JPH0472142B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a chemical heat pump device that utilizes heat generation and heat absorption in a reversible adsorption/desorption reaction of a working gas. It can be used to supply heating, hot water, or industrial heat.

Conventional configurations and their problems Heat pump devices can be roughly divided into three types: compression type, absorption type, and chemical heat pump. The chemical heat pump according to the present invention has been attracting increasing attention in recent years from the viewpoint of effective energy utilization.

Chemical heat pumps are heat pumps that utilize adsorption and desorption reactions of substances or phase change reactions, and the working medium is thought to be made of metal hydrides, inorganic hydrates, organic substances, zeolites, etc. These working gases include hydrogen,
Water vapor, ammonia, etc.

Next, the configuration of a conventional heat pump device and its problems will be explained using a metal hydride as an example.

A conventional general heat pump cycle exhibits the temperature/equilibrium pressure characteristics shown in FIG. Using two types of metal hydrides with different temperature and equilibrium pressure characteristics, we created a metal hydride (MH ₁ ) with a low equilibrium pressure at the same temperature.
When a substance that has sufficiently adsorbed hydrogen is heated at T _M degrees (state A) and communicated with a metal hydride (MH ₂ ) which has sufficiently desorbed hydrogen at T _L degrees and has a high equilibrium pressure at the same temperature, MH ₁ hydrogen moves to MH ₂ (state B). At this time, MH ₂ generates heat through an exothermic reaction, which is thrown away into the atmosphere. Next, _MH2 was heated at a temperature of T _M (state of C) to desorb hydrogen.
When communicating with MH ₁ , hydrogen from MH ₂ moves to MH ₁ . At this time, MH ₁ is warmed by the exothermic reaction and rises from T _M degrees to T _H degrees, generating heat at the equilibrium temperature of MH ₁ , which corresponds to the pressure close to the equilibrium pressure of MH ₂ at T _M degrees (state D). ).

By repeating the process A→B→C→D in this manner, high-temperature heat at a higher T _H temperature can be obtained from heat at a heat source temperature of T _M.

However, the temperature increase range obtained with this method is
The temperature range was almost fixed between T _M degrees and the heat radiation temperature T _L degrees, and no further temperature increase could be expected.

Purpose of the Invention The present invention effectively utilizes the temperature difference between the low-temperature heat source temperature and the heat radiation temperature, and uses an intermittent operation type 2 heat pump device that obtains heat output at a temperature higher than the heat source temperature, and generates heat output in one cycle. The purpose is to obtain a thermal output that increases the temperature to a temperature higher than the temperature increase range.

Structure of the Invention The present invention provides a multi-effect heat pump device having a working gas and a temperature at which the working gas can be reversibly adsorbed and desorbed.
This is a chemical heat pump device that stores two types of media with different equilibrium pressure characteristics in a sealed container divided into two rooms, and utilizes heat generation and heat absorption during adsorption and desorption reactions of gas, and the heat pump cycle consists of at least two sets. A second type heat pump cycle in which a low-temperature side adsorption-desorption reaction medium having the same temperature and high equilibrium pressure is heated by a heat source and adsorbed by a high-temperature side adsorption-desorption reaction medium having a low equilibrium pressure to obtain a temperature higher than the heat source temperature. The adsorption reaction exothermic temperature when the high-temperature side medium of the first cycle, which operates at a relatively low temperature, adsorbs the working gas, is set to the high-temperature side medium of the second cycle, which operates at a relatively high temperature. and the desorption reaction heating temperature of the low temperature side medium, and using the adsorption reaction heat of the first type 2 heat pump cycle, the second type 2 heat pump cycle is operated from the high temperature side medium. A two-stage (multi-stage) second stage that desorbs both the gas and the working gas from the low-temperature side medium, and radiates the heat generated on the low-temperature side of the first and second type 2 heat pump cycles at approximately the same temperature. This is a heat pump device.

In this case, the temperature equilibrium pressure characteristics of the adsorption/desorption medium on the low temperature side of the second heat pump cycle on the relatively high temperature side are set to be intermediate between the temperature and pressure characteristics of the two types of adsorption/desorption media in the first heat pump cycle on the relatively low temperature side. It is desirable to choose. Further, the present invention is characterized in that hydrogen gas is used as a working gas in at least one of each heat pump cycle, and a metal or an alloy thereof capable of forming a metal hydride is used as an adsorption/desorption reaction medium.

DESCRIPTION OF EMBODIMENTS FIG. 2 shows a configuration diagram of an embodiment of the multi-stage second type heat pump device of the present invention, and FIG. 3 shows a heat pump cycle diagram thereof. Note that the description will be made by taking a metal hydride as an example of a medium that can be adsorbed and desorbed.

As shown in FIG. 2, two sets of two types of metal hydrides having different temperature and equilibrium pressure characteristics were housed in two compartmented closed containers, respectively. Second
MH ₁ and MH ₂ in the figure form the first heat pump cycle that operates at a relatively low temperature, and MH ₃ and MH 2 form the first heat pump cycle that operates at a relatively low temperature.
A second heat pump cycle was configured to operate at a relatively high temperature with MH ₄ . In these two heat pump cycles, the high temperature heat generating side with lower equilibrium pressure at the same temperature is MH ₁ and MH ₃ .
It is.

Next, the operation of the heat pump device will be explained.

The metal hydride MH ₁ on the high temperature exothermic side of the first heat pump cycle is heated at T _M degrees by heat source 1,
When the metal hydride MH ₂ on the low-temperature exothermic side is cooled with outside air at T _L degrees and valve 2 is opened, the hydrogen adsorbed in MH ₁ moves to MH ₂ . At this time, MH ₁ causes an endotherm, while MH ₂ causes an exotherm. This heat is generated by radiator 3
Throw it away.

This operation causes hydrogen to move from state A to state B in FIG. After this, close valve 2 and heat source 1 to MH ₁ .
When heating from MH 2 is stopped and MH ₂ is heated by heat source 4 (T _M degrees), the equilibrium pressure rises to _PH . If you open valve 2 while continuing heating, hydrogen gas will be released.
Moving on to MH ₁ . At this time, an endotherm occurs in MH ₂ , and MH ₁
This produces a fever of T _H degrees. In this case T _H > T _M.

The heat radiation temperature on the low-temperature heat generation side of the second heat pump cycle is the same as that of the first, and is set to T _L degrees. The relative relationship on the temperature-pressure diagram of the two cycles is the fourth
As shown in the figure, there are countless possibilities, and (a) is MH ₁ .
The same material is used for MH ₄ so that the high pressure side is almost the same, and (b) the same material is used for MH ₂ and MH ₄ so that the low pressure side is almost the same. (c)ha
The temperature equilibrium pressure characteristics of MH ₄ are set between those of MH ₁ and MH ₂ , and both the high and low pressures in the first cycle are selected between the high and low pressures in the second cycle.

In any case, by setting the heating temperature T _M ′ of the second heat pump cycle to be slightly lower than T _H ,
The T _H degrees of heat generated by the first cycle drives the second cycle.

i.e. cooling _MH4 at T _L degrees, _MH3 and _MH4
When the valve 2' of the pipe communicating with is opened and the heat generated in MH ₁ is used to heat MH ₃ by the heat transport means 5,
Hydrogen in _MH3 moves to _MH4 .

When hydrogen transfers from MH ₃ to MH ₄ in this way, MH ₃ absorbs heat and MH ₄ generates heat.
The latter is discharged to the atmosphere by means of a heat sink 3'. The valve 2' is then closed and the MH ₄ is heated again by the heat source at T _H degrees generated by the first heat pump cycle, and the pressure increases to P _H '. If the valve 2' is opened here, hydrogen is adsorbed to MH ₃ and heat is generated at T _H ' degrees. By extracting this by the heat transport means 7, heat at a temperature T _H ' which is much higher than the heat source temperature T _M can be obtained. In reality, the heating of MH ₃ and the heating of MH ₄ are time-shifted, so two sets of the first cycle are prepared as shown in Figure 3, and the heat generated is used to heat MH ₃ and MH _4, respectively. It is best to operate them out of phase with each other. temperature difference
T _H ′−T _M is approximately 3 of the temperature difference T _H −T _M in the case of one stage.
You can get almost double the value. Note that the heat sources 1 and 4 may be the same.

As a specific example of the present invention, a heat pump device having a configuration as shown in FIGS. 2 and 3 and a temperature-pressure cycle was prototyped, and the results of its evaluation will be described.

T as MH _{1 i0.35} Z _r0.65 M _o1.2 C _r0.6 C _p0.2 T as MH _{2 i0.6} Z _r0.4 M _o1.4 C _r0.4 C _u0.2 MH _{3 i0.3} Z _r0.7
M _o1.2 C _r0.6 C _p0.2 MH ₄ as T _i0.45 Z _r0.55 M _o1.2 C _r0.6
Ti-Mn alloys of C _p0.2 are put into a device configured as shown in Figure 3: two sets of 5 kg each for the combination of MH ₁ and MH ₂ , and one set of 5 kg each for the combination of MH ₃ and MH ₄ . Filled. The metal hydride was adjusted so that approximately 31 moles of hydrogen gas were transferred in each cycle in the first heat pump cycle and 31 moles in the second heat pump cycle.

Assuming that the temperature of heat sources 1 and 4 was 72 degrees, and the heat radiation temperature by outside air was 30 degrees, an output temperature of 114 degrees was obtained from the first stage type 2 heat pump. Furthermore, the output temperature T _H ' of the second heat pump cycle heated by this heat source was 185 degrees.

Furthermore, the value obtained by dividing the amount of heat output by the input, the so-called coefficient of performance, was obtained as 0.09.

In principle, the product coefficients of each cycle are COP ₁ and COP ₂ , and the product coefficient of the two-stage cycle is
If CPO is ₀ , it is given by COP ₀ = COP ₁ × COP ₂ . Also, the product coefficient for each cycle is 0.5
not exceed.

MH ₄ to MH ₁ and MH ₂ as done in this experiment
It is preferable to select a material with pressure-temperature characteristics between . Further, it is preferable to use hydrogen gas as the working gas in at least one of each heat pump cycle, and to use a metal or an alloy thereof capable of forming a metal hydride as the adsorption/desorption reaction medium. Heat pump cycles using metal hydrides not only have excellent reversibility of the reaction and long life performance due to repeated operation, but also have the advantage of extremely fast reaction rates.

In addition, many of the materials for chemical heat pumps related to the present invention are capable of reacting at relatively high temperatures, and are not limited to two-stage heating by two heat pump cycles as shown in Examples, but also three-stage and four-stage heating. is also possible.

Heat pumps using metal hydrides use materials that are alloyed with hydrogen gas and have extremely high heat resistance, making them suitable for high-temperature heat pumps.
A single stage heat pump of the second type was only able to raise the temperature by the difference between the heat source temperature and the heat radiation temperature to the outside air (temperature of the heat sink).

Effects of the Invention The present invention makes it possible to raise the temperature by 2.5 to 3 times the difference between the heat source temperature and the heat radiation temperature to the outside air, etc.
It is possible to stack one or more layers using the same principle. In addition, by selecting the equilibrium temperature and pressure characteristics of the low-temperature side adsorption/desorption medium (MH ₄ ) in the second heat pump cycle to be intermediate between the two media in the first heat pump cycle, It is possible to select high pressure and low pressure to be within reasonable conditions for use, and it is easy to bring the coefficient of performance of the first cycle close to an ideal value.

[Brief explanation of the drawing]

Fig. 1 is a diagram of a one-stage type 2 heat pump cycle of a conventional embodiment, Fig. 2 is a block diagram of an intermittent operating multi-stage type 2 heat pump device of an embodiment of the present invention, and Fig. The heat pump cycle diagram of the heat pump device shown in the figure, FIGS. 4A to 4C are temperature-equilibrium pressure diagrams of typical examples of combinations of two-stage second type heat pump cycles, which are one embodiment of the present invention. 1, 4... Heat source, 2, 2'... Hydrogen gas valve, 3,
3'...Radiator, 5,7...Heat transport means.

Claims (1)

[Scope of Claims] 1. Two types of adsorption/desorption reaction media, which are substances capable of reversibly adsorbing and desorbing a working gas and have different temperature equilibrium pressure characteristics, are used, each of these media is housed in a container, and the working gas is At least two sets of chemical heat pump cycles are prepared that utilize exothermic heat absorption during transfer between media, and the low-temperature side adsorption/desorption reaction medium, which has the same temperature and high equilibrium pressure, is heated by a heat source, and the high-temperature side adsorption/desorption reaction medium has a low equilibrium pressure. It is used as a second type heat pump cycle (first cycle, second cycle) that obtains a temperature higher than the heat source temperature by adsorption to the medium, and the high temperature side medium of the first cycle operates at a relatively low temperature. The exothermic temperature of the adsorption reaction when adsorbing the working gas is set higher than the desorption reaction heating temperature of the high-temperature side medium and the low-temperature side medium of the second cycle, which operate at a relatively high temperature, and the adsorption reaction of the first cycle The second cycle is heated using the heat of reaction, and the first and second cycles are heated.
This is an intermittent-operating multi-stage second-class heat pump device that has almost the same heat radiation temperature on the low-temperature side of the cycle. 2. The intermittent operation type according to claim 1, wherein the temperature equilibrium pressure characteristics of the low temperature side adsorption/desorption medium in the second cycle are selected to be intermediate between the temperature equilibrium pressure characteristics of the two types of adsorption/desorption media in the first cycle. Multi-stage second class heat pump equipment. 3. The intermittent operating multi-stage second stage according to claim 1, wherein hydrogen gas is used as the working gas in at least one of each cycle, and a metal or its alloy capable of forming a metal hydride is used as the adsorption/desorption reaction medium. Seed heat pump equipment.