JPH0415489A - Working medium for heat pipe - Google Patents

Abstract

PURPOSE:To reduce a heat loss and provide a fast transferring of high amount of heating calorie by a method wherein working medium to be applied in a heat pipe is a magnetic fluid dispersed into mixed solvent containing mineral oil system and/or synthetic oil system solvent and solvent of low boiling point having ferromagnetic fine particles. CONSTITUTION:Magnetic fluid 11 is enclosed in a closed circuit 31 for a heat pipe to which a magnet 2 is adjacent. A solar heat heating device receives a solar heat R at a heat absorbing panel 4 acting as a heat receiving part so as to supply a heating calorie to the fluid 11 in the closed circuit. Solvent of low boiling point in the fluid 11 evaporates in the heat pipe, condenses at a heat radiation part 5 and is liquified so as to discharge an evaporation latent heat. This heating calorie can be recovered and utilized as hot air. In this case, the working medium has a low heat loss by using the magnetic fluid containing solvent of low boiling point with a high evaporating latent heat, and can transfer a large amount of heat, so that it is possible to increase a moving amount of heating calorie per unit time.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides an excellent energy conversion system, particularly a heat exchange system. The present invention relates to a heat exchange method using a heat pipe, which uses a magnetic fluid containing a point solvent.

<Prior art> Magnetic fluid is made up of very fine ferromagnetic particles with a particle size of approximately 10r+m that are stably dispersed in an organic solvent or water, and cannot be used in a gravitational field, a normal centrifugal field, or a magnetic field. Also, particles do not coagulate or settle, and the liquid itself behaves as if it were ferromagnetic.

” - As a method for producing the magnetic fluid described above, for example, a basic salt of an unsaturated fatty acid such as oleic acid is added to an ice suspension of a wet-synthesized ferromagnetic metal oxide such as manetite, and the ferromagnetic metal oxide is A method of making an oil-based magnetic fluid by adsorbing and aggregating unsaturated fatty acid ions on fine particles of substances and dispersing the agglomerates in oil (Japanese Patent Publication No. 53-17
No. 118), the aggregate obtained in the same manner was placed in water,
A method is known in which a water-based magnetic fluid is prepared by adding an anionic or nonionic surfactant having 9 or more carbon atoms in the hydrocarbon chain (Japanese Patent Publication No. 40069/1983).

The above-mentioned method for manufacturing magnetic fluid is provided as a highly complete method, and the obtained magnetic fluid has already been used for seals on rotating shafts, specific gravity selection, various tambours, acceleration sensors, tilt sensors, etc. The field of application has been expanded.

On the other hand, magnetic fluid, which is a dispersion of fine ferromagnetic fluid particles, has
Below the specific Curie temperature, magnetization tends to decrease as the temperature rises. Taking advantage of this property,
A system for converting thermal energy into kinetic energy has been proposed. This is a system in which, for example, when a magnetic field is applied to a closed flow path with a temperature difference, the magnetic fluid within the flow path spontaneously circulates due to the nonequilibrium force. In Figure 1, which shows the principle of this energy conversion system, when we start from a part A with a cold magnetic fluid, the magnetic fluid at A is attracted by the magnetic field of the magnet, and the pressure increases according to the magnetic fluid Bernoulli equation. . When the ferrofluid or part B, which is within the magnetic field, is then heated, the magnetization of the ferrofluid at B decreases and the pressure becomes less than that at A. Due to the difference in pressure within this magnetic field, the fluid does not move in the direction of the arrow.

In this energy conversion system, it has been clarified that the force that drives the magnetic fluid is proportional to the rate of change in magnetization of the magnetic fluid at two points A and B, where there is a temperature difference.
Such a system is generally used near room temperature due to the heat resistance of the magnetic fluid itself, so it is necessary that the temperature dependence of the magnetization of the magnetic fluid near room temperature is large.

A magnetic fluid containing manetite as a magnetic powder obtained by the above-mentioned manufacturing method cannot be used for this energy conversion system because the temperature dependence of magnetization is too low.

Therefore, as a ferrite with a large rate of change in magnetization that can be used in such an energy conversion system, manganese-zinc (Mn-Zn) based ferrite proposed in JP-A-1-165104 has been proposed as a magnetic powder. There are magnetic fluids that do this.

<Invention or Problem to be Solved> However, the conventional magnetic fluids that have a Curie point of 400°C or higher or Mn-Zn ferrite as magnetic powder have a temperature dependence of magnetization. For example, Fig. 2 shows a curve (
Fig. 3 shows the thermomagnetic curve measured by separating only the powder from the magnetic fluid into Macnetite 1, and as is clear from these, it is clear that the temperature of the manetite powder at 0°C and 100° The magnetization change rate Δσ in a magnetic field of 4×105A#n in C is only 0.03T.

Furthermore, the temperature dependence of the magnetization of the kerosene hese magnetic fluid dispersed in the Macnetai 1 described in "-" is 3.2X 10
Apply a magnetic field of 5Δ/■ in the range of 0 to 100°C,
It is only 3 x 10'T10C.

Furthermore, when Mn-Zn ferrite is made into fine particles with a particle size of about 10 nm and the fine particles are used as magnetic powder to produce a magnetic fluid, the same conditions as above (3.2 x 105 A/m
The temperature dependence of magnetization in a magnetic field of 0 to 100° C. was only about 1 x ]0-'T/'C.

Therefore, since conventional magnetic fluids cannot be used in energy conversion systems such as those described above, magnetic fluids that have an extremely large temperature dependence of magnetization near room temperature and a large absolute value of magnetization, so-called temperature-sensitive fluids, are used. Although there is a strong demand for magnetic fluid, no high-performance temperature-sensitive magnetic fluid has been found so far.

<Means for Solving the Problems> The present invention has been proposed in view of the above, and the working medium used in the heat receiving section, the heat dissipating section, and the heat pipe in which the magnets are disposed contains ferromagnetic fine particles in a mineral oil-based solvent and/or The present invention relates to a working medium for a heat pipe, characterized in that it is a magnetic fluid dispersed in a mixed solvent consisting of a synthetic oil-based solvent and a low boiling point solvent.

As mentioned above, the present invention is characterized in that in a magnetic fluid used as a working medium of a heat pipe, a dispersion solvent is a solvent with a high latent heat of vaporization and low sensitivity.

As the ferromagnetic fine particles used in the present invention described above, any ferromagnetic fine particles obtained by a wet method, a dry method, or other methods can be used.

Further, the dispersion solvent used in the present invention is a mixed solvent consisting of a mineral oil solvent and/or a synthetic oil solvent and a low boiling point solvent, and the mineral oil solvent and the synthetic oil solvent are ordinary oil-based solvents. The dispersion solvent used in the magnetic fluid is any solvent that can stably disperse highly magnetic fine particles.

”-The low boiling point solvent used in the present invention is vaporized '1I
PPi is a solvent with high heat and low temperature, which is selected depending on the temperature conditions of the pipes used. For example, low boiling point solvents with a boiling point below room temperature include n-butane, fluorodichloromethane, fluorotrichloromethane, ethyl chloride, methyl bromide, and tetramethyl silicone. Examples of low boiling point solvents include normal pentane, 2-pentene, inhexane, normal hexane, methylene chloride, ethylidene chloride, vinylidene chloride, 1,2-dichloroethylene, isopropyl chloride, allyl chloride, chloroform, ethyl bromide, ~lichlorofluoroethane, etc., and low boiling point solvents from the Buddha point of 709C to about 100'C include n-pentane, cyclohexane, methylcyclohexane, benzene, carbon tetrachloride, ethylene chloride, 1,1.1- Examples include trichloroethane, trichloroethylene, 1,2-dichloropropane, methyl chloride, and hexamethyldisiloxane.

Among the above-mentioned low boiling point solvents, particularly effective solvents include ethyl chloride and methyl bromide for those with a boiling point below room temperature, and 2-pentene and ethyl bromide for those with a boiling point of between room temperature and 70'C. Examples of those with a temperature of 7°C to 100°C include benzene and hexamethyldisiloxane.

Each of the above-mentioned low-boiling point solvents is sufficiently different from mineral oil-based solvents and synthetic oil-based solvents used as dispersion solvents for ordinary magnetic fluids, such as kerosene, icosylnaphthalene, and poly-α-olefin, in any proportion. They have the property of dissolving each other, and furthermore, the surface-treated highly magnetic fine particles can be stably dispersed even with the low boiling point solvent alone.

The effect of the low boiling point solvent in the present invention will be explained with reference to FIG. The evaporated low boiling point solvent radiates heat in the heat radiating section C, condenses, and returns to the dispersion solvent of the magnetic fluid. In other words, the amount of heat received in the heat receiving section B is transferred to the heat dissipating section C as latent heat of vaporization through the low boiling point solvent, and the vaporized low boiling point solvent condenses and releases the latent heat, so the amount of heat is transferred efficiently. It can then be collected and used.

Therefore, the low boiling point solvent used in the present invention has a low vapor pressure, a high latent heat of vaporization, and has a high stability of magnetic fluid (dispersion of ferromagnetic particles) during evaporation, condensation, or repeated evaporation and condensation. (Stability) is required.

Incidentally, the proportion of the dispersion solvent in the magnetic fluid is generally 40 to 7.
However, the proportion of the low boiling point solvent contained in the dispersion solvent of the magnetic fluid in the present invention is preferably 30 to 50%. If the proportion of the low boiling point solvent is less than 30%, the amount of heat transferred decreases, and if it exceeds 50%, the stability of the magnetic fluid may be impaired during repeated evaporation and condensation.

- A heat exchange system configured by using a magnetic fluid as described above as the working medium of the P1 pipe and arranging a heat receiving part, a heat radiating part, and a magnet so as to face the heat pipe,
It can be used in a wide variety of fields and applications. For example, heat exchange systems that use low boiling point solvents with a boiling point below room temperature are used to melt snow on road surfaces, tunnel drainage pipes, etc. In addition, examples of the use of heat exchange systems that use low boiling point solvents with boiling points ranging from room temperature to about 70'C include heat receiving panels for air conditioning and heating, rotating bodies such as motors, etc. cooling, and furthermore, 70 to 100
Examples of uses of heat exchange systems using low boiling point solvents having a boiling point of .degree. C. include recovery of waste heat from boilers, air heaters for industrial furnaces, and the like.

- As mentioned above, the working fluid of the present invention uses a low boiling point solvent selected from a temperature range suitable for the intended use, and the magnetic fluid containing the low boiling point solvent is used in a heat pipe. By using it as a working fluid, heat loss can be reduced and heat can be transferred efficiently.

<Example> Example 1 Magnetic fluid with the following composition 1. was prepared and sealed in a closed circuit 3° of a heat vibrator facing the magnet 2 as shown in FIG.

The illustrated solar heater receives solar thermal energy R through a heat absorption panel 4 which is a heat receiving section, and receives magnetic fluid 1 in a closed circuit 32.
．． supplies heat to.

A magnetic fluid 1 supplied with heat, a low boiling point solvent 2
- Pentene evaporates in the heat pipe, condenses and liquefies in the heat radiator 5, which is formed by providing fins or the like to increase the surface area, and releases latent heat of vaporization. The released heat can be recovered and used as hot air by the fan 6.

(Composition of magnetic fluid 11) Ferromagnetic particles: Mn-Zn ferrite surface-treated with oleic acid having a particle size of 50 to 200 obtained by wet method 40 wt% solvent (1)
: Icosylnaphthalene 40 wt% solvent (2)
[Low boiling point solvent 1: 2-pentene 20 wt%] The method for manufacturing the two-part magnetic fluid 11 is to prepare an icosylnaphthalene-based magnetic fluid according to a general manufacturing method for magnetic fluid, and then add the above-mentioned method to the manufacturing method. It is prepared by adding 2-pentene in the same proportions and mixing uniformly with a homogenizer.

The room heating efficiency of the illustrated solar heater was 1.8 times higher than that using conventional magnetic fluid.

Example 2 A magnetic fluid 12 having the following composition was prepared and sealed in a closed circuit 32 from the pipe 1 to the pipe facing the magnet 2 as shown in FIG. The heat pipe of the illustrated snow melting system is buried vertically in the ground, with the second part of the pipe to heat 1 close to the ground surface 7, and the lower part located deep underground. The closed circuit 32 is received at the lower part of the closed circuit 32 which is a heat receiving part.
Heat is supplied to the magnetic fluid 1□ inside. Fluorodichloromethane, a low boiling point solvent in the magnetic fluid 12 supplied with heat, evaporates in the pipe to the heater 1, condenses and liquefies in a part of the closed circuit 3, which is the heat dissipation part, and releases latent heat of vaporization. do. The released heat is transferred to the ground surface 7 and melts the snow.

(Composition of magnetic fluid 12) Ferromagnetic particles: Mn-Zn ferrite surface-treated with oleic acid having a particle size of 50 to 200 particles obtained by wet method 45 wt% solvent (1)
: Kerosene 40 wt% solvent (2) [
Low Buddha point dissolution temperature J]: Fluorodichloromethane 1
5 wt% The method for manufacturing the magnetic fluid 12 containing two parts of -J is to prepare a kerosene-based magnetic fluid according to the manufacturing method of general magnetic fluids, and then add fluorodichloromethane to the above ratio. It is produced by uniformly mixing in an autoclave.

The snow melting efficiency on the ground surface shown in the figure was 1.5 times higher than when using conventional magnetic fluid.

Example 3 A magnetic fluid 13 having the following composition was prepared and sealed in a closed circuit 33 of a heat pipe facing a magnet 2 as shown in FIG.

The illustrated exhaust heat recovery type heater receives exhaust heat in a heat receiving section 8 provided with an exhaust gas flow path, and supplies the amount of heat to the magnetic fluid 13 in the closed circuit 33. Hexamethyldisiloxane, which is a low boiling point solvent in the magnetic fluid 13 supplied with heat, evaporates in the heat pipe, condenses and liquefies in the radiator 5 formed by increasing the surface area by providing fins, etc. Releases latent heat of vaporization. The released heat can be recovered and used as hot air by the fan 6.

(Composition of magnetic fluid 13) Ferromagnetic particles: Mn-Zn ferrite surface-treated with oleic acid having a particle size of 50 to 200 particles obtained by wet method 40 wt% solvent (1
): α-olefin 45 wt% solvent (2)
[Low boiling point solvent 1: Hexamethyldisiloxane 1
5 wt% Furthermore, in the manufacturing method of the magnetic fluid 13 described above, an α-olefin-based magnetic fluid is prepared according to the manufacturing method of a general magnetic fluid, and then hexamethyl is added to the magnetic fluid at the proportions shown in the figure. It is made by adding disiloxane and mixing it uniformly using a homogenizer.

The heat exchange efficiency of the heat capture and recovery heater shown in the figure was twice that of a conventional magnetic fluid.

<Effects of the Invention> As explained below, the working fluid of the present invention is capable of operating a conventional magnetic fluid by using a magnetic fluid containing a low boiling point solvent with a high latent heat of vaporization as the working fluid of a heat pipe. Less heat loss than when used as a medium
By quickly transferring a large amount of heat, it is possible to increase the amount of heat transferred per unit time.

Furthermore, the working medium of the present invention can be applied to a wide variety of fields and uses, since it is possible to create a heat exchange system by selecting a low boiling point solvent to be used based on the temperature range suitable for the application. It is something.

Furthermore, the present invention does not require special equipment;
Since it has a simple configuration, it is extremely easy to design and install.

Therefore, the present invention provides an extremely practical energy conversion system, and can be expected to have various applications and developments.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; Fig. 1 is a conceptual diagram showing the principle of an energy conversion system using a magnetic fluid, and Fig. 2 is a thermomagnetic curve of a kerosene-based magnetic fluid in which magnetite is dispersed. , Fig. 3 is a thermomagnetic curve of manetite powder, Fig. 4 is a schematic explanatory diagram of a solar heater using the present invention, Fig. 5 is a schematic explanatory diagram of a snow melting system using the present invention, and Fig. 6 is a schematic explanatory diagram of a solar heater using the present invention. FIG. 1 is a schematic explanatory diagram of an exhaust heat recovery type heater using the invention. Warm! (0c)

Claims (1)

[Claims] The working medium used in the heat receiving section, the heat dissipating section, and the heat pipe in which the magnets are arranged is a magnetic fluid made by dispersing ferromagnetic fine particles in a mixed solvent consisting of a mineral oil-based solvent and/or a synthetic oil-based solvent and a low boiling point solvent. A working medium for a heat pipe, characterized in that: