JPH06136357A - Production of chemical heat-storage material - Google Patents

Abstract

PURPOSE:To produce a chemical heat-storage material comprising an ammonia complex and having a controllable reaction temp. CONSTITUTION:An aq. soln. obtd. by completely dissolving CaCl2 and CaBr2 in water is concentrated and dried under heating and reduced pressure. To the resulting calcium salt mixture is added ammonia at about -20 deg.C under a pressure of ammonia gas of about 1.2atm to give a calcium salt mixture- ammonia complex, which is used as the chemical heat storage material.

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a chemical heat storage material. More specifically, the present invention relates to a method for producing an ammonia complex-based chemical heat storage material capable of controlling the reaction temperature.

[0002]

2. Description of the Related Art CaCl ₂ ·nNH ₃ (n=2, 4, 8) and CaBr ₂ ·nNH
Ammonia complexes such as ₃ (n = 2, 6, 8) are expected to be used as chemical heat storage materials such as heat storage and chemical heat pumps because the heat of reaction associated with the change in the number of ammonia additions is very large. It is

However, the reaction temperature at which the ammonia addition number of these chemical heat storage materials changes is governed by the type of chemical heat storage material, the partial pressure of ammonia gas in the atmosphere, and the like. There may be no chemical heat storage material with suitable reaction characteristics for operating temperature and pressure specifications.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an ammonia complex-based chemical heat storage material in which the reaction temperature can be controlled.

[0005]

DISCLOSURE OF THE INVENTION The object of the present invention is to:
This is achieved by adding ammonia to an anhydrous calcium salt mixture obtained by concentrating and drying an aqueous solution in which calcium chloride and calcium bromide are dissolved to produce a chemical heat storage material.

[0006] Calcium chloride, calcium bromide, both anhydrides and hydrates can be used. In the method of the present invention, first, predetermined amounts of calcium chloride and calcium bromide are completely dissolved in water, and then this aqueous solution is gradually heated and concentrated under reduced pressure to reprecipitate the dissolved calcium salt mixture. After the deposition residue is no longer moist, it is dried in a vacuum dryer at around 200°C for about 24 hours.

[0007] When ammonia is added to the resulting anhydrous calcium salt mixture under conditions of ammonia gas pressure of about 0.5 to 2 atm and temperature of about -30 to 20°C, CaCl ₂ and CaBr are produced at any mixing ratio. Calcium salt mixture ammonium complexes corresponding to the addition of _8NH3 to ₂ respectively were obtained.

[0008] The deNH ₃ temperature of the obtained calcium salt mixture ammonia complex also varies depending on the mixing ratio of the calcium salts.
In the case of the calcium salt mixture ammonia complex that was ammoniated under the condition of 20 °C, Ca
The _{highest deNH
3} Temperature (ammonia gas pressure 1 atm) is shown. (Blanks below) Table Mixing molar ratio De _{- NH3} weight in _8NH3 complex De _{- NH3} temperature _{CaCl2CaBr2NH3 addition} weight (%) (% by weight) ₍ °C) ) (8NH ₃ →4NH ₃ ) 90 10 53.2 27.1 34 80 20 51.3 26.3 36 70 30 50.0 26.0 38 60 40 48.1 23.8 39 50 50 46.5 21.1 40 40 60 45.1 17.2 39 30 70 43.9 14.1 37 20 80 42.6 12.1 34 10 90 41.5 10.5 32 0 100 40.5 10.1 26 (CaBr ₂ 8NH ₃ ) (8NH ₃ → 6NH ₃ ) Note) _NH3 addition weight in 8NH3 complex: _NH3 addition weight/ _8NH3 complex powder weight De _{- NH3} weight: Reaction _NH3 weight/ _8NH3 complex powder weight lost by DeNH3 temperature: reaction equilibrium temperature of _deNH3 reaction under _NH3 gas pressure of ₁ atm

In contrast, 70 mol % CaCl ₂ (anhydrous) and Ca
Br ₂ (anhydride) 30 mol % powdery calcium salt mixture was subjected to ammonia addition at an ammonia gas pressure of 1.2 atm and a temperature of -20°C. _DeNH3 at
When the temperature was measured, _NH3 from the reaction of _CaBr2.8NH3 → _{CaBr2.6NH3 + 2NH3} was _first released at 26°C, and then _CaCl2.8NH3 → _{CaCl2.4NH3 +} 4NH at ₃₀ °C. The reaction portion of ₃ NH ₃ was eliminated. That is, the reaction characteristics of the powder mixture added with ammonia are CaBr ₂ .8NH ₃ , CaCl ₂
・The reaction characteristics of _8NH3 are not different from those of each component alone.

[0010]

[Effect of the Invention] The reaction temperature at an ammonia gas pressure of ₁ atm is _CaCl2.8NH3 ⇔ _{CaCl2.4NH3 + 4NH3 30} °C _CaBr2.8NH3 ⇔ _{CaBr2.6NH3 + 2NH3} 27°C. On the other hand, the ammonia complex of the calcium chloride-calcium bromide mixture mixed through the aqueous solution state has a _deNH
It can be varied down to 0°C, making it possible to control the reaction temperature.

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[Written Amendment]

[Submission date] October 8, 1992

[Procedural amendment 1]

[Name of document to be amended] Description

[Correction target item name] 0003

[Correction method] Change

[Correction details]

[0003]However, the reaction temperature at which the number of additions of ammonia in these chemical heat storage materials changes is governed by the type of chemical heat storage material, the partial pressure of ammonia gas in the atmosphere, and the like. There may be no chemical heat storage material with suitable reaction characteristics for operating temperature and pressure specifications.

Claims (2)

[Claims] 1. A method for producing a chemical heat storage material, comprising adding ammonia to a calcium salt mixture anhydride obtained by concentrating and drying an aqueous solution in which calcium chloride and calcium bromide are dissolved. 2. A calcium salt mixture ammonia complex obtained by the method of claim 1.