Patent Description:
In general, in a conventional engine automobile, a mechanism operated as a mechanical compression type air conditioning device (air conditioner) is only a cooling device for cooling a compartment and the compartment is warmed by using heat of cooling water of an engine. This is because the air conditioner cannot be used in winter due to frost formation. Even if the air conditioner is used, the air conditioner is used only above approximately <NUM> and a heater utilizing exhaust heat of the engine is used for warming the compartment when the outside air temperature is <NUM> or less.

In addition, an electric car has been developed in recent years. For example, Patent Document <NUM> discloses an air conditioner for the electric car constituted of a heat pump type air conditioning system, a heat storage type air conditioning system and a combustion type air conditioning system capable of securing sufficient heating capacity even at a low temperature and reducing burden to a battery.

However, in the conventional air conditioner for the electric cars shown in Patent Document <NUM>, for example, a problem is that the air conditioner occupies large space since the air conditioner is a large device. In addition, a problem is that the system becomes large scale as a whole because complicated control is required. Therefore, in order to cope with the above described problems, it can be considered that heat is stored by electric power using chemical heat storage and the heat is used for a heater (heating device). <CIT> discloses a thermochemical heat accumulator with a storage medium for heat storage via a reversible gas-solid reaction, wherein the heat accumulator can be operated using an oxygen-containing process gas and wherein the storage medium is designed as a multi-component system with at least two metal oxides.

However, when the chemical heat storage or the like is used for storing the heat by the electric power and the heat is used for the heater, an evaporator and a condenser are required. Thus, large space is needed and the weight is increased. In addition, the control of the evaporator and the condenser is required. As a result, a problem is that the system becomes large scale. Furthermore, if water is used as a reaction medium, the water freezes. Thus, chlorofluorocarbon, ammonia and the like are used in many cases since they do not freeze. However, a problem is that the system is enlarged since the heat storage amount per volume is small.

The present invention is made for solving the above described problems and aims for providing a heat storage device having a simple and small shape without occupying large space when mounted on the electric car and capable of storing and releasing heat efficiently without using water so that the heat storage device is used as a heater.

In order to achieve the purpose described above, the heat storage device of the present invention includes: a heat storage material configured to be oxidized and deoxidized by a temperature control operation; a heat transfer material for heating the heat storage material; at least a pair of electrodes configured to be connected to a power source for heating the heat transfer material; and a container containing the heat storage material, the heat transfer material and the at least a pair of electrodes; an upstream valve provided on an upstream inlet of the container for shielding an inside of the container from an outside of the container; and a downstream valve provided on a downstream outlet of the container for shielding the inside of the container from the outside of the container.

When the heat storage device of the present invention is used, because the heat storage device is operated only by the air and the electric power, the structure can be simple and the whole volume can be small. The heat can be stored and released efficiently since the electric power is converted into heat of chemical reaction in the air and densely stored and the stored heat can be extracted at high rate at an arbitrary time when the heat is needed.

The present invention aims for providing a heat storage device having a simple and small shape without occupying large space when mounted on the electric car and capable of storing (accumulating) and releasing (radiating) heat efficiently without using water so that the heat storage device is used as a heater. The present invention relates to the heat storage device operated by the air and the electric power.

Hereafter, the embodiments of the present invention will be explained in detail with reference to the drawings.

A heat storage device concerning the embodiment <NUM> of the present invention applies the chemical heat storage using the oxidation-reduction (deoxidization) reaction achieved by the temperature control operation. The heat storage device is operated by the air and the electric power.

Here, <FIG> is a table showing examples of reaction system of the chemical heat storage using the oxidation-reduction reaction. <FIG> shows the reaction formula and the reaction temperature of the substances to be oxidized and deoxidized (reduced) by the temperature control operation and the melting point of the substances. In the embodiment <NUM>, the explanation will be made by using the following example of the reaction shown in No. <NUM> of <FIG>.

"2Co<NUM>O<NUM> (tricobalt tetroxide) → 6CoO (cobalt monoxide) + O<NUM> (oxygen)".

<FIG> is a drawing schematically showing an example of a brief configuration of the heat storage device in the embodiment <NUM> of the present invention. In <FIG>, the air is made to flow through a heat storage material <NUM> in one direction (i.e., from the left to the right direction in the figure). The heat storage device <NUM> includes: a heat storage material <NUM> configured to be oxidized and deoxidized by a temperature control operation; a heat transfer material <NUM> for heating the heat storage material <NUM>; at least a pair of electrodes <NUM>, <NUM> (the at least a pair of electrodes are a first electrode <NUM> and a second electrode <NUM> in the embodiment <NUM>) configured to be connected to a power source (electric power source) for heating the heat transfer material <NUM>; a container <NUM> containing the heat storage material <NUM>, the heat transfer material <NUM> and the at least a pair of electrodes <NUM>, <NUM>; and an upstream valve <NUM> and a downstream valve <NUM> for shielding the inside of the container <NUM> from the outside of the container <NUM>. The upstream valve <NUM> is provided on an upstream inlet of the container <NUM>, and the downstream valve <NUM> is provided on a downstream outlet of the container <NUM>. Although the devices related to the temperature control operation such as a thermometer and a temperature adjusting unit are connected to the heat storage device <NUM>, the illustration and explanation of these devices are omitted.

<FIG> is a drawing schematically showing another example of a brief configuration of the heat storage device in the embodiment <NUM>. A heat storage device <NUM>' shown in <FIG> includes: a heat storage material <NUM> configured to be oxidized and deoxidized by a temperature control operation; a heat transfer material <NUM> for heating the heat storage material <NUM>; and at least a pair of electrodes <NUM>, <NUM> configured to be connected to a power source for heating the heat transfer material <NUM>. Also in <FIG>, the air is made to flow through the heat storage material <NUM> in one direction (i.e., from the left to the right direction in the figure).

In <FIG> and <FIG>, the diagonal grids indicate the heat transfer material <NUM>, and dots indicate the heat storage material <NUM>. Namely, in the example shown in <FIG>, the heat transfer material <NUM> is arranged on an approximately entire inner part of the container <NUM> from near the inlet of the container <NUM> to near the outlet of the container <NUM>. The heat transfer material <NUM> is filled with the heat storage material <NUM> so that the heat transfer material <NUM> carries the heat storage material <NUM>. Also in the example shown in <FIG>, the heat transfer material <NUM> is filled with the heat storage material <NUM> and the heat transfer material <NUM> carries the heat storage material <NUM>.

In the example shown in <FIG>, in the at least a pair of electrodes (first electrode <NUM> and second electrode <NUM> in the embodiment <NUM>), the first electrode <NUM> is arranged near the inlet in the container <NUM> (position near the upstream valve <NUM>). Namely, the first electrode <NUM> is arranged on an upstream side end part in a flow path of the air flowing through the heat storage material <NUM>. The second electrode <NUM> is arranged near the outlet in the container <NUM> (position near the downstream valve <NUM>). Namely, the second electrode <NUM> is arranged on a downstream side end part in a flow path of the air flowing through the heat storage material <NUM>. On the other hand, in the example shown in <FIG>, the pair of electrodes <NUM>, <NUM> is arranged on the positon not located on the upstream side and the downstream side. The pair of electrodes <NUM>, <NUM> can be arranged on the position shown in <FIG> as long as the pair of electrodes <NUM>, <NUM> can heat the whole heat storage material <NUM> evenly.

The heat transfer material <NUM> for heating the heat storage material <NUM> and the at least a pair of electrodes <NUM>, <NUM> constitute an electric heater. The heat transfer material <NUM> is heated by connecting the at least a pair of electrodes <NUM>, <NUM> to the power source. Namely, the electric heater is comprised of the heat transfer material <NUM> and the at least a pair of electrodes <NUM>, <NUM>, and the at least a pair of electrodes is configured to be connected to the power source for heating the heat transfer material <NUM>.

As described above, because the reaction of No. <NUM> in the table shown in <FIG> is used in the embodiment <NUM>, the heat storage material <NUM> is the tricobalt tetroxide (or the cobalt monoxide).

In the embodiment <NUM>, SiC (silicon carbide) porous body is used as the heat transfer material <NUM>. As described above, the heat transfer material <NUM> formed of the SiC porous body is arranged on an approximately entire inner part of the container <NUM> from near the inlet (upstream side) of the container <NUM> to near the outlet (downstream side) of the container <NUM>. Namely, the heat transfer material <NUM> is arranged on a part sandwiched by the first electrode <NUM> and the second electrode <NUM>. Thus, the electric heater is formed. Since the porous body portion of the heat transfer material <NUM> is filled with the heat storage material <NUM>, the heat storage material <NUM> can be also heated when the heat transfer material <NUM> is heated. As described above, because the heat transfer material <NUM> carries the heat storage material <NUM>, the whole heat storage material <NUM> can be rapidly and evenly heated. It is possible to store or release the heat in only several minutes.

Note that the heat transfer material <NUM> can be any material as long as the heat transfer material <NUM> can heat the heat storage material <NUM> filling the inside of the container <NUM>. When the heating temperature can be lowered, the material such as stainless-steel can be used. As for the shape, it is possible to arrange a rod-shaped heat transfer material <NUM>' along a central axis of the container <NUM> and fill the container <NUM> with the heat storage material <NUM> so that the heat storage material <NUM> surrounds the periphery of the heat transfer material <NUM>', for example.

<FIG> are flow charts showing an example of operations of storing and releasing heat in the heat storage device <NUM> in the embodiment <NUM>. <FIG> shows the operation of storing the heat and <FIG> shows the operation of releasing the heat.

When storing the heat, as shown in <FIG>, first of all, whether or not the upstream valve <NUM> and the downstream valve <NUM> are opened is checked (Step ST0). Normally, because the upstream valve <NUM> and the downstream valve <NUM> are opened after the later described operation of releasing the heat, the operation of storing the heat can be started from that state (opened state). If the upstream valve <NUM> and the downstream valve <NUM> are not opened (No in Step ST0), the downstream valve <NUM> and the upstream valve <NUM> are opened to introduce the air in the container <NUM> (Step ST1). Then, the first electrode <NUM> and the second electrode <NUM> are connected to the power source (switch SW1 shown in <FIG> is closed) to supply DC or AC power. Thus, the heat transfer material <NUM> containing the heat storage material <NUM> is heated (Step ST2). Consequently, the heat storage material <NUM> is heated.

When the heat storage material <NUM> reaches a certain temperature (predetermined temperature) (Yes in Step ST3), the heat storage material <NUM> releases the oxygen. Namely, the heat storage material <NUM> is changed into the substance which is deoxidized compared to the original state (i.e., the substance in which the heat is stored). After the release of the oxygen is finished (Yes in Step ST4), the upstream valve <NUM> and the downstream valve <NUM> are closed to function as shutoff valves (Step ST5). Thus, the heat storage material <NUM> is prevented from being oxidized again by the air entering from the outside. Whether or not the release of the oxygen is finished (Step ST4) is judged by measuring the temperature to know whether or not the endothermic reaction is finished.

When releasing the heat, as shown in <FIG>, first of all, whether or not the upstream valve <NUM> is closed is checked (Step ST10). Normally, the upstream valve <NUM> and the downstream valve <NUM> are closed after the operation of storing the heat (after Step ST5). If the upstream valve <NUM> is not closed (No in Step ST10), the upstream valve <NUM> is closed and then the downstream valve <NUM> is opened (Step ST11). Also when releasing the heat, the first electrode <NUM> and the second electrode <NUM> are connected to the power source (switch SW1 shown in <FIG> is closed) to supply DC or AC power. Thus, the heat transfer material <NUM> is heated (Step ST12). Consequently, the heat storage material <NUM> is heated.

When the heat storage material <NUM> reaches a certain temperature (predetermined temperature) (Yes in Step ST13), the upstream valve <NUM> which is a shutoff valve of the upstream side located near the first electrode <NUM> is opened (Step ST14). Thus, the air is introduced in the container <NUM> from the outside (Step ST15). Consequently, the oxygen contained in the air is reacted with the heat storage material <NUM> for generating the heat. The flowing air is heated by the generated heat, and the heated air is transferred to the downstream side. Thus, the temperature of the heat storage material <NUM> is increased so that the oxidation reaction is started. As described above, the oxidation reaction is caused over the whole heat storage device <NUM> to release and supply the heat.

<FIG> is a graph showing a relation between a temperature and an oxygen concentration in a state that cobalt monoxide (CoO) and tricobalt tetroxide (Co<NUM>O<NUM>) are present in a mixed gas of oxygen and nitrogen. The horizontal axis shows the temperature and the vertical axis shows the oxygen partial pressure (oxygen pressure). In <FIG>, the cobalt exists as the tricobalt tetroxide at an area located at the left side of the curved line shown by the solid line, and the cobalt exists as the cobalt monoxide at an area located at the right side of the curved line. The straight line shown by dashed-and-dotted line in <FIG> shows <NUM> % in the oxygen concentration. The straight line shown by dashed-and-dotted line crosses the curved line shown by the solid line at approximately <NUM> in the temperature.

Namely, under the condition of <NUM>% in the oxygen concentration, which is the same oxygen concentration as the air, the cobalt exists as the tricobalt tetroxide at the temperature less than approximately <NUM>, and the cobalt exists as the cobalt monoxide at the temperature more than approximately <NUM>. Accordingly, when the cobalt monoxide is placed in the air having the temperature of approximately <NUM> or less, the cobalt monoxide is oxidized and converted into the tricobalt tetroxide while releasing reaction heat. When the tricobalt tetroxide is placed in the air having the temperature of approximately <NUM> or more, the tricobalt tetroxide is deoxidized and converted into the cobalt monoxide while absorbing the heat. By using the property of the above described chemical equilibrium, the reduction (deoxidization) of the tricobalt tetroxide and the oxidization of the cobalt monoxide are reversibly repeated to store the heat and release the heat while controlling the temperature of the material in the presence of the air.

<FIG> are explanatory drawings showing a reduction behavior (<FIG>) from the tricobalt tetroxide to the cobalt monoxide and an oxidization behavior (<FIG>) from the cobalt monoxide to the tricobalt tetroxide under the condition of flowing air. The values are measured using a thermobalance.

<FIG> shows the result of analyzing the reduction behavior from the particles of the tricobalt tetroxide (several milligrams) to the cobalt monoxide under the condition of flowing air while changing the temperature. The values are measured using a thermobalance. The horizontal axis shows the time and the vertical axis shows the conversion in reduction reaction. <FIG> shows the result of analyzing the oxidization behavior from the cobalt monoxide to the particles of the tricobalt tetroxide under the condition of flowing air while changing the temperature. The values are measured using a thermobalance. Same as <FIG>, the horizontal axis shows the time and the vertical axis shows the conversion in oxidization reaction.

<FIG> shows five patterns of the temperatures <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. The solid line A shows the case of the temperature <NUM>, the solid line B shows the case of the temperature <NUM>, the dashed-and-dotted line C shows the case of the temperature <NUM>, the dashed-and-dotted line D shows the case of the temperature <NUM>, and the solid line E shows the case of the temperature <NUM>. Referring to <FIG>, it can be understood that the reduction reaction is advanced at the temperature of <NUM> or more in the presence of the air. It can be also confirmed that the rate of the reduction reaction increases as the temperature increases and the reduction reaction finishes within approximately <NUM> seconds at the temperature of <NUM> or more.

<FIG> shows five patterns of the temperatures <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. The solid line F shows the case of the temperature750°C, the solid line G shows the case of the temperature773°C, the dashed-and-dotted line H shows the case of the temperature795°C, the solid line J shows the case of the temperature <NUM>, and the dashed-and-dotted line K shows the case of the temperature <NUM>. Referring to <FIG>, it can be understood that the oxidization reaction is advanced at the temperature of <NUM> or more in the presence of the air. It can be also confirmed that the oxidization reaction is rapidly advanced until <NUM> seconds have passed after the oxidization reaction is started, then the reaction rate is reduced and the oxidization reaction is continued until <NUM> seconds.

It can be also confirmed that the oxidation operation and the reduction operation shown in <FIG> can be reversibly repeated.

<FIG> is an explanatory drawing showing an example of the behavior of storing heat (reduction behavior) under the condition of flowing high temperature air. The horizontal axis shows the time and the vertical axis shows the temperature. In the above described <FIG>, it is confirmed by using the thermobalance that the reduction (heat storage) and the oxidization (heat release) can be reversibly repeated under the condition of flowing air. Based on the above described fact, the reversibility of the operations of the reduction (heat storage) and the oxidization (heat release) and the reaction rate are considered similar to the experiment of the thermobalance. Assuming to be a device, approximately <NUM> gram of the tricobalt tetroxide (heat storage material <NUM>) is carried on the porous body of silicon carbide (heat transfer material <NUM>) and placed in an electric heating furnace.

In <FIG>, the graph shown by the solid line shows the state where the temperature of the heat storage material <NUM> is changed with time at near the center of the filled layer (i.e., near the center of the container <NUM> in which the heat storage material <NUM> is contained in the heat storage device <NUM> shown in <FIG>). The graph shown by the dashed-and-dotted line shows the state where the temperature of the heat storage material <NUM> is changed with time at near the outer wall of the filled layer (i.e., near the inner wall of the container <NUM> in which the heat storage material <NUM> is contained in the heat storage device <NUM> shown in <FIG>).

First, only the oxygen is supplied at a rate of <NUM> litters/minute while keeping the temperature of the tricobalt tetroxide at <NUM>. Then, the nitrogen is added at a rate of <NUM> litters/minute so that the oxygen concentration becomes <NUM>% which is almost same as the oxygen concentration of the air (the oxygen concentration of the air: <NUM>%). As a result, it can be confirmed that the temperature in the filled layer of the tricobalt tetroxide rapidly decreases, the endothermic reaction is advanced and the reaction finishes in approximately <NUM> seconds.

<FIG> is an explanatory drawing showing an example of a behavior of releasing heat (oxidization behavior) under the condition of flowing high temperature air. The horizontal axis shows the time and the vertical axis shows the temperature change amount. When the tricobalt tetroxide (heat storage material <NUM>) carried on the porous body of silicon carbide (heat transfer material <NUM>) is reduced and changed to the heat storage material <NUM> of the cobalt monoxide, the possibility and the reaction rate are considered for the operation of oxidizing the heat storage material <NUM> of the cobalt monoxide to the tricobalt tetroxide again to release the heat.

In <FIG>, same as <FIG>, the graph shown by the solid line shows the state where the temperature of the heat release (oxidization) is changed with time at near the center of the filled layer. The graph shown by the dashed-and-dotted line shows the state where the temperature of the heat release (oxidization) is changed with time at near the outer wall of the filled layer. In both the solid line and the dashed-and-dotted line of <FIG>, the line with the symbol L indicates the situation when the initial temperature of the cobalt monoxide is <NUM> and the supplying rate of the air is <NUM> litters/minute, the line with the symbol M indicates the situation when the initial temperature of the cobalt monoxide is <NUM> and the supplying rate of the air is <NUM> litters/minute, and the line with the symbol N indicates the situation when the initial temperature of the cobalt monoxide is <NUM> and the supplying rate of the air is <NUM> litters/minute.

After the reduction operation explained in <FIG> is finished, the upstream valve <NUM> located at the inlet (upstream side) and the downstream valve <NUM> located at the outlet (downstream side) are closed and the temperature of the cobalt monoxide is reduced to <NUM> or <NUM> as the initial temperature. Then, the upstream valve <NUM> located at the inlet (upstream side) and the downstream valve <NUM> located at the outlet (downstream side) are opened again to supply the air. As a result, it can be confirmed that the temperature in the filled layer rapidly increases and the oxidization reaction is advanced (heat is released in <NUM> seconds).

As explained above, the heat storage device <NUM> is operated only by the air and the electric power. The heat storage device <NUM> can be downsized because the heat storage device <NUM> has a simple structure comprised of: a heat storage material <NUM>; a heat transfer material <NUM> for heating the heat storage material <NUM>; at least a pair of electrodes <NUM>, <NUM>; a container <NUM> containing the heat storage material <NUM>, the heat transfer material <NUM> and the at least a pair of electrodes <NUM>, <NUM>; and an upstream valve <NUM> and a downstream valve <NUM> for shielding the inside of the container <NUM> from the outside of the container <NUM>.

Consequently, the heat storage device of the embodiment <NUM> does not occupy large space when mounted on the electric car. Furthermore, the heat can be stored and released efficiently because the electric power is converted into heat of chemical reaction in the air and densely stored and the stored heat can be extracted at high rate at an arbitrary time when the heat is needed. Since the water is not required when the heat storage device is used as a heater, the heat storage device can be used without problems even in winter.

As explained above, when the heat storage device of the embodiment <NUM> is used, because the heat storage device is operated only by the air and the electric power, the structure can be simple and the shape can be small. The heat can be stored and released efficiently because the electric power is converted into heat of chemical reaction in the air without requiring a special environment and densely stored and the stored heat can be extracted at high speed at an arbitrary time when the heat is needed.

Same as the embodiment <NUM>, the heat storage device of the embodiment <NUM> of the present invention applies the chemical heat storage using the oxidation-reduction reaction achieved by the temperature control operation. The heat storage device is operated by the air and the electric power. Also in the embodiment <NUM>, the explanation will be made by using the following example of the reaction shown in No. <NUM> of <FIG>.

<FIG> is a drawing schematically showing an example of a brief configuration of a heat storage device in the embodiment <NUM>. Note that the same reference signs are assigned to the same configuration explained in the embodiment <NUM> and redundant explanation will be omitted. The difference between a heat storage device <NUM> of the embodiment <NUM> shown in <FIG> and the heat storage device <NUM> of the embodiment <NUM> shown in <FIG> is the number of the electrodes provided (arranged).

As shown in <FIG>, the heat storage device <NUM> of the embodiment <NUM> includes: a heat storage material <NUM> configured to be oxidized and deoxidized by a temperature control operation; a heat transfer material <NUM> for heating the heat storage material <NUM>; at least a pair of electrodes <NUM>, <NUM>, <NUM> (the at least a pair of electrodes is a first electrode <NUM>, a second electrode <NUM> and a third electrode <NUM> in the embodiment <NUM>) configured to be connected to a power source for heating the heat transfer material <NUM>; a container <NUM> containing the heat storage material <NUM>, the heat transfer material <NUM> and the at least a pair of electrodes <NUM>, <NUM>, <NUM>; and an upstream valve <NUM> and a downstream valve <NUM> for shielding the inside of the container <NUM> from the outside of the container <NUM>. The upstream valve <NUM> is provided on an upstream inlet of the container <NUM>, and the downstream valve <NUM> is provided on a downstream outlet of the container <NUM>. Same as the heat storage device <NUM> of the embodiment <NUM>, although the devices related to the temperature control operation such as a thermometer and a temperature adjusting unit are connected to the heat storage device <NUM>, the illustration and explanation of these devices are omitted.

The heat storage device <NUM> of the embodiment <NUM> includes: the first electrode <NUM> provided near the inlet in the container <NUM> (position near the upstream valve <NUM>, i.e., an upstream side end part in a flow path of the air flowing through the heat storage material <NUM>); and the second electrode <NUM> provided near the outlet in the container <NUM> (position near the downstream valve <NUM>, i.e., a downstream side end part in a flow path of the air flowing through the heat storage material <NUM>) as the at least a pair of electrodes. In contrast, the heat storage device <NUM> of the embodiment <NUM> includes: the first electrode <NUM> provided near the inlet in the container <NUM> (position near the upstream valve <NUM>, i.e., an upstream side end part in a flow path of the air flowing through the heat storage material <NUM>); the second electrode <NUM> provided near the outlet in the container <NUM> (position near the downstream valve <NUM>, i.e., a downstream side end part in a flow path of the air flowing through the heat storage material <NUM>); and additionally the third electrode <NUM> provided near the first electrode <NUM> as the at least a pair of electrodes.

As shown in <FIG>, the third electrode <NUM> is arranged near the inlet in the container <NUM> (position near the upstream valve <NUM>) same as the first electrode <NUM>. Namely, the third electrode <NUM> is arranged on an upstream side end part in a flow path of the air flowing through the heat storage material <NUM>. In addition, the third electrode <NUM> is arranged adjacent to the first electrode <NUM> so that the second electrode <NUM> is nearer to the third electrode <NUM> than the first electrode <NUM>. As described above, the second electrode <NUM> is arranged near the outlet in the container <NUM> (position near the downstream valve <NUM>). Namely, the second electrode <NUM> is arranged on a downstream side end part in a flow path of the air flowing through the heat storage material <NUM>.

The electric heater is comprised of the heat transfer material <NUM> for heating the heat storage material <NUM> and the at least a pair of electrodes <NUM>, <NUM>, <NUM>. The heat transfer material <NUM> is heated by connecting any two of the at least a pair of electrodes <NUM>, <NUM>, <NUM> to the power source. Namely, the electric heater is comprised of the heat transfer material <NUM> and the at least a pair of electrodes <NUM>, <NUM>, <NUM> and the power source is configured to be connected to any two of the at least a pair of electrodes <NUM>, <NUM>, <NUM> for heating the heat transfer material <NUM>.

Since the reaction of No. <NUM> in the table shown in <FIG> is used also in the embodiment <NUM>, the heat storage material <NUM> is the tricobalt tetroxide.

Also in the embodiment <NUM>, SiC (silicon carbide) porous body is used as the heat transfer material <NUM>. The heat transfer material <NUM> formed of the SiC (silicon carbide) porous body is arranged on an approximately entire inner part of the container <NUM> from near the inlet (upstream side) of the container <NUM> to near the outlet (downstream side) of the container <NUM>. Namely, the heat transfer material <NUM> is arranged on a part sandwiched by the first electrode <NUM> and the second electrode <NUM>. Thus, the electric heater is formed. Since the porous body portion of the heat transfer material <NUM> is filled with the heat storage material <NUM>, the heat storage material <NUM> can be also heated when the heat transfer material <NUM> is heated. As described above, because the heat transfer material <NUM> carries the heat storage material <NUM>, the whole heat storage material <NUM> can be rapidly and evenly heated. It is possible to store or release the heat in only several minutes.

<FIG> are drawings showing a partial and brief configuration of an experimental demonstration device of the heat storage device <NUM> in the embodiment <NUM> of the present invention. <FIG> is a perspective view showing a brief configuration of the container <NUM> and the electrodes <NUM>, <NUM>, <NUM> of the demonstration device of the heat storage device <NUM>. <FIG> is a detailed cross-sectional view of the electrode <NUM>. <FIG> is a cross sectional view of an inside of the container <NUM> schematically showing a part of the heat transfer material <NUM> (SiC porous body) in which the heat storage material <NUM> is contained and the positional relation of the electrodes <NUM>, <NUM>, <NUM>. Note that the material of the electrode <NUM> is SiC (silicon carbide) and an insulation coating is applied on the slant line part of <FIG>. The electrodes <NUM>, <NUM> are made of same material and have same structure as the electrode <NUM> shown in <FIG>.

As shown in <FIG>, the container <NUM> of the heat storage device <NUM> has a cylindrical shape having a diameter of <NUM> (<NUM>) and a height (length) of <NUM> (<NUM>). The heat transfer material <NUM> made of the SiC porous body is arranged on an approximately three quarters (<NUM> in the length of <NUM>) of the inner part of the container <NUM> and the heat transfer material <NUM> (SiC porous body) is filled with the heat storage material <NUM>. Accordingly, the heat storage material <NUM> is also arranged on an approximately three quarters of the inner part of the container <NUM>. Note that the size and the shape of the container <NUM> are not limited to the above described example. The experiment was carried out also for the cylindrical container having a length of <NUM> which is smaller than the container of the above described example. Thus, the container is simple and small.

<FIG> are explanatory drawings showing an example of operations of storing and releasing heat in the heat storage device <NUM> in the embodiment <NUM> of the present invention. <FIG> shows the operation of storing heat and <FIG> shows the operation of releasing heat. Note that the illustration of the flow chart of this example is omitted because it is same as the flow chart of the embodiment <NUM> shown in <FIG>.

When storing heat, as shown in <FIG>, the upstream valve <NUM> is opened to introduce the air into the container <NUM>, and the first electrode <NUM> and the second electrode <NUM> are connected to the power source (switch SW1 shown in <FIG> is closed and SW2 shown in <FIG> is connected to the second electrode <NUM> to get the connection state shown in <FIG>) to supply DC or AC power. Thus, the heat transfer material <NUM> in which the heat storage material <NUM> is contained is heated. Consequently, the heat storage material <NUM> is heated. When the heat storage material <NUM> reaches a certain temperature (predetermined temperature), the heat storage material <NUM> releases the oxygen. Namely, the heat storage material <NUM> is changed into the substance which is reduced compared to the original state (i.e., the substance in which the heat is stored). After the release of the oxygen is finished, the upstream valve <NUM> and the downstream valve <NUM> are closed to function as shutoff valves. Thus, the heat storage material <NUM> is prevented from being oxidized again by the air entering from the outside. Whether or not the release of the oxygen is finished is judged by measuring the temperature to know whether or not the endothermic reaction is finished.

When releasing heat, as shown in <FIG>, after the downstream valve <NUM> is opened, the first electrode <NUM> and the third electrode <NUM> are connected to the power source (switch SW1 shown in <FIG> is closed and SW2 shown in <FIG> is connected to the third electrode <NUM> side to get the connection state shown in <FIG>) to supply DC or AC power. Thus, a part of the heat transfer material <NUM> is heated and the rest of the heat transfer material <NUM> is gradually heated by heat transfer so that the entire heat transfer material <NUM> is heated. Consequently, the heat storage material <NUM> is heated. When the heat storage material <NUM> reaches a certain temperature (predetermined temperature), the upstream valve <NUM> which is a shutoff valve of the upstream side located near the first electrode <NUM> is opened. Thus, the air is introduced in the container <NUM> from the outside. Consequently, the oxygen contained in the air is reacted with the heat storage material <NUM> for generating the heat. The flowing air is heated by the generated heat, and the heated air is transferred to the downstream side. Thus, the temperature of the heat storage material <NUM> is increased so that the oxidation reaction is started. The oxidation reaction is gradually started toward the downstream side. Consequently, the oxidation reaction is caused in the whole heat storage device <NUM> to release and supply the heat.

As described above, in the embodiment <NUM>, when releasing heat, the first electrode <NUM> and the third electrode <NUM> which are arranged near the inlet (upstream side) of the container <NUM> are connected for heating the heat storage material <NUM>. In the case where the duration time is short from finishing heat storing to the starting heat releasing, for example, the heat storage material <NUM> can be gradually heated from near the inlet of the container <NUM> to near the outlet of the container <NUM> by a small amount of electric power. Thus, there is a merit of saving energy.

Same as the heat storage device <NUM> of the embodiment <NUM>, the heat storage device <NUM> of the embodiment <NUM> is operated only by the air and the electric power. The heat storage device <NUM> can be downsized because the heat storage device <NUM> has a simple structure comprised of: a heat storage material <NUM>; a heat transfer material <NUM> for heating the heat storage material <NUM>; at least a pair of electrodes <NUM>, <NUM>, <NUM>; a container <NUM> containing the heat storage material <NUM>, the heat transfer material <NUM> and the at least a pair of electrodes <NUM>, <NUM>, <NUM>; and an upstream valve <NUM> and a downstream valve <NUM> for shielding the inside of the container <NUM> from the outside of the container <NUM>.

As explained above, same as the heat storage device of the embodiment <NUM>, when the heat storage device of the embodiment <NUM> is used, because the heat storage device is operated only by the air and the electric power, the shape can be simple and small. The heat can be stored and released efficiently because the electric power is converted into heat of chemical reaction in the air without requiring a special environment and densely stored and the stored heat can be extracted at high rate at an arbitrary time when the heat is needed.

Although the heat transfer material <NUM> and the containers <NUM>, <NUM> are described as separate components in the heat storage devices <NUM>, <NUM> of the above described embodiments <NUM>, <NUM>, these components can be integrated. For example, the heat transfer material <NUM> can have the function of the containers <NUM>, <NUM>.

As described above, in the heat storage device of the present invention, the electric power is converted into heat of chemical reaction in the air and densely stored and the stored heat can be extracted at high rate at an arbitrary time when the heat is needed. Therefore, the heat storage device of the present invention can be also applied to rapid heating of the electric car, heat recovery of high-temperature batch furnace or the like without being limited to the electric car. It is also possible that the heat transfer material is heated by introducing high-temperature exhaust gas of <NUM> as a heat source for heating the heat transfer material only when the operation of storing heat in the present invention (i.e., when the heat storage material is reduced).

Note that various embodiments can be freely combined, any configurations of the embodiments can be modified, and any configurations of the embodiments can be omitted in the present invention within the scope of the invention as defined in the appended claims.

Claim 1:
A heat storage device (<NUM>, <NUM>', <NUM>), comprising:
a heat storage material (<NUM>) configured to be oxidized and deoxidized by a temperature control operation; characterized in that the heat storage device comprises
a heat transfer material (<NUM>, <NUM>') for heating the heat storage material (<NUM>); and
at least a pair of electrodes configured to be connected to a power source for heating the heat transfer material (<NUM>, <NUM>').