WO2018221652A1

WO2018221652A1 - Air conditioning apparatus

Info

Publication number: WO2018221652A1
Application number: PCT/JP2018/020954
Authority: WO
Inventors: 明敏上野; 駒野　宏; 隆司武内; 祥吾馬渕
Original assignee: ダイキン工業株式会社
Priority date: 2017-05-31
Filing date: 2018-05-31
Publication date: 2018-12-06

Abstract

Provided is an air conditioning apparatus capable of appropriately controlling the superheating degree of a refrigerant passing through an evaporator by controlling the opening degree of a cooling expansion valve. The air conditioning apparatus is provided with a compressor (12), an outdoor condenser (13), a cooling expansion valve (14), an evaporator (15), a cooling circuit (11) that connects the foregoing components in that order, a reheating path (21), an indoor condenser (22), a reheating expansion valve (23), and a control device (30). The control device (30) is provided with: a cooling control unit (31) for regulating the amount of a refrigerant circulating in the evaporator (15) by controlling the opening degree of the cooling expansion valve (14), thereby regulating the superheating degree of the refrigerant that passes through the evaporator (15); and a reheating control unit (32) for regulating the amount of a refrigerant circulating in the indoor condenser (22) by controlling the opening degree of the reheating expansion valve (23), thereby regulating the room temperature. In the reheating expansion valve (23), the upper limit of the opening degree controlled by the reheating control unit (32) is set on the basis of the ratio of the cooling capability in the evaporator (15), which enables the regulation of the superheating degree by the cooling expansion valve (14), to the reheating capability in the indoor condenser (22).

Description

Air conditioner

The present invention relates to an air conditioner capable of reheat dehumidification operation.

Conventionally, an air conditioner capable of performing a reheat dehumidification operation in which dehumidification is performed while suppressing a decrease in indoor temperature is known (for example, see Patent Documents 1 and 2). In this air conditioner, a compressor, an outdoor condenser, a cooling expansion valve, and an evaporator (cooler) are connected in this order by refrigerant piping. The refrigerant discharged from the compressor is condensed by the outdoor condenser, depressurized by the cooling expansion valve, and then evaporated by exchanging heat with the room air in the evaporator, thereby cooling and dehumidifying the room air.

The air conditioner includes a reheat path that bypasses the outdoor condenser and the cooling expansion valve, and an indoor condenser (reheater) and a reheat expansion valve are provided in the reheat path. . The refrigerant discharged from the compressor flows not only to the outdoor condenser but also to the indoor condenser, and is condensed by exchanging heat with indoor air that has passed through the evaporator in the indoor condenser. The pressure is reduced by the reheat expansion valve, merges with the refrigerant from the cooling expansion valve, and flows into the evaporator. The indoor condenser maintains indoors at a predetermined temperature by heating indoor air cooled and dehumidified in the evaporator.

JP 2011-133171 A JP-A-1-222137

In the air conditioner as described above, normally, a predetermined degree of superheat is given to the refrigerant that has passed through the evaporator, and the compressor is configured not to suck the liquid refrigerant. The degree of superheat is adjusted to a predetermined value by adjusting the flow rate of the refrigerant flowing through the evaporator by controlling the opening of the cooling expansion valve. On the other hand, the indoor temperature is adjusted to the target temperature by adjusting the flow rate of the refrigerant flowing through the indoor condenser by controlling the opening degree of the reheat expansion valve.

However, if the opening of the reheat expansion valve is increased in order to increase the reheat capacity, the flow rate of the refrigerant flowing into the evaporator through the indoor condenser with respect to the flow rate of the refrigerant flowing into the evaporator through the outdoor condenser Therefore, it becomes difficult to adjust the degree of superheat by controlling the opening degree of the cooling expansion valve.

This invention is made in view of such a situation, and provides the air conditioning apparatus which can control suitably the superheat degree of the refrigerant | coolant which passed the evaporator by the opening degree control of a cooling expansion valve. Objective.

(1) The air conditioner of the present invention
A compressor,
An outdoor condenser for condensing the refrigerant compressed by the compressor;
A cooling expansion valve for decompressing the refrigerant condensed in the outdoor condenser;
An evaporator for evaporating the refrigerant decompressed by the cooling expansion valve by heat exchange with room air to cool and dehumidify the room air;
A cooling circuit connecting the compressor, the outdoor condenser, the cooling expansion valve, and the evaporator in this order;
A reheat path branched from a path connecting the compressor and the outdoor condenser in the cooling circuit, and connected to a path connecting the cooling expansion valve and the evaporator;
An indoor condenser that heats the indoor air by condensing the refrigerant compressed by the compressor by heat exchange with indoor air cooled and dehumidified by the evaporator in the reheat path;
A reheat expansion valve for decompressing the refrigerant condensed in the indoor condenser in the reheat path;
A control device that controls the opening degree of the cooling expansion valve and the reheat expansion valve, and
The control device includes:
A cooling control unit that adjusts a refrigerant circulation amount in the evaporator and adjusts a degree of superheat of the refrigerant after passing through the evaporator by opening control of the cooling expansion valve;
A reheat control unit for adjusting a room temperature by adjusting a refrigerant circulation amount in the indoor condenser by controlling an opening degree of the reheat expansion valve;
The reheat expansion valve is controlled by the reheat control unit based on the ratio of the cooling capacity in the evaporator and the reheat capacity in the indoor condenser that enables adjustment of the degree of superheat by the cooling expansion valve. The upper limit of the opening is set.

The upper limit of the opening does not include the opening in the fully opened state, but means the opening between the fully closed state and the fully opened state of the rethermal expansion valve.
The air-conditioning apparatus having the above-described configuration enables the adjustment of the degree of superheat by the cooling expansion valve, based on the ratio of the cooling capacity in the evaporator and the reheating capacity in the indoor condenser. Since the upper limit is set, the refrigerant circulation rate of the indoor condenser can be limited so that the ratio of the refrigerant circulation rate of the indoor condenser to the refrigerant circulation rate of the evaporator does not become excessively large, and the cooling expansion valve is opened. It is possible to appropriately adjust the superheat degree of the evaporator by the degree control.

(2) Preferably, the said control apparatus is further provided with the upper limit adjustment part which adjusts the upper limit of the opening degree of the said reheat expansion valve according to the fluctuation | variation of the cooling capacity in the said evaporator in operation.
According to this configuration, for example, when the cooling capacity of the evaporator is reduced in accordance with a decrease in the external heat load during operation, the upper limit of the reheat expansion valve opening is adjusted to be low, Since the reheat capacity in the evaporator can also be reduced, even if fluctuations occur in the cooling capacity of the evaporator, the ratio of the refrigerant circulation rate in the indoor condenser to the refrigerant circulation rate in the evaporator does not become excessively large, It is possible to appropriately adjust the degree of superheat by controlling the opening degree of the cooling expansion valve.

(3) Preferably, the upper limit of the opening degree of the reheat expansion valve is adjusted based on a ratio between a refrigerant circulation amount flowing through the cooling expansion valve and a refrigerant circulation amount flowing through the reheat expansion valve.
According to this configuration, the refrigerant circulation amount that flows through the cooling expansion valve is correlated with the cooling capacity of the evaporator, and the refrigerant circulation amount that flows through the reheat expansion valve is correlated with the reheat capacity of the indoor condenser. The upper limit of the opening degree of the rethermal expansion valve can be adjusted based on the ratio between the refrigerant circulation amount flowing through the cooling expansion valve and the refrigerant circulation amount flowing through the reheat expansion valve.

(4) Preferably, the upper limit of the opening degree of the reheat expansion valve is based on a ratio between a temperature difference between air before and after passing through the evaporator and a temperature difference between air before and after passing through the indoor condenser. Adjusted.
According to this configuration, the temperature difference between the air before and after passing through the evaporator correlates with the cooling capacity in the evaporator, and the temperature difference between the air before and after passing through the indoor condenser is reheated in the indoor condenser. Correlates with ability. Therefore, the upper limit of the opening degree of the rethermal expansion valve can be adjusted based on the ratio of these temperature differences. Moreover, since each temperature difference can be easily measured using an air temperature sensor, an operation for adjusting the upper limit of the opening degree of the reheat expansion valve can be easily performed.

(5) Preferably, the said reheat control part correct | amends the control amount of the opening degree of the said reheat expansion valve according to the supercooling degree of the refrigerant | coolant of the exit of the said indoor condenser, and adjusts the said supercooling degree .
If the degree of supercooling at the outlet of the indoor condenser cannot be ensured sufficiently, the gas-liquid two-phase refrigerant will flow into the reheat expansion valve, the amount of refrigerant circulating to the indoor condenser will rapidly decrease, and the superheat degree control will be disturbed. Inconvenience arises.
In view of such inconvenience, in the air conditioner having the above configuration, the reheat control unit corrects the control amount of the opening degree of the reheat expansion valve according to the degree of supercooling of the refrigerant at the outlet of the indoor condenser, Since the degree of supercooling is adjusted to a predetermined value, the degree of supercooling can be suitably secured.

(6) Preferably, the control device performs operation control in a reheat dehumidification mode in which the air cooled and dehumidified by the evaporator is heated by the indoor condenser, and the air cooled and dehumidified by the evaporator is condensed by the indoor condenser. The reheat dehumidification is performed when the intake air temperature of the evaporator is within a target temperature range and the relative humidity of the intake air is equal to or higher than the target humidity. When the mode is operated, the suction air temperature of the evaporator is higher than the target temperature, or when the suction air temperature is within the target temperature range and the relative humidity of the suction air is lower than the target humidity, It is configured to drive.

According to this configuration, when the intake air temperature of the evaporator is within the target temperature range and the relative humidity of the intake air is equal to or higher than the target humidity, the humidity is relatively high with respect to the temperature of the indoor space. The operation in the reheat dehumidification mode is performed so as to lower the humidity without lowering the temperature. Also, when the intake air temperature of the evaporator is higher than the target temperature, or when the intake air temperature is within the target temperature range and the relative humidity of the intake air is less than the target humidity, the temperature is prioritized over the humidity. The operation in the cooling mode is performed so as to lower. Thus, the reheat dehumidification mode and the cooling mode are performed according to the state of the intake air, and the humidity and temperature of the indoor space are controlled to appropriate values.

(7) Preferably, a reheat first on-off valve is connected to the refrigerant reflow refrigerant pipe on the refrigerant inflow side of the indoor condenser during operation in the reheat dehumidification mode, and the refrigerant outlet side of the indoor condenser is connected to the refrigerant outflow side. The reheat expansion valve is connected;
The reheating refrigerant pipe is connected to a reheating bypass pipe that bypasses the first reheating opening / closing valve, and the reheating bypass pipe has a smaller diameter than the first reheating opening / closing valve. A second heat on-off valve is connected.

(8) Preferably, when the control device starts operation in the reheat dehumidification mode, the control device opens the reheat expansion valve in a state where the first reheat opening / closing valve is closed. The second on-off valve for reheating is opened after a time, and the liquid refrigerant removing operation is performed to open the first on-off valve for reheating after a predetermined time.
According to this configuration, when the operation in the reheat dehumidification mode is started, the reheat second on-off valve having a smaller diameter than the first reheat first on-off valve is opened first, thereby reheating during the cooling operation. Since the liquid refrigerant accumulated in the refrigerant piping does not pass through the reheating expansion valve at once, vibration and noise of the piping can be prevented.

(9) Preferably, when the control device ends the operation in the reheat dehumidification mode, the reheat is started after a predetermined time from closing the first reheat on-off valve and the second reheat on-off valve. The thermal expansion valve is configured to be closed.
According to this configuration, when the operation of the reheat dehumidification mode is finished, the reheat expansion valve is closed after a predetermined time after the first reheat valve and the second reheat valve are closed. In the meantime, the liquid refrigerant in the indoor condenser can be discharged from the indoor condenser. The liquid refrigerant flowing out of the indoor condenser can be recovered by the compressor after being evaporated by the evaporator of the cooling circuit.

According to the present invention, the degree of superheat of the refrigerant that has passed through the evaporator can be suitably controlled by controlling the opening of the cooling expansion valve.

It is a schematic structure figure showing the air harmony device concerning a 1st embodiment of the present invention. It is a block diagram which shows the function of a control apparatus. It is a flowchart which shows the procedure of the basic control of an air conditioning apparatus. It is explanatory drawing which shows the relationship between the cooling capacity and the reheat capacity accompanying the change of an external load. It is a flowchart which shows the procedure of the application control 1 of an air conditioning apparatus. It is a flowchart which shows the procedure of the application control 2 of an air conditioning apparatus. It is a flowchart which shows the procedure of the application control 2 of an air conditioning apparatus. It is the figure which represented the refrigerating cycle on the Mollier diagram. It is a schematic block diagram which shows the air conditioning apparatus which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the state which switches an operation mode according to a chamber (indoor) temperature. It is a flowchart which shows operation mode switching control. It is a table | surface which shows the setting state of the component apparatus of the refrigerant circuit in each operation mode. It is a time chart which shows the opening / closing timing of the 1st on-off valve for reheating, and the 2nd on-off valve for reheating.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
<Overall configuration of air conditioner>
FIG. 1 is a schematic configuration diagram showing an air conditioner according to an embodiment of the present invention.
The air conditioner 1 according to the present embodiment is used in an environment in which a cooling target such as meat containing a lot of moisture frequently enters and exits a room, such as a meat factory, and dehumidifies while keeping the room temperature constant. It is the air conditioning apparatus 1 which can perform the reheat dehumidification operation which also performs. For example, the air conditioner 1 is a refrigeration apparatus that is used to cool a space to be cooled, such as a meat shed in a meat processing factory.

The air conditioner 1 includes an outdoor unit (heat source unit) 2 and an indoor unit (use unit) 3, and the outdoor unit 2 and the indoor unit 3 are connected by a refrigerant communication pipe. The air conditioner 1 includes a control device 30 that controls the operations of the outdoor unit 2 and the indoor unit 3.

The outdoor unit 2 is installed outdoors, for example, and includes a compressor 12, an outdoor condenser 13, an outdoor fan 16, a refrigerant pressure sensor Sc2, and the like.
The indoor unit 3 is disposed indoors in a factory, for example, and includes a first expansion valve 14, an evaporator (cooler) 15, an indoor condenser (reheater) 22, a second expansion valve 23, and an indoor fan. 17, air temperature sensors Sa1, Sa2, Sa3, refrigerant temperature sensors Sb1, Sb2, Sb3, Sb4, Sb5, a refrigerant pressure sensor Sc1, and the like.

The compressor 12, the outdoor condenser 13, the first expansion valve 14, and the evaporator 15 form a cooling circuit 11 by being connected by a refrigerant pipe in this order. The cooling circuit 11 functions exclusively to reduce the temperature and humidity of room air.
Moreover, the air conditioning apparatus 1 of this embodiment branches from the path | route 11a which connects the compressor 12 and the outdoor condenser 13 in the cooling circuit 11, and the path | route 11b which connects the 1st expansion valve 14 and the evaporator 15 in it. Is provided with a reheat path 21 connected to the. The reheat path 21 bypasses the outdoor condenser 13 and the first expansion valve 14 in the cooling circuit 11. The reheat path 21 is provided with an indoor condenser 22 and a second expansion valve 23. Therefore, the indoor condenser 22 and the second expansion valve 23 are provided in parallel with the outdoor condenser 13 and the first expansion valve 14. The reheat path 21 functions to increase the temperature of the indoor air cooled by the cooling circuit 11.

The compressor 12 is, for example, a variable capacity type driven by a motor whose operating frequency (operation speed) can be adjusted by inverter control or the like. The compressor 12 compresses the low-temperature / low-pressure gaseous refrigerant sent from the evaporator 15 into a high-temperature / high-pressure gaseous refrigerant. The compressor 12 may be of a fixed capacity type.

As the outdoor condenser 13, for example, a cross fin type fin-and-tube heat exchanger, a microchannel heat exchanger, or the like is used. The outdoor condenser 13 condenses the gaseous refrigerant discharged from the compressor 12 by exchanging heat with outdoor air to form a liquid refrigerant. The outdoor air is supplied to the outdoor condenser 13 by driving the outdoor fan 16.

The first expansion valve 14 is, for example, a pulse motor drive type electronic expansion valve, and the opening degree can be freely adjusted. The opening degree of the first expansion valve 14 is controlled by the control device 30. The first expansion valve 14 depressurizes the liquid refrigerant condensed by the outdoor condenser 13 to form a low-temperature / low-pressure gas-liquid two-phase refrigerant. Further, the first expansion valve 14 adjusts the flow rate of the refrigerant flowing through the evaporator 15 by controlling the opening degree, and adjusts the degree of superheat of the refrigerant after passing through the evaporator 15. In the following description, the first expansion valve 14 is also referred to as a “cooling expansion valve”.

As the evaporator 15, for example, a cross fin type fin-and-tube heat exchanger, a microchannel heat exchanger, or the like is used similarly to the outdoor condenser 13. The evaporator 15 evaporates the low-temperature and low-pressure gas-liquid two-phase refrigerant that has passed through the cooling expansion valve 14 by exchanging heat with the room air to form a gaseous refrigerant. Further, the evaporator 15 functions as a cooler that cools and dehumidifies indoor air by heat exchange with the refrigerant. The indoor air is supplied to the evaporator 15 by driving the indoor fan 17.

As the outdoor condenser 13, for example, a cross fin type fin-and-tube heat exchanger, a microchannel heat exchanger, or the like is adopted as the indoor condenser 22. The indoor condenser 22 is supplied with indoor air cooled and dehumidified by the evaporator 15 by driving the indoor fan 17. Moreover, the indoor condenser 22 branches inflow from the path | route 11a which the gaseous refrigerant discharged from the compressor 12 flows into the outdoor condenser 13, and heat-exchanges this gaseous refrigerant with indoor air. To condense. Thereby, the indoor air cooled and dehumidified by the evaporator 15 is heated with the humidity lowered, and blown out into the room. Therefore, the indoor condenser 22 functions as a reheater that reheats the indoor air cooled by the evaporator 15.

The second expansion valve 23 is a pulse motor drive type electronic expansion valve, for example, similar to the cooling expansion valve 14, and the opening degree can be freely adjusted. The opening degree of the second expansion valve 23 is controlled by the control device 30. The second expansion valve 23 depressurizes the liquid refrigerant condensed by the indoor condenser 22 to form a low-temperature / low-pressure gas-liquid two-phase refrigerant. Further, the second expansion valve 23 adjusts the flow rate of the refrigerant flowing through the indoor condenser 22 by controlling the opening degree, thereby adjusting the heating amount (reheat amount) of the indoor air. Hereinafter, the second expansion valve 23 is also referred to as a “reheat expansion valve”.

The air temperature sensors Sa1, Sa2, and Sa3 include a first air temperature sensor Sa1 that detects the temperature of air sucked into the indoor unit 3, and a second air temperature sensor Sa2 that detects the temperature of air blown from the indoor unit 3. And a third air temperature sensor Sa3 that detects the temperature of the air before passing through the evaporator 15 and being supplied to the indoor condenser 22.

The refrigerant temperature sensors Sb1, Sb2, Sb3, Sb4, and Sb5 are a first refrigerant temperature sensor Sb1 that detects the temperature of the refrigerant at the outlet of the evaporator 15, and a second refrigerant that detects the temperature of the refrigerant flowing through the evaporator 15. A temperature sensor Sb2, a third refrigerant temperature sensor Sb3 that detects the temperature of the refrigerant at the outlet of the indoor condenser 22 (before the reheat expansion valve 23), and a fourth refrigerant that detects the temperature of the refrigerant at the inlet of the indoor condenser 22. Temperature sensor Sb4 and 5th refrigerant | coolant temperature sensor Sb5 which detects the temperature of the refrigerant | coolant which is flowing through the indoor condenser 22 are included.

The refrigerant pressure sensors Sc1 and Sc2 are a first pressure sensor Sc1 that detects the refrigerant pressure at the outlet of the indoor condenser 22 (before the reheat expansion valve 23), and a second pressure sensor Sc2 that detects the discharge pressure of the compressor 12. Including.
The detection signals of the above sensors are input to the control device 30 and used for controlling various devices by the control device 30. In addition, the air conditioning apparatus 1 does not need to be provided with all the sensors demonstrated above, and should just be provided with the sensor used in the control example mentioned later at least.

The control device 30 is configured by an indoor control unit provided in the indoor unit 3, an outdoor control unit provided in the outdoor unit 2, and the like (both not shown). The control device 30 includes a microcomputer, a memory, a communication interface, and the like, and receives signals from various sensors provided in the indoor unit 3 and the outdoor unit 2. The control device 30 controls operations of the compressor 12, the

expansion valves

14 and 23, the

fans

16 and 17, and the like. The control device 30 can accept input of a target value (set temperature) of the suction temperature or the blowing temperature in the indoor unit 3 via a remote controller or the like connected to the indoor unit 3.

FIG. 2 is a configuration diagram illustrating functions of the control device 30.
The control device 30 has functions as a cooling control unit 31, a reheat control unit 32, and an upper limit adjustment unit 33.
The cooling control unit 31 adjusts the refrigerant circulation amount in the evaporator 15 by controlling the opening degree of the cooling expansion valve 14, and cools and dehumidifies the indoor air as desired by the cooling capacity in the evaporator 15, and the evaporator 15 It is a function part for adjusting the superheat degree of the refrigerant | coolant which passed through.

The reheat control unit 32 adjusts the refrigerant circulation amount in the indoor condenser 22 by controlling the opening degree of the reheat expansion valve 23, and adjusts the indoor temperature as desired by the reheat capability in the indoor condenser 22. Part. Moreover, the reheat control part 32 adjusts the opening degree of the reheat expansion valve 23 by making predetermined opening degree into an upper limit. The upper limit of the opening degree is an opening degree that is larger than the opening degree at which the rethermal expansion valve 23 is fully closed and smaller than the opening degree at which the reheating expansion valve 23 is fully opened.

Further, the upper limit adjustment unit 33 is a functional unit that adjusts the upper limit of the opening degree of the reheat expansion valve 23 by the reheat control unit 32. The upper limit adjustment unit 33 is a functional unit used exclusively in the application control 1 in the control examples described below.

In general, the cooling capacity φ _C can be expressed by the following formula (1), and the reheating capacity φ _R can be expressed by the following formula (2).

Here, CV _C and CV _R is the flow rate coefficient for the opening of the cooling expansion valve 14 and the reheat expansion valve 23, Delta] Pc is height differential pressure in the outdoor condenser 13 and evaporator 15, the [Delta] P _R, the indoor condenser 22 and the difference in pressure in the evaporator 15, h _C is the low-pressure enthalpy difference at the inlet / outlet of the evaporator 15 (see FIG. 8), and h _R is the high-pressure enthalpy difference at the inlet / outlet of the indoor condenser 22 (see FIG. 8). _), G C, the _{G R} is the specific gravity ratio of the high-pressure side refrigerant (water basis). The cooling system circulation amount indicates the circulation amount of the refrigerant that passes through the cooling expansion valve 14, and the reheat system circulation amount indicates the circulation amount of the refrigerant that passes through the reheat expansion valve 23. Therefore, the cooling capacity φ _C is obtained from the refrigerant circulation amount that passes through both the cooling expansion valve 14 and the reheat expansion valve 23 and flows into the evaporator 15. On the other hand, the reheat capability phi _R is determined from the circulation amount of refrigerant passing through the reheat expansion valve 23 through the indoor condenser 22.

[Control example of air conditioner]
As described above, the air conditioner 1 adjusts the refrigerant circulation amount in the evaporator 15 by controlling the opening degree of the cooling expansion valve 14, and adjusts the degree of superheat after passing through the evaporator 15 to a predetermined value. Thereby, a liquid refrigerant does not flow into the compressor 12, and the compressor 12 is protected.
On the other hand, not only the refrigerant that has passed through the cooling expansion valve 14 but also the refrigerant from the reheat path 21 flows into the evaporator 15. Since the circulation amount of the refrigerant flowing in from the reheat path 21 cannot be controlled by the cooling expansion valve 14, the superheat degree is adjusted by the cooling expansion valve 14 when the refrigerant circulation amount from the reheat path 21 is relatively increased. It becomes difficult.

Therefore, in the air conditioning apparatus 1 of the present embodiment, by setting an “upper limit” to the opening degree of the reheat expansion valve 23, the amount of refrigerant flowing into the evaporator 15 from the reheat path 21 is limited, and the cooling expansion valve 14, the degree of superheat can be adjusted. In other words, the upper limit of the opening degree of the reheat expansion valve 23 is set to a predetermined value within a range in which the degree of superheat by the cooling expansion valve 14 can be adjusted.

Hereinafter, a control example of the cooling expansion valve 14 and the reheat expansion valve 23 by the control device 30 will be described. Specifically, the most basic control (basic control) and its application (application control 1, 2) will be described in order.
<Basic control>
FIG. 3 is a flowchart showing a basic control procedure of the air conditioner. This basic control is a control example when the upper limit of the opening degree of the reheat expansion valve 23 is fixed.
First, in step S1, the refrigerant temperature Tco at the outlet of the evaporator 15 is detected by the first refrigerant temperature sensor Sb1. In step S2, the temperature Tcm of the refrigerant flowing through the evaporator 15 is detected by the second refrigerant temperature sensor Sb2. The refrigerant temperature Tcm corresponds to the evaporation temperature in the evaporator 15.

Next, in step S <b> 3, the control device 30 calculates the superheat degree SH of the refrigerant after passing through the evaporator 15. Specifically, the superheat degree SH is calculated by the following equation (3).
SH = Tco-Tcm (3)

Next, in step S4, the control device 30 obtains the opening degree C _Pls of the cooling expansion valve 14 for adjusting the superheat degree SH to a predetermined target value. Specifically, first, the control device 30 calculates a difference ΔSH between the current superheat degree SH and the target superheat degree SHm by the following equation (4).
ΔSH = SH-SHm (4)

Next, the control device 30 obtains the operation amount ΔC _Pls of the opening degree of the cooling expansion valve 14 using the difference ΔSH in superheat degree. In the present embodiment, as shown in the following equation (5), the manipulated variable ΔC _Pls of the opening degree of the cooling expansion valve is calculated from the difference ΔSH in superheat degree by feedback control such as PID control.
ΔC _Pls = PID (ΔSH) (5)

Then, the opening degree C _Pls of the cooling expansion valve 14 is obtained by the following equation (6).
C _Pls = C _Pls (current value) + ΔC _Pls (6)

In step S5, the control device 30 operates the cooling expansion valve 14 so that the opening degree _CPls calculated by the equation (6) is obtained.

Next, in step S6, the indoor air suction temperature Ta to the indoor unit 3 is detected by the first air temperature sensor Sa1.
And in step S7, the control apparatus 30 _{calculates |} requires opening degree R _Pls of the _rethermal expansion valve 23 for adjusting the suction temperature Ta to a predetermined target value. Specifically, first, the control device 30 calculates a difference ΔTa between the current suction temperature Ta and the target suction temperature Tam by the following equation (7).
ΔTa = Ta−Tam (7)

And the operation amount (DELTA) R _Pls of the opening degree of the rethermal expansion valve 23 is acquired using the difference (DELTA) Ta of suction temperature. In this embodiment, as shown in the following equation (8), the manipulated variable ΔR _Pls of the opening degree of the rethermal expansion valve 23 is calculated from the suction temperature difference ΔTa by feedback control such as PID control.
ΔR _Pls = PID (ΔTa) (8)

Next, the opening degree RPls of the reheat expansion valve 23 is obtained by the following equation (9).
R _Pls = R _Pls (current value) −ΔR _Pls (9)

In step S8, the control device 30 compares the opening degree R _{Pls of the rethermal} expansion valve 23 calculated in step S7 with a predetermined upper limit value R _Max and reheat expansion that actually uses the smaller value. Processing to determine the opening degree R _{Pls of the} valve 23 is performed.
The predetermined upper limit value R _Max is a cooling capacity φ _C (see the above formula (1)) in the evaporator 15 and reheating by the indoor condenser 22 so that the degree of superheat by the cooling expansion valve 14 can be adjusted. It is set based on the ratio with the capacity φ _R (see the above formula (2)). That is, when the ratio is ξ, the upper limit value R _Max is set so that the following expression (10) is satisfied.
ξ · φ _C = φ _R (10)

This ratio ξ is determined as appropriate based on the environment in which the air conditioner 1 is installed, operating conditions, and the like, and is a fixed value set in advance for the air conditioner 1. For example, a range of 0 <ξ ≦ 1 Set within.
In step S9, the control device 30 controls the opening degree of the _rethermal expansion valve 23 by the determined opening degree R _Pls .

By controlling the cooling expansion valve 14 and the reheat expansion valve 23 as described above, the ratio of the refrigerant circulation amount in the indoor condenser 22 to the refrigerant circulation amount in the evaporator 15 does not become excessively large. The degree of superheat of the refrigerant after passing through the evaporator 15 can be controlled by the cooling expansion valve 14.

In step S7, the operation amount ΔR _Pls of the opening degree of the rethermal expansion valve 23 is obtained based on the difference ΔTa between the suction temperature Ta and the target value Tam, but instead, the third refrigerant The difference between the refrigerant temperature at the outlet of the indoor condenser 22 detected by the temperature sensor Sb3 and the set temperature, the refrigerant temperature at the outlet of the indoor condenser 22 detected by the third refrigerant temperature sensor Sb3, and the fifth refrigerant temperature sensor. The difference between the refrigerant temperature flowing through the indoor condenser 22 detected by Sb5, the refrigerant temperature at the inlet of the indoor condenser 22 detected by the fourth refrigerant temperature sensor Sb4, and the indoor condenser detected by the third refrigerant temperature sensor Sb3 It can also be determined by PID control or the like based on the difference from the refrigerant temperature at the outlet 22 or the like.

<Application control 1>
In the basic control described above, the upper limit value R _Max of the opening degree of the rethermal expansion valve 23 is a fixed value. However, if the cooling capacity in the evaporator 15 is reduced in accordance with a decrease in the external load such as heat entering from the outside during the operation of the air conditioner 1, the reheating capacity becomes relatively high, and the cooling expansion valve 14 It may be difficult to adjust the degree of superheat due to. This will be described in detail below.

4A and 4B are explanatory diagrams showing the relationship between the cooling capacity and the reheat capacity associated with the change in the external load. FIG. 4A shows a comparative example, and FIG. 4B shows the application control 1.
FIG. 4A shows the relationship among the external load, the cooling capacity in the air conditioner, and the reheat capacity when the opening degree of the reheat expansion valve 23 is fixed at a predetermined upper limit value. As it goes from (I) to the lower stage (III), the external load decreases.

The cooling capacity phi _C and reheat capability phi _R represented by the above Expression (1) and (2), the differential pressure [Delta] P _C, [Delta] P _R and the enthalpy difference _h C, when the change of the _{h R} is small, the expansion greatly depends on the flow coefficient CV _C and CV _R valves 14 and 23. Therefore, for example, to reduce the cooling capacity phi _C is the flow coefficient _CV C of the

expansion valves

14, 23, squeezing the

respective expansion valves

14 and 23 reduces the CV _R, if caused to decrease the circulation amount of refrigerant It will be good. However, (when the flow coefficient CV _R is constant) when the opening of the reheat expansion valve 23 is fixed, to reduce the cooling capacity phi _C reduces only the flow coefficient CV _C of the cooling expansion valve 14 There is a need.

4 as shown in (I) of (a), when the outside load is large, the circulation amount of the refrigerant flowing in the evaporator 15 is large and the cooling capacity phi _C higher, the indoor condenser 22 for these circulation rate and reheat capability phi _R of the refrigerant flowing becomes relatively small. That is, for the cooling capacity phi _C by the evaporator 15, the ratio of the reheating capacity phi _R by the indoor condenser 22 is reduced, adjustment of the degree of superheat by cooling expansion valve 14 becomes relatively easy.

When the opening degree of the reheat expansion valve 23 is fixed, as shown in (II), even if the external load is reduced, the refrigerant circulation amount of the indoor condenser 22 is hardly changed, and the evaporator is opposed to this. refrigerant circulation amount of 15 is reduced (flow coefficient CV _C decreases) Therefore, the ratio of the reheating capacity phi _R gradually increases with respect to cooling capacity phi _C.

As shown in (III), when the cooling capacity is further reduced due to a decrease in the external load, for example, when the cooling capacity φ _C is halved compared to (I), the reheating capacity φ _R of the cooling capacity φ _C The ratio is about double. In other words, the ratio of the refrigerant circulation amount of the indoor condenser 22 to the refrigerant circulation amount of the evaporator 15 is about twice from the state (I). For this reason, it is very difficult to adjust the degree of superheat by the cooling expansion valve 14.

In the application control 1, in order to eliminate such inconvenience, the upper limit of the opening degree of the reheat expansion valve 23 is adjusted according to the fluctuation of the cooling capacity. Specifically, as shown in FIG. 4 (b), when the outer load toward (I) ~ (III) decreases gradually at a constant ratio to the size of the cooling capacity phi _C again reduce heat capacity phi _R. More specifically, the refrigerant circulation amount flowing through the indoor condenser 22 is decreased at a constant ratio with respect to the refrigerant circulation amount flowing through the evaporator 15. Therefore, the upper limit of the opening degree of the rethermal expansion valve 23 is decreased at a predetermined ratio in accordance with the change in the opening degree of the cooling expansion valve 14. Thereby, the ratio of the refrigerant circulation amount of the indoor condenser 22 to the refrigerant circulation amount of the evaporator 15 is not excessively increased, and the degree of superheat by the cooling expansion valve 14 can be adjusted. This control is executed by the function of the upper limit adjustment unit 33 in the control device 30 as shown in FIG.

Details of the application control 1 will be described below.
FIG. 5 is a flowchart showing the procedure of the application control 1 of the air conditioner.
Steps S11 to S17, S19, and S20 in FIG. 5 are substantially the same as steps S1 to S9 in FIG. In the application control example 1, the upper limit of the opening degree of the rethermal expansion valve 23 is changed according to the opening degree of the cooling expansion valve 14 in step S18 in FIG.

Specifically, as shown in the following equation (11), the opening _CPLs of the cooling expansion valve 14 calculated in step S14 is _added to the predetermined coefficient ζ and the maximum flow rates of the cooling expansion valve 14 and the rethermal expansion valve 23. The upper limit value R _Max ′ of the reheat expansion valve 23 is calculated by multiplying the ratios of the coefficients CVc and CVr.
R _Max '= ζ · CVc / CVr · C _Pls (11)

The predetermined coefficient ζ is obtained from the above equations (1), (2), and (10), the ratio ξ between the cooling capacity φ _C and the reheating capacity φ _R , and the differential pressure ΔP _C between the high pressure and the low pressure of the refrigerant. , the ratio of [Delta] P _R, enthalpy difference h _C between the cooling side and the reheating _side, the ratio of h _R, the high pressure side density ratio G _C, are set in consideration of the ratio and the like of the G _R, superheat by cooling expansion valve 14 This is a value for converting the opening degree of the cooling expansion valve 14 into the opening degree of the rethermal expansion valve 23 within a range that allows adjustment of the above.

Next, in step S19, the control device 30 compares the opening degree R _Pls of the _rethermal expansion valve 23 calculated in step S17 with the upper limit value R _Max ′ of the opening degree calculated in step S18, and the smaller. _Is determined as the opening degree R _Pls of the reheat expansion valve 23 actually used. By controlling the opening degree of the reheat expansion valve 23 with the opening degree R _Pls determined in this way, the ratio of the refrigerant circulation amount of the indoor condenser 22 to the refrigerant circulation amount of the evaporator 15 becomes excessively large. Therefore, the degree of superheat by the cooling expansion valve 14 can be adjusted suitably.

<Modification of Application Control 1>
The cooling capacity in the evaporator 15 and the reheat capacity in the indoor condenser are expressed by the above formulas (1) and (2), but can be replaced by other methods. For example, as shown in the following equation (12), the cooling capacity of the evaporator 15 is determined by a difference T1 (evaporator) between the temperature t1 detected by the first air temperature sensor Sa1 and the temperature t3 detected by the third air temperature sensor Sa3. The temperature T2 of the indoor condenser 22 is replaced with a difference T2 between the temperature t2 detected by the second air temperature sensor Sa2 and the temperature t3 detected by the third air temperature sensor Sa3. It can be replaced by the temperature raised by the condenser 22). Then, by adjusting the upper limit of the opening degree of the rethermal expansion valve 23 so that the ratio between the temperature differences T1 and T2 is equal to or less than the predetermined value α, the reheat expansion valve 23 can be opened according to the change in cooling capacity. The upper limit of degree can be adjusted.
T2 / T1 ≦ α (12)
(However, T1 = t1-t3, T2 = t2-t3)

The ratio α of the temperature differences T1 and T2 can be set, for example, within a range of 0 <α ≦ 1, and as an example, α = 0.3. In this modification, the upper limit of the reheat expansion valve 23 can be easily adjusted by using the detection signal of the air temperature sensor.

<Application control 2>
In the basic control and the application control 1 described above, the upper limit of the opening degree of the reheat expansion valve 23 is set, and the circulation amount of the refrigerant flowing through the indoor condenser 22 is considered. In addition to these, the application control 2 controls the opening degree of the reheat expansion valve 23 so that the degree of supercooling at the outlet of the indoor condenser 22 is appropriately secured.

FIG.6 and FIG.7 is a flowchart which shows the procedure of the application control 2 of an air conditioning apparatus.
Steps S21 to S26 in FIG. 6 are substantially the same as steps S1 to S6 in FIG. 3, and the control device 30 obtains the superheat degree SH from the evaporator outlet temperature Tco and the evaporator intermediate temperature Tcm, and this superheat degree SH. The cooling expansion valve 14 is operated by _obtaining the opening C _Pls of the cooling expansion valve 14 with the target value as the target value. In step S26, the first air temperature sensor Sa1 detects the indoor air suction temperature Ta to the indoor unit 3.

In step S27, the control device 30 acquires the operation amount ΔR _Pls of the opening degree of the _rethermal expansion valve 23 so that the suction temperature Ta is set to a predetermined target value. Specifically, first, the difference ΔTa between the current suction temperature Ta and the target suction temperature Tam is calculated by the above equation (7).

Then, as shown in the above equation (8), the control device 30 calculates the manipulated variable ΔR _Pls of the opening degree of the rethermal expansion valve 23 from the suction temperature difference ΔTa by feedback control such as PID control.

Next, in step S28 of FIG. 7, the refrigerant temperature Trev is detected by the third refrigerant temperature sensor Sb3, and the refrigerant pressure Prev is detected by the first pressure sensor Sc1. In step S29, the degree of supercooling SC at the outlet of the indoor condenser 22 is calculated using these values Trev and Prev. Specifically, first, the saturated liquid temperature Tsl is obtained from the refrigerant pressure Prev at the outlet of the indoor condenser 22 (before the reheat expansion valve 23), and this saturated liquid temperature Tsl and the outlet of the indoor condenser 22 (reheated) The supercooling degree SC is calculated from the refrigerant temperature Trev before the expansion valve 23 by the following equation (13).
SC = Tsl−Trev (13)

Next, in step S30, the control device 30 determines whether or not the supercooling degree SC is greater than a predetermined threshold, here “3 degrees”.
If the degree of supercooling SC is greater than 3 degrees, it is considered that the degree of supercooling is sufficiently secured. Therefore, in step S31, the adjustment amount dSC _Pls of the rethermal expansion valve 23 based on the degree of supercooling SC is set to zero. Then, the process proceeds to step S34.

On the other hand, when the degree of supercooling SC is 3 degrees or less, it is considered that the degree of supercooling is not sufficiently ensured. Therefore, in step S32, the adjustment amount dSC _Pls of the reheat expansion valve 23 is expressed by the following equation (14). Ask.
dSC _Pls = γ · {3-max (SC, 0)} (14)
Here, when the degree of supercooling SC exceeds 0 degree, the adjustment amount dSC _Pls is obtained by subtracting the degree of supercooling SC from the threshold “3 degrees” and multiplying by a predetermined correction coefficient γ. When the degree of supercooling SC is 0 degrees or less, the adjustment amount dSC _Pls is obtained by multiplying the threshold “3 degrees” by a predetermined correction coefficient γ.

The correction coefficient γ is set to ensure an appropriate supercooling degree SC according to the state of the apparatus, the installation environment, and the like. For example, the correction coefficient γ sets the necessary supercooling degree SC to the rethermal expansion valve 23. The pulse conversion coefficient is used to convert the number of pulses of the motor. This pulse conversion coefficient γ can be obtained as follows.
As shown in FIG. 8, when the enthalpy at the measurement point of the supercooling degree SC is h _SC , the saturated liquid enthalpy at the measurement point of the supercooling degree SC is h _sl , and the enthalpy at the inlet of the indoor condenser 22 is h _ri. The enthalpy h corresponding to the degree of supercooling of 1 degree is expressed by the following equation (15).
h = (h _sl -h _SC ) / SC (15)

The refrigerant circulation rate ratio at this time is h / (h _ri -h _SC ), and the pulse conversion coefficient γ necessary for changing the degree of supercooling SC once is given by the following equation (16).
γ = Cv ′ × h / (h _ri −h _SC ) / Cv × MaxPls (16)
Here, Cv ′ is a flow coefficient with respect to the current opening degree of the rethermal expansion valve 23, Cv is a flow coefficient when the reheat expansion valve 23 is fully opened (so-called CV value), and MaxPls is a fully open state of the reheat expansion valve 23. The number of pulses at the time.

Next, in step S33, the control device 30 compares the operation amount ΔR _Pls of the opening degree of the reheat expansion valve 23 calculated in step S27 with 0, and determines a larger value as the operation amount ΔR _Pls that is actually used. To do.

The manipulated _variable ΔR _Pls of the opening degree of the _rethermal expansion valve 23 calculated in step S27 takes a positive value (ΔR _Pls > 0) when the suction temperature Ta is higher than the target suction temperature Tam (Ta> Tam). Conversely, when the suction temperature Ta is lower than the target suction temperature Tam (Ta <Tam), it takes a negative value (ΔR _Pls <0). Therefore, when ΔR _Pls is a positive value, the reheat expansion valve 23 is closed in order to reduce the reheat capability. When ΔR _Pls is a negative value, more reheat capability is required. Therefore, it becomes operation of the direction which opens the reheat expansion valve 23. FIG. However, since priority is given to securing the degree of supercooling SC in the application control 2, in the process of step S33, it is excluded to operate the reheat expansion valve 23 in the opening direction, and the reheat expansion valve 23 is excluded. Only the operation in the closing direction is adopted.

Next, in step S34, the adjustment amount dSC _Pls obtained in step S31 or S32 is added to the operation amount ΔR _Pls of the opening degree of the rethermal expansion valve 23 obtained in step S33, and the operation amount ΔR _Pls actually used is obtained. Then, as the opening degree R _Pls of the reheat expansion valve 23, a value obtained by subtracting the operation amount ΔR _Pls from the current opening degree R _Pls is compared with a predetermined upper limit value R _Max. The opening degree R _Pls of the thermal expansion valve 23 is determined. In step S35, the control device 30 operates the reheat expansion valve 23.

In this application control 2, when the degree of supercooling SC is smaller than a predetermined threshold (for example, “3 degrees”), the rethermal expansion valve 23 is operated in a direction to sufficiently secure the degree of supercooling SC. Therefore, inconvenience due to the insufficient degree of supercooling SC can be solved. The inconvenience is that the gas-liquid two-phase refrigerant flows into the reheat expansion valve 23 to rapidly reduce the refrigerant circulation amount to the indoor condenser 22 and disturb the superheat degree control, and the outdoor unit 2 is thermo-off and dehumidified. The capacity decreases, or conversely, when the gas-liquid two-phase state is canceled, the refrigerant circulation amount is rapidly recovered, and the dryness of the refrigerant at the outlet of the evaporator 15 is drastically reduced, making it difficult to protect the compressor. It is conceivable.

The degree of supercooling SC at the outlet of the indoor condenser 22 is obtained by detecting the temperature intermediate between the outlet of the indoor condenser 22 by the refrigerant temperature sensors Sb3 and Sb5 and subtracting the intermediate temperature from the temperature on the outlet side. be able to. Or it can also obtain | require by correct | amending the discharge pressure of the compressor 12 by piping pressure loss.

[Second Embodiment]
FIG. 9 is a schematic configuration diagram showing an air-conditioning apparatus according to the second embodiment of the present invention.
As shown in FIG. 9, the air conditioner (refrigeration apparatus) 1 includes an outdoor unit (heat source side unit) 2 and an indoor unit (use side unit) 3. In the cooling circuit 10, a receiver 18 and a cooling electromagnetic valve 25 are provided between the outdoor condenser (heat source side heat exchanger) 13 of the outdoor unit 2 and the cooling expansion valve 14 of the indoor unit 3. The receiver 18 is provided in the outdoor unit 2, and the cooling electromagnetic valve 25 is provided in the indoor unit 3.

In order to adjust the pressure inside the receiver 18 in the path 11a which is a heat source side gas pipe connected between the discharge side of the compressor 12 and the gas side end of the outdoor condenser (heat source side heat exchanger) 13. One end of the pressure adjusting passage 19 is connected, and the other end of the pressure adjusting passage 19 is connected to a position closer to the upper side of the container of the receiver 18. The pressure adjusting passage 19 is provided with a pressure adjusting electromagnetic valve 27. By opening and closing the pressure adjusting electromagnetic valve 27 at a predetermined timing (repeats opening and closing operations), the amount of discharge gas (high pressure gas) of the compressor 12 introduced into the receiver 18 is changed, The pressure in the receiver 18 can be adjusted. The lower end of the receiver 18 is connected to the cooling electromagnetic valve 25 of the indoor unit 3 through a refrigerant pipe.

In the reheat path 21, the reheat refrigerant pipe 45 on the refrigerant inflow side of the indoor condenser (reheat heat exchanger) 22 is provided with a reheat electromagnetic valve (first reheat valve) 26. Yes. The reheating refrigerant pipe 45 is connected to a reheating bypass pipe 46 that bypasses the reheating first on-off valve 26. The reheating bypass pipe 46 is connected to a reheating second opening / closing valve 28 having a smaller diameter than the reheating first opening / closing valve 26.

Further, the indoor unit 3 is provided with a suction air humidity sensor Sd1 for measuring the humidity of the suction air of the evaporator 15.

The controller 30 controls the operation of the reheat dehumidification mode in which the air cooled and dehumidified by the evaporator 15 as described in the first embodiment is heated by the indoor condenser 22, and in addition to this, the evaporator 15 Operation control in the cooling mode in which the cooled and dehumidified air only passes through the indoor condenser 22 can be performed. For example, the control device 30 operates in the reheat dehumidification mode in which the air cooled by the use-side heat exchanger 15 that is an evaporator is heated by the indoor condenser (reheat heat exchanger) 22 during the operation in the cooling mode. Is also configured to control.

Specifically, the control device 30 determines that the intake air temperature of the evaporator 15 is within a target temperature range (eg, within a range of 13 ° C. to 17 ° C.) and the relative humidity of the intake air is equal to or higher than the target humidity (eg, 45%). When the reheat dehumidification mode is operated at a certain time, the suction air temperature of the evaporator is higher than the target temperature, or the suction air temperature is within the target temperature range (for example, within a range of 13 ° C to 17 ° C) When the relative humidity of the intake air is lower than the target humidity, the cooling mode operation is performed.

<Driving action>
In the air conditioning apparatus (refrigeration apparatus) 1 of the present embodiment, the control device 30 performs switching control between the cooling mode and the reheat dehumidification mode during operation.
For example, when the air conditioner 1 is activated, it is necessary to cool the inside of the warehouse as meat is brought into the inside of the suspension cabinet or the like, so the area indicated as the cooling / reheating mode in FIG. Is operated in the cooling mode (cooling pull-down for rapidly cooling the interior). When the inside temperature is between 13 ° C and 17 ° C, the operation is performed while switching between the cooling mode and the reheat dehumidification mode.

Specifically, when the intake air temperature (inside air temperature) of the evaporator 15 is within the range of 13 ° C. to 17 ° C., which is the target temperature, and the relative humidity of the intake air is equal to or higher than the target humidity (45% RH). In the reheat dehumidification mode, the intake air temperature of the evaporator 15 is higher than the target temperature (17 ° C.), or the intake air temperature is within the target temperature range of 13 ° C. to 17 ° C. and the intake air When the relative humidity is less than the target humidity (45% RH), the operation control is performed by the control device 30 so that the operation in the cooling mode is performed.

As shown in FIG. 10, the air conditioner of the present embodiment is configured to be capable of operating in a refrigeration mode or a refrigeration mode, and has a set temperature of 0 ° C. (the internal temperature is approximately 10 ° C. to −5 ° C.). ) In the refrigeration mode, the operation in the refrigeration mode is performed at a set temperature of −20 ° C. (a state where the internal temperature is lower than −5 ° C.).

(Operation mode switching)
Next, the operation mode switching operation described above will be described more specifically based on the flowchart of FIG.
In step S41, it is determined whether or not the air conditioner 1 is in operation. If the determination result is “YES” and the vehicle is operating, the process proceeds to step S42 to determine whether the intake air temperature of the evaporator 15 is 17 ° C. or higher, and the determination result of step S41 is “NO”. If there is no operation, the process proceeds to step S43 to stop the process and then returns to step S41.

When the determination result in step S42 is “YES” and the intake air temperature is 17 ° C. or higher, the process proceeds to step S44, the apparatus is thermo-ON, and the operation in the cooling mode is performed. During the operation in the cooling mode, the determination in step S41 is always performed.

When the determination result of step S42 is “NO” and the intake air temperature is less than 17 ° C., the process proceeds to step S45, and it is determined whether or not the intake air temperature is 13 ° C. or less. If the determination result is “NO”, the intake air temperature is lower than 17 ° C. and higher than 13 ° C. In this case, it is determined in step S46 whether the relative humidity RH is 45% or more. When the determination result is “NO”, the relative humidity RH is less than 45%, and the humidity is not high. Therefore, the process proceeds to step S44 to perform the cooling mode operation, and the process returns to the determination of step S41.

If the result of determining in step S45 whether or not the intake air temperature is 13 ° C. or less is “YES”, the inside of the refrigerator is sufficiently cooled. In this case, the process proceeds to step S47 and the thermo is turned off. The inside is a mode in which only blowing is performed. In the air blowing operation mode, the determination in step S41 is always performed as in the cooling mode.

If the result of determining in step S45 whether or not the relative humidity RH is 45% or more is “YES”, the humidity in the cabinet is lower than 17 ° C. and higher than 13 ° C. (within the predetermined range of the present invention). However, since the humidity is high, the process proceeds to step S48 to switch to the reheat dehumidification mode, where the dehumidification is performed while maintaining the temperature. Even in the reheat dehumidifying mode, the determination in step S41 is always performed as in the cooling mode.

<States of refrigerant circuit components in each operation mode>
Next, the driving operation in each mode will be described. In each mode, various valves, fans, and compressors are controlled to the states shown in FIG. In FIG. 12, “unit cooler” represents the indoor unit (use side unit) 3, and the refrigerator represents the outdoor unit (heat source side unit) 2. “SV1” is a cooling solenoid valve 25, “SV2” is a reheating solenoid valve 26, “EV1” is a cooling expansion valve 14, “EV2” is a rethermal expansion valve 23, and “MF1” is an indoor fan. A (use side fan) 17 is shown. “MF2” indicates the outdoor fan (heat source side fan) 16, “MC” indicates the compressor 12, and “SV4” indicates the pressure adjusting electromagnetic valve 27.

(Cooling mode)
In the operation in the cooling mode (thermo-on), the cooling solenoid valve 25 is “open”, the reheating solenoid valve 26 is “closed”, and the cooling expansion valve 14 is superheat controlled (the superheat degree of the outlet refrigerant of the evaporator 15 is the target). The reheat expansion valve 23 is “closed (fully closed)”, the indoor fan 17 has a large air volume (H air volume), and the outdoor fan 16 and the pressure adjusting solenoid valve 27 are targets. Control based on the high pressure (high pressure control), the frequency of the compressor 12 is controlled by the inverter control so as to reach the target operating capacity.

In this state, the refrigerant discharged from the compressor 12 flows into the outdoor condenser 13 and dissipates heat. At this time, when the pressure of the refrigerant flowing out of the outdoor condenser 13 cannot be controlled to the target pressure, the pressure adjusting electromagnetic valve 27 is controlled to open and close. Specifically, when the low pressure of the refrigerant circuit is lower than the treatment value, the pressure adjusting electromagnetic valve 27 is opened to introduce the high pressure refrigerant into the receiver 18, and the high pressure flowing through the liquid side communication pipe connected from the receiver 18 to the indoor unit 3. Adjust the pressure of the liquid refrigerant.

The high-pressure liquid refrigerant passes through the cooling electromagnetic valve 25 in the indoor unit 3, is depressurized by the cooling expansion valve 14, and is evaporated by absorbing heat from the internal air in the evaporator 15. At this time, the internal air is cooled in the evaporator 15. The evaporated refrigerant returns to the outdoor unit 2 and is sucked into the compressor 12.

The operation in the cooling mode (thermo-on) is performed by circulating the refrigerant through the refrigerant circuit as described above.

In the operation in the cooling mode (thermo-off), the indoor fan 17 rotates with a large air volume, while the various valves and the compressor 12 are stopped, and only air is blown in the warehouse.

(Reheat dehumidification mode)
In the reheat dehumidification mode, part of the control of various valves is different from the cooling mode. Specifically, the reheat electromagnetic valve 26 is controlled to be “open”, the reheat expansion valve 23 is controlled based on the intake air temperature, and the indoor fan 17 has a low air volume (L air volume).

In this state, the refrigerant discharged from the compressor 12 circulates in the refrigerant circuit using the heat source side heat exchanger 13 and the reheat heat exchanger 22 as a radiator (condenser) and the use side heat exchanger 15 as an evaporator. To do. In the indoor unit 3, the internal (indoor) air is cooled and dehumidified by the evaporator 15 and then heated by the indoor condenser 22, so that the humidity is reduced while suppressing a decrease in the internal temperature.

In addition, when starting the operation in the reheat dehumidification mode, the control device 30 opens the reheat expansion valve 23 in a state in which the reheat electromagnetic valve (first reheat valve) 26 is closed, and then performs a predetermined operation. The reheat second on-off valve 28 is opened after a time (for example, 5 seconds), and the reheat first on-off valve 26 is opened after a predetermined time (for example, 5 minutes) to perform the liquid refrigerant removal operation. ing.

Further, when the control device 30 ends the operation in the reheat dehumidification mode, the reheat is performed after a predetermined time (for example, 4 minutes) after the reheat first on-off valve 26 and the reheat second on-off valve 28 are closed. The expansion valve 23 is closed. As described above, the opening /

closing valves

26 and 28 having different (large and small) diameters are provided in parallel on the refrigerant inflow side of the indoor condenser (reheat heat exchanger) 22, and the diameter is reduced when the reheat dehumidifying mode is operated. After opening the small opening / closing valve 28 first, the opening / closing valve 26 having a large diameter is opened after a predetermined time. This is because the on-off valve 26 is closed during the cooling operation, so that when the refrigerant flowing into the reheating refrigerant pipe 45 accumulates and liquefies, the on-off valve 26 is immediately opened when the reheat dehumidifying mode is started. And the liquid refrigerant flows into the reheat expansion valve 23 at once, and the reheat expansion valve 23 whose opening degree is controlled so as to give priority to the degree of supercooling may cause the pipe to vibrate without being able to process the refrigerant. It is.

The operation in the reheat dehumidification mode will be specifically described with reference to the time chart of FIG.
When operation in the reheat dehumidification mode is started at time T1, an operation of opening the reheat expansion valve 23 (shown as EV2 in FIG. 13) is performed at that time. At this time, the reheating first on-off valve 26 (shown as SV2 in FIG. 13) and the reheating second on-off valve 28 (shown as SV5 in FIG. 13) remain closed.

When t1 seconds (for example, 5 seconds) elapse from time T1 and time T2 is reached, an operation of opening the reheating second on-off valve 28 is performed while the reheating first on-off valve 26 is closed. Since the reheating second on-off valve 28 has a smaller diameter than the reheating first on-off valve 26, the liquid refrigerant accumulated in the reheating refrigerant pipe 45 during the cooling operation is condensed in small amounts in the room. It flows through the vessel 22 and passes through the rethermal expansion valve 23. During operation in the reheat dehumidification mode, the opening degree of the reheat expansion valve 23 is adjusted so that priority is given to the degree of supercooling of the refrigerant on the outlet side of the indoor condenser 22, and the opening degree is set to be small. There is. However, in this embodiment, the diameter of the reheat second on-off valve 28 is small, and the flow rate of the refrigerant flowing to the reheat expansion valve 23 is limited. Therefore, the liquid refrigerant does not pass through the reheat expansion valve 23 at a stretch, so that the vibration of the pipe is suppressed.

When the operation in this state is performed for t2 seconds (for example, 300 seconds (5 minutes)) and time T3 is reached, it is determined that the liquid refrigerant accumulated in the reheating refrigerant pipe 45 has passed through the reheat expansion valve 23, and The second heat on-off valve 28 is switched to ON (open). Thereafter, for t3 seconds until time T4, while the opening degree of the reheat expansion valve 23 is controlled, the indoor air cooled and dehumidified by the evaporator 15 is heated by the indoor condenser 22, and the temperature drop in the internal combustion chamber is suppressed. The operation to lower the humidity is performed.

When the operation in the reheat dehumidification mode is completed at time T4, the reheat first on-off valve 26 and the reheat second on-off valve 28 are closed, and the subsequent t4 seconds (for example, 240 seconds (4 minutes)) are restarted. The thermal expansion valve 23 is opened, and the liquid refrigerant in the indoor condenser 22 is evaporated by the evaporator 15 and recovered to the compressor 12.

<Effects of Second Embodiment>
According to this embodiment, when the intake air temperature of the evaporator 15 is within the target temperature range (13 ° C. to 17 ° C.) and the relative humidity of the intake air is equal to or higher than the target humidity (45% RH), the internal space Since the humidity is relatively high with respect to the temperature, the reheat dehumidification mode operation is performed so as to reduce the humidity without lowering the temperature. On the other hand, the intake air temperature of the evaporator 15 is higher than the target temperature, or the intake air temperature of the evaporator 15 is within the target temperature range (13 ° C. to 17 ° C.) and the relative humidity of the intake air is less than the target humidity. If there is, the operation in the cooling mode is performed so as to lower the temperature in preference to the humidity. Thus, since the reheat dehumidification mode and the cooling mode are performed according to the state of the intake air, the humidity and temperature of the internal space can be controlled to appropriate values.

According to the present embodiment, since the liquid refrigerant can be prevented from flowing into the reheat expansion valve 23 at the same time when the operation in the reheat dehumidification mode is started, the vibration noise of the pipe can be suppressed. In FIG. 13 of the present embodiment, the time exemplified as t1 to t4 may be appropriately changed according to the reheat refrigerant pipe 45 and the pipe length of the reheat path 21. The reheat second opening / closing valve 28 has a smaller diameter than the reheating first opening / closing valve 26 according to the amount of liquid refrigerant expected to be accumulated in the reheating refrigerant pipe 45 during the cooling operation. Can be set as appropriate.

The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made within the scope described in the claims.
For example, the air conditioning apparatus of the present invention is not limited to a meat factory and can be used in any environment.

In the above embodiment, the reheat dehumidification is performed when the intake air temperature of the evaporator 15 is within the target temperature (13 ° C. to 17 ° C.) and the relative humidity of the intake air is equal to or higher than the target humidity (45% RH). Mode, the intake air temperature of the evaporator (17) is higher than the target temperature, or the intake air temperature is within the target temperature (13 ° C to 17 ° C) and the relative humidity of the intake air is the target humidity However, the present invention is not limited to this configuration, and even when control is performed with this configuration, the above-described target temperature and target humidity are configured. Can be appropriately changed.

1: Air conditioner 11: Cooling circuit 11a: Path 11b: Path 12: Compressor 13: Outdoor condenser 14: Cooling expansion valve 15: Evaporator 21: Reheat path 22: Indoor condenser 23: Rethermal expansion valve 30 : Control device 31: Cooling control unit 32: Reheat control unit 33: Upper limit adjustment unit

Claims

A compressor (12);
An outdoor condenser (13) for condensing the refrigerant compressed by the compressor (12);
A cooling expansion valve (14) for depressurizing the refrigerant condensed in the outdoor condenser (13);
An evaporator (15) for evaporating the refrigerant decompressed by the cooling expansion valve (14) by heat exchange with room air to cool and dehumidify the room air;
A cooling circuit (11) connecting the compressor (12), the outdoor condenser (13), the cooling expansion valve (14), and the evaporator (15) in this order;
The cooling circuit (11) branches from a path (11a) connecting the compressor (12) and the outdoor condenser (13), and connects the cooling expansion valve (14) and the evaporator (15). A reheat path (21) connected to the path (11b)
In the reheat path (21), the refrigerant compressed by the compressor (12) is condensed by heat exchange with the indoor air cooled and dehumidified by the evaporator (15) to heat the indoor air. A condenser (22);
A reheat expansion valve (23) for depressurizing the refrigerant condensed in the indoor condenser (22) in the reheat path (21);
A control device (30) for controlling the opening degree of the cooling expansion valve (14) and the reheat expansion valve,
The control device (30)
A cooling control unit (31) for adjusting the refrigerant circulation amount of the evaporator (15) and adjusting the degree of superheat of the refrigerant after passing through the evaporator (15) by controlling the opening degree of the cooling expansion valve (14); ,
A reheat control unit (32) for adjusting a room temperature by adjusting a refrigerant circulation amount of the indoor condenser (22) by opening degree control of the reheat expansion valve (23),
The reheat expansion valve (23) is a ratio of the cooling capacity in the evaporator (15) and the reheat capacity in the indoor condenser (22) that allow adjustment of the degree of superheat by the cooling expansion valve (14). The air conditioner in which the upper limit of the opening degree controlled by the said reheat control part (32) is set based on this.
The control device (30) further includes an upper limit adjustment unit (33) that adjusts an upper limit of the opening degree of the reheat expansion valve (23) according to a change in cooling capacity of the evaporator (15) during operation. The air conditioner according to claim 1, comprising:
The upper limit of the opening degree of the reheat expansion valve (23) is adjusted based on the ratio between the refrigerant circulation amount flowing through the cooling expansion valve (14) and the refrigerant circulation amount flowing through the reheat expansion valve (23). The air conditioning apparatus according to claim 2.
The upper limit of the opening degree of the reheat expansion valve (23) is an air temperature difference before and after passing through the evaporator (15) and an air temperature difference before and after passing through the indoor condenser (22). The air conditioning apparatus according to claim 2, wherein the air conditioning apparatus is adjusted based on a ratio.
The reheat control unit (32) corrects the control amount of the opening degree of the reheat expansion valve (23) according to the degree of supercooling of the refrigerant at the outlet of the indoor condenser (22), and the degree of supercooling. The air conditioner according to any one of claims 1 to 4, wherein the air conditioner is adjusted.
The control device (30) controls the operation in a reheat dehumidification mode in which the air cooled and dehumidified by the evaporator (15) is heated by the indoor condenser (22), and cooled and dehumidified by the evaporator (15). In the cooling mode in which only the passed air passes through the indoor condenser (22), and the intake air temperature of the evaporator (15) is within the target temperature range and the relative intake air When the humidity is equal to or higher than the target humidity, the reheat dehumidification mode is operated, and the intake air temperature of the evaporator (15) is higher than the target temperature, or the intake air temperature is within the target temperature range and The air conditioner according to any one of claims 1 to 5, wherein the air conditioner is configured to perform a cooling mode operation when a relative humidity of the intake air is lower than a target humidity.
The reheat first on-off valve (26) is connected to the reheat refrigerant pipe (45) on the refrigerant inflow side of the indoor condenser (22) during operation in the reheat dehumidification mode, and the indoor condenser (22 ) Is connected to the refrigerant outflow side of the reheat expansion valve (23),
The reheat refrigerant pipe (45) is connected to a reheat bypass pipe (46) that bypasses the first reheat valve (26), and the reheat bypass pipe (46) is connected to the reheat bypass pipe (46). The air conditioning apparatus according to claim 6, wherein a second reheating on-off valve (28) having a smaller diameter than the first reheating on-off valve (26) is connected.
The controller (30) opens the reheat expansion valve (23) with the reheat first on-off valve (26) closed when starting the operation in the reheat dehumidification mode. The liquid refrigerant removing operation for opening the second reheating on-off valve (28) after a predetermined time and opening the first reheating on-off valve (26) after the predetermined time is performed. The air conditioning apparatus according to 7.
The control device (30) closes the reheat first on-off valve (26) and the reheat second on-off valve (28) for a predetermined time when the operation of the reheat dehumidification mode is finished. The air conditioner according to claim 8, wherein the air conditioner is configured to close the reheating expansion valve (23) later.