JPH0252786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a chemical heat pump that can be used in fields that require air-conditioning or air-conditioning functions, ranging from large factories and large buildings to small recreational equipment. It is related to.

Conventional configuration and its problems Chemical heat pumps that use water as a refrigerant have been researched and developed more than ever before. In particular, many types of absorbent materials (hereinafter "absorbent" is interpreted as including adsorbent materials) have been developed.
Representative examples include sodium sulfide (5←→water salt) and zeolite. All of these have advantages and disadvantages. First, sodium sulfide can provide high temperatures by using the absorbed heat for heating, but the heat of condensation can only provide low temperatures. Therefore, the practical product coefficient (COP
= Available heat amount ÷ Heat amount obtained from the heat source) is less than 1 even when loss is not considered. Furthermore, sodium sulfide exhibits strong alkalinity, and metals,
Since it corrodes glass and the like, it is necessary to use expensive materials for the device, and it is also toxic to the human body, making it difficult to use. Zeolite has a high ability to absorb water vapor, making it advantageous when used for air conditioning. On the other hand, when regenerating zeolite that has once absorbed water vapor, high-temperature heat is required due to its large absorption capacity.For example, when regenerating using solar energy, an expensive high-efficiency collector must be used, or else If this happens, regeneration will be performed with extremely low efficiency.
Moreover, since zeolite does not have selectivity in absorbing gas, it is easily deactivated by impurity gas. In addition, zeolite itself is expensive, and since it is a porous solid, it has poor thermal conductivity and requires internal fins to compensate for heat transfer inside the zeolite tank. system is difficult. Regarding calcium chloride, chemical heat pumps that utilize the absorption equilibrium between dihydrate and monohydrate have been reported. The advantages of this system are many. First, calcium oxide is a commonly used drying material, and is inexpensive and easily available. It is also non-toxic, easy to handle, and does not require expensive equipment. Furthermore, it selectively absorbs water vapor and does not require consideration for small amounts of impurity gas.

However, it has been found that when a calcium chloride-water based chemical heat pump is operated for a long period of time, its performance gradually deteriorates and the metal container is corroded. The cause of this is thought to be that calcium chloride partially decomposes under high temperature and vacuum conditions, producing chlorine gas, which deteriorates the degree of vacuum, reducing operating performance and corroding the metal container. .

Purpose of the invention The purpose of the present invention is to provide a highly reliable, long-life, inexpensive, and highly efficient chemical heat pump that takes advantage of the advantages of calcium chloride and suppresses the deterioration of performance during long-term operation, which has been a drawback. shall be.

Structure of the Invention The present invention connects two sealed tanks with a connecting pipe provided with bulbs, one contains an absorbent material that reversibly absorbs and releases heat medium vapor, and the other contains a heat medium liquid. The chemical heat pump is characterized in that calcium chloride is used as the heating medium, water is used as the heating medium, and at least one of calcium hydroxide and calcium oxide is added to the calcium chloride.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The device has two tanks A and B connected by a connecting pipe 5 provided with a valve 1, with tank A containing water 2 and tank B containing absorbent 3. Both tanks A and B are internally equipped with heat exchangers 4a and 4b, allowing for easy input and output of thermal energy. Also,
After degassing, the device remains airtight and no gas other than water vapor is present inside. The maximum amount of water contained in calcium chloride during absorption and desorption is determined by the sum of the amount of water initially put into tank A and the amount of water initially contained in calcium chloride in tank B. be done.

The operating method of the device is a so-called batch type, and one cycle consists of two steps: a heat storage step and a heat radiation step.
The heat storage process is a process in which tank B is heated by obtaining heat from a heat source, hot steam is released from tank B, is condensed in tank A, and heat is output from tank A. At this time, tank A is a condenser, Tank B acts as a regenerator. After this process, the absorbent in tank B is in a high energy state, and if valve 1 is closed at this time, the energy is conserved. The heat dissipation process is a process in which the regenerated absorbent absorbs the water stored in tank A as water vapor and takes away the latent heat of vaporization from tank A. At this time, tank A is the evaporator, tank B
The tank acts as an absorber. The heat dissipation process can be used in two ways: for cooling and for heating. When used for air conditioning, if tank B is cooled to around room temperature, tank A will emit steam at a lower temperature than room temperature, so cooling can be performed. When used for heating, if tank A is heated near room temperature, tank B will emit absorbed heat at a higher temperature than room temperature, resulting in a heating effect.

When calcium chloride is used as an absorbent material in such a chemical heat pump, as mentioned above, it has the disadvantage that it decomposes at high temperatures and under vacuum, albeit very slowly. The present invention provides a solution to this problem by using calcium hydroxide or calcium oxide as an additive. In other words, calcium hydroxide absorbs chlorine gas,
It is presumed that the deterioration of the vacuum inside the heat pump was suppressed by turning into calcium chloride and water. Also,
Since chlorine gas is absorbed, corrosion of the metal materials of the vacuum container is also suppressed.

Next, a more specific explanation will be given. A chemical heat pump was formed using a container configured as shown in FIG. 1, a stop valve 1, and a connecting pipe 5. That is, nothing was put in tank A, but 220 g (1 mol) of calcium chloride hexahydrate and a small amount of calcium hydroxide as an additive were put in tank B. A large number of chemical heat pumps, which were identical except for the weight proportions of the additives, were constructed and assembled by evacuating the inside of each container.

First, the temperature of tank B was maintained at 80°C for 2 hours to perform a heat storage process, and then tank A was maintained at 30°C, and the amount of heat that could be taken out from tank B, that is, the amount of heat storage that could be obtained at a temperature of 40°C or higher was determined. . This cycle was repeated for the chemical heat pump containing the additives in the above-mentioned amounts, and the amount of heat stored after 100 cycles was determined, and the results are summarized and shown in FIG. Calcium hydroxide, which is an additive, will not be dehydrated and become an oxide under the conditions of the heat storage process described above,
Also, since it does not absorb water vapor, it does not have the heat storage effect as a chemical heat pump. In this sense, it is not preferable to add too many additives because it increases the size and weight of the device.
However, as is clear from Figure 2, the effect was small below 0.1% (weight ratio). The reason for this is presumed to be that the absorption rate of the generated chlorine gas is too low in the case of a small amount of additive.

In order to investigate the optimal range of addition amount in more detail, the above cycle conditions were changed, the number of cycles was further increased, and the characteristics were determined up to about 1000 cycles. As a result, 0.1%, almost the same as in Figure 2.
The above was necessary. Although there is no clear maximum value, a value of about 5% or less is preferable in order to suppress weight increase.

In the above examples, calcium hydroxide was used as an additive, but similar effects were also observed with calcium oxide. This is easily converted to calcium hydroxide by the water contained in calcium chloride, and then it does not return to calcium oxide under normal heat storage conditions, but always remains as calcium hydroxide. Therefore, it is natural that exactly the same effect occurred. Although there was a tendency for the addition ratio to be slightly smaller than in the case of calcium hydroxide, it was found that the optimum addition amount may be approximately the same as in the case of calcium hydroxide.

Effects of the Invention As described above, according to the present invention, calcium chloride
This makes it possible to operate a water-based chemical heat pump stably over a long period of time, and to produce a long-life heat storage device and effective heat amount increasing device.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of a chemical heat pump according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram showing the performance of the chemical heat pump of FIG. 1. 1...Valve, 2...Water, 3...Absorbent, 5...
...Connecting pipe, A, B...tank.

Claims (1)

[Scope of Claims] 1. Two sealed tanks are connected by a connecting pipe provided with a valve, one is filled with an absorbent material that reversibly absorbs and releases heat medium vapor, the other is filled with a heat medium liquid, and the above-mentioned absorption A chemical heat pump characterized in that calcium chloride is used as a material, water is used as the heating medium, and at least one of calcium hydroxide and calcium oxide is added to the calcium chloride. 2. The chemical heat pump according to claim 1, wherein the addition ratio of at least one of calcium hydroxide and calcium oxide is within a weight range of 0.1 to 5% relative to calcium chloride.