JP2015210028A - Heat storage system and air conditioning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely make a heat storage medium as hydrate slurry from an overcooling state in a heat storage tank, in a heat storage system which uses the heat storage medium in which a clathrate hydrate is created by cooling.SOLUTION: A refrigerant in a refrigerant circuit and a heat storage medium in a heat storage circuit are heat-exchanged by a heat storage heat exchanger, the heat storage medium is cooled, and the heat storage medium is brought into an overcooled state at a temperature lower than a hydrate creation temperature. After that, the heat storage medium is heated by the refrigerant in the heat storage heat exchanger, and raised in temperature to a prescribed temperature not lower than the hydrate creation temperature. By this constitution, a temperature impact arises in the heat storage tank by the flow-in of the high-temperature heat storage medium, the low-temperature heat storage medium and the high-temperature heat storage medium are mixed with each other, disturbance abruptly occurs, and the inside of the heat storage tank is agitated. As a result, hydrate slurry originally existing in the heat storage tank is largely grown up. The hydrate slurry becomes a core for eliminating the overcooling state of the heat storage medium which flows into the heat storage tank succeedingly.

Description

  The present invention relates to a heat storage system that stores cold using the heat storage action of a heat storage medium, and an air conditioning system that performs air conditioning using the cold stored in the heat storage system.

  As shown in Patent Document 1, the heat storage system includes a heat storage circuit and a refrigerant circuit, and stores heat using a heat storage medium. There is also known an air conditioning system that performs indoor air conditioning using cold energy stored in a heat storage medium of the heat storage system. The heat storage circuit mainly includes a heat storage tank that stores a heat storage medium, a heat storage heat exchanger that exchanges heat between the heat storage medium and a heat medium such as a refrigerant, and a circulation pump. The refrigerant circuit is mainly configured by the heat storage heat exchanger and a use-side heat exchanger that cools indoor air using cold heat extracted from the heat storage medium by the heat storage heat exchanger.

  In Patent Document 1, a wettable powder that produces clathrate hydrate by cooling is used as a heat storage material (for example, tetra-n-butylammonium bromide), and an aqueous solution of this heat storage material is used as a heat storage medium. In patent document 1, the cool storage operation which stores cold heat in a heat storage tank is performed by cooling a heat storage medium with the heat exchanger for heat storage, and storing in a heat storage tank.

JP2013-083439A

  In a heat storage medium used in the above heat storage system, for example, a heat storage medium such as a tetra-n-butylammonium bromide (TBAB) aqueous solution, clathrate hydrate is generated when cooled stably to a temperature lower than the hydrate generation temperature. Therefore, it becomes a supercooled solution maintaining the solution state. This supercooled solution, that is, the supercooled heat storage medium, has characteristics that it is difficult to eliminate the supercooled state, that is, not to become a hydrate slurry, compared to ice as a heat storage medium. In addition, even when a small amount of hydrate slurry is present in the supercooled solution, even if the supercooled solution comes into contact with the hydrate slurry, the supercooled solution has characteristics that make it difficult to eliminate the supercooled state. ing. Therefore, in a heat storage system using such a heat storage medium, a method of canceling the supercooled state by bringing the water supercooled solution into contact with the seed ice produced by the seed ice generator as in the conventional dynamic ice heat storage system. However, even if it is adopted, a device such as a seed ice producing device capable of producing large seed ice is required, and there is a disadvantage that the cost is increased.

  Furthermore, a heat storage medium such as an aqueous solution of tetra n-butylammonium bromide (TBAB) has a high degree of supercooling when the pull-down operation is started from an initial state where no hydrate slurry is present in the heat storage tank (for example, 5 ° (C or higher), it is difficult to eliminate the supercooled state. If the supercooling degree is further increased, the supercooling state is eliminated by a small impact (for example, pressure fluctuation in a pipe through which the heat storage medium flows), and the heat storage medium becomes a hydrate slurry. If it is further increased, there is a drawback that the heat exchange rate in the heat storage heat exchanger is deteriorated.

  Furthermore, when the supercooled solution has canceled the supercooled state in the middle of the piping, the hydrate slurry grows and freezes at the portion where the supercooled solution is formed, and the piping is blocked. Even if the supercooled solution is heated with a heat storage heat exchanger to eliminate this blockage, heat transfer from the heat storage heat exchanger to the plugged portion of the pipe starts to freeze the hydrate slurry. It takes a long time for the clathrate hydrate to flow off the inner wall of the pipe. As a result, there arises a drawback that the heat storage amount of the heat storage tank cannot be secured in a desired time.

  This invention is made | formed in view of this point, The objective is to eliminate a supercooling state in a thermal storage tank in the thermal storage system using thermal storage media, such as tetra n butyl ammonium bromide (TBAB) aqueous solution. The purpose is to generate a large hydrate slurry as a core, and to reliably and reliably eliminate the supercooled state of the heat storage medium.

  The heat storage system of 1st invention has the heat storage tank (52) which stores the heat storage medium in which clathrate hydrate is produced | generated by cooling, the heat storage circuit (61) which circulates the said heat storage medium, and a refrigerant | coolant A refrigerant circuit (11) that circulates the refrigerant, and the heat storage circuit (61) and the refrigerant circuit (11) in common, and the refrigerant of the refrigerant circuit (11) and the heat storage medium of the heat storage circuit (61) A heat storage system (29) for exchanging heat between the heat storage tanks (52), comprising an operation control unit (100) for controlling the operation of storing heat in the heat storage tank (52), and the operation control unit ( 100) is a sensible heat storage operation for cooling the heat storage medium by the heat storage heat exchanger (29) so that the heat storage medium of the heat storage circuit (61) is set to a first predetermined temperature lower than the hydrate generation temperature. After the heat treatment, the heat storage medium of the heat storage circuit (61) is set to the hydrate formation temperature or higher. And performing heating operation for heating the heat storage medium in the heat storage heat exchanger (29).

  In this heat storage system, first, a sensible heat storage operation is performed, and the heat storage medium enters a supercooled state at a first predetermined temperature whose temperature is lower than the hydrate generation temperature. In this supercooled state, there is a little hydrate slurry in the heat storage tank.

  Thereafter, a heating operation is performed, and the temperature of the heat storage medium rises above the hydrate formation temperature. As a result, the heat storage medium whose temperature has increased in the heat storage heat exchanger flows into the heat storage tank, and the heat storage medium having a temperature lower than the hydrate generation temperature and the heat storage medium having a temperature higher than the hydrate generation temperature are mixed at once in the heat storage tank. As a result, a turbulent flow suddenly occurs and the heat storage tank is agitated. In this way, the heat control (temperature shock) of the heat storage medium causes mixing, turbulence, and agitation of heat storage media having different temperatures in the heat storage tank, so that many hydrate slurries originally existed. The supercooled heat storage medium comes into contact with each other, and the hydrate slurry that originally existed is surely greatly grown. And this grown hydrate slurry becomes the nucleus which cancels the supercooled state of the thermal storage medium which flows in in a thermal storage tank after that.

  The second invention is characterized in that, in the heat storage system, the first predetermined temperature is a temperature of a heat storage medium at an outlet of the heat storage heat exchanger (29).

  In this heat storage system, the temperature of the heat storage medium at the outlet of the heat storage heat exchanger (29) is in a supercooled state at a first predetermined temperature lower than the hydrate generation temperature. The temperature is surely undercooled below the hydrate formation temperature. Therefore, some hydrate slurry is surely present in the heat storage tank. Therefore, when the supercooled heat storage medium comes into contact with the already existing hydrate slurry by mixing, turbulent flow, and stirring in the heat storage tank accompanying the subsequent heating control (temperature shock) of the heat storage medium, The heat storage medium eliminates the supercooled state and becomes a hydrate slurry.

  Further, when the first predetermined temperature lower than the hydrate generation temperature is set to a predetermined temperature that is, for example, 3 ° C. lower than the hydrate generation temperature (supercooling = 3 ° C.), the heat storage of the heat storage heat exchanger It is possible to secure a large temperature difference between the inlet and outlet of the medium and to operate the heat storage heat exchanger with a good heat exchange rate.

  According to a third aspect of the present invention, in the heat storage system, the refrigerant circuit (11) includes an electric valve (30) disposed in a refrigerant supply passage (14a, 14b) to the heat storage heat exchanger (29). Then, after the sensible heat storage operation is completed, the operation control unit (100) changes the opening of the motor-operated valve (30) to the larger side, and the refrigerant in the heat storage heat exchanger (29) It is characterized by raising the temperature.

  In this heat storage system, during the heating operation, the opening degree of the motor-operated valve of the refrigerant circuit is changed to a larger side to raise the refrigerant temperature in the heat storage heat exchanger. Thereby, a heat storage medium can be heated moderately, mixing and stirring of heat storage media from which temperature differs are performed appropriately, and the supercooled state of a heat storage medium can be canceled reliably.

  According to a fourth aspect of the present invention, in the heat storage system, the operation control unit (100) is configured such that the heat storage medium temperature at the outlet of the heat storage heat exchanger (29) is higher than the hydrate generation temperature by the heating operation. 2 After the temperature reaches a predetermined temperature, the latent heat cool-down operation in the same manner as the sensible heat cool-down operation is performed.

  In this heat storage system, when the heat storage medium temperature at the outlet of the heat storage heat exchanger becomes the second predetermined temperature by the heating operation, the heating operation is stopped and the latent heat cold storage operation is performed. Therefore, the heating operation time of the heat storage medium can be shortened, and heat storage in the heat storage tank can be performed efficiently.

  An air conditioning system according to a fifth aspect of the present invention includes the heat storage system and a use side heat exchanger (25) disposed in the refrigerant circuit (11) of the heat storage system, and the cold heat stored in the heat storage tank (52). Is provided to the use side heat exchanger (25) to cool the target air-conditioned space.

  In this air conditioning system, the cold energy stored in the heat storage tank (52) of the heat storage system is given to the use side heat exchanger (25), and the target air-conditioned space is cooled well.

  As described above, according to the first invention, by applying a temperature shock to the heat storage medium that has been in the supercooled state in the heat storage tank, the supercooled state of the heat storage medium is reliably eliminated, and the hydrate slurry Therefore, it is not necessary to employ a device such as a seed ice generation device of a dynamic ice heat storage system, and the cost can be reduced. In addition, since the supercooled state can be eliminated in the heat storage tank, blockage of the pipe in the middle of the heat storage medium distribution pipe can be prevented.

  According to the second invention, since the hydrate slurry as a core for obtaining a large hydrate slurry for eliminating the supercooled state of the heat storage medium was originally present in the heat storage tank, It is possible to more reliably eliminate the overcooling state. Further, a high heat exchange rate in the heat storage heat exchanger can be secured.

  According to the third invention, the heat storage medium can be appropriately heated to give an appropriate temperature shock in the heat storage tank, and the supercooled state of the heat storage medium can be reliably eliminated.

  According to the fourth invention, since the heating operation time of the heat storage medium can be shortened, the heat storage efficiency to the heat storage tank can be ensured high, and the predetermined heat storage amount can be secured in almost the desired time.

  According to the fifth aspect, the target air-conditioned space can be favorably cooled using the cold energy stored in the heat storage system.

FIG. 1 is a configuration diagram of an air conditioning system. FIG. 2 is a diagram illustrating the refrigerant flow and the heat storage medium flow during the sensible heat storage operation, the latent heat storage operation, and the heating operation. FIG. 3 is a diagram illustrating the flow of the refrigerant and the flow of the heat storage medium during the first use cooling operation. FIG. 4 is a diagram illustrating the refrigerant flow and the heat storage medium flow during the second usage cooling operation. FIG. 5 is a diagram showing changes in the heat storage medium temperature and the refrigerant temperature at the outlet of the heat storage heat exchanger during the pull-down operation of the air conditioning system. FIG. 6 is a diagram showing the viscosities at two aqueous solution temperatures at various concentrations of an aqueous tetra-n-butylammonium bromide solution.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

<Embodiment>
FIG. 1 is a configuration diagram of an air conditioning system (10). As shown in FIG. 1, the air conditioning system (10) includes an air conditioner (20), a heat storage device (50), and a controller (100) (corresponding to an operation control unit).

  The heat storage device (50) includes a heat storage tank unit (51), an auxiliary heat exchanger (28), a heat storage heat exchanger (29), a heat storage expansion valve (30), a circulation pump (58), and other various valves. (32, 33, 34). The heat storage circuit (61) is configured by the devices included in the heat storage device (50).

  The air conditioner (20) includes an outdoor unit (20a) and an indoor unit (20b). Equipment included in each unit (20a, 20b) and some equipment of heat storage device (50) (specifically, auxiliary heat exchanger (28), heat storage heat exchanger (29), expansion for heat storage) A refrigerant circuit (11) is constituted by the valve (30) and other various valves (32, 33, 34).

  The controller (100) is for controlling the operation of the air conditioning system (10), and controls the compressor (21) of the refrigerant circuit (11) and the circulation pump (58) of the heat storage circuit (61). I do.

  Of the air conditioning system (10), the outdoor unit (20a) and the heat storage device (50) of the air conditioner (20) constitute a heat storage system (40) for storing cold energy in the heat storage tank unit (51).

<Configuration of refrigerant circuit>
The refrigerant circuit (11) is filled with a refrigerant (corresponding to a heat medium), and a refrigeration cycle is performed by circulating the refrigerant. As shown in FIG. 1, the refrigerant circuit (11) mainly includes a compressor (21), an outdoor heat exchanger (22), an outdoor expansion valve (23), an indoor expansion valve (24), and an indoor heat exchanger (25 ), A four-way switching valve (26), an auxiliary heat exchanger (28), a heat storage heat exchanger (29), and a heat storage expansion valve (30). The compressor (21), the outdoor heat exchanger (22), the outdoor expansion valve (23) and the four-way switching valve (26) are provided in the outdoor unit (20a), and the indoor expansion valve (24) and the indoor heat exchanger ( 25) is provided in the indoor unit (20b).

  The compressor (21) compresses and discharges the refrigerant. The compressor (21) is, for example, a variable capacity type, and the rotation speed (operation frequency) is variable by an inverter circuit (not shown).

  The outdoor heat exchanger (22) is connected to the four-way switching valve (26) through the pipe (12). The outdoor heat exchanger (22) is, for example, a cross fin and tube type, and when outdoor air is supplied by an outdoor fan (22a) provided in the outdoor unit (20a), heat of the outdoor air and the refrigerant is generated. Exchange.

  The outdoor expansion valve (23) is connected to the outdoor heat exchanger (22) via the pipe (13), and is connected to the indoor expansion valve (24) via the pipe (14a, 14b). The outdoor expansion valve (23) and the indoor expansion valve (24) are composed of, for example, electronic expansion valves, and adjust the refrigerant pressure by varying the opening.

  The indoor heat exchanger (25) is connected to the indoor expansion valve (24) via the pipe (15), and is connected to the four-way switching valve (26) via the pipe (16). The indoor heat exchanger (25) is, for example, a cross fin and tube type, and when indoor air is supplied by an indoor fan (25a) provided in the indoor unit (20b), the heat of the indoor air and the refrigerant Exchange.

  The four-way switching valve (26) has four ports. Specifically, the first port of the four-way switching valve (26) is connected to the discharge side of the compressor (21), and the second port of the four-way switching valve (26) is connected to the compressor (27) via the accumulator (27). 21) connected to the suction side. The third port of the four-way switching valve (26) is connected to the outdoor heat exchanger (22) through the pipe (12), and the fourth port of the four-way switching valve (26) is connected to the indoor through the pipe (16). Connected to heat exchanger (25). The four-way selector valve (26) has a connection state of each port in a first state (state indicated by a solid line in FIG. 1) or a second state (state indicated by a broken line in FIG. 1) depending on the operation type of the air conditioning system (10). ).

  The auxiliary heat exchanger (28) has a refrigerant side passage (28a) and a heat storage side passage (28b). The refrigerant side passage (28a) is located on the pipe (14a), that is, between the outdoor expansion valve (23) and the heat storage expansion valve (30), and the refrigerant flows inside. The heat storage side passage (28b) is connected in series to the heat storage circuit (61), and a heat storage medium (described later) flows through the heat storage side passage (28b). The auxiliary heat exchanger (28) performs heat exchange between the refrigerant and the heat storage medium.

  The heat storage heat exchanger (29) has a refrigerant side passage (29a) and a heat storage side passage (29b). The refrigerant side passage (29a) is located between the heat storage expansion valve (30) and the indoor expansion valve (24) on the pipe (14b), and the refrigerant flows inside. The heat storage side passage (29b) is connected in series to the heat storage circuit (61), and the heat storage medium flows inside. The heat storage heat exchanger (29) performs heat exchange between the refrigerant and the heat storage medium.

  The heat storage expansion valve (30) is connected to the auxiliary heat exchanger (28) via the pipe (14a), and is connected to the heat storage heat exchanger (29) via the pipe (14b). The heat storage expansion valve (30) is composed of, for example, an electronic expansion valve, and adjusts the pressure of the refrigerant by varying the opening degree.

  The refrigerant circuit (11) is provided with three on-off valves (31, 32, 33) and one check valve (34). The first on-off valve (31) is located on the first bypass pipe (17), and the second on-off valve (32) is located on the second bypass pipe (18). Here, the first bypass pipe (17) connects the pipe (12) and the outdoor expansion valve (23) and the auxiliary heat exchanger (28) in the pipe (14a). The second bypass pipe (18) connects the pipe (16) and the heat storage heat exchanger (29) and the indoor expansion valve (24) in the pipe (14b). The third on-off valve (33) is between the heat storage heat exchanger (29) and the indoor expansion valve (24) in the pipe (14b), and is also connected to the second bypass pipe (18) and the pipe (14b). It is located in the indoor expansion valve (24) side rather than the connection part. The check valve (34) is connected in parallel to the third on-off valve (33). When the refrigerant pressure on the indoor expansion valve (24) side of the third on-off valve (33) exceeds a predetermined value, the check valve (34) receives heat from the indoor expansion valve (24) (29) It is provided so that the refrigerant flows toward the) side.

<Configuration of heat storage circuit>
The heat storage circuit (61) is filled with a heat storage medium, and a cycle of storing the cold energy by circulating the heat storage medium is performed. The heat storage circuit (61) is mainly configured by the auxiliary heat exchanger (28) and the heat storage heat exchanger (29) described above, in addition to the heat storage tank unit (51) and the circulation pump (58).

  Here, the heat storage medium according to the first embodiment will be described. As the heat storage medium, a heat storage material in which clathrate hydrate is generated by cooling, that is, a heat storage material having fluidity is employed. Specific examples of the heat storage medium include tetranbutylammonium bromide (TBAB) aqueous solution, trimethylolethane (TME) aqueous solution, and paraffinic slurry. For example, an aqueous solution of tetra-n-butylammonium bromide maintains the state of the aqueous solution even in a supercooled state in which the temperature of the aqueous solution is lower than the hydrate formation temperature after being stably cooled. When an impact is applied, the supercooled solution changes to a solution containing clathrate hydrate (hydrate slurry). That is, the tetra-n-butylammonium bromide aqueous solution eliminates the supercooled state, and clathrate hydrates (hydrate crystals) composed of tetra-n-butylammonium bromide and water molecules are generated, resulting in a relatively viscous viscosity. High hydrate slurry. On the contrary, when the hydrate slurry of tetra-n-butylammonium bromide becomes higher than the hydrate formation temperature by heating, the clathrate hydrate melts and becomes a liquid state having a relatively high fluidity. In addition, the hydrate formation temperature of tetra n butyl ammonium bromide aqueous solution is higher than 0 degreeC, for example, 12 degreeC.

  As shown in FIG. 1, the heat storage tank unit (51) includes a heat storage tank (52), an inflow pipe (55), and an outflow pipe (56). The heat storage tank (52) is a hollow cylindrical container arranged such that the axial direction is the vertical direction, and the upper end and the lower end are closed. A heat storage medium is stored in the heat storage tank (52). A first opening (53) is formed in a lower portion of the side wall of the heat storage tank (52), and a first opening (53) is formed in the upper side of the tank (52) of the side wall of the heat storage tank (52). Two openings (54) are formed.

  As shown in FIG. 1, the inflow pipe (55) is attached to the heat storage tank (52) through the first opening (53), and allows the heat storage medium to flow into the heat storage tank (52). The inlet end of the heat storage medium of the inflow pipe (55) is connected to one end of the heat storage side passage (29b) of the heat storage heat exchanger (29) via the pipe (62). The outlet end of the heat storage medium of the inflow pipe (55) communicates with the inside of the heat storage tank (52).

  As shown in FIG. 1, the outflow pipe (56) is attached to the heat storage tank (52) via the second opening (54), and the heat storage medium inside the heat storage tank (52) is transferred from the tank (52). Spill. The inlet end of the heat storage medium of the outflow pipe (56) communicates with the heat storage tank (52). The outlet end of the heat storage medium of the outflow pipe (56) is connected to one end of the heat storage side passage (28b) of the auxiliary heat exchanger (28) via the pipe (63).

  The circulation pump (58) circulates the heat storage medium in the direction from the auxiliary heat exchanger (28) toward the heat storage heat exchanger (29) in the heat storage circuit (61) of FIG. The circulation pump (58) is connected to the other end of the heat storage side passage (28b) of the auxiliary heat exchanger (28) through the pipe (64), and is connected to the heat storage heat exchanger (29) through the pipe (65). Is connected to the other end of the heat storage side passage (29b). The controller (100) controls on / off of the operation of the circulation pump (58) and the conveyance amount of the heat storage medium.

  With the above configuration, the heat storage circuit (61) is a closed circuit.

<Operation of air conditioning system>
The operation types of the air conditioning system (10) are only the operation in which the heat storage medium is circulated in the heat storage circuit (61) in parallel with the refrigerant circulation in the refrigerant circuit (11), and the refrigerant circulation in the refrigerant circuit (11). It is roughly divided into driving. Below, the driving | operation operation | movement in the former case is demonstrated. As the former case, latent heat cold storage operation and utilization cooling operation can be mentioned.

―Cooling operation of latent heat―
In the latent heat cold storage operation shown in FIG. 2, the refrigerant condensed and cooled in the outdoor heat exchanger (22) and the auxiliary heat exchanger (28) enters the refrigerant side passage (29a) of the heat storage heat exchanger (29). As a result, the heat storage medium in the heat storage side passage (29b) is cooled and becomes supercooled, then flows into the heat storage tank (52) and becomes hydrate slurry and is stored in the heat storage tank (52). Is done. The refrigerant circuit (11) performs a refrigeration cycle in which the outdoor heat exchanger (22) serves as a condenser and the heat storage heat exchanger (29) serves as an evaporator. The heat storage circuit (61) is configured so that the heat storage medium flowing out of the heat storage tank (52) passes through the auxiliary heat exchanger (28) and the heat storage heat exchanger (29) in order, and flows into the heat storage tank (52) again. Circulate the heat storage medium.

  Specifically, the four-way selector valve (26) is set to the first state, the first on-off valve (31) and the third on-off valve (33) are set to the closed state, and the second on-off valve (32) is set to the open state. The opening of the outdoor expansion valve (23) is in a fully open state, the opening of the indoor expansion valve (24) is in a fully closed state, and the opening of the heat storage expansion valve (30) is a predetermined opening (heat storage heat exchanger (29 ), The degree of superheat of the refrigerant at the outlet of the refrigerant side passage (29a) is set to a predetermined target value. The compressor (21) and the outdoor fan (22a) operate.

  The refrigerant discharged from the compressor (21) flows into the outdoor heat exchanger (22) through the pipe (12), dissipates heat to the outdoor air and condenses in the outdoor heat exchanger (22). The condensed refrigerant flows into the refrigerant side passage (28a) of the auxiliary heat exchanger (28) through the outdoor expansion valve (23), but while passing through the refrigerant side passage (28a), the heat storage side passage (28b ) Is further cooled by the heat storage medium flowing through. The refrigerant flowing out of the auxiliary heat exchanger (28) is depressurized by the heat storage expansion valve (30), and then absorbs heat from the heat storage medium and evaporates by the heat storage heat exchanger (29). The evaporated refrigerant is once sucked into the accumulator (27) through the second bypass pipe (18) and the four-way switching valve (26), and then sucked into the compressor (21) and compressed.

  In the heat storage circuit (61), the circulation pump (58) operates. The heat storage medium in the heat storage tank (52) flows into the heat storage side passage (28b) of the auxiliary heat exchanger (28) through the second opening (54) and the pipes (56, 63). While passing through the heat storage side passage (28b), the heat storage medium is heated by the refrigerant flowing through the refrigerant side passage (28a). The heated heat storage medium flows into the heat storage side passage (29b) of the heat storage heat exchanger (29) through the circulation pump (58) and the pipes (64, 65). While passing through the heat storage side passage (29b), the heat storage medium is cooled to a temperature lower than the hydrate generation temperature by the refrigerant flowing through the refrigerant side passage (29a) and is in a supercooled state. The supercooled heat storage medium flows into the heat storage tank (52) through the pipes (62, 55) and the first opening (53). In the heat storage tank (52), if a lot of hydrate slurry already exists, the supercooled heat storage medium (that is, the supercooled solution) comes into contact with the existing hydrate slurry. The supercooled state is eliminated and a hydrate slurry is obtained. In this way, a lot of hydrate slurry is generated in the heat storage tank (52), and cold heat is stored.

―Cooling operation―
In the utilization cooling operation shown in FIGS. 3 and 4, the hydrate slurry stored in the heat storage tank (52) in the latent heat storage operation is used as a cold heat source, and the indoor heat exchanger (25) The air conditioning is equivalent to the target space. The refrigerant circuit (11) circulates the refrigerant so that the refrigerant obtained from the heat storage medium in the heat storage heat exchanger (29) evaporates in the indoor heat exchanger (25). The heat storage circuit (61) is configured so that the heat storage medium flowing out of the heat storage tank (52) passes through the auxiliary heat exchanger (28) and the heat storage heat exchanger (29) in order, and flows into the heat storage tank (52) again. Circulate the heat storage medium.

  The utilization cooling operation includes a first utilization cooling operation in FIG. 3 and a second utilization cooling operation in FIG.

-First use cooling operation-
In the first use cooling operation, indoor cooling is performed using the cold heat stored in the heat storage tank (52) and the cold heat obtained by the refrigeration cycle of the refrigerant circuit (11). In the refrigerant circuit (11), the outdoor heat exchanger (22) is a condenser, the auxiliary heat exchanger (28) and the heat storage heat exchanger (29) are subcoolers (that is, radiators), and the indoor heat exchanger (25 ) Performs a refrigeration cycle that becomes an evaporator.

  Specifically, as shown in FIG. 3, the four-way switching valve (26) is in the first state, the first on-off valve (31) and the second on-off valve (32) are closed, and the third on-off valve (33) is Each is set to the open state. The opening degree of the outdoor expansion valve (23) and the heat storage expansion valve (30) is fully open, and the opening degree of the indoor expansion valve (24) is a predetermined opening degree (the degree of superheat of the refrigerant at the outlet of the indoor heat exchanger (25)). Is set to a predetermined target value). The compressor (21), the outdoor fan (22a), and the indoor fan (25a) operate.

  The refrigerant discharged from the compressor (21) flows into the outdoor heat exchanger (22) through the pipe (12), dissipates heat to the outdoor air and condenses in the outdoor heat exchanger (22). The condensed refrigerant flows into the refrigerant side passage (28a) of the auxiliary heat exchanger (28) via the outdoor expansion valve (23) that is fully open, and the refrigerant side passage (28a) of the auxiliary heat exchanger (28). Is further cooled by the heat storage medium flowing through the heat storage side passageway (28b). The refrigerant that has flowed out of the auxiliary heat exchanger (28) flows into the refrigerant side passage (29a) of the heat storage heat exchanger (29) via the heat storage expansion valve (30) that is fully open, and the heat storage side passage (29b ) Is further cooled by the heat storage medium flowing through. The refrigerant is depressurized by the indoor expansion valve (24), and then absorbs heat from the indoor air by the indoor heat exchanger (25) to evaporate. Thereby, indoor air is cooled. The evaporated refrigerant is once sucked into the accumulator (27) through the pipe (16) and the four-way switching valve (26), and then sucked into the compressor (21) and compressed.

  In the heat storage circuit (61), the circulation pump (58) operates. The heat storage medium in the heat storage tank (52) flows into the heat storage side passage (28b) of the auxiliary heat exchanger (28) through the second opening (54) and the pipes (56, 63). While passing through the heat storage side passage (28b), the heat storage medium absorbs heat from the refrigerant flowing through the refrigerant side passage (28a). The heat storage medium that has absorbed heat flows into the heat storage side passageway (29b) of the heat storage heat exchanger (29) through the circulation pump (58) and the pipes (64, 65). While passing through the heat storage side passage (29b), the heat storage medium further absorbs heat from the refrigerant flowing through the refrigerant side passage (29a). Further, the heat storage medium that has absorbed heat flows into the heat storage tank (52) through the pipes (62, 55) and the first opening (53). In this way, cold heat is applied from the heat storage medium to the refrigerant.

-Second use cooling operation-
In the second usage cooling operation, indoor cooling is performed using only the cold energy stored in the heat storage tank (52). The refrigerant circuit (11) circulates the refrigerant so that the refrigerant that has passed through the heat storage heat exchanger (29) evaporates in the indoor heat exchanger (25).

  Specifically, as shown in FIG. 4, the four-way switching valve (26) is in the first state, the second on-off valve (32) is in the closed state, and the first on-off valve (31) and the third on-off valve (33) are Each is set to the open state. The opening of the outdoor expansion valve (23) is fully closed, the opening of the heat storage expansion valve (30) is fully open, and the opening of the indoor expansion valve (24) is a predetermined opening (indoor heat exchanger (25) The opening degree at which the degree of superheat of the refrigerant at the outlet becomes a predetermined target value). The compressor (21) and the indoor fan (25a) operate.

  The refrigerant discharged from the compressor (21) flows into the refrigerant side passage (28a) of the auxiliary heat exchanger (28) through the pipe (12), the first bypass pipe (17) and the pipe (14), The heat storage medium flowing through the heat storage side passage (28b) dissipates heat and condenses. The condensed refrigerant passes through the heat storage expansion valve (30) that is fully open, then flows into the refrigerant side passage (29a) of the heat storage heat exchanger (29), and passes through the refrigerant side passage (29a). And further cooled by the heat storage medium flowing through the heat storage side passageway (29b). Thereafter, the refrigerant flows into the indoor expansion valve (24) through the third on-off valve (33) and is depressurized. The decompressed refrigerant absorbs heat from the room air and evaporates while passing through the indoor heat exchanger (25). Thereby, indoor air is cooled. The evaporated refrigerant is once sucked into the accumulator (27) through the pipe (16) and the four-way switching valve (26), and then sucked into the compressor (21) and compressed.

  In the heat storage circuit (61), the circulation pump (58) operates. The heat storage medium in the heat storage tank (52) consists of the second opening (54), piping (56, 63), the heat storage side passage (28b) of the auxiliary heat exchanger (28), piping (64), and circulation pump (58) After flowing through the pipe (65) in this order, it flows into the heat storage side passage (29b) of the heat storage heat exchanger (29). While passing through each heat storage side passage (28b, 29b), the heat storage medium absorbs heat from the refrigerant passing through each refrigerant side passage (28a, 29a). The heat storage medium that has absorbed heat flows into the heat storage tank (52) through the pipes (62, 55) and the first opening (53). In this way, cold heat is applied from the heat storage medium to the refrigerant.

<Pull-down operation>
Pull-down operation in which the heat storage medium generates a hydrate slurry in the heat storage tank (52) from the initial state where the heat storage medium is at a predetermined temperature (for example, 20 ° C) that greatly exceeds the hydrate generation temperature (12 ° C). explain.

  FIG. 5 shows the temperature change of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) and the refrigerant temperature change in the refrigerant side passage (29a) during the pull-down operation. FIG. 5 illustrates the case where a tetra-n-butylammonium bromide (TBAB) solution is used as a heat storage medium.

  At the time of this pull-down operation, the controller (100) initially performs a sensible heat cold storage operation in the same manner as the latent heat cold storage operation. By continuing this sensible heat storage operation, the heat storage medium is cooled in the heat storage heat exchanger (29), and the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) is The temperature gradually decreases from a predetermined temperature (20 ° C.).

  Due to the sensible heat storage operation, the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) reaches its hydrate formation temperature (12 ° C), and the temperature is further lowered to a predetermined level. When the temperature (first predetermined temperature, for example, 9 ° C) is reached, the heat storage medium at the outlet of the heat storage side passage (29b) becomes a supercooled solution in a supercooled state having a supercooling degree of 3 ° C. In this state, in the whole or most of the heat storage circuit (61) including the heat storage heat exchanger (29) and the heat storage tank (52), the temperature of the heat storage medium is lower than the hydrate formation temperature (12 ° C). It has become.

  At this point, the controller (100) stops the sensible heat storage operation and executes a heating operation for heating the heat storage medium. By this heating operation, as described later, a temperature shock is given to the heat storage medium in the heat storage tank (52), and the hydrate slurry is reliably grown in the heat storage tank (52), so that the heat storage medium is supercooled. Eliminate.

  Here, the reason for stopping the sensible heat storage operation when the degree of supercooling is 3 ° C. is as follows. That is, as can be seen from FIG. 5, in the period of short duration from the start of the sensible heat storage operation, the decrease in the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) is It is remarkable, and the heat exchange rate of the heat storage heat exchanger (29) is high. On the other hand, in the period before the sensible heat storage operation is stopped, the temperature decrease gradually decreases, and the heat exchange rate of the heat storage heat exchanger (29) decreases. Therefore, if the degree of supercooling when the sensible heat storage operation is stopped is set lower than 3 ° C, the heat exchange rate of the heat storage heat exchanger (29) becomes extremely low, and the target amount to the heat storage tank (52) This is because it becomes impossible to secure the heat storage in the desired time.

  The heating operation after completion of the sensible heat storage operation is an operation of heating the heat storage medium of the heat storage circuit (61) with the refrigerant of the refrigerant circuit (11). The details of this heating operation are as follows.

-Heating operation-
In this heating operation, the opening degree of the heat storage expansion valve (corresponding to an electric valve) (30) is set to the predetermined opening degree during the sensible heat storage operation (the outlet of the refrigerant side passage (29a) of the heat storage heat exchanger (29)). The same operation as the sensible heat regenerative operation according to FIG. 2 is performed except that the degree of superheat of the refrigerant is changed to an opening degree side (including full opening) larger than an opening degree at which the refrigerant becomes a predetermined target value.

  That is, after the refrigerant discharged from the compressor (21) is condensed in the outdoor heat exchanger (22), the outdoor expansion valve (23), the refrigerant side passage (28a) of the auxiliary heat exchanger (28), The heat storage expansion valve (30), the refrigerant side passage (29a) of the heat storage heat exchanger (29), and the second bypass pipe (18) flow in this order. In particular, since the heat storage expansion valve (30) has an opening larger than the predetermined opening, the refrigerant flowing out of the auxiliary heat exchanger (28) can be piped (supply passage) without being decompressed or with little decompression. ) (14a, 14b) and then flows into the heat storage heat exchanger (29). Therefore, the temperature of the refrigerant flowing through the refrigerant side passage (29a) of the heat storage heat exchanger (29) during the heating operation rapidly rises from the temperature of the refrigerant flowing in the sensible heat storage operation as shown by the broken line in FIG. However, it becomes higher than the hydrate formation temperature (12 ° C.) of the heat storage medium. The refrigerant flowing through the heat storage heat exchanger (29) is then sucked into the compressor (21) via the four-way switching valve (26) and the accumulator (27).

  In the heat storage circuit (61), the heat storage medium flowing out of the heat storage tank (52) and flowing into the heat storage side passage (28b) of the auxiliary heat exchanger (28) absorbs heat from the refrigerant flowing through the refrigerant side passage (28a), It flows into the heat storage side passageway (29b) of the heat storage heat exchanger (29). Since the temperature of the refrigerant flowing through the refrigerant side passage (29a) is higher than the hydrate formation temperature (12 ° C) of the heat storage medium as described above, the temperature of the heat storage medium flowing through the heat storage side passage (29b) is as shown in FIG. As shown by the solid line, the temperature rises above the hydrate formation temperature (12 ° C.).

  As shown in FIG. 5, during the heating operation, the refrigerant temperature in the refrigerant side passage (29a) of the heat storage heat exchanger (29) rapidly rises. At the same time, the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) rises rapidly from the temperature (9 ° C) and exceeds the hydrate formation temperature (12 ° C) at a predetermined temperature. (Second predetermined temperature, for example, 18 ° C.). The heat storage medium having increased in temperature flows from the heat storage side passage (29b) of the heat storage heat exchanger (29) into the heat storage tank (52) through the pipes (62, 55).

  Here, a heat storage medium such as a tetra-n-butylammonium bromide (TBAB) aqueous solution has a characteristic that the viscosity decreases as the temperature increases. Therefore, in the heat storage tank (52), the high-viscosity heat storage medium already present in the supercooled state (temperature = 9 ° C.) and the low-viscosity heat storage medium in the high temperature (18 ° C.) that has flowed in. Are mixed at once to make the viscosity uniform, and a turbulent flow is suddenly generated to stir the heat storage tank (52). As a result, many heat storage media come into contact with the hydrate slurry already present in the heat storage tank (52), and the hydrate slurry grows greatly.

  As described above, when the high-temperature heat storage medium flows into the heat storage tank (52) and a temperature shock occurs in the heat storage tank (52), the above-mentioned mixing, turbulence, and stirring of the heat storage medium occur. It is considered that the difference in viscosity between the heat storage media at different temperatures affects the degree of mixing, turbulence, and stirring. For this reason, the present inventors prepared three types (10%, 20%, 40%) of tetra-n-butylammonium bromide (TBAB) aqueous solution having a concentration as shown in FIG. Was adjusted to 10 ° C and 20 ° C, and the viscosity of the TBAB aqueous solution at each temperature was measured. As can be seen from the figure, the viscosity difference is 0.6 mPa · s at 10% concentration, the viscosity difference is 1.0 mPa · s at 20% concentration, and the viscosity difference is 3.9 mPa · s at 40% concentration. From the above, when the TBAB aqueous solution is used as a heat storage medium, under the same temperature difference, the higher the concentration, the greater the viscosity difference. Therefore, the mixing, turbulent flow, and stirring in the heat storage tank (52) The degree is large, and it is considered that the heat storage medium can easily eliminate the supercooled state.

  From the start of the heating operation, the heat storage medium temperature at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) reaches a predetermined temperature (18 ° C) exceeding the hydrate formation temperature (12 ° C). The time until (that is, the duration of the heating operation) is a short time, for example, 0.5 to 1.0 minutes.

  As described above, when the heat storage medium temperature reaches the high temperature (18 ° C.), the controller (100) rapidly increases the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29). So that the opening degree of the heat storage expansion valve (corresponding to an electric valve) (30) is the predetermined opening degree (the degree of superheat of the refrigerant at the outlet of the refrigerant side passage (29a) of the heat storage heat exchanger (29) is predetermined). The opening is set to be much smaller than the target opening). As a result, the refrigerant temperature at the outlet of the refrigerant side passage (29a) and the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) rapidly decrease to near the temperature during the sensible heat storage operation. To do. As shown in FIG. 5, this temperature decrease period is a stabilization waiting period until the temperature of the refrigerant and the heat storage medium is stabilized after the heating operation.

After the stabilization waiting period, the latent heat cold storage operation is performed so as to maintain the heat storage medium temperature (9 ° C.) at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29). Therefore, after the heat storage medium flowing out from the heat storage side passage (29b) of the heat storage heat exchanger (29) is in a supercooled state at a temperature (9 ° C), the supercooled heat storage medium is converted into a heat storage tank (52 When the heat storage medium in the supercooled state comes into contact with the grown hydrate slurry, the supercooled state is surely eliminated and the hydrate slurry is repeated.
-Effect of the embodiment-
In the present embodiment, during the pull-down operation, the heat storage medium is brought into a supercooled state (supercooling degree = 3 ° C) at a temperature (9 ° C), and then the heating operation is performed to store the heat storage medium in the heat storage tank (52). Since a hydrate slurry was generated in the heat storage tank (52) by applying a temperature shock to the heat storage tank (52), the supercooled heat storage medium flowing into the heat storage tank (52) was then generated as described above. When it comes into contact with the slurry, the supercooled state is surely canceled and a hydrate slurry is repeated. Therefore, cold heat can be reliably stored in the heat storage tank (52) by performing only one heating operation during the pull-down operation.

  In addition, since the heating operation can be performed only by changing the opening degree of the heat storage expansion valve (30) to the large opening side, a device such as a seed ice generation device of a conventional dynamic ice heat storage system is unnecessary. Cost reduction is possible.

  In the present embodiment, the sensible heat storage operation at the beginning of the pull-down operation is such that the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) is less than the hydrate generation temperature (12 ° C). This is continued until the predetermined temperature (9 ° C.) is reached. Therefore, since almost all of the heat storage medium in the heat storage tank (52) can be brought into a supercooled state below the hydrate formation temperature (12 ° C), even if the hydrate slurry is small in the heat storage tank (52). Certainly exists. Therefore, at the time of a temperature shock due to the subsequent heating operation, in the heat storage tank (52), the hydrate slurry can be greatly grown with the existing hydrate slurry as a core, and then the heat storage tank (52) The supercooled state of the inflowing heat storage medium can be reliably eliminated.

  Further, in the present embodiment, during the heating operation, the heat storage at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) is performed only by changing the opening of the heat storage expansion valve (30) to the large opening side. Since the medium temperature can be rapidly increased from a temperature (9 ° C.) below the hydrate formation temperature (12 ° C.) to a temperature (18 ° C.) above the hydrate formation temperature, the heat storage medium during this heating operation The amount of heating applied to can be made appropriate.

  In addition, when the temperature of the heat storage medium at the outlet of the heat storage side passage (29b) of the heat storage heat exchanger (29) suddenly rises to a high temperature (18 ° C), the opening degree of the heat storage expansion valve (30) is increased. Since the heat storage medium temperature is returned to near the supercooled temperature (9 ° C) by narrowing down from the large opening value, the opening of the heat storage expansion valve (30) is increased to the predetermined opening during sensible heat storage operation. The continuation time of the heating operation set to an opening degree exceeding can be limited to a short time of 0.5 to 1.0 minutes as described above. Accordingly, the influence of the heating operation on the heat storage efficiency to the heat storage tank (52) can be reduced, and a target amount of cold can be stored in the heat storage tank (52) in a substantially desired time.

(Other embodiments)
In the above embodiment, during the heating operation, the opening degree of the heat storage expansion valve (30) is changed to the large opening side, and the refrigerant temperature in the refrigerant side passage (29a) of the heat storage heat exchanger (29) is increased to store heat. The medium is heated and the refrigerant cycle of the refrigerant circuit (11) is the same as the sensible heat storage operation (forward cycle), but the refrigerant cycle is the reverse cycle, and the amount of heat absorbed by the indoor heat exchanger (25) is stored. The heat storage medium may be heated by being applied to the heat storage medium through the heat storage side passageway (29b) of the heat exchanger (29). Whether the refrigerant circuit (11) is set to the forward or reverse cycle during the heating operation depends on the capacity of the heat storage tank (52), mixing, turbulent flow, and stirring during the temperature shock in the heat storage tank (52). It is only necessary to select an appropriate one in consideration of the situation.

  Moreover, in the said embodiment, although tetra n butyl ammonium bromide (TBAB) aqueous solution was used as a thermal storage medium, of course, you may use another thermal storage medium.

  Furthermore, although the heat storage circuit (61) illustrated the circuit provided with the auxiliary heat exchanger (28) as shown in FIG. 1, a various circuit may be employ | adopted for a heat storage circuit.

  As described above, since the present invention can reliably store chilled heat from a supercooled state in a heat storage tank from a supercooled state in a heat storage medium in which clathrate hydrate is produced by cooling, the heat storage system And it is useful as an air conditioning system using this.

10 Air-conditioning system 11 Refrigerant circuit 14a, 14b Piping (supply passage)
25 Use-side heat exchanger 29 Heat storage heat exchanger 30 Heat storage expansion valve (motorized valve)
40 heat storage system 52 heat storage tank 61 heat storage circuit 100 controller (operation control unit)

Claims (5)

A heat storage tank (52) for storing a heat storage medium in which clathrate hydrate is generated by cooling, and a heat storage circuit (61) for circulating the heat storage medium;
A refrigerant circuit (11) for circulating the refrigerant;
A heat storage heat exchanger that is arranged in common to the heat storage circuit (61) and the refrigerant circuit (11) and exchanges heat between the refrigerant of the refrigerant circuit (11) and the heat storage medium of the heat storage circuit (61). (29) a heat storage system comprising:
An operation control unit (100) for controlling the operation of storing heat in the heat storage tank (52),
The operation control unit (100)
After performing a sensible heat storage operation for cooling the heat storage medium in the heat storage heat exchanger (29) so that the heat storage medium of the heat storage circuit (61) is set to a first predetermined temperature lower than the hydrate generation temperature. ,
A heat storage system that performs a heating operation of heating the heat storage medium by the heat storage heat exchanger (29) so that the heat storage medium of the heat storage circuit (61) is equal to or higher than the hydrate formation temperature. In claim 1,
The first predetermined temperature is a temperature of a heat storage medium at an outlet of the heat storage heat exchanger (29). In claim 2,
The refrigerant circuit (11) includes an electric valve (30) disposed in a refrigerant supply passage (14a, 14b) to the heat storage heat exchanger (29),
The operation control unit (100)
After completion of the sensible heat storage operation, the opening degree of the motor-operated valve (30) is changed to a larger side, and the temperature of the refrigerant in the heat storage heat exchanger (29) is increased. . In claim 3,
The operation control unit (100)
After the heat storage medium temperature at the outlet of the heat storage heat exchanger (29) reaches a second predetermined temperature equal to or higher than the hydrate generation temperature by the heating operation, the latent heat cold storage operation in the same mode as the sensible heat cold storage operation is performed. A heat storage system characterized by The heat storage system according to any one of claims 1 to 4,
Having a use side heat exchanger (25) arranged in the refrigerant circuit (11) of the heat storage system,
An air conditioning system characterized in that the cold air stored in the heat storage tank (52) is given to the use side heat exchanger (25) to cool the target air-conditioned space.

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