WO2005105948A1

WO2005105948A1 - Heating medium composition

Info

Publication number: WO2005105948A1
Application number: PCT/JP2004/006220
Authority: WO
Inventors: Hiroshi Egawa; Nobuyuki Kaga
Original assignee: Shishiai-Kabushikigaisha
Priority date: 2004-04-28
Filing date: 2004-04-28
Publication date: 2005-11-10
Also published as: JPWO2005105948A1

Abstract

A heating medium composition for use in cooling systems for an internal combustion engine and other engines and in cooling systems for a solar system, floor heating system, air conditioning equipment and fuel cell. In particular, a heating medium composition wherein the oxidation of contained base can be effectively inhibited so as to suppress the drop of pH value and rise of conductivity of the heating medium composition. This heating medium composition is characterized by containing a carbon allotrope or derivative thereof.

Description

l¾Itoda »Heat transfer medium technical field

The present invention relates to a heating medium composition applied to, for example, a cooling system of an internal combustion engine such as an engine, a cooling system of a fuel cell, a solar system, a floor heating system, an air conditioner, and the like. The present invention relates to a heat medium composition capable of suppressing a decrease in pH value and an increase in electrical conductivity by suppressing the heat medium composition effectively. Background art

Conventionally, heat medium compositions applied to cooling systems for internal combustion engines such as engines, solar systems, floor heating systems, air conditioning equipment, etc. have been based on glycols and alcohols, etc. The addition of is known. However, in such a heating medium composition, the glycols and alcohols used as a base are exposed to a high-temperature and high-pressure atmosphere during use, and therefore oxidize slightly with the passage of time. Changes to degradation products such as formic acid. Therefore, over a long period of use, the oxidation of the base in the heat medium composition further progresses, and accordingly, the pH value of the heat medium composition also gradually decreases, and the cooling of the internal combustion engine such as an engine is cooled. Metals that make up the grid, solar system, floor heating system, and air conditioning equipment could be corroded. Therefore, suppression of oxidation of the base in the heat medium composition has been an important technical problem to be overcome in the heat medium composition used for these applications. On the other hand, fuel cells have unique technical issues. That is, a fuel cell is generally configured as a stack having a structure in which a large number of single cells, which are power generation units, are stacked. Since heat is generated from this stack during power generation, a coolant passage is provided during the separation to cool the stack, and the coolant flows through the coolant passage to cool the stack. . For this reason, if the electrical conductivity of the coolant of the fuel cell is high, the electricity generated in the stack performing power generation flows to the coolant side, and the power generated in the fuel cell decreases. Will be. Therefore, pure water having low conductivity, in other words, pure water having high electrical insulation, has been used for the cooling liquid of the conventional fuel cell. However, when considering, for example, fuel cells for automobiles and fuel cells for home cogeneration systems, the coolant will drop to ambient temperature when not in operation. In particular, if there is a possibility of use below the freezing point, pure water will freeze. Pure oil volume expansion may damage the separator and damage the fuel cell performance. Under these circumstances, it is conceivable to use darichols or alcohols for the purpose of antifreezing in the coolant for fuel cells. However, when used as a coolant for a fuel cell, glycols and alcohols oxidize during operation of the fuel cell to produce a small amount of ionic substances. Therefore, if used for a long period of time, the amount of ionic substances in the coolant will also increase, which may lead to a situation where low conductivity cannot be maintained. In order to eliminate such problems, an ion-exchange resin is placed in the cooling system path of the fuel cell to remove ionic substances in the coolant and suppress the rise in the conductivity of the coolant. Conceivable. However, in this case, the ion-exchange resin is used to remove the ionic substances generated by oxidation of the base material, and the ion-exchange amount of the ion-exchange resin quickly decreases, and the exchange life is significantly reduced. There was a technical challenge to do so. The present invention has been made in view of such technical problems, and a heat medium composition capable of suppressing a decrease in pH value and an increase in conductivity by effectively suppressing oxidation of a base. The purpose is to provide. Disclosure of the invention

The heat medium composition of the present invention (hereinafter, simply referred to as a composition) is characterized by containing a carbon isotope or a derivative thereof in a base. As the base, those having antifreeze properties are desirable, and specifically, those composed of one or a mixture of two or more selected from water, alcohols, daricols and dalicol ethers are desirable. Examples of alcohols include those composed of one or a mixture of two or more selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol. . Glycols include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, and hexylene glycol. And mixtures of two or more selected from the group consisting of: Glycol ethers include, for example, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol Chole monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, Examples thereof include those composed of one or a mixture of two or more selected from diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and tetraethylene glycol monobutyl ether. The composition of the present invention suppresses the oxidation of the base by including a carbon allotrope or a derivative thereof in the base, whereby the PH value of the composition caused by the oxidation of the base is reduced. The reduction and the increase in the conductivity are suppressed. Graphite, diamond, fullerene, and carbon nanotubes can be given as examples of the carbon allotrope exhibiting such effects. Among them, consisting of a closed hollow shell-like 5-membered ring and six-membered ring of the _{_{network, C 60, C 70, C}} 76, C 78, C 82, fullerene such as C _84, C _96, small within the structure of the fullerene bucky onion incorporating fullerene _{_{(C 6 Q @ C 24.}} @ C 5 40), hetero-fullerene incorporating metal within the structure of the hula one Ren (M @ Ceo) either 1. species or two or more of, It is preferable in that the oxidation of the base can be effectively suppressed, particularly C ₆ . And C ?. Fullerenes are more desirable in terms of availability, handling, and price. In addition, examples of the derivative of carbon allotrope include hydroxides, hydrides, fluorides, and bromides of carbon allotropes, and are particularly selected from hydroxides, hydrides, fluorides, and bromides of fullerenes. Species or two or more species are preferable in terms of availability, handling, and price. The content of the carbon allotrope or a derivative thereof is 0.0 It is desirably in the range of 0.1 to 10% by weight. When the content of the carbon allotrope or its derivative is smaller than the above range, a sufficient oxidation suppressing effect cannot be obtained, and when the content of the carbon allotrope or its derivative is larger than the above range, The effect of the increased amount cannot be obtained, which is uneconomical. The composition of the present invention may contain, for example, caustic alkali for adjusting pH, a dye, an antifoaming agent, a preservative, and the like, in addition to the above-mentioned base and carbon allotrope. Even when used in combination with mackerel, phosphate, nitrate, nitrite, molybdate, tungstate, borate, silicate, sulfate, sulfite, carboxylate, amine salt, triazole, etc. good. Example

Hereinafter, the composition of the present invention will be described in more detail with reference to Examples. Table 1 below shows, as a preferred embodiment of this composition, a base obtained by adding ethylene glycol for the purpose of imparting antifreeze to ion-exchanged water, and containing a fullerene hydroxide in the base ( Examples 1 and 2) and a comparative example (Comparative Example 1) consisting only of the base material of Example 1 were mentioned. In addition, nanom spectra HX10-S (manufactured by Frontier Carbon Co., Ltd.) was used as the hydroxylated fullerene in Table 1.

(Below)

table 1

* Hydroxyfullerene: nanom spectra HX10-S (Frontier Power Phone Co., Ltd.) Conductivity of each composition of Examples 1 and 2 and Comparative Example 1 shown in Table 1 above after the oxidation deterioration test The results were shown in Table 2. The oxidative deterioration test was performed on each of the above compositions at 100 ° C. for 33 hours.

(Hereinafter the margin) Table 2

From Table 2, the composition of Comparative Example 1 had an initial conductivity of 0 aS / cm, whereas the conductivity after the oxidation deterioration test was 80 S / cm, and the conductivity increased significantly. Was confirmed. In contrast, the initial conductivity of each of the compositions of Examples 1 and 2 was 2 iS / cm and 1 S / cm, whereas the conductivity after the oxidation deterioration test was 45 x S / cm and 55 S / cm, indicating that the increase in conductivity was suppressed in both cases. In addition, regarding the degradation products after the oxidative degradation test, in the case of the composition of the comparative example, after the degradation test, the content increased significantly to 14 tmol / l. In this case, the amount of degradation products after the test was only a slight increase of 5 imol / 1 and 8 substitution / 1, indicating that each of the compositions according to Examples 1 and 2 was effective in suppressing the degradation. confirmed. The invention's effect

The composition of the present invention effectively suppresses the oxidation of the base by including a carbon allotrope or a derivative thereof in the base, whereby the heat medium composition caused by the oxidation of the base is reduced. A decrease in pH value and an increase in conductivity can be suppressed.

Claims

Scope of Word

1. A heat carrier composition containing a carbon allotrope or a derivative thereof.

2. The heat carrier composition according to claim 1, wherein the base comprises one or a mixture of two or more selected from water, alcohols, glycols and dalicol ethers.

3. The heat carrier composition according to claim 1, wherein the carbon allotrope or a derivative thereof is contained in a proportion of 0.0001 to 10% by weight.

4. The heat carrier composition according to claim 1, wherein the carbon allotrope is fullerene.

5. The heat carrier composition according to claim 4, wherein the derivative of the carbon allotrope is one or more selected from hydroxide, hydride, fluoride, and bromide of fullerene.

6. The heat carrier composition according to any one of claims 1 to 5, further comprising at least one kind of a protective agent.

7. A coolant composition for a fuel cell stack, wherein the heat medium composition according to any one of claims 1 to 5 is used.