JP4043756B2 - Air conditioner and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner and a control method thereof, and more particularly to an air conditioner used as an air conditioner for a computer room and a control method thereof.
[0002]
[Prior art]
FIG. 5 is a refrigerant circuit diagram showing a configuration of a conventional computer room air conditioner.
In this figure, 1 is a variable capacity compressor, 2 is a condensation side heat exchanger for condensing and liquefying the gas refrigerant discharged from the compressor 1, and 3 is a flow rate for reducing the pressure of the liquefied refrigerant from the condensation side heat exchanger 2. A variable expansion device, 4 is an evaporation side heat exchanger that evaporates the decompressed refrigerant, 5 is a refrigerant pipe that connects the above devices to form a refrigerant circuit, and 6 is provided in the evaporation side heat exchanger 4. The air path indicated by the arrow 6A is formed by the blower.
7 is provided on the suction side of the air passage of the evaporation side heat exchanger 4, and suction side dry bulb temperature detecting means for detecting the temperature on the suction side, and 8 is a blow side dry bulb temperature detecting means for detecting the temperature on the outlet side. , 9 is an evaporating temperature detecting means provided on the inflow side of the evaporating side heat exchanger 4 for detecting the evaporating temperature.
[0003]
FIG. 6 is a schematic air diagram showing changes in sensible heat ratio (SHF) in a conventional air conditioner. Here, as an example, design point A (suction, blown air with SHF = 1, air volume 300 m ³ / min, sensible heat capacity 56 kW under conditions of suction air temperature 24 ° C. (dry bulb temperature) and humidity (RH) 45% The state of the air at the inlet, the heat exchanger, and the outlet when the set humidity conditions are different from the heat exchanger and the blower specification designed in the above are shown.
The blowing temperature at 100% load (load 56 kW) at the design point A can be obtained by obtaining ΔT from the sensible heat ratio (SHF) = 1 according to the following equation.
Q = 60 × Va × Cp / v × ΔT / 860 (1)
Q: Sensible heat capacity (kW)
Va: Air volume (m ³ / min)
Cp: Specific heat of air (kcal / kg · ° C)
v: Specific volume of air (m ³ / kg)
ΔT: Dry bulb temperature difference (° C) between suction side and outlet side
[0004]
Here, for the sake of simplicity, ΔT is calculated with Cp = 0.24 and v = 0.85 in equation (1), and the blowout temperature is calculated to be 14.5 ° C. as shown in FIG. It becomes. The dew point temperature at this time is obtained as an intersection of the same absolute humidity line B of SHF = 1 passing through the design point A at the intake air temperature of 24 ° C. and the saturation curve from the fact that SHF = 1 and the wet air diagram, and 11 ° C. It becomes. If this dew point temperature is controlled as the target evaporation temperature, the sensible heat capacity can be satisfied without dehumidification. Conventionally, the dew point temperature + α at a certain design point is set as a target evaporation temperature, and the target evaporation temperature is generally adjusted based on the difference (load) between the suction temperature set value and the suction temperature.
[0005]
[Problems to be solved by the invention]
Since the conventional air conditioner is configured as described above, when the suction state is slightly higher than the design point A in FIG. 6, for example, when the humidity (RH) is 50%, the load is 100% (load 56 kW). The blowout temperature is calculated as 14.5 ° C. from the equation (1) as in the case of 45% humidity (RH). The dew point at this time is the intake air temperature of 24 ° C. and 50% RH in FIG. Is obtained as the intersection of the same absolute humidity line D of SHF = 1 passing through the intersection C and the saturation curve and becomes 13 ° C., and the difference between the blowing temperature and the dew point temperature becomes small. That is, the target evaporation temperature is set without knowing the humidity state of the intake air, and control is performed by setting the target evaporation temperature to 11 ° C. as in the above 45% RH only by the suction side dry bulb temperature information. And the part corresponding to the humidity of 5% will be dehumidified. Especially when pulling down (at 50% RH or higher), dehumidification becomes significant, and excessive dehumidification is performed. As a result, the design condition is significantly lower than 45% RH, and static electricity is generated in a low humidity environment. There has been a problem that there is a possibility of adverse effects on computers such as computers.
[0006]
In addition, as a conventional high sensible heat control method, for example, as shown in Japanese Examined Patent Publication No. 7-92259, a dew condensation water detection means is provided, and this means that dew condensation water (dehumidified drain water) is detected (dehumidified). In some cases, the target evaporating temperature is raised when the detection is performed. However, this method is an evaporating temperature control that does not generate condensed water under high load and high humidity conditions. There was a problem that there was a possibility that it could not be put out.
Conventionally, as a backup in case of such a low humidity condition, humidification is performed by detecting a low humidity condition and humidifying is performed, but in this case, the amount of humidification and humidification capacity are increased. was there.
In addition, when the air condition around a computer such as a computer is not matched with the evaporation temperature control of the evaporation side heat exchanger, the operation becomes inefficient and the power consumption increases.
[0007]
The present invention has been made to solve the above-described problems, and is provided with humidity detection means in the evaporation side heat exchanger to detect the humidity on the suction side and to detect the dew point temperature with respect to the intake air. Accordingly, an object of the present invention is to provide an air conditioner that can perform high sensible heat control according to a load without excessively dehumidifying, and can minimize the amount of dehumidification, and a control method thereof.
[0009]
[Means for Solving the Problems]
The air conditioner according to the present invention also includes a variable capacity compressor, a condensation side heat exchanger that condenses and liquefies the gas refrigerant discharged from the compressor, and a liquefied refrigerant from the condensation side heat exchanger. A squeezing device for depressurization, an evaporation side heat exchanger for evaporating and gasifying the refrigerant depressurized by the squeezing device, a dry bulb temperature detecting means for detecting the temperature on the suction side or the outlet side of the evaporation side heat exchanger, Humidity detection means for detecting the humidity on the suction side of the evaporation side heat exchanger, evaporation temperature detection means for detecting the evaporation temperature of the evaporation side heat exchanger, and a control device for controlling the evaporation temperature to be higher than the dew point temperature , The target evaporation temperature is set to the dew point temperature, and the controller is operated every predetermined time so that the evaporation temperature during operation falls within a predetermined range including the target evaporation temperature. Exceeding the upper limit of the predetermined range When increasing the capacity of the compressor, the throttle flow rate of the throttle device is increased. When the lower limit of the predetermined range is exceeded, the compressor capacity is reduced and the throttle flow rate of the throttle device is reduced. It is what I did .
[0010]
The air conditioner according to the present invention is also provided with a dew point temperature matrix corresponding to the intersection of the suction side dry bulb temperature and humidity with the same absolute humidity line and saturation curve in the wet air diagram, and this dew point temperature matrix. The dew point temperature is obtained from
[0011]
In the air conditioning apparatus according to the present invention, the cooling air blown out from the evaporation side heat exchanger is subjected to a load such as a computer through the inside of the double floor of the chamber in which the evaporation side heat exchanger is installed. It is intended to be supplied to a stored rack.
[0013]
The control method of the air conditioner according to the present invention also sets a target temperature of the suction temperature or the blowout temperature, and controls the suction temperature or the blowout temperature during operation to be within a predetermined range including the target temperature. When the suction temperature or blowing temperature during operation exceeds the upper limit of the predetermined range, the target evaporation temperature is lowered within the range not lower than the dew point temperature, and exceeds the lower limit of the predetermined range. In this case, the target evaporation temperature is increased.
[0014]
The control method for the air conditioner according to the present invention also sets the target humidity and sets the control device at predetermined time intervals so that the suction side humidity of the evaporation side heat exchanger is within a predetermined range including the target humidity. When the suction side humidity exceeds the upper limit of the predetermined range, the target evaporation temperature is lowered within the range not lower than the dew point temperature, and when the lower limit of the predetermined range is exceeded, the target evaporation temperature is increased. It is what I did.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a refrigerant circuit diagram showing the configuration of the first embodiment. In this figure, 1 is a variable capacity compressor, 2 is a condensation side heat exchanger for condensing and liquefying the gas refrigerant discharged from the compressor 1, and 3 is a flow rate for reducing the pressure of the liquefied refrigerant from the condensation side heat exchanger 2. A variable expansion device, 4 is an evaporation side heat exchanger that evaporates the decompressed refrigerant, 5 is a refrigerant pipe that connects the above devices to form a refrigerant circuit, and 6 is provided in the evaporation side heat exchanger 4. The air path indicated by the arrow 6A is formed by the blower. 7 is provided on the suction side of the air passage of the evaporation side heat exchanger 4, and suction side dry bulb temperature detecting means for detecting the temperature on the suction side, and 8 is a blow side dry bulb temperature detecting means for detecting the temperature on the outlet side. , 9 is provided on the inflow side of the evaporation side heat exchanger 4, evaporating temperature detecting means for detecting the evaporating temperature, 10 is humidity detecting means provided on the suction side of the evaporation side heat exchanger 4, and 11 is dry on the suction side. Capacitance control means for controlling the capacity of the compressor based on the detection values of the bulb temperature detection means 7 or the blow-off dry bulb temperature detection means 8, the evaporation temperature detection means 9 and the humidity detection means 10, and 12 is the detection of the evaporation temperature detection means 9. This is a flow rate control means for controlling the refrigerant flow rate of the expansion device 3 based on the value.
[0016]
FIG. 2 is a schematic diagram showing a state in which the air conditioner of Embodiment 1 is installed in the computer room. In this figure, 20 is a computer room, and 21 is a double floor forming a free-access floor, and the inside is a passage for cooling air blown out from an indoor unit to be described later. Reference numeral 22 denotes an indoor unit of an air conditioner that houses the evaporation side heat exchanger 4, the expansion device 3, the blower 6, the suction side and blowout side dry bulb temperature detection means 7, 8, the humidity detection means 10, the flow rate control means 12, and the like. At the same time, the computer room air is sucked from the upper suction port 23, and the cooling air is blown out from the lower air outlet 24 to the inside of the floor surface 21. In this embodiment, the upper part is the inlet 23 and the lower part is the outlet 24. However, the lower outlet 24 may be the inlet and the upper inlet 23 may be the outlet by reversing this configuration. it can.
[0017]
Further, in this embodiment, in order to reduce the installation area of the indoor unit, a configuration based on a split system in which refrigerant circuit components such as a compressor and an accumulator are accommodated in an outdoor unit (not shown) is shown. It is also possible to adopt a remote system in which each refrigerant circuit component is accommodated in an indoor unit.
Reference numeral 25 denotes a rack that accommodates computer equipment, and its lower surface communicates with the inside of the double floor 21.
[0018]
In such a configuration, the cooling air blown from the air outlet 24 of the indoor unit 22 passes through the inside of the free-access floor surface 21 as indicated by an arrow 6A, and a rack in which computer equipment as a load is stored. The air that has been sucked into 25 and has finished cooling the computer equipment is discharged upward from the rack 25 into the computer room 20 and sucked into the suction port 23 of the indoor unit 22. In the indoor unit 22, the evaporation temperature of the evaporation side heat exchanger 4 is detected by the evaporation temperature detecting means 9, and the compressor capacity and the refrigerant flow rate of the expansion device are controlled so that this temperature becomes equal to or higher than the dew point temperature.
[0019]
FIG. 3 is a block diagram showing a procedure of dew point temperature detection in the first embodiment.
As shown in FIG. 3 (A), the suction-side dry bulb temperature detected by the suction-side dry bulb temperature detecting means 7 and the humidity detected by the humidity detecting means 10 (here, the relative humidity is explained, but absolute humidity may be used). From the above, the intersection of the dry bulb temperature and the humidity curve on the wet air diagram illustrated in FIG. 6 is obtained, and the sensible heat ratio (SHF) = 1 passing through this intersection, that is, the intersection of the same absolute humidity line and the saturation curve To determine the dew point temperature. In this case, as shown in FIG. 3B, a dew point temperature matrix in which the vertical axis represents the suction-side dry bulb temperature, the horizontal axis represents humidity, and the dew point temperature obtained as described above is displayed at the intersection point in advance. By preparing, if the dry bulb temperature and humidity are known, the dew point temperature can be easily obtained.
The dew-point temperature matrix has a dry bulb temperature interval of 1 ° C. and a humidity interval of 5% . Interpolation approximation is used for each intermediate value, and extrapolation approximation is used outside the matrix range.
[0020]
Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to the drawings. Since the refrigerant circuit diagram and temperature / humidity detection means of this embodiment are the same as those in FIG. 1, the explanation is omitted by using FIG. 1, and the control method of the second embodiment is based on the flowchart of FIG. Will be described.
[0021]
First, in step S1, a target humidity RHm and a target suction temperature or blowing temperature TLm are set. Next, the dew point temperature TR is obtained by the procedure described in the first embodiment from the target humidity RHm and the suction temperature Tin detected by the suction side dry bulb temperature detection means 7 in step S2. Next, in step S3, the initial setting value Tem0 of the target evaporation temperature is set as Tem0 = TR. In step S4, Tem0−ΔTe ≦ Te ≦ Tem0 + ΔTe at a temperature difference ΔTe set in advance with respect to the evaporation temperature Te. Thus, the evaporation temperature Te is controlled at every set elapsed time. If the evaporation temperature Te exceeds the above range, a check is made in step S5. If Tem0 + ΔTe <Te, the compressor capacity F is increased by the capacity control means 11 of the compressor in step S6 and the expansion device 3 The throttle flow rate L is increased by the flow rate control means 12. On the other hand, if Tem0−ΔTe> Te, the compressor capacity F is reduced by the compressor capacity control means 11 and the throttle flow rate L is reduced by the flow control means 12 of the expansion device 3 in step S7.
[0022]
In step S8, it is determined whether or not the current suction temperature or the blowing temperature TL has approached the target set temperature TLm at every set elapsed time. If not, the target evaporation temperature Tem is changed. That is, if not approaching, it is checked in step S9, and if TLm0 + ΔTL <TL at a temperature difference ΔTL set in advance with respect to the suction temperature or the blow-out temperature TL, the target evaporation temperature Tem is set in step S10. Bring it down. However, Te ≧ TR at this time.
On the other hand, if TLm0−ΔTL> TL, the target evaporation temperature Tem is increased in step S11. If the suction temperature or the blowout temperature TL has approached the target set temperature TLm, it is determined in step S12 whether the current humidity RH has approached the target humidity RHm. If it has approached, the target in step S16. The evaporating temperature Tem, the compressor capacity F, and the flow rate L of the throttle device are left as they are. If they are not approaching, the target evaporating temperature Tem is changed. That is, if not approaching, it is checked in step S13, and if RHm + ΔRH <RH with a humidity difference ΔRH set in advance with respect to the humidity RH, the target evaporation temperature Tem is lowered in step S14. However, Te ≧ TR at this time. On the other hand, if RHm−ΔRH> RH, the target evaporation temperature Tem is increased in step S15.
[0023]
By performing such control, the dehumidification amount can be suppressed without the temperature falling below the dew point temperature while satisfying the required load capacity with respect to the set temperature TLm of the suction or blowing temperature.
[0025]
【The invention's effect】
The air conditioner according to the present invention also includes a variable capacity compressor, a condensation side heat exchanger that condenses and liquefies the gas refrigerant discharged from the compressor, and a liquefied refrigerant from the condensation side heat exchanger. A squeezing device for depressurization, an evaporation side heat exchanger for evaporating and gasifying the refrigerant depressurized by the squeezing device, a dry bulb temperature detecting means for detecting the temperature on the suction side or the outlet side of the evaporation side heat exchanger, Humidity detection means for detecting the humidity on the suction side of the evaporation side heat exchanger, evaporation temperature detection means for detecting the evaporation temperature of the evaporation side heat exchanger, and a control device for controlling the evaporation temperature to be higher than the dew point temperature , The target evaporation temperature is set to the dew point temperature, and the controller is operated every predetermined time so that the evaporation temperature during operation falls within a predetermined range including the target evaporation temperature. Exceeding the upper limit of the predetermined range When increasing the capacity of the compressor, the throttle flow rate of the throttle device is increased. When the lower limit of the predetermined range is exceeded, the compressor capacity is reduced and the throttle flow rate of the throttle device is reduced. since as it is obtained by, in the case where the actual operating environment, such as a pull-down time is shifted from the design point also, in addition to high sensible heat operation is possible, the evaporation temperature while satisfying the required load capacity of the dew-point temperature The dehumidification amount can be suppressed without lowering.
[0026]
The air conditioner according to the present invention is also provided with a dew point temperature matrix corresponding to the intersection of the suction side dry bulb temperature and humidity with the same absolute humidity line and saturation curve in the wet air diagram, and this dew point temperature matrix. Since the dew point temperature is obtained from the dew point temperature, the dew point temperature can be easily obtained and accurate control is possible.
[0027]
In the air conditioning apparatus according to the present invention, the cooling air blown out from the evaporation side heat exchanger is subjected to a load such as a computer through the inside of the double floor of the chamber in which the evaporation side heat exchanger is installed. Since it is supplied to the stored rack, air conditioning in the computer room can be performed easily and accurately.
[0029]
The control method of the air conditioner according to the present invention also sets a target temperature of the suction temperature or the blowout temperature, and controls the suction temperature or the blowout temperature during operation to be within a predetermined range including the target temperature. When the suction temperature or blowing temperature during operation exceeds the upper limit of the predetermined range, the target evaporation temperature is lowered within the range not lower than the dew point temperature, and exceeds the lower limit of the predetermined range. In this case, since the target evaporation temperature is increased, high sensible heat operation with high efficiency and low dehumidification amount can be performed.
[0030]
The control method for the air conditioner according to the present invention also sets the target humidity and sets the control device at predetermined time intervals so that the suction side humidity of the evaporation side heat exchanger is within a predetermined range including the target humidity. When the suction side humidity exceeds the upper limit of the predetermined range, the target evaporation temperature is lowered within the range not lower than the dew point temperature, and when the lower limit of the predetermined range is exceeded, the target evaporation temperature is increased. As a result, the dehumidification amount can be suppressed without the evaporation temperature falling below the dew point temperature while satisfying the required load capacity.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram showing the configuration of Embodiment 1 of the present invention.
FIG. 2 is a schematic diagram showing a state where the air conditioner of Embodiment 1 is installed in a computer room.
FIG. 3 is a block diagram showing a procedure for dew point temperature detection in the first embodiment.
FIG. 4 is a high sensible heat control flowchart showing a control method according to Embodiment 2 of the present invention;
FIG. 5 is a refrigerant circuit diagram showing a configuration of a conventional air conditioner.
FIG. 6 is a schematic air diagram showing SHF change in a conventional air conditioner.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condensation side heat exchanger, 3 Throttling device, 4 Evaporation side heat exchanger, 5 Refrigerant piping, 6 Blower, 6A Air path, 7 Suction side dry bulb temperature detection means, 8 Outlet side dry bulb temperature detection means 9 Evaporation temperature detection means, 10 Humidity detection means, 11 Capacity control means, 12 Flow rate control means, 20 Computer room, 21 Double floor, 22 Indoor unit, 23 Suction port, 24 Outlet, 25 Racks.

Claims (5)

Variable capacity compressor, condensing side heat exchanger for condensing and liquefying gas refrigerant discharged from the compressor, throttling device for decompressing the liquefied refrigerant from the condensing side heat exchanger, and decompression by the throttling device An evaporation side heat exchanger for evaporating the generated refrigerant, dry bulb temperature detecting means for detecting the temperature on the suction side or the outlet side of the evaporation side heat exchanger, and the humidity on the suction side of the evaporation side heat exchanger Humidity detecting means for detecting the evaporating temperature, evaporating temperature detecting means for detecting the evaporating temperature of the evaporating side heat exchanger, and a control device for controlling the evaporating temperature to be equal to or higher than the dew point temperature, and setting the target evaporating temperature to the dew point temperature. In addition, the control device is operated every predetermined time so that the evaporation temperature during operation falls within a predetermined range including the target evaporation temperature, and the evaporation temperature during operation exceeds the upper limit of the predetermined range. When the compressor capacity is increased Air while, to increase the aperture flow throttling device, when exceeding the lower limit of the predetermined range, the capacity of the compressor as well as small, is characterized in that so as to reduce the aperture flow throttling device Harmony device.   A dew point temperature matrix is provided that correlates the intersection of the suction side dry bulb temperature and humidity with the same absolute humidity line and saturation curve in the wet air diagram, and the dew point temperature matrix is obtained from this dew point temperature matrix. The air conditioner according to claim 1, wherein   The cooling air blown from the evaporation side heat exchanger is supplied to a rack in which a load such as a computer is stored via the inside of the double floor of the room where the evaporation side heat exchanger is installed. The air conditioner according to claim 1 or 2, wherein the air conditioner is configured as described above. The air conditioning apparatus according to any one of claims 1 to 3, wherein a target temperature of the suction temperature or the blowout temperature is set, and the suction temperature or the blowout temperature during operation is within a predetermined range including the target temperature. The control device is operated every predetermined time so that the target evaporation temperature is lowered within a range that does not fall below the dew point temperature when the suction temperature or the blowing temperature during operation exceeds the upper limit of the predetermined range. when it exceeds the lower limit of the predetermined range, the control method of the air conditioner being characterized in that so as to increase the target evaporation temperature. The target humidity is set, and the controller is operated every predetermined time so that the suction side humidity of the evaporation side heat exchanger is within a predetermined range including the target humidity, and the suction side humidity is within the predetermined range. The target evaporation temperature is lowered within a range that does not fall below the dew point temperature when the upper limit is exceeded, and the target evaporation temperature is increased when the lower limit of the predetermined range is exceeded. The control method of the air conditioning apparatus of 4 .

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