JPS6312505B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to n-perfluorooctane (hereinafter referred to as
It is abbreviated as nPFO. ) 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, conventional heat transfer devices using water, ethanol, freon, mercury, sodium, cesium, pentane, heptane, etc. as working fluids have poor thermal stability under high temperature conditions depending on the type of working fluid. , equipment structural materials (mainly iron,
Items that are highly corrosive to metal materials such as copper, aluminum, etc., items that are toxic to the human body or have a risk of explosion, items that have a high freezing point and are unsuitable for use in cold climates, or items that are expensive. There are drawbacks. 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. The direct fire method is generally adopted to obtain
In this direct fire method, there are particular problems with the thermal stability of the working fluid under high-temperature conditions, the corrosiveness of the structural materials of the device, and safety. In view of these points, the present invention employs nPFO, which has excellent physical properties such as relatively good thermal stability even in high temperature ranges and low corrosive force against metals, as the working fluid for this type of heat transfer device. The present invention also provides a heat transfer device that can stably and safely supply heat to a load even under high-temperature conditions such as in an open flame system. Table 1 shows the physical properties of nPFO used as the working fluid of the heat transfer device.

[Table] nPFO is a non-flammable substance and is a working fluid that poses little risk of causing a fire even if the working fluid of an open-fire heat transfer device leaks outside the system. In addition, nPFO has a freezing point of -35°C, so it is less likely to cause freezing of the working fluid even in cold climate regions, and since it is a liquid at room temperature, it is easy to fill the working fluid circulation system of a heat transfer device. Next, Table 2 shows the maximum operating temperature at which nPFO can be operated as a working fluid in the coexistence of copper, iron, and oil for a long time, obtained from a comparative experiment with fluorinated hydrocarbon-based working fluids such as Freon-22. .

[Table] Fluorinated hydrocarbon-based working fluids have better stability than other organic compounds, so they are used as working fluids for thermosiphons and heat pipes. However, there are considerable differences in stability due to the coexistence of metals, oil, etc. in the working fluid. Table 2
As can be seen, the thermal stability of nFPO was better than that of Freon-12, Freon-22, and Freon-114, and no change in the purity of nFPO was observed. Also
The amount of corrosion of metals that coexist with nFPO is also small (for example, as a result of a comparative experiment in which nFPO, Freon-12, etc. were circulated as working fluids in copper pipes, the amount of corrosion of copper tubes with nFPO was lower than that of Freon-12, etc.). (The amount of corrosion on copper pipes was approximately half of that in the case of copper pipes.) Furthermore, as a result of the experiment, no hydrogen fluoride was generated from the circulation system using nFPO as the working fluid. Based on the known physical properties of nFPO as well as experimental measurement data as described above, nFPO can be used as a heat transfer device of this type.
Focusing on the fact that this is suitable, we conducted an experiment using the thermosiphon shown in the drawing, and found that the working fluid formed a stable closed circulation cycle, achieving an approximately 5% improvement in heat transfer compared to conventional systems. . next
The system of a heat transfer device using nFPO as a working fluid is explained in the drawings. 1 is a regeneration section, 2 is a condensation section, and 3 is a storage section. These are connected by piping 4, 5, and 6 to circulate the working fluid in a closed manner. A thermostat forming a system 7 and sending the condensation latent heat and sensible heat energy of the working fluid to a load side (not shown) outside the system 7 via a radiator 8 surrounding the condensing section 2 by means of cooling water. It constitutes a siphon. And nFPO is used as the working fluid of the thermosiphon. The working fluid heated in the regeneration section 1 evaporates and rises inside the pipe 4 in a gas-liquid two-phase flow that forms a liquid phase part on the inner wall of the pipe 4 and a gas phase part in the hollow part of the pipe 4. Then, it reaches the condensing section 2. The working fluid that has reached the condensing section 2 is cooled by the cooling water flowing through the radiator 8, flows down inside the piping 5, returns to the regeneration section 1 again via the liquid storage section 3 and the piping 6, and the working fluid is returned to the regenerating section 1. Cycle through 7. In this way, the thermal energy of the working fluid is continuously supplied from the condensing section 2 to the load side via the radiator 8. 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 of the working fluid given in the regeneration section from the condensation section to the outside of the system. In a mobile device,
Since nFPO is used as the working fluid, the stability of the working fluid can be maintained even if the heat source supply method to the regeneration section is a direct fire method, and the structural material (metal) of the device is less likely to corrode and is safe. Therefore, the entire device can be made compact. In addition, since nFPO is not flammable, there is little risk of causing a large fire, and the device of the present invention can be used in household hot water supply and heating systems, and is also useful in practice, as it is suitable for use in cold regions. .

[Brief explanation of the drawing]

The drawing is a schematic system diagram of a thermosiphon that is an embodiment of the device of the present invention. 1... Regeneration section, 2... Condensation section, 7... Circulation system.

Claims (1)

[Claims] 1 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, and the thermal energy given to the working fluid in the regeneration section is transferred to the condensation section. In a heat transfer device that sends heat from the air to the outside of the closed circulation system,
A heat transfer device characterized in that the working fluid consists of n-perfluorooctane.