JPS6312504B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention uses trifluoroethanol (hereinafter referred to as
It is abbreviated as TFE. ) as a working fluid. A closed circulation system for working fluid is formed that circulates between a regeneration section that heats and evaporates the working fluid and a condensation section that cools and liquefies the working fluid.The latent heat of condensation of the working fluid is sent out from the condensation section to the outside of the system to reduce the load. For example, heat pipes and thermosiphons are known as representative heat transfer devices that supply heat to the
Furthermore, various substances such as water, ethanol, Freon, etc. are conventionally known as the working fluid. However, in conventional heat transfer devices that use water, ethanol, Freon, mercury, cesium, pentane, heptane, etc. as working fluids, depending on the type of working fluid, some devices have poor thermal stability under high-temperature conditions. They have various drawbacks, such as being highly corrosive to structural materials (mainly iron materials), being toxic to the human body and at risk of explosion, having a high freezing point and being unsuitable for use in cold climates, and being expensive. There is. In addition, heat supply methods to the regeneration section of this type of heat transfer equipment include electric heaters, steam, oil burners, gas burners, etc., but among these, the most efficient and simple and compact equipment. In this direct fire method, problems arise particularly in terms of thermal stability of the working fluid under high temperature conditions, corrosiveness to the structural materials of the device, and safety. In view of this, the present invention uses TFE or a mixed solution of TFE and water (TFE), which has a weak corrosive force against metals even in high-temperature regions and has excellent thermal stability, as a working fluid for this type of heat transfer device. The purpose of the present invention is to provide a heat transfer device that is compact and capable of stably and safely supplying heat to a load even under high-temperature conditions such as an open flame method. Table 1 shows an example of the physical properties of TFE and the physical properties of an aqueous TFE solution used as a working fluid in a heat transfer device.

[Table] Furthermore, the freezing point (melting point) and latent heat of vaporization of the TFE aqueous solution relative to the water weight % are shown in FIG. TFE does not have a combustion point (that is, if a flame is released from TFE, it will not continue burning), and even if an accident such as TFE leakage occurs, it can be easily removed by mixing with water etc. Furthermore, it is non-explosive at all vapor concentrations with air and satisfies non-toxicity standards regarding skin contact. like this
Due to the physical properties of TFE, it is preferable to use TFE as a working fluid when the heat transfer device is used in a home heater. Furthermore, TFE has a property that it has a low corrosive power against metals such as iron, copper, steel, and aluminum even under high temperature conditions, and a TFE aqueous solution has an even lower corrosive power than pure TFE. Furthermore, as is clear from Figure 1, the latent heat of vaporization of the TFE aqueous solution increases in proportion to the water content (for example, in the case of 15% water, it becomes 155 kcal/Kg,
Greater than pure TFE (83kcal/Kg). ), TFE aqueous solution has a larger amount of heat transfer per unit amount than pure TFE, and the freezing point of TFE aqueous solution is the lowest (-64℃) at 3.0% water by weight, making it difficult to use in cold climates. There is also less possibility of freezing of the working fluid. in this way
Although a TFE aqueous solution has one advantage over pure TFE as a working fluid, it has disadvantages as a working fluid, such as an increase in the freezing point if the water content increases too much. Therefore, the water content is less than 15% by weight.
Aqueous TFE solutions and TFE are suitable as working fluids for this type of heat transfer device. Furthermore, since TFE and TFE aqueous solution are liquids at room temperature, they can be easily filled into the working fluid circulation system of the heat transfer device. Focusing on the known physical properties of TFE and TFE aqueous solution as well as experimental measurement data as described above, an experiment was conducted by filling the thermosiphon shown in Figure 2 with TFE aqueous solution and TFE containing 15% by weight or less of water. However, the working fluid formed a stable closed circulation cycle, and the heat transfer was improved by 5 to 6% compared to the conventional one. In FIG. 2, 1 is a regeneration section, 2 is a sight glass section for observing the flow state of the working fluid, 3 is a condensation section, and 4 is a storage section, which are connected to pipes 5, 6,
7 and 8 to form a working fluid circulation system 9, and transfer the condensation latent heat and sensible heat energy of the working fluid to a load side (not shown) outside the system 9 through a radiator 10 surrounding the condensing section 3. The thermosiphon is configured to send cooling water to (1). Thus, the working fluid heated in the regeneration section 1 evaporates, forming a liquid phase part 11 on the inner wall of the pipe 5 and a gas phase part 12 in the hollow part of the pipe 5, in a gas-liquid two-phase flow state. It ascends inside the sight glass section 2 and piping 6 and reaches the condensing section 3. The working fluid that has reached the condensing section 3 is condensed and cooled by the cooling water flowing through the radiator 10 and then transferred to the piping 7.
The working fluid flows down through the storage section 4 and piping 8, returns to the regeneration section 1, and circulates through the system 9. In this way, the thermal energy of the working fluid is continuously supplied from the condensing section 3 to the load side via the heat radiating section 10. As described above, the present invention forms a closed circulation system for the working fluid that circulates between the regeneration section and the condensation section, and sends the thermal energy given to the working fluid in the regeneration section from the condensation section to the outside of the system. In heat transfer equipment, the working fluid contains water within a range of 15% by weight or less.
Since it uses a TFE aqueous solution and TFE,
Even if the heat source supply method for the regeneration section is a direct fire method, the stability of the working fluid is maintained, the equipment is safe with little corrosion, and the entire equipment can be made compact. Furthermore, since TFE or TFE aqueous solution is neither toxic nor explosive to the human body, the device of the present invention can also be used in home heating and hot water systems.
It is useful for practical use, as it is suitable for use in cold regions.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the weight percent of water in a TFE aqueous solution, its freezing point, and the latent heat of vaporization under one atmospheric pressure, and Figure 2 is a system diagram of a thermosiphon, which is an embodiment of the device of the present invention. 3 are views showing the flow state of the working fluid from the regeneration section to the condensation section in an embodiment of the present invention. 1... Regeneration section, 3... Condensation section, 9... Circulation system.

Claims (1)

[Claims] 1. A closed circulation system for working fluid is formed in which the working fluid is circulated through a regeneration section that heats and evaporates the working fluid and a condensation section that cools and liquefies the working fluid. 1. A heat transfer device configured to send out thermal energy from a condensing section to the outside of a closed circulation system, characterized in that the working fluid is made of trifluoroethanol. 2. A heat transfer device according to claim 1, wherein the working fluid is an aqueous trifluoroethanol solution containing up to 15% by weight of water.