JP4307091B2 - Heat transfer medium and heat transfer system using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat transfer medium that uses a surfactant aqueous solution as a heat transfer medium to reduce fluid friction, and a heat transfer system using the heat transfer medium.
[0002]
[Prior art]
For example, in a district cooling and heating system, heat from a heat receiving (heat supply) side plant is supplied to a heat radiating (heat utilization) side plant, for example, an air conditioning system such as a building. Is used. The piping for circulating the cooling / heating medium has a length of several kilometers or more, and the power for transporting water as the cooling / heating medium is considerably large, which is about 60 to 70% of the running cost of the district cooling / heating system. It is said.
[0003]
For this reason, as an effective method for reducing the power for transporting water, a method has been proposed in which a surfactant aqueous solution exhibiting viscoelasticity is used as a heat transport medium and the flow frictional resistance of the heat transport medium is significantly reduced. (For example, see Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4). When several tens to several thousand ppm of a surfactant made of a mixture of a specific quaternary ammonium salt and salicylate is dissolved in water flowing through a pipe connecting the heat receiving side plant and the heat radiating side plant, the surfactant is dissolved in water. Thus, it is said that the micelle is formed by arranging the hydrophilic base portion around the hydrophobic base portion in the outer peripheral portion, and the micelle forms a rod-like form and is entangled in the higher order to show viscoelasticity.
[0004]
[Patent Document 1]
Japanese Patent Publication No. 3-76360 [Patent Document 2]
Japanese Patent Publication No. 4-6231 [Patent Document 3]
Japanese Patent Publication No. 5-47534 [Patent Document 4]
JP-A-8-311431
[Problems to be solved by the invention]
The fact that the friction reducing effect can be obtained by using such a surfactant is limited to the use in the closed system circulation pipe (circulation line) in the heat receiving side plant and the heat radiation side plant. There is no effect. This is because, when a heat transfer medium containing such a surfactant is used in an open circulation pipe represented by a cooling tower, the foam is vigorously foamed in the cooling tower due to the surface active effect of the surfactant. There is a problem that the heat transfer medium (that is, the circulating liquid) is reduced due to scattering by the wind. If the heat transfer medium is reduced in this way, circulation of the heat transfer medium in the system is delayed and a fatal problem of system down occurs. In addition, when foaming occurs in the cooling tower, there is a problem that the generated bubbles are scattered by the wind and contaminate the surrounding area.
[0006]
An object of the present invention is to provide a heat transfer medium with less foaming even when an aqueous solution of a surfactant is used as a heat transfer medium in an open circulation pipe.
Another object of the present invention is to provide a heat transfer system that can suppress a decrease in heat transfer medium during operation and can be stably operated over a long period of time.
[0007]
[Means for Solving the Problems]
When the present inventors use an aqueous surfactant solution having a friction reducing effect as a heat transfer medium, when an antifoaming agent is added to the aqueous solution, the surfactant in the aqueous solution is almost foamed even in an open circulation pipe. It was found that the effect of reducing friction can be sustained and the object can be achieved.
[0008]
The heat transfer medium according to claim 1 of the present invention is a heat transfer medium circulated through a heat receiving side system, a heat radiating side system, a forward line and a return line connecting them, and an antifreezing agent, an antifoaming agent, and A surfactant for reducing frictional resistance in piping is added to an aqueous liquid, the antifoaming agent is a silicone compound compound, and the concentration of the antifoaming agent is 8 to 300 ppm .
[0009]
According to the present invention, when using a heat transport medium in which a surfactant having a friction reducing effect is added to an aqueous liquid containing an antifreeze that can be used without freezing even under low temperature conditions, an aqueous surfactant solution is used. When a strong stimulus is applied to the gas-liquid interface, foaming occurs, but foaming can be suppressed by adding an antifoaming agent to the heat transfer medium. This is because the antifoaming agent adheres to the foam film and enters the foam film, and then expands the foam film to break the foam film (known as the so-called Ross theory). Thereby, foaming of the surfactant in the aqueous solution (in the liquid phase) is suppressed, and the friction reducing effect can be prevented from being reduced. Since the foaming phenomenon of the surfactant aqueous solution occurs in the open circulation pipe, a sufficient effect can be obtained particularly by using this heat transfer medium in the open circulation pipe.
Moreover, since the antifoaming agent is a silicone compound compound, foaming can be suppressed while maintaining the friction reducing effect of the heat transfer medium. Furthermore, since the concentration of the antifoaming agent is 8 to 300 ppm, generation of bubbles in the heat transfer medium can be sufficiently suppressed.
[0010]
In the heat transfer medium according to claim 2 of the present invention, the antifoaming agent is at least one compound selected from dimethyl silicone oil and polyoxyalkylene silicone oil .
[0011]
According to the present invention, since the antifoaming agent is at least one compound selected from dimethyl silicone oil and polyoxyalkylene silicone oil, foaming is effectively performed while maintaining the friction reducing effect of the heat transfer medium. Can be suppressed.
[0013]
A heat transfer system according to claim 3 of the present invention is characterized by using the heat transfer medium according to claim 1 or 2 .
According to the present invention, since the above-described heat transfer medium is used, even when the heat transfer medium is used in an open system circulation pipe, the heat transfer medium hardly generates bubbles, and a desired friction reducing effect is maintained for a long time.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a heat transfer medium and a heat transfer system using the same according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an example of a heat transfer system using a heat transfer medium according to the present invention.
[0015]
In FIG. 1, the illustrated heat transfer system includes a heat receiving side system 2 that applies heat (cold heat and / or heat) to a heat transfer medium, and a heat dissipation side system 4 that dissipates the heat of the heat transfer medium. The heat receiving side system 2 is, for example, a chiller / heater, a heat exchanger for cooling a power generation engine, a waste heat recovery machine for a garbage incinerator, and the heat radiating side system 4 is, for example, a cooling tower.
[0016]
The heat receiving side system 2 and the heat radiating side system 4 are connected via a forward line 6 and a return line 8, and the forward line 6 and the return line 8 circulate through a heat transfer medium described later through the heat receiving side system 2 and the heat radiating side system 4. Establish a circulation pipe to be used.
[0017]
In this heat transfer system, a circulation pump 10 is disposed in the forward line 6, and a flow meter 12 is disposed in the return line 8. The circulation pump 10 circulates the heat transfer medium through a circulation pipe, and the heat transfer medium that has received heat in the heat receiving side system 2 is supplied to the heat radiating side system 4 through the forward line 6 and is radiated by the heat radiating side system 4. The heat transfer medium after heat radiation returns to the heat receiving side system 2 through the return line 8, and the heat transfer medium is circulated in this way. The flow meter 12 is composed of, for example, an electromagnetic flow meter, and measures the flow rate of the heat transfer medium flowing through the return line 8.
[0018]
The heat transfer medium is applied to such a heat transfer system, and is used by filling the circulation pipe. In this heat transfer system, the heat radiation side system 4, for example, the cooling tower, is an open system device, and can be advantageously applied to a system including such an open system circulation line (circulation piping).
[0019]
In this heat transfer medium, a surfactant and an antifreeze are added to water, which is a heat (cold / heat) medium, and an antifoaming agent is added to suppress a foaming phenomenon that is particularly problematic in an open system circulation line. Yes.
[0020]
The type of surfactant contained in the heat transfer medium is not particularly limited. For example, a mixture of cetyltrimethylammonium salt and salicylate, a mixture of stearyltrimethylammonium salt and salicylate, dodecyltrimethylammonium salt and salicylic acid. A mixture of salts, a mixture of hexyltrimethylammonium salt and salicylate, a mixture of heptyltrimethylammonium salt and salicylate, a mixture of oleylbis (hydroxyethyl) methylammonium salt and salicylate, a mixture of oleylhydroxyethyldimethylammonium salt and salicylate, Mixture of oleyl tri (hydroxyethyl) ammonium salt and salicylate, oleylhydroxyethyldimethylamine oxide, oleylbis (hydroxyethyl) methyl Nmo bromide oxide, Oreirutori (hydroxyethyl) ammonium oxide, and the like Cecil trimethylammonium oxide. If the concentration of this surfactant is small, the friction reducing effect does not appear, and if it is too large, the friction reducing effect does not increase beyond a certain value, which is economically wasteful. For this reason, the concentration is preferably 300 to 4000 ppm, more preferably 500 to 2500 ppm.
[0021]
The type of antifoaming agent added to the heat transfer medium is not particularly limited, but is preferably a silicone compound compound, for example, at least one selected from dimethyl silicone oil and polyoxyalkylene silicone oil. Are preferred. Regarding the concentration of the antifoaming agent, if it is small, the defoaming effect is small, and if it is too large, the defoaming effect is not particularly changed, but the friction reducing effect of the surfactant is inhibited. For this reason, the concentration is preferably 5 to 1000 ppm, more preferably 8 to 500 ppm, and even more preferably 8 to 300 ppm.
[0022]
In addition, there is no particular limitation on the type of antifreeze contained in the heat transfer medium, preferably at least one compound selected from glycols such as ethylene glycol and propylene glycol, and alcohols such as methanol, ethanol, and propanol, Propylene glycol is particularly preferred. Regarding the concentration of antifreeze, a low concentration increases the solidification temperature of the heat transfer medium, which is not preferable because the temperature range that can be used at low temperatures is reduced. On the contrary, if the concentration is high, the operating temperature range is lower. However, it is not preferable because the viscosity becomes large and the flow becomes difficult. For these reasons, the concentration of the antifreeze is preferably 5 to 40% by weight, more preferably 7 to 30% by weight.
[0023]
The embodiments of the heat transfer medium and the heat transfer system using the heat transfer medium according to the present invention have been described above. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the present invention. Or it can be modified.
[0024]
【Example】
Next, in order to confirm the effect of the heat transfer medium described above, the following test was performed.
As an example <br/> embodiment, water as the heat medium, 30% by weight of propylene glycol as antifreeze, 1000 ppm surfactant stearyl trimethyl ammonium chloride and sodium salicylate as (friction reducing agent), respectively, 600 ppm was added, and a silicone compound antifoaming agent (manufactured by Shin-Etsu Chemical Co., Ltd., silicone antifoaming agent KS-66) was added as an antifoaming agent. (Also referred to as “friction resistance reducing aqueous solution”).
[0025]
Comparative Example 1
As Comparative Example 1, an aqueous solution of the same components was prepared except that no antifoaming agent was added to the heat transfer medium of the above example.
Comparative Example 2
As Comparative Example 2, all the same components except that a metal soap type antifoaming agent (manufactured by San Nopco Co., Ltd., Nopco NXZ) was used as the antifoaming agent in place of the silicone compound type antifoaming agent in the heat transfer medium of the above example. Then, aqueous solutions in which metal soap type antifoaming agents were dissolved at various concentrations were prepared.
[0026]
(1) Evaluation test of friction reduction effect Carbon steel pipe (SGP black pipe) 30m with a pipe size of 50A, a single spiral pump (manufactured by Sanwa Hydrotech Co., Ltd., model MPL-8515), and an electromagnetic flow meter (Co., Ltd.) A loop line was constructed using Hitachi, Ltd., model FMR104W-40). The power of the single spiral pump was 7.5 kW at the rating (60 kHz), and the pump power was adjusted by performing inverter control on this single spiral pump. The pump power was controlled by an inverter, and the pump power reduction rate was measured and evaluated so that the flow rate through the pipe would be constant at the rated flow rate value of the pump (250 dm ³ / min). In general, since pump power is proportional to the cube of the inverter frequency, the pump power reduction rate is obtained by {1- (inverter frequency / 60) ³ } × 100.
[0027]
For the heat transfer media of Examples, Comparative Example 1 and Comparative Example 2, the above-described evaluation test of the friction reduction effect was performed. In this evaluation test, the temperature of these heat transfer media was 30 ° C.
[0028]
The result of the evaluation test of the friction reducing effect is as shown in FIG. In the examples, the pump power reduction effect was almost constant and a reduction effect of about 30% was obtained in the range where the concentration of the antifoaming agent was up to 100 ppm, but the pump power reduction effect was gradually increased in the range where the concentration exceeded 100 ppm. Decreased. On the other hand, in Comparative Example 1, the pump power reduction effect was about 30%. In Comparative Example 2, a pump power reduction rate of about 30% was obtained when the concentration of the antifoaming agent was 1 ppm. However, when the concentration exceeded 1 ppm, the pump power reduction effect was drastically reduced, The effect was not obtained.
[0029]
(2) Evaluation test of foamability The evaluation test of foamability was performed according to JIS K 3362-1998 "Synthetic detergent test method". For the heat transfer medium of Example, Comparative Example 1 and Comparative Example 2, the height of bubbles generated when 200 ml of a heat transfer medium having a temperature of 25 ° C. was dropped from 900 mm onto the liquid surface in 30 seconds was visually measured. It was evaluated by doing.
[0030]
The results of the foamability evaluation test were as shown in FIG. In the examples, the foaming phenomenon was observed when the concentration of the antifoaming agent was less than 1 ppm. However, when the concentration of the antifoaming agent exceeded 1 ppm, the degree of foaming increased as the concentration of the antifoaming agent increased. It gradually decreased, and in the concentration range of 10 ppm or more, the occurrence of the foaming phenomenon was below the observation limit. In Comparative Example 2, the same foaming reduction effect as that of the example was obtained. In contrast, in Comparative Example 1, a large foaming phenomenon was observed.
[0031]
From the evaluation test of the friction reduction effect and the evaluation test of foamability described above, the following has been found. In the Example using a silicone compound type antifoamer, it turned out that a foaming phenomenon can be suppressed, maintaining a pump power reduction effect. Also, these evaluation tests have found that there are preferable conditions for the concentration of the antifoaming agent to be added. On the other hand, in Comparative Example 2 using the metal soap antifoaming agent, the foaming property shows almost the same tendency as the result of the example, but for the pump power reduction effect, when the concentration of the antifoaming agent is higher than 1 ppm, It was observed that the effect rapidly decreased, and it was found that the foamability could not be suppressed while maintaining the pump power reduction effect as in the example.
[0032]
According to the heat carrier medium of claim 1 of the present invention, because the defoaming agent to the heat transport medium is added, it is possible to suppress significantly the occurrence of the foaming phenomenon, keeping the friction reducing effect for a long time Can do. In addition, since the antifoaming agent uses a silicone compound compound, foaming can be suppressed while maintaining the friction reducing effect of the heat transfer medium. Furthermore, since the concentration of the antifoaming agent is 8 to 300 ppm, generation of bubbles in the heat transfer medium can be sufficiently suppressed.
[0033]
Moreover, according to the heat carrier medium of claim 2 of the present invention, since the antifoaming agent is at least one compound selected from dimethyl silicone oil and polyoxyalkylene silicone oil, Foaming can be effectively suppressed while maintaining the friction reducing effect.
[0034]
According to the heat transfer system of the third aspect of the present invention, even when the heat transfer system is used in an open system circulation pipe, the heat transfer medium hardly generates bubbles, and a desired friction reducing effect is maintained for a long time.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an example of a heat transfer system to which a heat transfer medium according to the present invention is applied.
FIG. 2 is a diagram showing the relationship between the concentration of an antifoaming agent added to a heat transfer medium and a pump power reduction rate.
FIG. 3 is a diagram showing the relationship between the concentration of an antifoaming agent added to a heat transfer medium and the degree of foaming.
[Explanation of symbols]
2 Heat receiving side system 4 Heat radiation side system 6 Outward line 8 Return line 10 Circulation pump

Claims (3)

A heat receiving medium, a heat radiating side system, a heat transfer medium circulated through a forward line and a return line connecting them, and an antifreezing agent, an antifoaming agent, and a surfactant for reducing frictional resistance in piping , A heat transfer medium added to an aqueous liquid , wherein the antifoaming agent is a silicone compound compound, and the concentration of the antifoaming agent is 8 to 300 ppm. 2. The heat carrier medium according to claim 1, wherein the antifoaming agent is at least one compound selected from dimethyl silicone oil and polyoxyalkylene silicone oil . A heat transfer system using the heat transfer medium according to claim 1 .

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