EP2733441A2

EP2733441A2 - Multi-type air conditioner

Info

Publication number: EP2733441A2
Application number: EP13192866.5A
Authority: EP
Inventors: Masahiko Nakamoto; Toru Yamaguchi; Atsushi Enya
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2012-11-16
Filing date: 2013-11-14
Publication date: 2014-05-21
Also published as: JP6129520B2; JP2014102011A; EP2733441A3

Abstract

The present invention has an object to perform an operation with a high degree of freedom in each of an indoor unit (3A,3B,3C) and a water temperature regulation apparatus (40) and perform an efficient operation in accordance with operation states of the indoor unit and the water temperature regulation apparatus. In a mode in which indoor air conditioning by the indoor unit is prioritized, in the case where a target pressure of a refrigerant circuit of an outdoor unit (2) is set in accordance with a set temperature of each indoor unit, a water temperature regulation controller controls the degree of opening of an expansion valve (52) such that the capability of a water heat exchanger does not become equal to or more than 100%. Moreover, in the case where sufficient control cannot be performed by only adjusting the degree of opening of the expansion valve, the amount of water passing through a bypass (72) is adjusted by a water control valve (73), whereby the capability of the water heat exchanger of a water temperature regulation unit can be suppressed to be less than 100%.

Description

{Technical Field}

The present invention relates to a multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit.

{Background Art}

In buildings and the like, multi-type air conditioners in which a plurality of indoor units are connected to one outdoor unit are used.
In addition to such a multi-type air conditioner, a hot water heater and water utilizing equipment such as a heated swimming pool may be provided. In this case, there has been an attempt to perform heat exchange between a refrigerant of the multi-type air conditioner, and heated water and chilled water (hereinafter, simply referred to as water) of the water utilizing equipment, to thereby make mutual efficient use of thermal energy (see, for example, PTL 1 and PTL 2).
In such a configuration, the water utilizing equipment includes a water temperature regulation apparatus including a heat exchanger that performs heat exchange with the refrigerant circulating in the multi-type air conditioner. The water temperature regulation apparatus regulates the temperature of the water used by the water utilizing equipment.

{Citation List}

{Patent Literature}

{PTL 1}
Japanese Unexamined Patent Application, Publication No. Hei 8-261599
{PTL 2}
Japanese Unexamined Patent Application, Publication No. 2008-281319

{Summary of Invention}

{Technical Problem}

Unfortunately, the conventional technique described above has the following problem.
In some multi-type air conditioners, turning on/off of an operation, settings of room temperature, switching between an air cooling operation and an air heating operation, and the like can be performed independently for each of a plurality of indoor units provided in a building. In this case, even if an operation state is different for each of the plurality of indoor units, one outdoor unit needs to deal with the plurality of indoor units. Hence, the outdoor unit performs heat exchange in the state where the target pressure and target temperature of a refrigerant sent out by the outdoor unit are set in accordance with the operation states of the plurality of indoor units, but control therefor is unfavorably complicated.
In view of the above, a method that may be adopted to facilitate the control involves making the target pressure of the refrigerant constant and controlling turning on/off of each indoor unit, to thereby adjust the capability of each indoor unit.
In a configuration in which water utilizing equipment is combined with a multi-type air conditioner, the temperature of water required by the water utilizing equipment is variously different, in addition to the above-mentioned difference in operation state among the plurality of indoor units. Consequently, a target temperature range may be completely different between: indoor air to be temperature-regulated by each indoor unit of the multi-type air conditioner; and water in the water utilizing equipment.
Specifically, when the indoor unit performs an air heating operation, the target temperature of water to be regulated by the water temperature regulation apparatus may be lower than the target temperature of air to be regulated by the indoor unit. On the other hand, when the indoor unit performs an air cooling operation, the target temperature of water to be regulated by the water temperature regulation apparatus may be higher than the target temperature of air to be regulated by the indoor unit.
In this case, for example, in the case where an appropriate target pressure of the refrigerant is set in accordance with the target temperature in the indoor unit, if heat exchange is performed between the refrigerant under this target pressure and the water in the water temperature regulation apparatus, the capability of the water temperature regulation apparatus is excessive. As a result, a waste of energy is generated, and there is room for improvement in efficient use of energy.
Conversely, in the case where an appropriate target pressure of the refrigerant is set in accordance with the target temperature in the water temperature regulation apparatus, the capability of the indoor unit is insufficient. Hence, the set temperature may be limited, and the temperature regulation may take time. As a result, both the indoor unit and the water temperature regulation apparatus cannot perform an operation with a high degree of freedom.
The present invention, which has been made in view of the above-mentioned circumstances, has an object to provide a multi-type air conditioner that can perform an operation with a high degree of freedom and can perform an efficient operation in accordance with operation states of an indoor unit and a water temperature regulation apparatus.

{Solution to Problem}

A multi-type air conditioner according to the present invention includes: an outdoor unit including an outdoor heat exchanger that performs heat exchange between an outdoor heat source and a refrigerant; at least one indoor unit connected to the outdoor unit, the indoor unit including an indoor air heat exchanger that performs heat exchange between the refrigerant supplied from the outdoor unit and indoor air, to thereby condition the indoor air; at least one water temperature regulation apparatus that is connected to the outdoor unit in parallel with the indoor unit, the water temperature regulation apparatus including a water heat exchanger that performs heat exchange between the refrigerant supplied from the outdoor unit and water, to thereby regulate a temperature of the water; a refrigerant circuit that circulates the refrigerant between: the outdoor unit; and the indoor unit and the water temperature regulation apparatus; and an outdoor controller that sets a target pressure of the refrigerant in the refrigerant circuit and operates the outdoor unit such that an actual pressure approaches the set target pressure. The outdoor controller can make switching between: a first mode for an operation in which, when only the water temperature regulation apparatus is operated, the target pressure of the refrigerant is set in accordance with a target water temperature set by the water temperature regulation apparatus; and a second mode for an operation in which, when the indoor unit and the water temperature regulation apparatus are mixedly operated, the target pressure of the refrigerant is set in accordance with the indoor unit.
Moreover, in the second mode, a second-1 mode and a second-2 mode can be selected as appropriate depending on an intended purpose and the like of a user. In the second-1 mode, the indoor air conditioning by the indoor unit is prioritized. In the second-2 mode, the water temperature regulation by the water temperature regulation apparatus is prioritized.
For example, in the case where the indoor unit does not perform the air heating operation or the air cooling operation and where only the water temperature regulation apparatus is operated, the first mode is selected, and the operation is performed in the state where the target pressure of the refrigerant is set in accordance with the set temperature of the water temperature regulation apparatus. As a result, in the water temperature regulation apparatus, the capability thereof is effectively exerted, the pressure of the refrigerant is not excessively increased, and a waste of energy is suppressed, leading to an efficient operation.
Here, in order to set the target pressure of the refrigerant in accordance with the set temperature of the water temperature regulation apparatus, the target pressure of the refrigerant may be varied in a direction in which the water temperature of the water temperature regulation apparatus approaches the set temperature thereof.
Further, in the case of selecting the second mode, it is preferable to combine the following configurations.
That is, the water temperature regulation apparatus includes: an expansion valve that adjusts a degree of superheating or a degree of supercooling of the refrigerant supplied to the water heat exchanger; and a water temperature regulation controller that controls the water temperature regulation apparatus. The water temperature regulation controller can adjust the degree of superheating or the degree of supercooling in accordance with each of the modes, to thereby adjust a degree of opening of the expansion valve.
When the second mode is selected, the operation is performed in the state where the target pressure of the refrigerant is set in accordance with operation setting conditions of the indoor unit. Hence, an excessive pressure may be applied to the refrigerant in the water temperature regulation apparatus. Consequently, in such a case, the water temperature regulation controller adjusts the degree of opening of the expansion valve, whereby the degree of superheating or the degree of supercooling of the refrigerant supplied to the water heat exchanger can be appropriately adjusted. Similarly in this manner, a waste of energy is suppressed, leading to an efficient operation.
On this occasion, in the second-1 mode in which the indoor air conditioning by the indoor unit is prioritized, in order to maintain the capability of the water heat exchanger around 100% of its designed capability, the water temperature regulation controller may adjust the degree of opening of the expansion valve in a direction in which the temperature difference of the water between the entrance side and the exit side of the water heat exchanger matches with the temperature difference when the capability of the water heat exchanger is exerted at 100% of its designed capability.
In the second-2 mode in which the water temperature regulation by the water temperature regulation apparatus is prioritized, the water temperature regulation controller may adjust the degree of opening of the expansion valve so as to make the maximum use of the water heat exchanger, regardless of its designed capability.
Further, the water temperature regulation apparatus includes: a bypass that connects an entrance portion and an exit portion of the water heat exchanger; a water control valve that adjusts a flow rate of the water in the bypass; and a water temperature regulation controller that controls the water temperature regulation apparatus. The water temperature regulation controller can also adjust a degree of opening of the water control valve, when the second-1 mode is selected by the outdoor controller.
When the second mode is selected, in the case where the target water temperature of the water temperature regulation apparatus is set so as to fall much below 100% of its designed capability, sufficient control may not be performed by only the above-mentioned adjustment of the degree of opening of the expansion valve. Consequently, in such a case, the water temperature regulation controller adjusts the degree of opening of the water control valve, whereby the flow rate of the water in the bypass is adjusted, and the mix ratio thereof to the water that is subjected to heat exchange by the water heat exchanger is changed. In this way, the temperature of the water can be regulated.
Such adjustment of the degree of opening of the water control valve leads to an expansion of the lower limit of the capability that can be adjusted for the water temperature regulation apparatus. With the use in combination with the above-mentioned adjustment of the degree of opening of the expansion valve, the degree of opening of the expansion valve can be adjusted in an adjustable range of the degree of opening of the expansion valve, and the degree of opening of the water control valve can be adjusted outside of the adjustable range of the degree of opening thereof. In this manner, an adjustment range of the capability exerted by the water heat exchanger can be expanded.

{Advantageous Effects of Invention}

According to the present invention, in accordance with various situations, one of the indoor unit and the water temperature regulation apparatus can be prioritized, leading to an operation with a high degree of freedom. Further, in accordance with operation states of the indoor unit and the water temperature regulation apparatus, a waste of energy is suppressed, leading to an efficient operation.

{Brief Description of Drawings}

{Fig. 1}
Fig. 1 is a diagram illustrating an overall configuration of a multi-type air conditioner according to the present invention.
{Fig. 2}
Fig. 2 is a diagram illustrating a configuration of a water temperature regulation apparatus in the multi-type air conditioner according to the present invention.
{Fig. 3}
Fig. 3 is a flow chart showing control of water temperature regulation in the multi-type air conditioner according to the present invention.
{Fig. 4}
Fig. 4 is a diagram illustrating an example map for determining a change amount in degree of opening of a water control valve in the multi-type air conditioner according to the present invention.
{Fig. 5}
Fig. 5 is a diagram illustrating another application example of the multi-type air conditioner according to the present invention.

{Description of Embodiments}

Hereinafter, an embodiment of the present invention is described with reference to the drawings.
As illustrated in Fig. 1, in a multi-type air conditioner 1, a plurality of indoor units 3A, 3B and a water temperature regulation apparatus 40 are connected in parallel with each other to one outdoor unit 2 between a gas-side pipe 4 and a liquid-side pipe 5 drawn from the outdoor unit 2.
The outdoor unit 2 includes: an inverter-driven compressor 10 that compresses a refrigerant; an oil separator 11 that separates lubricant oil from a gas refrigerant; a four-way selector valve 12 that makes switching among circulation directions of the refrigerant; an outdoor heat exchanger 13 that performs heat exchange between the refrigerant and an outdoor heat source such as outdoor air; a supercooling coil 14 configured integrally with the outdoor heat exchanger 13; an outdoor expansion valve (EEVH) 15; a reservoir 16 that stores a liquid refrigerant therein; a supercooling heat exchanger 17 that supercools the liquid refrigerant; an expansion valve for supercooling (EEVSC) 18 that controls the amount of refrigerant whose flow is to be branched into the supercooling heat exchanger 17; an accumulator 19 that separates a liquid component from the gas refrigerant to be suctioned by the compressor 10 and enables the compressor 10 to suction only a gas component; a gas-side operation valve 20; and a liquid-side operation valve 21.
The above-mentioned elements of the outdoor unit 2 are connected by a refrigerant pipe 22 according to a known method, and form an outdoor refrigerant circuit 23. The outdoor unit 2 also includes an oil returning circuit 25 between the oil separator 11 and a suction pipe of the compressor 10, and the oil returning circuit 25 returns the lubricant oil that is separated from the discharged gas refrigerant by the oil separator 11, to the compressor 10 by a predetermined amount.
The outdoor unit 2 further includes an outdoor controller 26, and the outdoor controller 26 controls the compressor 10, the four-way selector valve 12, the outdoor expansion valve (EEVH) 15, the expansion valve for supercooling (EEVSC) 18, and the like.
The gas-side pipe 4 and the liquid-side pipe 5 are refrigerant pipes that are respectively connected to the gas-side operation valve 20 and the liquid-side operation valve 21 of the outdoor unit 2. With this configuration, a sealed one-system refrigerant circuit 7 is formed.
The indoor units 3A, 3B each include: an indoor heat exchanger 30 that performs heat exchange between indoor air and the refrigerant, for indoor air conditioning; and an indoor expansion valve (EEVC) 31. The indoor units 3A, 3B are connected to the gas-side pipe 4 and the liquid-side pipe 5 through indoor branched gas- side pipes 4A, 4B and indoor branched liquid- side pipes 5A, 5B, respectively. The indoor units 3A, 3B also each include an indoor controller 33 that controls the indoor expansion valve (EEVC) 31 and the like. Note that the indoor controller 33 of each indoor unit 3A, 3B is connected to the outdoor controller 26.
An air cooling operation of the multi-type air conditioner 1 described above is performed in the following manner.
From the high-temperature high-pressure gas refrigerant compressed and discharged by the compressor 10, lubricant oil contained in the refrigerant is separated by the oil separator 11. After that, the gas refrigerant is fed to the outdoor heat exchanger 13 by the four-way selector valve 12, and is subjected to heat exchange with the outdoor air by the outdoor heat exchanger 13, to be thereby condensed and liquefied. Note that, at the time of the air cooling operation, the speed of the compressor 10 is controlled by the outdoor controller 26 such that a low pressure of the refrigerant is the target value. The resultant liquid refrigerant is further cooled by the supercooling coil 14, then passes through the outdoor expansion valve 15, and is once stored in the reservoir 16.
The liquid refrigerant whose amount of circulation has been adjusted by the reservoir 16 passes through the supercooling heat exchanger 17, and is circulated in the liquid refrigerant pipe. At this time, the liquid refrigerant is subjected to heat exchange with the refrigerant whose flow is branched from the liquid refrigerant pipe and which is adiabatically expanded by the expansion valve for supercooling (EEVSC) 18, so that a degree of supercooling is given to the liquid refrigerant. The liquid refrigerant passes through the liquid-side operation valve 21, and is guided out of the outdoor unit 2 into the liquid-side pipe 5. Moreover, the flow of the liquid refrigerant guided out into the liquid-side pipe 5 is branched into the respective branched liquid- side pipes 5A, 5B of the indoor units 3A, 3B.
The liquid refrigerant whose flow is branched into each branched liquid- side pipe 5A, 5B flows into each indoor unit 3A, 3B, is adiabatically expanded by the indoor expansion valve (EEVC) 31, and flows as a gas-liquid two-phase flow into the indoor heat exchanger 30. In the indoor heat exchanger 30, heat exchange is performed between the indoor air and the refrigerant, and the indoor air is thus cooled to be used for indoor air cooling. Meanwhile, the refrigerant is gasified, passes through each branched gas- side pipe 4A, 4B, and joins the gas refrigerants from the other indoor units, in the gas-side pipe 4. Note that, at the time of the air cooling operation, in the indoor units 3A, 3B, the degree of opening of the indoor expansion valve (EEVC) 31 is controlled by the indoor controller 33 such that the degree of refrigerant exit superheating of the indoor heat exchanger 30 that functions as an evaporator is the target value.
The gas refrigerant joined together in the gas-side pipe 4 returns again to the outdoor unit 2, passes through the gas-side operation valve 20 and the four-way selector valve 12, joins the gas refrigerant from the supercooling heat exchanger 17, and is then introduced into the accumulator 19. The liquid component contained in the gas refrigerant is separated by the accumulator 19, and only the gas component is suctioned by the compressor 10. The suctioned refrigerant is compressed again by the compressor 10. The air cooling operation is performed through repetition of the above-mentioned cycle.
Meanwhile, an air heating operation is performed in the following manner.
From the high-temperature high-pressure gas refrigerant compressed and discharged by the compressor 10, lubricant oil contained in the refrigerant is separated by the oil separator 11. After that, the gas refrigerant is fed to the gas-side operation valve 20 by the four-way selector valve 12. Note that, at the time of the air heating operation, the speed of the compressor 10 is controlled by the outdoor controller 26 such that a high pressure of the refrigerant is the target value. The refrigerant fed to the gas-side operation valve 20 is guided out of the outdoor unit 2 through the gas-side pipe 4, and is introduced into the plurality of indoor units 3A, 3B through the indoor branched gas- side pipes 4A, 4B.
The high-temperature high-pressure gas refrigerant introduced into the indoor unit 3A, 3B is subjected to heat exchange with the indoor air by the indoor heat exchanger 30, and the indoor air is thus heated to be used for indoor air heating. The liquid refrigerant condensed by the indoor heat exchanger 30 passes through the indoor expansion valve 31 and the branched liquid- side pipe 5A, 5B, joins the refrigerants from the other indoor units, and is then returned to the outdoor unit 2 through the liquid-side pipe 5. Note that, at the time of the air heating operation, in the indoor units 3A, 3B, the degree of opening of the indoor expansion valve 31 is controlled by the indoor controller 33 such that the refrigerant exit temperature or the degree of refrigerant supercooling of the indoor heat exchanger 30 that functions as a condenser is the target value.
The refrigerant returned to the outdoor unit 2 reaches the supercooling heat exchanger 17 through the liquid-side operation valve 21, and is supercooled similarly to the air cooling operation. After that, the refrigerant flows into the reservoir 16, and is once stored therein, whereby the amount of circulation thereof is adjusted. The resultant liquid refrigerant is supplied to the outdoor expansion valve (EEVH) 15 to be adiabatically expanded, and then flows into the outdoor heat exchanger 13 through the supercooling coil 14.
Heat exchange is performed between the outdoor air and the refrigerant by the outdoor heat exchanger 13, and the refrigerant absorbs heat from the outdoor air to be evaporated and gasified. The resultant refrigerant passes through the four-way selector valve 12 from the outdoor heat exchanger 13, joins the gas refrigerant from the supercooling heat exchanger 17, and is then introduced into the accumulator 19. The liquid component contained in the gas refrigerant is separated by the accumulator 19, and only the gas component is suctioned by the compressor 10. The suctioned refrigerant is compressed again by the compressor 10. The air heating operation is performed through repetition of the above-mentioned cycle.
As illustrated in Fig. 2, the water temperature regulation apparatus 40 regulates the temperature of water used by water utilizing equipment, and includes a water temperature regulation unit 50, a water temperature regulation tank 60, and a water temperature regulation controller 45 that is connected to the outdoor controller 26 and controls the elements of the water temperature regulation apparatus 40.
The water temperature regulation unit 50 and the water temperature regulation tank 60 are connected to each other by water pipes 61, 62, and a pump 63 provided to the water pipe 62 circulates water through the water pipes 61, 62 between the water temperature regulation unit 50 and the water temperature regulation tank 60. With this configuration, a sealed one-system water circuit 64 is formed.
The water temperature regulation unit 50 includes: a water heat exchanger 51; an expansion valve (EEV) 52 provided to a branched liquid-side pipe 5C branched from the liquid-side pipe 5; and a bypass pipe 53 that connects a branched gas-side pipe 4C branched from the gas-side pipe 4 and the branched liquid-side pipe 5C branched from the liquid-side pipe 5, to thereby bypass the water heat exchanger 51.
The water heat exchanger 51 is formed of, for example, a plate heat exchanger, and performs heat exchange between: a channel Ch1 that connects the branched gas-side pipe 4C and the branched liquid-side pipe 5C in the multi-type air conditioner 1 (refrigerant circuit 7); and a channel Ch2 that connects the water pipe 61 and the water pipe 62 in the water utilizing equipment (water circuit 64).
The channel Ch2 of the water heat exchanger 51 is provided with a water temperature sensor 65 or a thermistor 66 that detects the entrance water temperature thereof and a water temperature sensor 67 or a thermistor 68 that detects the exit water temperature thereof.
The water temperature regulation tank 60 includes a heat exchanger 71 inside of a tank 70. The heat exchanger 71 performs heat exchange between water in the tank 70 and water in the water circuit 64, to thereby heat or cool the water in the tank 70 and regulate the temperature thereof. The temperature-regulated water in the tank 70 is sent out to the water utilizing equipment to be used for intended purposes such as floor heating and air heating.
Further, a bypass 72 and a water control valve 73 are provided between the water pipes 61, 62. A connection portion between the bypass 72 and the water pipe 61 is provided with a sensor 74 that detects the exit water temperature thereof.
In the multi-type air conditioner 1 including the water temperature regulation apparatus 40 configured as described above, the outdoor controller 26 and the water temperature regulation controller 45 work in cooperation with each other, whereby the operation is controlled according to a flow as shown in Fig. 3.
In the operation of the water temperature regulation apparatus 40, first, the outdoor controller 26 acquires information on operation states from the respective indoor controllers 33 of the other indoor units 3A, 3B and the water temperature regulation controller 45 of the water temperature regulation apparatus 40 (Step S101).
As a result, if all the other indoor units 3A, 3B do not perform the air cooling operation or the air heating operation and if the water temperature regulation apparatus 40 is operated alone, the transition is made to a single operation mode (Steps S102 and S103).

In the single operation mode of the water temperature regulation apparatus 40, the outdoor controller 26 acquires, from the water temperature regulation controller 45, information on a target exit water temperature (set temperature) T1 that is set to the water temperature regulation controller 45 by a user. The outdoor controller 26 also acquires, from the water temperature regulation controller 45, information on an exit water temperature To of the water heat exchanger 51 detected by the thermistor 68.
Then, on the basis of the acquired target exit water temperature T1 and the actual exit water temperature To, a target pressure P1 in the refrigerant circuit 7 of the outdoor unit 2 is set (corrected) such that the exit water temperature To approaches the target exit water temperature T1. Here, in the case where the water temperature regulation apparatus 40 performs a heating operation, the target pressure P1 is set to a high pressure side of the refrigerant circuit 7. In the case where the water temperature regulation apparatus 40 performs a cooling operation, the target pressure P1 is set to a low pressure side of the refrigerant circuit 7.
Specifically, for example, in the case where the water temperature regulation apparatus 40 performs the heating operation,
if the exit water temperature To > the target exit water temperature T1, the target pressure P1 in the refrigerant circuit 7 is decreased, and
if the exit water temperature To < the target exit water temperature T1, the target pressure P1 in the refrigerant circuit 7 is increased.
On the other hand, in the case where the water temperature regulation apparatus 40 performs the cooling operation,
if the exit water temperature To > the target exit water temperature T1, the target pressure P1 in the refrigerant circuit 7 is decreased, and
if the exit water temperature To < the target exit water temperature T1, the target pressure P1 in the refrigerant circuit 7 is increased.
Such sampling of the target exit water temperature T1 and the exit water temperature To as described above is repeated at regular time intervals, and the target pressure P1 is adjusted until a difference between the target exit water temperature T1 and the exit water temperature To becomes a prescribed value (for example, 0 degrees) set in advance. Specifically, the target exit water temperature T1 is regulated by the following start-stop operation. That is, when the target pressure is adjusted, in the case where the exit water temperature To becomes lower (at the time of the air cooling operation) and higher (at the time of the air heating operation) by the prescribed value or more than the target exit water temperature T1 continuously for a prescribed length of time or more, the operation of the water temperature regulation apparatus 40 is stopped. If the temperature difference becomes smaller, the operation thereof is restarted.
If such control as described above is performed at the time of the single operation of the water temperature regulation apparatus 40, the target pressure P1 of the refrigerant in the refrigerant circuit 7 of the outdoor unit 2 can be lower (at the time of the air heating operation) and higher (at the time of the air cooling operation), compared with the case where the indoor units 3A, 3B perform the air cooling operation or the air heating operation. Accordingly, the outdoor unit 2 can perform an energy-saving operation.
Further, if the outdoor unit 2 simply adjusts the target pressure P1 in the entire refrigerant circuit 7, the water temperature regulation unit 50 can achieve the adjustment of the degree of superheating (at the time of the air cooling operation) and the degree of supercooling (at the time of the air heating operation) by adjusting the degree of opening of the expansion valve 52, so as to make the maximum use of the capability of the water heat exchanger 51. Accordingly, the water temperature regulation unit 50 can perform an efficient operation.
Meanwhile, in Steps S101 and S102, if at least one of the other indoor units 3A, 3B performs the air cooling operation or the air heating operation, the transition is made to a mixed operation mode (Step S104).

In the mixed operation mode, the outdoor controller 26 acquires, from each of the indoor controller 33 and the water temperature regulation controller 45 of the water temperature regulation apparatus 40, information on the operation state thereof. Then, similarly to a normal multi-type air conditioner not including the water temperature regulation apparatus 40, the target pressure P1 in the refrigerant circuit 7 of the outdoor unit 2 is set as appropriate in accordance with the set temperature in each indoor unit 3A, 3B.
Then, the outdoor controller 26 sends a signal indicating that a mixed operation is currently performed, to the water temperature regulation controller 45.
Upon the reception of this signal, the water temperature regulation controller 45 checks which of an "air conditioning priority mode (second-1 mode)" by each indoor unit 3A, 3B and a "water temperature regulation priority mode (second-2 mode)" by the water temperature regulation controller 45 is set in the entire system of the multi-type air conditioner 1 (Steps S105 and S106).

"Capability 100% Maintaining Operation"

As a result, if the "air conditioning priority mode" is set, the target pressure P1 in the refrigerant circuit 7 of the outdoor unit 2 is set in accordance with the set temperature of each indoor unit 3A, 3B, and hence the refrigerant pressure is more than necessary in the water heat exchanger 51 of the water temperature regulation unit 50. Accordingly, the water temperature regulation controller 45 makes the transition to a capability 100% maintaining operation, in which the capability of the water heat exchanger 51 does not become equal to or more than 100% and is maintained around 100% (Step S107). In the capability 100% maintaining operation, the degree of opening of the expansion valve 52 is controlled, and the degree of superheating (at the time of the air cooling operation) or the degree of supercooling (at the time of the air heating operation) is adjusted, whereby the capability of the water heat exchanger 51 does not become equal to or more than 100% and is maintained around 100%.
Specifically, the water temperature regulation controller 45 acquires information on an entrance water temperature Ti and the exit water temperature To of the water heat exchanger 51 detected by the thermistor 66, 68. Then, the absolute value of a temperature difference ΔT between the entrance water temperature Ti and the exit water temperature To is controlled so as not to become equal to or more than a prescribed value set in advance at which the capability of the water heat exchanger 51 becomes 100%. For example, in the case of the water heat exchanger 51 in which the temperature difference between the entrance side and the exit side is X degrees in its capability 100% state, the degree of opening of the expansion valve 52 is controlled such that the absolute value of the temperature difference ΔT between the detected entrance water temperature Ti and the detected exit water temperature To falls within X degrees.
A specific example based on the above-mentioned example is given. For example, in the case where the water temperature regulation apparatus 40 performs the cooling operation, as a result of monitoring of the entrance water temperature Ti and the exit water temperature To at regular intervals,
if the entrance water temperature Ti - the exit water temperature To ≥ (X + 0.5) degrees, the degree of opening of the expansion valve 52 is reduced, and the target degree of superheating of the refrigerant in the channel Ch1 is increased by a predetermined value (for example, 1 degree), and
if the entrance water temperature Ti - the exit water temperature To ≤ (X - 0.5) degrees, the degree of opening of the expansion valve 52 is increased, and the target degree of superheating of the refrigerant in the channel Ch1 is reduced by a predetermined value (for example, 1 degree).
On the other hand, in the case where the water temperature regulation apparatus 40 performs the heating operation,
if the exit water temperature To - the entrance water temperature Ti ≥ (X + 0.5) degrees, the degree of opening of the expansion valve 52 is reduced, and the target degree of supercooling of the refrigerant in the channel Ch1 is increased by a predetermined value (for example, 1 degree), and
if the exit water temperature To - the entrance water temperature Ti ≤ (X - 0.5) degrees, the degree of opening of the expansion valve 52 is increased, and the target degree of supercooling of the refrigerant in the channel Ch1 is reduced by a predetermined value (for example, 1 degree).
As described above, at the time of the mixed operation, the target pressure P1 in the refrigerant circuit 7 of the outdoor unit 2 is set in accordance with the set temperature of each indoor unit 3A, 3B, and hence the refrigerant pressure is more than necessary in the water heat exchanger 51 of the water temperature regulation unit 50. In this case, if the capability of the water heat exchanger 51 is controlled so as not to become equal to or more than 100%, such an operation that prioritizes indoor air conditioning by the indoor unit 3A, 3B can be performed, while an excessive capability of the water temperature regulation apparatus 40 and an insufficient capability of the indoor unit 3A, 3B are avoided.

"Capability Suppressing Operation Performed by Adjusting Degree of Opening of Expansion Valve 52"

Further, the water temperature regulation controller 45 can make the transition to a capability suppressing operation, in the case where the difference between the target exit water temperature T1 set by the user and the entrance water temperature Ti is equal to or less than X degrees that is the difference between the entrance side and the exit side in the capability 100% state of the water heat exchanger 51. In the capability suppressing operation, the degree of opening of the expansion valve 52 is further adjusted, and the operation is controlled in the state where the capability of the water heat exchanger 51 is suppressed to be less than 100% (Steps S108 and S109).
Specifically, for example, in the case where the water temperature regulation apparatus 40 performs the cooling operation, if the relation that (X - 2) degrees ≤ the entrance water temperature Ti - the target exit water temperature T1 < X degrees is satisfied, the transition is made to the below-100% suppressing operation.
If the target exit water temperature T1 - the exit water temperature To ≥ 0.5 degrees, the degree of opening of the expansion valve 52 is reduced, and the target degree of superheating of the refrigerant in the channel Ch1 is increased by a predetermined value (for example, 1 degree), and
if the target exit water temperature T1 - the exit water temperature To < -0.5 degrees, the degree of opening of the expansion valve 52 is increased, and the target degree of superheating of the refrigerant in the channel Ch1 is reduced by a predetermined value (for example, 1 degree).
On the other hand, in the case where the water temperature regulation apparatus 40 performs the heating operation, if the relation that (X - 2) degrees ≤ the target exit water temperature T1 - the entrance water temperature Ti < X degrees is satisfied, the transition is made to the below-100% suppressing operation.
If the exit water temperature To - the target exit water temperature T1 ≥ 0.5 degrees, the degree of opening of the expansion valve 52 is reduced, and the target degree of supercooling of the refrigerant in the channel Ch1 is increased by a predetermined value (for example, 1 degree), and
if the exit water temperature To - the target exit water temperature T1 ≤ -0.5 degrees, the degree of opening of the expansion valve 52 is increased, and the target degree of supercooling of the refrigerant in the channel Ch1 is reduced by a predetermined value (for example, 1 degree).
As described above, in the case where the difference between the target exit water temperature T1 set by the user and the exit water temperature To is small, the capability of the water heat exchanger 51 of the water temperature regulation unit 50 is controlled by the expansion valve 52 so as to be suppressed to be less than 100%, whereby the lower limit of the capability that can be adjusted for the water temperature regulation apparatus 40 can be expanded even without the water control valve 73 to be described later.

"Capability Below-100% Suppressing Operation Performed by Adjusting Degree of Opening of Water Control Valve 73"

In the case where the amount of adjustment of the degree of opening of the expansion valve 52 reaches its limit as a result of the above-mentioned capability below-100% suppressing operation performed by adjusting the degree of opening of the expansion valve 52 and where further adjustment thereof cannot be performed, the degree of opening of the water control valve 73 is adjusted, whereby the operation can also be controlled in the state where the capability of the water heat exchanger 51 is suppressed to be less than 100% (Steps S110 and S111). If the degree of opening of the water control valve 73 is changed, the amount of water that bypasses the water heat exchanger 51 through the bypass 72 can be adjusted, and the temperature of water supplied to the heat exchanger 71 of the water temperature regulation tank 60 can be adjusted, after a connection portion between the bypass 72 and the water pipe 62
A specific example thereof is given. For example, the degree of opening of the water control valve 73 is controlled such that the exit water temperature To = the target exit water temperature T1.
For the adjustment of the degree of opening of the water control valve 73, the water temperature regulation controller 45 stores therein such a map as illustrated in Fig. 4, the map indicating the correlation between: a temperature difference ΔT2 between the target exit water temperature T1 and the exit water temperature To during the operation (at the time of the heating operation, ΔT2 = the target exit water temperature T1 - the exit water temperature To; at the time of the cooling operation, ΔT2 = the exit water temperature To - the target exit water temperature T1); and a change amount in degree of opening ΔP of the water control valve 73. The change amount in degree of opening ΔP of the water control valve 73 may be determined on the basis of this map, and the adjustment of the degree of opening of the water control valve 73 may be controlled.
In this way, in the case where sufficient control cannot be performed by only adjusting the degree of opening of the expansion valve 52, the amount of water passing through the bypass 72 is adjusted by the water control valve 73, whereby the lower limit of the capability that can be adjusted for the water temperature regulation apparatus 40 can be further expanded.
Meanwhile, in Step S106, if the "water temperature regulation priority mode" by the water temperature regulation controller 45 is set in the entire system of the multi-type air conditioner 1, the water temperature regulation controller 45 acquires information on the entrance water temperature Ti and the exit water temperature To of the water heat exchanger 51. Then, a water temperature regulation priority operation can be performed such that the absolute value of the temperature difference ΔT between the entrance water temperature Ti and the exit water temperature To approaches the target exit water temperature T1 even if the capability of the water heat exchanger 51 becomes equal to or more than 100% (Step S112).
Specifically, the water temperature regulation controller 45 acquires information on the entrance water temperature Ti and the exit water temperature To of the water heat exchanger 51 detected by the thermistor 66, 68. Then, in the water heat exchanger 51 in which the temperature difference between the entrance side and the exit side is X degrees in its capability 100% state, even if the absolute value of the temperature difference ΔT between the entrance water temperature Ti and the exit water temperature To becomes equal to or more than X degrees, the degrees of opening of the expansion valve 52 and the water control valve 73 are not adjusted, and the operation is continued such that the exit water temperature To approaches the target exit water temperature T1.
In this way, also in the mixed operation mode, the water temperature regulation apparatus 40 can be prioritized, and the usage range can be expanded by an appropriate selection depending on an intended purpose and the like of the user.
As described above, flexible control suited to requirements in respective operations of the indoor units 3A, 3B and the water temperature regulation apparatus 40 can be performed in accordance with respective operation conditions thereof, leading to an efficient operation. As a result, energy can be saved by making efficient use of the energy.
Further, the operation can be performed in the state where the target pressure of the refrigerant is set to a level matched with the indoor units 3A, 3B. Hence, even in the case where the water temperature regulation apparatus 40 is additionally provided to an existing multi-type air conditioner not including the water temperature regulation apparatus 40, the water temperature regulation apparatus 40 can be easily provided thereto without the need to change basic control in the indoor units 3A, 3B.
Note that, in the above-mentioned embodiment, the number of the provided water temperature regulation apparatuses 40 is only one, but may be more than one.
In this configuration, in the case where the other indoor units 3A, 3B do not perform the air heating operation or the air cooling operation, where only the plurality of water temperature regulation apparatuses 40 perform the water temperature regulating operation, and where the target exit water temperature T1 is different among the plurality of water temperature regulation apparatuses 40, control similar to that in the above-mentioned single operation mode of the water temperature regulation apparatus 40 is carried out so as to follow the highest-load water temperature regulation apparatus 40 in which the absolute value of the difference between the target exit water temperature T1 and the actual exit water temperature To is largest.
Meanwhile, in the case where the other indoor units 3A, 3B perform the air heating operation or the air cooling operation, the water temperature regulation controller 45 of each of the plurality of water temperature regulation apparatuses 40 carries out control similar to that in the above-mentioned mixed operation mode.

(Other Application Examples)

Further, the configuration of the multi-type air conditioner 1 is not limited to the configuration exemplified above, and may be other configurations.
For example, the present invention can be similarly applied to such a multi-type air conditioner 1' as illustrated in Fig. 5. In the multi-type air conditioner 1', the outdoor unit 2, a plurality of indoor units 3A, 3B, 3C, and the water temperature regulation apparatus 40 are connected to each other by a high-pressure gas pipe 57, a low-pressure gas pipe 59, and the liquid-side pipe 5, and the plurality of indoor units 3A, 3B, 3C and the water temperature regulation apparatus 40 can mixedly perform the air cooling operation and the air heating operation.
In the multi-type air conditioner 1' configured as described above, the outdoor unit 2 includes a plurality of, for example, two four-way selector valves 12. Each four-way selector valve 12 has: one port connected to the high-pressure gas pipe 57 located in the outdoor unit 2; another port connected to the outdoor heat exchanger 13; still another port that is connected to the low-pressure gas pipe 59 by a branched low-pressure gas pipe 87; and the other port that is connected to the branched low-pressure gas pipe 87 through a strainer and a capillary tube.
Further, in the multi-type air conditioner 1', the indoor units 3A, 3B, 3C and the water temperature regulation apparatus 40 each include a branched-flow controller 95 that makes switching between the high-pressure gas pipe 57 and the low-pressure gas pipe 59.
The branched-flow controller 95 includes: an indoor four-way valve 97 that makes switching between connection of the high-pressure gas pipe 57 and the indoor heat exchanger 30 and connection of the low-pressure gas pipe 59 and the indoor heat exchanger 30; and a high-pressure low-pressure bypass pipe 99 that connects the high-pressure gas pipe 57 and the low-pressure gas pipe 59.
An air cooling/heating operation of the multi-type air conditioner 1' described above is performed in the following manner.
The high-temperature high-pressure gas refrigerant compressed by the compressor 10 is discharged into the high-pressure gas pipe 57, and is sent to the indoor units 3A, 3B, 3C and the water temperature regulation apparatus 40.
Further, part of the high-temperature high-pressure gas refrigerant discharged into the high-pressure gas pipe 57 is branched to be sent to the outdoor heat exchanger 13 through the four-way selector valve 12, and is subjected to heat exchange with the outdoor air by the outdoor heat exchanger 13, to be thereby condensed and liquefied into a liquid refrigerant.
This liquid refrigerant passes through the outdoor expansion valve 15, and is once stored in the reservoir 16, where the amount of circulation thereof is adjusted.
The liquid refrigerant from the reservoir 16 is subjected to heat exchange with the refrigerant adiabatically expanded by the electronic expansion valve for supercooling (EEVSC) 18, while passing through the supercooling heat exchanger 17, so that the liquid refrigerant is cooled to a predetermined degree of supercooling.
The liquid refrigerant to which the predetermined degree of supercooling is given is guided out of the outdoor unit 2 into the liquid-side pipe 5.
In the indoor units 3A, 3B, 3C and the water temperature regulation apparatus 40, at the time of the air heating operation, the high-pressure gas pipe 57 and the indoor heat exchanger 30 are connected to each other by operating the indoor four-way valve 97, and the high-temperature high-pressure gas refrigerant is introduced from the high-pressure gas pipe 57 into the indoor heat exchanger 30.
The introduced high-temperature high-pressure gas refrigerant is subjected to heat exchange with the indoor air by the indoor heat exchanger 30, and the indoor air is thus heated to be used for indoor air heating.
Meanwhile, the gas refrigerant is cooled by the indoor air to be condensed and liquefied into a liquid refrigerant, and the liquid refrigerant flows into the liquid-side pipe 5 through the indoor electronic expansion valve (EEVC) 31.
At the time of the air cooling operation, the low-pressure gas pipe 59 and the indoor heat exchanger 30 are connected to each other by operating the indoor four-way valve 97.
The liquid refrigerant that flows in from the liquid-side pipe 5 is adiabatically expanded by the indoor electronic expansion valve (EEVC) 31, and flows as a gas-liquid two-phase flow into the indoor heat exchanger 30.
Heat exchange is performed between the indoor air and the refrigerant by the indoor heat exchanger 30, and the indoor air is thus cooled to be used for indoor air cooling.
Meanwhile, the refrigerant is gasified, and is guided out into the low-pressure gas pipe 59 to be returned to the outdoor unit 2.
In the multi-type air conditioner 1', some of the plurality of indoor units 3A, 3B, 3C may perform the air cooling operation, and, at the same time, some of the plurality of indoor units 3A, 3B, 3C may perform the air heating operation. In such a case, when the water temperature regulation apparatus 40 regulates the water temperature, such mixed operations of the indoor units 3A, 3B, 3C are determined for each of the air cooling operation and the air heating operation. For example, when all of the plurality of indoor units 3A, 3B, 3C perform the air cooling operation, if the water temperature regulation apparatus 40 performs the cooling operation, control similar to that in the above-mentioned mixed operation mode may be performed, and if the water temperature regulation apparatus 40 performs the heating operation, control similar to that in the above-mentioned single operation mode may be performed.
Note that the present invention is not limited to the above-mentioned embodiment, and can be modified as appropriate within a range not departing from the scope thereof.
For example, the target exit water temperature T1, the entrance water temperature Ti, and the exit water temperature To are used as parameters detected for the adjustment of the degrees of opening of the expansion valve 52 and the water control valve 73, but other parameters may be adopted as appropriate as long as similar control can be performed.
Further, others than the above-mentioned method may be used as the method of adjusting the degrees of opening of the expansion valve 52 and the water control valve 73 on the basis of the detected parameters such that the actual water temperature approaches the target exit water temperature T1.
Moreover, in the above-mentioned embodiment, the plurality of modes for water temperature regulation are described, but all of the modes do not necessarily need to be provided, and part thereof may be omitted. Further, if the operation in the plurality of modes can be performed similarly to the above as a whole, the order of control and the like may be changed as appropriate.

{Reference Signs List}

1: multi-type air conditioner
2: outdoor unit
3A, 3B, 3C: indoor unit
4: gas-side pipe
4A, 4B, 4C: branched gas-side pipe
5: liquid-side pipe
5A, 5B, 5C: branched liquid-side pipe
7: refrigerant circuit
10: compressor
11: oil separator
12: four-way selector valve
13: outdoor heat exchanger
14: supercooling coil
15: outdoor expansion valve
16: reservoir
17: supercooling heat exchanger
19: accumulator
20: gas-side operation valve
21: liquid-side operation valve
22: refrigerant pipe
23: outdoor refrigerant circuit
25: circuit
26: outdoor controller
30: indoor heat exchanger
33: indoor controller
40: water temperature regulation apparatus
45: water temperature regulation controller
50: water temperature regulation unit
51: water heat exchanger
52: expansion valve
53: bypass pipe
57: high-pressure gas pipe
59: low-pressure gas pipe
60: water temperature regulation tank
61, 62: water pipe
63: pump
64: water circuit
65, 67: water temperature sensor
66, 68: thermistor
70: tank
71: heat exchanger
72: bypass
73: water control valve
74: sensor
87: branched low-pressure gas pipe
95: branched-flow controller
97: indoor four-way valve
99: high-pressure low-pressure bypass pipe

Claims

A multi-type air conditioner comprising:
an outdoor unit (2) including an outdoor heat exchanger (13) that performs heat exchange between outdoor air and a refrigerant;

at least one indoor unit (3A, 3B, 3C) connected to the outdoor unit, the indoor unit including an indoor heat exchanger (30) that performs heat exchange between the refrigerant supplied from the outdoor unit and indoor air, to thereby condition the indoor air;

at least one water temperature regulation apparatus (40) that is connected to the outdoor unit (2) in parallel with the indoor unit (3A, 3B, 3C), the water temperature regulation apparatus including a water heat exchanger (71) that performs heat exchange between the refrigerant supplied from the outdoor unit and water, to thereby regulate a temperature of the water;

a refrigerant circuit (7) that circulates the refrigerant between: the outdoor unit (2); and the indoor unit (3A, 3B, 3C) and the water temperature regulation apparatus (40); and

an outdoor controller (26) that sets a target pressure of the refrigerant in the refrigerant circuit (7) and operates the outdoor unit (2) such that an actual pressure approaches the set target pressure, wherein

the outdoor controller (26) can make switching between: a first mode for an operation in which, when only the water temperature regulation apparatus (40) is operated, the target pressure of the refrigerant is set in accordance with a target water temperature set by the water temperature regulation apparatus; and a second mode for an operation in which, when the indoor unit (3A, 3B, 3C) and the water temperature regulation apparatus (40) are mixedly operated, the target pressure of the refrigerant is set in accordance with the indoor unit.
The multi-type air conditioner according to claim 1, wherein
in the second mode, a second-1 mode and a second-2 mode are selectable,
in the second-1 mode, the indoor air conditioning by the indoor unit (3A, 3B, 3C) is prioritized, and
in the second-2 mode, the water temperature regulation by the water temperature regulation apparatus (40) is prioritized.
The multi-type air conditioner according to claim 2,
wherein
the water temperature regulation apparatus (40) includes:
an expansion valve (52) that adjusts a degree of superheating or a degree of supercooling of the refrigerant supplied to the water heat exchanger (51); and

a water temperature regulation controller (45) that controls the water temperature regulation apparatus (40), and
the water temperature regulation controller (45) adjusts the degree of superheating or the degree of supercooling in accordance with each of the modes, to thereby adjust a degree of opening of the expansion valve (52).
The multi-type air conditioner according to claim 2 or 3,
wherein
the water temperature regulation apparatus (40) includes:
a bypass (72) that connects an entrance portion and an exit portion of the water heat exchanger (71);

a water control valve (73) that adjusts a flow rate of the water in the bypass (72); and

a water temperature regulation controller (45) that controls the water temperature regulation apparatus, and
the water temperature regulation controller (45) adjusts a degree of opening of the water control valve (73), when the second-1 mode is selected by the outdoor controller (26).