CS209581B1 - Heat transfer medium - Google Patents

Abstract

Heat transfer medium for useful heat transfer between certain environments using a liquid medium. The invention solves the technical problem of using a non-toxic fluid, which has not been used before, as a heat or cold carrier. Essence of the invention: Heat transfer medium containing 1 to 79 parts by weight of an ethanolamine-based substance selected from the group consisting of monoethanolamine, diethanolamine or triethanolamine either alone or in a mixture, further 1 to 40 parts by weight of an aminocarboxylic acid selected from the group consisting of iminodioic acid, nitrilotriotic acid, ethylenediaminetetraacetic acid, 1,2-diamine-cyclohexane-N,N, N',N'-tetraacetic acid and, bis-2-aminoethyl ether-N,N,N',N'-tetrapotassium, their salts and derivatives, alone or in a mixture, and 20 to 90 parts by weight of water. The invention can be used in all cases where heat or cold carriers are used.

Description

The invention relates to a heat transfer medium, if necessary diluted with water.

According to the general requirements of world technology, heat transfer fluids must have certain physical properties in order to fulfill their function. In particular, they must be perfectly soluble in water, have low viscosity, good thermal conductivity, high specific heat, increased boiling point, reduced melting point and perfect surface wettability. In the event that the heat transfer fluid solidifies due to low temperature, it must form only individual fine crystals; when diluted with hard water, it must have softening effects and must have the ability to dissolve boiler scale deposits and metal oxidation products. Above all, however, the heat transfer fluid must not be toxic and the raw materials for preparation must be easily accessible.

With regard to the aforementioned requirements, numerous substances were tested, which, due to their physical properties, but especially their viscosity and density, seemed suitable for fulfilling the tasks set.

Heat transfer substances, which are known in the current world technology and which are used for useful heat transfer, often have a strong corrosive effect and therefore an admixture of inhibitors must be added to them, which are, however, harmful due to their toxicity. For example, heat transfer substances based on polyol alcohols, their polymers and. derivatives, such as glycol and its derivatives, are known; the disadvantage of their physical properties is, however, considerable viscosity, low specific heat, low to very low thermal conductivity impairing heat transfer. Their other shortcomings are toxicity and lack of starting raw materials.

In comparison with the above-mentioned substances, substances belonging to the extensive group of aminocarboxylic acids, in which several carboxyalkyl groups are bound to the nitrogen atom, have proven to be more advantageous heat transfer media. At present, some of them are used for the treatment of fabrics intended for rubberization, in particular for the removal of so-called rubber poisons such as residues of iron, copper and manganese, for the treatment of water during bleaching with hydrogen peroxide, for dyeing with those dyes that are free from metals that these aminocarboxylic acids bind. They are also used in optical brightening and other finishing processes such as washing and bleaching, and in particular in the treatment of white or light-colored goods that are in danger of yellowing or being stained by stains caused by iron compounds (Cheraa zpravod (1971) l). Other of the mentioned substances find their application in the leather and paper industries, and in the chemistry sector as a component of stabilizing baths in color photography; their use is also known as an auxiliary agent for alkaline cleaning of boilers and for breaking down scale and boiler scale, for softening feedwaters * · _ á' for low-pressure and medium-pressure boilers, etc. (Chema zpravod (1970) 1). They are also an important reagent in analytical chemistry (Přibil R.: Complexes in Chemical Analysis NCSA V, Prague (1957) 43), but their use as heat transfer media has not been known or proposed until now.

Further tests revealed that these substances, which by themselves have a relatively suitable viscosity (at 0 °C 3.7 ΙΟ^.ηΑββο“ ¹ , at 50 °C 2.3 10 ⁶ .m ² .sec“ ¹ ) and density (at 23 °C 1.058 to 1.47 g/os?), can achieve even more favorable physical parameters in suitable mixtures (for example, viscosities at 0 °C 2.2 to 2.9 and at 50 °C 1.5 to 1.6 10“ ⁶ .m.seo).

The disadvantages of previously known means are eliminated by the heat-transferring, water-dilutable medium according to the invention, the essence of which is that it contains 1 to 79 parts by weight of a substance based on ethanolamine, selected from the group including monoethanolamine HgN - CHg.CHgGH, diethanolamine

HN - (CHg.CHgOH^ or triethanolamine N - (eHg.CHgCH)^ either alone or in a mixture, 1 to 40 parts by weight of an aminocarboxylic acid selected from the group consisting of iminodioic acid, nitrilotriotic acid, ethylenediaminetetraacetic acid, 1,2-diaminocyclohexane-N,N,N',N*-tetraacetic acid and bis-2-aminoethyl ether-N,H,N',N'-tetraacetic acid, its salts and derivatives, alone or in a mixture, 20 to 90 parts by weight of water.

Salts of aromatic carboxylic acids include, for example, salts with alkali metals, with alkaline earth metals, salts based on amines, etc.

Compared to previously known heat transfer media, such as glycol-based media, for example 1,2-propylene glycol, the advantage of the heat transfer media according to the invention is lower average viscosity values, especially in the temperature range of 0 to 40 °C.

The advantages of this solution are apparent from the following examples of embodiments, which illustrate the essence of the invention without limiting it in any way.

Example 1.

The heat exchange medium is a mixture of 75% by weight of triethanolamine (N-CCH 3 .CH 3 GH ) 2 and 22.5% by weight of disodium salt of ethylenediaminetetraacetic acid, which is diluted with water to a 20% by weight solution.

Example 2.

The heat exchange medium is a mixture of 41.67% by weight of diethanolamine HÇ-(CH ₂ .CH ₂ 0H) ₂ , 41.66% by weight of triethanolamine N-(OH ₂ .OH ₂ OH)^» 8.34% by weight of ethylenediaminetetraacetic acid and 8.33% by weight of ethylenediaminetetraacetic tetrasodium salt. This mixture is diluted with water to a 30% by weight solution when used.

> Table

Physical properties of the heat transfer media given in examples 1 and 2

1. Viscosity (10“ ⁶ .m ^{1 2} .sec~J·)

Example δ. Temperature in °C

0 10 20 30 40 50 1 2.9 2.3 1.8 1.7 1.6 1.5 2 2.2 2.1 2.0 1.6 1.5 1.6 control 8.3 5.1 3.6 2.3 1.9 1.4

2, Density (g/csP) check

1.06042

1.06610 not detected

3. Specific expansion in volume % (cooled from 24 to 0 °C)

Example è. ,

0.7 .2 1.8

4. Freezing point in ®G

- 9

- 10 check - 15

5. Expansion during solidification in % volume.

3.0

3.2 J

6. Heat capacity of liquids in kg.°K (pp&specific value in the range from 0 to 40 °C), 3759.9

3722.24

Note:

⁺ ) control sample of the previously used heat transfer material based on 1,2-propylene glycol

Claims (1)

The heat-conducting, water-dilutable medium comprises 1 to 79 parts by weight of ethanolamine base, selected from the group consisting of monoethanolamine, dlethanolamine or trlethanolamine either alone or in admixture, furthermore from 1 to 40 parts by weight. selected from the group consisting of 1-aminodioic acid, nitrillotriootic acid, ethylenediaminetetraootic acid, 1,2-diamino-cyclohexane-N, N, N ', N'-tetraootovone and bis-2-aminoethyl ether-N, N, N', N'- % tetraacetate, its salts and derivatives, alone or in admixture, and 20 to 90 parts by weight of tetraacetic acid; water.