JP2012002469A - Heat accumulating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine that a heat accumulating material 1 is in a supercooled sate (latent heat accumulated state).SOLUTION: The heat accumulating material 1 has a supercooling property. When the heat accumulating material 1 is heated to a temperature of its melting point or higher to turn liquefied and is cooled in its liquid state to a temperature below the melting point, latent heat is accumulated in the heat accumulating material 1. A controller 5 determines that the heat accumulating material 1 is in a supercooled state when its temperature is the melting point or lower and light transmittance is equal to or higher than a given value (equivalent to a liquid state), based on a signal from a temperature sensor 6 and a signal from an optical sensor 7 (light projector 7a and light-receiver 7b). Under at least one condition that the heat accumulating material 1 is in the supercooled state, voltage is applied to a thermoelectric element 4 serving as a nucleating unit to cause nucleation, by which latent heat is released.

Description

  The present invention relates to a heat storage device using a heat storage material having supercoolability, and more particularly to a technique for determining whether or not the heat storage material is in a supercooled state.

  A heat storage device is a device that stores heat and takes it out again, and uses a latent heat of phase transition. Specifically, as described in Patent Document 1 and Patent Document 2, a heat storage material having supercooling properties is used, and after heating this to a melting point or higher to form a liquid state, the liquid state is cooled to the melting point or lower. Latent heat is stored by natural cooling. Thereafter, activation heat is applied to the supercooled heat storage material to generate solid phase nuclei (nucleation), thereby generating latent heat (solidification heat). As the nucleation means, a thermoelectric element (Peltier element) is generally used.

Japanese Patent Publication No. 05-048799 JP 2007-285549 A

However, in the conventional heat storage device, it has not been possible to accurately know whether or not the latent heat storage material having supercoolability is actually in a supercooled state. For this reason, voltage is applied to the thermoelectric element as the nucleating means regardless of whether or not the heat is actually stored, and in some cases, electric energy is wasted.
In Patent Document 2, a temperature sensor is provided in the heat storage material, and it is determined whether or not the heat storage state is based on the temperature distribution. It is difficult to accurately determine whether or not.

  This invention makes it a subject to make it possible to discriminate | determine reliably whether a thermal storage material exists in a supercooled state (latent-heat thermal storage state) in view of such an actual condition.

  In order to solve the above problems, the present invention provides a temperature sensor for detecting the temperature of the heat storage material and an optical sensor for detecting the light transmittance of the heat storage material, and based on the signals from the temperature sensor and the optical sensor. The supercooling state is determined.

  The present invention can accurately determine the supercooled state by detecting the temperature and light transmittance of the heat storage material. That is, in the supercooled state, the temperature is lower than the melting point and the liquid state. Whether it is a solid state or a liquid state can be determined from the light transmittance (if the light transmittance is a predetermined value or more, it can be determined as a liquid state). Therefore, by using the temperature sensor and the optical sensor and detecting the temperature and the light transmittance, the supercooling state can be accurately determined from these.

  Therefore, according to the present invention, it is possible to accurately determine the supercooled state of the heat storage material and to optimize the operation of the nucleation means.

System diagram of a heat storage device showing the first embodiment of the present invention Characteristics chart of supercooling heat storage material Flow chart of supercooling determination routine Flow chart of nucleation control routine System diagram of heat storage device showing second embodiment of the present invention System diagram of heat storage device showing third embodiment of the present invention System diagram of heat storage device showing fourth embodiment of the present invention System diagram of heat storage device showing fifth embodiment of the present invention The figure which shows the example 1 of arrangement | positioning of an optical sensor (light projection part / light-receiving part) The figure which shows the example 2 of arrangement | positioning of an optical sensor (light projection part / light-receiving part) The figure which shows the example 3 of arrangement | positioning of an optical sensor (light projection part / light-receiving part) The figure which shows the example 4 of arrangement | positioning of an optical sensor (light projection part / light-receiving part) The figure which shows the example 5 of arrangement | positioning of an optical sensor (light projection part / light-receiving part) The figure which shows the example 6 of arrangement | positioning of an optical sensor (light projection part / light-receiving part)

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a system diagram of a heat storage device showing a first embodiment of the present invention.
The heat storage material 1 is a latent heat storage material having supercooling properties. For example, a hydrate salt such as sodium acetate trihydrate or sodium sulfate decahydrate, and a carrier of the hydrate salt, such as xanthan gum, guar gum, locust, etc. It consists of hydrophilic polysaccharides such as bean gum, or thickeners such as starch and polyacrylic acid, and is enclosed in a storage container.

  The supercooling heat storage material 1 has a melting point of, for example, 50 to 60 ° C., and is heated to a temperature equal to or higher than the melting point to be in a liquid state. Is done. Then, the supercooled state is released by applying a stimulus for activation (local cooling or the like) to the supercooled heat storage material 1 to generate solid phase nuclei. The latent heat stored in can be released.

The heat storage material 1 is provided with a heating circuit (heating means) 2 for heat input and a heat radiation circuit (heat radiation means) 3 for heat output so that heat exchange is possible.
The heating circuit 2 circulates a heat medium between a heat collecting heat exchanger 11 provided in thermal contact with an external heat source and a heat input heat exchanger 12 provided in the heat storage material 1. In the circulation path, a pump 13 and a flow control valve 14 are provided.

The heat radiating circuit 3 circulates a heat medium between a heat collecting heat exchanger 21 provided in the heat storage material 1 and a heat radiating heat exchanger 22 provided in a portion requiring heat. The circulation path is provided with a pump 23 and a flow rate control valve 24.
In the heat storage material 1, one to a plurality of thermoelectric elements (Peltier elements) 4 are provided as nucleation means, and the operation of the thermoelectric elements 4 is performed by an external controller 5.

In order to control nucleation by the thermoelectric element 4, a temperature sensor 6 and an optical sensor 7 are provided in the heat storage material 1, and these signals are input to the controller 5.
The temperature sensor 6 detects the temperature of the heat storage material 1 and may be any sensor that can detect at least whether the temperature of the heat storage material 1 is higher or lower than the melting point.
The optical sensor 7 detects the light transmittance of the heat storage material 1. Specifically, it is configured to include a light projecting unit 7a and a light receiving unit 7b that are opposed to each other via the heat storage material 1, and from the ratio of the amount of light received by the light receiving unit 7b to the light projection amount (constant) of the light projecting unit 7a, The light transmittance is detected. If the light projection amount is constant, the light transmittance can be detected from the level of the amount of received light.

FIG. 2 shows an example in which the relationship between the heat storage material temperature and the light transmittance is measured for the supercooling heat storage material and the non-supercooling heat storage material.
In the case of a non-supercooling heat storage material, the light transmittance is lowered by changing from a liquid state above the melting point to a solid state below the melting point.
In the case of a supercooling heat storage material, even if it is below the melting point, the liquid state is maintained due to the supercooling property, so the light transmittance is maintained high, and the solid state becomes below the supercooling limit temperature. Thus, the light beam reduction rate is reduced.

Therefore, if the light transmittance is equal to or higher than the predetermined value, it can be determined as a liquid state, and if the temperature is lower than the melting point and the light transmittance is equal to or higher than the predetermined value, it is determined as being in a supercooled state (latent heat storage state). it can. Here, the predetermined value is a threshold value set between the light transmittance in the solid state and the light transmittance in the liquid state.
Next, the operation will be described.

When heat is generated by the external heat source, heat is collected by the operation of the heating circuit 2 (pump 13), that is, by the heat collecting heat exchanger 11 provided in thermal contact with the external heat source, and is passed through the heat input heat exchanger 12. Then, the heat storage material 1 is heated to the melting point or higher. At this time, the heat storage material 1 is heated to the melting point or higher to be in a liquid state and regenerated.
After the regeneration, the operation of the heating circuit 2 is stopped, and the heat storage material 1 is cooled to the melting point or lower by natural cooling, and the supercooling state is maintained in the liquid state by utilizing the supercooling property. Thereby, latent heat is stored in the heat storage material 1.

Thereafter, when the heat stored in the heat storage material 1 is to be used, the signals of the temperature sensor 6 and the optical sensor 7 are read into the controller 5.
When the temperature of the heat storage material 1 detected by the temperature sensor 6 is lower than the melting point and the light transmittance of the heat storage material 1 detected by the optical sensor 7 is equal to or higher than a predetermined value, the controller 5 It discriminate | determines from a state (latent heat thermal storage state), and the thermoelectric element 4 as a nucleation means is operated.

FIG. 3 is a flowchart of a supercooling determination routine executed by the controller 5.
In S1, the signal of the temperature sensor 6 (the temperature of the heat storage material 1) is read. In S2, it is determined whether or not the temperature of the heat storage material 1 is lower than the melting point. If this determination is YES, the process proceeds to S3.
In S3, the signal of the optical sensor 7 (light transmittance of the heat storage material 1) is read. In S4, it is determined whether or not the light transmittance is higher than a predetermined value, that is, whether or not it is in a liquid state. If this determination is YES, the process proceeds to S5.

That is, when the temperature of the heat storage material 1 is lower than the melting point and the light transmittance is equal to or higher than the predetermined value, the process proceeds to S5, and it is determined that the liquid state is lower than the melting point, that is, the supercooled state, and the flag FS is set (FS = 1).
In contrast, when the temperature of the heat storage material 1 is equal to or higher than the melting point (NO in the determination of S2) or when the light transmittance of the heat storage material 1 is less than a predetermined value and the heat storage material 1 is in a solid state (determination of S4) If NO, the process proceeds to S6, where it is determined that the state is not the supercooling state, and the flag FS is reset (FS = 0).

FIG. 4 is a flowchart of a nucleation control routine executed by the controller 5.
In S11, it is determined whether or not there is a heat release request (a request to use heat stored in the heat storage material 1). If there is a heat release request, the process proceeds to S12.
In S12, it is determined based on the value of the flag FS whether or not the heat storage material 1 is in a supercooled state (latent heat heat storage state). When the heat storage material 1 is in a supercooled state (FS = 1), the process proceeds to S13.

In S13, the thermoelectric element 4 as a nucleation means is operated (specifically, a voltage is applied to the thermoelectric element 4). If the determination in S11 or S12 is NO, this routine is terminated without operating the nucleation means.
When the thermoelectric element 4 as the nucleation means is operated, that is, when a voltage is applied to the thermoelectric element 4, the heat storage material 1 is locally cooled and reaches the supercooling limit temperature locally, resulting in nucleation. Solidification begins. Thereby, latent heat (heat of solidification) is generated along with the phase change.

The generated latent heat is recovered by the operation of the heat radiating circuit 3 (pump 23), that is, by the heat collecting heat exchanger 21, and is supplied to the portion requiring heat through the heat radiating heat exchanger 22.
As a specific heat recovery / utilization mode, for example, in the case of an automobile, waste heat from the engine (internal combustion engine), motor, fuel cell, etc. is used as a heat source during normal operation, and heat that has been discarded in the past is used. Collect and store heat. The heat is taken out and used at a desired point in time, for example, at the time of start-up, thereby saving power and energy. Use points of heat include warming up of engines, motors, fuel cells, etc., heating of passenger compartments (including heating of seats), defrosting of windows, warming of refrigerant in the crank chamber of variable capacity compressors for air conditioning, etc. Can be mentioned.

As a nucleation means, the use of a thermoelectric element (Peltier element) 4 has advantages such as good mountability and repeated use, but in addition, an impact generating element that gives mechanical stimulation is used. You can also.
Next, another embodiment of the present invention will be described.
FIG. 5 is a system diagram of a heat storage device showing a second embodiment of the present invention.

  In the embodiment of FIG. 5, a fan 25 is provided as a heat dissipating means instead of the heat dissipating circuit 3, and when the latent heat is generated by the operation of the nucleating means, the fan 25 is operated by the controller 5 to generate heat. The warm air is blown to the part that needs to be used. Thereby, it becomes unnecessary to provide a heat radiating means in the heat storage material 1, and a structure can be simplified. Further, for the control of the blower 25, a temperature sensor 8 is provided on the heat output side of the heat storage material 1 so that it can be determined whether or not the temperature is at a level where heat can be radiated.

FIG. 6 is a system diagram of a heat storage device showing a third embodiment of the present invention.
In the embodiment of FIG. 6, the heat input heat exchanger 12 of the heating circuit 2 as the heating means is provided not in the heat storage material 1 but outside the heat storage material 1 in thermal contact. Thereby, it becomes unnecessary to provide a heating means in the heat storage material 1, and a structure can be simplified. Moreover, the internal structure of the heat storage material 1 can be greatly simplified by implementing together with the fan 25 of a heat radiating means.

FIG. 7 is a system diagram of a heat storage device showing a fourth embodiment of the present invention.
In the embodiment of FIG. 7, the heating circuit 2 as a heating means is provided in a form added to the existing heat circulation circuit 2 ′.
The existing heat circulation circuit 2 ′ is a heat medium between a heat collecting heat exchanger 11 provided in thermal contact with an external heat source and a heat output heat exchanger 15 provided in a portion requiring heat. The circulation path is provided with a pump 13 and a flow rate control valve 14. The heat output heat exchanger 15 is used as, for example, a vehicle air conditioner or an auxiliary machine heating device.

A heat input heat exchanger 12 provided in (or in thermal contact with) the heating circuit 2, specifically, the heat storage material 1 is connected to the heat circulation circuit 2 ′ via the four-way valve 16. By doing so, a heating means for the heat storage material 1 is configured.
The four-way valve 15 is switched between the state shown in FIG. A and the state shown in FIG. B by the controller 5, and in the state shown in FIG. A, the heat circulation circuit 2 ′ and the heating circuit 2 are connected in series, and in the state shown in FIG. The heat circulation circuit 2 ′ and the heating circuit 2 are disconnected.

  Accordingly, when the heat storage material 1 is heated to the melting point or higher, the controller 5 switches the four-way valve 15 to the state shown in FIG. A so that the heat collecting material is collected by the heat collecting heat exchanger 11 provided in thermal contact with the external heat source. The heated heat medium flows to the heat input heat exchanger 12 through the four-way valve 16 by the pump 13, and the heat can be given to the heat storage material 1. In other cases, the operation of the heating circuit 2 can be stopped by switching the four-way valve 15 to the state shown in FIG.

FIG. 8 is a system diagram of a heat storage device showing a fifth embodiment of the present invention.
In the embodiment of FIG. 8, a plurality of optical sensors are provided for detecting the light transmittance of the heat storage material 1. That is, apart from the optical sensor 7 (light projecting unit 7a and light receiving unit 7b), another optical sensor 7 ′ (light projecting unit 7a ′ and light receiving unit 7b ′) is provided at a different arrangement position and a different facing distance. Thus, even if the heat storage material 1 is in a supercooled state and a subcooled destruction state inside the storage container, the light transmittance of each part of the heat storage material 1 can be detected with higher accuracy, and the state of the heat storage material 1 can be more accurately detected. Can be determined.

Next, an arrangement example of the optical sensor (light projecting unit / light receiving unit) will be described.
FIG. 9 shows an arrangement example 1 of the optical sensor. In this example, the light projecting portion 7 a and the light receiving portion 7 b (light projecting surface and light receiving surface) of the optical sensor 7 are fixed to and opposed to the mutually facing outer walls of the storage container 30 of the heat storage material 1. In this case, the entire storage container 30 may be a light transmissive material, or only the light path may be a light transmissive material, and the other part may be a light opaque material. According to this configuration, since the optical sensor is not in direct contact with the heat storage material, the optical sensor is not subjected to corrosion or dissolution action by the heat storage material, so that an inexpensive material configuration can be achieved.

  FIG. 10 shows an arrangement example 2 of the optical sensor. In this example, the light projecting portion 7 a and the light receiving portion 7 b of the optical sensor 7 are fitted and fixed to the concave portions provided on the opposing outer walls of the storage container 30 of the heat storage material 1, respectively, and are opposed to each other. Also in this case, the entire container 30 may be a light transmissive material, or only the light path may be a light transmissive material, and the other part may be a light opaque material. According to this configuration, a special part for fixing the optical sensor to the storage container is not required, and the system can be made inexpensive.

FIG. 11 shows an arrangement example 3 of the optical sensor. In this example, the light projecting unit 7a and the light receiving unit 7b of the optical sensor 7 are fitted and fixed to through holes provided in the opposing outer walls of the storage container 30 of the heat storage material 1, respectively, and the light projecting unit 7a and the light receiving unit 7b. The (light projecting surface and light receiving surface) are flush with the inner wall surface of the storage container 30 and are made to face each other. In this case, the storage container 30 may be a light opaque material.
FIG. 12 shows an arrangement example 4 of the optical sensor. In this example, the light projecting unit 7a and the light receiving unit 7b of the optical sensor 7 are fitted and fixed to through holes provided in the opposing outer walls of the storage container 30 of the heat storage material 1, respectively, and the light projecting unit 7a and the light receiving unit 7b. The (light projecting surface and light receiving surface) are protruded inward from the inner wall surface of the storage container 30 to be opposed to each other. Also in this case, the storage container 30 may be a light opaque material.

  FIG. 13 shows an arrangement example 5 of the optical sensor. In this example, the light projecting unit 7 a and the light receiving unit 7 b of the optical sensor are disposed in the storage container 30 of the heat storage material 1 and are opposed to each other. Also in this case, the storage container 30 may be a light opaque material. According to the arrangement examples 3 to 5, since the storage container can be made of a light opaque material, the heat storage material can be prevented from being deteriorated by external heat, and the long-term operation reliability of the heat storage device is improved. can do.

9 to 13, the light projecting unit 7 a and the light receiving unit 7 b are arranged symmetrically. However, the light projecting unit 7 a may be any one of the modes shown in FIGS. 9 to 13. 7b may be combined as appropriate, such as any one of FIGS.
FIG. 14 shows an arrangement example 6 of the optical sensor. A beam splitter (half mirror) 40 that reflects part of the incident light and transmits part of it is provided in the middle of the optical path from the light projecting part 7 a to the light receiving part 7 b of the optical sensor 7. Two light receiving portions 7b 'are arranged. By doing in this way, the light projection part 7a is made common, and only light-receiving part 7b, 7b 'is made plural, and the light transmittance of each part of the thermal storage material 1 is detected, and discrimination | determination precision can be improved. Note that the light projecting portion 7a and the light receiving portions 7b and 7b ′ may be attached in any manner shown in FIGS.

According to the above embodiment, as described below, there are effects of (1) execution of efficient heat collection, (2) execution of efficient heat storage, and (3) improvement of the life of the heat storage device including the heat storage material. can get.
(1) Execution of efficient heat collection (1-1) Efficiency improvement of energy consumption for nucleation It is sufficient to operate the nucleation means only when the supercooling heat storage material 1 is in a supercooled state. As a result, the energy efficiency of the heat storage device can be improved, that is, the efficiency can be improved by reducing the power consumption and power consumption.

(1-2) Improvement of reliability of heat collection Since it is possible to clarify that the heat storage material 1 is in a supercooled state in which latent heat is retained, the accuracy of heat collection is improved and the reliability of heat collection is improved. . That is, when it is desired to collect heat, it can be determined whether or not the supercoolable heat storage material 1 has latent heat, so that the accuracy of determining whether heat can be collected is significantly improved. That is, when a heat storage device having the supercooling heat storage material 1 is used and, for example, in an automobile, when defrosting a window, drying a dew condensation surface, or dehumidifying a vehicle interior by heat collection, it is possible to reliably determine whether heat collection is possible. Therefore, the comfort and driving safety of the vehicle occupants are greatly improved. Furthermore, based on the present embodiment, it is determined whether or not to nucleate and collect heat from the latent heat amount and the sensible heat amount of the heat storage material 1 and the heat capacity of the heat storage material storage container 30 with respect to the required heat amount. Also good.

(2) Execution of efficient heat storage The heat storage material 1 that has been heated and melted does not need to be reheated for heat storage as long as the supercooled state is maintained, but when the supercooled state is destroyed, When changes occur and heat storage is required, it must be heated. If the temperature of the heat storage material 1 in the heat storage device is equal to or lower than the solidification temperature, but it is unclear whether or not it is in a phase change supercooled state, reheating must be performed to store heat in the heat storage material 1, and heat storage When the material was in a supercooled state, the heat storage material in a state where latent heat storage was impossible was heated, and an action with extremely inferior heat storage efficiency had to be performed. In this regard, according to the present embodiment, since it can be determined whether or not the supercoolable heat storage material 1 is in a state capable of storing heat, the accuracy of determining whether or not to store heat is remarkably improved.

(3) Improving the life of a heat storage device including a heat storage material When collecting heat from the supercooling heat storage material 1, local cooling of the nearby supercooling heat storage material 1 by energizing the thermoelectric element 4 as a nucleation means (or Heating) and the number of times power and power are input to the impact generating element as a mechanical stimulus can be minimized. This can prevent undesired situations such as the use of high-grade materials for maintaining the durability of the nucleation means and the shortening of the maintenance frequency. In addition, by eliminating useless heating time of the supercooling heat storage material 1, it is possible to prevent thermal deterioration and oxidation deterioration of the supercooling heat storage material 1. Long-term heating or local heating of the heat storage material 1 is caused by irreversible changes or alterations in the composition of the heat storage material due to heat, generation of acidic substances or corrosion products as degradation reaction products due to chemical reactions with trace amounts of oxygen, water vapor, etc. in the storage container 30 May occur. Therefore, according to this embodiment, since it is possible to prevent the supercoolable heat storage material 1 from storing excessively, it is not necessary to use a high-corrosive high-grade, that is, expensive container material or heat transfer material. Heat can be collected without increasing the cost.

  The illustrated embodiments are merely examples of the present invention, and the present invention is not limited to those directly described by the described embodiments, and various improvements and modifications made by those skilled in the art within the scope of the claims. Needless to say, it encompasses changes.

DESCRIPTION OF SYMBOLS 1 Heat storage material 2 Heating circuit 3 Heat dissipation circuit 4 Nucleation means (thermoelectric element)
DESCRIPTION OF SYMBOLS 5 Controller 6 Temperature sensor 7 Optical sensor 7a Light projection part 7b Light-receiving part 8 Temperature sensor 11 Heat collection heat exchanger 12 Heat input heat exchanger 13 Pump 14 Flow control valve 15 Heat output heat exchanger 16 Four-way valve 21 Collection Heat exchanger 22 Heat output heat exchanger 23 Pump 24 Flow control valve 25 Blower 30 Storage container 40 Beam splitter

Claims (6)

After being heated to a melting point or higher and being in a liquid state, it is cooled to a melting point or lower in a liquid state, and a heat storage material having supercooling property,
Nucleation means for generating latent heat by giving a stimulus for activation to a supercooled heat storage material to generate solid phase nuclei,
A heat storage device comprising:
A temperature sensor for detecting the temperature of the heat storage material;
An optical sensor for detecting the light transmittance of the heat storage material;
Supercooling state determining means for determining a supercooling state of the heat storage material based on signals from the temperature sensor and the optical sensor;
A heat storage device comprising:   2. The heat storage according to claim 1, wherein the supercooling state determination unit determines that the heat storage material is in a supercooling state when a temperature of the heat storage material is lower than a melting point and a light transmittance of the heat storage material is equal to or higher than a predetermined value. apparatus.   3. The nucleation control means for operating the nucleation means on at least one condition that the supercooling state is determined by the supercooling state determination means. Heat storage device.   The heat storage device according to any one of claims 1 to 3, wherein the optical sensor includes a light projecting unit and a light receiving unit that are opposed to each other via the heat storage material.   The heat storage device according to any one of claims 1 to 4, wherein the nucleation unit is a thermoelectric element.   The heat storage device according to any one of claims 1 to 5, further comprising a heating unit that heats the heat storage material to a melting point or more and a heat radiation unit that extracts latent heat from the heat storage material.

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