CA2210902A1 - Use as cold transfer media of aqueous solutions of lower alcohols - Google Patents
Use as cold transfer media of aqueous solutions of lower alcoholsInfo
- Publication number
- CA2210902A1 CA2210902A1 CA002210902A CA2210902A CA2210902A1 CA 2210902 A1 CA2210902 A1 CA 2210902A1 CA 002210902 A CA002210902 A CA 002210902A CA 2210902 A CA2210902 A CA 2210902A CA 2210902 A1 CA2210902 A1 CA 2210902A1
- Authority
- CA
- Canada
- Prior art keywords
- transfer medium
- cold transfer
- additive
- acid
- substances
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
- C09K5/08—Materials not undergoing a change of physical state when used
- C09K5/10—Liquid materials
Abstract
Disclosed is a cold transfer medium for use in a refrigeration system having separate circuits for a refrigerant and the cold transfer medium. The cold transfer medium is an aqueous solution of a lower alcohol with the addition of (1) a low molecular weight polycarboxylic acid, (2) an ester or salt of sorbic acid, (3) a polyhydric alcohol, (4) an aliphatic acid or a salt of an aliphatic acid, (5) an anionic surfactant and/or (6) a sulfur-free triazole compound. Also disclosed is such an aqueous solution containing finely divided silica as a sedimentation inhibitor.
Description
USE AS. COLD.TRANSFER MEDIA OF AQUEOUS
SOLUTIONS OF LOWER kLCOHOLS
The invention relates to a cold transfer medium consisting essentially of an aqueous solution of a lower alcohol containing a property-improving additive which may be a single substance or a combination of substances of two to six different classes of substances or containing finely divided silica as a sedimentation inhibitor.
Chlorofluorocarbons (CFCs) such as difluorodichloro-methane and trifluorochloromethane were previously widely usedas refrigerants, but have fallen into disrepute after it became known that they contribute to the destruction of the ozone layer around the earth and to the so-called greenhouse effect. The engineering measures which seek to reduce the amounts of CFCs, hydrochlorofluorocarbons (H-CFCs) or fluoro-carbons (FCs) required for a particular cooling performance include the separation of a refrigeration system into a refrigerant circuit and a circuit containing a cold transfer medium. In the first-mentioned circuit, the temperature of the refrigerant is still reduced by partial evaporation and indirect heat exchange takes place between the refrigerant and the cold transfer medium which circulates in the second circuit and provides its cooling effect at the desired location by taking up heat. For economic reasons, particularly in relatively large facilities such as air-conditioned buildings, supermarkets having a plurality of refrigerated or freezer chests or cool stores, this principle of separating O.Z. 5072 the refrigerant circuit and the circuit containing the cold transfer medium is also employed when one of the refrigerants mentioned are used.
Coolants based on ethylene or propylene glycol are at present widely used as a cold transfer medium. Although these coolants have a high specific heat and therefore a corresponding cooling performance, they display a temperature behaviour directly dependent on the cooling performance. For this reason, increasing use is being made more recently of a so-called liquid ice mixture comprising a water-soluble alcohol, generally ethanol, and water as a cold transfer medium which has a favourable heat transfer behaviour. This mixture is cooled in an ice generator specifically constructed for this purpose until part Gf the water freezes out in the form of fine ice crystals. A heat exchange surface is kept free mechanically so that growth of the ice crystals deposited there is prevented. The resulting two-phase system, also knGwn as liquid ice, is conveyed in a closed circuit and is readily pumpable. The mean particle diameter of the ice crystals in the liquid ice is about 100 ~m in the system based on ethanol/water which is customary nowadays. A particular problem in the liquid ice system is the deposition of an organic slime on the heat exchange surface and/or in pipes, which reduces heat exchange, increases the pressure drop in the system and makes frequent cleaning necessary.
It has now been found that the aqueous solution of a lower alcohol with an addition of (1) a low molecular weight polycarboxylic acid, (2) an ester or salt of sorbic acid, (3) a polyhydric alcohol, (4) an aliphatic acid or a salt of an aliphatic acid, (5) an anionic surfactant and/or (6) a sulfur-free triazole compound can be advantageously used as a cold transfer medium.
The additive employed according'to the invention reduces the mean particle size of the ice crystals. A typical mean particle size is between 20 and 50 ~m. A smaller mean particle size is desirable from two points of view. On the one hand, it improves heat transfer at the location of the cooling effect required so that a smaller volume of the cold transfer medium has to be conveyed per unit time. On the other hand, the rheological properties of the liquid ice are ccnsiderably better owing to the smaller mean particle size of the ice crystals. The pressure drop in the system is therefore lower, which saves pumping energy. In addition, the above-mentioned formation of an organic slime is suppressed.
The lower alcohol suitable for the cold transfer medium has to be soluble in water (or miscible with water) to at least such an extent that a single-phase system having an indicated proportion of the two substances is formed.
Preference is given to a lower alkanol miscible in all proportions with water, for example methanol, ethanol and isopropanol, or a mixture of such alkanols. The preferred alcohol is ethanol which can be used in the commercial denatured form. The water can be, but does not have to be, deionized. A preferable cold transfer medium contains from 5 to 30% by volume of the alcohol and from 70 to 95% by volume of water.
A suitable additive is selected from the above-mentioned classes of substances (1) to (6). Among the low molecular weight polycarboxylic acids (1), examples of preferred additives are dicarboxylic and tricarboxylic acids which contain a hydroxyl group and are therefore sufficiently soluble in the aqueous solution of the alcohol, for example malic acid and tartaric acid. The sorbic acid derivatives (2) which can be used include methyl sorbate, ethyl sorbate and sodium sorbate. Examples of preferred polyhydric alcohols (3) which may be mentioned are low molecular weight polyhydric alcohols such as ethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, glycerol and penta-erythritol. Aliphatic acids (4) or salts thereof which can be used include, for example, low molecular weight aliphatic monocarboxylic acids such as acetic acid and propionic acid, and low molecular weight hydroxy-monocarboxylic acids, lactic acid as well as their alkali metal salts. Anionic surfactants (5) which can be used as additive are, for example~ long-chain alkyl sulfates or s~fonates and also long-chain alkylaryl-sulfonates.
The additives can consist of one or more represent-atives from any one of the classes of substances mentioned or be combinations of a plurality of substances from a plurality of different classes of substances. These include combinations of two substances from two different classes of substances, namely (1) and (2), (1) and (3), (1) and (4), (1) and (5), (1) and (6), (2) and (3), (2) and (4), (2) and (5), (2) and (6), (3) and (4), (3) and (5), (3) and (6), (4) and (5), (4) and (6) or (5) and (6);
combinations of three substances from three different classes of substances, namely 0 (1), (2) and (3), (1), (2) and (4), (1), (2) and (5), (1), (2) and (6), (1), (3) and (4), (1), (3) and (5), (1), (3) and (6), (1), (4) and (5), (1), (4) and (6), (1), (5) and (6), (2), (3) and (4), (2), (3) and (5), (2), (3) and (6), (3), (4) and (5), (3), (4) and (6), (3), (5) and (6) or (4), (5) and (6);
combinations of four substances from four different classes of substances, namely (1), (2), (3) and (4), (1), (2), (3) and (5), (1), (2), (3) and (6), (1), (3), (4) and (5), (1)~ (3)~ (4) and (6)~ (1), (3), (5) and (6), (2), (3), (4) and (5), (2), (3), (4) and (6), (2), (3) , (5) and (6) or (3), (4), (5) and (6)i and also combinations of six substances from six different classes of substances (1) to (6).
The aqueous solution whose use is subject matter of the invention generally contains the additive in an amount of from 0.005 to 5% by weight, preferably from 0.1 to 0.5% by weight, based on the weight of the total aqueous solution including the additive. The optimum amount depends, inter alia, on the desired mean particle size, the lower alcohol used, its concentration in the aqueous solution and also on the desired cooling temperature and can be readily determined by guideline tests.
The aqueous solution may contain one or more further additives customary for a cold transfer medium, for example an additional flow improver or a foam inhibitor. The favour-able property profile of the cold transfer medium is notimpaired thereby.
It has also been found that the addition of a small amount of finely divided silica counteracts the sedimentation of the ice crystals which is not infrequently observed, particularly in the unagitated state. Silica suitable for this purpose is, for example, pyrogenic silicon dioxide having a mean particle size in the range from about 5 to about 20 nm.
A hydrophilic product of this type is preferred. Examples of pyrogenic silicon dioxide which can be used are, inter alia, commercially available under the trade-marks Aerosil~ and Cabot-Sil~. However, other non-pyrogenic finely divided silicas having a similar mean particle size are also an effective sedimentation inhibitor. Furthermore, the sediment-ation inhibition occurs in the case of all known aqueous solutions cf lower alcohols which are used as a liquid ice mixture, regardless of whether the liquid ice mixture contains the additives according to the invention and/or other additives. A preferred amount of the finely divided silica is from about 0.01 to 1% by weight based on the cold transfer medium.
The cold transfer medium according to the invention may be used in any customary refrigeration plants having separate circuit for a refrigerant and a cold transfer medium.
Temperatures below zero which can be achieved depend on the alcohol used and on the ratio of the alcohol to water. In the case of from 10 to 20% by weight of ethanol, about -15~C
can be achieved without the proportion of ice crystals which becomes ever greater with falling temperature substantially increasing the energy requirement for the circuit containing the cold transfer medium.
The following example illustrates the invention but should not be interpreted to restrict its scope as defined in the claims.
Example In a conventional refrigeration plant using ammonia as refrigerant, a mixture of 10% by volume of commercial ethanol denatured with methyl ethyl ketone, 90% by volume of water and 0.2% by weight of a mixture comprising one substance from each of the six classes of substances (1) to (6) (obtainable from IWC International, Marl, Federal Republic of Germany as Corrogard~ 36) is used as a cold transfer medium.
The pressure drop in the system is 0.45 bar, the specific throughput of the cold transfer medium needed for the required cooling performance is 92 l/min. After 3 months of uninterrupted operation, no corrosion and/or accumulation of organic slime was apparent on the heat exchange surfaces of V2A steel and in the copper pipes.
The addition of 0.1% by weight of finely divided silica (Cabot-Sil~ EH5) reliably suppresses the sedimentation tendency displayed by the liquid ice, particularly in the static state.
When an otherwise identical cold transfer medium without additive was used, the pressure drop was 0.51 bar and the specific throughput of the cold transfer medium was 103 l/min under otherwise identical conditions. ~he additional energy requirement for the circuit containing cold transfer medium is thus about 20%.
SOLUTIONS OF LOWER kLCOHOLS
The invention relates to a cold transfer medium consisting essentially of an aqueous solution of a lower alcohol containing a property-improving additive which may be a single substance or a combination of substances of two to six different classes of substances or containing finely divided silica as a sedimentation inhibitor.
Chlorofluorocarbons (CFCs) such as difluorodichloro-methane and trifluorochloromethane were previously widely usedas refrigerants, but have fallen into disrepute after it became known that they contribute to the destruction of the ozone layer around the earth and to the so-called greenhouse effect. The engineering measures which seek to reduce the amounts of CFCs, hydrochlorofluorocarbons (H-CFCs) or fluoro-carbons (FCs) required for a particular cooling performance include the separation of a refrigeration system into a refrigerant circuit and a circuit containing a cold transfer medium. In the first-mentioned circuit, the temperature of the refrigerant is still reduced by partial evaporation and indirect heat exchange takes place between the refrigerant and the cold transfer medium which circulates in the second circuit and provides its cooling effect at the desired location by taking up heat. For economic reasons, particularly in relatively large facilities such as air-conditioned buildings, supermarkets having a plurality of refrigerated or freezer chests or cool stores, this principle of separating O.Z. 5072 the refrigerant circuit and the circuit containing the cold transfer medium is also employed when one of the refrigerants mentioned are used.
Coolants based on ethylene or propylene glycol are at present widely used as a cold transfer medium. Although these coolants have a high specific heat and therefore a corresponding cooling performance, they display a temperature behaviour directly dependent on the cooling performance. For this reason, increasing use is being made more recently of a so-called liquid ice mixture comprising a water-soluble alcohol, generally ethanol, and water as a cold transfer medium which has a favourable heat transfer behaviour. This mixture is cooled in an ice generator specifically constructed for this purpose until part Gf the water freezes out in the form of fine ice crystals. A heat exchange surface is kept free mechanically so that growth of the ice crystals deposited there is prevented. The resulting two-phase system, also knGwn as liquid ice, is conveyed in a closed circuit and is readily pumpable. The mean particle diameter of the ice crystals in the liquid ice is about 100 ~m in the system based on ethanol/water which is customary nowadays. A particular problem in the liquid ice system is the deposition of an organic slime on the heat exchange surface and/or in pipes, which reduces heat exchange, increases the pressure drop in the system and makes frequent cleaning necessary.
It has now been found that the aqueous solution of a lower alcohol with an addition of (1) a low molecular weight polycarboxylic acid, (2) an ester or salt of sorbic acid, (3) a polyhydric alcohol, (4) an aliphatic acid or a salt of an aliphatic acid, (5) an anionic surfactant and/or (6) a sulfur-free triazole compound can be advantageously used as a cold transfer medium.
The additive employed according'to the invention reduces the mean particle size of the ice crystals. A typical mean particle size is between 20 and 50 ~m. A smaller mean particle size is desirable from two points of view. On the one hand, it improves heat transfer at the location of the cooling effect required so that a smaller volume of the cold transfer medium has to be conveyed per unit time. On the other hand, the rheological properties of the liquid ice are ccnsiderably better owing to the smaller mean particle size of the ice crystals. The pressure drop in the system is therefore lower, which saves pumping energy. In addition, the above-mentioned formation of an organic slime is suppressed.
The lower alcohol suitable for the cold transfer medium has to be soluble in water (or miscible with water) to at least such an extent that a single-phase system having an indicated proportion of the two substances is formed.
Preference is given to a lower alkanol miscible in all proportions with water, for example methanol, ethanol and isopropanol, or a mixture of such alkanols. The preferred alcohol is ethanol which can be used in the commercial denatured form. The water can be, but does not have to be, deionized. A preferable cold transfer medium contains from 5 to 30% by volume of the alcohol and from 70 to 95% by volume of water.
A suitable additive is selected from the above-mentioned classes of substances (1) to (6). Among the low molecular weight polycarboxylic acids (1), examples of preferred additives are dicarboxylic and tricarboxylic acids which contain a hydroxyl group and are therefore sufficiently soluble in the aqueous solution of the alcohol, for example malic acid and tartaric acid. The sorbic acid derivatives (2) which can be used include methyl sorbate, ethyl sorbate and sodium sorbate. Examples of preferred polyhydric alcohols (3) which may be mentioned are low molecular weight polyhydric alcohols such as ethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, glycerol and penta-erythritol. Aliphatic acids (4) or salts thereof which can be used include, for example, low molecular weight aliphatic monocarboxylic acids such as acetic acid and propionic acid, and low molecular weight hydroxy-monocarboxylic acids, lactic acid as well as their alkali metal salts. Anionic surfactants (5) which can be used as additive are, for example~ long-chain alkyl sulfates or s~fonates and also long-chain alkylaryl-sulfonates.
The additives can consist of one or more represent-atives from any one of the classes of substances mentioned or be combinations of a plurality of substances from a plurality of different classes of substances. These include combinations of two substances from two different classes of substances, namely (1) and (2), (1) and (3), (1) and (4), (1) and (5), (1) and (6), (2) and (3), (2) and (4), (2) and (5), (2) and (6), (3) and (4), (3) and (5), (3) and (6), (4) and (5), (4) and (6) or (5) and (6);
combinations of three substances from three different classes of substances, namely 0 (1), (2) and (3), (1), (2) and (4), (1), (2) and (5), (1), (2) and (6), (1), (3) and (4), (1), (3) and (5), (1), (3) and (6), (1), (4) and (5), (1), (4) and (6), (1), (5) and (6), (2), (3) and (4), (2), (3) and (5), (2), (3) and (6), (3), (4) and (5), (3), (4) and (6), (3), (5) and (6) or (4), (5) and (6);
combinations of four substances from four different classes of substances, namely (1), (2), (3) and (4), (1), (2), (3) and (5), (1), (2), (3) and (6), (1), (3), (4) and (5), (1)~ (3)~ (4) and (6)~ (1), (3), (5) and (6), (2), (3), (4) and (5), (2), (3), (4) and (6), (2), (3) , (5) and (6) or (3), (4), (5) and (6)i and also combinations of six substances from six different classes of substances (1) to (6).
The aqueous solution whose use is subject matter of the invention generally contains the additive in an amount of from 0.005 to 5% by weight, preferably from 0.1 to 0.5% by weight, based on the weight of the total aqueous solution including the additive. The optimum amount depends, inter alia, on the desired mean particle size, the lower alcohol used, its concentration in the aqueous solution and also on the desired cooling temperature and can be readily determined by guideline tests.
The aqueous solution may contain one or more further additives customary for a cold transfer medium, for example an additional flow improver or a foam inhibitor. The favour-able property profile of the cold transfer medium is notimpaired thereby.
It has also been found that the addition of a small amount of finely divided silica counteracts the sedimentation of the ice crystals which is not infrequently observed, particularly in the unagitated state. Silica suitable for this purpose is, for example, pyrogenic silicon dioxide having a mean particle size in the range from about 5 to about 20 nm.
A hydrophilic product of this type is preferred. Examples of pyrogenic silicon dioxide which can be used are, inter alia, commercially available under the trade-marks Aerosil~ and Cabot-Sil~. However, other non-pyrogenic finely divided silicas having a similar mean particle size are also an effective sedimentation inhibitor. Furthermore, the sediment-ation inhibition occurs in the case of all known aqueous solutions cf lower alcohols which are used as a liquid ice mixture, regardless of whether the liquid ice mixture contains the additives according to the invention and/or other additives. A preferred amount of the finely divided silica is from about 0.01 to 1% by weight based on the cold transfer medium.
The cold transfer medium according to the invention may be used in any customary refrigeration plants having separate circuit for a refrigerant and a cold transfer medium.
Temperatures below zero which can be achieved depend on the alcohol used and on the ratio of the alcohol to water. In the case of from 10 to 20% by weight of ethanol, about -15~C
can be achieved without the proportion of ice crystals which becomes ever greater with falling temperature substantially increasing the energy requirement for the circuit containing the cold transfer medium.
The following example illustrates the invention but should not be interpreted to restrict its scope as defined in the claims.
Example In a conventional refrigeration plant using ammonia as refrigerant, a mixture of 10% by volume of commercial ethanol denatured with methyl ethyl ketone, 90% by volume of water and 0.2% by weight of a mixture comprising one substance from each of the six classes of substances (1) to (6) (obtainable from IWC International, Marl, Federal Republic of Germany as Corrogard~ 36) is used as a cold transfer medium.
The pressure drop in the system is 0.45 bar, the specific throughput of the cold transfer medium needed for the required cooling performance is 92 l/min. After 3 months of uninterrupted operation, no corrosion and/or accumulation of organic slime was apparent on the heat exchange surfaces of V2A steel and in the copper pipes.
The addition of 0.1% by weight of finely divided silica (Cabot-Sil~ EH5) reliably suppresses the sedimentation tendency displayed by the liquid ice, particularly in the static state.
When an otherwise identical cold transfer medium without additive was used, the pressure drop was 0.51 bar and the specific throughput of the cold transfer medium was 103 l/min under otherwise identical conditions. ~he additional energy requirement for the circuit containing cold transfer medium is thus about 20%.
Claims (15)
1. A cold transfer medium for a refrigeration system consisting essentially of an aqueous solution of a water-soluble lower alcohol with at least one additive selected from the group consisting of:
(1) a low molecular weight polycarboxylic acid, (2) an ester or salt of sorbic acid, (3) a polyhydric alcohol, (4) an aliphatic acid or salt of an aliphatic acid, (5) an anionic surfactant, and (6) a sulfur-free triazole compound, or with finely divided silica.
(1) a low molecular weight polycarboxylic acid, (2) an ester or salt of sorbic acid, (3) a polyhydric alcohol, (4) an aliphatic acid or salt of an aliphatic acid, (5) an anionic surfactant, and (6) a sulfur-free triazole compound, or with finely divided silica.
2. The cold transfer medium as claimed in claim 1, wherein the additive used is the following combination of two substances from two different classes of substances:
(1) and (2), (1) and (3), (1) and (4), (1) and (5), (1) and (6), (2) and (3), (2) and (4), (2) and (5), (2) and (6), (3) and (4), (3) and (5), (3) and (6), (4) and (5), (4) and (6) or (5) and (6).
(1) and (2), (1) and (3), (1) and (4), (1) and (5), (1) and (6), (2) and (3), (2) and (4), (2) and (5), (2) and (6), (3) and (4), (3) and (5), (3) and (6), (4) and (5), (4) and (6) or (5) and (6).
3. The cold transfer medium as claimed in claim 1, wherein the additive used is the following combination of three substances from three different classes of substances:
(1), (2) and (3), (1), (2) and (4), (1), (2) and (5), (1), (2) and (6), (1), (3) and (4), (1), (3) and (5), (1), (3) and (6), (1), (4) and (5), (1), (4) and (6), (1), (5) and (6), (2), (3) and (4), (2), (3) and (5), (2), (3) and (6), (3), (4) and (5), (3), (4) and (6) or (3), (5) and (6).
(1), (2) and (3), (1), (2) and (4), (1), (2) and (5), (1), (2) and (6), (1), (3) and (4), (1), (3) and (5), (1), (3) and (6), (1), (4) and (5), (1), (4) and (6), (1), (5) and (6), (2), (3) and (4), (2), (3) and (5), (2), (3) and (6), (3), (4) and (5), (3), (4) and (6) or (3), (5) and (6).
4. The cold transfer medium as claimed in claim 1, wherein the additive used is the following combination of four substances from four different classes of substances:
(1), (2), (3) and (4), (1), (2), (3) and (5), (1), (2), (3) and (6), (1), (3), (4) and (5), (1), (3), (4) and (6), (1), (3), (5) and (6), (2), (3), (4) and (5), (2), (3), (4) and (6), (2), (3), (5) and (6) or (3), (4), (5) and (6).
(1), (2), (3) and (4), (1), (2), (3) and (5), (1), (2), (3) and (6), (1), (3), (4) and (5), (1), (3), (4) and (6), (1), (3), (5) and (6), (2), (3), (4) and (5), (2), (3), (4) and (6), (2), (3), (5) and (6) or (3), (4), (5) and (6).
5. The cold transfer medium as claimed in claim 1, wherein the additive used is the following combination of five substances from five different classes of substances, namely:
(1), (2), (3), (4) and (5), (1), (2), (3), (4) and (6), (1), (2), (3), (5) and (6), (1), (2), (4), (5) and (6), (1), (3), (4), (5) and (6) or (2), (3), (4), (5) and (6).
(1), (2), (3), (4) and (5), (1), (2), (3), (4) and (6), (1), (2), (3), (5) and (6), (1), (2), (4), (5) and (6), (1), (3), (4), (5) and (6) or (2), (3), (4), (5) and (6).
6. The cold transfer medium as claimed in claim 1, wherein the additive used is a combination of six substances from six different classes of substances (1) to (6).
7. The cold transfer medium as claimed in claim 1, wherein the aqueous solution contains finely divided silica as a sedimentation inhibitor.
8. The cold transfer medium as claimed in any one of claims 1 to 6, wherein finely divided silica is also added.
9. The cold transfer medium as claimed in any one of claims 1 to 6, wherein the additive of class (1) is selected from dicarboxylic and tricarboxylic acids containing a hydroxyl group, the additive of class (2) is selected from methyl sorbate, ethyl sorbate and sodium sorbate, the additive of class (3) is selected from glycol, dipropylene glycol, triethylene glycol, glycerol and pentaerythritol, the additive of class (4) is selected from acetic acid, propionic acid and lactic acid as well as their alkali metal salts, the additive of class (5) is selected from long-chain alkyl sulfates or sulfonates and long-chain alkylarylsulfonates.
10. A cold transfer medium for a refrigeration system having separate circuits for a refrigerant and a cold transfer medium, the cold transfer medium being an aqueous solution of a water-soluble lower alkanol and containing at least one additive selected from the group consisting of:
(1) a low molecular weight polycarboxylic acid, (2) an ester or salt of sorbic acid, (3) a polyhydric alcohol, (4) a low molecular weight aliphatic monocarboxylic acid or hydroxy-monocarboxylic acid or a salt thereof, (5) an anionic surfactant, and (6) a sulfur-free triazole compound, wherein the additive is chosen and employed within an amount of 0.005 to 5% by weight based on the aqueous solution such that the cold transfer medium, when cooled in an ice generator, forms a readily pumpable liquid ice containing fine ice crystals having a mean crystal size smaller than that when the additive is not employed.
(1) a low molecular weight polycarboxylic acid, (2) an ester or salt of sorbic acid, (3) a polyhydric alcohol, (4) a low molecular weight aliphatic monocarboxylic acid or hydroxy-monocarboxylic acid or a salt thereof, (5) an anionic surfactant, and (6) a sulfur-free triazole compound, wherein the additive is chosen and employed within an amount of 0.005 to 5% by weight based on the aqueous solution such that the cold transfer medium, when cooled in an ice generator, forms a readily pumpable liquid ice containing fine ice crystals having a mean crystal size smaller than that when the additive is not employed.
11. The cold transfer medium as claimed in claim 10, wherein the aqueous solution contains 5 to 30% by volume of ethanol and 70 to 95% by volume of water.
12. The cold transfer medium as claimed in claim 10 or 11, wherein the additive (1) is malic acid or tartaric acid;
the additive (2) is methyl sorbate, ethyl sorbate or sodium sorbate; the additive (3) is ethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, glycerol or penta-erythritol;
and the additive (4) is acetic acid, propionic acid, lactic acid or an alkali metal salt of these acids.
the additive (2) is methyl sorbate, ethyl sorbate or sodium sorbate; the additive (3) is ethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, glycerol or penta-erythritol;
and the additive (4) is acetic acid, propionic acid, lactic acid or an alkali metal salt of these acids.
13. A cold transfer medium for a refrigeration system having separate circuits for a refrigerant and a cold transfer medium, the cold transfer medium being an aqueous solution of a water-soluble lower alkanol and containing finely divided silica having a particle size in the range of from about 5 to about 20 nm in an amount effective to inhibit sedimentation of ice crystals when the cold transfer medium is cooled in an ice generator to form a readily pumpable liquid ice containing the ice crystals.
14. The cold transfer medium as claimed in claim 13, wherein the aqueous solution contains 5 to 30% by volume of ethanol and 70 to 95% by volume of water.
15. A refrigeration system having separate circuits for a refrigerant and a cold transfer medium, wherein the cold transfer medium is as defined in any one of claims 1 to 14.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19629578A DE19629578A1 (en) | 1996-07-23 | 1996-07-23 | Use of aqueous solutions of lower alcohols as refrigerants |
| DE19629578.5 | 1996-07-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2210902A1 true CA2210902A1 (en) | 1998-01-23 |
Family
ID=7800524
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002210902A Abandoned CA2210902A1 (en) | 1996-07-23 | 1997-07-21 | Use as cold transfer media of aqueous solutions of lower alcohols |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0821045A1 (en) |
| JP (1) | JPH1067983A (en) |
| CA (1) | CA2210902A1 (en) |
| DE (1) | DE19629578A1 (en) |
| NO (1) | NO973389L (en) |
| ZA (1) | ZA976463B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019210394A (en) * | 2018-06-06 | 2019-12-12 | 富士通株式会社 | Heat storage material, heat transfer device and energy harvester |
| JP7437028B2 (en) * | 2020-05-13 | 2024-02-22 | 感動創出工場ジーンファクトリー株式会社 | Cooling media, freezers and frozen product manufacturing methods |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1810946A (en) * | 1929-09-07 | 1931-06-23 | Du Pont | Noncorrosive solutions |
| US4210549A (en) * | 1979-01-02 | 1980-07-01 | Basf Wyandotte Corporation | Hydroxybenzoic acid as pH buffer and corrosion inhibitor for alkali metal silicate-containing antifreeze compositions |
| JPS57190073A (en) * | 1981-05-20 | 1982-11-22 | Mitsui Toatsu Chem Inc | Brine composition of low viscosity |
| GB8606901D0 (en) * | 1986-03-20 | 1986-04-23 | Shell Int Research | Corrosion-inhibiting heat-transfer composition |
| CA2002224A1 (en) * | 1989-02-16 | 1990-08-16 | Alan B. Gancy | Anti-icing/deicing compositions, and method for their manufacture |
| US5266228A (en) * | 1991-08-29 | 1993-11-30 | Basf Corporation | Corrosion-inhibiting automotive coolant solutions containing effective amounts of sodium silicate having a low ratio of silica to sodium oxide |
| ES2103888T3 (en) * | 1992-04-06 | 1997-10-01 | Texaco Services Europ Ltd | CORROSION INHIBITING ANTIFREEZE FORMULATIONS. |
| US5320772A (en) * | 1992-05-18 | 1994-06-14 | Empire Products Packaging Development, Inc. | Composition for cleaning fruits and vegetables |
| FR2721941B1 (en) * | 1994-06-29 | 1996-10-04 | Bp Chemicals Snc | ANTIFREEZE COMPOSITION AND AQUEOUS FLUID COMPRISING THE COMPOSITION |
| FR2726281B1 (en) * | 1994-10-28 | 1997-10-03 | Profroid Ind Sa | LIQUID-CARRYING LIQUID AND COMPOSITION FOR THE PREPARATION OF SUCH A LIQUID |
-
1996
- 1996-07-23 DE DE19629578A patent/DE19629578A1/en not_active Withdrawn
-
1997
- 1997-05-28 EP EP97108553A patent/EP0821045A1/en not_active Withdrawn
- 1997-07-21 CA CA002210902A patent/CA2210902A1/en not_active Abandoned
- 1997-07-22 ZA ZA9706463A patent/ZA976463B/en unknown
- 1997-07-22 JP JP9195385A patent/JPH1067983A/en active Pending
- 1997-07-22 NO NO973389A patent/NO973389L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| NO973389D0 (en) | 1997-07-22 |
| JPH1067983A (en) | 1998-03-10 |
| NO973389L (en) | 1998-01-26 |
| DE19629578A1 (en) | 1998-01-29 |
| EP0821045A1 (en) | 1998-01-28 |
| ZA976463B (en) | 1998-02-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |