JPH0238481A - Absorbent composition for absorption refrigerator - Google Patents

Abstract

PURPOSE:To obtain an absorbent which does not deteriorate even when subjected to high-temperature conditions for a long time and has excellent safety by simultaneously adding both a stabilizer effective for the refrigerant and a stabilizer effective for the absorbent to a specified absorbent. CONSTITUTION:A stabilizer for an absorbent comprising at least eight of a group 1 comprising at least one compound having at least one imino group and/or a group of formula II or/and a phenolic OH group in the molecule (e.g., phenothiazine) and a group 2 comprising at least one member selected from among a tribasic phosphite compound, a phosphate compound, an epoxy compound, a metal salt of a carboxylic acid and a basic lead salt (e.g., triethyl phosphite) and a stabilizer for a refrigerant comprising a five-membered or six-membered cyclic ether compound, an alcohol, a metal perchlorate, a nitro compound and an oxide are simultaneously added to an absorbent of a polyethylene glycol dialkyl ether of formula I (wherein R1 and R2 are each a 1-4C alkyl, and n is 2-20), e.g., polyethylene glycol dimethyl ether.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The absorbent composition (hereinafter referred to as composition) according to the present invention relates to an absorption refrigerant composition useful in absorption refrigerators and heat pumps.

[Prior Art] Generally, for example, an absorption refrigerator is a closed circuit system containing an absorption refrigerant composition as shown in FIG. 1, and is composed of a generator, a condenser, an evaporator, and an absorber. be done. In the evaporator,
By evaporating the liquefied refrigerant, it removes heat from the outside and freezes it. Furthermore, the refrigerant vapor vaporized in the evaporator is sent to the absorber, where it comes into contact with an absorption liquid with a low refrigerant concentration,
It is absorbed into this liquid.

The absorption liquid that has absorbed the refrigerant and has a high refrigerant concentration is sent to the generator. The inside of the generator is heated to, for example, about 100° C., and the absorption liquid with a high refrigerant concentration releases refrigerant vapor here. The refrigerant vapor released from the absorption liquid is
It is further sent to a condenser, where it is cooled to, for example, 60° C. or lower, condensed, and becomes a liquefied refrigerant. This liquefied refrigerant passes through the pressure reducing valve and is sent to the evaporator again, where it evaporates, removes heat from the outside, and freezes.

On the other hand, the absorption liquid that has released refrigerant vapor in the generator returns to the absorber as an absorption liquid with a low refrigerant concentration, contacts the refrigerant vapor again, and absorbs the refrigerant.

In this way, absorption chillers operate cycle processes continuously and over long periods of time, and as can be understood from the actions and conditions of each process, both the refrigerant and the absorption liquid are repeatedly heated and cooled. It is used under harsh conditions.

In other words, the biggest point to increase the efficiency of refrigerators is:
The objective is to make the refrigerant discharge temperature in the generator as high as possible and increase the amount of refrigerant discharged from the absorption liquid.

Therefore, there has been a strong demand for refrigerants and absorption liquids that are highly safe and do not deteriorate even under high-temperature conditions for long periods of time.

[Problems to be Solved by the Invention] In general, the following mechanism has been proposed as a mechanism for thermal deterioration of refrigerants, particularly fluorinated hydrocarbons, and absorbents, particularly polyethylene glycol dialkyl ether.

(1) Deterioration of fluorinated hydrocarbons (for example, in the case of monochlorodifluoromethane and tetrafluoroethane) When heated in the generator, due to the influence of (for example, Fe2O, etc.) formed on the surface of the metal material, Fluorinated hydrocarbons degrade and form metal halides (e.g. Fe2CD,3,F
e F3), produces hydrogen chloride or hydrogen fluoride.

For example, such deterioration of fluorinated hydrocarbons not only causes a decrease in refrigerant capacity, but also causes corrosion of the metal materials of the device due to the influence of the deterioration products.

Furthermore, the absorbent also deteriorates due to the influence of the deterioration products, resulting in a decrease in absorption capacity.

(For example, in the case of tetraethylene glycol dimethyl ether) Tetraethylene glycol dimethyl ether decomposes and deteriorates under the influence of metal halides (for example, FeCQ3, FeF,), hydrogen chloride, and hydrogen fluoride, producing aldehydes and acids. For example, the following reactions can be considered.

・CH, O (C, H4O), CH.

Furthermore, → CH, CHO + CH, COOH + (etc,) All of these degradation products of tetraethylene glycol dimethyl ether are poor in the dissolution knob of fluorinated hydrocarbons, so when tetraethylene glycol dimethyl ether deteriorates, it maintains its original refrigerating ability. I can't.

As can be seen from the mechanism of decomposition and deterioration described above,
The stability of the composition for absorption refrigerators based on the combination of fluorinated hydrocarbon and polyethylene glycol dialkyl ether is as follows:
It is based on the stability of both the refrigerant and the absorbent.

Therefore, judging from the mechanism of each decomposition and deterioration,
It goes without saying that it is important to select a rational stabilizer to inhibit decomposition, but it is also important to use stabilizers that are effective in inhibiting the decomposition of both the refrigerant and the absorbent.

On the other hand, as a combination of a refrigerant and an absorbent as a conventional absorption refrigerant composition, for example, Japanese Patent Application Laid-Open No. 60-4O185,
JP-A-60-4O186 and JP-A-60-4O
No. 187 discloses fluorinated hydrocarbons as refrigerants, polyethylene glycol dimethyl ether as absorbents, especially diethylene glycol dimethyl ether, l.
Diethylene glycol dimethyl ether or tetraethylene glycol dimethyl ether is disclosed.

Furthermore, JP-A-57-124664, JP-A-5
No. 8-61171, JP-A-58-201878, and JP-A-60-108490 describe the stability of absorption refrigerant compositions using fluorinated hydrocarbons as refrigerants and polyethylene glycol dimethyl ether as absorbents. A stabilizer for application is disclosed.

For example, JP-A-57-124664 discloses a stabilizer consisting of at least one member selected from the group consisting of phosphites, epoxy compounds, and organic tin compounds.

Furthermore, for example, according to Japanese Patent Application Laid-Open No. 58-61171,
Phosphate compounds are disclosed as stabilizers for absorption refrigerant compositions consisting of fluorinated hydrocarbons and polyethylene glycol dimethyl ether.

Further, for example, according to JP-A No. 58-201.878, the stabilizer is selected from the group consisting of carboxylic acid metal salts and basic salts, and furthermore, basic phosphites and epoxy compounds. Those selected from the group are disclosed.

Further, for example, JP-A-60-108490 discloses phosphorous esters as stabilizers.

However, although compositions for absorption refrigerators that use fluorinated hydrocarbons and polyethylene glycol cyakyl ether as refrigerants and absorbents, respectively, have superior physicochemical properties compared to other compositions, At present, no material with sufficient thermal stability has yet appeared.

[Means for Solving the Problems] When the present invention is used in absorption refrigerators and heat pumps, there is no thermal history, no decomposition deterioration due to acidic substances, no corrosiveness to equipment materials, and furthermore, there is no mutual interaction between refrigerant and absorbent. The object of the present invention is to provide an absorbent composition for an absorption refrigerator that has good solubility, does not precipitate crystals, and has high high temperature stability sufficient to exert the maximum capacity of the device.

The compositions related to the present invention include the following (A), (B) and (C).
It consists of

(A) ・ Absorbent chemical formula R8○(C2H,O)n R21(R1, R2・
an alkyl group having 1 to 4 carbon atoms, n: an integer of 2 to 20), i.e., ・CH,O(C,H4O)nCH3・CH,○(C2
H4O)nC2H1 ・CH,0(C2H4O) n C2H? -CH,○(
C,H,○)nC4Hs -C2H,○(C2H4O) n C2Ha・C,H6
0(C,H,0)nC3H? -C2H,O(C,H4O
) n C4Hs-C,H,○(C2H4O)nC3H
+-C3H,○(C2H,0)n C41-1°・C4
H,○(C2H4O)n C,H.

It is a single homolog or a mixture of two or more homologs of the homolog compound represented by.

Of course, the composition of each compound within a single homolog is not limited.

Particularly preferred is CJ(,0(C2H4O)nC[
(.

It is polyethylene glycol dimethether represented by

These polyethylene glycol dialkyl ethers can account for about 70 to 99.7 (wt.%) of the composition, but are particularly preferably about 85 to 98.9 (wt.%).

(B): Stabilizer for absorbent A stabilizer for increasing the thermal stability of absorbent (polyethylene glycol dialkyl ether), classified into the following two groups (li of each group (single or mixed).

1st group NH- group, or (and) -C-S- group, or (and)
One type of compound, or a mixture of two or more types, of compounds having at least one phenolic compound in the molecule.

Group 2 Two groups represented by one or a mixture of two or more of tribasic phosphite compounds, phosphate compounds, epoxy compounds, carboxylic acid metal salts, and basic lead salts, either alone or in combination.

Examples of compounds belonging to the first group include: -phenothiazine and its derivatives -2,6-t-butyl-4-methylphenol -2,2'-methylenebis(6-tert-butyl-
4-methylphenol) ・4,4゛-butylidenebis(6-tert-butyl-m-cresol) ・1,1-bis-(4-hydroxy-phenol)cyclohexane ・Styrenated phenol ・4,4°-thiobis( 6-tert-butyl-3-
methylphenol) ・Dilauryl-3,3”-thiodipropionate ・2-
Mercapto-benzimidazole nickel dibutyl dithiocarbamate/N,N'-dise-butyl-P-phenylenediamine/diphenylguanidine/P,P"-dioctyldiphenylamine/nonyldiphenylamine/N-1,3-dimethylbutyl-N"-phenyl P-phenylenediamine/N-isopropyl-N-phenyl-P-phenylenediamine/N,N'-diphenyl-P-phenylenediamine/N
, No-diallyl-P-phenylenediamine/6-nitoxy 2.2.4-1-listyl-1,2 dihydroquinoline and polymer/phenothiazine Particularly preferred compounds include the following compounds.

・Phenothiazine ・N-isopropyl-N-phenyl-P-phenylenediamine ・N,N'-diphenyl-P-phenylenediamine ・
N-1,3-dimethylbutyl-No-phenyl P-phenylenediamine/N, N'-diallyl-P-phenylenediamine/N,
Examples of compounds belonging to the N"-dise-butyl-P-phenylenediamine group include the following compounds.

・Tribasic phosphite compound Chemical formula %formula% [However, R,, R2, and R3 are each independently an alkyl group.

A compound represented by an alkenyl group, an aryl group, or an aralkyl group.

Examples include triethyl phosphite, tributyl phosphite, tristearyl phosphite, tridecyl phosphite, trilauryl phosphite, triphenyl phosphite, and the like.

・Phosphate compound chemical formula % Formula % [However, R, , R2, R3 are each independently an alkyl group,
Indicates an alkenyl group and a phenyl group. For example, trioctyl phosphate, tributyl phosphate, diethyl phosphate, diisopropyl phosphate.

・Epoxy compound ■ Epoxidized fatty acid ester For example, methyl epoxy stearate, octyl epoxy stearate, butyl epoxy stearate, cyclohexyl epoxy stearate, benzyl epoxy stearate, hexyl epoxy stearate ■ Epoxidized oil For example, epoxidized soybean oil, Epoxidized linseed oil, epoxidized cottonseed oil Glycidyl ether For example, phenyl glycidyl ether, alkylphenyl glycidyl ether Epichlorohydrin Bisphenol condensate/carboxylic acid metal salt For example, stearic acid, lauric acid, or ricinoleic acid metal (K, Na, Ca, Ba, □Zn, Cd, Sn,
Sr, Pb, etc.) salts.

・Basic lead salts such as basic lead carbonate [2PbCO, .pb(○H)2
], basic lead sulfate [3Pb○・pbso,・I-I 2
0, basic surface lead phosphate [2PbO-PbHPO3・1
/2H20co, dibasic lead phthalate [2PbO-Pb(
C8H4O4)] Compounds belonging to these two groups can be used alone or in a mixture of two or more.

In addition, these stabilizers may be present in the composition in an amount of about 0.05 to 10 (
% by weight), but more preferably about 0
．． 1 to 5 (wt%).

(C): Refrigerant stabilizer The following compound is a stabilizer for increasing the thermal stability of refrigerants (fluorinated hydrocarbon refrigerants) and further enhancing the corrosion prevention effect. 5-membered or 6-membered cyclic ether compounds, alcohols, overbased metal salts, nitro compounds, and oxides alone or in mixtures of two or more. Specifically, the following compounds can be mentioned.

- 5-membered ring or 6-membered ring cyclic ether compound, for example, 1,
4-diosan, 1,3-diosan, 4-methyl-1,3
-diosan, 2,4-dimethyl 1,3-dioxane, 1
．． 3-dioxolane, 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, alcohols such as methanol, ethanol, propatool, butanol, octatool, acetylene alcohol/overbased metal salts For example, calcium carboxylate, calcium sulfonate, calcium finate salicylate, calcium sulfonate, barium carboxylate, barium sulfonate, barium finate salicylate, barium sulfonate, magnesium carboxylate,
Magnesium sulfonate, magnesium finate salicylate, magnesium phosphonate nitro compounds such as nitromethane, nitroethane, nitropropane,
Nitrobenzene oxides such as ethylene oxide, propylene oxide,
Butylene oxide A stabilizer (C
) can be used as These stabilizers can account for about 0.2 to 20 (wt%) of the composition, more preferably about 1 to 10 (wt%).

Examples of refrigerants used in absorption refrigerators or heat pumps using the composition of the present invention include: monochlorodifluoromethane, dichloromonofluoromethane, trifluoromethane, monochlorotrifluoromethane, difluoromethane, tetrafluoromethane, monochlorotetrafluoromethane - So-called fluorinated hydrocarbon compounds such as monochlorodifluoromethane and dichlorotrifluoromethane can be used alone or in mixtures, which can be selected as a refrigerant depending on the operating conditions of the absorption cycle. Generally, about 5 to 70 parts of refrigerant is added to 100 parts of the composition of the present invention.
A refrigerant/absorbent composition for an absorption refrigerator can be constructed by using the above.

[Example] Next, the present invention will be explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Refrigerant (e.g. monochlorodifluoromethane) and absorbent (e.g. polyethylene glycol dimethyl ether)
In order to evaluate the effects of various stabilizers (B and C) on the following compositions for absorption refrigerators were prepared.

Composition for evaluation (parts by weight) Monochlorodifluoromethane, 30 (or tetrafluoroethane) - Polyethylene glycol dimethyl ether - Stabilizer (B) 2.0 - Stabilizer (C
) 3.0 This evaluation composition was placed in a stainless steel (SUS-316L) autoclave, and iron pieces, copper pieces, and aluminum pieces were also placed there.
The stability of the refrigerant and absorbent was tested after a 30-day heating test at 00'C ± 5°C.

■ Stability of refrigerant (a) In the case of monochlorodifluoromethane: Measure the amount of chlorine ions ((1)) in the composition after the test.

(b) In the case of tetrafluoroethane, measure the amount of fluorine ions (F-) after the test.

■Absorbent stability: The composition of the absorbent after the heating test was analyzed using gas chromatography, and the amount of decomposition products was measured.

■Effect on metal pieces: Visually observe metal pieces after heating test.

The composition of the polyethylene glycol dimethyl ether [OH, (C, H, O) nCH,] used in the test was as follows.

n Molecular homolog (wt%) 2 ・・・・・・ ・・・・・・・・・・・・・・・・・・
・ ・・・・・・ 0.63 ・・・・・・・・・
・・・・・・・・・・・・・・・・・・ 19.04
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・ 29.05 ・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・ 24.16 ・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・ 15.07 ・・・・・・・・・・・・・・・
−・・・・・・・・・・・・・・・ 8.08 ・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・ 3.69 ・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・ 0.7 again,
"Stability test results" are shown in Table 1.

[Effect of the invention] As is clear from the results of Examples and Comparative Examples in Table 1,
It has been found that the stabilizers (B and C) according to the invention have a significant effect as stabilizers for refrigerants and absorbents.

This figure conceptually shows the outline of the flow of refrigerant and absorption liquid in an absorption refrigerator and a heat pump.

Claims (1)

[Scope of Claims] A refrigerant absorbent composition for an absorption refrigerator, comprising an absorbent A and stabilizers B and C shown below. A: Absorbent polyethylene glycol dialkyl ether represented by the general formula R_1O(C_2H_4O)nR_2. [However, R_1 and R_2 are alkyl groups having 1 to 4 carbon atoms, n
is a positive number from 2 to 20] B: Absorbent stabilizer 1st group: -NH- group, or (and) ▲There are mathematical formulas, chemical formulas, tables, etc.▼, or (and) phenolic OH in the molecule One type of compound having at least one compound, or a mixture of two or more types. Second group: Two groups represented by one or a mixture of two or more of tribasic phosphite compounds, phosphate compounds, epoxy compounds, carboxylic acid metal salts, and basic lead salts, either alone or in combination. C: Refrigerant stabilizer A 5- or 6-membered cyclic ether compound, alcohol, overbased metal salt, nitro compound, and oxide, either alone or in a mixture of two or more.