a compressor, a water-cooled condenser, a condensing pressure control valve, an expansion valve, and an indoor heat exchanger; In an air conditioner including a cooling tower, and a cooling water circulation cycle that circulates cooling water through the water-cooled condenser, a step of detecting a degree of superheat of the refrigerant at an outlet of the indoor heat exchanger, and the detected degree of superheat is set. Controlling the degree of opening of the expansion valve to a value, and controlling the operation of the cooling water circulation cycle when the degree of superheat is not reduced to the set value and the expansion valve is fully opened. Raising the temperature of the cooling water in the cooling water circulation cycle, detecting the compression ratio of the compressor, and determining whether the detected compression ratio is a predetermined allowable value. Raising the cooling water temperature in the cooling water circulation cycle when the compression ratio becomes smaller than the minimum compression ratio; and determining whether or not the cooling water temperature can be raised. Controlling the pressure regulating valve to increase the condensation pressure of the refrigerant in the water-cooled condenser.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a heat exchanger 3 a of a water-cooled condenser 3 is connected to a refrigerant discharge port of the compressor 1 via a gas-side refrigerant pipe 2. This heat exchanger 3
a, an indoor heat exchanger (evaporator) 7 is connected via a condensing pressure control valve 4, a liquid-side refrigerant pipe 5, and a decompressor, for example, an expansion valve 6 with a variable opening, to which a compressor is connected. One refrigerant suction port is connected. That is, a refrigeration cycle for circulating the refrigerant through the compressor 1, the water-cooled condenser 3, the condensing pressure control valve 4, the liquid side refrigerant pipe 5, the expansion valve 6, and the indoor heat exchanger 7 is configured.

The condensing pressure control valve 4 is a so-called three-way valve, and a bypass pipe 2a is provided between the condensing pressure control valve 4 and the refrigerant inflow side of the heat exchanger 3a. The condensing pressure control valve 4 relatively increases or decreases the amount of the refrigerant passing through the heat exchanger 3a and the amount of the refrigerant passing through the bypass pipe 2a by changing the opening degree, whereby the condensing pressure of the refrigerant in the heat exchanger 3a is increased. Adjust

An indoor blower 8 is provided near the indoor heat exchanger 7. The indoor blower 8 has a function of sucking indoor air, passing it through the indoor heat exchanger 7, and blowing out the air (cool air) passing through the indoor heat exchanger 7 into the room.

On the other hand, a heat exchanger 14 of a cooling tower 13 is connected to a water discharge port of the cooling water circulation pump 11 via a water pipe 12. The cooling tower 13 includes, in addition to the heat exchanger 14, a sprinkler 15 that applies cooling water to the heat exchanger 14, and a sprinkler pump 1 that supplies cooling water accumulated in the bottom of the tower to the sprinkler 15.
6. A cooling tower blower 17 for introducing outside air to cool the cooling water is provided.

A water pipe 18 is connected to the heat exchanger 14 of the cooling tower 13.
Is connected to the heat exchanger 3b of the water-cooled condenser 3 through
The water inlet of the cooling water circulation pump 11 is connected to the heat exchanger 3b. That is, a cooling water circulation cycle for circulating the cooling water through the cooling water circulation pump 11, the cooling tower 13, and the water-cooled condenser 3 is configured.

The compressor 1 has a motor whose rotation speed is variable. The compressor drive unit 2 is used to drive the compressor 1.
1 is provided. The compressor drive unit 21 has a function of outputting a drive voltage for the motor of the compressor 1 and changing the frequency of the drive voltage. Due to this frequency change, the rotation speed of the motor of the compressor 1 changes, and accordingly, the capacity (also called capacity) of the compressor 1 changes.

A blower driving section 22 is connected to the indoor blower 8. The blower drive unit 22 has a function of outputting a drive voltage for the motor of the indoor blower 8 and changing the frequency of the drive voltage. Due to this frequency change, the amount of air blown by the indoor blower 8 changes.

A pump drive unit 23 is connected to the cooling water circulation pump 11. The pump drive unit 23 has a function of outputting a drive voltage to the motor of the cooling water circulation pump 11 and changing a frequency of the voltage. Due to this frequency change, the water supply amount of the cooling water circulation pump 11 changes.

In the gas-side refrigerant pipe 2, a pressure detecting unit 31 for detecting the discharged refrigerant pressure Pd is provided near the refrigerant discharge port of the compressor 1. Indoor heat exchanger 7 and compressor 1
A pressure detection unit 32 for detecting a suction refrigerant pressure Ps is provided in a pipe between the refrigerant suction port and the superheat degree detection unit 33 for detecting a superheat SH of the refrigerant in the indoor heat exchanger 7 (superheat) SH. Is provided.

Reference numeral 50 denotes a main control section for controlling the entire air conditioner. The main control unit 50 includes a compressor drive unit 21, a blower drive unit 22, a pressure detection unit 31, a pressure detection unit 32, a superheat degree detection unit 33, a condensing pressure control valve control unit 41, an expansion valve control unit 42, and cooling water. The temperature control unit 43 and the operation unit 51 are connected.

The condensing pressure control valve control unit 41 includes a main control unit 5
The condensing pressure control valve 4 is controlled according to a command from 0.
The expansion valve control unit 42 controls the opening degree of the expansion valve 6 according to a command from the main control unit 50. Cooling water temperature controller 43
Is a watering pump 1 according to a command from the main control unit 50.
6. Control the cooling tower blower 17 and the pump drive unit 23.

The main control unit 50 has the following means (1) to (6) as main functions. (1) Expansion valve control means for controlling the degree of opening of the expansion valve 6 together with the expansion valve control unit 42 such that the degree of superheat detected by the superheat degree detection unit 33 becomes a set value.

(2) When the expansion valve 6 is fully opened while the degree of superheat detected by the superheat degree detection section 33 does not decrease to the above set value, the operation of the cooling water circulation cycle is controlled together with the cooling water temperature control section 43. And a cooling water temperature control means for raising the cooling water temperature in the cooling water circulation cycle.

(3) Compression ratio detecting means for detecting the ratio between the discharged refrigerant pressure Pd detected by the pressure detecting unit 31 and the suction refrigerant pressure Ps detected by the pressure detecting unit 32 as the compression ratio of the compressor 1.

(4) When the compression ratio detected by the compression ratio detecting means becomes smaller than a predetermined minimum allowable compression ratio, the operation of the cooling water circulation cycle is controlled together with the cooling water temperature control section 43 to Cooling water temperature control means for increasing the temperature of the cooling water in the cooling water circulation cycle.

(5) Judgment means for judging whether or not the cooling water temperature can be raised by each of the cooling water temperature control means.

(6) When the judgment result of the judgment means is negative, the condensing pressure control valve 4 is operated together with the condensing pressure control valve controller 41.
Pressure control means for controlling the temperature of the water-cooled condenser 3 to increase the condensation pressure of the refrigerant.

Next, the operation of the above configuration will be described with reference to FIG. When the operation start operation is performed by the operation unit 51 (YES in step 101), the cooling operation is started (step 102).

That is, the compressor 1 includes a compressor driving section 21
, And discharges a high-temperature and high-pressure gas refrigerant.
This gas refrigerant is supplied to the water-cooled condenser 3 by the gas side refrigerant pipe 2.
, And exchanges heat with the cooling water passing through the heat exchanger 3b to condense to become a liquid refrigerant. This liquid refrigerant is guided to the expansion valve 6 by the liquid-side refrigerant pipe 5, where the pressure is reduced.
It becomes a low-temperature, low-pressure liquid-gas mixed refrigerant. Further, the liquid-gas mixed refrigerant is guided to the indoor heat exchanger (evaporator) 7, evaporates by exchanging heat with the indoor air sucked by the operation of the indoor blower 8, evaporates to a low-pressure gas, and becomes a compressor again. Inhaled into 1. The air that has passed through the indoor heat exchanger 7 is blown into the room as cooling air.

The cooling water having passed through the heat exchanger 3b of the water-cooled condenser 3 is guided to a cooling tower 13 by a cooling water circulation pump 11,
After heat exchange with the outside air, it reaches the water-cooled condenser 3 again.

During the cooling operation, the compression ratio of the compressor 1 is detected, and the degree of superheat of the refrigerant in the indoor heat exchanger 7 is detected (step 103).

If the detected compression ratio is not less than the minimum allowable compression ratio (NO in step 104), the detected degree of superheat is compared with a set value (step 105). When the degree of superheat is equal to or less than the set value (NO in step 105), or when the degree of superheat is higher than the set value and the expansion valve 6 is not fully opened (NO in step 106), the degree of opening of the expansion valve 6 is controlled. (Step 106). For example, if the degree of superheat is lower than the set value, the degree of opening of the expansion valve 6 is controlled to decrease. Due to the decrease in the opening degree, the amount of the refrigerant flowing into the indoor heat exchanger 7 decreases, and the degree of superheat changes in the upward direction. When the degree of superheat matches the set value, the opening of the expansion valve 6 at that time is maintained. When the degree of superheat becomes higher than the set value, the degree of opening of the expansion valve 6 is controlled to increase. Due to the increase in the opening degree, the amount of the refrigerant flowing into the indoor heat exchanger 7 increases, and the degree of superheat changes in a decreasing direction.

The superheat control in the direction of increasing the degree of opening of the expansion valve 6 reduces the compression power in the compressor 1, so that the operating power (power consumption) of the compressor 1 can be reduced as much as possible. There is an advantage that the operation efficiency can be improved.

However, when the outside air temperature decreases as in winter, the cooling water temperature in the cooling water circulation cycle decreases,
Accordingly, the condensation pressure of the refrigerant in the water-cooled condenser 3 decreases. When the difference between the condensing pressure and the evaporating pressure of the refrigerant in the indoor heat exchanger 7 decreases, the flow rate of the refrigerant circulating in the refrigeration cycle decreases, and the opening degree of the expansion valve 6 is limited. Above that, it becomes difficult to lower the degree of superheat. It is conceivable to use a large-capacity expansion valve as the expansion valve 6 to increase the limit of the opening degree. However, this causes a new problem that the superheat degree control cannot be performed with high accuracy. Absent.

If the degree of superheat is not reduced to the set value (YES in step 105) and the expansion valve 6 is fully opened (YES in step 107), it is determined whether the cooling water temperature control by the cooling water temperature controller 43 is at a limit. In short, it is determined whether the cooling water temperature can be increased by the cooling water temperature controller 43 (step 108).

The cooling water temperature control unit 43 controls the water supply amount of the cooling water circulating pump 11 (output voltage of the pump driving unit 23) and the cooling amount of the cooling tower 13 (operation / stop of the watering pump 16, cooling fan blower). 17 airflow). It is possible to raise the temperature of the cooling water by reducing the amount of water supplied by the cooling water circulation pump 11 or the amount of cooling of the cooling tower 13. There is a limit in securing.

If the cooling water temperature control by the cooling water temperature control unit 43 is not yet at the limit (NO in step 108), the cooling water temperature control unit 43 determines that the cooling water temperature can be raised, and The operating power (power consumption) of the cooling water circulation pump 11 is reduced, or the cooling tower blower 17
, The operating power (power consumption) of the cooling water is reduced, thereby increasing the cooling water temperature (step 109).

In this way, the decrease in the cooling water temperature due to the decrease in the outside air temperature is eliminated, and the decrease in the condensing pressure is suppressed. Due to this suppression, the difference between the condensing pressure and the evaporating pressure does not become small, and it is possible to avoid a situation in which the flow rate of the refrigerant circulating in the refrigeration cycle is reduced. . That is, the opening degree control of the expansion valve 6 becomes effective, and the superheat degree can be surely converged to the set value. As a result, stable and proper operation of the refrigeration cycle becomes possible.

If the cooling water temperature control by the cooling water temperature control unit 43 has already reached the limit (YES in step 108), it is determined that the cooling water temperature control unit 43 cannot raise the cooling water temperature. Below, the condensing pressure control valve 4 is controlled by the condensing pressure control valve control unit 41 to increase the condensing pressure of the refrigerant in the water-cooled condenser 3.

That is, when it is impossible to control the rise of the cooling water temperature, the condensing pressure is reduced by the condensing pressure control valve 4.
By directly and forcibly increasing the pressure, the situation in which the difference between the condensing pressure and the evaporating pressure becomes small is avoided, and the flow rate of the refrigerant circulating in the refrigeration cycle is not reduced. This allows the expansion valve 6 to be controlled with less than full opening. That is, the opening degree control of the expansion valve 6 becomes effective, and the superheat degree can be surely converged to the set value. As a result, stable and proper operation of the refrigeration cycle becomes possible.

On the other hand, the compressor 1 has a minimum allowable compression ratio in relation to the refrigerating machine oil (also referred to as lubricating oil). If the cooling water temperature becomes too low as the outside air temperature decreases, the condensing pressure will decrease. As a result, the compression ratio of the compressor 1 may fall below the minimum allowable compression ratio.

If the compression ratio falls below the minimum allowable compression ratio (YES in step 104), whether the cooling water temperature control by the cooling water temperature control unit 43 is at a limit (the cooling water temperature can be raised by the cooling water temperature control unit 43). Is determined (step 108).

If the cooling water temperature control by the cooling water temperature control unit 43 is not yet at the limit (NO in step 108), the cooling water temperature control unit 43 determines that the cooling water temperature can be increased. The operating power of the cooling water circulation pump 11 is reduced, or the operating power of the cooling tower blower 17 is reduced, whereby the temperature of the cooling water is increased (step 109).

In this manner, a decrease in the condensation pressure due to a decrease in the outside air temperature is eliminated. By this elimination, the situation where the compression ratio of the compressor 1 falls below the minimum allowable compression ratio is avoided. Thereby, stable and proper operation of the refrigeration cycle becomes possible, and the compressor 1 can be protected.

If the cooling water temperature control by the cooling water temperature control unit 43 has already reached the limit (YES in step 108), it is determined that the cooling water temperature control unit 43 cannot raise the cooling water temperature. Below, the condensing pressure control valve 4 is controlled by the condensing pressure control valve control unit 41 to increase the condensing pressure of the refrigerant in the water-cooled condenser 3.

That is, when it is not possible to control the rise of the cooling water temperature, the condensing pressure is directly and forcibly increased by the condensing pressure regulating valve 4 so that the compressor 1
Is prevented from falling below the allowable minimum compression ratio. Thereby, stable and proper operation of the refrigeration cycle becomes possible, and the compressor 1 can be protected.

As described above, even when the outside air temperature is low,
It is possible to ensure that the degree of superheat converges to the set value to enable stable and proper operation of the refrigeration cycle, and to protect the compressor 1 by avoiding a situation where the compression ratio of the compressor 1 is unnecessarily reduced. it can.

In the superheat control, in particular, instead of forcibly increasing the condensing pressure by using the condensing pressure regulating valve 4 from the beginning, first, the cooling water temperature is increased to compensate for the decrease in the condensing pressure. As a result, as a result, the cooling water circulation pump 11 and the watering pump 1 in the cooling water circulation cycle
6. The operating power (power consumption) of the cooling tower blower 17 and the like can be reduced. This leads to an improvement in operation efficiency and an air conditioner with excellent energy saving.

The present invention is not limited to the above embodiment, but can be variously modified without changing the gist.

[0050]

As described above, according to the present invention, even when the outside air temperature is low, the degree of superheat can be surely converged to the set value, and the compression ratio of the compressor is unnecessarily reduced. , And furthermore, it is possible to provide an air conditioner excellent in energy saving and capable of improving operating efficiency by reducing operating power as much as possible, and a control method thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of each embodiment.

FIG. 2 is a flowchart for explaining the operation of the first embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Gas side refrigerant piping, 3 ... Water-cooled condenser, 3
a, 3b: heat exchanger, 4: condensation pressure control valve, 5: liquid side refrigerant pipe, 6: expansion valve, 7: indoor heat exchanger (evaporator), 8
... indoor blower, 11 ... cooling water circulation pump, 12 ... water pipe,
13: cooling tower, 14: heat exchanger, 15: water sprinkler, 16 ...
Watering pump, 17: cooling tower blower, 18: water pipe, 21 ...
Compressor drive unit, 22 ... Blower drive unit, 23 ... Pump drive unit, 31, 32 ... Pressure detection unit, 33 ... Superheat degree detection unit, 4
1. Condensed pressure control valve controller, 42 ... Expansion valve controller, 43
... Cooling water temperature control unit, 50 ... Control unit, 51 ... Operation unit.

Continuing from the front page (72) Inventor Shigenori Waratani 3-4-1 Shibaura, Minato-ku, Tokyo Inside NTT Facilities Inc. (72) Inventor Minoru Okada 3-3-1 Toyosu, Koto-ku, Tokyo Stock Inside NTT Data (72) Inventor Takahiro Ezaki 3-3-3 Toyosu, Koto-ku, Tokyo Inside NTT Data Corporation (72) Inventor Toshihiro Nambu Koto-ku, Tokyo 3-3-3 Toyosu F-term in NTT Data Corporation (reference) 3L060 AA03 CC04 CC05 DD02 EE02 EE09

Claims (3)

[Claims] 1. A compressor, a water-cooled condenser, a condensation pressure control valve,
An expansion valve, a refrigeration cycle that circulates the refrigerant through the indoor heat exchanger, a cooling water circulation pump, a cooling tower, and a cooling water circulation cycle that circulates the cooling water through the water-cooled condenser; and a refrigerant cycle at the outlet of the indoor heat exchanger. Superheat degree detection means for detecting the degree of superheat, expansion valve control means for controlling the degree of opening of the expansion valve so that the degree of superheat detected by the superheat degree detection means becomes a set value, and detection by the superheat degree detection means Cooling water temperature control means for controlling the operation of the cooling water circulation cycle to increase the cooling water temperature in the cooling water circulation cycle when the expansion valve is fully opened while the degree of superheat is not lowered to the set value. A compression ratio detecting means for detecting a compression ratio of the compressor; and a compression ratio detected by the compression ratio detecting means being smaller than a predetermined allowable minimum compression ratio. At this time, cooling water temperature control means for controlling the operation of the cooling water circulation cycle to increase the cooling water temperature in the cooling water circulation cycle; and determining whether the cooling water temperature can be raised by each of the cooling water temperature control means. And a condensing pressure control means for controlling the condensing pressure regulating valve to increase the condensing pressure of the refrigerant in the water-cooled condenser when the judgment result of the judging means is negative. Air conditioner. 2. The air conditioner according to claim 1, wherein each of the cooling water temperature control means controls a water supply amount of the cooling water circulation pump and a cooling amount of the cooling tower. Machine. 3. A compressor, a water-cooled condenser, a condensing pressure control valve,
An air conditioner comprising an expansion valve, a refrigeration cycle for circulating a refrigerant through an indoor heat exchanger, and a cooling water circulation pump, a cooling tower, and a cooling water circulation cycle for circulating cooling water through the water-cooled condenser, wherein the indoor heat exchange is performed. Detecting the degree of superheat of the refrigerant at the outlet of the vessel; controlling the degree of opening of the expansion valve so that the detected degree of superheat becomes a set value; and the detected degree of superheat does not decrease to the set value. When the expansion valve is fully opened, controlling the operation of the cooling water circulation cycle to increase the temperature of the cooling water in the cooling water circulation cycle; and detecting a compression ratio of the compressor. When the set compression ratio becomes smaller than a predetermined allowable minimum compression ratio, the cooling water temperature in the cooling water circulation cycle is increased. Determining whether the cooling water temperature can be increased; and, if the determination result is negative, controlling the condensation pressure regulating valve to increase the condensation pressure of the refrigerant in the water-cooled condenser. A method for controlling an air conditioner, comprising: