JPS6015663B2 - Endothermic liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid composition useful as a heat absorber for solar water heaters and heat collectors. An object of the present invention is to provide a liquid for absorbing solar heat that can be used as a solar heat absorbing liquid.

It is conventionally known to expose a black liquid to the sun's rays to absorb solar heat, and then use heat exchange to raise the temperature of ordinary tap water for use in domestic or industrial applications. As such liquid heat absorbers, black dyes dissolved in water or black pigments dispersed in water are used, but those using dyes are resistant to long-term light exposure. It is not practical due to poor stability. On the other hand, products using black pigments such as Chikara-Pump Lac have excellent stability against light, but when used for long periods, for example, Chikara-Pump Black dispersed in water with a dispersant may be used in water heaters. When tap water is passed through the pipes of a bamboo blind heater to absorb solar heat and then heated by a heat exchanger, the dispersed carbon black deposits on the inner surface of the pipes and the heat absorption rate etc. decreases. However, there is also the drawback that the dispersion stability decreases due to repeated temperature changes over a long period of time and the influence of sunlight, causing carbon black to precipitate and the performance as a moth heating element to be lost. Further, as a general problem, as the temperature rises due to heat absorption, the amount of heat emitted from the neck increases, so it is desired to suppress this heat radiation to some extent. As a result of intensive research to solve the above-mentioned drawbacks of conventional heat-absorbing liquids, the present inventors found that even if carbon black is used as a heat-absorbing black material, it is difficult to combine a specific dispersant and dispersion medium with paper. The present invention has been completed based on the finding that by using carbon black, and further by using carbon black in combination with a specific pigment, an endothermic liquid that overcomes the drawbacks of the above-mentioned prior art can be obtained. It is.

That is, the present invention provides a liquid for solar heat absorption consisting of a dispersion medium, a dispersant, and a heat absorber, in which the dispersion medium is ethylene glycol, propylene glycol, glycerin,
The dispersing agent is an aromatic sulfonic acid formalin condensate or a salt thereof, and the heat absorbing material is carbon black or carbon black and a metal oxide. This is a solar heating liquid characterized by being a mixture with a pigment.

To explain the present invention in more detail, the proportion of each component constituting the liquid composition of the present invention is such that the heat absorber is used in a proportion of about 0.001 to 1 part by weight in 10 parts by weight of the liquid composition, preferably The proportion is about 0.01 to 2 parts by weight, and if the amount is below the lower limit of this range, absorption of solar heat will be insufficient;
If the upper limit is exceeded, sunlight will not reach the interior of the liquid, resulting in insufficient heat absorption.

The dispersant is present in a proportion of about 0.001 to 2 parts by weight, preferably about 0.5 to 5 parts by weight; amounts below the lower limit of this range will reduce the dispersion stability of the heat absorber. On the other hand, if the upper limit is exceeded, the viscosity becomes too high and the efficiency of heat exchange decreases. The dispersing medium is used in a ratio of about 7 parts by weight or more, preferably about 9 parts by weight or more, with the remainder being the heat absorber and the remaining parts by weight of the dispersing agent. Below the lower limit of this range, the viscosity and concentration of the resulting endothermic liquid will become too high, resulting in reduced heat exchange efficiency and insufficient heat absorption rate, as described above. The heat absorber used in the present invention is carbon black or a mixture of carbon black and a metal oxide pigment. Examples of carbon black include furnace black, lamp black, thermal black,
Any conventionally known carbon black or activated carbon for use in rubbers, colorants, inks, etc., such as acetylene black and channel black, can be used.

Preferred metal oxide pigments that may be used in combination with these carbon blacks are oxides of iron, chromium, cobalt, nickel, copper, etc. Specifically, iron black, chrome black, Bengara black, chrome black, etc. Green, cobalt green, copper oxide, zinc-iron brown, titanium-cobalt nickel-zinc green, copper-chromium, black, copper-iron
Examples include manganese black. By using such metal oxide pigments together with carbon black,
Heat radiation due to radiation of the heat-absorbing liquid can be prevented, and heat collection efficiency can be improved. These metallized pigments are preferably used in a proportion of about 0.5 to 1 part by weight per part by weight of force-pump rack. The dispersing agent used in the present invention is an aromatic sulfonic acid formalin condensate or a salt thereof. For example, preferred ones include an 8-naphthalene sulfonic acid formalin condensate and its sodium salt, a phenolsulfonic acid formalin condensate and its sodium salt. Examples include salts, alkylnaphthalene sulfonic acid formalin condensates, and sodium salts.

By using these dispersants, it was possible to obtain an endothermic liquid that can withstand repeated use over a long period of time. The dispersion medium used in the present invention is selected from the group consisting of ethylene glycol, propylene glycol, glycerin, mixtures thereof and mixtures thereof with water.

When these media contain water, about 0 to
A water content of 85% by weight is preferred. It should contain water, especially if the medium is glycerin. The essential components of the heat-absorbing liquid of the present invention are as described above, but various other additives such as various water-dropping polymers, emulsifiers, stabilizers, preservatives, and anti-mirror agents may be added as necessary. be able to.

The endothermic liquid of the present invention can be easily produced by dispersing the above-mentioned components using a conventional dispersing machine such as a ball mill, homomixer, attritor, sand mill, colloid mill, roll, etc. It can be prepared.

The heat-absorbing liquid of the present invention thus obtained is a uniform black liquid and is useful as a heat-absorbing liquid for solar water heaters and heat collectors.

In other words, in such applications, the temperature is raised and lowered countless times over a long period of time, and the temperature is constantly exposed to sunlight (during the daytime). Good dispersion stability can be maintained for a long period of time under highly concentrated conditions. Furthermore, when conventional carbon black is used, the carbon black tends to precipitate and deposit on the inner surface of circulation equipment such as pipes of water heaters and heaters, significantly reducing heat absorption and heat exchange performance. In contrast, the endothermic liquid of the present invention hardly exhibits such a tendency. Such performance is believed to be due to the use of a specific dispersant and a specific dispersion medium. Furthermore, in the present invention, when a metal oxide pigment is used as a part of the heat absorbing body, although the reason is not necessarily clear, the heat radiation of the heat absorbing liquid during heat absorption is clearly suppressed, so that the heat absorption efficiency is improved. was significantly improved. Next, the present invention will be explained in more detail with reference to Examples.

Note that parts and percentages in the text are based on weight. Example 1 10 parts of carbon black (Mitsubishi Carbon #30), sodium salt of naphthalene sulfonic acid formalin condensate (
5 parts of Kao Atlas (Demol N) and 85 parts of water were mixed and treated with a dispersant using a ball mill to prepare a dispersion having a particle size of 1 French or less.

0.5 parts of the dispersion, 5 parts of ethylene glycol, 5 parts of Demol N, and 44.5 parts of water were uniformly mixed to obtain an endothermic liquid of the present invention having a freezing point of -37°C. The liquid was heated to 105℃
After continuous heat treatment for 100 hours, the dispersibility of carbon black was examined using a microscope, and it was found that the dispersibility of carbon black remained the same as before heating. Example 2 Activated carbon (Nimura Chemical Industry, Daebatsu K) 1 dollar part, Demol N5
1 part and 85 parts of water were blended and dispersed using a sand mill to prepare a dispersion having a particle size of 3# or less.

0.5 parts of the dispersion, 50 parts of propylene glycol, 5 parts of alkylnaphthalene sulfonic acid formalin condensate (Kao Atlas, Demo-ru MS) and 44.5 parts of water were uniformly mixed, and the freezing point was lowered to -3. 0 of the endothermic liquid of the present invention was obtained. The liquid was continuously heated at log C for 100 feeding hours in the same manner as in Example 1, and then diluted 25 times with water to confirm the dispersibility of activated carbon, and the transmittance was measured using a spectrophotometer. However, the transmittance curve matched that of the 29-tone diluted solution before heating, and the dispersion stability after heating was still good. Example 3 Dipyroxide Green #9430 (Dainichisei Chemical Industry Co., Ltd.,
30 parts of Co-AI-Cr based oxide pigment), 5 parts of sodium salt of phenol sulfonic acid, naphtholsulfonic acid formalin condensate (Kao Atlas, Demol SC30) and 65 parts of water were dispersed in a ball mill to form particles. A dispersion having a diameter of 5 mm or less was prepared.

The dispersion Meto, 0.5 parts of the carbon black dispersion prepared in Example 1, 50 parts of ethylene glycol, Demol S
5 parts of C30 and 43.5 parts of water were uniformly mixed together,
An endothermic liquid of the present invention was obtained. In order to evaluate the calculated thermal efficiency of the liquid, a heat collector was manufactured in accordance with the regulations of N-Spot (United States Department of Commerce Bureau of Standards), and the above liquid 7 was circulated.
When the heat collection efficiency was measured at each temperature level during the southerly phase, the heat loss was 5 to 15% lower than that of the liquid containing only carbon black in Example 1, and it was found that the heat loss was 5 to 15% lower, especially in the high temperature range of 70 to 90. %, indicating a high heat collection effect. Example 4 Dipyroxide #9510 (Dainichiseika Kagyo, Cu-C)
3 parts of (complex oxide pigment), 3 parts of sodium salt of naphthalene sulfonic acid formalin condensate (Kao Atlas, Mighty 150), 65 parts of Demol N group, and 65 parts of water were dispersed in a colloid mill to form particles. A dispersion having a diameter of 5 mm or less was prepared.

0.5 part of the nuclear dispersion, 5 parts of ethylene glycol, 5 parts of Demol N, and 44.5 parts of water were uniformly mixed to obtain an endothermic liquid of the present invention. When the heat collection efficiency of the liquid was measured in the same manner as in Example 3, it was found that the heat loss was 5 to 20% lower than that of the liquid of Example 1 containing only carbon black.
In the high temperature range of 0 to 9 pm, the amount of heat was reduced by 10 to 20%, and the heat collection efficiency was further improved. Example 5 Example 4
The same results as in Example 4 were obtained even when chromium oxide green or cupric oxide was used instead of the metal oxide pigment.

Claims (1)

[Claims] 1 In a liquid for solar heat absorption consisting of a dispersion medium, a dispersant, and a heat absorber, the dispersion medium is ethylene glycol,
It is selected from the group consisting of propylene glycol, glycerin, mixtures thereof, and mixtures of these with water, the dispersant is an aromatic sulfonic acid formalin condensate or a salt thereof, and the heat absorber is carbon black or carbon. A solar heat absorbing liquid characterized by being a mixture of black and a metal oxide pigment.