JPS6333064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat pump that contributes to the effective use of thermal energy, and relates to a heat pump that contributes to the effective use of thermal energy.
It is used in fields such as refrigeration.

Conventional configurations and their problems As conventional heat pumps, electric compression type and absorption type heat pumps have come into widespread use from the viewpoint of resource and energy conservation. However, problems remain with these as well, with electric compression heat pumps consuming a considerable amount of power, and it is desired to reduce the noise produced by compressor devices. On the other hand, absorption heat pumps require a small amount of auxiliary power to circulate the liquid or steam, and they also have drawbacks such as increased device size.

As a means of solving this problem, it is known to utilize a chemical heat pump that combines a solid or liquid absorbent material and a heat medium, such as water, and operates in a vacuum vessel in the absence of non-condensable gases. However, as already mentioned, completely exhausting gases other than the operating heat medium is an important factor for normal operation of this heat pump. The reason for this is that if the degree of vacuum decreases, the evaporation rate of the heating medium will drop extremely rapidly, and the absorption rate of the heating medium gas by the absorbent material will also drop.

However, gas other than the heating medium, such as air, adsorbed, absorbed, or dissolved in the absorbent material cannot be easily removed. Particularly when the absorbent material is solid, the adsorption surface area is large and complete evacuation is extremely difficult.

Purpose of the Invention The purpose of the present invention is to improve the characteristics of a chemical heat pump using an absorbent/thermal medium system, and in particular to clarify a manufacturing method that enables stable operation over a long period of time. This makes it possible to increase the amount of heat and the effective amount of heat.

Composition of the Invention The present invention allows non-condensable gases to be discharged as completely as possible, and is incorporated inside an absorbent material.
This is a means to more completely remove gases that may come out little by little over a long period of time, and first, the vapor pressure of the heat medium in the absorber increases as the absorption amount increases.
Therefore, in order to make the vapor pressure of the absorbent the lowest, the state after releasing the heat medium vapor, and
The pressure at this time is always lower than the vapor pressure of the liquid heat medium. Focusing on these facts, as a means to completely remove non-condensable gas adhering to the inner wall of the vacuum vessel and the absorbent material, we first use the absorbent material in the released state, which is the state with the lowest vapor pressure, to remove the non-condensable gas from the vacuum system. Vacuum the inside. More preferably, only the absorbent material in the released state shown above is placed in a container, and the vacuum is first evacuated, and then the heating medium having a relatively high vapor pressure is evacuated in another container, and the space between the two is evacuated. Open the valve to operate the heat pump.

Description of Examples Figure 1 is a schematic cross-sectional view of a chemical heat pump, in which 1 is 1 kg of synthetic zeolite, which is an absorbent.
It is a vacuum container with a built-in gas, and serves as both a generator and an absorber. 2 is water (200g) which is a heating medium.
It also serves as a condenser and evaporator for the 3 is a connecting pipe connecting both containers, 4 is a valve that can be opened and closed for water vapor circulation, and 5 is an exhaust port to create a vacuum inside these containers, and the final exhaust is completed. It will be sealed at this point.

We investigated the differences in the characteristics of chemical heat pumps depending on the order in which they are evacuated. First, in the apparatus shown in Fig. 1, 1 kg of dry zeolite is put into container 1, and without putting any water into container 2, the rotary pump is operated for about 30 minutes to exhaust the air through the exhaust port 5, and then the valve 4 Close. Next, 200 g of water was put into the container 2, and the air was again evacuated from the exhaust port 5 for 30 minutes, and then this exhaust port was sealed to provide a chemical heat pump A.

Further, the above operation was exactly the same, but when the container 1 containing the zeolite was evacuated, the zeolite was heated while being evacuated for 30 minutes to form a chemical heat pump B.

For comparison, as a conventional example, water was added to container 1.
Chemical heat pump C was created by adding 20% adsorbed zeolite and evacuating the entire system at the same time.
Furthermore, a prototype was made in which dry zeolite was put in container 1 and water was put in container 2, and the whole was evacuated at the same time, and this was designated as chemical heat pump D.

In order to obtain these properties, the conditions for the zeolite drying (regeneration) operation were as follows: heating container 1 to 120°C;
Container 2 was cooled to 25° C. and the drying time was 5 hours. In the reverse process, zeolite adsorption, in other words, water evaporation, container 1 was cooled to 40° C., container 2 was heated to 10° C., and the adsorption time was 5 hours. Such cycles were repeated and the amount of heat released from the container 1 during adsorption was determined for each cycle and divided by the total weight of the active substance to determine the heat storage density of the system.

Figure 2 shows how the heat storage density of each heat pump changes depending on the number of cycles. The symbols of broken lines in the figure correspond to the symbols of the heat pump described above. As is clear from this figure, heat pumps A and B according to the present invention have significantly less reduction in heat storage density than heat pumps C and D as conventional examples in which such considerations have not been taken. The cause of the deterioration of heat pumps C and D is that non-condensable gases such as air that are gradually released from the vacuum system accumulate, and the adsorption and desorption rates of zeolite and the evaporation and condensation rates of water are extremely reduced. I found out that this is what I did.

Of course, if you do at least one of the following: lengthen the desorption time, adsorption time, raise the desorption temperature, lower the adsorption temperature, lower the condensation temperature, or raise the evaporation temperature. Heat storage density is on the rise. However, in all cases, the effects of the present invention were evident to the extent shown in FIG.

In addition, the evacuation time was 30 in this example.
minutes, but even if this time was made longer than this, the degree of performance deterioration was almost the same in all cases.

Furthermore, heating the absorbent material during evacuation is an extremely effective way to remove more non-condensable gases that are absorbed inside the absorbent material and are difficult to remove by temporary evacuation. I understood.

In addition, absorbents other than zeolites, such as silica gel, calcium chloride, magnesium chloride,
The effects of the present invention were also observed with calcium oxide, magnesium oxide, etc., and were particularly noticeable in the case of solid absorbents.

Effects of the Invention The present invention makes it possible to obtain stable characteristics over a long period of time in a chemical heat pump using an absorbent/heat medium system, and facilitates the development of heat storage devices, cold storage devices, and heat pumps that can increase the amount of effective heat. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a chemical heat pump according to an embodiment of the present invention, and FIG. 2 is a diagram showing the characteristics of the chemical heat pump shown in FIG. 1. 1... Container (generator and absorber), 2... Container (evaporator and condenser).

Claims (1)

[Scope of Claims] 1. An airtight tank for an absorbent and an airtight tank for a heat medium are airtightly connected by a connecting pipe having a switch, and the absorbent is released into the airtight tank for the absorbent. After the switch is closed to prevent air from entering the airtight tank, a liquid heating medium is put in the airtight tank for heating medium, and only that airtight tank is evacuated. . A method for manufacturing a chemical heat pump, characterized in that the switch between the airtight tanks is then opened and put into operation. 2. The method for manufacturing a chemical heat pump according to claim 1, wherein the absorbent material is a porous solid. 3. A method for manufacturing a chemical heat pump according to claim 1 or 2, characterized in that the absorbent material is evacuated in a heated state.