TWI278508B - Heat transfer medium and its preparation method and use - Google Patents

Abstract

The present invention relates to one kind of heat transfer medium including one or several kinds of salt aqueous solution, in which at least one kind of the salt is coordination compound formed with one or several kinds of metal ion of Cu, Ag, Au, Ni, Cr, Zn, Ti and Co, and organic acid or inorganic acid. Optionally, the coordination compound includes ammonia, and the heat transfer medium has pH value of 6-10. The present invention also relates to the preparation of the heat transfer medium and its application in heat transfer apparatus.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to a heat transfer medium, and more particularly to a heat transfer medium comprising a composite inorganic salt aqueous solution; the present invention also relates to a process for the preparation of the medium and to the use of the medium. [Prior Art]

In the field of heating, the heat transfer medium used is generally water and/or water vapor. In a few industries, oil or some gas is also used as a heat transfer medium. The gas medium has a small thermal conductivity and a low thermal conductivity. However, although the thermal conductivity of oil-based media is slightly larger, the use of oil for heating is complicated and the cost is greatly increased. The most widely used is the water medium, which has the disadvantage of having a small thermal conductivity and not completely absorbing heat. In addition, the aqueous medium often contains impurities, which tend to scale and corrode metal pipes, especially after scale formation, which seriously affects heat transfer. Therefore, many people have done a lot of work on descaling and anti-corrosion, and have published many patents. For example, CN 1038693, 1066432, 1160684, 1293153, 1349940, and 1442375, and JP 59-173192 and the like. Among them, phosphoric acid or bismuth and humic acid, and amine or salt salts are mainly added to the aqueous medium to eliminate scale or to prevent corrosion. However, none of these patents deals with the work of heat transfer media, and does not suggest the use of complex inorganic salts, especially salt solutions containing complex compounds, to increase the thermal conductivity of aqueous media. In addition, the thermal efficiency of convective heat transfer formed by using water or oil flowing in the pipe is relatively low, and the use of strong latent heat of vaporization in the phase change process can greatly improve the heat exchange efficiency during evaporation, and can be greatly improved when condensing Heat exchange efficiency, accompanied by convective heat transfer.

O:\91\91190-930218.DOC 1278508 Patent Application No. 931〇3352 fx > 3 / Chinese Manual Replacement Page (February 1995) / The inventor filed two patents in 1990, The heat transfer medium disclosed in the patent cn 1048752 is a mixture of potassium citrate, potassium sulphate, distilled water and alcohol in a ratio of 丨: 〇〇 5 : 8 : the disadvantage is the heat transfer of the medium The effect is not ideal, and the compatibility with the metal pipe is poor, and it is easy to generate non-condensing gas, which affects the service life. Therefore, it is urgent to have a large latent heat of vaporization, a large thermal conductivity, a good heat transfer effect, and no corrosion (4) Lang can be an environmentally friendly heat transfer medium. SUMMARY OF THE INVENTION Therefore, the object of the present invention is to find a medium which is suitable for heat transfer and heat exchange in a closed system by using a phase change, thereby improving the heat conduction and heat transfer rate, thereby achieving the purpose of high efficiency, energy saving and environmental protection. SUMMARY OF THE INVENTION One object of the present invention is to provide an excellent heat exchanger which has a large heat of vaporization, a good heat conduction effect, and no corrosiveness. The heat transfer medium of the present invention comprises an aqueous solution of one or more salts, wherein at least one of the salts is formed of one or more metal ions selected from the group consisting of copper, silver, gold, nickel, chromium, and the organic acid or inorganic acid. In the case of a complex, the complex optionally comprises ammonia, the heat transfer medium having a pH of 6-1 Torr, preferably 7. The heat transfer medium of the present invention further comprises a salt of an inorganic and/or organic acid with a metal or alkaline earth metal to further improve the properties of the medium and to eliminate odor. ', the monthly heat transfer 'I shell inorganic acid includes hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid or a mixture thereof, of which hydrochloric acid and / or phosphoric acid are preferred, and the organic acid includes humic or contains C]-Cr or more An acid which is substituted or unsubstituted, preferably having one or more phono and/or ke group substituted organic acids, such as formic acid, B

Ο.Λ91 \9 JJ 90-950203. DOC * 6 - 1278508 Patent Application No. 093103352 _ % ) Chinese Manual Replacement Page (February 95) Acid: Propionic acid, oxalic acid, citric acid, succinic acid, C Triacid, base-substituted Ding & C, hydroxyglutaric acid or a mixture thereof, of which humic acid is preferred. Another object of the present invention is to provide a heat transfer medium comprising dissolving one or more salts in water to form at least one type of metal ions of gold, mud, chromium, zinc, titanium (tetra) and organic acids and/or inorganic acids. The complex may optionally comprise ammonia and then the heat transfer medium is formulated to ΡΗ=6-1〇' preferably to 7. In the case of a plurality of salts, the inorganic or organic acid salt is first dissolved, and optionally the humate or humate is dissolved to form a fault, and the pH is adjusted to pH = 6] G, preferably to 7. Generally, it is formulated by using sodium hydroxide or emulsified potassium or hydrogen hydroxide. If acid is required, hydrochloric acid and/or scaly acid are generally used. Maoyue has a purpose to provide the heat transfer medium, which can be used for heat transfer in a heat transfer device using liquid heat transfer, for example, in the field of heating, greenhouses, vehicles Heating, industrial drying, various heat exchangers, heat exchangers, showers, hot air curtains, solar energy, and waste heat utilization. It is still another object of the present invention to provide a heat transfer device in which the heat transfer medium of the present invention is used. This & month person lx now 'some complex chemical media containing complex compounds have large latent heat and high thermal conductivity. For this reason, the inventors have conducted a large number of tests to select a plurality of inorganic and organic acid salts. In addition to the above two purposes, the heat transfer medium f has good stability under working temperature and labor, fast heat conduction, and is not afraid of outdoor in the cold north. (1) There is no doubt that the heat transfer medium of the present invention replaces water for heating. The advantages in the system are huge, and the benefits are very good.

O:\91\91I90-950203.DOC -7- 1278508 The advantages of the eve are clearly visible, some of which will be pointed out below. To add salt to the water, it must be completely dissolved in order to vaporize, because the solid solitary can not talk about the latent heat of vaporization in the heating official road. Therefore, the f τ condition of the heat transfer medium of the present invention must be dissolved, in other words it is a salt solution. The inventors have found that the addition of a metal salt to water greatly improves the heat transfer efficiency, and the addition of salt brings about two problems, that is, some salts have low solubility, and some salts have insect a. The Applicant has surprisingly found through a number of trials that the addition of the complex compound solves both of these problems. For the thermal conductivity of Tima, it is preferred to add one or more metal salts, such as copper, gold nickel, 'zinc, titanium, cobalt or a mixture thereof. Among these gold='s salts, there are some salts whose solubility is small, so they are made into a complex compound so that the solution can be solved. ^ To ensure the stability of the heat transfer medium under the conditions of the Guardian', and in order to maintain the chemical nature of the heat transfer medium, some potting salts such as mineral or organic acid salts of metal or soil metal may be added. There is no strict limit to this salt, as long as it is completely dissolved. The inorganic acid includes hydrochloric acid, sulfuric acid, nitric acid, linonic acid or a mixture thereof; among them, hydrochloric acid and/or phosphoric acid are preferred; since scaly acid also protects the pipeline from corrosion. The metal or soil test metal is preferably potassium, sodium, dance, magnesium, sulphur, or a mixture thereof, and the like, and the ion is particularly preferable because the money ion easily forms a complex with a metal such as copper or a complex. The organic acid includes humic acid or a mono- or poly-, substituted or unsubstituted acid containing hydrazine, preferably an organic acid having a hydrazine or a hydroxy group and/or a carboxy group, such as formic acid, acetic acid, and C. Acid, oxalic acid, citric acid, succinic acid, triglyceride, trans-substituted succinic acid, glutaric acid or a mixture thereof. when

O: \91\91190-930218.DOC 1278508 An aromatic acid such as hydroxybenzoic acid can also be used, however, aromatic acid is not preferred from the viewpoint of the toxicity of the aromatic acid and the solubility of the metal salt thereof. In addition, the biggest disadvantage of using organic acids is that they are easy to bring off odors, so they are generally not used. However, we have unexpectedly found that an organic acid is particularly suitable, which is a humic acid, and therefore it is preferred to add humic acid to the present invention. It is not limited to any professional theory. We believe that humic acid is a macromolecular structure with weak acidity. Its chemical and complexing ability (adsorption) is determined by multiple carboxyl groups, hydroxyl groups and other active groups in the molecular structure. The group decided. Humic acid molecules (hereinafter referred to as HA) form a porous agglomerate similar to grape bunches by association in an acidic medium or under the action of a two or more neutral salt to have a large specific surface area. It has high electrostatic attraction and strong ion exchange capacity, and can complex heavy metal, alkali metal or alkaline earth metal to form a ligand. Its complexing ability (adsorption) conforms to the Langmuir equation, for example, the horizontal pair is "adsorption isotherm equation. G = C / (0.01C + 0.09) where G is the equivalent of Cd2+ per gram of HA, the balance of CgCd2+ Concentration, in mg/L. Of course, the heat transfer medium of the present invention can form some complexes such as K2[Co(S〇4)2] or K2S04 · Al2(S〇4)3. 24H20, etc. The amount of salt added is not strictly limited, but it is not more than 4〇~% (% by weight), which is mainly determined according to user requirements. When the amount is too small, for example, less than 0.5 wt%, it is not easy to achieve heat transfer efficiency. When the amount is more than 40% by weight, the purpose of completely eliminating corrosiveness is not easily achieved, and when the amount is too large, the latent heat of vaporization is rather lowered. The total amount of the salt is generally preferably 丨_25%, more preferably 2-15% by weight 〇

O:\91\9I190-9302I8.DOC 1278508 - Patent application No. G93, No. 103352 was revised on the 3rd of the month to be replaced by the page 又中又月曰曰才! Page (February 95) Selection of the variety and quantity of salt Mainly according to the user's use requirements, such as the temperature of the starting temperature, the speed of heat transfer, the size of latent heat of vaporization, the corrosion resistance of a device, etc., the type and amount of salt added can be changed to meet the requirement of using x. The heat transfer medium of the present invention is easy to prepare, and, in other words, it is commercially available that various chemicals are dissolved. The temperature at the time of dissolution is not strictly limited, and heating can accelerate the dissolution 'generally preferably 20 to 8 (rc. The dissolution order is also not strictly dry: T ' - directly dissolves the chemical to form a complex; or preferably dissolves when using a plurality of salts Inorganic or organic acid salts, redissolving other chemicals capable of forming a complex. Finally, the inorganic or organic acid or ammonia or water is used to formulate the product' such that the pH of the final product is neutral. In a preferred embodiment, the first dissolution Copper nitrate, then adding ammonia to form a complex, and then arranging ΡΗ=6·1()β with hydroxide steel. In another preferred embodiment, adding gasified copper and humic acid to solution is adjusted to ρΗ=6 · 1 () It is not difficult to see that the product of the present invention is by no means limited to a liquid solution, can be completely turned into a solid product, or a two-package solid product, which can be conveniently formulated into a solution when used. And / or a larger amount of salt, or when prepared in a low temperature environment, the resulting product may have a precipitation, then a further filtration step is required. In the field of heating, especially in the field of replacing water medium heating, since the latent heat of vaporization of the heat transfer medium of the invention is larger than water, the heat conduction efficiency is good, and the heat transfer speed is fast, energy can be greatly saved. In addition, the heat transfer medium of the present invention does not have any Corrosion, existing pipeline equipment can be utilized. [Embodiment] O: \91\91190-950203.DOC -10- 1278508 The present invention will be described in detail below with reference to the embodiments. [Specific embodiment details] Example 1 Weigh llg potassium sulfate, 5g potassium chloride and 3g copper nitrate in 5〇〇g water, heat to 60 C ' and add 1 g humic acid, hydrogen The sodium oxide was formulated to pH = 7, and water was added to the total amount of lkg to obtain a completely dissolved aqueous product, and the product properties were examined. Example 2 14 g of copper sulfate and 110 g of sodium nitrate were dissolved in 500 g of water, 6 g of aqueous ammonia was added, and 70 g of magnesium chloride was added. Add lg humic acid, mix with ammonium hydroxide and potassium hydroxide (1:1) to pH = 8, and add water to the total amount of lkg to obtain a completely dissolved aqueous product, to detect product rot and heat transfer efficiency. Example 3 Take 100g Copper nitrate, 200g sodium dihydrogen phosphate and 78g potassium chloride were placed in 5〇〇g water, 2g of triglyceride was added, heated to 60 ° C to completely dissolve, adjusted to pH=9 with sodium hydroxide, and water was added. The total amount is ikg. After filtration, a completely dissolved aqueous product is obtained. Example 4 25 g of vaporized copper and lg humic acid are taken, heated to 60 ° C, completely dissolved, and then adjusted to pH = 6 with ammonium sulfate, such as water to total The amount of lkg is obtained. A completely dissolved aqueous product is obtained. Example 5 7 g of copper sulfate and 8 g of potassium hydride and 4.5 g of zinc nitrate are dissolved in 500 g of water, and O:\91\91I90-930218.DOC -11 - 1278508 heat to 40 °C, then add 55g humic acid, mix with sodium hydroxide to pH=7, add water to a total of 1 kg. A fully dissolved aqueous product is obtained to test product performance. Example 6 7 g of copper nitrate, 6 g of potassium chloride and 6.9 g of zinc phosphate were dissolved in 500 g of water, heated to 60 ° C, then 〇. lg humic acid was added, and the pH was adjusted to 7 with sodium hydroxide, and water was added thereto. The total amount is lkg. A fully dissolved aqueous product is obtained to test product performance. Example 7 Dissolve 99 g of sulfuric acid and 60 g of chlorinated clock and 40 g of copper acid in 500 g of water, heat to 60 ° C, add lg humic acid, mix with sodium hydroxide to pH = 7, add water to the total amount For 1 kg. A completely dissolved aqueous product was obtained and the product properties were examined. Example 8 1 50 g of potassium sulfate and 120 g of potassium chloride and 80 g of copper nitrate were dissolved in 500 g of water, heated to 60 ° C, and then 15 g of humic acid and 30 g of sodium valerate were added, and the pH was adjusted to pH with sodium hydroxide. =7, add water to the total amount of lkg. After cooling to room temperature, a completely dissolved aqueous product was obtained after filtration, and the product properties were examined. Example 9 5 g of copper sulfate and 8 g of sodium phthalate were dissolved in 500 g of water, 2 g of aqueous ammonia was added, 7 g of gasification town was added, 2 g of humic acid was added, and sodium hydroxide was used to adjust to pH=7, and water was added to the total amount of lkg. . After cooling to room temperature, a completely dissolved aqueous product was obtained, and the product properties were examined. Example 10 O:\9I\91190-930218.DOC -12- 1278508 Take 20 g of copper sulfate and 100 g of sodium nitrate dissolved in 500 g of water, add 150 g of chlorinated town, add 100 g of rot The acid is adjusted to pH=7 with hydrazine hydroxide and water is added to the total amount of lkg. After cooling to room temperature, a small amount of precipitate was obtained, and after filtration, a completely dissolved aqueous product was obtained, and the product properties were examined. Example 11 50 g of copper nitrate, 110 g of sodium dihydrogen phosphate and 39 g of zinc chloride were dissolved in 500 g of water, heated to 60 ° C to completely dissolve, and 1 g of humic acid was added, and the pH was adjusted to 7 with sodium hydroxide. , add water to the total amount of lkg. After filtration, a completely dissolved aqueous product was obtained, and the product properties were examined. Example 12 5 g of copper citrate, llg of dihydrogen hydride and 5 g of potassium chloride were dissolved in 500 g of water, heated to 60 ° C to completely dissolve, and 1 g of sodium succinate was added, followed by 12 g of humus. The acid was mixed with sodium hydroxide to pH = 7, and water was added until the total amount was lkg. Cool to room temperature, and if precipitated, filter to obtain a completely dissolved aqueous product to determine product properties. Example 13 100 g of zinc sulfide and 90 g of magnesium nitrate were dissolved in 500 g of water, and then 10 g of trisodium phosphate was added thereto, heated to 60 ° C, completely dissolved, and then adjusted to pH = 7 with sodium hydroxide, and water was added to a total amount of 1 Kg. A fully dissolved aqueous product is obtained to test product performance. Example 14 180 g of zinc silicate was dissolved in 500 g of water, and then 20 g of trihydrate was added thereto, heated to 60 ° C, dissolved, and then adjusted to pH = 7 with sodium hydroxide, and water was added thereto to a total amount of 1 kg. After filtration, a completely dissolved aqueous product was obtained, and the product properties were examined. O:\91\9U90-930218.DOC -13 - 1278508 Example 15 Take 70g of copper sulfate and 8〇g of gasification and 4〇g of zinc nitrate dissolved in 5〇〇g water and heat to 6〇°C' Add 1 〇8 rot of solubilic acid, mix with sodium hydroxide to PH=7, and force water into the total amount of lkg. Cool to room temperature, transition if there is a sink, and then obtain a completely dissolved aqueous product to test product properties. Example 16 UOg copper sulfate and 16 〇g of potassium hydride and 99 g of zinc nitrate were dissolved in 5 〇〇g of water, heated to 6 (TC, plus lg rot of lean acid, and adjusted to pH=7 with sodium hydroxide) Water was added to a total amount of lkg. After complete hydrazine, a completely dissolved aqueous product was obtained, and the product properties were examined. Example 17 70 g of copper nitrate, 60 g of potassium amide and 6 g of zinc phosphate were dissolved in 5 〇〇 water and heated to 4 (TC, add l〇g humic acid, mix with sodium hydroxide to pH=7, add water to the total amount of lkg. Cool to room temperature, if there is precipitation, transition, then get a completely dissolved aqueous product, The product properties were tested.Example 18 100 g of copper nitrate, 120 g of potassium chloride and 120 § phosphorus were dissolved in 5 〇〇g of water 'heated to 4 (TC, then 10 g of sodium benzoate was added, and sodium hydroxide was added to PH= 7. Add water to the total amount of 丨]^. Cool to room temperature, if there is precipitation, filter to obtain a completely dissolved aqueous product, and test the product performance. Test test on the product of the invention separately heat transfer efficiency, service life, rot # Sex test, and measure the amount of media loss and X flaw detection. All test tests are According to the conventional method in the field, in the detection of heat transfer O: \ 9t \ 91190-930218. DOC - 14 - 1278508 efficiency 蛉 ' with the aqueous medium as a control test. For example, separately measured this month; I shell and water medium The inlet and outlet temperatures of the circulatory system, the cooling water flow rate and the equilibration time, and then input the heat according to the input power, calculate the heat absorbed by the cooling water, and obtain the thermal efficiency of the system. The main service life of the medium, such as aging test, medium loss Test and corrosive test. - The equipment for aging test is very simple. Generally, 4mm hot-rolled steel plate is used as the furnace body, and the outer series of heat-dissipating fins of the seamless steel pipe is made into a heater. Heating in an electric furnace. After heating for a certain period of time, the temperature of the furnace body and the temperature of the medium at both ends are measured, and then the heating is continued for 432 〇〇 small: the end temperature of the person is observed 'there is no excessive cooling or temperature drop at the end, and the certificate is a " At the same time, the weight of the medium before and after heating is weighed, and the residual medium in the furnace body and the pipeline is completely evaporated. After the liquid is weighed into a weighing bottle and weighed, the sum of the residual medium and the amount of medium after the addition of # 432 is compared with the amount of medium before heating. The life test is the size of the conventional heating system. The nut, steel plate, seamed steel pipe and seamless steel pipe are kept for 43200 hours in the test immersion 9()_ order medium enamel, and then the weight loss of each sample is weighed, so that the thickness of the rot can be changed. The commercially available riding line flaw detector detects the furnace body and the inner wall of the heat exchanger and observes the condition of the metal crystal crucible. The heat transfer efficiency test results are shown in Table 1 below.

O:\9I\9 II 90*930218. DOC -15- 1278508 Table 1 Heat transfer efficiency comparison test Cooling water temperature Cooling water flow kg/h Balance time wide S Input power Kw Input heat Kcal Cooling water heat absorption Kcal System thermal efficiency % Ambient temperature Inlet temperature Outlet temperature Water medium 18.5〇C 17°C 32.239〇C 77.42 1800 3.146 1352.54 594.72 43.75 Medium of the invention 19°C 18.5〇C 58.6〇C 42.65 1200 2.256 646.604 560.988 87.68 The results show that the medium of the invention is water The heat transfer efficiency of the medium is much higher, which fully proves that the latent heat of vaporization of the medium of the present invention is large. As a result of the dielectric aging test, no end overcooling or low temperature occurred after 43200 hours of continuous heating, which proved that the medium of the present invention did not age. At the same time, the amount of medium loss was measured. The weight of the medium before and after heating was only 0.50 g. However, the amount of liquid flowing into the weighing bottle after evaporating the residual medium in the furnace body and the pipe and cooling the water was 〇49 g, indicating that the loss was almost Equal to zero. Corruption test results: 5 tests are size nut, steel plate, seamed steel pipe and seamless steel pipe. The results of soaking are as follows: Table 2: Table 2 Corrosion weight loss sample before soaking weight g After soaking weight g 1 30.114 30.1110 2 60.1156 60.1151 3 54.1324 54.1316 4 465.6876 365.6870 5 369.6121 369.6116 In addition, the X-ray flaw detector detects the furnace body and the pipe before and after heating. O:\91\91190-930218.DOC -16-1278508 Wall' found no metal phase Any change is sufficient to demonstrate that the inventive media is not corrosive. The heat transfer medium of the present invention can be used in the field of heating, in particular in the field of heating water media. , 'Because the heat transfer medium of the invention has large latent heat of vaporization, good heat conduction efficiency, fast heat transfer rate, no scaling, no auxiliary power (such as chestnut), no auxiliary equipment (such as water damage), and the system is not afraid; (Winter can be stopped at any time, start at any time), there are ^ 腐 姓 surname n, can greatly save energy and greatly reduce the operating costs of the system. In addition, the heat transfer medium of the present invention also exhibits excellent characteristics in the fields of heat exchange (steam_steam, steam-water, water_water), heat dissipation, etc., especially the viscosity, surface tension and thermal conductivity of the medium are within a certain range. It is adjustable inside, so it shows the advantage of far more than the general medium in the heat dissipation of the capillary structure and the heat exchanger. At the same time, the medium is non-toxic, odorless, non-volatile, non-flammable, non-explosive, safe and reliable to use. The invention has been described in detail above, and it is obvious that those skilled in the art can make various modifications and changes without departing from the spirit and scope of the invention.

O:\91\91190-930218.DOC -17-

Claims (1)

gDi Qiao|3K) Patent Application No. 3352——10^Applicable Patent Range Replacement (August 95) Pick up and apply for a patent garden: i•-type heat transfer medium' includes an aqueous solution of _ or more kinds of salts, Wherein at least one salt is a complex formed from one or more metal ions selected from the group consisting of copper 'silver, gold and zinc with an organic & C or inorganic acid, the complex optionally comprising ammonia' The pH of the heat transfer medium is 6-1 0. 2. According to the scope of the patent application! The heat transfer medium of the item, wherein the heat transfer medium has a pH of 7. 3. The heat transfer medium according to the ninth aspect of the invention, wherein the salt comprises a salt of an inorganic acid and/or an organic acid with an alkali metal or an alkaline earth metal. 4. The heat transfer medium according to claim 2, 2 or 3, wherein the inorganic acid comprises hydrochloric acid, sulfuric acid, money, nitric acid or a mixture thereof; the organic acid comprises humic acid or substituted or unsubstituted c 〗 _ c 6 mono or polyacid or a mixture thereof. 5. The heat transfer medium according to claim 4, wherein the inorganic acid comprises hydrochloric acid or phosphoric acid, and the organic acid comprises humic acid. 6. A heat transfer medium according to claim 2, 2 or 3, wherein the salt is present in an amount of at least 0.5% by weight and at most not more than 4% by weight. . 7. The heat transfer medium according to item 丨, 2 or 3 of the patent application, including copper ions, ammonium ions, zinc ions, sodium ions, gas ions, nitrate ions and water, the total salt amount being l_25 wt0 / 〇. 8. According to the patent application scope, item 2, 2 or 3 of the heat transfer medium, including steel ions, zinc ions, sodium ions, humate ions, nitrate ions, chloride ions and water 'total salt amount is 1-1 5 wt%. 9. A method of preparing a heat transfer medium comprising: dissolving one or more OAQlVQiinA 丨^1278508 salts in water to form at least one yttrium, formed from metal ions and/or inorganic acids selected from the group consisting of steel, silver, gold and zinc The complex, the complex 玎 selectively comprises ammonia's enthalpy of the heat transfer medium to 6-10. 10. According to the method of applying for a patent Fan Yuanchu, the 9th method of the garden, which comprises formulating the pH of the heat transfer medium to 7. The method according to claim 9 or 10, wherein the metal salt further comprises a salt of an inorganic and/or organic acid with an alkali metal and/or an alkaline earth metal. The method of claim 9 or claim 1, wherein the inorganic acid comprises hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid or a mixture thereof; the organic acid comprises a humic acid or a substituted or unsubstituted element or A polybasic acid or a mixture thereof. 13. The method of claim 12, wherein the inorganic acid comprises hydrochloric acid or acid and the organic acid comprises humic acid. 14. The method according to claim 9 or 10 wherein the salt has a content of at least 0.5% by weight and at most 40% by weight. 15. A heat transfer device in which a heat transfer medium according to item 1 of the patent application is used. -2- O:\91\9119O-95O803.DOC