阅读说明：本技术 一种低电导率燃料电池系统用冷却液及其制备方法 (Cooling liquid for low-conductivity fuel cell system and preparation method thereof ) 是由 李立春 于 2020-04-30 设计创作，主要内容包括：本发明属于冷却液技术领域,具体涉及一种燃料电池系统冷却液及其制备方法,更为具体的涉及一种能有效防止燃料电池冷却系统腐蚀的低电导率冷却液。本发明所述冷却液按照重量百分比计算,包括0.5～1％脲嘧啶、22.4-55.58％乙二醇、1～2％有机缓蚀剂、2～3％乳糖醇、100～300ppm的消泡剂,余量为超纯水。本发明中在保证较低电导率的情况下对添加剂进行了筛选,使制备出的冷却液具有使用性能稳定,防腐效果优越的特点,缓蚀率为70.23％,90天后冷却液的电导率依然低于3μS/cm。(The invention belongs to the technical field of cooling liquid, particularly relates to cooling liquid for a fuel cell system and a preparation method thereof, and more particularly relates to low-conductivity cooling liquid capable of effectively preventing corrosion of the cooling system of the fuel cell. The cooling liquid comprises, by weight, 0.5-1% of uracil, 22.4-55.58% of ethylene glycol, 1-2% of an organic corrosion inhibitor, 2-3% of lactitol, 100-300 ppm of an antifoaming agent, and the balance of ultrapure water. In the invention, the additives are screened under the condition of ensuring lower conductivity, so that the prepared cooling liquid has the characteristics of stable service performance and excellent corrosion prevention effect, the corrosion inhibition rate is 70.23%, and the conductivity of the cooling liquid is still lower than 3 mu S/cm after 90 days.)

1. A coolant for a low conductivity fuel cell system, said coolant comprising: uracil, ultrapure water, ethylene glycol and defoaming agent, its characterized in that: organic corrosion inhibitors and lactitol are also present.

2. The cooling liquid for a low-conductivity fuel cell system according to claim 1, characterized in that: the organic corrosion inhibitor is any one of benzimidazole, mannitol, glycerol or benzotriazole.

3. The cooling liquid for a low-conductivity fuel cell system according to claim 2, characterized in that: the organic corrosion inhibitor is benzotriazole.

4. The cooling liquid for a low-conductivity fuel cell system according to claim 1, characterized in that: the defoaming agent is a polyether defoaming agent, and the polyether defoaming agent is any one of GP type glycerol polyether, GPE type polyoxyethylene (polyoxypropylene) ether or PPG type polypropylene glycol.

5. The cooling liquid for a low-conductivity fuel cell system according to any one of claims 1 to 4, wherein: the cooling liquid comprises, by weight, 0.5-1% of uracil, 22.4-55.58% of ethylene glycol, 1-2% of an organic corrosion inhibitor, 2-3% of lactitol, 100-300 ppm of a defoaming agent, and the balance of ultrapure water.

6. The cooling liquid for a low-conductivity fuel cell system according to any one of claims 1 to 4, wherein: the cooling liquid comprises, by weight, 1% uracil, 45% ethylene glycol, 2% organic corrosion inhibitor, 2% lactitol, 300ppm defoamer and the balance ultrapure water.

7. A method for preparing a coolant for a low-conductivity fuel cell system according to claim 1, comprising the steps of:

1) adding ultrapure water into an additive preparation tank, stirring, adding uracil, and stirring to fully dissolve the uracil to obtain a solution of an additive A for later use;

2) adding ultrapure water into an additive preparation tank, starting stirring, adding the organic corrosion inhibitor, stirring to fully dissolve the organic corrosion inhibitor to obtain an additive B, and putting the additive B for later use;

3) adding ultrapure water into an additive preparation tank, stirring, adding lactitol, stirring to fully dissolve to obtain an additive C, and putting down for later use;

4) and adding ethylene glycol into the cooling liquid preparation tank, starting stirring, sequentially adding the additive A, the additive B and the additive C, stirring for 30 minutes, adding the non-ionic defoaming agent dissolved by ultrapure water, and uniformly stirring to obtain the water-based cooling liquid.

Technical Field

The invention belongs to the technical field of cooling liquid, and particularly relates to cooling liquid for a fuel cell system and a preparation method thereof.

Background

The fuel cell cooling liquid is mainly used for a fuel cell cooling system and is used as a heat conduction medium of the cooling system to timely dissipate heat, so that the fuel cell is ensured to work at a proper temperature. At present, the cooling liquid sold in the market has higher conductivity and cannot meet the operation requirement of the fuel cell, part of fuel cell manufacturers use ethylene glycol aqueous solution as the cooling liquid directly, although the cooling liquid can play a certain role in a short time, flocculation is generated along with the operation of a system to block a cooling water channel of the fuel cell, and corrosion is generated to a cooling system.

The coolant used by the fuel cell cooling system needs lower conductivity to ensure the stable and safe operation of the system, the international famous fuel cell company Brad requires that the conductivity of the coolant for the system operation is below 5 mus/cm, and the common motor vehicle coolant basically has the conductivity above 2000 mus/cm and cannot meet the use requirement. At present, domestic fuel cell manufacturers use ethylene glycol aqueous solution, the solution can meet the requirement of lower conductivity at the initial stage of use, but the conductivity of the solution can be increased due to corrosion along with the operation of the system, and the ethylene glycol aqueous solution can be polymerized to form floccule after being heated to block a cooling water channel of the fuel cell system.

Aluminum alloys are often used in large numbers in cold plates and cooling channels of fuel cell cooling systems due to their light weight, good thermal conductivity, and certain corrosion resistance. Although the glycol coolant has low corrosivity, in the long-term use process, the aluminum alloy is often corroded to generate free aluminum ions, so that the conductivity of the coolant is increased, and meanwhile, the stability of a heat dissipation system is reduced due to the corrosion of a radiator pipeline, so that certain potential safety hazards exist.

Therefore, the development of the cooling liquid for the fuel cell system, which has low conductivity and corrosion inhibition function and is suitable for the aluminum alloy medium, has important significance.

Disclosure of Invention

The invention aims to overcome the defects that the conductivity of the fuel cell cooling liquid in the current market is higher at the initial stage or the conductivity is obviously increased along with the use process, and provides the cooling liquid for the low-conductivity fuel cell system.

Another object of the present invention is to solve the problem of corrosion of the aluminum alloy cold plates and cooling channels of the fuel cell cooling system caused by the conventional fuel cell coolant during use.

According to a first aspect of the present invention, there is provided a coolant for a low conductivity fuel cell system, the coolant comprising: uracil, ultrapure water, ethylene glycol, an organic corrosion inhibitor, lactitol and a defoaming agent.

Preferably, the organic corrosion inhibitor is benzimidazole, mannitol, glycerol or benzotriazole; further preferably benzotriazole.

Preferably, the defoamer is a polyether defoamer, and the polyether defoamer is any one of GP type glycerol polyether, GPE type polyoxyethylene (polyoxypropylene) ether or PPG type polypropylene glycol.

Preferably, the cooling liquid comprises, by weight, 0.5-1% of uracil, 22.4-55.58% of ethylene glycol, 1-2% of an organic corrosion inhibitor, 2-3% of lactitol, 100-300 ppm of an antifoaming agent, and the balance of ultrapure water; further preferably 1% uracil, 45% ethylene glycol, 2% organic corrosion inhibitor, 2% lactitol, 300ppm defoamer, the balance ultrapure water;

when the formula is preliminarily screened in the early stage, in order to solve the problem that the cooling liquid corrodes an aluminum alloy cold plate and a cooling channel of a cooling system, the corrosion inhibitor is introduced, but the introduction of the corrosion inhibitor inevitably leads to the increase of the conductivity of the cooling liquid, so in order to avoid the increase of the conductivity of the cooling liquid caused by the introduction of the corrosion inhibitor, the organic matter with low conductivity is adopted as the corrosion inhibitor, particularly benzotriazole, so that the prepared cooling liquid can obtain low conductivity at the initial stage of preparation and can play a role in slow release.

In addition, in order to improve the stability of the prepared cooling liquid (glycol/water cooling liquid may have floc during use), the present inventors have surprisingly found that when lactitol is added as a stabilizer, the prepared cooling liquid can be stably operated under the condition of lower conductivity without generating floc, probably because lactitol can chelate metal ions by chelating.

According to another aspect of the present invention, there is provided a method for preparing a coolant for a low-conductivity fuel cell system, comprising the steps of:

1) adding ultrapure water into an additive preparation tank, stirring, adding uracil, and stirring to fully dissolve the uracil to obtain a solution of an additive A for later use;

2) adding ultrapure water into an additive preparation tank, starting stirring, adding the organic corrosion inhibitor, stirring to fully dissolve the organic corrosion inhibitor to obtain an additive B, and putting the additive B for later use;

3) adding ultrapure water into an additive preparation tank, stirring, adding lactitol, stirring to fully dissolve to obtain an additive C, and putting down for later use;

4) and adding ethylene glycol into the cooling liquid preparation tank, starting stirring, sequentially adding the additive A, the additive B and the additive C, stirring for 30 minutes, adding the non-ionic defoaming agent dissolved by ultrapure water, and uniformly stirring to obtain the water-based cooling liquid.

Compared with the prior art, the invention has the following advantages:

1) according to the invention, the organic corrosion inhibitor is added into the fuel cell cooling liquid, so that the problem that the aluminum alloy cold plate and the cooling channel of the fuel cell cooling system are corroded due to corrosion of the fuel cell cooling liquid is solved; benzotriazole is the best corrosion inhibitor of the fuel cell cooling liquid, the corrosion inhibition rate obtained by a weight loss experiment is 70.23%, and the conductivity of the cooling liquid is still lower than 3 muS/cm after 90 days.

2) According to the invention, the lactitol is added into the fuel cell cooling liquid, and the defect of poor stability of the cooling liquid is solved by introducing the lactitol, so that the prepared cooling liquid can stably run under the condition of lower conductivity, and no floccule appears in the use process.

3) The cooling liquid prepared by the invention has excellent comprehensive performance, namely, the initial conductivity is low, and the lower conductivity can be kept for a long time, so that the cooling system of the fuel cell can stably operate in a lower conductivity state.

Drawings

FIG. 1 is a plot of conductivity versus time for coolants prepared with the addition of different corrosion inhibitor solutions;

FIG. 2 is a plot of the conductivity over time for the cooling fluid prepared in example 2;

FIG. 3 is a corrosion resistance simulation test chart of the coolant prepared in example 2;

fig. 4 is a plot of conductivity versus time for a conventional ethylene glycol/water coolant.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention.

And (3) conductivity test: and (3) measuring the conductivity of the sample by using a conductivity meter (DDS-307, Johan instruments, Guangzhou), and recording the change condition of the conductivity of the sample.

The corrosion rate and the corrosion inhibition rate are that ADC12 aluminum alloy with the size of 50mm × 25mm × 4mm is adopted as a sample of a weightlessness experiment, firstly, grinding and polishing, cleaning and drying are carried out, then, the sample is respectively put into blank solution with the temperature of 80 ℃ and cooling liquid added with different corrosion inhibitors for immersion experiment for 168 hours, three parallel samples are arranged in each group of experiment, after the experiment is finished, a test piece is taken out, the aluminum sheet is immersed in concentrated nitric acid for 1-5 minutes to remove corrosive substances after being corroded as shown in figure 2-2, the aluminum sheet is taken out, cleaned and dried, and then weighed again by an electronic balance, the corrosion is evaluated according to the mass change before and after the test piece test, and the corrosion rate V-of each time can be calculated by a formula (2-:

V^-＝(W₀-W₁)/S·t (2-1)

in the formula: v^-Is the metal corrosion rate (g/m)^-2·h^-1)；W₀Mass (g) before metal corrosion; w₁The quality of the metal after the corrosion products are removed after the metal is corroded; s is the surface area of the metal; t is the time of etching (h).

The corrosion inhibition rate η can be calculated by the formula (2-2):

in the formula: v^-0、V^-1 is the corrosion rate without and with the addition of the corrosion inhibitor.