AIR-CONDITIONING SYSTEM

According to one embodiment, an air conditioning system includes a compressor, a condenser, an expansion valve, a switching valve, an evaporator, a pump, a radiator, and a heat storage unit. The switching valve performs switching so that a first heat medium flows through either a first flow path or a second flow path. The pump supplies a second heat medium to the heat source. The heat storage unit has a heat storage material. The heat storage unit has a first heat exchange region in which heat is exchanged between the first heat medium flowing through the first flow path and the heat storage material. The heat storage unit has a second heat exchange region which is provided upstream of the radiator and in which heat is exchanged between the second heat medium supplied to the heat source and the heat storage material.

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Description
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-210318, filed on Sep. 27, 2011; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an air-conditioning system.

BACKGROUND

To cool a heating element such as a fuel cell mounted on a vehicle, there exists a cooling system which utilizes, as a heat sink, a heat medium used for indoor cooling by an air conditioning system.

For example, there is proposed a cooling system which utilizes, as a heat sink, a heat medium used for indoor cooling to cool a heating element mounted on a vehicle via a heat exchanger, in which an evaporator for indoor cooling by an air conditioning system and the heat exchanger provided with a heat storage material are connected in parallel via a switching valve.

Here, in an air conditioning system, there may be a case where indoor heating is required in addition to indoor cooling. In this case, frosting of the evaporator for indoor heating in a cold district may cause decrease of heating efficiency, damage of the evaporator or the like.

However, in the above-mentioned air conditioning system, using the heat of a heating element such as a fuel cell to remove the attached frost has not been considered. Therefore it becomes necessary to use a heater or the like to remove the frost, which may increase power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an air conditioning system according to a first embodiment.

FIG. 2A is a schematic cross-sectional view illustrating the heat storage unit and FIG. 2B is a cross-sectional view taken along the line between the arrows A-A′ in FIG. 2A.

FIG. 3 is a schematic graph illustrating a temporal change in the amount of heat of the second heat medium recovered from the heat source 31 (amount of heat recovered) when the vehicle is running.

FIG. 4A is a schematic cross-sectional view illustrating the heat storage unit and FIG. 4B is a cross-sectional view taken along the line between the arrows B-B′ in FIG. 4A.

FIG. 5 is a flowchart illustrating an operation method of the cooling side circuit 10a.

FIG. 6 is a block diagram illustrating an air conditioning system according to a second embodiment.

FIG. 7 is a flowchart illustrating an operation method in the heating side circuit 10c.

FIG. 8 is a block diagram illustrating an air conditioning system according to a third embodiment.

FIG. 9A is a schematic cross-sectional view illustrating the heat storage unit and FIG. 9B is a cross-sectional view taken along the line between the arrows C-C′ in FIG. 9A.

FIG. 10 is a flowchart illustrating an operation method in the heating side circuit 10d.

DETAILED DESCRIPTION

In general, according to one embodiment, an air conditioning system includes a compressor, a condenser, an expansion valve, a switching valve, an evaporator, a pump, a radiator, and a heat storage unit. The compressor compresses a first heat medium taken therein. The compressor discharges the first heat medium. The condenser is provided on a discharge side of the compressor. The expansion valve is provided on the outflow side of the condenser. The switching valve which is provided on the outflow side of the expansion valve and which performs switching so that the first heat medium flows through either a first flow path or a second flow path. The evaporator is provided downstream of confluence position of the first flow path and the second flow path, on the intake side of the compressor. The pump supplies a second heat medium to the heat source. The radiator releases heat of the second heat medium supplied to the heat source. The heat storage unit has a heat storage material. The heat storage unit has a first heat exchange region in which heat is exchanged between the first heat medium flowing through the first flow path and the heat storage material. The heat storage unit has a second heat exchange region which is provided upstream of the radiator and in which heat is exchanged between the second heat medium supplied to the heat source and the heat storage material.

Embodiments of the invention will now be described with reference to the drawings. In the specification and the drawings of the application, components similar to those described in regard to a drawing thereinabove are marked with like reference numerals, and a detailed description is omitted as appropriate.

In the following, an air conditioning system installed in an Electric Vehicle (EV) or a fuel cell car (FCV) will be described as an example.

In addition, while there is a case where the state of a first heat medium is liquid, gas, or gas-liquid two-phase state, it may also be simply referred to as the first heat medium.

In addition, while there is a case where the state of a second heat medium is liquid or gas-liquid two-phase state, it may also be simply referred to as the second heat medium.

First Embodiment

FIG. 1 is a block diagram illustrating an air conditioning system according to a first embodiment.

As shown in FIG. 1, an air conditioning system 1 is provided with a heat pump circuit 10 and a heat recovery circuit 30.

The heat pump circuit 10 is provided with a cooling side circuit 10a and a heating side circuit 10b. The cooling side circuit 10a lowers the temperature of the air used for cooling inside the vehicle by absorbing heat from the air supplied into the vehicle.

The heating side circuit 10b raises the temperature of the air used for heating inside the vehicle by causing the air supplied into the vehicle to absorb heat.

First, the cooling side circuit 10a will be illustrated. The cooling side circuit 10a is provided with a compressor 11, a switching valve 14, a condenser 12, an expansion valve 15, an evaporator 17, and a piping 22.

The intake side of the compressor 11 has both the outflow side of the evaporator 17 and the outflow side of an evaporator 18 provided in the heating side circuit 10b connected thereto. The discharge side of the compressor 11 has the inflow side of the switching valve 14 connected thereto.

The compressor 11 compresses gas of the first heat medium supplied from the evaporator 17 and the evaporator 18. The compressor 11 can be configured to compress, for example, gas of the first heat medium taken in from the intake side to thereby generate high-temperature, high-pressure gas of the first heat medium, and discharge the generated high-temperature and high-pressure gas of the first heat medium from the discharge side.

The outflow side of the switching valve 14 has both the inflow side of the condenser 12 and the inflow side of a condenser 13 provided in the heating side circuit 10b connected thereto.

The switching valve 14 switches the supply of the gas of the high-temperature and high-pressure first heat medium discharged from the compressor 11, to either of the condenser 12 and the condenser 13. The switching valve 14 can be set as, for example, a three-way valve which is provided with an electromagnetic coil and which switches the flow path by supplying or terminating power to the electromagnetic coil or the like.

The outflow side of the condenser 12 has the inflow side of the expansion valve 15 connected thereto.

The condenser 12, having a blower fan (not shown), for example, can be configured to exchange heat between the air blown by the blower fan from outside the vehicle, and the high-temperature and high-pressure gas of the first heat medium discharged from the compressor 11. The high-temperature and high-pressure gas of the first heat medium discharged from the compressor 11 is condensed by having its heat absorbed by the air blown from outside the vehicle.

The outflow side of the expansion valve 15 has the inflow side of the evaporator 17 connected thereto.

The expansion valve 15 adiabatically expands the first heat medium condensed by the condenser 12 to thereby reduce its pressure, and gasifies a part of the first heat medium to thereby be turned into the first heat medium in a gas-liquid two-phase state.

The outflow side of the evaporator 17 has the intake side of the compressor 11 connected thereto.

The evaporator 17 is provided inside a ventilation duct 21 having provided therein a blower fan 21a for supplying air into the vehicle. The evaporator 17 exchanges heat between the air blown by the blower fan 21a and the first heat medium in a gas-liquid two-phase state which has flown in from the expansion valve 15. The first heat medium in a gas-liquid two-phase state turns into gas of the first heat medium by absorbing heat from the blown air and is supplied to the compressor 11. In addition, the air having its heat absorbed by the evaporator 17 is supplied into the vehicle to be used for cooling inside the vehicle.

The piping 22 connects the components provided in the cooling side circuit 10a and serves as a flow path of the first heat medium.

Next, the heating side circuit 10b will be described.

The heating side circuit 10b is provided with the compressor 11, the switching valve 14, the condenser 13, an expansion valve 16, a heat storage unit 19, the evaporator 18, and pipings 22a to 23c.

The condenser 13 is provided on the discharge side of the compressor 11. The outflow side of the condenser 13 has the inflow side of the expansion valve 16 connected thereto via the piping 23a.

The condenser 13 is provided inside the above-mentioned ventilation duct 21.

The condenser 13 may be configured to exchange heat between the air blown by the blower fan 21a and the high-temperature and high-pressure gas of the first heat medium discharged from the compressor 11 via the switching valve 14. The high-temperature and high-pressure gas of the first heat medium discharged from the compressor 11 is condensed by having its heat absorbed by the blown air. In addition, the air blown to the condenser 13 is heated by absorbing heat from the gas of the first heat medium, and the heated air is supplied into the vehicle to be used for heating inside the vehicle.

The expansion valve 16 is provided on the outflow side of the condenser 13. The outflow side of the expansion valve 16 has the inflow side of the evaporator 18 connected thereto via the piping 23c.

The expansion valve 16 adiabatically expands the first heat medium condensed by the condenser 13, to reduce its pressure, and gasifies a part of the first heat medium to thereby be turned into the first heat medium in a gas-liquid two-phase state.

The outflow side of the evaporator 18 has the intake side of the compressor 11 connected thereto via the piping 23b. The evaporator 18 is provided with, for example, a blower fan (not shown), and can be configured to exchange heat between the air blown by the blower fan from outside the vehicle and the first heat medium in a gas-liquid two-phase state which has flown in from the expansion valve 16 via the heat storage unit 19. The first heat medium in a gas-liquid two-phase state turns into gas of the first heat medium by absorbing heat from the blown air and is supplied to the compressor 11.

The heat storage unit 19 is provided between the expansion valve 16 and the evaporator 18.

A heat storage material 24 is provided inside the heat storage unit 19 and stores the heat supplied from the heat recovery circuit 30. In addition, the heat storage unit 19 supplies the heat stored in the heat storage material 24 to the first heat medium in a gas-liquid two-phase state, which is supplied to the evaporator 18 from the expansion valve 16. Supplying, to the evaporator 18, the first heat medium in a gas-liquid two-phase state which has been heated by supplying heat thereto can raise the temperature of the evaporator 18. Accordingly, frost can be prevented from sticking to the evaporator 18 in cold areas. In addition, even when there is frost sticking to the evaporator 18 at the time of start-up, the frost can be removed. As a result, decrease of heating efficiency, damage of the evaporator, or the like can be suppressed.

Details about the heat storage unit 19 will be described below.

In addition, the first heat medium used for the cooling side circuit 10a and the heating side circuit 10b can be, for example, ammonia, hydrofluorocarbon (HFC), hydrochlorofluoro carbon (HCFC), or the like.

Next, the heat recovery circuit 30 will be illustrated.

The heat recovery circuit 30 is provided with a pump 34, a radiator 33, and a piping 32.

The heat recovery circuit 30 cools a heat source 31 by absorbing heat of the heat source 31, and stores heat in the heat storage unit 19 by supplying the absorbed heat to the heat storage unit 19.

The intake side of pump 34 has the outflow side of the radiator 33 connected thereto. The heat source 31 is connected to the discharge side of the pump 34.

The pump 34 supplies the second heat medium to the heat source 31. In addition, the pump 34 circulates the second heat medium among the heat source 31, the heat storage unit 19, and the radiator 33.

The radiator 33 releases the heat of the second heat medium supplied to the heat source 31. The radiator 33 is provided with, for example, a blower fan (not shown), and can be configured to exchange heat between the air blown by the blower fan from outside the vehicle and the second heat medium which has flown in from the heat source 31 via the heat storage unit 19.

The radiator 33, for example, can be a radiator provided in an electric vehicle or a fuel-cell vehicle.

The second heat medium which has absorbed heat from the heat source 31 causes its heat to be absorbed by the heat storage unit 19, and further causes its heat to be absorbed by the air from outside the vehicle, blown by the radiator 33. Subsequently, the second heat medium which has been cooled by causing its heat to be absorbed is supplied to the heat source 31 and used for cooling the heat source 31.

The piping 32 connects the pump 34, the radiator 33, the heat storage unit 19, and the heat source 31, and serves as a flow path of the second heat medium.

The heat source 31 can be configured to generate heat for the motor, inverter, fuel-cell stack or the like provided in a electric vehicle or a fuel-cell vehicle, for example.

The second heat medium can be water, for example.

Next, the heat storage unit 19 will be further illustrated.

FIG. 2 is a schematic view illustrating the heat storage unit. Here, FIG. 2A is a schematic cross-sectional view illustrating the heat storage unit and FIG. 2B is a cross-sectional view taken along the line between the arrows A-A′ in FIG. 2A.

FIG. 3 is a schematic graph illustrating a temporal change in the amount of heat of the second heat medium recovered from the heat source 31 (amount of heat recovered) when the vehicle is running.

FIG. 3 illustrates a case of a vehicle running at the 10-15 driving mode.

In addition, the temperature at the intake port and the outlet port of the second heat medium in the heat source 31 was measured by an experiment, and thus the amount of heat recovered was tried to be calculated from the difference between the temperatures at the outlet port and the intake port of the second heat medium.

As can be seen from FIG. 3, the amount of heat generated in the heat source 31 varies with run time.

Here, the amount of heat exchange between the heat storage material 24 provided in the heat storage unit 19 and the first heat medium flowing inside the flow path 28 (heat absorption by the first heat medium from the heat storage material 24) becomes larger as the difference of temperature is larger between the heat storage material 24 and the first heat medium. In this case, as shown in FIG. 3, since the amount of heat generated from the heat source 31 varies depending on the running condition of the electric vehicle or fuel-cell vehicle, the temperature of the second heat medium flowing inside the flow path 29 also varies.

When, not via the heat storage material 24, direct heat exchange is performed between the first heat medium flowing inside the flow path 28 and the second heat medium flowing inside the flow path 29, it becomes difficult to supply heat to the first heat medium from the second heat medium when the amount of heat of the second heat medium is close to 0.

In contrast, when the temperature of the evaporator 18 (Tev2) is not less than a predetermined lower limit (Tmin), i.e, for example, it is not necessary to remove the frost sticking to the evaporator 18, the heat absorbed by the second heat medium from the heat source 31 during a period during which heat exchange is not necessary is wasted because it is released from the radiator 33 to the outside.

Therefore, in the embodiment, the heat storage unit 19 having the heat storage material 24 is provided so that the heat generated in the heat source 31 during a period during which heat exchange is not necessary can be stored.

Providing the heat storage unit 19 causes the temperature of the evaporator 18 (Tev2) to be less than a predetermined lower limit (Tmin), and thus heat can be supplied from the heat storage material 24 to the first heat medium when it is necessary to cause the first heat medium to absorb the heat.

In addition, as described below, a latent heat storage material (phase-change heat storage material) is used as the heat storage material 24, or a heat exchange region 26 (corresponding to an example of the first heat exchange region) in which the first heat medium and the heat storage material 24 exchange heat, and a heat exchange region 27 (corresponding to an example of the second heat exchange region) in which the second heat medium and the heat storage material 24 exchange heat are configured to be adjacent. Accordingly, since variation of the temperature of the second heat medium, if any, can be relaxed, the temperature of the heat storage material 24 can be maintained substantially constant. Therefore, the amount of heat exchanged at the time of heat exchange between the heat storage material 24 and the first heat medium can be maintained substantially constant, and thus it becomes possible to efficiently remove the frost sticking to the evaporator 18.

When the amount of heat stored in the heat storage material 24 is less than the amount of heat which is necessary to be supplied to the first heat medium, a heating unit 191 (for example, a heater or the like) which heats the heat storage material 24 can be provided. In this case, heat from heating unit 191 is absorbed by the heat storage material 24, and absorbed by the first heat medium in the heat exchange region 26.

Next, returning to FIG. 2, the heat storage unit 19 will be further described.

The heat storage unit 19 is provided with a casing 25, the flow path 28, the flow path 29, the heat storage material 24, and a nucleation unit 300.

Furthermore, the heat storage unit 19 has the heat exchange region 26 which exchanges heat between the first heat medium flowing through the flow path 28 and the heat storage material 24, and a heat exchange region 27 which is provided upstream of the radiator 33 and which exchanges heat between the second heat medium supplied to the heat source 31 and the heat storage material 24.

The heat exchange region 27 is provided closer to the center of the heat storage unit 19 than the heat exchange region 26.

The casing 25 has the flow path 28, the flow path 29, the heat storage material 24, and nucleation unit 300 housed therein.

The inner wall of the casing 25 has a concave portion 301 provided thereon. The concave portion 301 will be described below.

The flow path 28 is formed of a tubular member. The flow path 28 has an annulus part 28a and a joint 28b connected to the annulus part 28a. The annulus part 28a is provided on the heat exchange region 26 located on the inner wall side of the casing 25. The annulus part 28a is provided in the vicinity of one end of the casing 25. The piping 23c is connected to an end on the side opposite to the side connected to the annulus part 28a of the joint 28b. Accordingly, the first heat medium can flow inside the flow path 28. In addition, a plurality of the annulus part 28a can be provided.

The flow path 29 is formed of a tubular member. The flow path 29 has a spiral part 29a and joints 29b provided at both ends of the spiral part 29a.

The spiral part 29a is provided in the heat exchange region 27 provided inside the heat exchange region 26. The joint 29b has the piping 32 connected thereto. Accordingly, the second heat medium can flow inside the flow path 29.

In the heat storage unit 19 according to the embodiment, the flow path 29 through which the second heat medium having a high temperature flows is provided on the center side of the heat storage unit 19, and the flow path 28 through which the first heat medium having a temperature lower than the temperature of the second heat medium flows is provided on the inner wall side of the heat storage unit 19.

In this case, on the assumption that the flow path 29 through which the high-temperature second heat medium flows is provided on the inner wall side of the heat storage unit 19, heat dissipation becomes larger. In contrast to this, on the assumption that the flow path 29 through which the high-temperature second heat medium flows is provided on the center side of the heat storage unit 19, the distance to the surface of the casing 25 can be increased, and thus heat dissipation can be suppressed.

In addition, the ability (heat output) required when releasing heat to the first heat medium is generally higher than the ability required when storing the heat from the second heat medium. Therefore, it is preferred to increase the amount of heat exchanged between the heat storage material 24 and the first heat medium, by making the length of the flow path 28 through which the first heat medium flows longer. In this case, since the flow path 28 through which the first heat medium flows is provided on the inner wall side of the casing 25, it becomes easy to make the length of the flow path 28 longer.

Accordingly, assuming the above-mentioned arrangement of the flow path 28 and the flow path 29, the efficiency of heat exchange can be improved.

For the heat storage material 24, a material having a heat-storing density higher than the second heat medium can be used. The heat storage material 24 can be, for example, a latent heat storage material. As the latent heat storage material, an inorganic hydrate material (sodium acetate hydrate or sodium sulphate hydrate), an organic material (paraffin or erythritol), for example, can be exemplified. The heat storage material 24 liquefies when the temperature is higher than the melting point of the material to be formed, and solidifies when the temperature is lower than the melting point. In this case, a large amount of heat is absorbed or released at the melting point (phase-change temperature) at which phase-change occurs.

In addition, some latent heat storage materials may be capable of supercooling. A latent heat storage material capable of supercooling maintains a liquid state without solidification even when it the temperature is lower than the melting point. Furthermore, an external stimulation (for example, mechanical nucleation, electric nucleation, etc.) or addition of a crystalline nucleus can release supercooling and cause solidification to occur. In this case, heat can be released from the latent heat storage material by releasing supercooling and causing solidification to occur.

As a latent heat storage material capable of supercooling, sodium acetate trihydrate or the like can be exemplified. On the assumption that a latent heat storage material capable of supercooling is used, supercooling can be stably maintained also in a subfreezing environment. Moreover, on the assumption that a latent heat storage material capable of supercooling is used, heat can be stored for a long time. Therefore, even when heating is started from a state in which the latent heat storage material is left in a low temperature environment in winter for a long time, frost sticking to the evaporator 18 can be removed. In addition, on the assumption that a latent heat storage material capable of supercooling is used, it becomes possible to release heat at a desired time by external stimulation or the like. Accordingly, it becomes possible, for example, to remove the frost sticking to the evaporator 18 at a fixed time interval, or remove the frost sticking to the evaporator 18 when needed.

Inside the casing 25 having housed the flow path 28, the flow path 29, and the nucleation unit 300 is filled with the heat storage material 24. In this case, the flow path 28 is in contact with the heat storage material 24 located in the heat exchange region 26. The flow path 29 contacts the heat storage material 24 located in the heat exchange region 27. Therefore, the flow path 28 and the flow path 29 do not directly contact each other.

The second heat medium having absorbed heat by passing through the heat source 31 when the heat source 31 is generating heat, exchanges heat with the heat storage material 24 in the heat exchange region 27 of the heat storage unit 19, and the heat storage material 24 absorbs heat (stores heat). In this case, the amount of heat that can be absorbed from the second heat medium by the heat storage material 24 decreases when the melting point of the heat storage material 24 is high. In contrast, the amount of heat that can be absorbed from the heat storage material 24 by the first heat medium increases.

In this case, after having preliminarily determined, from the relation between the temperature of the second heat medium and the temperature of the first heat medium, the amount of heat to be absorbed by the heat storage material 24 from the second heat medium, a material of the heat storage material 24 having a melting point satisfying the amount of heat can be selected.

In addition, when heat exceeding the amount that can be stored in latent heat is supplied from the second heat medium to the heat storage material 24, the temperature of the heat storage material 24 rises higher than the melting point, and heat is stored by sensible heat.

In addition, when the temperature of the heat storage material 24 has risen higher than a predetermined value, the temperature of the heat storage material 24 can be prevented from becoming higher than the predetermined value by cooling the second heat medium by the radiator 33 provided in the heat recovery circuit 30.

The nucleation unit 300 is provided inside the heat storage unit 19 and causes the heat storage material 24 to nucleate. The nucleation unit 300 can be provided in a case where a latent heat storage material capable of supercooling is used as the heat storage material 24. As the nucleation unit 300, for example, an electrode which applies voltage to the heat storage material 24, or the like can be exemplified. When heat is desired to be absorbed from the heat storage material 24 into the first heat medium, i.e., for example, when the frost sticking to the evaporator 18 is removed, the nucleation unit 300 may apply a voltage to the heat storage material 24. When a voltage is applied to the heat storage material 24 by the nucleation unit 300, the heat storage material 24 is nucleated with the heat storage material 24 in the vicinity of the nucleation unit 300 being the starting point. Nucleation of the heat storage material 24 releases supercooling, and thus heat is released from the heat storage material 24.

Providing the nucleation unit 300 also makes it possible to release heat from the heat storage material 24 at a desired time. Accordingly, it becomes possible, for example, to remove the frost sticking to the evaporator 18 at a fixed time interval, or remove the frost sticking to the evaporator 18 when needed.

The inner wall of the casing 25 is provided with a concave portion 301, and the concave portion 301 is provided above the nucleation unit 300. For example, the nucleation unit 300 is provided downward in the gravity direction, inside the heat storage unit 19. In addition, the concave portion 301 is provided upward in the gravity direction, on the inner wall of the casing 25. When the heat storage material 24 is nucleated, the heat storage material 24 is subject to phase change from liquid to solid, and on this occasion, change of volume (density) occurs. In the embodiment, nucleation is caused from the lower side of the heat storage unit 19, by providing the nucleation unit 300 downward in the gravity direction. Then, the volume change having occurred by causing the heat storage unit 19 to nucleate from the lower side is absorbed by the concave portion 301 provided upward in the gravity direction of the heat storage unit 19.

FIG. 4 is a schematic view illustrating the heat storage unit according to another embodiment. Here, FIG. 4A is a schematic cross-sectional view illustrating the heat storage unit and FIG. 4B is a cross-sectional view taken along the line between the arrows B-B′ in FIG. 4A.

As shown in FIG. 4, the heat storage unit 19a is provided with the casing 25, a flow path 128, the flow path 29, the heat storage material 24, and the nucleation unit 300.

The flow path 128 is formed of a tubular member. The flow path 128 has a spiral part 128a and joints 128b provided at both ends of the spiral part 128a.

The spiral part 128a is provided in the heat exchange region 26. The joint 128b has the piping 32 connected thereto. Accordingly, the first heat medium can flow inside the flow path 128.

The heat storage unit 19a according to the embodiment can obtain a function and effect similar to the above-mentioned heat storage unit 19. In addition, the spiral part 128a being spiral-shaped can make circulation of the first heat medium smooth.

The form of the flow path provided in the heat storage unit is not limited to one which has been illustrated. For example, the flow path provided in the heat storage unit can be formed of a tubular member in a meandering manner.

Next, an operation method of the air conditioning system 1 will be illustrated.

(Cooling Operation)

FIG. 5 is a flowchart illustrating an operation method of the cooling side circuit 10a. When instructed to perform cooling inside the vehicle (step S01), the outflow side of the compressor 11 and the piping 22 are connected (step S02) by performing switching by the switching valve 14. Subsequently, by driving the compressor 11, the first heat medium is caused to circulate in the cooling side circuit 10a (step S03).

In this case, after having released heat to the outside of the vehicle in the condenser 12, the first heat medium which has been compressed in the compressor 11 is expanded in the expansion valve 15 and draws heat from the air in the evaporator 17. When the blower fan 21a operates, the air having heat drawn in the evaporator 17 is supplied into the vehicle. In this manner, cooling operation is performed.

(Heating Operation)

When instructed to perform heating, the outflow side of the compressor 11 and the piping 23a are connected by performing switching by the switching valve 14. Subsequently, by driving the compressor 11, the first heat medium is caused to circulate in the heating side circuit 10b.

In this case, the first heat medium which has been compressed in the compressor 11 is condensed in the condenser 13, and causes the air supplied by the blower fan 21a to absorb the condensation heat. Subsequently, the first heat medium is expanded in the expansion valve 16, circulates in the heating side circuit 10b by passing through the heat storage unit 19 and the evaporator 18, and returning to the compressor 11 again.

The heat storage unit 19 is filled with the heat storage material 24 having a melting point higher than the temperature of the inflowing first heat medium.

Since a large amount of heat is generated in the heat source 31, the heat can be recovered in the heat recovery circuit 30. Then, by causing the first heat medium to absorb the recovered heat via the heat storage unit 19, a part of the first heat medium can be vaporized. Accordingly, in the heat storage unit 19, by vaporizing a part of the first heat medium, evaporation in the evaporator 18 can be assisted. As a result, it becomes possible to reduce power consumption in the evaporator 18.

In addition, it is also possible to release heat from the heat storage material 24 by the above-mentioned nucleation unit 300 at a desired time. Accordingly, it is possible, for example, to remove the frost sticking to the evaporator 18 at a fixed time interval, or remove the frost sticking to the evaporator 18 when needed.

In contrast, in the heat recovery circuit 30, the heat generated by the heat source 31 is absorbed by the heat storage unit 19, and thus the amount of heat to be released by the radiator 33 is reduced. Therefore, it becomes possible to reduce power consumption for releasing heat in the radiator 33.

Since functions of respective components for cooling and heating operations are similar to that mentioned above, detailed description thereof is omitted.

Second Embodiment

FIG. 6 is a block diagram illustrating an air conditioning system according to a second embodiment.

As shown in FIG. 6, an air conditioning system 50 is provided with a heat pump circuit 51 and the heat recovery circuit 30.

The heat pump circuit 51 is provided with the cooling side circuit 10a and a heating side circuit 10c. The cooling side circuit 10a lowers the temperature of the air used for cooling inside the vehicle by absorbing heat from the air supplied into the vehicle.

The heating side circuit 10c raises the temperature of the air used for heating inside the vehicle by causing the air supplied into the vehicle to absorb heat.

The heating side circuit 10c is provided with the compressor 11, the switching valve 14, the condenser 13, the expansion valve 16, a switching valve 20, the heat storage unit 19, the evaporator 18, the pipings 23a, 23b, 23c (corresponding to an example of the first flow path), and 23d (corresponding to an example of the second flow path), and a temperature measuring unit 18a (corresponding to an example of the first temperature measuring unit).

One outflow side of the switching valve 20 has the inflow side of the heat storage unit 19 connected thereto via the piping 23c. The other outflow side of the switching valve 20 has the inflow side of the evaporator 18 connected thereto via the piping 23d. The inflow side of the switching valve 20 has the outflow side of the expansion valve 16 connected thereto via the piping 23a.

The switching valve 20 is provided on the outflow side of the expansion valve 16, and switches between the piping 23c and the piping 23d so that the first heat medium in a gas-liquid two-phase state which has flown out from the expansion valve 16 flows into any of the piping 23c and the piping 23d. The switching valve 20 can be, for example, a three-way valve which is provided with an electromagnetic coil and which switches the flow path by supplying or terminating power to the electromagnetic coil. However, the switching valve 20 is not limited to a three-way valve, and may be, for example, an on-off valve provided to both the piping 23c and the piping 23d.

The evaporator 18 is provided downstream of the confluence point of the piping 23c and the piping 23d, on the intake side of the compressor 11.

The temperature measuring unit 18a measures the temperature of the evaporator 18. The switching valve 20 performs switching, based on the temperature of the evaporator 18 measured by the temperature measuring unit 18a, so that the first heat medium flows through either the piping 23c or the piping 23d.

In the embodiment, the heat storage unit 19 can be selectively used by switching the flow of the first heat medium by the switching valve 20. Therefore, when the above-mentioned nucleation unit 300 is not provided, i.e., for example, even when latent heat storage material is not used as the heat storage material 24, it is possible to cause the first heat medium to absorb heat in the heat storage unit 19 at a desired time. Accordingly, it becomes possible, for example, to remove the frost sticking to the evaporator 18 at a fixed interval, or to remove the frost sticking to the evaporator 18 when needed.

Controlling the switching by the switching valve 20 based on the measurement result by the temperature measuring unit 18a will be described below.

Operation by the driver or the like also makes it possible to perform switching by the switching valve 20.

Next, an operation method of the air conditioning system 50 will be illustrated.

Since the cooling operation may be configured to be similar to the operation method in the cooling side circuit 10a illustrated in FIG. 5, description thereof is omitted.

(Heating Operation)

In the following, as an example, a case of controlling the switching by the switching valve 20 based on the measurement result by the temperature measuring unit 18a will be illustrated.

FIG. 7 is a flowchart illustrating an operation method in the heating side circuit 10c.

When instructed to perform heating inside the vehicle (step S11), the inflow side of the condenser 13 and the outflow side of the compressor 11 are connected by performing switching by the switching valve 14 (step S12).

Next, the temperature of the evaporator 18 (Tev2) is measured by the temperature measuring unit 18a (step S13). The measured temperature of the evaporator 18 can be converted into the temperature of the first heat medium flowing inside the evaporator 18. In this case, by preliminarily obtaining the relation between the temperature of the evaporator 18 and the temperature of the first heat medium flowing inside the evaporator 18 from an experiment or the like, temperature conversion can be performed based on the obtained relation.

When the measured temperature of the evaporator 18 is higher than a predetermined value, the switching valve 20 performs switching so that the first heat medium flows through the piping 23d.

For example, when the temperature of the evaporator 18 (Tev2) is not less than the predetermined lower limit (Tmin), inflow of the first heat medium into the heat storage unit 19 side is blocked by the switching valve 20 (steps S14 and S15a).

Subsequently, by driving the compressor 11, the first heat medium is caused to circulate through a predetermined path in the heating side circuit 10c (step S16). That is, the first heat medium is caused to circulate in the compressor 11, the switching valve 14, the condenser 13, the expansion valve 16, the switching valve 20, and the evaporator 18.

In this case, the air blown to the condenser 13 is heated by absorbing heat from the gas of the first heat medium, and the heated air is supplied into the vehicle to be used for heating inside the vehicle.

In addition, since the heat stored in the heat storage material 24 in the heat storage unit 19 is not absorbed by the first heat medium, the heat from the heat recovery circuit 30 can be stored in the heat storage material 24.

In contrast, when the measured temperature of the evaporator 18 is lower than the predetermined value, switching is performed so that the first heat medium flows through the piping 23c.

For example, when the temperature of the evaporator 18 (Tev2) is lower than the predetermined lower limit (Tmin), inflow of the first heat medium into the heat storage unit 19 side is carried out by the switching valve 20 (steps S14 and S15b).

Subsequently, by driving the compressor 11, the first heat medium is caused to circulate through a predetermined path in the heating side circuit 10c (step S16). That is, the first heat medium is caused to circulate in the compressor 11, the switching valve 14, the condenser 13, the expansion valve 16, the switching valve 20, the heat storage unit 19, and the evaporator 18.

Also in this case, the air blown to the condenser 13 is heated by absorbing heat from the gas of the first heat medium, and the heated air is supplied into the vehicle to be used for heating inside the vehicle.

Here, under a low-temperature and high-humidity environment such as in cold areas, freezing of moisture in the air may cause frost to stick to the evaporator 18. Since frost sticking to the evaporator 18 decreases the heat exchange efficiency (ability of vaporizing the first heat medium) in the evaporator 18, heating performance may significantly degrade.

Therefore, the embodiment is configured to determine whether or not frost is sticking by measuring the temperature of the evaporator 18 (Tev2) by the temperature measuring unit 18a provided in the evaporator 18.

For example, when the temperature of the evaporator 18 (Tev2) is lower than the predetermined lower limit (Tmin), it is determined that frost is sticking, and the first heat medium is caused to flow into the heat storage unit 19 side. As described above, the first heat medium which has flown into the flow path 28 of the heat storage unit 19 absorbs heat from the heat storage material 24. Therefore, load on the evaporator 18 is reduced, and thus the amount of sticking frost can be reduced. In addition, a heater may be provided in the evaporator 18.

Furthermore, a latent heat storage material capable of supercooling is used as the heat storage material 24, and when the latent heat storage material is in a supercooled state, supercooling is released by the nucleation unit 300 after it has been determined that the temperature of the evaporator 18 (Tev2) is lower than the predetermined lower limit (Tmin). Accordingly, even when the period from storing heat in the heat storage material 24 to releasing the heat is long, heat at the melting point can be released from the heat storage material 24, and thus the first heat medium can absorb sufficient heat.

Third Embodiment

FIG. 8 is a block diagram illustrating an air conditioning system according to a third embodiment.

As shown in FIG. 8, the air conditioning system 100 is provided with the heat pump circuit 101 and the heat recovery circuit 30.

The heat pump circuit 101 is provided with the cooling side circuit 10a and the heating side circuit 10d.

The cooling side circuit 10a lowers the temperature of the air used for cooling inside the vehicle drop by absorbing heat from the air supplied into the vehicle.

The heating side circuit 10d raises the temperature of the air used for heating inside the vehicle by causing the air supplied into the vehicle to absorb heat.

The heating side circuit 10d is provided with the compressor 11, the switching valve 14, the condenser 13, the expansion valve 16, the switching valve 20, the heat storage unit 190, the evaporator 18, the pipings 22a to 23d, the temperature measuring unit 18a, and a temperature measuring unit 11a (corresponding to an example of the second temperature measuring unit).

One outflow side of the switching valve 20 has the inflow side of the heat storage unit 190 connected thereto via the piping 23c. The other outflow side of the switching valve 20 had the inflow side of the evaporator 18 connected thereto via the piping 23d. The inflow side of the switching valve 20 has the outflow side of the expansion valve 16 connected thereto via the piping 23a.

The switching valve 20 switches the supply of the first heat medium in a gas-liquid two-phase state, flown out from the expansion valve 16, to either of the heat storage unit 190 and the evaporator 18.

The temperature measuring unit 11a measures the temperature of the compressor 11.

The switching valve 20 performs switching, based on the temperature of the compressor 11 measured by the temperature measuring unit 11a, so that the first heat medium flows through either the piping 23c or the piping 23d. In addition, the switching valve 20 performs switching, based on the temperature of the compressor 11 measured by the temperature measuring unit 11a and the temperature of the evaporator 18 measured by the temperature measuring unit 18a, so that the first heat medium flows through either the piping 23c or the piping 23d.

Also in the air conditioning system 100 according to the embodiment, the heat storage unit 190 can be selectively used by switching the flow of the first heat medium by the switching valve 20.

Controlling the switching by the switching valve 20 based on the measurement result by the temperature measuring unit 11a and the temperature measuring unit 18a will be described below.

Operation by the driver or the like also makes it possible to perform switching by the switching valve 20.

Next, the heat storage unit 190 will be further illustrated.

FIG. 9 is a schematic view illustrating the heat storage unit. FIG. 9A is a schematic cross-sectional view illustrating the heat storage unit and FIG. 9B is a cross-sectional view taken along the line between the arrows C-C′ in FIG. 9A.

As shown in FIG. 9, the heat storage unit 190 is provided with the casing 25, the flow path 128, a flow path 129, the heat storage material 24, the nucleation unit 300, and the temperature measuring unit 11a.

The flow path 129 is formed of a tubular member. The flow path 129 has a spiral part 129a and joints 129b provided at both ends of the spiral part 129a.

The spiral part 129a is provided in the heat exchange region 27 provided inside the heat exchange region 26. The joint 129b has the piping 32 connected thereto. Accordingly, the second heat medium can flow inside the flow path 129.

The compressor 11 is thermally connected to the heat storage unit 190.

With regard to that illustrated in FIG. 9, the compressor 11 is provided in a manner penetrating the center of the casing 25, and the heat storage material 24 and the casing 25 contact the outer face of the compressor 11. Then, the outer periphery side of the compressor 11 inside the casing 25 becomes the heat exchange region 27.

Since the compressor 11 generates heat when the compressor 11 is operated, the compressor 11 also serves as the heat source. Therefore, in the heat storage unit 190, heat generated from the compressor 11 can also be stored in the heat storage material 24.

In this case, when the temperature of the heat storage material 24 is lower than the temperature of the compressor 11, heat from the compressor 11 is absorbed (stored), via the casing 25 or directly, in the heat storage material 24. In contrast, when the temperature of the heat storage material 24 is higher than the temperature of the compressor 11, heat from the heat storage material 24 will be absorbed by the compressor 11.

Next, an operation method of the air conditioning system 100 will be illustrated.

Since the cooling operation can be configured to be similar to the operation method in the cooling side circuit 10a illustrated in FIG. 5, description thereof is omitted.

(Heating Operation)

In the following, as an example, a case of controlling the switching by the switching valve 20 based on the measurement result by the temperature measuring unit 11a and the temperature measuring unit 18a will be illustrated.

FIG. 10 is a flowchart illustrating an operation method in the heating side circuit 10d.

When instructed to perform heating inside the vehicle (step S31), the inflow side of the condenser 13 and the outflow side of the compressor 11 are connected by performing switching by the switching valve 14 (step S32).

Next, the temperature of the compressor 11 (Tcomp) is measured by the temperature measuring unit 11a (step S33).

When the measured temperature of the compressor 11 is lower than a predetermined value, the switching valve 20 performs switching so that the first heat medium flows through the piping 23d.

For example, when the temperature of the compressor 11 (Tcomp) is lower than a predetermined lower limit (Tcomp—min), inflow of the first heat medium into the heat storage unit 190 side is blocked by the switching valve 20 (steps S34 and S37).

In this case, by driving the compressor 11 (step S39), the first heat medium is caused to circulate through a predetermined path in the heating side circuit 10d. That is, the first heat medium is caused to circulate in the compressor 11, the switching valve 14, the condenser 13, the expansion valve 16, the switching valve 20, and the evaporator 18.

In this case, the air blown to the condenser 13 is heated by absorbing heat from the gas of the first heat medium, and the heated air is supplied into the vehicle to be used for heating inside the vehicle.

In addition, since the heat stored in the heat storage material 24 in the heat storage unit 190 is not absorbed by the first heat medium, the heat from the heat recovery circuit 30 can be stored in the heat storage material 24.

In addition, a latent heat storage material capable of supercooling is used as the heat storage material 24 and, when the latent heat storage material is in a supercooled state, supercooling is released by the nucleation unit 300 after it has been determined that the temperature of the compressor 11 (Tcomp) is lower than the predetermined lower limit (Tcomp—min). Accordingly, the heat stored in the heat storage material 24 can be absorbed by the compressor 11.

When the temperature of the compressor 11 is low, there is a risk in which the heat may escape from the gas of the compressed, high-temperature first heat medium to the compressor 11, resulting in a reduced heating performance.

Therefore, for example, when it is determined that the temperature of the compressor 11 (Tcomp) is lower than the predetermined lower limit (Tcomp—min), heat is provided from the heat storage tank 190 to the compressor 11, and thus escape of heat from the compressor 11 is suppressed.

In contrast, for example, when the temperature of the compressor (Tcomp) is not less than the predetermined lower limit (Tcomp—min), the temperature of the evaporator 18 (Tev2) is measured by the temperature measuring unit 18a (steps S34 and S35).

When, for example, the temperature of the evaporator 18 (Tev2) is not less than the predetermined lower limit (Tmin), inflow of the first heat medium into the heat storage unit 190 side is blocked by the switching valve 20 (steps S36 and S37).

In this case, by driving the compressor 11 (step S39), the first heat medium is caused to circulate through a predetermined path in the heating side circuit 10d. That is, the first heat medium is caused to circulate in the compressor 11, the switching valve 14, the condenser 13, the expansion valve 16, the switching valve 20, and the evaporator 18.

For example, when the temperature of the compressor 11 (Tcomp) is not less than the predetermined lower limit (Tcomp—min) and the temperature of the evaporator 18 (Tev2) is not less than the predetermined lower limit (Tmin), heat from the compressor 11 and heat from the heat recovery circuit 30 are stored in the heat storage material 24. In this case, since inflow of the first heat medium into the heat storage unit 190 side is blocked by the switching valve 20, the heat stored in the heat storage material 24 is not absorbed by the first heat medium.

In contrast to this, for example, when the temperature of the evaporator 18 (Tev2) is lower than the predetermined lower limit (Tmin), inflow of the first heat medium into the heat storage unit 190 side is caused by the switching valve 20 (steps S36 and S38).

In this case, by driving the compressor 11 (step S39), the first heat medium is caused to circulate through a predetermined path in the heating side circuit 10d. That is, the first heat medium is caused to circulate in the compressor 11, the switching valve 14, the condenser 13, the expansion valve 16, the switching valve 20, the heat storage unit 190, and the evaporator 18.

For example, when the temperature of the compressor 11 (Tcomp) is not less than the predetermined lower limit (Tcomp—min) and the temperature of the evaporator 18 (Tev2) is lower than the predetermined lower limit (Tmin), inflow of the first heat medium into the heat storage unit 190 side is caused by the switching valve 20. The first heat medium having flown into the flow path 128 of the heat storage unit 190 absorbs the heat from the heat storage material 24. Accordingly, load on the evaporator 18 is reduced, and thus the amount of sticking frost can be reduced. A heater may be provided in the evaporator 18.

In addition, a latent heat storage material capable of supercooling is used as the heat storage material 24 and, when the latent heat storage material is in a supercooled state, supercooling is released by the nucleation unit 300 after it has been determined that the temperature of the compressor 11 (Tcomp) is not less than the predetermined lower limit (Tcomp—min) and the temperature of the evaporator 18 (Tev2) is lower than the predetermined lower limit (Tmin). Accordingly, even when the period from storing heat in the heat storage material 24 to releasing the heat is long, heat at the melting point can be released from the heat storage material 24, and thus the first heat medium can absorb sufficient heat.

In the embodiment, when the temperature of the compressor 11 and the temperature of the second heat medium are higher than the temperature of the heat storage material 24, the heat storage material 24 absorbs heat from the compressor 11 and the second heat medium.

In contrast to this, when the temperature of the compressor 11 or the temperature of the first heat medium is low, the compressor 11 or the first heat medium absorbs heat from the heat storage material 24.

Therefore, in an electric vehicle or a fuel-cell vehicle, since heat can be used more efficiently inside the vehicle, power consumption when operating the air conditioning system can be further suppressed.

According to the embodiment illustrated above, an air conditioning system capable of reducing power consumption can be realized.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention. Moreover, above-mentioned embodiments can be combined mutually and can be carried out.

Claims

1. An air conditioning system comprising:

a compressor which compresses and discharges a first heat medium taken therein;
a condenser provided on a discharge side of the compressor;
an expansion valve provided on the outflow side of the condenser;
a switching valve which is provided on the outflow side of the expansion valve and which performs switching so that the first heat medium flows through either a first flow path or a second flow path;
an evaporator provided downstream of confluence position of the first flow path and the second flow path, on the intake side of the compressor;
a pump which supplies a second heat medium to the heat source;
a radiator which releases heat of the second heat medium supplied to the heat source; and
a heat storage unit having a heat storage material, wherein
the heat storage unit has a first heat exchange region in which heat is exchanged between the first heat medium flowing through the first flow path and the heat storage material, and a second heat exchange region which is provided upstream of the radiator and in which heat is exchanged between the second heat medium supplied to the heat source and the heat storage material.

2. The system according to claim 1, wherein the first flow path connects one outflow side of the switching valve and the evaporator via the heat storage unit, and the second flow path connects the other outflow side of the switching valve and the evaporator.

3. The system according to claim 1, wherein the second heat exchange region is provided closer to a center of the heat storage unit than the first heat exchange region.

4. The system according to claim 1, wherein the heat storage unit has a cylindrical shape, the first heat exchange region is provided on a side of an inner wall of the cylindrical heat storage unit, and the second heat exchange region is provided on a side of a center of the cylindrical heat storage unit.

5. The system according to claim 1 further comprising a first temperature measuring unit which measures temperature of the evaporator, wherein the switching valve performs switching, based on the measured temperature of the evaporator, so that the first heat medium flows through either the first flow path or the second flow path.

6. The system according to claim 1, wherein

the switching valve performs switching so that the first heat medium flows through the second flow path when the measured temperature of the evaporator is higher than a predetermined value, and
the switching valve performs switching so that the first heat medium flows through the first flow path when the measured temperature of the evaporator is lower than a predetermined value.

7. The system according to claim 1, wherein the compressor is thermally connected to the heat storage unit.

8. The system according to claim 7, further comprising a second temperature measuring unit which measures temperature of the compressor, wherein the switching valve performs switching, based on the measured temperature of the compressor, so that the first heat medium flows through either the first flow path or the second flow path.

9. The system according to claim 8, wherein the switching valve performs switching so that the first heat medium flows through the second flow path when the measured temperature of the compressor is lower than a predetermined value.

10. The system according to claim 1, further comprising a nucleation unit which is provided inside the heat storage unit and causes the heat storage material to nucleate.

11. The system according to claim 1, wherein the heat storage material is a latent heat storage material.

12. The system according to claim 11, wherein the latent heat storage material includes at least one type selected from the group consisting of sodium acetate hydrate, sodium sulphate hydrate, paraffin, erythritol, and sodium acetate trihydrate.

13. The system according to claim 9, further comprising a first temperature measuring unit which measures temperature of the evaporator, wherein

the heat storage material is a latent heat storage material capable of supercooling, and
when the heat storage material is in a supercooled state, and the measured temperature of the evaporator is lower than a predetermined value,
the nucleation unit releases the supercooled state of the heat storage material.

14. The system according to claim 9, wherein the nucleation unit is an electrode which applies a voltage to the heat storage material.

15. The system according to claim 9, wherein the nucleation unit causes the heat storage material to nucleate at a fixed time interval.

16. The system according to claim 10, wherein

the nucleation unit is provided downward in the gravity direction inside the casing.

17. The system according to claim 1, further comprising a heating unit which heats the heat storage material.

18. An air conditioning system comprising:

a compressor which compresses and discharges a first heat medium taken therein;
a condenser provided on a discharge side of a discharge side of the compressor;
an expansion valve provided on the outflow side of the condenser;
an evaporator provided on the outflow side of the expansion valve, and also on the intake side of the compressor;
a pump which supplies a second heat medium to the heat source;
a radiator which releases heat of the second heat medium supplied to the heat source; and
a heat storage unit having a heat storage material, wherein
the heat storage unit has a first heat exchange region which is provided upstream of the evaporator and in which heat is exchanged between the first heat medium and the heat storage material, and a second heat exchange region which is provided upstream of the radiator and in which heat is exchanged between the second heat medium supplied to the heat source and the heat storage material.

19. The system according to claim 18, wherein the second heat exchange region is provided closer to the center of the heat storage unit than the first heat exchange region.

20. The system according to claim 18, wherein the heat second exchange region is provided adjacent to the first heat exchange region.

Patent History
Publication number: 20130074533
Type: Application
Filed: May 2, 2012
Publication Date: Mar 28, 2013
Inventors: Ryosuke YAGI (Kanagawa-ken), Mitsunobu Yoshida (Kanagawa-ken), Katsumi Hisano (Chiba-ken), Takuya Hongo (Kanagawa-ken), Kei Matsuoka (Kanagawa-ken)
Application Number: 13/462,281
Classifications
Current U.S. Class: Condition Sensing (62/129); With Flow Control Or Compressor Details (62/324.6); Compressor-condenser-evaporator Circuit (62/498)
International Classification: F25B 1/00 (20060101); F25B 49/02 (20060101); F25B 13/00 (20060101);