JP2000304479A - Thermal storage system - Google Patents

Abstract

(57) [Summary] A heat storage density suitable for the concentration of a microcapsule slurry can be obtained, and the life of the slurry can be kept long. A slurry (11) that acts as a heat storage material and has a weight concentration of 40 to 53% of a microcapsule enclosing a core material containing a latent heat storage material as a main component, and the slurry (11).
, A centrifugal pump 6 for circulating the slurry 11 in the heat storage tank 1, and heat exchange between the slurry 11 circulated by the centrifugal pump 6 and the heat utilization medium. And a heat exchanger 2 for performing the following.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applied to, for example, a heat storage facility for air conditioning, a heat storage facility for a district cooling / heating facility, a heat storage facility for an intake cooling device of a gas turbine power generation facility, an industrial heat source facility, etc., and encapsulates a latent heat storage material. The present invention relates to a heat storage system using the obtained microcapsule slurry.

[0002]

2. Description of the Related Art As a heat storage method in a conventional latent heat storage system, for example, an ice heat storage method using water as a heat storage material and utilizing the latent heat of melting and solidification of the water is known. In this method, cold water is stored as ice by cooling water using brine (antifreeze) cooled to 0 ° C. or less during heat storage, and the ice is directly cooled using heat or indirectly through brine during heat radiation. Is melted and the cold heat is taken out.

In the latent heat storage system using the conventional ice heat storage method, when storing heat, brine is cooled to -5.degree.
Therefore, it is necessary to lower the refrigerant evaporation temperature of the refrigerator, and the ratio of the amount of heat storage to the input of the refrigerator, that is, the coefficient of performance, becomes lower. In addition, it is necessary to use brine when cooling ice, and care must be taken in its management.

As another example of a latent heat storage system, a latent heat storage material that changes phase at room temperature is utilized, and the latent heat storage material is encapsulated in a capsule or container as a core material to form cold water or water. Cooling as a solid by cooling using brine, or storing heat as a liquid by heating using warm water, and indirectly melting the cold heat by indirectly melting the latent heat storage material during heat radiation, taking out the heat by solidifying Methods are known. When using the latent heat storage material that changes phase at normal temperature, it is necessary to enclose the latent heat storage material in a capsule or container in terms of handling when the latent heat storage material has volatility or when used in a eutectic salt solution. .

On the other hand, as these capsules and containers, spherical ones having a diameter of 70 mm or rectangular or plate-like containers having a side of several tens cm are used, filled in a heat storage tank and used in a stationary state. The space between the heat storage tank and these capsules or containers is filled with water or brine.

[0006] In such a stationary capsule system and a container system, during heat storage and heat radiation, between these capsules or containers (hereinafter referred to as heat storage material containers) and a heat medium fluid such as water, or heat storage. The thermal resistance between the wall of the material container and the latent heat storage material is large. Therefore, the temperature of the latent heat storage material heated at the time of heat release or the temperature difference between the temperature of the latent heat storage material cooled at the time of heat storage and the temperature of the heat medium fluid used, such as water, must be about 5 ° C. or more in each state. The temperature of the heat transfer fluid used such as water during heat storage and heat release is 10
It is necessary to provide a temperature difference of at least ° C. That is, when trying to extract cold water of 5 ° C., it is necessary to cool with brine of −5 ° C. when storing heat. In addition, if it is attempted to store heat at a temperature level where brine is not used, the cold water discharge temperature will be 1
The temperature is 0 ° C. or higher, which is a temperature that cannot be directly used for general air conditioning and the like.

In order to solve the problem of the system using such a latent heat storage method, a microcapsule formed by encapsulating a latent heat storage material as a core material in a microcapsule is mixed with water to form a slurry to form a fluid. (Below,
This slurry is referred to as a microcapsule slurry), and a system with improved heat transfer performance is known. In this system, at the time of heat storage, the microcapsule slurry is cooled by exchanging heat with cold water or brine by a heat exchanger to cool the latent heat storage material in the microcapsules. Further, at the time of heat radiation, the microcapsule slurry is similarly returned by a heat exchanger and heated by exchanging heat with cold water or brine, thereby extracting cold heat from the latent heat storage material in the microcapsules.

[0008] In such a microcapsule slurry system, the microcapsules themselves flow and exchange heat with the heat transfer fluid through the heat transfer surface, which is sufficiently higher than the above-mentioned stationary heat storage material container system. The heat transfer coefficient is obtained, and the heat storage / radiation temperature close to the value of a general fluid such as water and close to the melting point and freezing point of the latent heat storage material (the temperature difference between the microcapsule slurry and the fluid used such as water is 0.75 C. to about 3 C.).

[0009]

In the above-mentioned microcapsule slurry method, when the concentration of the microcapsules is lowered to obtain fluidity, the ratio of the latent heat storage material in the slurry becomes small, and the amount of heat that can be stored by the heat storage material, that is, the heat storage The density will be smaller. This concentration is usually less than 40%. Therefore, in order to increase the amount of heat stored in the heat storage material, it is necessary to use a highly concentrated microcapsule slurry.

On the other hand, when a microcapsule slurry having a concentration of about 40 to 53% is used, since the slurry has a high viscosity, it is conceivable to use a gear-type or other positive displacement pump in the slurry circulation circuit. However, when a positive displacement pump such as a gear pump is used, the microcapsule slurry sucked into the positive displacement pump such as a gear pump is slid and discharged by gears or the like. Its life is shortened. Therefore, it is necessary to use a pump having no sliding function.

When a microcapsule slurry having a concentration of about 53 to 60% is used, the viscosity increases with an increase in the concentration, so that the pipe resistance increases and the pump efficiency decreases. Problem.

When a microcapsule slurry having a concentration of about 60% or more is used, the slurry becomes gel-like as the concentration increases, and there is a problem that the slurry cannot be circulated in the slurry circulation circuit even with a pump.

An object of the present invention is to provide a heat storage system capable of obtaining a heat storage density suitable for the concentration of the microcapsule slurry and keeping the life of the slurry long.

[0014]

Means for Solving the Problems To solve the above problems and achieve the object, a heat storage system of the present invention is configured as follows.

(1) The heat storage system of the present invention is a slurry that acts as a heat storage material and has a weight concentration of 40 to 53% of a microcapsule in which a core material containing a latent heat storage material as a main component is encapsulated, and this slurry is used. A heat storage tank for storing, a centrifugal pump for circulating the slurry in the heat storage tank, and a heat exchanger for performing heat exchange between the slurry and a heat utilization medium circulated by the centrifugal pump, It is composed of

(2) The heat storage system of the present invention has a slurry in which a microcapsule, which acts as a heat storage material and encapsulates a core material containing a latent heat storage material as a main component, has a weight concentration of 53 to 60%, and A heat storage tank for storing, a spiral pump for circulating the slurry in the heat storage tank, and heat exchange between the slurry and a heat utilization medium attached to the heat storage tank and circulated by the spiral pump. And a heat exchanger for performing the heat treatment.

(3) The heat storage system according to the present invention stores a slurry in which the weight concentration of the microcapsules enclosing a core material containing a latent heat storage material as a main component and acting as a heat storage material is 60% or more, and this slurry. A heat storage tank, and a heat exchanger installed in the heat storage tank, including a pipe, and performing heat exchange between the slurry and a heat utilization medium passing through the pipe.
It is composed of

(4) The heat storage system of the present invention has the above (1)
Or, the system according to (2), wherein the heat exchanger is an inner plate fin type of a compact heat exchanger, and the temperature of the heat storage material and the temperature of the used chilled water are substantially equal.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a diagram showing a configuration of a heat storage system according to a first embodiment of the present invention. This heat storage system is applied to district cooling and heating, and as shown in FIG. 1, a heat storage tank (latent heat storage tank) 1,
It comprises a heat exchanger 2, a slurry circulation circuit 3, a cold water circulation circuit 4, a refrigerator 5, and the like.

The heat storage tank 1 is a container containing a microcapsule slurry 11 in which a myriad of microcapsules are mixed with water at a predetermined concentration to form a slurry. The concentration of the microcapsules in the microcapsule slurry is about 40 to 53%, and the remaining about 60 to 47% is water and some diffusing agent.
A latent heat storage material that changes its phase at room temperature and stores latent heat is encapsulated as a core material in each microcapsule.

As the latent heat storage material, tetradecane (T) which is an aliphatic hydrocarbon (paraffinic hydrocarbon) is used.
A mixture of D) and pentadecane (PD) is used, and a melamine resin (organic resin) is used as a film of the microcapsules. The particle size of one microcapsule is preferably 1 to
Although it is about 2 μm, it is practical if it is about 20 μm or less.

A heat exchanger (compact heat exchanger) 2 is connected to the heat storage tank 1 via a slurry circulation circuit 3 having a slurry pump 6. Furthermore, in the heat exchanger 2,
Refrigerator 5 via chilled water circulation circuit 4 equipped with chilled water pump 8
The evaporator 51 inside is connected.

Therefore, during heat storage and heat release, the slurry pump 6 is operated to supply the microcapsule slurry 11 in the heat storage tank 1 to the heat exchanger 2 through the slurry circulation circuit 3. The chilled water pump 7 or the chilled water pump 8 is operated to supply chilled water to the heat exchanger 2 through the chilled water circulation circuit 4. Thereby, heat exchange can be performed between the microcapsule slurry 11 and the cold water in the heat exchanger 2.

For example, during nighttime heat storage, the microcapsule slurry 11 sucked from the heat storage tank 1 is transferred to the heat exchanger 2.
In the above, it is cooled to 4.25 ° C. by exchanging heat with 3.5 ° C. cold water cooled by a refrigerator, and stores the cold heat when the latent heat storage material of each microcapsule changes to a solid phase,
It is returned to the heat storage tank 1. By continuing this circulation,
In the heat storage tank 1, the latent heat storage material of each microcapsule is replaced with a microcapsule slurry at 4.25 ° C. which has changed to a solid phase, and the heat storage is completed.

At the time of heat release in the daytime, the slurry circulation circuit 3 is switched, and the microcapsule slurry 11 at 4.25 ° C. in which each of the microcapsule latent heat storage materials has changed to a solid phase is supplied to the heat exchanger 2. In the heat exchanger 2, the chilled water circulation circuit 4 is switched so that the returned chilled water of 12 ° C. from the load side and 4.25
The microcapsule slurry is heat-exchanged with the microcapsule slurry to give cold water to the cold water when the latent heat storage material of each microcapsule changes to a liquid phase. This cold water is supplied to the load side as 5 ° C. feed cold water. The microcapsule slurry 11 in which the latent heat storage material of each microcapsule has changed phase is heated to 11.25 ° C.
It is returned to the latent heat tank 1.

The refrigerator 5 is operated by using inexpensive electric power at night, and cool water generated by the evaporator 51 is supplied to the heat exchanger 2.
Supply to The heat taken by the evaporator 51 is transferred to the compressor 5
2 and from the cooling tower 9 via the condenser 53.

According to the first embodiment, 40 to 53
% Of the microcapsule slurry,
About 14-17Mc suitable for microcapsule slurry concentration
A heat storage density of al / m ³ is obtained. Further, since the centrifugal pump 6 is used without using a positive displacement pump as the slurry pump, the slurry does not slide in the pump, the life of the slurry is prolonged, and the apparatus can be configured at low cost.

(Second Embodiment) A heat storage system according to a second embodiment of the present invention has a concentration of microcapsules in a microcapsule slurry of about 53 to 60% (the remaining about 47 to 40% is water). And a small amount of a diffusing agent), so that the concentration is about 17 to 2 which is suitable for the concentration of the microcapsule slurry.
A heat storage density of 0 Mcal / m ³ is obtained.

In this heat storage system, in the configuration shown in FIG. 1, the heat exchanger 2 is a compact heat-transfer surface shape and flow path cross-sectional area suitable for the characteristics of the microcapsule slurry and the chilled water. By using a plate fin type heat exchanger which is a heat exchanger, the heat exchanger 2 is mounted on the side surface of the heat storage tank 1 and the like, and the piping of the slurry circulation circuit 3 is reduced, thereby suppressing the pump power. Further, the viscosity of the slurry is increased as compared with the first embodiment, and it is difficult to use a centrifugal pump having a small suction force in the slurry pump 6, and a spiral pump which is a positive displacement pump is used instead.

FIG. 2 is a diagram showing the configuration of the spiral pump. In this pump, a transfer pipe 22
The microcapsule slurry sucked into the inside is spirally transferred toward a discharge port 25 by a transfer shaft 24 rotated by a motor 23. From the discharge port 25, the spiral slurry is discharged to the pipe 26. In this pump, since there are few sliding portions of the slurry as in the case of a gear-type positive displacement pump, the life of the slurry can be kept long.

(Third Embodiment) FIG. 3 is a diagram showing a configuration of a heat storage system according to a third embodiment of the present invention. In FIG. 3, the same portions as those in FIG. 1 are denoted by the same reference numerals, and the detailed description of the overlapping portions will be omitted.

In the heat storage system according to the third embodiment, the concentration of the microcapsules with respect to the microcapsule slurry is about 60% or more (preferably 65%, and the remaining 40% or less is water and some diffusing agent). About 20 Mcal / m ³ , adapted to the concentration of the microcapsule slurry.
Is obtained. However, the slurry becomes gel-like, and it is difficult to circulate the slurry in the slurry circulation circuit even with a pump.

As shown in FIG. 3, in the present heat storage system, the heat exchanger 2 shown in FIG.
An external fusion type heat transfer section 31 is provided in the slurry 11.
The heat transfer tube 32 of the heat transfer unit 31 constitutes a heat exchanger including a heat transfer coil, a plate fin tube, a heat transfer coil, and the like. Both ends of the heat transfer tube 32 are connected to a cold water circulation circuit 4 having a cold water pump 33. It is connected.

Cold water circulating in the cold water circulation circuit 4 flows in the heat transfer tube 32, and the slurry 11 in the heat storage tank 1 generates natural convection and exchanges heat with the cold water in the heat transfer tube 32. Since heat exchange is performed in the heat storage tank 1 by such a configuration, it is not necessary to transport the gel-like slurry, so that the life of the slurry can be kept long, and the centrifugal pump serving as the slurry transport power as shown in FIG. 6 and a positive displacement pump are not required, and heat storage and heat dissipation can be performed in the gel-like microcapsule slurry.

(Fourth Embodiment) In the first and second embodiments, a compact heat exchanger is used as the heat exchanger 2 corresponding to a high-viscosity slurry, so that the installation space can be reduced. And can increase the economy. As this compact heat exchanger, a plate heat exchanger, a plate fin heat exchanger, a spiral heat exchanger and the like can be used.

In particular, a plate fin type heat exchanger in which the shape of the heat transfer surface and the cross-sectional area of the flow passage are easily adjusted to the characteristics of the fluids on the side of the microcapsule slurry and the cold water, respectively, is desirable.

FIG. 4 shows a compact heat exchanger.
Logarithmic mean temperature of tofin and plate heat exchangers
An example of the relationship between the difference and the heat transfer area is shown. According to this example,
The average heat transfer coefficient of the top fin heat exchanger is about 100 on average.
0 kcal / m^Two h ° C, plate heat
The overall heat transfer coefficient of the exchanger is about 500 kcal / m on average ^Two
h ° C., which is about half that of the plate fin type. Sand
In other words, when trying to obtain the same heat exchange under the same temperature conditions,
For rate fin type heat exchanger, for plate type heat exchanger
Heat transfer area is about half that of
And the economy can be improved.

On the other hand, when the plate fin type and the plate type are compared as heat exchangers having the same heat transfer area, the plate fin type can reduce the logarithmic average temperature difference to about half of the plate type, and the microcapsule slurry The difference between the heat storage temperature and the water use temperature can be reduced and made substantially equal.

The present invention is not limited to only the above embodiments, and can be implemented with appropriate modifications without departing from the scope of the invention.

(Summary of Embodiment) [1] The heat storage system according to the first embodiment has a paraffin (TD-TD) having a weight concentration of about 40 to 53% as a heat storage material.
A microcapsule slurry 11 containing a PD mixture);
It comprises a heat storage tank 1 for storing the same, a centrifugal pump 6 for circulating the slurry 11, a connection pipe, and one heat exchanger 2 for heat exchange with cold or hot water heat utilization medium as heat storage and radiation. Note that a compact heat exchanger (plate heat exchanger, plate fin heat exchanger, spiral heat exchanger) is used as the heat exchanger 2.

Thus, the slurry 1 in the centrifugal pump 6
1 is not slid, the life of the slurry 11 is lengthened, and the apparatus can be configured at low cost. Furthermore, by adopting a compact heat exchanger as the heat exchanger 2 corresponding to a slurry having a high viscosity, the installation space can be reduced and the economy can be improved.

[2] The heat storage system according to the second embodiment comprises a microcapsule slurry 11 containing paraffin (TD-PD mixture) having a weight concentration of about 53 to 60% as a heat storage material, and a heat storage tank for storing the slurry. 1 and slurry 11
A spiral pump, which is a positive displacement pump, as a slurry pump 6 for circulating water, and a heat exchanger 2 attached to a set of heat storage tanks 1 that exchange heat with a connecting pipe and a heat utilization medium of cold water or hot water as heat storage and radiation. Have. Note that a compact heat exchanger (plate fin heat exchanger) is used as the heat exchanger 2.

Thus, the pump power is suppressed to reduce the economic constraints caused by the temperature rise, and the slurry has a small sliding portion in the pump, so that the life of the slurry can be maintained long.

[3] The heat storage system according to the third embodiment includes a microcapsule slurry 11 containing paraffin (TD-PD mixture) having a weight concentration of about 60% or more as a heat storage material, and a heat storage tank 1 for storing the slurry. A heat transfer section (heat transfer coil, plate fin tube, heat transfer coil, etc.) 31 installed in the heat storage tank 1 and acting as a heat exchanger;
The heat transfer section 31 includes a heat transfer tube 32 through which a heat utilization medium of cold water or hot water guided from outside the heat storage tank 1 flows.

As a result, heat exchange is performed in the heat storage tank 1, so that it is not necessary to transport the gel slurry, the life of the slurry can be kept long, and a centrifugal pump or a positive displacement pump serving as the slurry transport power can be used. This eliminates the need for heat storage and heat dissipation in the gel-like microcapsule slurry.

As the heat exchanger 2, a compact heat exchanger (plate heat exchanger, plate fin heat exchanger, spiral heat exchanger) is used.

[4] The heat storage system according to the fourth embodiment is the system according to the above [1] or [2], wherein the heat exchanger 2 is an inner plate fin type compact heat exchanger, The temperature of the heat storage material and the temperature of the used cold water are almost equal.

As a result, it is possible to plan an optimal heat transfer channel surface for each of the microcapsule slurry radiating cold water in the heat exchanger, to increase the overall heat transfer coefficient, to reduce the installation space, and to increase the economic efficiency. Thus, the temperature of the heat storage material and the temperature of the radiating cold water can be made substantially equal.

[0049]

According to the heat storage system of the present invention, a heat storage density suitable for the concentration of the microcapsule slurry can be obtained, the slurry does not slide in the centrifugal pump, and the life of the slurry is extended.

According to the heat storage system of the present invention, a heat storage density suitable for the concentration of the microcapsule slurry can be obtained, the pump power is suppressed, and the portion of the slurry that slides in the pump is small, so that the life of the slurry is extended. Can be kept.

According to the heat storage system of the present invention, a heat storage density suitable for the concentration of the microcapsule slurry can be obtained, and heat exchange is performed in the heat storage tank. Can be maintained for a long time, and a centrifugal pump or a positive displacement pump serving as a slurry transfer power is not required.

According to the heat storage system of the present invention, it is possible to plan optimal heat transfer passage surfaces for the microcapsule slurry side and the radiating chilled water side in the heat exchanger, thereby increasing the overall heat transfer coefficient and installing space. Can be reduced and the economic efficiency can be improved, and the temperature of the heat storage material and the temperature of the radiating cold water can be made substantially equal.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a heat storage system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a spiral pump according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a heat storage system according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a logarithmic average temperature difference and a heat transfer area of a heat exchanger according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermal storage tank 11 ... Microcapsule slurry 2 ... Heat exchanger 3 ... Slurry circulation circuit 4 ... Cold water circulation circuit 5 ... Refrigerator 51 ... Evaporator 52 ... Compressor 53 ... Condenser 6 ... Centrifugal pump 7 ... Cold water pump 8 ... Cooling water pump 9 ... Cooling tower 10 ... Cooling water pump 21 ... Piping 22 ... Transfer pipe 23 ... Motor 24 ... Transport shaft 25 ... Outlet 26 ... Piping 31 ... Heat transfer part 32 ... Heat transfer pipe 33 ... Chill water pump

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Akira Fukuda, Inventor, 24, Kinone Jindai, Narita, Chiba Prefecture Inside the New Tokyo International Airport Corporation (72) Inventor, Tadashi Tsuno 24, Kinone Jindai, Narita, Chiba, Japan (72) Inventor Toshihiro Suzuki 24, Kinone Jindai, Narita City, Chiba Prefecture New Tokyo International Airport Corporation (72) Inventor Toshio Tashiro 24, Kinone Jindai, Narita City, Chiba Prefecture New Tokyo International Airport Corporation (72) Inventor Takao Yokose 24, Kinonejidai, Narita-shi, Chiba Pref. Inside the New Tokyo International Airport Corporation (72) Inventor Seiji Shibuya 2-1-1, Aramachi-cho, Niihama, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. 2-1-1 Niihama, Arai-machi, Takasago City, Hyogo Prefecture Inside the Takasago Works, Mitsubishi Heavy Industries, Ltd. (72) Inventor Yoshinori Shirakata Niihama, Arai-machi, Takasago City, Hyogo Prefecture 2-1-1, Mitsubishi Heavy Industries, Ltd. Takasago Research Laboratory (72) Inventor Yoichiro Iriya 2-1-1, Araimachi, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Research Laboratory (72) Inventor Tadaaki Yai Takasago, Hyogo Prefecture 2-1-1, Niihama, Araimachi Inside the Takasago Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Mika Shinka 2-1-1, Niihama, Araimachi, Takasago-shi, Hyogo Prefecture Inside the Takasago Laboratory, Mitsubishi Heavy Industries, Ltd.

Claims (4)

[Claims] 1. A slurry that acts as a heat storage material and has a weight concentration of 40 to 53% of a microcapsule enclosing a core material containing a latent heat storage material as a main component, a heat storage tank for storing the slurry, A centrifugal pump for circulating the slurry in the tank; and a heat exchanger for performing heat exchange between the slurry and a heat utilization medium circulated by the centrifugal pump. Thermal storage system. 2. A slurry which acts as a heat storage material and has a weight concentration of 53 to 60% of a microcapsule enclosing a core material containing a latent heat storage material as a main component, a heat storage tank for storing the slurry, A spiral pump for circulating the slurry in a tank, and a heat exchanger attached to the heat storage tank and performing heat exchange between the slurry and a heat utilization medium circulated by the spiral pump. A heat storage system, comprising: 3. A slurry that acts as a heat storage material and has a weight concentration of 60% or more of a microcapsule enclosing a core material containing a latent heat storage material as a main component, a heat storage tank for storing the slurry, and a heat storage tank. A heat exchanger installed inside the heat exchanger and performing heat exchange between the slurry and the heat utilization medium. 4. The heat storage system according to claim 1, wherein the heat exchanger is an inner plate fin type of a compact heat exchanger, and a temperature of a heat storage material is substantially equal to a temperature of used chilled water.