JPH0391661A - Refrigerator employing hydrogen storage alloy - Google Patents

Abstract

PURPOSE:To defrost effectively without affecting the cooling efficiency of a refrigerator by supplying refrigerant to a refrigeration load by way of a plurality of low temperature side reaction tanks when shifting hydrogen transfer operation. CONSTITUTION:A refrigerator comprises a plurality of high temperature side reaction tanks 1 and 1' which are built in with high temperature hydrogen storage alloy and a plurality of low temperature side reaction tanks 2 and 2' which are built in with low temperature hydrogen storage alloy, which are all connected with each other refrigerant is supplied to refrigeration load by way of a plurality of low temperature side reaction tanks 2 and 2' when shifting hydrogen transfer operation. Therefore, sensible heat collection takes place in the reaction tanks to some degree, which makes it possible to eliminate frost, preventing the in-flow of much heat into a refrigerator during operation shift. It is, therefore, possible to defrost effectively without lowering the cooling efficiency of the refrigerator.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a refrigeration system using a hydrogen storage alloy.

(B) Conventional technology During continuous operation of a refrigeration system, there is a problem in that moisture in the air condenses and freezes on the cold heat generation circuit, leading to a decrease in the refrigeration capacity, and some kind of defrosting countermeasure is essential. Conventional refrigeration systems are well known, such as those that utilize the latent heat of vaporization of refrigerants such as fluorocarbons and ammonia, and those that utilize the Bertier effect of semiconductors. Currently, in refrigeration systems that utilize latent heat of vaporization, defrosting is performed by periodically circulating a high-temperature heat medium through a cold heat generating circuit or by heating the cold heat generating section with a heater.

Furthermore, in a refrigeration system that utilizes the Beltier effect, the direction of the current is reversed to heat the cold heat generating section and defrost it.

In either case, it is necessary to temporarily stop the system, which is originally capable of continuous operation, and switch to defrosting mode, which may complicate the equipment, complicate the operation control method, or reduce refrigeration efficiency. There was a problem.

By the way, in addition to the above-mentioned refrigeration equipment, there is also a
As shown in No. 55, a device is disclosed that utilizes the endothermic reaction of the hydrogen absorbing alloy, which is a new material, when hydrogen is released.

This refrigeration method is basically a batch system, and usually two sets of four hydrogen storage alloy tanks are used, and continuous operation is achieved by alternately operating them.

However, refrigeration systems using hydrogen storage alloys are currently in the research and development stage, and the problem of defrosting during long-term continuous operation has not been sufficiently studied.

(c) Problems to be Solved by the Invention The present invention aims to effectively defrost a refrigeration system using a hydrogen storage alloy without affecting the cooling efficiency of the refrigeration system.

(d) Means for solving the problem The present invention has been made in view of the above points,
Multiple high-temperature side reaction tanks containing high-temperature hydrogen storage alloys,
In a heat-driven heat utilization device configured by connecting multiple low-temperature side reaction tanks containing a built-in low-temperature hydrogen storage alloy, refrigerant is supplied to the refrigeration load via the multiple low-temperature side reaction tanks when hydrogen transfer operation is switched. are doing.

(e) Function A certain amount of sensible heat is recovered in the reaction tank, and defrosting can be performed without a large amount of heat flowing into the refrigeration equipment at the time of switching, so the cooling efficiency of the refrigeration equipment is not reduced and the cooling efficiency is Can be defrosted.

(f) Embodiment FIG. 1 is a block diagram of the refrigeration system of the present invention. In the figure, (1) and (") are the high temperature side alloy tank containing the hydrogen storage alloy M1 for regeneration, and (2) ), (2°) are the low-temperature side alloy tanks containing the hydrogen storage alloy M2 for generating refrigeration heat, and the alloy tanks (IL(1'), (21, (2°)) are the open/close valves ■5 and V6. The high temperature heat source (5) in (4) is a low temperature heat source, and is connected through the heat medium circulation path provided with four-way valves V1 and 2. It is connected to the heat exchanger in the alloy tanks (1) and (1').In addition, (5°) is the low temperature heat source, (6) is the refrigeration load, and the heat source is equipped with four-way valves ■3 and V4. It is connected to the heat exchanger in the alloy tanks (2) and (2') through a medium circulation path.

The operation of the above-mentioned refrigeration system will be explained based on the pressure-temperature equilibrium diagram of the heat pump shown in FIG. The vertical axis of the figure shows the equilibrium pressure P of hydrogen on a logarithmic scale, and the horizontal axis shows the reciprocal value 1/T, where T is the absolute temperature. A is a pressure-temperature equilibrium diagram of hydrogen storage alloy M for regeneration, and B is a pressure-temperature equilibrium diagram of hydrogen storage alloy M2 for refrigeration heat generation.

In the initial state, the hydrogen storage alloy M2 for refrigerating heat generation is in a hydrogen absorption state, and the hydrogen storage alloy M1 for regeneration is in a hydrogen release state.

Now, when the on-off valves 5 and V6 between the alloy types are opened, hydrogen gas flows from the alloy tank (2) (or2°) to the alloy tank (1) (orlo) due to the pressure difference. At this time, according to equation (1), the hydrogen storage alloy M2 for refrigeration heat generation releases hydrogen and cools MH2 + heat 2M + Hz by an endothermic reaction.
(1) On the other hand, since the regenerating hydrogen storage alloy M absorbs hydrogen and generates heat, it is cooled via a heat exchanger.

(Cold heat generation process: A → mouth in Figure 2) When the movement of hydrogen gas is completed, the reaction stops.

Next, the heat medium circulation path is switched by valves V1 to 4, and heat is supplied from the heat source to the alloy tank (1) (orl') to cool the alloy tank (21 (or2')). Hydrogen is returned to (21 (or2')) by the reverse reaction (regeneration process: c→2 in Figure 2).

At this time, two sets of alloy tanks are prepared, and continuous operation can be performed by simultaneously performing the freezing heat generation process and the regeneration process by alternately switching the valves. - As an example, a pressure-temperature equilibrium diagram is shown in FIG. 3 when zirconium and rare metal alloys are used.

If we pay attention to the refrigerant temperature at the time of switching the operation, we can see that the temperature of the alloy tank (2
) or (2°) is 20 to 40°C, so the refrigerant at this temperature flows into the refrigeration load (6) side. And the alloy tank (2
) or (2゛), and the temperature gradually decreases, so the heat supplied to the refrigeration load (6) causes hunting every time it is switched, as shown by the solid line in Figure 4. Become. Assuming a fan-type refrigerator, defrosting is performed when refrigerant at 0° C. or higher is flowing through the heat exchanger on the refrigeration load side, so the fan is stopped at this time and no cold air is blown out. Then, when the temperature of the refrigerant flowing in the heat exchange air drops below a predetermined temperature, the fan is operated to perform cooling.

By the way, if you simply switch the heat medium when switching operations,
As described above, since the refrigerant at 20 to 40° C. (high temperature from the viewpoint of the refrigeration load) flows into the heat exchanger on the refrigeration load side, although defrosting is sufficiently performed, the refrigeration capacity tends to decrease.

Therefore, after the regeneration process is completed, by switching only the 4-way valve V4 on the outlet side of the cooling water and refrigeration load, the
A decrease in refrigeration capacity can be prevented by sending 0°C cooling water to the alloy tank that had been generating refrigeration heat until just before, and supplying the refrigerant, which has been cooled by the sensible heat of the alloy tank, to the refrigeration load. Then, due to the hydrogen absorption/desorption reaction, the alloy tank on the regeneration side becomes (1)
(1°) becomes above a predetermined temperature, or when the alloy tank (2) (2' l) on the refrigeration heat generation side becomes below a predetermined temperature, the cooling water and the 4-way pulp V on the return side of the refrigeration load are removed. , and return to normal operation. In this case as well, the O''C0 or higher medium flows into the refrigeration load (6) and is used for defrosting.

Another method is to close V6 after completion of regeneration to stop the movement of hydrogen and also stop the supply of refrigerant to the refrigeration load (6) side, and circulate the refrigerant between the alloy tank (2) and (2°). It is also possible to carry out normal operation after clear recovery. In this case as well, the refrigerant at 0° C. or higher flows into the refrigeration load (6) and defrosts it.

Method 1 is the conventional case where the valve switching time is simply changed, Method 2 is the case of the present invention example where the valve switching time is changed, and Method 3 is the case of the present invention example where sensible heat is recovered between the alloy tanks. Defrosting is performed using the refrigerant shown in FIG. 5, which has a temperature of 0° C. or higher.

Although this embodiment has been described only regarding defrosting of a refrigeration system, it can also be applied to other operation modes of a heat pump. For example, in the temperature increase mode, it is possible to use high temperature heat output during operation for heating, and use medium temperature heat output during switching for hot water supply, promoting effective use of heat.

(G) Effects of the Invention As described above, the refrigeration system of the present invention supplies refrigerant to the refrigeration load via a plurality of low-temperature side reaction tanks when switching operations for hydrogen transfer, so refrigerant can be removed without reducing cooling efficiency. Freezing can be done and efficient use of the refrigeration equipment can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a refrigeration system according to the present invention, FIG.
FIG. 3 is a pressure-isotherm diagram, and FIGS. 4 and 5 are characteristic diagrams showing heat output characteristics of refrigeration heat. <1) (1'l... hydrogen storage alloy tank for reheating, (2) <
2'1...Hydrogen storage alloy tank for freezing heat generation, (3) (3
°)...Hydrogen flow path, (4)...High temperature heat source, <51
(5')...Low temperature heat source, (6)...-Refrigerating load.

Claims (1)

[Claims] 1) Hydrogen transfer operation in a heat-driven refrigeration system configured by connecting multiple high-temperature side reaction vessels containing hydrogen storage alloys for high temperatures and multiple low-temperature side reaction vessels containing hydrogen storage alloys for low temperatures. A refrigeration system using a hydrogen storage alloy characterized by supplying refrigerant to a refrigeration load via a plurality of low-temperature side reaction tanks at the time of switching.