KR101061837B1 - Antifreeze composition of fuel cell drive device - Google Patents

Abstract

The present invention relates to an antifreeze liquid composition for a fuel cell vehicle, wherein the composition comprises a trimethylglycine. By including trimethylglycine, it maintains an electric conductivity of 50 kW / cm or less to be equal to or higher than the freezing temperature of the conventional antifreeze liquid composition and to prevent a short circuit caused by an increase in the conductivity value that occurs during long-term operation of the fuel cell vehicle driving apparatus. . In addition, the pH decrease indicating the acidification rate of the antifreeze composition of the present invention is much slower than the antifreeze without addition of the trimethylglycine. Therefore, the antifreeze liquid composition of the present invention can be used for cooling water for a cooling system of a fuel cell drive device having an electrical conductivity of 50 kW / cm or less without being frozen in winter.

Antifreeze, Fuel Cell, Trimethylglycine, Alkylene Glycol

Description

Composition of Antifreezing Liquid for Cooling Systems in Fuel-Cell Drives

The present invention relates to an antifreeze liquid composition for a fuel cell drive device, wherein the composition comprises trimethylglycine.

Fuel cells generate electricity by using an electrochemical reaction between hydrogen and oxygen, and heat is incidentally generated. For example, in order to apply fuel cells to automobiles, several tens of kW stacks are being developed, and as the capacity of fuel cells increases, the amount of heat generated per unit volume increases, and the importance of cooling the stacks is increasing.

In order to obtain the required electrical output from the polymer electrolyte fuel cell, it is composed of a cell stack in which several cells are connected in series. In order to cool the generated heat, the coolant must have high electrical resistance, excellent insulation and cooling performance.

Cooling water for fuel cell vehicles should be non-conductive with good electrical insulation to protect the fuel cell system from short circuits and prevent electrical risks, and freeze below -30 ° C to allow cold start in winter or in cold weather. Should not be.

In the case of the existing coolant for internal combustion engine, organic or inorganic additives are used at the same time, the electrical conductivity is about 500 mW / cm or more and the electrical conductivity is high, which is not suitable for cooling water for fuel cell vehicles.

If a fuel cell system is used as a coolant for an internal combustion engine, the current generated in the stack causes ionization of the additive of the existing coolant to prevent a fatal defect in the fuel cell system by blocking the separator flow path in the stack due to an increase in conductivity and precipitation. Because it can cause.

Meanwhile, deionized water (DI-Water), which has been frequently used in the initial development of fuel cell system cooling water, has high electrical resistance, excellent electrical insulation, and excellent cooling performance. However, there are disadvantages of freezing below 0 ° C, problems of cold start of fuel cell vehicles, and pollution of ionic materials in fuel cell system, which are easily contaminated.

In addition, as a result of checking the cooling system for fuel cell vehicles to evaluate the influence of components used in fuel cell vehicles that come into contact with the fuel cell floating coolant, it can be classified into two types, two-way cooling and one-way cooling. It became.

As can be seen in Figure 1, looking at the configuration of the dual-cooling system, alkylene glycol was used to cool the stack and distilled water to cool the stack, and a double heat exchange (IHEX) device was used for heat exchange. In this system, Rapid Thaw Accumulator (RTA) was applied to prevent freezing of the distilled water used to cool the stack, and the whole system is not simple and complicated because a cooling water supply / drainage system is required.

In addition, as can be seen in Figure 2, when looking at the configuration of the one-way cooling system has the advantage of simplifying the system because the floating coolant is composed of one loop to cool the stack and the radiator at the same time, but the cooling water with the various components in the fuel cell system Due to the contact, ions in the parts are eluted with the cooling water, and the conductivity increases quickly.

Due to these problems, interest in fuel cell coolant that does not freeze in winter and has excellent electrical insulation has increased, and alkylene glycols such as monoethylene glycol and monopropyl glycol, which are the main base materials of the coolant being used for the internal combustion engine, are applied. have.

Throughout this specification many patent documents are referenced and their citations are indicated. The disclosures of the cited patent documents are incorporated by reference herein in their entirety, and the level of the technical field to which the present invention belongs and the contents of the present invention are more clearly described.

The present inventors have tried to develop an antifreeze liquid composition for a fuel cell vehicle having excellent electrical insulation without freezing in winter. As a result, when trimethylglycine is included in the alkylene glycol included in the conventional fuel cell vehicle antifreeze liquid composition, the freezing prevention function is equal to or higher and suppresses the increase in the electric conductivity value, which is an important characteristic of the fuel cell vehicle antifreeze solution. The present invention was completed by confirming that it had an effect.

Accordingly, an object of the present invention is to provide an antifreeze liquid composition for a fuel cell vehicle.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention, claims and drawings.

According to an aspect of the present invention, the present invention provides a fuel cell vehicle antifreeze liquid composition, wherein the composition comprises a trimethyl glycine antifreeze liquid composition for a fuel cell vehicle.

The present inventors have tried to develop an antifreeze liquid composition for a fuel cell vehicle having excellent electrical insulation without freezing in winter. As a result, when trimethylglycine is included in the alkylene glycol included in the conventional fuel cell vehicle antifreeze composition, the freeze protection function is equal to or higher and suppresses an increase in the electrical conductivity value, which is an important characteristic of the fuel cell vehicle antifreeze solution. It was confirmed to have an effect.

The trimethylglycines used in the compositions of the present invention are natural quaternary ammonium compounds, and they are generally anhydrides or monohydrates and are generally betaine, trimethylammonioacetate, 1-carboxy-N, N, N-trimethylmethanealuminum inert salts. And glycinebetaine. The molecular formula of trimethyl glycine is C ₅ H ₁₁ NO _2, the general formula ^{_{(CH 3) 3 N + -CH}} 2 COO - is a compound having the structure. The trimethylglycine used in the composition of the present invention can be artificially synthesized as well as extracted from sugar beet or wolfberry which is a natural source.

In addition, the trimethylglycine used in the present invention is not only a compound of the formula, but also a derivative of the formula obtained through various substituents and substituent coupling reactions known in the art using the structure of the formula as a nucleus. Included in For example, hydrogen bound to carbon located between nitrogen and carboxyl groups in the structure of trimethylglycine may exert the same or similar efficacy as trimethylglycine even when substituted with hydroxyl, halo, nitro or alkyl groups having 1-3 carbon atoms. In some cases, such substituted derivatives are included in the scope of the present invention.

According to a preferred embodiment of the present invention, trimethylglycine used in the present invention is included at 0.02-6% by weight based on the total weight of the composition, more preferably 0.1-3% by weight, most preferably 0.1-2 Weight percent. When trimethylglycine deviates from 0.02-6% by weight, there is a problem in that the effect of keeping the electrical conductivity low is reduced.

The greatest feature of the present invention is that the antifreeze liquid composition of the present invention comprising trimethylglycine is equal to or higher than the freezing temperature of the conventional antifreeze liquid composition, and maintains an electrical conductivity of 50 kW / cm or less even during long-term operation of the fuel cell vehicle driving apparatus. Is that.

According to another preferred embodiment of the present invention, the composition of the present invention further comprises deionized water and alkylene glycol.

According to a more preferred embodiment of the present invention, the composition of the present invention comprises 35-65% by weight deionized water, 30-60% by weight alkylene glycol and 0.02-6% by weight trimethylglycine based on the total weight of the composition And even more preferably, 40-60% by weight of deionized water, 39.9-57% by weight of alkylene glycol and 0.1-3% by weight of trimethylglycine, most preferably 45-55% by weight of deionized water, 44.9-alkylene glycol. 53 weight percent and 0.1-2 weight percent trimethylglycine.

As the deionized water used in the composition of the present invention, deionized water, pure distilled water or water distilled twice by ion exchange can be used.

According to another preferred embodiment of the present invention, the alkylene glycol used in the composition of the present invention is a group consisting of monoethylene glycol, monofloethylene glycol, diethylene glycol, dipropylene glycol, glycerin, triethylene glycol and tripropylene glycol It is selected from, and more preferably, monoethylene glycol, monofloethylene glycol, diethylene glycol, dipropylene glycol or glycerin, most preferably monoethylene glycol or monoflophylene glycol.

According to a preferred embodiment of the present invention, the composition of the present invention is used for cooling water for a cooling system of a fuel cell drive device having an electrical conductivity of 50 kW / cm or less. More preferably, it is used for the cooling water for the cooling system of a fuel cell drive device whose electrical conductivity is 40 kW / cm, most preferably 30 kW / cm or less. This low electrical conductivity is maintained even in the long term operation of the fuel cell drive.

The pH reduction of the antifreeze composition of the present invention is much slower than the antifreeze solution without the trimethylglycine.

The antifreeze composition of the present invention may include a pH adjusting agent, a dye, an antifoaming agent or a corrosion inhibitor. The corrosion inhibitor may include various corrosion inhibitors known in the art within a range that does not affect the electrical conductivity of the antifreeze liquid composition of the present invention. For example, carboxylate, phosphate, nitrate, nitrite, molybdate, tungstate, borate, silicate, sulfate, sulfite, carbonate, amine salt, triazole, thiazole and the like.

As described in detail above, the present invention provides an antifreeze liquid composition for a fuel cell vehicle, wherein the composition includes a trimethylglycine. By containing trimethylglycine, the electrical conductivity of 50 kW / cm or less is maintained to be equal to or higher than the freezing temperature of the conventional antifreeze liquid composition and to prevent a short circuit caused by an increase in the conductivity value that occurs during long-term operation of the fuel cell vehicle driving apparatus. . In addition, the pH decrease indicating the acidification rate of the antifreeze composition of the present invention is much slower than the antifreeze without addition of the trimethylglycine. Therefore, the antifreeze liquid composition of the present invention can be used for cooling water for a cooling system of a fuel cell drive device having an electrical conductivity of 50 kW / cm or less without being frozen in winter.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention in more detail, and the scope of the present invention is not limited by these examples according to the gist of the present invention to those skilled in the art to which the present invention pertains. Will be self explanatory.

Example

Example  1: Preparation of Anticoolant Composition

The antifreeze composition was prepared by weighing the contents of the ingredients shown in Table 1 below on a scale and adding them to DI water and stirring until a uniform solution without residues was obtained. Deionized water was used as deionized water from which ions were removed in an ultrapure water production system. Glycols were ethylene glycol or propylene glycol of DOW Chemical, and trimethylglycine was 99.9% pure product of AsahiKasei of Japan.

Composition of Anticoolant Composition Ingredients (% by weight) compare
Composition 1 compare
Composition 2 compare
Composition 3 compare
Composition 4 practice
Composition 1 practice
Composition 2 practice
Composition 3 Deionized water 100 50 50 50 50 50 50 Alkylene glycol Monoethylene
Glycol (MEG) - 50 - 20 49.5 - - Propylene
Glycol (PG) - - 50 - - 49.5 48 Trimethylglycine - - - 30 0.5 0.5 2 Sum 100 100 100 100 100 100 100

Example  2: Measurement of freezing temperature and electrical conductivity of antifreeze composition

The freezing temperature of Table 2 was measured according to ASTM D1177, and the electrical conductivity was measured by using a conductivity meter of Thermo orion 162A to measure initial electrical conductivity of each sample.

Measurement item compare
Composition 2 compare
Composition 3 compare
Composition 4 practice
Composition 3 Freezing Temperature (℃) -35 -34 -35 -35 Electrical conductivity before test (㎲ / ㎝) 0.60 0.40 6.84 1.05

As can be seen in Table 2, it can be seen that the freezing temperature of trimethylglycine aqueous solution (comparative composition 4) is similar to the freezing temperature (comparative compositions 2 and 3) of the aqueous glycol solution. This means that even if trimethylglycine is added to alkylene glycol, the performance of freezing temperature does not occur.

In addition, the electrical conductivity of the trimethylglycine aqueous solution (comparative composition 4) was about 13 times higher than that of the alkylene glycol aqueous solution (comparative compositions 2 and 3). I could confirm it.

However, when trimethylglycine is added to the alkylene glycol (Example 3), the electrical conductivity value of the cooling water is kept lower for a long time than when only alkylene glycol is used as the cooling water for the fuel cell (Comparative Compositions 2 and 3). This is of particular interest in the automotive sector as it has a close relationship with the replacement cycle of the coolant for fuel cells.

Therefore, the antifreeze liquid composition of the present invention containing alkylene glycol or a derivative thereof and containing trimethylglycine can be used for cooling water for a cooling system of a fuel cell drive device having an electrical conductivity of 50 kW / cm or less.

Example  3: Sedimentation Test of Antifreeze Compositions on Non-Metal and Metallic Materials

Referring to the cooling water paths of FIGS. 1 and 2, the parts in contact with the cooling water in the fuel cell vehicle system may be largely divided into a non-metal material such as a separator in a stack and a radiator metal material of aluminum. The deposition test of the antifreeze liquid composition on non-metals and metals, which are parts in use in the fuel cell system, was carried out to measure the electrical conductivity and pH change of the antifreeze liquid.

A certain amount of parts to be deposited in a polypropylene (PP) airtight container was deposited in 150 ml of antifreeze solution, plugged, and left in a 90 ° C oven for a long time. The electrical conductivity and pH of the antifreeze solution were changed over time. It was measured using a conductivity meter of Thermo orion 162A and a pH meter of Thermo orion 720A ⁺ .

Among the fuel cell system components, a graphite separator (2 cm x 2 cm) and an Al 3000 series aluminum radiator tube material (2 cm x 2 cm) were used for the deposition test.

Sedimentation test of the antifreeze composition on the separator Metric compare
Composition 1 compare
Composition 2 compare
Composition 3 practice
Composition 1 practice
Composition 2 practice
Composition 3 Electricity
conductivity
ms / cm Before the test 0.70 0.60 0.40 0.70 0.48 1.05 168 h 1.12 2.75 1.23 0.95 0.78 1.96 336 h 1.42 5.87 1.68 1.00 0.94 2.00 500 h 5.10 7.58 3.95 1.62 1.12 2.12 1000 h 8.98 10.20 6.58 2.83 1.57 2.64 2000 h 14.68 12.42 9.42 3.01 2.38 3.25 3000 h 21.83 18.21 13.32 5.37 3.67 4.25 pH
change Before the test 5.59 6.05 6.12 6.15 6.16 6.37 After the test 4.05 3.27 4.14 5.32 5.63 5.65 After the test
State of the sum transparent Dark Yellow Transparent transparent Light yellow transparent transparent transparent

As can be seen in Table 3, the antifreeze liquid compositions (Examples 1 to 3) of the present invention for the separator plate of the non-metallic part of the fuel cell system are Comparative Compositions 1 (deionized water) and 3 (deionized water and MEG). It can be seen that the electrical conductivity is kept very low rather than. In addition, compared to Comparative Composition 3 (deionized water and PG), the composition (Examples 2 and 3) of the present invention compared trimethylglycine by adding trimethylglycine to alkylene glycol, so that the change in electric conductivity value compared to deposition time did not add trimethylglycine. It can be seen that the electrical conductivity value is significantly lower than the composition 3. In addition, it can be seen that the embodiment composition of the present invention does not have a large pH change compared to the comparative composition.

Immersion Test of Antifreeze Composition on Al 3000 Series Radiator Tube Material Metric compare
Composition 1 compare
Composition 2 compare
Composition 3 practice
Composition 1 practice
Composition 2 practice
Composition 3 Electricity
conductivity
ms / cm Before the test 0.70 0.60 0.40 0.70 0.48 1.05 168 h 4.56 4.14 1.92 1.33 0.98 1.88 336 h 11.08 7.23 5.13 2.28 1.05 2.74 500 h 17.72 10.54 7.16 2.32 1.54 3.90 1000 h 25.13 12.78 11.99 4.64 2.92 6.88 2000 h 38.95 20.12 18.03 7.54 5.25 8.54 3000 h 42.57 29.31 25.37 9.85 7.34 10.85 Appearance of aluminum test specimen after test discoloration discoloration discoloration discoloration discoloration discoloration pH change Before the test 5.57 4.45 6.12 6.15 6.16 6.37 After the test 4.16 2.71 4.21 5.10 5.21 5.25 Separator
% Change in weight -0.09 -0.08 -0.09 -0.04 -0.03 -0.04 After the test
State of the sum transparent transparent transparent transparent transparent transparent

As can be seen in Table 4, for the radiator tube material, which is a metal component of the fuel cell system, the antifreeze composition (Examples 1 to 3) of the present invention is Comparative Compositions 1 (deionized water) and 3 (deionized water and It can be seen that the electrical conductivity is kept very low than MEG). In addition, compared to Comparative Composition 3 (deionized water and PG), the composition (Examples 2 and 3) of the present invention compared trimethylglycine by adding trimethylglycine to alkylene glycol, so that the change in electric conductivity value compared to deposition time did not add trimethylglycine. It can be seen that the electrical conductivity value is significantly lower than the composition 3. In addition, it was found that the pH change of the embodiment composition of the present invention was not as large as that of the comparative composition, and the embodiment composition of the present invention did not change the state of the liquid after the test and the appearance of the aluminum test specimen as in the comparative composition. On the other hand, in the weight change rate of the separator, it can be seen that the embodiment composition of the present invention has a smaller change rate than the comparative composition and is superior.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.

1 shows a system configuration of a binary cooling method of a cooling system for a fuel cell vehicle.

2 shows a system configuration of a one-way cooling system of the cooling system for fuel cell vehicles.

Claims (6)

The antifreeze liquid composition for a fuel cell vehicle, wherein the composition comprises trimethylglycine, deionized water, and alkylene glycol. delete The anti-coolant composition of claim 1, wherein the trimethylglycine is included in an amount of 0.02-6% by weight based on the total weight of the composition. The anti-coolant according to claim 1, wherein the composition comprises 35-65 wt% of deionized water, 30-60 wt% of alkylene glycol, and 0.02-6 wt% of trimethylglycine based on the total weight of the composition. Composition. The antifreeze liquid composition according to claim 1, wherein the alkylene glycol is selected from the group consisting of monoethylene glycol, monoflolene glycol, diethylene glycol, dipropylene glycol, glycerin, triethylene glycol and tripropylene glycol. . The antifreeze liquid composition according to claim 1, wherein the composition is used for cooling water for a cooling system of a fuel cell drive device having an electrical conductivity of 50 kW / cm or less.

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