JPS63194189A - Thermosyphon - Google Patents

Abstract

PURPOSE:To obtain a thermosyphon, not generating flooding even when the transporting amount of heat is increased and capable of transporting much amount of heat, by a method wherein an inner tube, whose both ends are opened in a lower evaporating part and an upper condensing part, isolated from the ascending passageway of vapor and forming the flowdown passageway of condensate having a sectional area smaller than the same of the ascending passageway of vapor, is provided in a heat insulating part. CONSTITUTION:An inner tube 6, forming the flowdown passageway of condensate, is provided in a thermosyphon main body 1, consisting of an evaporating part 1a, a heat insulating part 1b and a condensing part 1c, and a condensate collector 4 is provided continuously on the upper part of the inner tube 6 while the upper end thereof is brought in contact with the inside of the main body 1 to collect the condensate, being generated on the inner wall of the tube of the condensing part 1c, and flow down into the inner tube 6. Operating fluid 2 is heated and becomes vapor, ascending through the ascending passageway of vapor between the main body 1 and the inner tube 6, then, passes through an opening 5 and enters into the condensing part 1c. The heat exchange of the vapor, entered into the condensing part 1c, is effected and the vapor is condensed on the inner wall of the tube of the condensing part 1c of the main body 1, then, flows down and collected into a condensate collector 4, thereafter, is returned to the evaporating part 1a through the inner tube 6. The sectional area of the inner tube 6 is small and the inner tube is filled with the condensate without dipping the lower end thereof into the operating fluid 2, therefore, the inner tube will never become the ascending passageway of the vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement of a thermosiphon used in an exhaust heat recovery heat exchanger, etc., and relates to a thermosiphon with a large heat transport capacity.

[Prior Art] A conventional thermosiphon has a structure shown in FIG. 4, in which a working fluid 2 is sealed in a thermosiphon body 1, and condensation is carried out from an evaporating section 1a on a high temperature side to a heat insulating section 1b on a low temperature side. Department IC
The heat is transported to the working fluid 2 through the vapor of the working fluid 2.

The working fluid 2 heated in the evaporator 1a rises as vapor, undergoes heat exchange in the condenser IC, and is condensed.

The condensed liquid 3 flows through the inner wall of the tube and returns to the evaporation section 1a.

In the process of the above cycle, the heat input in the evaporating section 1a is transferred to the condensing section I.
Heat is radiated by C, and heat is transported.

[Problems to be solved by the invention] Conventional thermosiphons have a single-tube structure, so steam rises and condensate flows simultaneously in the same pipe, resulting in a two-phase flow of gas and liquid opposing each other. is formed. For this reason, when the amount of evaporation of the working fluid increases and the rising vapor flow rate reaches a certain value, a so-called flooding phenomenon occurs, in which the condensate is blocked by the vapor flow and stops flowing down. When this flooding phenomenon occurs, the amount of working fluid in the evaporator is extremely reduced, and the amount of heat transported is significantly reduced.

The limit value of heat transport that does not cause flooding is generally expressed by the following equation. This formula is an estimation formula, but Qmax: Heat transport limit value C: Constant L: Latent heat of working fluid S: Channel area g: Gravitational acceleration D = Pipe diameter ρ4 Density of working fluid pQ: Working fluid vapor density Density In the inventor's experiment, the thermosiphon body had a nominal diameter of 20A.
When the working fluid is Freon 113, it is about I KW, when it is water, it is about 4 KW, and when the working fluid is heat transfer oil (trade name Dowsome A), it is about 0.
．． It is 4KW, which almost matches the estimated value. These values indicate that flooding occurs in areas with low heat transport, and there was a misunderstanding that if the above values were used to design a thermosiphon, the equipment would be large.

This invention was made to solve the above-mentioned problems, and the purpose is to obtain a thermosiphon that can transport a large amount of heat without causing a flooding phenomenon even when the amount of heat transport increases. It is.

[Means for Solving the Problems] The present invention has a heat insulating part that has both ends open to a lower evaporating part and an upper condensing part, and is isolated from a steam ascending passage, and has a cross-sectional area smaller than the cross-sectional area of the steam ascending passage. The above problem is solved by providing an inner pipe that forms a condensate flow path with a small area.

[Function] As mentioned above, by providing a flow path for condensate in the heat insulating section, the vapor generated in the evaporation section ascends through the passage with a large cross-sectional area, and the condensate generated in the condensation section passes through the flow path. and reflux to the evaporation section. Since the passages for steam and condensate can be separated in this way, a two-phase flow opposite to that of gas and liquid is not formed, and the flooding phenomenon is also eliminated.

[Example] An embodiment of this invention will be described.

FIG. 1 is a sectional view of a thermosiphon according to the present invention, which is constructed by providing an inner pipe 6 serving as a flow path for condensed liquid in a thermosiphon main body 1 consisting of an evaporating section 1a, a heat insulating section 1b, and a condensing section 1c. There is. A funnel-shaped condensate collector 4 is connected to the upper part of the inner pipe 6, and the upper end of the condensate collector 4 is in close contact with the inside of the main body 1 to collect condensate generated on the inner wall of the condensing part IC. It has a structure that collects the liquid and causes it to flow down into the inner tube 6.

Further, the funnel-shaped lower part of the condensate collector 4 is a liquid reservoir 4a, which is designed to temporarily store the condensate. Further, an opening 5 is provided in the condensate collector 4 to provide a passage for vapor flow leading from the heat insulating part 1b to the condensing part IC.

In the above configuration, the positions of the inner tube 6 and the condensate collector 4 are such that the lower end of the inner tube 6 is near the upper end of the evaporator 1a, and the condensate collector 4
The upper end needs to be near the lower end of the condensing section 1c.

A more preferable mounting position for the inner pipe 6 and the condensate collector 4 is a lower part where the lower end of the inner pipe 6 is 20 to 30 m from the upper end of the evaporation section 1a.
The upper end of the condensate collector 4 is the lower end of the condensing part 1c.

Further, the lower end of the inner tube 6 may or may not be immersed in the working fluid stored in the evaporator 1a.

Next, the effect will be explained.

The working fluid 2 is heated to steam and rises through the steam rising passage between the body 1 and the inner tube 6, as shown by the arrow, and passes through the opening 5 into the condensing section IC. Condensing part I
The steam that entered C undergoes heat exchange, condenses on the inner wall of the condensing part IC pipe of the main body 1, flows down, is collected in the condensate collector 4, and flows into the inner pipe 6, which is a flow path, as shown by the arrow. , and refluxes to the evaporation section 1a.

Since the inner pipe 6 that forms the condensate flow path has a small cross-sectional area, even if the lower end is not immersed in the working fluid 2, part or all of the flow path is filled with condensate, so that steam rises. It will never become a passageway.

Although this embodiment shows a case in which there is one inner pipe 6, the number of inner pipes 6 is not limited to one, and the same effect can be obtained by using a plurality of inner pipes so that the total cross-sectional area of the flow path is the same. effect can be obtained. Further, as shown in FIG. 2, the condensate collector 4 constituting the thermosiphon has a liquid reservoir 4a at the bottom.
It may also have a structure without.

FIG. 3 is a cross-sectional view of another embodiment.
An inner tube 6 is provided close to the inner diameter of the tube. In this embodiment, the inside of the inner pipe 6 is a rising path for steam, and the space between the main body 1 and the inner pipe 6 is a flow path for condensate, and the condensate generated in the condensing part IC flows through the inner wall of the pipe of the condensing part IC. Since the condensate flows down and enters the condensate flow path, a condensate collector as in the embodiment of FIG. 1 is not required.

Further, the shape of the inner tube 6 is not limited to the cylindrical shape as described above, but may be a polygonal shape such as a quadrangular shape or a hexagonal shape.

[Effects of the Invention] By separating the steam ascending path and the condensate flow path, this invention eliminates the flooding phenomenon that occurs in conventional single-tube thermosiphons, and the heat transport limit value is lower than that of the conventional one. Compared to a single-tube type thermosiphon, a value several to ten times higher can be obtained, and it brings about excellent effects such as miniaturization of equipment due to improved capacity.

Next, experimental results comparing the present invention and the conventional technology will be explained.

In the case of the conventional single-tube type, the main body has a total length of 77'I'L1 and a nominal diameter of 2OA, and as a result of experiments using a thermosiphon containing Freon 113 as the working fluid, the heat transport amount is approximately IKW.
reached its limit.

On the other hand, according to the structure shown in FIG. 1 of the present invention, an experiment was conducted by inserting the inner tube 6 with a nominal diameter of 8A into the thermosiphon, and the results showed that it was stable even when the heat transport amount was 7.8KW. It was confirmed that it works.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIGS. 2 and 3 are sectional views showing different embodiments, and FIG. 4 is a sectional view showing a conventional single-tube thermosiphon. DESCRIPTION OF SYMBOLS 1... Main body, 2... Working fluid, 6... Inner pipe, 1a
... Evaporation section, 1b... Heat insulation section, IC... Condensation section. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 1 and 2 Figure 3 Figure 4

Claims (1)

[Claims] In a thermosyphon, which is composed of a lower evaporator section for storing working fluid, an upper condensing section for condensing evaporated vapor, and a tubular heat insulating section connecting these, both ends are connected to the lower evaporator section and the upper condensing section within the heat insulating section. 1. A thermosiphon characterized by having inner pipes each of which is open, separated from a steam rising passage, and forming a condensate flow passage having a cross-sectional area smaller than the cross-sectional area of the steam rising passage.