JP2000346483A - Heat pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump capable of assuring a differential pressure from an atmospheric pressure by reducing a temperature drop of a metal hydride when hydrogen gas is discharged, and improving an output and an efficiency by accelerating discharging of the gas. SOLUTION: First heat exchanging containers 17, 21 in which low-temperature metal hydrides are filled are connected to second heat exchanging containers 18, 28 in which high-temperature metal hydrides are filled through pumps 11, 21. A temperature of a low-temperature thermal storage tank 35 is divided into a plurality of stages to a target temperature with an endothermic reaction brought about by discharging hydrogen gas from one to the other of the containers 17, 18 as a cold heat, and cooled and thermally stored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump which is used in a cooling and heating apparatus or the like and uses a metal hydride as a heat source.

[0002]

2. Description of the Related Art Conventionally, as a heat pump capable of performing both cooling and heating, for example, a heat pump using a metal hydride as a heat source is known as disclosed in Japanese Patent Publication No. Hei 6-23629.

[0003] The heat pump disclosed in Japanese Patent Publication No. Hei 6-23629 has two sets of metal hydride heat exchangers, one set of metal hydride heat exchangers and the other set of metal hydride heat exchangers. A hydrogen gas valve for controlling the direction of movement of the hydrogen gas, a heat medium passage for two sets of metal hydride heat exchangers, a heat source heat exchange unit, and an indoor The heat exchanger includes a heat medium valve for switching connection with the heat medium passage of the heat exchange unit, and a pressure detector for detecting a pressure in each heat exchanger.

In such a configuration, when hydrogen gas is transferred from the other set of metal hydride heat exchangers to one set of metal hydride heat exchangers, the other set of metal hydride heat exchangers While the hydrogen equilibrium pressure is higher than the hydrogen equilibrium pressure of one set of metal hydride heat exchangers, the compressor is operated at no load, and a compressor bypass path is formed to create a pressure difference between the two metal hydride heat exchangers. After the hydrogen gas has been transferred, the bypass passage is closed and the compressor is closed by the compressor after the hydrogen equilibrium pressure of the other set of metal hydride heat exchangers becomes equal to the hydrogen equilibrium pressure of the other set of metal hydride heat exchangers. The hydrogen gas is moved, and when one set of metal hydrides reaches a predetermined degree of saturation, the operation is continuously repeated by inverting the flow of the hydrogen gas.

[0005]

By the way, in the heat pump constructed as described above, the metal hydride filled in each heat exchanger is circulated around each heat exchanger filled with the metal hydride. The endothermic reaction that occurs when the hydrogen gas that has been occluded is released is taken out as cold heat, and the cooled heat source is used for cooling, etc., and the heat source that has been heated and heated with the use is returned to the heat exchanger. Back up.

[0006] Therefore, it is necessary to cool the heat source to the target temperature again in one reaction, and the temperature difference for cooling from the temperature after being used as cold to the temperature that can be used as cold becomes large.

For example, as shown in FIG. 8, when the heat source temperature after heating is 15 ° C. and the heat source temperature is cooled down to 5 ° C., the temperature difference is 10 ° C.

Since the heat transfer between the metal hydride and the heat exchanger for obtaining the temperature difference of 10 ° C. is insufficient, it is necessary to release hydrogen gas at such a speed that the heat transfer is insufficient. Therefore, as shown in FIG. 9, the temperature of the metal hydride drops rapidly (see arrow p), and eventually becomes lower than the target temperature, so that the differential pressure from the atmospheric pressure cannot be sufficiently secured. In addition, the amount of released hydrogen gas is greatly reduced. Then, due to the slow release of hydrogen gas,
Hydrogen gas flows in such a range that heat transfer between the heat exchanger and the heat source is balanced.

As a result, as shown in FIG. 10A, the heat exchanger filled with the metal hydride is rapidly cooled (the start of cooling is also accelerated), so that the heat transfer speed cannot be made in time, and the heat transfer speed is not enough. As shown in B), the temperature of the filled metal hydride drops significantly below the target temperature, making it impossible to secure a sufficient differential pressure, reducing the release rate of hydrogen gas and significantly increasing the output and efficiency. There was a problem of lowering.

As described above, the temperature must be reduced to a temperature difference of 10 ° C. while flowing around the heat exchanger, so that the release rate of hydrogen gas becomes extremely slow, and the output and efficiency are reduced.

The present invention has been made in view of the above circumstances, and a heat pump capable of preventing a temperature of a container filled with a metal hydride from being reduced more than necessary and a hydrogen gas release rate from being lowered. The purpose is to provide.

[0012]

In order to achieve the object, a first aspect of the present invention is a heat pump in which first and second containers filled with metal hydride are connected via a supply / discharge unit. In the first and second one of the containers, the endothermic reaction that occurs by releasing the hydrogen gas occluded in the metal hydride filled in the one container, while storing heat in the heat storage tank as cold heat, the temperature of the heat storage tank Cooling is divided into multiple stages to the target temperature.

As a result, the temperature drop of the metal hydride during the release of the hydrogen gas can be reduced, and the pressure difference from the atmospheric pressure can be ensured. In addition, the release of the hydrogen gas becomes faster, and the output and efficiency are improved. You. Here, a compressor or a pump can be used as the supply / discharge means.

The invention according to claim 2 is characterized in that the cooling temperature difference in the first stage when the endothermic reaction of the metal hydride is divided into a plurality of stages and cooled to the target temperature is set to 5 ° C. or less. And

Thus, the heat source can be quickly cooled. Further, it is more preferable that the output after cooling in a plurality of stages and the pressure increase width during the regeneration operation are 0.3 MPa or less.

[0016]

Next, an embodiment of a heat pump according to the present invention will be described with reference to the drawings. In this embodiment, a description will be given assuming that the air conditioner is being cooled.

In FIG. 1, reference numerals 10 and 20 denote two-system compressor units sharing one heat exchange unit 30, 40 on the indoor side and on the heat source side.

The cold heat generating unit 10 includes a pump 11, which is a supply / discharge unit, a check valve 12, valves 13 to 16, a first heat exchange container 17 as a first container, and a second heat container as a second container.
And a bypass passage 19.

The first heat exchange vessel 17 is filled with a low-temperature metal hydride, and the second heat exchange vessel 18 is filled with a high-temperature metal hydride. The metal hydrides may be the same or different.

The pump 11 allows the valves 13 to 16 to be opened and closed according to the pressure of the hydrogen gas in the heat exchange vessels 17 and 18, and allows the hydrogen gas to flow through the bypass passage 19 by the differential pressure of the hydrogen gas.

The cold heat generating unit 20 includes a pump 21 as a supply / discharge means, a check valve 22, valves 23 to 26, a first heat exchange container 27 as a first container, and a second heat exchange container 27 as a second container.
And a bypass passage 29.

The first heat exchange vessel 27 is filled with a metal hydride for low temperature, and the second heat exchange vessel 28 is filled with a metal hydride for high temperature. The metal hydrides may be the same or different.

The pump 21 includes the first and second heat exchange vessels 2
Valve 2 controlled to open and close according to the pressure of hydrogen gas at 7, 28
3 to 26 and the pressure difference between the hydrogen gas and the bypass passage 29.
Through each other.

Heat exchange unit 30 and first heat exchange vessel 1
7, a pipe 31 is provided, and a heat exchange unit 30 is provided.
A pipe 32 is provided between the first heat exchange container 27 and the first heat exchange container 27. The heat exchange unit 30 is connected to a cooling tank 34 and a low-temperature heat storage tank 35 by a pipe 33.

Heat exchange unit 40 and second heat exchange vessel 1
8, a pipe 41 is provided, and a heat exchange unit 40 is provided.
A pipe 42 is provided between the heat exchanger 28 and the heat exchange container 28. The heat exchange unit 40 is connected to a cooling tank 44 by a pipe 43.

The pipes 31, 32, 33 and the pipes 41, 42,
A heat source is provided in the tube 43. For example, heat absorption caused by discharging hydrogen gas stored in the metal hydride filled in the heat exchange container 17 to the heat exchange container 18 via the bypass passage 19 is provided. Heat storage tank for low temperature with reaction as cold
Store heat in 5.

At this time, the low-temperature heat storage tank 35 is, for example, as shown in FIG. 2, a first stage of cooling the heat source from 15 ° C. to 10 ° C. or less, and as shown in FIG.
The temperature of the heat source is lowered to the target temperature in three stages, that is, a second stage of cooling to 7 ° C. and a third stage of cooling from 7 ° C. to 5 ° C. as shown in FIG. When the low-temperature heat storage tank 35 has dropped to the target temperature (5 ° C.), it is used for cooling 36.

At this time, the heat exchange vessel 17
When the temperature of the low-temperature heat storage tank 35 approaches the target temperature when the temperature of the hydrogen gas is released from the temperature at which the hydrogen gas is discharged to 8 reaches the target temperature, the drive amount of the pump 11 and the opening degrees of the valves 13 to 16 are reduced or stopped. This allows stepwise temperature control of the heat source.

When the temperature in the low-temperature heat storage tank 35 rises to about 15 ° C. due to the use of cold heat as the cooling 36, the cooling is performed again in the order of 15 ° C. → 10 ° C. → 7 ° C. → 5 ° C. The output operation for cooling the low-temperature heat storage tank 35 is alternately performed by the system of the cold heat generating unit 10 and the system of the cold heat generating unit 20.

Therefore, when the cold heat generation unit 10 performs the output operation, the cold heat generation unit 20 performs the regeneration operation, and when the cold heat generation unit 10 performs the regeneration operation, the cold heat generation unit 20 performs the output operation.

FIG. 5B shows the temperature reduction width in the first stage, and FIG. 6 shows the temperature reduction width in the second stage.
(B) As shown in FIG. 7 (B) showing the temperature reduction in the third stage, the temperature reduction in each stage becomes smaller, and the temperature of the metal hydride drops rapidly and continuously from the target temperature. Can be prevented.

As a result, a sufficient pressure difference between the atmospheric pressure and the equilibrium hydrogen pressure of the metal hydride can be ensured.
As shown in (A), FIG. 6 (A), and FIG. 7 (A), the release rate of hydrogen increases in each temperature region (release start time becomes longer), and the heat transfer rate can be made in time.

[0033]

As described above, in the heat pump of the present invention, the endothermic reaction caused by releasing one of the hydrogen gas is stored as cold heat in the heat storage tank.
By dividing the temperature of the heat storage tank into a plurality of stages and cooling it to the target temperature, the temperature drop of the metal hydride at the time of releasing the hydrogen gas can be reduced, and the pressure difference from the atmospheric pressure can be ensured. Hydrogen gas is released faster, and output and efficiency are improved.

According to the second aspect of the present invention, the cooling of the heat source can be rapidly performed by setting the cooling temperature difference in the first stage to 5 ° C. or less.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a heat pump according to an embodiment of the present invention.

FIG. 2 is an operation graph of the temperature cooling of the heat source in the first stage.

FIG. 3 is an operation graph of the temperature cooling of the heat source in the second stage.

FIG. 4 is an operation graph of the temperature cooling of the heat source in the third stage.

5 (A) is a graph showing the relationship between the heat source flow rate and time during the temperature cooling of the heat source in the first stage, and FIG. 5 (B) is a graph showing the relationship between the heat source temperature reduction width and the time in the first stage. It is a graph which shows the relationship of.

FIG. 6A is a graph showing the relationship between the heat source flow rate and time during the temperature cooling of the heat source in the second stage, and FIG. 6B is a graph showing the relationship between the temperature reduction width and time in the second stage. It is a graph which shows the relationship of.

FIG. 7A is a graph showing the relationship between the heat source flow rate and time during the temperature cooling of the heat source in the third stage, and FIG. 7B is a graph showing the relationship between the temperature decrease width and time in the third stage. It is a graph which shows the relationship of.

FIG. 8 is a graph showing an operation of temperature cooling of a heat source, showing a conventional heat pump.

FIG. 9 is an operation graph showing a state where a failure has occurred in cooling the heat source.

FIG. 10A is a graph showing the relationship between the heat source flow rate and time when the heat source is cooled down, and FIG. 10B is a graph showing the relationship between the temperature decrease of the heat source and time.

[Explanation of symbols]

 11 Pump (supply / discharge means) 17 Heat exchange container (first container) 18 Heat exchange container (second container) 21 Pump (supply / discharge means) 27 Heat exchange container (first container) 28 ... heat exchange container (second container) 35 ... for cooling (heat storage tank)

Claims (2)

[Claims] 1. A heat pump in which first and second containers filled with metal hydride are connected via a supply / discharge means, wherein the metal hydride filled in one of the first and second containers is provided. A heat pump characterized in that an endothermic reaction caused by releasing stored hydrogen gas is stored as cold heat in a heat storage tank, and the endothermic reaction of metal hydride is divided into a plurality of stages and cooled to a target temperature. 2. The heat pump according to claim 1, wherein the cooling temperature difference in the first stage when the endothermic reaction of the metal hydride is divided into a plurality of stages and cooled to a target temperature is 5 ° C. or less.