JPH0126470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a chemical heat pump that aims to effectively utilize thermal energy and is used in fields such as air conditioning, heat storage, and 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 these problems, 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 reduced pressure 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, gases 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 present invention provides a manufacturing method that improves the characteristics of an absorbent-thermal medium type chemical heat pump, and in particular enables stable operation over a long period of time, thereby improving heat storage,
This makes it possible to store cold heat and increase the amount of effective heat.

Structure of the invention To exhaust non-condensable gas as much as possible more completely,
Moreover, it is a method that completely removes gases that are inside the absorbent material or inside the heat transfer liquid and may come out little by little over a long period of time.

Focusing on the fact that the vapor pressure of the heat transfer liquid is always higher than the vapor pressure of the heat transfer medium absorbed by the absorber when both are at the same temperature, it is possible to cool the heat transfer liquid and lower this vapor pressure. It can be seen that by reducing the vacuum to a vacuum, the entire system can be evacuated more completely. In the present invention, in order to further completely exhaust the air, the heat transfer liquid is frozen and then evacuated, or the gas dissolved in the liquid is evacuated once it is in a cooled liquid state, and then the liquid is frozen and the vacuum is drawn again. .

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 is a container containing a gas, and serves as both a condenser and an evaporator. 3 is a connecting pipe that connects both containers, 4 is a valve that can be opened and closed for water vapor circulation, and 5 is an exhaust port for evacuating the entire container, which is closed after the final exhaust is completed. do.

We investigated the differences in the characteristics of chemical heat pumps depending on the order in which they are evacuated. First, evaporator 2
A is a chemical heat pump that has been cooled down to ℃ and then evacuated for about 10 minutes using an oil rotary vacuum pump. B. Further, a chemical heat pump C was constructed by first cooling the evaporator to 2°C and preliminarily evacuation for 2 minutes, then lowering the temperature of the evaporator to -5°C, and evacuation was performed again for 10 minutes. For comparison, a chemical heat pump manufactured using a conventional construction method, that is, vacuuming was performed for about 10 minutes while the evaporator was kept at room temperature, was designated as D. In both cases, the absorber 1 was evacuated at room temperature.

Next, in order to determine the characteristics of these chemical heat pumps, when drying (regenerating) zeolite,
Container 1 was cooled to 120°C and container 2 was cooled to 35°C for 5 hours. In addition, during the reverse process of zeolite adsorption, container 1 is cooled to 40℃, container 2 is
was heated to 10°C, and the adsorption time was 5 hours. Such cycles were repeated, and the amount of stored heat released from the container 1 during adsorption was determined for each cycle. As a result, the initial cycle characteristics did not change much and each heat pump showed almost the same values. However, as shown in Figure 2, the performance of chemical heat pump D (curve D), which is a conventional example, gradually decreased with each cycle, whereas chemical heat pump A showed some deterioration, but heat pump D
The deterioration is considerably smaller than that of heat pumps B and C, and the effect is particularly remarkable in the case of heat pumps B and C. The cause of this is, as already indicated, that the deterioration of the degree of vacuum within the vacuum system is small, and this is due to the state within the evaporator during evacuation. That is, the process according to the invention allows the vacuum system to be evacuated more completely;
It was found that the long-term release of non-condensable gas into the vacuum system was suppressed, and the adsorption/desorption rate of zeolite and the evaporation rate and condensation rate of water were extremely reduced.

Of course, if you do at least one thing, such as lengthen the desorption/adsorption time, raise the desorption temperature, lower the adsorption temperature, lower the condensation temperature, or raise the evaporation temperature, The heat storage density tends to increase. However, the effects of the present invention were noticeable in all cases to the extent shown in FIG.

Further, in each of the examples, the operating time of the oil rotary vacuum pump was set to 20 minutes, but even if the operating time was longer than this, the performance was almost the same.

Further, in this example, water was used as the heating medium and zeolite was used as the absorbent, but the effects of the present invention were also noticeable with other heating mediums such as methanol, ethanol, ammonia, and fluorocarbons. The effect was similarly great with other absorbent materials that absorb and release reversibly.

Effects of the Invention The present invention makes it possible to obtain stable characteristics over a long period of time in an absorbent-heat medium system chemical heat pump, and to increase the effective heat amount of a heat storage device, a cold heat storage device, or a heat storage device.

[Brief explanation of drawings]

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 of FIG. 1. 1... Container (generator and absorber), 2... Container (evaporator and condenser).

Claims (1)

[Scope of Claims] 1. A method for exhausting a heat medium of a chemical heat pump, characterized in that the heat medium reversibly absorbed and released by an absorbing material is evacuated in a frozen state. 2. A method for evacuating a heat medium of a chemical heat pump according to claim 1, characterized in that the heat medium is preliminary evacuated in a cooled state, and then the heat medium is evacuated in a frozen state.