JP2007205628A - Hot water supply device, and heat storage and dissipation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot water supply device capable of efficiently storing heat of a heat source unit by preventing dropping of a heat exchange amount along with passage of time during heat storage. <P>SOLUTION: A latent heat storage material to be used becomes a supercooled state during heat dissipation operation, and it can maintain fluidity even when supercooling is canceled and a solid phase is deposited. In a heat storage unit, a supercooling cancel device is provided for canceling the supercooled state when the latent heat storage material becomes the supercooled state. When storing heat in the heat storage unit, latent heat storage material of a low temperature side of the latent heat storage material temperature-stratified in the heat storage unit is supplied to the heat source device, and when dissipating heat of the heat storage unit, latent heat storage material of a high temperature side of the latent heat storage material temperature-stratified in the heat storage unit is supplied to a hot water supply unit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot water supply apparatus and a heat storage and dissipation method.

  2. Description of the Related Art Conventionally, hot water supply apparatuses have been developed that use an engine, a fuel cell, a heat pump cycle, or the like as a heat source unit, and generate hot water by heating tap water or the like using the heat of the heat source unit.

  When using a heat source unit driven by electric power among such hot water supply apparatuses, nighttime electric power is often used to drive the heat source unit in order to reduce costs. However, when warm energy is generated using nighttime power, it is necessary to store it until the day when warm water is actually used.

  In addition, when an engine or fuel cell is used as a heat source unit, it is so-called cogeneration that drives them to generate motive power or electric power and uses the heat generated at the same time. And even when the demand times of heat do not match, it is necessary to store the generated heat.

  Conventionally, water is generally used for heat storage. However, when water is used as a heat storage material, heat is stored with the sensible heat, so the heat capacity per unit volume is not sufficient, and the problem arises that the heat storage container is enlarged.

In order to solve such a problem, an apparatus that uses a latent heat storage material having a large amount of latent heat accompanying a phase change instead of water is disclosed. (For example, patent document 1). By utilizing the latent heat accompanying the phase change, the heat capacity per unit volume can be increased compared to the heat storage by sensible heat of water, and the heat storage tank can be made compact.
JP 2001-207163 A

  During the heat storage operation to the heat storage unit, the heat storage material is supplied with heat from the heat source unit and heated. Conversely, when viewed from the heat source unit side, it is cooled by the heat storage material. In general, the efficiency of a heat source unit decreases when cooling is insufficient.

  In the case of the heat pump cycle, the heat output per input energy, that is, the COP decreases. In particular, in the case of a heat pump cycle using carbon dioxide as a refrigerant, the carbon dioxide refrigerant at the time of compression is in a supercritical state, so that the reduction of COP becomes significant.

  Also, in the engine and the fuel cell, when the cooling is insufficient, the output is reduced, the fuel consumption rate is deteriorated, and further, the apparatus is broken down.

  Here, FIG. 1 is a schematic diagram showing a partial configuration of a hot water supply apparatus using a conventional latent heat storage material.

  As shown in FIG. 1, in general, when a hot water supply apparatus is configured using a latent heat storage material, the heat storage material 100 is placed in the heat storage tank 101, and the heat exchanger 102 (generally installed in the heat storage tank 101) In this case, a high-temperature heat medium supplied from the heat source unit 103 is circulated through the tube to exchange heat with the heat storage material 100.

  In this case, when the temperature of the latent heat storage material 100 increases during heat storage, the amount of heat exchanged between the heat medium and the latent heat storage material 100 decreases, and the heat medium passes through the heat exchanger 102. However, the temperature is not sufficiently low, and as a result, the cooling of the heat source unit 103 becomes insufficient and the efficiency of the heat source unit decreases.

  The heat medium is a substance that retains and transports heat generated by the heat source unit. Generally hot water or steam is often used. When the heat source unit is a heat pump unit, hot water that has exchanged heat with a high-temperature refrigerant is often used as the heat medium, but the working refrigerant itself can be used as the heat medium.

  FIG. 2 is a schematic diagram for easily explaining this problem.

  FIGS. 2 (1) to (6) schematically show changes over time in the temperature of the latent heat storage material and the heat medium that exchanges heat with the latent heat storage material when the latent heat storage material stores heat.

  In addition, FIG. 2 (1) is a heat storage start time, and it changes from FIG. 2 (1) to (6) with progress of time. Moreover, in each figure of FIG. 2, in the heat storage tank filled with the latent heat storage material, the heat medium passes through the heat exchanger installed in the heat storage tank from the upper end to the lower end of the heat storage tank. Assuming the heat exchange between the heat medium and the latent heat storage material, the vertical locations of the heat storage tank 1 in this case (for example, the vicinity of the upper end and the vicinity of the lower end) are represented on the vertical axis, and the latent heat storage at each location The temperature of each material and heat medium is shown on the horizontal axis.

  FIG. 2 (1) shows the start of heat storage. At the start of heat storage, the latent heat storage material exhibits a uniform temperature Tpcm-i from the upper end to the lower end of the heat storage tank, and this temperature is sufficiently low with respect to the heat medium. Therefore, when the heat medium heated by the heat source unit is introduced from the upper end side, the latent heat storage material and the heat medium exchange heat with each other, and the heat medium is sufficiently cooled and discharged from the lower end of the heat storage tank.

  FIG. 2 (2) shows the time when a predetermined time has passed since (1). Since the temperature of the latent heat storage material near the upper end of the heat storage tank into which the high-temperature heat medium heated by the heat source unit is introduced is slightly increased, the average temperature difference between the heat medium and the latent heat storage material is reduced, The amount of heat exchange is reduced. As a result, the heat medium is discharged from the lower end of the heat storage tank in a state where the temperature is higher than (1) (that is, the outlet temperature of the heat medium is increased).

  FIG. 2 (3) shows the time when a predetermined time has passed since (2). Since a predetermined time has elapsed since the introduction of the high-temperature heat medium heated by the heat source unit, the temperature of the latent heat storage material near the upper end of the heat storage tank further rises and reaches the melting point Tm of the latent heat storage material, Part of the part begins to melt. As a result, the heat exchange amount as a whole further decreases, and the outlet temperature of the heat medium further increases accordingly.

  FIG. 2 (4) shows a time when a predetermined time has passed since (3). Since more time has passed since the introduction of the high-temperature heat medium heated by the heat source unit, about half of the latent heat storage material in the heat storage tank reaches the melting point Tm and melting proceeds. As a result, the heat exchange amount as a whole further decreases, and the outlet temperature of the heat medium further increases accordingly.

  FIG. 2 (5) shows a time when a predetermined time has passed since (4). Since a considerable amount of time has elapsed since the introduction of the high-temperature heat medium heated by the heat source unit, most of the latent heat storage material in the heat storage tank reaches the melting point Tm, and further near the upper end of the heat storage tank. In the latent heat storage material positioned, the phase change to liquid is completed and the temperature starts to rise. As a result, the temperature difference from the introduced heat medium is almost eliminated, heat exchange is not performed efficiently, and the outlet temperature of the heat medium continues to rise further.

  FIG. 2 (6) shows a state in which all of the latent heat storage material is melted, that is, when the heat storage is completed. In this state, all the latent heat storage materials in the heat storage tank are equal to or higher than the melting point Tm, all the heat storage materials become liquid, and the temperature rise further proceeds. As a result, the temperature difference between the introduced heat medium and the latent heat storage material is almost eliminated, and the heat medium is discharged with little heat exchange. At this time, the heat medium outlet temperature is higher than the melting point Tm of the latent heat storage material.

  This is a problem that the amount of heat exchange with the latent heat storage material described above is reduced.

  Further, as described above, when the heat storage is completed, the heat medium discharge temperature is higher than the heat storage material melting point Tm. This temperature difference (dT1 = To−Tm) between the heat medium discharge temperature To and the heat storage material melting point Tm is indispensable for heat exchange.

  The aforementioned Patent Document 1 refers to the problem, and in order to solve this problem, two types of latent heat storage materials having different melting points are used, and the outlet temperature of the heat medium is lowered by arranging them in series. . That is, the heat medium discharged in FIG. 2 (6) is further introduced into a heat storage tank filled with another latent heat storage material having a lower melting point (low temperature side latent heat storage material) to exchange heat with the refrigerant. Is going.

However, this method is not a fundamental solution to the problem that the amount of heat exchange decreases as the temperature of the latent heat storage material increases. In other words, in this method, it is inevitable that the outlet temperature of the heat medium eventually becomes higher than the melting point of the latent heat storage material over time, and yet the outlet temperature of the heat medium is sufficiently reduced. However, it is necessary to use a latent heat storage material having a melting point at a considerably low temperature. However, when hot water is generated using heat radiation from the latent heat storage material, in order to effectively use the amount of heat stored in the low temperature side latent heat storage material, the melting point Tm of the low temperature side latent heat storage material is heated. Only the temperature difference necessary for heat exchange needs to be higher than the water supply temperature Ti of the water to be made. If the required temperature difference at this time is dT2,
Ti + dT2 ≦ Tm
And as mentioned above,
Tm + dT1 ≦ To
Therefore, Ti + dT1 + dT2 ≦ To
It becomes. That is, in the case of Patent Document 1, the heat medium discharge temperature To is higher than the water supply temperature Ti by at least dT1 + dT2.

  The present invention has been made in view of such a situation, and in a hot water supply apparatus including a heat storage unit using a latent heat storage material, the amount of heat exchange does not decrease with the passage of time during heat storage. A main object is to provide a hot water supply device that can efficiently store and dissipate heat from the heat source unit, and to provide a heat storage and heat dissipation method suitable for the hot water supply device.

  The present invention for solving the above problems includes a heat source unit, a heat storage unit capable of storing and dissipating heat of the heat source unit, and a hot water supply unit for producing hot water using heat stored in the heat storage unit. The heat storage unit is in a supercooled state during heat radiation operation and maintains a liquid phase state, and can maintain fluidity even when supercooling is released and a solid phase is precipitated, and temperature stratification is possible. A latent heat storage material is used, and the heat storage unit is provided with a supercooling release device for canceling the supercooling state when the latent heat storage material is in a supercooling state, When storing heat in the heat storage unit, the latent heat storage material circulates between the heat source unit and the heat storage unit, and at that time, the latent heat storage material on the low temperature side in the latent heat storage material temperature-stratified by the heat storage unit is used as the heat source. On the other hand, when radiating heat from the heat storage unit, the latent heat storage material circulates between the heat storage unit and the hot water supply unit, and at that time, in the latent heat storage material temperature stratified by the heat storage unit A latent heat storage material on the high temperature side is supplied to the hot water supply unit, and the overcooling latent heat storage material existing in the heat storage unit is released by operating the overcool release device. It is a hot water supply device characterized by being possible.

  Moreover, in the said hot water supply apparatus, you may form the said latent heat storage material with the composition shifted from the eutectic composition in which the eutectic mixture which consists of a several component produces a eutectic.

  Furthermore, in the hot water supply device, the heat source unit is a heat pump unit that uses carbon dioxide as a refrigerant and includes a heat source side heat exchanger, an expansion valve, an evaporator, and a compressor. May be.

  Further, another invention that solves the above problem is that a supercooled state is maintained during heat dissipation and the liquid phase state is maintained, and even when the supercooling is released and the solid phase is precipitated, the fluidity can be maintained, and temperature stratification is performed. In the heat storage stage, the heat from the heat source is stored in the latent heat storage material, and in the heat release stage, the stage is the first heat release stage. In the first heat release stage, the latent heat storage material is supercooled, and then the subcooled latent heat storage material is intentionally released when the first heat release stage is almost completed. Then, in the second heat radiation step, the latent heat storage material released from the supercooling is further radiated to dissipate heat.

  In the present invention, the time of heat dissipation operation refers to the time of operation where heat is released from the high-temperature latent heat storage material to lower the temperature (that is, hot water is generated), and the time of heat storage operation refers to heat supplied to the low-temperature latent heat storage material. This refers to the time of operation when the temperature is supplied to increase the temperature (that is, the heat of the heat source unit is accumulated in the latent heat storage material). Therefore, as will be described later, the latent heat storage material of the apparatus of the present invention during the heat dissipation operation moves to be extracted from the high temperature side of the heat storage unit and returned to the low temperature side, while the apparatus of the present invention during the heat storage operation The latent heat storage material moves out from the low temperature side in the heat storage unit and returns to the high temperature side.

  The latent heat storage material that has been used in conventional water heaters is a fixed type that remains in the heat storage tank, and is also supplied from the heat source unit to a heat exchanger (generally a tube) installed in the heat storage tank. A high-temperature heat medium is circulated to exchange heat with the heat storage material. In this case, as described with reference to FIG. 2, the amount of heat exchange with the heat medium has decreased with the passage of time during the heat storage operation. According to the present invention, the latent heat storage material used in the heat storage unit is always in a supercooled state even in a heat radiating state and maintains fluidity, and even when supercooling is released and a solid phase precipitates, fluidity is maintained. Since the latent heat storage material circulates between the heat source unit and the heat storage unit, the latent heat storage material on the low temperature side of the latent heat storage material that is temperature-stratified by the heat storage unit is used. The latent heat storage material is supplied to the heat source unit, and when the heat storage unit radiates heat, the latent heat storage material circulates between the heat storage unit and the hot water supply unit. Thus, heat storage and heat dissipation can be performed by supplying the latent heat storage material on the high temperature side to the hot water supply unit.

  That is, at the time of heat storage, even if a part of the latent heat storage material becomes high temperature, since the latent heat storage material is stratified by temperature, it can be distinguished into a high temperature portion and a low temperature portion, When continuing the heat storage, only the heat storage material that is still in the low temperature state is supplied to the heat source unit, not the heat storage material that has become hot, and heat exchange with the heat medium is performed. Heat exchange with the latent heat storage material is performed, and as a result, the heat exchange amount does not decrease.

  Moreover, when applying a heat pump unit as a heat source unit, since the refrigerant | coolant of a heat pump has fluidity | liquidity, it is not impossible to function as a heat medium for conveying heat. However, the circulation of the refrigerant itself to the heat storage unit is not generally performed because of high-pressure refrigerant piping costs and refrigerant leakage problems. When the latent heat storage material is applied to the heat storage unit, a heat medium is mediated between the heat storage material and the refrigerant and heat is exchanged through the heat medium as disclosed in the prior art. However, in the present invention, the latent heat storage material itself is circulated to the heat pump unit, which is a heat source unit, so that no intermediate heat medium is required and the heat exchange efficiency is improved. At this time, the latent heat storage material and the refrigerant exchange heat with an alternating current type.

  Furthermore, according to the present invention, at the time of heat dissipation, contrary to the heat storage, the hot water storage material can be supplied to the hot water supply unit to exchange heat with water to generate hot water. At this time, heat is exchanged between the heat storage material and water in a counterflow type.

  During heat storage operation and heat dissipation operation, the temperature difference between the heat storage material and water required for heat exchange can be reduced by exchanging heat in the counterflow type in the heat source side heat exchanger and hot water supply heat exchanger, respectively. It becomes possible to improve the efficiency of exchange. That is, as described above, conventionally, the heat medium discharge temperature To is at least dT1 + dT2 higher than the feed water temperature Ti, that is, To−Ti ≧ dT1 + dT2. In the present invention, the temperature difference between To and Ti (To -Ti) can be remarkably reduced as compared with the prior art.

  Here, in the present invention, as described above, the tap water supplied from the other side is simply supplied to the hot water supply unit by supplying the heat storage agent having a high temperature until a predetermined time has elapsed from the start of heat dissipation. And the heat storage material perform heat exchange to generate hot water (this stage may be referred to as a “first heat radiation stage”). The heat storage material cooled by exchanging heat with tap water or the like circulates back into the heat storage unit. Here, the heat storage material used in the present invention is in a supercooled state (that is, still in a liquid state at a temperature below the freezing point). In many cases, when water or other substances undergo a phase change from a liquid phase to a solid phase, a subcooling phenomenon is exhibited to some extent. In particular, in the case of inorganic salts, supercooling is likely to occur, and many exhibit a degree of supercooling of several tens of degrees Celsius. The supercooling phenomenon is considered to be a demerit for the heat storage system, and it is common to select an operation method or a heat storage material that is avoided as much as possible. However, in the present invention, the supercooling phenomenon is actively caused and utilized.

  In the heat storage tank, the low-temperature liquid-phase heat storage material that has been cooled by the hot water supply unit and turned into a supercooled state is returned to the bottom of the tank, but at a higher density than the heat storage material (high temperature) that exists in the tank. Therefore, temperature stratification is achieved without mixing with each other. When the ratio of the heat storage material in the supercooled state reaches a predetermined value, the supercooling release device provided in the heat storage unit is operated to release the supercooled state and solidify a part of the heat storage material (become solid) ). At that time, the latent heat of solidification of the heat storage material is released, and the temperature of the entire heat storage material can be raised to the freezing point (melting point).

  By forming a heat storage material with a composition of a eutectic system composed of a plurality of components shifted from the eutectic composition in which the eutectic is generated, the fluidity can be improved even when the solid phase is precipitated by releasing the supercooling. It can be maintained. The heat storage material having the fluidity and having risen in temperature to the freezing point is supplied again to the hot water supply unit to exchange heat with tap water or the like (this stage may be referred to as a “second heat radiation stage”).

  Thus, according to the present invention, the heat storage material whose temperature has been lowered to the supercooled state in the first heat radiation stage can be used again for heat exchange by releasing the supercooling with the supercooling release device.

  Further, in the present invention, the heat source unit is a heat pump unit that uses carbon dioxide as a refrigerant and includes a heat source side heat exchanger, an expansion valve, an evaporator, and a compressor. The above-mentioned effects can be fully exhibited.

  Moreover, according to the heat storage and heat dissipation method of the present invention, the same effect as the heat storage unit in the hot water supply apparatus of the present invention can be obtained.

  Below, the hot water supply apparatus of this invention is demonstrated concretely using drawing. In addition, about the thermal storage heat dissipation method of this invention, since the thermal storage unit in the following hot water supply apparatuses is implementing the said method, the overlapping description is abbreviate | omitted.

  FIG. 3 is a configuration diagram of the hot water supply device 20 of the present invention, and shows the state of the hot water supply device during the heat storage operation.

  As shown in FIG. 3, the hot water supply device 20 of the present invention includes a heat source unit 21, a heat storage unit 22 that can store and dissipate heat from the heat source unit 21, and hot water using heat stored in the heat storage unit. And a hot water supply unit 23.

  The heat source unit 21 is particularly limited as long as the heat source unit 21 exchanges heat with the latent heat storage material used in the heat storage unit 22 and generates a quantity of heat that can raise the temperature of the latent heat storage material to a sufficient temperature. However, the present invention can be applied appropriately and used in the hot water supply apparatus of the present invention. Specifically, in addition to the heat pump unit, various internal combustion / external combustion engines (engines), fuel cells, and the like can be given. In these heat source units 21, it is needless to say that heat higher than the temperature to store heat (for example, 85 ° C.) can be supplied and sufficient heat output can be obtained. Sufficient heat output, for example, when storing heat during the night, is a heat output that can fully store the heat storage amount required for a predetermined heat storage time (for example, 8 hours from 10:00 to 6:00 the next morning). is there.

  As shown in FIG. 3, in the hot water supply apparatus 20 of the present invention, carbon dioxide is used as a refrigerant, and heat source side heat exchanger 24, expansion valve 25, evaporator 26, compression are used as main components. The heat source unit 21 composed of the machine 27 can also be used. The heat source unit 21 is a heat pump unit using carbon dioxide as a refrigerant, and is currently widely used in ordinary households.

  In the heat source unit 21, the heat source side heat exchanger 24 to the compressor 27 are arranged in this order as main components, and these are connected by piping. And it is comprised so that the carbon dioxide as a refrigerant | coolant may circulate in the said piping and each apparatus.

  First, carbon dioxide as a refrigerant is compressed by a compressor 27 that is operated by external power (such as an electric power-driven motor), and is sufficient for heat exchange with a latent heat storage material in a heat source side heat exchanger 24 described later. It becomes a high temperature and a high pressure to a certain extent (for example, 90 ° C., 9 MPa). At this time, carbon dioxide is in a supercritical state, and cannot be said to be a liquid or a gas.

  The carbon dioxide (supercritical state) that has become high temperature and high pressure by being compressed by the compressor 27 passes through the pipe, is introduced into the heat source side heat exchanger 24, and in the heat source side heat exchanger 24, the other It is cooled by exchanging heat with a low-temperature (for example, 25 ° C.) latent heat storage material introduced from. At this time, since carbon dioxide is in a supercritical state, the temperature falls without condensing even when cooled. In the heat exchanger 24, the carbon dioxide and the latent heat storage material are heat exchanged in a counterflow type.

  The heat exchange with the latent heat storage material is completed, and the carbon dioxide that has become low temperature (for example, 30 ° C.) in a high pressure state is discharged from the heat source side heat exchanger 24 and depressurized while passing through the piping provided with the expansion valve 25. It becomes a gas-liquid mixed phase state below the critical pressure.

  The carbon dioxide in a gas-liquid mixed phase state is further introduced into the evaporator 26 through a pipe. The evaporator 26 is a kind of heat exchanger, and heat exchange is performed between carbon dioxide and air to heat and carbonize the carbon dioxide. The gasified carbon dioxide passes through the pipe again and is compressed by the compressor 27 described above.

  FIG. 4 is a Mollier diagram (ph diagram) of carbon dioxide as a refrigerant circulating in the heat source unit 21.

The trapezoid shown in the figure is a heat pump cycle. A → B is compression in the compressor 27, B → C is cooling in the heat source side heat exchanger 24, C → D is expansion in the expansion valve 25, and D → A is evaporation in the evaporator 26. It can be seen that the high pressure side is in a supercritical state. The heat output as a heat pump corresponds to the length of line segments 3 and 2. The input energy corresponds to the length of line segments 1 and 2. Therefore, the efficiency (COP) as a heat pump is
COP = (line segment 3-2) / (line segment 1-2)
It is expressed by

  Here, when the cooling in the heat source side heat exchanger is not sufficient, the heat source side heat exchanger outlet temperature becomes high, and the position of C shifts to the right side in the figure. In the case of carbon dioxide refrigerant, since the refrigerant in the heat source side heat exchanger is in a supercritical state, the shift amount becomes large. For example, in the case where the temperature is only cooled to 50 ° C., the shift is made to the intersection E between the line segments B to C and the 50 ° C. isotherm. As a result, the heat output as a heat pump is reduced to the length of the line segment 4 to 2, but since the amount of input energy is not changed, the COP is greatly reduced.

  In addition, in the heat source unit 21 having such a configuration, it is normal to operate with nighttime power for the purpose of reducing operating costs.

  Next, the heat storage unit 22 which comprises the hot water supply apparatus 20 of this invention is demonstrated.

  The heat storage unit 22 is a unit for storing heat generated by the heat source unit 21 described above and dissipating it as necessary. More specifically, as described above, the heat source unit 21 is normally operated at night. On the other hand, since it is during the day that hot water generated using the heat is actually used, heat generated at night is stored until the day it is used, and heat is released during the day. Is a unit for realizing this.

  As shown in the figure, such a heat storage unit 22 can be constituted by a heat storage tank 28, a latent heat storage material filled therein, a heat storage pump 30, a heat dissipation pump 31, various pipes, and the like. The heat storage pump 30 is a pump for circulating the latent heat storage material between the heat storage unit and the heat source unit during the heat storage operation, and the heat dissipation pump 31 is a pump for circulating the latent heat storage material between the heat storage unit and the hot water supply unit during the heat dissipation operation. is there. Note that the heat storage pump and the heat dissipation pump may not be included in the heat storage unit but may be configured separately.

  Here, the feature of the present invention is that it is in a supercooled state during the heat dissipation operation (heat dissipating state) and maintains the liquid phase state, and even when the supercooling is released and the solid phase is precipitated, the fluidity can be maintained. In addition, a latent heat storage material capable of temperature stratification is used.

  Therefore, as shown in the drawing, the latent heat storage material filled in the heat storage tank 28 is stratified and filled according to its temperature (normally, the high temperature latent heat storage material is the upper layer, the low temperature latent heat storage material is filled). The material is the lower layer).

  That is, at the time of heat storage, the latent heat storage material in a low temperature state (for example, 25 ° C.) is discharged from the pipe H1 connected to the lower end of the heat storage tank 28. The latent heat storage material in a low temperature state is a supercooled liquid phase when heat is released to the first heat release stage in a heat release operation described later, and a solid-liquid mixed phase (slurry) when heat is released to the second heat release stage. The discharged low-temperature latent heat storage material is introduced into the heat source side heat exchanger 24 of the heat source unit 21 through the pipe H1 by the heat storage pump, and exchanges heat with the refrigerant (carbon dioxide) introduced from the other side. At this time, as described above, heat exchange is performed in a counterflow type. The latent heat storage material heated by heat exchange with the refrigerant and brought to a high temperature state (for example, 85 ° C.) is introduced into the heat storage tank 28 from the upper end side by the pipe H2. Since the introduced latent heat storage material has the property of temperature stratification, it hardly mixes with the low-temperature latent heat storage material in the lower layer.

  According to such a hot water supply apparatus of the present invention, even when both the high-temperature latent heat storage material and the low-temperature latent heat storage material are present inside the heat storage tank 28, the low-temperature latent heat storage material is always provided. Since only the heat source side heat exchanger 24 is supplied, the refrigerant (carbon dioxide) is always sufficiently cooled. As in the prior art, there is no problem that the outlet temperature of the heat medium that has exchanged heat with the latent heat storage material rises and the refrigerant cooled by the heat medium is insufficiently cooled.

  FIG. 5 is a configuration diagram of the hot water supply device 20 of the present invention similar to FIG. 3, and shows the state of the hot water supply device during the heat dissipation operation (first heat dissipation stage).

  In the apparatus of the present invention, when heat is released, that is, when hot water is generated using the heat stored in the latent heat storage material, a high-temperature state (for example, 85 ° C.) is connected from the pipe H2 connected to the upper end of the heat storage tank 28. ) Latent heat storage material is taken out and introduced into a hot water supply heat exchanger 29 of a hot water supply unit 23, which will be described later, by a heat dissipation pump, and heat exchange is performed with water introduced from the other side. Also in this case, the latent heat storage material and water exchange heat in a counterflow type. The latent heat storage material used in the present invention is characterized by being in a supercooled state. Therefore, the latent heat storage material cooled by heat exchange with water is still at a temperature below the freezing point (for example, 25 ° C.), but still While maintaining the liquid phase state, it is introduced into the heat storage tank 28 from the lower end side by the pipe H1. In this case, the latent heat storage material is temperature-stratified because the specific gravity is higher in the low temperature (below the freezing point) state than in the high temperature (for example, 85 ° C.) state, and the latent heat storage material in the upper layer and the lower end The low-temperature latent heat storage material introduced from the side hardly mixes. This stage is the first heat radiation stage described above.

  FIG. 6 is a configuration diagram of the hot water supply apparatus 20 of the present invention similar to FIGS. 3 and 5 and shows the state of the hot water supply apparatus during the heat dissipation operation (second heat dissipation stage).

  If the heat radiation operation as described with reference to FIG. 5 is continued, the ratio of the latent heat storage material in the supercooled state gradually increases from the lower end side in the heat storage tank 28. When the heat radiation operation is further continued in this state, the supercooled state, that is, the low-temperature latent heat storage material is introduced as it is into the hot water supply heat exchanger 29 of the hot water supply unit 23, and hot water can be produced efficiently. In addition to being unable to do so, in the unlikely event that the supercooled state is released in the hot water supply heat exchanger 29 of the hot water supply unit 23, a large amount of solid phase precipitates in the heat exchanger at one time, and the heat transfer surface of the heat exchanger Since it adheres to the surface, problems such as blockage may occur. In the present invention, when the supercooled latent heat storage material in the heat storage tank reaches a predetermined ratio, the supercool release device 28b provided in the latent heat storage material tank 28 is operated to operate the latent heat storage material tank 28. Thus, it is possible to release the supercooling in advance and change the latent heat storage material to a certain amount of solid, and to raise the temperature of the latent heat storage material to the freezing point (for example, 80 ° C.). Furthermore, the latent heat storage material of the present invention is characterized by maintaining fluidity even when supercooling is released and a solid phase is deposited. In general, the solid phase and the liquid phase have different specific gravity. Usually, since the precipitated solid phase has a specific gravity greater than that of the liquid phase, it settles in the lower part of the heat storage tank, and a supernatant liquid (latent heat storage material) having a relatively low solid fraction is present in the upper part of the heat storage tank. The supernatant liquid (latent heat storage material) of this freezing point temperature is again taken out from the pipe H2 connected to the upper end of the heat storage tank 28, introduced into the hot water supply heat exchanger 29 of the hot water supply unit 23, which will be described later, and introduced from the other. Heat exchange with water. Also in this case, the supernatant liquid (latent heat storage material) and water exchange heat with a counterflow type. Usually, since a small amount of solid phase exists in the supernatant, the solid phase acts as a supercooling release material, and the latent heat storage material cooled in the hot water supply heat exchanger 29 is in a solid-liquid mixed phase state. The supernatant liquid is the liquid phase part after the supercooling liquid in the first heat release stage is once released from the supercooling in the heat storage tank and the solid phase is deposited. The ratio of components that can be precipitated as a phase is low. Therefore, compared with the case where the supercooled liquid in the first heat dissipation stage is released as it is in the hot water supply heat exchanger 29, the solid phase fraction in the hot water supply heat exchanger 29 can be remarkably reduced. Such a problem does not occur, and the heat radiation operation can be continued smoothly. The solid-liquid mixed phase latent heat storage material cooled in the hot water supply heat exchanger 29 is introduced into the heat storage tank 28 from the lower end thereof by the pipe H1. Even in this case, the high-temperature supernatant liquid present in the upper part of the heat storage tank 28 is hardly mixed by temperature stratification. This stage is the second heat radiation stage described above.

  Here, the latent heat storage material, for example, by forming a eutectic mixture composed of a plurality of components with a composition shifted from the eutectic composition in which the eutectic is generated, is released from the supercooling and the solid phase is precipitated. Even if it exists, it becomes possible to maintain fluidity.

  Here, the supercooling release device 28b used in the hot water supply apparatus of the present invention can eliminate the supercooling state by depositing solids from the device that can exhibit the above-described action, that is, the latent heat storage material in the supercooling state. There is no particular limitation as long as it can be used. In order to release the supercooling, it is only necessary to provide an opportunity for the solid (crystal) to precipitate. For example, a device that applies ultrasonic vibration to the latent heat storage material, a substance that becomes the core of the crystal, for example, a separate storage A device that introduces the solid phase itself of the heat storage material into the liquid phase can be considered.

  In addition, a temperature measuring device (not shown) is provided at a predetermined height position of the latent heat storage material tank 28 separately from the device 28b, and the latent heat storage material is supercooled from the temperature measured by the temperature measurement device. When it is determined whether or not it is in a supercooled state, the device 28b may be automatically operated.

  FIG. 7 is a state diagram for explaining the composition change of the latent heat storage material in the first heat radiation stage and the second heat radiation stage in the hot water supply apparatus of the present invention described in FIGS.

  The two components a and b constituting the latent heat storage material used in the present invention are mixed in a liquid phase and separated into two solid phases that do not mix in the solid phase, and both are crystallized. When the eutectic composition is set to the eutectic point, the eutectic point at which the melting point becomes the minimum value causes a eutectic reaction in which the entire solution simultaneously changes to the solid phase as if it were a pure liquid. It has the characteristic that the temperature is kept constant until it changes.

That is, in the state diagram shown in FIG. 7, the liquidus line A in the figure shows the crystallization temperature (solidification start point) of the component a, and the liquidus line B in the figure shows the crystallization of the component b. The temperature (starting point of solidification) is shown. Moreover, the area | region of the code | symbol I in a figure is an area | region of a liquid phase state of the components a and b, and the code | symbol II is an area | region of the mixed state of the liquid phase (component a + component b) and the solid phase of the component a. Symbol III is a region in the mixed state of the liquid phase (component a + component b) and the solid phase of component b, and the region of symbol IV indicates a region in the solid phase state for both components a and b. The symbol X in the figure the eutectic point, X ₀ represents the eutectic composition.

The latent heat storage material used in the hot water supply apparatus and the heat storage / dissipation method of the present invention is, for example, a composition shifted from the eutectic composition in which the eutectic point X occurs in the latent heat storage material having a state diagram as shown in FIG. ₁ ), it is possible to satisfy the above-described conditions (conditions that fluidity can always be maintained even during heat radiation operation).

In the latent heat storage material having a X ₁ composition deviated from eutectic composition X _0, by tap water and heat is exchanged in the first heat radiation step, gradually decreases the temperature from the temperature T ₁ of the FIG. 7 Go. From the temperature T ₁ to T ₂ , it is in a liquid phase state (region I), and when the temperature reaches T ₂ , the component b starts to crystallize if used originally, but is used in the present invention. In the latent heat storage material, a supercooling phenomenon occurs, so that the component b is not yet deposited and remains in the liquid phase, and the component a also remains in the liquid phase. At this stage, the concentration of the component b in the liquid phase remains the desired concentration m1.

Here, by operating the supercooling release device provided in the heat storage material tank 28, supercooling is released and the component b in the liquid phase is precipitated as a solid phase. At this stage, the concentration of the component b in the liquid phase is lowered by the amount deposited as a solid phase (the concentration of the component b is m3), and the temperature of the liquid phase rises to the temperature of the liquidus line B (in the figure). reference of _{T 3).}

Thereafter, when the heat radiation operation is further continued, the temperature of the liquid phase and the concentration of the component b are reduced to T ₄ and m ₄ along the liquid phase line B.

When the supercooled heat storage material after completion of the first heat release stage is further cooled as it is to release the supercooling, and the state of T ₄ and m4 is set, the ratio of the solid phase to the liquid phase is: solid phase: liquid phase = α1 : Β1. As in the present invention, when supercooling is once canceled in the heat storage tank and the supernatant liquid is cooled (second heat radiation stage of the present invention), solid phase: liquid phase = α2: β2 in the state of T ₄ and m4. Therefore, the ratio of the solid phase can be reduced, and blockage due to the precipitation of a large amount of the solid phase in the hot water supply heat exchanger 29 can be prevented.

  When the eutectic mixture is used as the latent heat storage material, it is preferable to use a mixture whose eutectic temperature is sufficiently lower than the temperature of the supplied water (for example, 20 ° C.). By selecting as such, the heat storage material can be made into a slurry shape that maintains fluidity without the entire amount of the heat storage material becoming a solid phase even during the heat dissipation operation of the heat storage material (heat dissipation state (for example, 25 ° C.)). Become.

  As the latent heat storage material used in the apparatus and method of the present invention, any latent heat storage material can be used as long as the latent heat storage material has the above-described characteristics. For example, an ammonium alum-water mixture, an erythritol-water mixture, and the like can be preferably used.

  Furthermore, even in a mixture composed of a plurality of components that are not eutectic, the latent heat storage used in the hot water supply apparatus of the present invention is used in the state surrounded by the liquidus and solidus on the state diagram. It can be applied as a material.

  If the solid phase settles or floats due to the difference in specific gravity between the solid phase and the liquid phase and the solid phase distribution is biased in the vertical direction, the viscosity of the solid phase is increased by adding a known thickener or the like to increase the viscosity. By uniformly dispersing, a temperature stratified state can be obtained more reliably.

It is the schematic which shows the structure of a part of hot water supply apparatus using the conventional latent heat storage material. It is a schematic diagram for demonstrating the problem of a prior art intelligibly. It is a block diagram (at the time of a thermal storage driving | operation) of the hot water supply apparatus of this invention. It is a Mollier diagram of carbon dioxide as a refrigerant. It is a block diagram (at the time of a 1st heat radiation operation) of the hot water supply apparatus of this invention. It is a block diagram (at the time of a 2nd heat dissipation driving | operation) of the hot water supply apparatus of this invention. It is a state figure of the latent heat storage material used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Hot water supply apparatus 21 ... Heat source unit 22 ... Heat storage unit 23 ... Hot water supply unit 24 ... Heat source side heat exchanger 25 ... Expansion valve 26 ... Evaporator 27 ... Compressor 28 ... Heat storage tank 28b ... Supercooling release device 29 ... Hot water supply heat exchange Heat exchanger 30 ... Thermal storage pump 31 ... Radiation pump 100 ... Thermal storage material 101 ... Thermal storage tank 102 ... Heat exchanger 103 ... Heat source unit

Claims (4)

A heat source unit;
A heat storage unit capable of storing and releasing heat of the heat source unit; and
A hot water supply unit for making hot water using heat stored in the heat storage unit;
With
The heat storage unit is in a subcooled state during heat radiation operation and maintains a liquid phase state. Further, even when supercooling is released and a solid phase is deposited, the heat storage unit can maintain fluidity and can be stratified in temperature. Materials are used,
And when the latent heat storage material is in a supercooled state, the heat storage unit is provided with a supercooling release device for canceling the supercooled state,
When storing heat in the heat storage unit, the latent heat storage material circulates between the heat source unit and the heat storage unit, and at this time, the latent heat storage material on the low temperature side in the latent heat storage material stratified by the heat storage unit is used as the heat source unit. To supply and
On the other hand, when radiating heat from the heat storage unit, the latent heat storage material circulates between the heat storage unit and the hot water supply unit, and at that time, the latent heat storage material on the high temperature side in the latent heat storage material stratified by the heat storage unit is used. To the hot water supply unit,
And, it is possible to release the supercooled state by operating the supercooling release device for the latent heat storage material in the supercooled state present in the heat storage unit.
A water heater characterized by that. The hot water supply device according to claim 1,
The hot water storage device is characterized in that the latent heat storage material is formed by shifting a eutectic mixture composed of a plurality of components from a eutectic composition in which a eutectic is generated. The hot water supply device according to claim 1 or 2,
The hot water supply device, wherein the heat source unit is a heat pump unit that uses carbon dioxide as a refrigerant and includes a heat source side heat exchanger, an expansion valve, an evaporator, and a compressor. A heat storage and heat dissipation method using a latent heat storage material that maintains superfluidity and maintains a liquid phase during heat dissipation, and can maintain fluidity even when the supercooling is released and a solid phase precipitates, and is capable of temperature stratification. Because
In the heat storage stage, heat from the heat source is stored in the latent heat storage material,
In the heat release stage, the stage is divided into a first heat release stage and a second heat release stage,
In the first heat release stage, the latent heat storage material is supercooled,
Next, the latent heat storage material in the supercooled state is intentionally released from the supercooling at the stage where the first heat release stage is almost completed,
Next, in the second heat radiation stage, the latent heat storage material released from the supercooling is further radiated,
A heat storage and heat dissipation method characterized by that.

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