AIR CONDITIONER

Abstract

A refrigerant circuit performs a cool storage operation in which a thermal storage medium is circulated such that a refrigerant having been condensed in an air heat exchanger and passed through an auxiliary heat exchanger is evaporated in the thermal storage heat exchanger. In a thermal storage circuit during the cool storage operation of the refrigerant circuit, the thermal storage medium is circulated such that the thermal storage medium having flowed out from an outlet of a thermal storage tank sequentially passes through the auxiliary heat exchanger, a retention portion, and the thermal storage heat exchanger and flows into an inlet of the thermal storage tank. The retention portion retains crystals contained in the thermal storage medium.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2013-205695 filed on Sep. 30, 2013, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

Storing heat using thermal storage properties of a thermal storage medium, and utilizing the heat stored in the thermal storage medium for driving an air conditioner, for example, have been known. As an example of such a thermal storage medium, a thermal storage material which turns into slurry when cooled (e.g., a tetra-n-butyl ammonium bromide aqueous solution) has been known. For example, Japanese Unexamined Patent Publication No. 2013-083439 discloses an air conditioning system in which a thermal storage circuit is formed by connecting a thermal storage tank in which a thermal storage medium is stored, and a thermal storage heat exchanger incorporated in the refrigerant circuit. In this air conditioning system, a cool storage mode is performed in which a refrigerant is circulated in the refrigerant circuit such that the refrigerant condensed in a condenser is evaporated in the thermal storage heat exchanger, and in which the thermal storage medium is circulated in the thermal storage circuit such that the thermal storage medium having flowed out from an outlet of the thermal storage tank passes through the thermal storage heat exchanger and flows in an inlet of the thermal storage tank. In the cool storage mode, the thermal storage medium passing through the thermal storage heat exchanger turns into slurry by being cooled due to heat absorption effects of the refrigerant passing through the thermal storage heat exchanger, and thereafter flows in the inlet of the thermal storage tank. Cold thermal energy (i.e., energy for cooling) is stored in the thermal storage medium in this manner.

Further, Japanese Unexamined Patent Publication No. H10-185248 discloses a preheater which applies heat to cold water having been transferred from an ice thermal storage tank via a cold water circulation pump, using a refrigerant flowing from a condenser to an expansion valve, in order to melt ice mixed in the cold water and discharge only cold water.

SUMMARY

According to an aspect of the present disclosure, an air conditioner includes: a refrigerant circuit having an air heat exchanger which exchanges heat between a refrigerant and air; a thermal storage circuit having a thermal storage tank configured to store a thermal storage medium which turns into slurry when cooled, and a circulation pump provided to circulate the thermal storage medium; a thermal storage heat exchanger which is connected to the refrigerant circuit and to the thermal storage circuit, and exchanges heat between the refrigerant flowing in the refrigerant circuit and the thermal storage medium flowing in the thermal storage circuit; an auxiliary heat exchanger which is connected to the refrigerant circuit and to the thermal storage circuit, and exchanges heat between the refrigerant flowing in the refrigerant circuit and the thermal storage medium flowing in the thermal storage circuit; and a retention portion provided in the thermal storage circuit to retain crystals contained in the thermal storage medium. The refrigerant circuit performs a cool storage operation in which the refrigerant is circulated such that the refrigerant which has been condensed in the air heat exchanger and passed through the auxiliary heat exchanger is evaporated in the thermal storage heat exchanger. In the thermal storage circuit during the cool storage operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from an outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into an inlet of the thermal storage tank.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a piping system diagram illustrating an example configuration of an air conditioner.

FIG. 2 is a schematic view illustrating an example configuration of a retention portion.

FIG. 3 is a piping system diagram illustrating a cool storage mode of the air conditioner.

FIG. 4 is a piping system diagram illustrating a first use cooling mode of the air conditioner.

FIG. 5 is a piping system diagram illustrating a second use cooling mode of the air conditioner.

FIG. 6 is a piping system diagram illustrating a simple cooling mode of the air conditioner.

FIG. 7 is a piping system diagram illustrating a simple heating mode of the air conditioner.

FIG. 8 is a graph illustrating a temperature change of a thermal storage medium in a thermal storage circuit.

FIG. 9 is a schematic view illustrating the first variation of the retention portion.

FIG. 10 is a schematic view illustrating the second variation of the retention portion.

FIG. 11 is a schematic view illustrating another variation of the retention portion.

FIG. 12 is a piping system diagram illustrating a variation of a refrigerant circuit.

DETAILED DESCRIPTION

Embodiments will be described in detail below with reference to the drawings. In the drawings, like reference characters have been used to designate identical or equivalent elements, and explanation thereof is not repeated.

[Air Conditioner]

FIG. 1 shows an example configuration of an air conditioner (1) according to an embodiment. The air conditioner (1) includes a refrigerant circuit (10), a thermal storage circuit (20), a thermal storage heat exchanger (30), an auxiliary heat exchanger (40), a retention portion (50), and a controller (100). The controller (100) is configured to control operation of the air conditioner (1), and controls each section of the refrigerant circuit (10) and the thermal storage circuit (20).

<Refrigerant Circuit>

The refrigerant circuit (10) is a closed circuit filled with a refrigerant, and performs a refrigeration cycle by circulating the refrigerant. In this example, the refrigerant circuit (10) includes a compressor (11), an outdoor heat exchanger (12), an outdoor expansion valve (13), an indoor expansion valve (14), an indoor heat exchanger (15), and a four-way switching valve (16). The compressor (11), the outdoor heat exchanger (12), the outdoor expansion valve (13), and the four-way switching valve (16) are provided in an outdoor unit (3). The indoor expansion valve (14) and the indoor heat exchanger (15) are provided in an indoor unit (4). An indoor fan (17) which transfers outdoor air to the outdoor heat exchanger (12) is provided in the outdoor unit (3), and an indoor fan (18) which transfers indoor air to the indoor heat exchanger (15) is provided in the indoor unit (4).

<<Compressor>>

The compressor (11) compresses the refrigerant and discharges the compressed refrigerant. Further, the compressor (11) is configured such that the number of rotations (i.e., an operation frequency) of the compressor (11) can be changed in response to control by the controller (100). For example, the compressor (11) includes a variable capacity compressor (e.g., rotary type, swing type, and scroll type compressors) capable of adjusting the number of rotations using an inverter circuit (not shown) controlled by the controller (100).

<<Outdoor Heat Exchanger>>

The outdoor heat exchanger (12) is an air heat exchanger which exchanges heat between the outdoor air transferred by the indoor fan (17) and the refrigerant. For example, the outdoor heat exchanger (12) includes a cross-fin type fin-and-tube heat exchanger.

<<Outdoor Expansion Valve>>

The outdoor expansion valve (13) adjusts the pressure of the refrigerant. The outdoor expansion valve (13) is capable of adjusting a degree of its opening in response to the control by the controller (100). For example, the outdoor expansion valve (13) includes an electronic expansion valve.

<<Indoor Expansion Valve>>

The indoor expansion valve (14) adjusts the pressure of the refrigerant. The indoor expansion valve (14) is capable of adjusting a degree of its opening in response to the control by the controller (100). For example, the indoor expansion valve (14) includes an electronic expansion valve.

<<Indoor Heat Exchanger>>

The indoor heat exchanger (15) is an air heat exchanger which exchanges heat between indoor air transferred by the indoor fan (18) and the refrigerant. For example, the indoor heat exchanger (15) includes a cross-fin type fin-and-tube heat exchanger.

<<Four-Way Switching Valve>>

The four-way switching valve (16) has first to fourth ports. The four-way switching valve (16) can be set to a first state (the state indicated by solid line in FIG. 1) and a second state (the state indicated by broken line in FIG. 1) in response to the control by the controller (100).

<Pipe Connection in Refrigerant Circuit>

In this example, the first port of the four-way switching valve (16) is connected to a discharge pipe of the compressor (11), and the third port of the four-way switching valve (16) is connected to a suction pipe of the compressor (11). Further, a gas-side end of the outdoor heat exchanger (12) and the fourth port of the four-way switching valve (16) are connected to each other by a first refrigerant pipe (P11). The liquid-side end of the outdoor heat exchanger (12) and the outdoor expansion valve (13) are connected to each other by a second refrigerant pipe (P12). The outdoor expansion valve (13) and the indoor expansion valve (14) are connected to each other by a third refrigerant pipe (P13). The indoor expansion valve (14) and a liquid-side end of the indoor heat exchanger (15) are connected to each other by a fourth refrigerant pipe (P14). A gas-side end of the indoor heat exchanger (15) and the second port of the four-way switching valve (16) are connected to each other by a fifth refrigerant pipe (P15). The auxiliary heat exchanger (40) is connected to the second refrigerant pipe (P12). The thermal storage heat exchanger (30) is connected to the third refrigerant pipe (P13).

Further, in this example, the refrigerant circuit (10) includes a first bypass pipe (PB1) and a second bypass pipe (PB2). One end of the first bypass pipe (PB1) is connected to an intermediate portion of the first refrigerant pipe (P11), and the other end is connected to a first intermediate portion (an intermediate portion located between the outdoor expansion valve (13) and the thermal storage heat exchanger (30)) of the third refrigerant pipe (P13). One end of the second bypass pipe (PB2) is connected to an intermediate portion of the fifth refrigerant pipe (P15), and the other end is connected to a second intermediate portion (an intermediate portion located between the thermal storage heat exchanger (30) and the indoor expansion valve (14)) of the third refrigerant pipe (P13).

<<Open/Close Valve and Pressure Relief Valve>>

In this example, a first open/close valve (V1), a second open/close valve (V2), a third open/close valve (V3), and a pressure relief valve (V4) are provided in the refrigerant circuit (10). Each of the open/close valves (V1, V2, V3) can be switched between an open state and a closed state in response to the control by the controller (100). The first open/close valve (V1) and the second open/close valve (V2) are disposed at the first bypass pipe (PB1) and the second bypass pipe (PB2), respectively. The third open/close valve (V3) is disposed between the second intermediate portion (i.e., the intermediate portion at which the end of the second bypass pipe (PB2) is connected) of the third refrigerant pipe (P13) and the indoor expansion valve (14). The pressure relief valve (V4) is connected in parallel with the third open/close valve (V3). When the pressure of the refrigerant on the side of the third open/close valve (V3) closer to the indoor expansion valve (14) exceeds a predetermined value, the pressure relief valve (V4) is opened to allow the refrigerant to flow from the outdoor expansion valve (13) side to the thermal storage heat exchanger (30) side.

<Thermal Storage Circuit>

The thermal storage circuit (20) is a closed circuit filled with a thermal storage medium, and stores heat by circulating the thermal storage medium. The thermal storage heat exchanger (30) and the auxiliary heat exchanger (40) are connected to the thermal storage circuit (20). Further, the retention portion (50) is provided in the thermal storage circuit (20). In this example, the thermal storage circuit (20) includes a thermal storage tank (21) and a circulation pump (22).

<<Thermal Storage Tank>>

The thermal storage tank (21) is a hollow container, and stores the thermal storage medium. The thermal storage tank (21) is provided with an outlet (201) and an inlet (202). The outlet (201) is located higher than the inlet (202). In this example, the thermal storage tank (21) is in a cylinder-like shape with its both ends closed, and is arranged such that the axial direction thereof is along a vertical direction.

<<Circulation Pump>>

The circulation pump (22) is provided to circulate the thermal storage medium in the thermal storage circuit (20). Specifically, the circulation pump (22) transfers the thermal storage medium, and is capable of changing a transfer amount (i.e., a discharge amount) of the thermal storage medium in response to the control by the controller (100).

<Thermal Storage Medium>

The thermal storage medium is a thermal storage material which turns into slurry when cooled (i.e., a thermal storage material with fluidity). Examples of the thermal storage medium include a tetra-n-butyl ammonium bromide (TBAB) aqueous solution, a trimethylolethane (TME) aqueous solution, paraffin slurry, etc. For example, if a tetra-n-butyl ammonium bromide aqueous solution is cooled and the temperature thereof becomes lower than a predetermined saturation temperature (i.e., a melting point), clathrate hydrates (i.e., crystals) comprised of tetra-n-butyl ammonium bromide and water molecules are formed and the tetra-n-butyl ammonium bromide aqueous solution turns into slurry with high viscosity. In contrast, when the tetra-n-butyl ammonium bromide aqueous solution in the form of slurry is heated and the temperature thereof becomes higher than the melting point, the clathrate hydrates are melted and the tetra-n-butyl ammonium bromide aqueous solution becomes a fluid with high fluidity. Here, the melting point of the tetra-n-butyl ammonium bromide aqueous solution (a temperature at which the clathrate hydrates are formed) is higher than 0° C. (e.g., about 10° C.).

<Thermal Storage Heat Exchanger>

The thermal storage heat exchanger (30) exchanges heat between the refrigerant in the refrigerant circuit (10) and the thermal storage medium in the thermal storage circuit (20). Specifically, the thermal storage heat exchanger (30) uses the refrigerant in the refrigerant circuit (10) as a heat sink when cold thermal energy (energy for cooling) is stored in the thermal storage medium in the thermal storage circuit (20). In this example, the thermal storage heat exchanger (30) has a first path (31) connected in series with the refrigerant circuit (10) as part of the refrigerant circuit (10) and a second path (32) connected in series with the thermal storage circuit (20) as part of the thermal storage circuit (20), and exchanges heat between the refrigerant flowing in the first path (31) and the thermal storage medium flowing in the second path (32). More specifically, the first path (31) of the thermal storage heat exchanger (30) is connected in series between the outdoor expansion valve (13) and the indoor expansion valve (14) (specifically, between the first intermediate portion and the second intermediate portion of the third refrigerant pipe (P13)) as part of the third refrigerant pipe (P13) of the refrigerant circuit (10). The second path (32) of the thermal storage heat exchanger (30) is connected in series between the outlet (201) and the inlet (202) of the thermal storage tank (21) in the thermal storage circuit (20). In this example, the thermal storage heat exchanger (30) is provided in the outdoor unit (3).

<Auxiliary Heat Exchanger>

The auxiliary heat exchanger (40) exchanges heat between the refrigerant in the refrigerant circuit (10) and the thermal storage medium in the thermal storage circuit (20). Specifically, the auxiliary heat exchanger (40) uses the refrigerant in the refrigerant circuit (10) as a heat source when cold thermal energy is stored in the thermal storage medium in the thermal storage circuit (20). In this example, the auxiliary heat exchanger (40) has a first path (41) connected in series with the refrigerant circuit (10) as part of the refrigerant circuit (10) and a second path (42) connected in series with the thermal storage circuit (20) as part of the thermal storage circuit (20), and exchanges heat with the refrigerant flowing in the first path (41) and the thermal storage medium flowing in the second path (42). More specifically, the first path (41) of the auxiliary heat exchanger (40) is connected in series between the outdoor heat exchanger (12) and the outdoor expansion valve (13) as part of the second refrigerant pipe (P12) of the refrigerant circuit (10). The second path (42) of the auxiliary heat exchanger (40) is connected in series between the outlet (201) of the thermal storage tank (21) and an inlet-side end of the second path (32) of the thermal storage heat exchanger (30) in the thermal storage circuit (20). In this example, the auxiliary heat exchanger (40) is provided in the outdoor unit (3).

<Retention Portion>

The retention portion (50) is provided in the thermal storage circuit (20) to retain crystals contained in the thermal storage medium. In this example, the retention portion (50) is provided between an outlet-side end of the second path (42) of the auxiliary heat exchanger (40) and the inlet-side end of the second path (32) of the thermal storage heat exchanger (30) in the thermal storage circuit (20). In this example, a thermal storage unit (2) includes the thermal storage tank (21), the circulation pump (22), and the retention portion (50).

<Pipe Connection in Thermal Storage Circuit>

In this example, the outlet (201) of the thermal storage tank (21) and an inlet-side end of the second path (42) of the auxiliary heat exchanger (40) are connected to each other by a first thermal storage medium pipe (P21); the outlet-side end of the second path (42) of the auxiliary heat exchanger (40) and the inlet-side end of the second path (32) of the thermal storage heat exchanger (30) are connected to each other by a second thermal storage medium pipe (P22); and an outlet-side end of the second path (32) of the thermal storage heat exchanger (30) and the inlet (202) of the thermal storage tank (21) are connected to each other by a third thermal storage medium pipe (P23). The circulation pump (22) and the retention portion (50) are disposed in the second thermal storage medium pipe (P22). Specifically, the circulation pump (22) is disposed between the second path (42) of the auxiliary heat exchanger (40) and the retention portion (50) in the second thermal storage medium pipe (P22).

<Example Configuration of Retention Portion>

In this example, the retention portion (50) includes a retention filter (60) as shown in FIG. 2. The retention filter (60) is provided inside the second thermal storage medium pipe (P22) (in this example, at an inside portion of the second thermal storage medium pipe (P22) between the circulation pump (22) and the second path (32) of the thermal storage heat exchanger (30)) to catch and retain crystals contained in the thermal storage medium. The white arrows in FIG. 2 indicate a flow direction of the thermal storage medium. That is, the crystals contained in the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) are caught when the thermal storage medium passes through the retention filter (60). Thereafter, the thermal storage medium flows in the second path (32) of the thermal storage heat exchanger (30). That is, the crystals contained in the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) can be caught and retained by the retention filter (60). Further, the crystals of the thermal storage medium which are retained by the retention filter (60) can be brought into contact with the high-temperature thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) (i.e., the thermal storage medium heated in the auxiliary heat exchanger (40) by the high-temperature, high-pressure refrigerant) and be melted.

In this example, the retention filter (60) includes a mesh member which can catch the crystals contained in the thermal storage medium, and allow the thermal storage medium (specifically, an aqueous solution) to pass therethrough. The retention filter (60) is in a cylinder-like shape of which the cross sectional area is gradually reduced from an upstream side to a downstream side in the flow direction of the thermal storage medium.

<Cool Storage Mode>

Next, a cool storage mode of the air conditioner (1) will be described with reference to FIG. 3. In the cool storage mode, the refrigerant circuit (10) performs an operation (a cool storage operation) in which the refrigerant is circulated such that the refrigerant condensed in the outdoor heat exchanger (12) is evaporated in the first path (31) of the thermal storage heat exchanger (30). In this example, the refrigerant circuit (10) performs a refrigeration cycle in which the outdoor heat exchanger (12) serves as a condenser and the thermal storage heat exchanger (30) serves as an evaporator. On the other hand, in the thermal storage circuit (20), the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet (201) of the thermal storage tank (21) sequentially passes through the second path (42) of the auxiliary heat exchanger (40), the retention portion (50), and the second path (32) of the thermal storage heat exchanger (30), and thereafter flows into the inlet (202) of the thermal storage tank (21).

In the refrigerant circuit (10), the four-way switching valve (16) is set to the first state; the first open/close valve (V1) and the third open/close valve (V3) are set to a closed state; and the second open/close valve (V2) is set to an open state. Further, the indoor expansion valve (14) is set to a fully-opened state, and the degree of opening of the outdoor expansion valve (13) is set to a predetermined degree of opening (a degree of opening which makes a degree of superheat of the refrigerant at the exit of the first path (31) of the thermal storage heat exchanger (30) a predetermined target value). Then, the compressor (11) and the indoor fan (17) are actuated.

The refrigerant discharged from the compressor (11) flows into the outdoor heat exchanger (12) via the first refrigerant pipe (P11), and dissipates heat to the outdoor air and condenses while passing through the outdoor heat exchanger (12). The refrigerant condensed in the outdoor heat exchanger (12) flows into the first path (41) of the auxiliary heat exchanger (40) via the second refrigerant pipe (P12), and heats the thermal storage medium flowing in the second path (42) of the auxiliary heat exchanger (40) while passing through the first path (41) of the auxiliary heat exchanger (40). The refrigerant having flowed out of the first path (41) of the auxiliary heat exchanger (40) flows into the outdoor expansion valve (13), and is decompressed when passing through the outdoor expansion valve (13). The refrigerant decompressed by the outdoor expansion valve (13) flows into the first path (31) of the thermal storage heat exchanger (30) via the third refrigerant pipe (P13), and absorbs heat and evaporates while passing through the first path (31) of the thermal storage heat exchanger (30). The refrigerant having evaporated in the first path (31) of the thermal storage heat exchanger (30) is sucked into the compressor (11) via the second bypass pipe (PB2) and the fifth refrigerant pipe (P15), and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermal storage circuit (20). The thermal storage medium stored in the thermal storage tank (21) flows into the second path (42) of the auxiliary heat exchanger (40) via the first thermal storage medium pipe (P21). The thermal storage medium having flowed into the second path (42) of the auxiliary heat exchanger (40) is heated by the refrigerant flowing in the first path (41) of the auxiliary heat exchanger (40), while passing through the second path (42) of the auxiliary heat exchanger (40). The thermal storage medium heated by the auxiliary heat exchanger (40) flows in the second thermal storage medium pipe (P22) and passes through the circulation pump (22) and the retention portion (50), and then flows into the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium having flowed into the second path (32) of the thermal storage heat exchanger (30) is cooled by the refrigerant flowing in the first path (31) of the thermal storage heat exchanger (30), while passing through the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium cooled in the thermal storage heat exchanger (30) flows into the thermal storage tank (21) via the third thermal storage medium pipe (P23). The cold thermal energy is stored in the thermal storage medium in this manner.

<Use Cooling Mode>

Now, a use cooling mode of the air conditioner (1) will be described with reference to FIG. 4 and FIG. 5. A use cooling mode is an operation for cooling a room by using the cold thermal energy stored in the thermal storage tank (21). In the use cooling mode, the refrigerant circuit (10) performs an operation (a use cooling operation) in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger (30) is evaporated in the indoor heat exchanger (15). On the other hand, in the thermal storage circuit (20), the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet (201) of the thermal storage tank (21) sequentially passes through the second path (42) of the auxiliary heat exchanger (40), the retention portion (50), and the second path (32) of the thermal storage heat exchanger (30), and thereafter flows into the inlet (202) of the thermal storage tank (21). In this example, the use cooling mode includes two types of modes, i.e., a first use cooling mode and a second use cooling mode.

<<First Use Cooling Mode>>

First, a first use cooling mode of the air conditioner (1) will be described with reference to FIG. 4. In the first use cooling mode, the cold thermal energy stored in the thermal storage tank (21) and the cold thermal energy obtained by the refrigeration cycle of the refrigerant circuit (10) are used to cool the room. The refrigerant circuit (10) performs a refrigeration cycle in which the outdoor heat exchanger (12) serves as a condenser; the auxiliary heat exchanger (40) and the thermal storage heat exchanger (30) serve as a subcooler (i.e., a radiator); and the indoor heat exchanger (15) serves as an evaporator. On the other hand, in the thermal storage circuit (20), the thermal storage medium is circulated such that the thermal storage medium having flowed out of the outlet (201) of the thermal storage tank (21) sequentially passes through the second path (42) of the auxiliary heat exchanger (40), the retention portion (50), and the second path (32) of the thermal storage heat exchanger (30), and flows in the inlet (202) of the thermal storage tank (21).

In the refrigerant circuit (10), the four-way switching valve (16) is set to the first state; the first open/close valve (V1) and the second open/close valve (V2) are set to a closed state; and the third open/close valve (V3) is set to an open state. Further, the outdoor expansion valve (13) is set to a fully-opened state, and a degree of opening of the indoor expansion valve (14) is set to a predetermined degree of opening (a degree of opening which makes a degree of superheat of the refrigerant at the exit of the indoor heat exchanger (15) a predetermined target value). Then, the compressor (11), the indoor fan (17), and the indoor fan (18) are actuated.

The refrigerant discharged from the compressor (11) flows into the outdoor heat exchanger (12) via the first refrigerant pipe (P11), and dissipates heat to the outdoor air and condenses while passing through the outdoor heat exchanger (12). The refrigerant condensed in the outdoor heat exchanger (12) flows into the first path (41) of the auxiliary heat exchanger (40) via the second refrigerant pipe (P12), and is cooled by the thermal storage medium flowing in the second path (42) of the auxiliary heat exchanger (40) while passing through the first path (41) of the auxiliary heat exchanger (40). The refrigerant having flowed out of the second path (42) of the auxiliary heat exchanger (40) flows into the first path (31) of the thermal storage heat exchanger (30) via the third refrigerant pipe (P13), and is cooled by the thermal storage medium flowing in the second path (32) of the thermal storage heat exchanger (30) while passing through the first path (31) of the thermal storage heat exchanger (30). The refrigerant having passed through the first path (31) of the thermal storage heat exchanger (30) flows into the indoor expansion valve (14) via the third refrigerant pipe (P13), and is decompressed when passing through the indoor expansion valve (14). The refrigerant decompressed by the indoor expansion valve (14) flows into the indoor heat exchanger (15) via the fourth refrigerant pipe (P14), and absorbs heat from the indoor air and evaporates while passing through the indoor heat exchanger (15). As a result, the indoor air is cooled. The refrigerant having evaporated in the indoor heat exchanger (15) is sucked into the compressor (11) via the fifth refrigerant pipe (P15), and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermal storage circuit (20). The thermal storage medium stored in the thermal storage tank (21) flows into the second path (42) of the auxiliary heat exchanger (40) via the first thermal storage medium pipe (P21), and absorbs heat from the refrigerant flowing in the first path (41) of the auxiliary heat exchanger (40) while passing through the second path (42) of the auxiliary heat exchanger (40). The thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) flows in the second thermal storage medium pipe (P22) and passes through the circulation pump (22) and the retention portion (50), and then flows into the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium having flowed into the second path (32) of the thermal storage heat exchanger (30) absorbs heat from the refrigerant passing through the first path (31) of the thermal storage heat exchanger (30) while passing through the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium having flowed out of the second path (32) of the thermal storage heat exchanger (30) flows into the thermal storage tank (21) via the third thermal storage medium pipe (P23). The cold thermal energy is given to the refrigerant from the thermal storage medium in this manner.

<<Second Use Cooling Mode>>

Now, a second use cooling mode of the air conditioner (1) will be described with reference to FIG. 5. In the second use cooling mode, only the cold thermal energy stored in the thermal storage tank (21) is used to cool the room. The refrigerant circuit (10) performs a refrigeration cycle in which the thermal storage heat exchanger (30) serves as a condenser and the indoor heat exchanger (15) serves as an evaporator. On the other hand, in the thermal storage circuit (20), the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet (201) of the thermal storage tank (21) sequentially passes through the second path (42) of the auxiliary heat exchanger (40), the retention portion (50), and the second path (32) of the thermal storage heat exchanger (30), and flows into the inlet (202) of the thermal storage tank (21).

In the refrigerant circuit (10), the four-way switching valve (16) is set to the first state; the second open/close valve (V2) is set to a closed state; and the first open/close valve (V1) and the third open/close valve (V3) are set to the open state. Further, the outdoor expansion valve (13) is set to a fully-opened state, and a degree of opening of the indoor expansion valve (14) is set to a predetermined degree of opening (a degree of opening which makes a degree of superheat of the refrigerant at the exit of the indoor heat exchanger (15) a predetermined target value). Then, the compressor (11) and the indoor fan (18) are actuated. In this example, the compressor (11) severs as a gas pump.

The refrigerant discharged from the compressor (11) flows into the first path (31) of the thermal storage heat exchanger (30) via the first refrigerant pipe (P11), the first bypass pipe (PB1), and the third refrigerant pipe (P13), and dissipates heat to the thermal storage medium flowing in the second path (32) of the thermal storage heat exchanger (30) and condenses while passing through the first path (31) of the thermal storage heat exchanger (30). The refrigerant having flowed out of the first path (31) of the thermal storage heat exchanger (30) flows into the indoor expansion valve (14) via the third refrigerant pipe (P13), and passes through the indoor expansion valve (14) and flows into the indoor heat exchanger (15). The refrigerant having flowed into the indoor heat exchanger (15) absorbs heat from the indoor air and evaporates while passing through the indoor heat exchanger (15). As a result, the indoor air is cooled. The refrigerant having evaporated in the indoor heat exchanger (15) is sucked into the compressor (11) via the fifth refrigerant pipe (P15), and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermal storage circuit (20). The thermal storage medium stored in the thermal storage tank (21) flows into the second path (42) of the auxiliary heat exchanger (40) via the first thermal storage medium pipe (P21). The thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) flows in the second thermal storage medium pipe (P22) and passes through the circulation pump (22) and the retention portion (50), and then flows into the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium having flowed into the second path (32) of the thermal storage heat exchanger (30) absorbs heat from the refrigerant passing through the first path (31) of the thermal storage heat exchanger (30) while passing through the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium having flowed out of the second path (32) of the thermal storage heat exchanger (30) flows into the thermal storage tank (21) via the third thermal storage medium pipe (P23). The cold thermal energy is given to the refrigerant from the thermal storage medium in this manner.

<Simple Cooling Mode>

Now, a simple cooling mode of the air conditioner (1) will be described with reference to FIG. 6. In the simple cooling mode, only the cold thermal energy which can be obtained by the refrigeration cycle of the refrigerant circuit (10) is used to cool the room. The refrigerant circuit (10) performs a refrigeration cycle in which the outdoor heat exchanger (12) serves as a condenser and the indoor heat exchanger (15) serves as an evaporator. On the other hand, the thermal storage medium is not circulated in the thermal storage circuit (20).

In the refrigerant circuit (10), the four-way switching valve (16) is set to the first state; the first open/close valve (V1) and the second open/close valve (V2) are set to the closed state; and the third open/close valve (V3) is set to the open state. Further, the outdoor expansion valve (13) is set to a fully-opened state, and a degree of opening of the indoor expansion valve (14) is set to a predetermined degree of opening (a degree of opening which makes a degree of superheat of the refrigerant at the exit of the indoor heat exchanger (15) a predetermined target value). Then, the compressor (11), the indoor fan (17), and the indoor fan (18) are actuated.

The refrigerant discharged from the compressor (11) flows into the outdoor heat exchanger (12) via the first refrigerant pipe (P11), and dissipates heat to the outdoor air and condenses while passing through the outdoor heat exchanger (12). The refrigerant condensed in the outdoor heat exchanger (12) flows into the indoor expansion valve (14) via the second refrigerant pipe (P12) and the third refrigerant pipe (P13), and is decompressed when passing through the indoor expansion valve (14). The refrigerant decompressed by the indoor expansion valve (14) flows into the indoor heat exchanger (15) via the fourth refrigerant pipe (P14), and absorbs heat from the indoor air and evaporates while passing through the indoor heat exchanger (15). As a result, the indoor air is cooled. The refrigerant having evaporated in the indoor heat exchanger (15) is sucked into the compressor (11) via the fifth refrigerant pipe (P15), and is compressed.

<Simple Heating Mode>

Now, a simple heating mode of the air conditioner (1) will be described with reference to FIG. 7. In the simple heating mode, hot thermal energy (energy for heating) which can be obtained by the refrigeration cycle of the refrigerant circuit (10) is used to heat the room. The refrigerant circuit (10) performs a refrigeration cycle in which the indoor heat exchanger (15) serves as a condenser and the outdoor heat exchanger (12) serves as an evaporator. On the other hand, the thermal storage medium is not circulated in the thermal storage circuit (20).

In the refrigerant circuit (10), the four-way switching valve (16) is set to the second state; the first open/close valve (V1) and the second open/close valve (V2) are set to the closed state; and the third open/close valve (V3) is set to the open state. Further, the indoor expansion valve (14) is set to a fully-opened state, and a degree of opening of the outdoor expansion valve (13) is set to a predetermined degree of opening (a degree of opening which makes a degree of superheat of the refrigerant at the exit of the outdoor heat exchanger (12) a predetermined target value). Then, the compressor (11), the indoor fan (17), and the indoor fan (18) are actuated.

The refrigerant discharged from the compressor (11) flows into the indoor heat exchanger (15) via the fifth refrigerant pipe (P15), and dissipates heat to the indoor air and condenses while passing through the indoor heat exchanger (15). As a result, the indoor air is heated. The refrigerant condensed in the indoor heat exchanger (15) flows into the outdoor expansion valve (13) via the fourth refrigerant pipe (P14) and the third refrigerant pipe (P13), and is decompressed when passing through the outdoor expansion valve (13).

The refrigerant decompressed by the outdoor expansion valve (13) flows into the outdoor heat exchanger (12) via the second refrigerant pipe (P12), and absorbs heat from the outdoor air and evaporates while passing through the heat exchanger (12). The refrigerant having evaporated in the outdoor heat exchanger (12) is sucked into the compressor (11) via the first refrigerant pipe (P11), and is compressed.

<Behavior of Thermal Storage Medium in Cool Storage Mode>

Now, the behavior of the thermal storage medium in the thermal storage circuit (20) during a thermal storage mode will be described with reference to FIG. 3 and FIG. 8. In FIG. 8, the vertical axis indicates a temperature of the thermal storage medium, and the horizontal axis indicates time. That is, the length of the horizontal axis in FIG. 8 corresponds to a flow time of the thermal storage medium (i.e., a necessary period of time from when the thermal storage medium flows in, to when the thermal storage medium flows out) in the respective elements of the thermal storage circuit (20) (e.g., the auxiliary heat exchanger (40), the circulation pump (22), and the retention portion (50)). In FIG. 8, for simplicity of explanation, temperature changes in between the elements of the thermal storage circuit (20) are not shown.

The solid line (L11) in FIG. 8 shows a temperature change of the thermal storage medium in the thermal storage circuit (20) of the present embodiment. In this example, a melting point temperature of the thermal storage medium is 11.6° C., and a temperature of the thermal storage medium stored in the thermal storage tank (21) is equal to the melting point temperature of the thermal storage medium, that is, 11.6° C. The temperatures shown below are all examples.

When the circulation pump (22) is actuated in the cool storage mode as illustrated in FIG. 3, the thermal storage medium stored in the thermal storage tank (21) flows into the second path (42) of the auxiliary heat exchanger (40) via the first thermal storage medium pipe (P21), and is heated by the refrigerant flowing in the first path (41) of the auxiliary heat exchanger (40) (i.e., the high-temperature, high-pressure refrigerant flowing out of the outdoor heat exchanger (12)), while passing through the second path (42) of the auxiliary heat exchanger (40). Thus, as indicated by solid line (L11) in FIG. 8, the temperature of the thermal storage medium is increased from a temperature equal to the melting point temperature (11.6° C.) to a temperature (12.9° C.) higher than the melting point temperature. The crystals contained in the thermal storage medium are melted by heating the thermal storage medium to a temperature higher than the melting point temperature of the thermal storage medium.

Next, the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) flows into the circulation pump (22) via the second thermal storage medium pipe (P22), and is heated by the heat generated by driving the circulation pump (22), while passing through the circulation pump (22). Thus, as indicated by solid line (L11) in FIG. 8, the temperature of the thermal storage medium is increased from the temperature (12.9° C.) higher than the melting point temperature to a temperature (13.0° C.) much higher than the melting point temperature.

Next, the thermal storage medium having flowed out of the circulation pump (22) flows into the retention portion (50) via the second thermal storage medium pipe (P22), and is retained. Here, the thermal storage medium heated in the auxiliary heat exchanger (40) and the circulation pump (22) continues to flow in the retention portion (50). Thus, as indicated by solid line (L11) in FIG. 8, the temperature of the thermal storage medium in the retention portion (50) is maintained at the temperature (that is 13.0° C. in this example) higher than the melting point temperature. Melting of the crystals contained in the thermal storage medium continues to proceed by continuously heating the thermal storage medium to maintain the temperature of the thermal storage medium at a temperature higher than the melting temperature of the thermal storage medium, as described above.

Next, the thermal storage medium having flowed out of the retention portion (50) flows into the second path (32) of the thermal storage heat exchanger (30) via the second thermal storage medium pipe (P22), and is cooled by the refrigerant flowing in the first path (31) of the thermal storage heat exchanger (30) (i.e., the refrigerant which absorbs heat and evaporates in the first path (31) of the thermal storage heat exchanger (30)), while passing through the second path (32) of the thermal storage heat exchanger (30). Thus, the temperature of the thermal storage medium is reduced from the temperature (13.0° C.) higher than the melting point temperature to a temperature (e.g., 9° C. that is not shown in FIG. 8) lower than the melting point temperature.

<Comparison between the Present Embodiment and Comparative Example>

Now, the air conditioner (1) of the present embodiment and comparative examples (the first comparative example and the second comparative example) of the air conditioner (1) will be compared and described with reference to FIG. 8. The upper broken line (L21) in FIG. 8 shows changes in temperature of the thermal storage medium in the thermal storage circuit (20) in the case where the retention portion (50) is not provided in the air conditioner (1) (the first comparative example), and the lower broken line (L22) in FIG. 8 shows changes in temperature of the thermal storage medium in the thermal storage circuit (20) in the case where the retention portion (50) is not provided in the air conditioner (1) and the auxiliary heat exchanger (40) has low heat exchange properties (the second comparative example).

In the case where the retention portion (50) is not provided in the air conditioner (1) (in the case of the first comparative example), the thermal storage medium having flowed out of the thermal storage tank (21) sequentially passes through the second path (42) of the auxiliary heat exchanger (40) and the circulation pump (22), and thereafter flows into the second path (32) of the thermal storage heat exchanger (30). In this case, as indicated by the upper broken line (L21) in FIG. 8, the flow time of the thermal storage medium in the second path (42) of the auxiliary heat exchanger (40) is extended to ensure crystal heating time (time of heating and melting of the crystals of the thermal storage medium) in the auxiliary heat exchanger (40). This means that the second path (42) of the auxiliary heat exchanger (40) has a long length, causing an increase in size of the auxiliary heat exchanger (40). Further, as indicated by the upper broken line (L21) in FIG. 8, the thermal storage medium is heated more than necessary in the second path (42) of the auxiliary heat exchanger (40), and therefore, the thermal energy is wasted in the auxiliary heat exchanger (40).

If the heat exchange properties of the auxiliary heat exchanger (40) are reduced to reduce the waste of the thermal energy in the auxiliary heat exchanger (40) in the air conditioner (1) where the retention portion (50) is not provided (i.e., in the case of the second comparative example), as indicated by the lower broken line (L22) in FIG. 8, it is possible to prevent unnecessary heating of the thermal storage medium in the second path (42) of the auxiliary heat exchanger (40). However, in this case, as well, the flow time of the thermal storage medium in the second path (42) of the auxiliary heat exchanger (40) needs to be extended to ensure crystal heating time (time of heating and melting of the crystals of the thermal storage medium) in the auxiliary heat exchanger (40). As a result, the auxiliary heat exchanger (40) is increased in size.

In contrast, in the air conditioner (1) of the present embodiment, it is possible to ensure crystal heating time (time of heating and melting of the crystals of the thermal storage medium) due to time in which the thermal storage medium is retained in the retention portion (50), as indicated by the solid line (L11) in FIG. 8. Therefore, the second path (42) of the auxiliary heat exchanger (40) does not need to be elongated. As a result, it is possible to reduce an increase in size of the auxiliary heat exchanger (40).

<Effects of the Embodiment>

As described above, due to the provision of the auxiliary heat exchanger (40), the thermal storage medium on the upstream side of the second path (32) of the thermal storage heat exchanger (30) (i.e., the thermal storage medium flowing into the second path (32) of the thermal storage heat exchanger (30)) can be heated by the high-temperature, high-pressure refrigerant that has been condensed in the air heat exchanger (12) of the refrigerant circuit (10). Therefore, the crystals contained in the thermal storage medium on the upstream side of the second path (32) of the thermal storage heat exchanger (30) can be melted.

Further, due to the provision of the retention portion (50), the crystals of the thermal storage medium remaining in the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) (i.e., the crystals which have not been melted in the auxiliary heat exchanger (40)) can be retained in the retention portion (50). Moreover, the crystals of the thermal storage medium which are retained in the retention portion (50) can be brought into contact with and be melted by the high-temperature thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) (i.e., the thermal storage medium heated by the high-temperature, high-pressure refrigerant in the auxiliary heat exchanger (40)).

Since the crystal heating time (i.e., the time of heating and melting of the crystals contained in the thermal storage medium) on the upstream side of the second path (32) of the thermal storage heat exchanger (30) can be extended, it is possible to reduce the crystals of the thermal storage medium flowing into the thermal storage heat exchanger (30).

Further, the provision of the circulation pump (22) in between the second path (42) of the auxiliary heat exchanger (40) and the retention portion (50) in the thermal storage circuit (20) allows the crystals of the thermal storage medium remaining in the thermal storage medium flowing out of the second path (42) of the auxiliary heat exchanger (40) to be melted by the heat generated by driving the circulation pump (22). Thus, the crystal heating time on the upstream side of the second path (32) of the thermal storage heat exchanger (30) can be further extended, and the crystals of the thermal storage medium flowing into the thermal storage heat exchanger (30) can be further reduced.

The concentration of slurry (the concentration of the crystals) of the thermal storage medium stored in the thermal storage tank (21) tends to be increased from an upper portion to a lower portion of the thermal storage tank (21). Thus, flowing out of the crystals of the thermal storage medium stored in the thermal storage tank (21) through the outlet (201) of the thermal storage tank (21) can be reduced by providing the outlet (201) of the thermal storage tank (21) at a location higher than the inlet (202). As a result, the crystals of the thermal storage medium which flow into the thermal storage heat exchanger (30) can be further reduced.

Further, since the crystals of the thermal storage medium which flow into the thermal storage heat exchanger (30) can be reduced, it is possible to delay crystallization of the thermal storage medium in the second path (32) of the thermal storage heat exchanger (30). It is therefore possible to extend the time from the start of the cool storage mode until the thermal storage medium flow less easily in the second path (32) of the thermal storage heat exchanger (30) due to the crystallization of the thermal storage medium (e.g., the time until the second path (32) of the thermal storage heat exchanger (30) is clogged).

Further, since the cold thermal energy stored in the thermal storage medium in the cool storage mode can be used in the use cooling mode, it is possible to reduce power consumption of the cooling operation of the air conditioner (1).

<Heating Temperature of Auxiliary Heat Exchanger in Cool Storage Mode>

It is preferable that parameters of the air conditioner (1) (e.g., the length of the second path (42) of the auxiliary heat exchanger (40), and the length of a heat-transfer pipe of the outdoor heat exchanger (12)) and operational conditions of the air conditioner (1) (e.g., the number of rotations of the compressor (11), and a degree of opening of the outdoor expansion valve (13)) are determined such that when the thermal storage medium flowing in the second path (42) of the auxiliary heat exchanger (40) is heated in the cool storage mode by the refrigerant flowing in the first path (41) of the auxiliary heat exchanger (40) (the high-temperature, high-pressure refrigerant which has been condensed in the outdoor heat exchanger (12)), the temperature of the thermal storage medium becomes a temperature higher than the melting point temperature of the thermal storage medium (e.g., a temperature higher than the melting point temperature by 1° C. or more). In the air conditioner having the above configurations, the crystals contained in the thermal storage medium on the upstream side of the thermal storage heat exchanger (30) can be reliably melted in the cool storage mode.

<First Variation of Retention Portion>

As shown in FIG. 9, the retention portion (50) may include a retention tank (70). The retention tank (70) is a hollow container, and retains the thermal storage medium. The retention tank (70) is provided with an inlet (701) and an outlet (702). In this example, the height (H2) of a portion where the outlet (702) is formed is different from the height (H1) of a portion where the inlet (701) is formed. Specifically, the height (H2) of the outlet (702) is higher than the height (H1) of the inlet (701). Alternatively, the height (H2) of the outlet (702) may be equal to the height (H1) of the inlet (701). In this example, the retention tank (70) is in a cylinder-like shape with its both ends closed, and is arranged such that the axial direction thereof is along a vertical direction. Further, the retention tank (70) is incorporated in the second thermal storage medium pipe (P22) of the thermal storage circuit (20). Specifically, the second thermal storage medium pipe (P22) includes an upstream pipe (P31) and a downstream pipe (P32). The inlet (701) of the retention tank (70) is connected to the outlet-side end of the second path (42) of the auxiliary heat exchanger (40) by the upstream pipe (P31). The outlet (702) of the retention tank (70) is connected to the inlet-side end of the second path (32) of the thermal storage heat exchanger (30) by the downstream pipe (P32).

In this example, the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) flows into the thermal storage tank (21) through the inlet (701) of the retention tank (70) and is retained, and thereafter flows out through the outlet (702) of the retention tank (70) and flows into the second path (32) of the thermal storage heat exchanger (30). Thus, the crystals remaining in the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) can be retained in the retention tank (70) together with the thermal storage medium. Moreover, the crystals of the thermal storage medium which are retained in the retention tank (70) can be brought into contact with and be melted by the high-temperature thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40).

<Effects of Retention Portion of First Variation>

In the compressor having the above configurations, as well, it is possible to extend the crystal heating time (time of heating and melting of the crystals contained in the thermal storage medium) on the upstream side of the second path (32) of the thermal storage heat exchanger (30). It is therefore possible to reduce the crystals of the thermal storage medium flowing into the thermal storage heat exchanger (30).

<Second Variation of Retention Portion>

As shown in FIG. 10, the retention portion (50) may include a retention pipe (80). A middle portion (81) of the retention pipe (80) has a larger cross-sectional area (A1) than a cross-sectional area (A2) of each of end portions (82, 83) of the retention pipe (80). In this example, the middle portion (81) of the retention pipe (80) is in a cylinder-like shape, and each of the end portions (82, 83) of the retention pipe (80) is tapered such that the cross-sectional area thereof is gradually reduced from the cross-sectional area (A1) to the cross-sectional area (A2) in a direction from a base to a tip. Further, the retention pipe (80) is incorporated in the second thermal storage medium pipe (P22) of the thermal storage circuit (20). Specifically, the second thermal storage medium pipe (P22) includes the upstream pipe (P31) and the downstream pipe (P32). The first end portion (82) of the retention pipe (80) is connected to the outlet-side end of the second path (42) of the auxiliary heat exchanger (40) by the upstream pipe (P31). The second end portion (83) of the retention pipe (80) is connected to the inlet-side end of the second path (32) of the thermal storage heat exchanger (30) by the downstream pipe (P32).

In this example, the flow speed of the thermal storage medium in the middle portion (81) of the retention pipe (80) can be reduced since the cross-sectional area (A1) of the middle portion (81) is larger than the cross-sectional area (A2) of each of the end portions (82, 83). Thus, the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) flows into the retention pipe (80) through the first end portion (82) and is retained in the middle portion (81), and thereafter flows out through the second end portion (83) and flows into the second path (32) of the thermal storage heat exchanger (30). The crystals of the thermal storage medium which remain in the thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) can be retained in the retention pipe (80) together with the thermal storage medium having flowed out of the second path (42). Further, the crystals of the thermal storage medium which are retained in the retention pipe (80) can be brought into contact with and be melted by the high-temperature thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40).

<Effects of Retention Portion of Second Variation>

In the compressor having the above configurations, as well, it is possible to extend the crystal heating time (time of heating and melting of the crystals contained in the thermal storage medium) on the upstream side of the second path (32) of the thermal storage heat exchanger (30). It is therefore possible to reduce the crystals of the thermal storage medium flowing into the thermal storage heat exchanger (30).

<Other Embodiments>

In the above embodiments, an example in which the retention portion (50) includes one of the retention filter (60), the retention tank (70), or the retention pipe (80) has been described, but the retention portion (50) may include a combination of at least two of the retention filter (60), the retention tank (70), and the retention pipe (80). For example, as shown in FIG. 11, the retention portion (50) may include the retention filter (60) and the retention pipe (80). In this example, the retention filter (60) is provided inside the retention pipe (80).

Further, an example has been described in which, during the second use cooling mode (FIG. 5), the refrigerant is circulated such that the refrigerant having passed through the first path (31) of the thermal storage heat exchanger (30) is evaporated in the outdoor heat exchanger (15). However, the refrigerant circuit (10) may perform an operation in which the refrigerant is circulated such that the refrigerant having passed through both of the first path (41) of the auxiliary heat exchanger (40) and the first path (31) of the thermal storage heat exchanger (30) is evaporated in the outdoor heat exchanger (15). In this case, as shown in FIG. 12, one end of the first bypass pipe (PB1) is connected to an intermediate portion of the first refrigerant pipe (P11), and the other end of the first bypass pipe (PB1) is connected to an intermediate portion of the second refrigerant pipe (P12) (an intermediate portion located between the outdoor heat exchanger (12) and the auxiliary heat exchanger (40)) in the refrigerant circuit (10). Further, a fourth open/close valve (V5) is provided between the intermediate portion (the portion where the one end of the first bypass pipe (PB1) is connected) of the first refrigerant pipe (P11) and the outdoor heat exchanger (12). The fourth open/close valve (V5) is capable of switching between an open state and a closed state in response to the control by the controller (100). The fourth open/close valve (V5) is set to the closed state in the second use cooling mode, and is set to the open state in the other operations (i.e., the cool storage mode, the first use cooling mode, the simple cooling mode, and the simple heating mode). The other configurations are similar to those of the air conditioner (1) shown in FIG. 1.

In the second use cooling mode of the air conditioner (1) shown in FIG. 12, the four-way switching valve (16) is set to the first state; the second open/close valve (V2) and the fourth open/close valve (V5) are set to the closed state; and the first open/close valve (V1) and the third open/close valve (V3) are set to the open state, in the refrigerant circuit (10). Further, the outdoor expansion valve (13) is set to a fully-opened state; the degree of opening of the indoor expansion valve (14) is set to a predetermined degree of opening (a degree of opening which makes a degree of superheat of the refrigerant at the exit of the indoor heat exchanger (15) a predetermined target value). Then, the compressor (11) and the indoor fan (18) are actuated. In this example, the compressor (11) severs as a gas pump.

In the second use cooling mode shown in FIG. 12, the refrigerant discharged from the compressor (11) flows into the first path (41) of the auxiliary heat exchanger (40) via the first refrigerant pipe (P11) and the first bypass pipe (PB1), and dissipates heat to the thermal storage medium flowing in the second path (42) of the auxiliary heat exchanger (40) and condenses, while passing through the first path (41) of the auxiliary heat exchanger (40). The refrigerant having flowed out of the first path (41) of the auxiliary heat exchanger (40) flows into the first path (31) of the thermal storage heat exchanger (30) via the third refrigerant pipe (P13), and dissipates heat to the thermal storage medium flowing in the second path (32) of the thermal storage heat exchanger (30) and condenses, while passing through the first path (31) of the thermal storage heat exchanger (30). The refrigerant having flowed out of the first path (31) of the thermal storage heat exchanger (30) flows into the indoor expansion valve (14) via the third refrigerant pipe (P13), and passes through the indoor expansion valve (14) and flows into the indoor heat exchanger (15). The refrigerant having flowed into the indoor heat exchanger (15) absorbs heat from the indoor air and evaporates while passing through the indoor heat exchanger (15). As a result, the indoor air is cooled. The refrigerant having evaporated in the indoor heat exchanger (15) is sucked into the compressor (11) via the fifth refrigerant pipe (P15) and is compressed.

On the other hand, the circulation pump (22) is actuated in the thermal storage circuit (20). The thermal storage medium stored in the thermal storage tank (21) flows into the second path (42) of the auxiliary heat exchanger (40) via the first thermal storage medium pipe (P21), and absorbs heat from the refrigerant passing through the first path (41) of the auxiliary heat exchanger (40), while passing through the second path (42) of the auxiliary heat exchanger (40). The thermal storage medium having flowed out of the second path (42) of the auxiliary heat exchanger (40) passes through the second thermal storage medium pipe (P22), the circulation pump (22), and the retention portion (50), and thereafter flows into the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium having flowed into the second path (32) of the thermal storage heat exchanger (30) absorbs heat from the refrigerant passing through the first path (31) of the thermal storage heat exchanger (30), while passing through the second path (32) of the thermal storage heat exchanger (30). The thermal storage medium having flowed out of the second path (32) of the thermal storage heat exchanger (30) flows into the thermal storage tank (21) via the third thermal storage medium pipe (P23). The cold thermal energy is given to the refrigerant from the thermal storage medium in this manner.

The above embodiments may be appropriately combined for application to the air conditioner.

The above embodiments are merely preferred examples in nature, and are not intended to limit the scope, applications, and use of the invention.

Claims

1. An air conditioner, comprising:

a refrigerant circuit having an air heat exchanger which exchanges heat between a refrigerant and air;

a thermal storage circuit having a thermal storage tank configured to store a thermal storage medium which turns into slurry when cooled, and a circulation pump provided to circulate the thermal storage medium;

a thermal storage heat exchanger which is connected to the refrigerant circuit and to the thermal storage circuit, and exchanges heat between the refrigerant flowing in the refrigerant circuit and the thermal storage medium flowing in the thermal storage circuit;

an auxiliary heat exchanger which is connected to the refrigerant circuit and to the thermal storage circuit, and exchanges heat between the refrigerant flowing in the refrigerant circuit and the thermal storage medium flowing in the thermal storage circuit; and

a retention portion provided in the thermal storage circuit to retain crystals contained in the thermal storage medium, wherein

the refrigerant circuit performs a cool storage operation in which the refrigerant is circulated such that the refrigerant which has been condensed in the air heat exchanger and passed through the auxiliary heat exchanger is evaporated in the thermal storage heat exchanger, and

in the thermal storage circuit during the cool storage operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from an outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into an inlet of the thermal storage tank.

2. The air conditioner of claim 1, wherein

the retention portion includes a retention filter which catches and retains the crystals contained in the thermal storage medium.

3. The air conditioner of claim 1, wherein

the retention portion includes a retention tank which is provided with an inlet and an outlet, and which retains the thermal storage medium flowing therein through the inlet and discharges the thermal storage medium retained therein through the outlet.

4. The air conditioner of claim 1, wherein

the retention portion includes a retention pipe of which a middle portion has a larger cross-sectional area than a cross-sectional area of each of its end portions.

5. The air conditioner of claim 1, wherein

the circulation pump is provided between the auxiliary heat exchanger and the retention portion in the thermal storage circuit.

6. The air conditioner of claim 1, wherein

the outlet of the thermal storage tank is provided at a location higher than the inlet of the thermal storage tank.

7. The air conditioner of claim 1, wherein

the air heat exchanger is an outdoor heat exchanger,

the refrigerant circuit includes the air heat exchanger and an indoor heat exchanger, and performs the cool storage operation and a use cooling operation in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger is evaporated in the indoor heat exchanger,

in the thermal storage circuit during any one of the cool storage operation or the use cooling operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into the inlet of the thermal storage tank.

8. The air conditioner of claim 2, wherein

the circulation pump is provided between the auxiliary heat exchanger and the retention portion in the thermal storage circuit.

9. The air conditioner of claim 2, wherein

the outlet of the thermal storage tank is provided at a location higher than the inlet of the thermal storage tank.

10. The air conditioner of claim 2, wherein

the air heat exchanger is an outdoor heat exchanger,

the refrigerant circuit includes the air heat exchanger and an indoor heat exchanger, and performs the cool storage operation and a use cooling operation in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger is evaporated in the indoor heat exchanger,

in the thermal storage circuit during any one of the cool storage operation or the use cooling operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into the inlet of the thermal storage tank.

11. The air conditioner of claim 3, wherein

the circulation pump is provided between the auxiliary heat exchanger and the retention portion in the thermal storage circuit.

12. The air conditioner of claim 3, wherein

the outlet of the thermal storage tank is provided at a location higher than the inlet of the thermal storage tank.

13. The air conditioner of claim 3, wherein

the air heat exchanger is an outdoor heat exchanger,

the refrigerant circuit includes the air heat exchanger and an indoor heat exchanger, and performs the cool storage operation and a use cooling operation in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger is evaporated in the indoor heat exchanger,

in the thermal storage circuit during any one of the cool storage operation or the use cooling operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into the inlet of the thermal storage tank.

14. The air conditioner of claim 4, wherein

the circulation pump is provided between the auxiliary heat exchanger and the retention portion in the thermal storage circuit.

15. The air conditioner of claim 4, wherein

the outlet of the thermal storage tank is provided at a location higher than the inlet of the thermal storage tank.

16. The air conditioner of claim 4, wherein

the air heat exchanger is an outdoor heat exchanger,

the refrigerant circuit includes the air heat exchanger and an indoor heat exchanger, and performs the cool storage operation and a use cooling operation in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger is evaporated in the indoor heat exchanger,

in the thermal storage circuit during any one of the cool storage operation or the use cooling operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into the inlet of the thermal storage tank.

17. The air conditioner of claim 5, wherein

the outlet of the thermal storage tank is provided at a location higher than the inlet of the thermal storage tank.

18. The air conditioner of claim 17, wherein

the air heat exchanger is an outdoor heat exchanger,

the refrigerant circuit includes the air heat exchanger and an indoor heat exchanger, and performs the cool storage operation and a use cooling operation in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger is evaporated in the indoor heat exchanger,

in the thermal storage circuit during any one of the cool storage operation or the use cooling operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into the inlet of the thermal storage tank.

19. The air conditioner of claim 5, wherein

the air heat exchanger is an outdoor heat exchanger,

the refrigerant circuit includes the air heat exchanger and an indoor heat exchanger, and performs the cool storage operation and a use cooling operation in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger is evaporated in the indoor heat exchanger,

in the thermal storage circuit during any one of the cool storage operation or the use cooling operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into the inlet of the thermal storage tank.

20. The air conditioner of claim 6, wherein

the air heat exchanger is an outdoor heat exchanger,

the refrigerant circuit includes the air heat exchanger and an indoor heat exchanger, and performs the cool storage operation and a use cooling operation in which the refrigerant is circulated such that the refrigerant having passed through the thermal storage heat exchanger is evaporated in the indoor heat exchanger,

in the thermal storage circuit during any one of the cool storage operation or the use cooling operation, the thermal storage medium is circulated such that the thermal storage medium having flowed out from the outlet of the thermal storage tank sequentially passes through the auxiliary heat exchanger, the retention portion, and the thermal storage heat exchanger and flows into the inlet of the thermal storage tank.