JPS629184A - Heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a heat exchanger, and more particularly, to a heat exchanger suitable for being incorporated into a heater of a Stirling engine, for example.

[Technical background of the invention and its problems]

Recently, as part of efforts to save energy, the Stirling engine has been reviewed and intensive research is being conducted. There are various types of Stirling engines, for example,
Taking a two-piston type as an example, a regenerative heat exchanger is connected in a closed flow path configuration between power cylinders each containing a built-in power piston, and the flow between one end of the regenerative heat exchanger and one power cylinder is The passage is heated by a heater, and the passage between the other end of the regenerative heat exchanger and the other power cylinder is cooled by a roller.

This engine is characterized by its high theoretical thermal efficiency and the ability to use any heat source.

By the way, the output of a Stirling engine is determined by the maximum space volume created by the movement of the piston inside the cylinder.

Temperature ratio 9 It depends on mechanical efficiency, etc., but it also depends on dead space in heaters, etc., and the smaller the dead space, the smaller the dead space.

Output can be increased. Therefore, as a heat exchanger incorporated in the heater of this engine.

It is desired that the space that can become dead space be as small as possible. However, on the other hand, the higher the heating temperature in the heater, the higher the efficiency, so it is also a necessary condition that the heat exchanger built into the engine heater has a sufficiently large heat transfer area. Become.

For this reason, it has been proposed to use a large number of thin heat transfer tubes with an inner diameter of about 1 to 4 INR to construct a heat exchanger to be incorporated into a Stirling engine heater. however.

This is because a heat exchanger with this configuration requires a large number of thin heat transfer tubes to be connected to the cylinder head.

There are many welding points, which not only makes welding work extremely troublesome, but also causes the working fluid to leak easily due to the large number of welding points.
There was a problem that the device lacked reliability.

Therefore, in order to solve this problem,
As shown in Publication No. 167863, the heat transfer area is increased by using large diameter heat transfer tubes,
In addition, in order to suppress the increase in dead space caused by the use of large diameter heat transfer tubes, a core material is inserted into the heat transfer tubes to increase the channel width (or thickness) in the same direction as the heat transfer direction.
There have also been proposals for heat exchangers that have a smaller size.

A heat exchanger with such a configuration can significantly reduce the number of welding points, unlike a heat exchanger using thin heat exchanger tubes. However, if you try to roughly increase the heat transfer area,
Furthermore, it is necessary to use heat exchanger tubes with a larger diameter or increase the number of heat exchanger tubes, and there is a limit to increasing the heat transfer area within a limited space.

Furthermore, what is common to the two types of heat exchangers mentioned above is how to prevent corrosion of the heat transfer tubes caused by lubricating oil that has entered the working space through the gap between the cylinder and piston. It is. That is, the heat exchanger tubes of the heat exchanger incorporated in the heater of the Stirling engine are usually heated to several 100 degrees Celsius. When the lubricating oil that has entered the working space is heated to the above temperature, it decomposes, and the decomposed components accelerate corrosion of the heat exchanger tubes. Therefore, it was necessary to find a countermeasure against this corrosion.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to simplify welding work, prevent leakage of working fluid, and increase heat transfer area within a limited space. It is an object of the present invention to provide a heat exchanger which is capable of achieving high corrosion resistance and is highly corrosion resistant.

(Summary of the Invention) According to the present invention, there is provided an outer heat transfer tube with one end closed, and a heat transfer core inserted into the outer heat transfer tube.

After being inserted between the heat transfer core material and the outer heat transfer tube and extending between the outer heat transfer tube and the heat transfer core material from the other end side of the outer heat transfer tube toward the one end side.

an inner heat exchanger tube that is folded back at the one end side to form a folded fluid passage extending toward the other end side; and an inner heat exchanger tube formed integrally with the outer surface of the inner heat exchanger tube and at a height close to the inner surface of the outer heat exchanger tube. a plurality of first protrusions dividing a portion of the folded fluid passage located between the inner heat transfer tube and the outer heat transfer tube into a plurality of sections in the circumferential direction; and an inner surface of the inner heat transfer tube or the heat transfer core. A plurality of portions in the circumferential direction are provided integrally on one of the outer surfaces of the material and at a height close to the other and located between the inner heat transfer tube and the heat transfer core material of the folded fluid passage. A heat exchanger is provided, comprising a plurality of partitioning second protrusions, and plating layers provided on the inner surface of the outer heat transfer tube, the inner and outer surfaces of the inner heat transfer tube, and the outer surface of the heat transfer core material. Ru.

〔Effect of the invention〕

According to the present invention, when the outer surface of the outer heat exchanger tube is brought into contact with the high temperature fluid and the low temperature fluid is caused to flow through the above-mentioned folded fluid passage, the heat of the high temperature fluid is transferred from the outer surface of the outer heat exchanger tube to the outer heat exchanger tube and the outer side. The first path consisting of the inner surface of the heat exchanger tube - the low temperature fluid, and the outer surface of the outer heat exchanger tube - the outer heat exchanger tube - the inner surface of the outer heat exchanger tube - the first protrusion - the inner heat exchanger tube - the inner and outer surfaces of the inner heat exchanger tube - the low temperature fluid. and the outer surface of the outer heat exchanger tube ~ the outer heat exchanger tube ~
Inner surface of the outer heat transfer tube - first protrusion - inner heat transfer tube - second protrusion - heat transfer core material - outer surface of the heat transfer core material - third layer made of low-temperature fluid
It is transmitted to the low-temperature fluid through three routes:

Therefore, when compared assuming that the inner diameters of the outer heat exchanger tubes are the same, the heat transfer area can be more than doubled compared to a case in which a core material is inserted to simply form a folded passage in the heat exchanger tube. Therefore, it is possible to improve the heat exchange efficiency while reducing the overall size. Further, by selecting the heights of the first and second protrusions, the width (or thickness) in the same direction as the heat transfer direction in the folded fluid passage can be made sufficiently small without reducing the heat transfer area so much. Therefore, it is possible to create a structure with a small space that can become a dead space. Furthermore, since plating layers are provided on the inner surface of the outer heat transfer tube, the inner and outer surfaces of the inner heat transfer tube, and the outer surface of the heat transfer core material, corrosive components can enter the folded fluid passage by selecting the material for this plating layer. Even in such a case, it is possible to prevent the structural members from being corroded. In this way, it is possible to obtain a heat exchanger that is suitable for being incorporated into a heater of a Stirling engine, etc., since a sufficiently large heat transfer area can be obtained, a space that can become a dead space can be narrowed, and corrosion resistance can be improved. I can do it.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a longitudinal sectional view of a two-piston Stirling engine in which a heat exchanger according to an embodiment of the present invention is incorporated into a heater.

That is, this Stirling engine is broadly divided into a power cylinder 1 (hereinafter referred to as an expansion cylinder) used for expanding one working fluid, and a power piston 2 slidably mounted within the expansion cylinder 1. (Hereafter referred to as the expansion piston.)

Power cylinder 3 (hereinafter referred to as
It is called a compression cylinder. ), a power piston 4 (referred to as a compression piston by Ishitoshi) mounted movably within the compression cylinder 3, and a heater 5 provided between the expansion cylinder 1 and the compression cylinder 3. Connecting rods 8, 9 . It consists of an output shaft 12 connected via a crankshaft 10.11.

The heater 5 includes a combustion chamber 15 formed by arranging a heat insulating material 14 so as to surround the head 13 of the expansion cylinder 1, a plurality of heat exchangers 16 arranged within the combustion chamber 15, and a combustion v15. It is comprised of a burner 17 placed so as to face the engine, and a preheater 18 that preheats the air necessary for combustion with combustion gas.

Each of the heat exchangers 16 has a rod-like outer shape, and one end of each fluid passage communicates with the top of the expansion cylinder 1, and the other end communicates with a manifold 19 formed within the head 13. They are arranged so as to form a funnel as a whole. and.

Each heat exchanger 16 is specifically constructed as shown in FIGS. 2 and 3. That is, this heat exchanger 16
Broadly divided, the outer heat exchanger tube 21 is closed at one end and open at the other end, the inner heat exchanger tube 22 is inserted concentrically into the outer heat exchanger tube 21 and both ends are open, and the inner heat exchanger tube 21 is open at both ends. 22 and a heat transfer core material 23 inserted concentrically therein. The outer heat exchanger tube 21 is made of a material with good thermal conductivity, heat resistance, and pressure resistance, and its inner surface is nickel plated.

Further, a plurality of fins 24 are provided protruding from the tip side of the outer circumferential surface, that is, the closed side. The inner heat exchanger tube 22 is made of a material having better thermal conductivity than the outer heat exchanger tube 21 , for example, copper, and is formed to be longer than the outer heat exchanger tube 21 by a predetermined length, and one end 25 is a predetermined distance from the closed wall of the outer heat exchanger tube 21 . It is inserted into the outer heat exchanger tube 21 such that the other end 26 protrudes from the outer heat exchanger tube 21 while being separated by the same amount. and.

On the outer surface of the inner heat exchanger tube 22, as shown in FIG.
7 is integrally formed. The protrusions 27 are formed at such a height that they come into close contact with the inner surface of the outer heat exchanger tube 21 when the inner heat exchanger tube 22 is inserted into the outer heat exchanger tube 21 as shown in FIG. 5. Further, the inner and outer surfaces of the inner heat exchanger tube 22 are nickel plated. The heat transfer core material 23 is also made of copper or the like and is formed to be slightly longer than the inner heat transfer tube 22. This heat transfer core material 23 has one end 28 connected to the outer heat transfer tube 2.
1, and protrudes from the end 25 of the inner heat exchanger tube 22 by a predetermined distance, and the other end 2
9 is inserted into the inner heat exchanger tube 22 so that it is flush with the end 26 of the inner heat exchanger tube 22, and a protrusion 30, which will be described later, overlaps the position where the protrusion 27 is provided. As shown in FIG. 3, the outer surface of the heat transfer core material 23 has four
Projections 30 extending in the axial direction are integrally formed 6 over the locations. This protrusion 30 is.

When the heat transfer core material 23 is inserted into the inner heat transfer tube 22 as shown in FIG. 2, it is formed at such a height that it comes into close contact with the inner surface of the inner heat transfer tube 22. Further, the outer surface of the heat transfer core material 23 is plated with nickel.

Each heat exchanger 16 configured as described above is welded to the head 13 such that the end 26 of the inner heat exchanger tube 22 communicates with the top in the expansion cylinder 1, as shown in FIG. The open end 31 of the heat tube 21 is welded to the head 13 in communication with the manifold 19 .

Thus, the manifold 19 is connected to the regenerative heat exchanger 6 via the connecting pipe 32, and the regenerative heat exchanger 6 is connected to the top inside the compression cylinder 3 via the cooler 7 constituted by the heat exchanger. ing.

A space surrounded by the expansion cylinder 1 and the expansion piston 2, each heat exchanger 16. Manifold 19° connection pipe 32.
Regenerative heat exchanger6. -1e as a working fluid is sealed in a closed space surrounded by the cooler 7, the compression cylinder 3, and the compression piston 4.

In FIG. 1, numeral 33 indicates a crank chamber containing lubricating oil up to a predetermined level, numerals 34 and 35 indicate linear bearings, and numeral 36 indicates piping for guiding the refrigerant of the cooler 7.

With such a configuration, when the output shaft 12 is temporarily rotated by an external power source while the burner 17 is ignited and the refrigerant is flowing through the pipe 36, the output shaft 12 is connected to the crankshaft 10. 11, the expansion piston 2 and the compression piston 4, which are connected via the connecting rod 8.9, reciprocate with a certain phase difference. When the expansion piston 2 moves to the compression stroke due to this reciprocating movement, He in the expansion cylinder 1 is transferred to each heat exchanger 16. Manifold 19. Connecting pipe 32
．． Regenerative heat exchanger6. It flows into the compression cylinder 3 via the cooler 7, and when the expansion piston 2 reaches the top dead center, H
Most of e flows into the compression cylinder 3. At this time, while the He passes through the regenerative heat exchanger 6, its retained heat is taken away by the regenerative heat exchanger 6, and while it passes through the cooler 7, it is further cooled. When the compression piston 4 begins to move from the bottom dead center toward the top dead center as the output shaft 12 rotates, the low-temperature He in the compression cylinder 3 is compressed, and is moved to the expansion cylinder 1 in the opposite path. Flow inward. At this time, He absorbs heat while passing through the regenerative heat exchanger 6 and is heated to a high temperature, and is further heated while passing through each heat exchanger 16.

The high temperature He that has flowed into the expansion cylinder 1 expands and pushes down the expansion piston 2. Thereafter, the above-described operations are repeated, and even when the external power source is cut off, the output shaft 12 continues to rotate, and functions as a Stirling engine.

By the way, He moves between the expansion cylinder 1 and the compression cylinder 3 as described above.

When this He passes through each heat exchanger 16, it passes through the following route. That is, taking as an example the case where He flows from the manifold 19 toward the expansion cylinder 1, the open end 31 of the outer heat exchanger tube 21 of each heat exchanger 16 communicates with the manifold 19, and the end of the inner heat exchanger tube 22 communicates with the manifold 19. 26 communicates with the top inside the expansion cylinder 1, He indicates the existence of the protrusion 27 between the outer heat exchanger tube 21 and the inner heat exchanger tube 22, as shown by the solid arrow in FIG. Flows along the axis of the passage 41, which is divided into four sections in the circumferential direction, toward the closed wall of the outer heat exchanger tube 21.2. It turned around near the closing wall, and then flowed along the axis through a passage 42 that was divided into four sections in the circumferential direction by the presence of the protrusions 30 between the inner heat transfer tube 22 and the heat transfer core material 23. After that, it flows to the expansion cylinder 1.

Each heat exchanger 16 is located within the combustion chamber 15. Therefore, when He flows through the heat exchanger 16 through the above path,
This He is heated, and in this case, since each heat exchanger 16 is configured as described above, it can be heated efficiently. That is, the heat generated in the combustion chamber 15 is transmitted through a first path consisting of the outer heat exchanger tube 21, the inner surface of the outer heat exchanger tube 21, and He, and the outer heat exchanger tube 21, the inner surface of the outer heat exchanger tube 21, the protrusion 27, and the inner surface. A second path consisting of the inner and outer surfaces of the heat exchanger tube 22 - He, and the outer heat exchanger tube 21 - the inner surface of the outer heat exchanger tube 21 - the protrusion 27 - the inner heat exchanger tube 22 - the inner surface of the inner heat exchanger tube 22 - the protrusion 3
It is transmitted to 1-1e through three routes: 0 to the heat transfer core material 23, the outer surface of the heat transfer core material 23, and a third path consisting of He. Therefore, using a heat exchanger tube that has the same inner diameter as the outer heat exchanger tube 21,
The heat transfer area can be expanded several times compared to a case where a core material is inserted into the heat transfer tube to form a simple folded passage. Therefore, it is possible to improve the exchange efficiency of the heat exchanger 16 and to downsize the entire heat exchanger 16. Furthermore, by simply setting the height of the protrusions 27.30 low, the thickness Y of each passage 41.42 in the same direction as the heat transfer direction can be reduced without substantially reducing the heat transfer area.

The most preferred heat exchanger for Stirling engines,
In other words, it is possible to realize a heat exchanger with a small space that can become a dead space. In addition, since nickel plating is applied to the inner surface of the outer heat transfer tube 21, the inner and outer surfaces of the inner heat transfer tube 22, and the outer surface of the heat transfer core material 23, even if the
Even if lubricating oil enters the heat exchanger, the presence of the plating layer prevents the heat exchanger constituent materials from being corroded, and as a result, the above-mentioned effects can be achieved.

Note that the present invention is not limited to the embodiments described above, and can be modified in various ways. Namely.

In the above embodiment, the protrusions 30 are provided on the heat transfer core material 23, but they may be provided integrally on the inner surface of the inner heat transfer tube 22. Furthermore, the plating layer is not limited to the nickel plating layer, and may be selected depending on the lubricating oil used. Further, the use of the heat exchanger according to the present invention is not limited to Stirling engines, but can of course be used for heat exchange between various fluids. Other 2 Various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

1vI is a longitudinal sectional view of a Stirling engine incorporating a heat exchanger according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a heat exchanger incorporated in a heater of the engine, and FIG. FIG. 3 is a view of the heat exchanger cut along the line XX in FIG. 2 and viewed in the direction of the arrow. 1... Expansion cylinder, 2... Expansion piston, 31°
Compression cylinder, 4... Compression piston, 5... Heater, 6... Regeneration heat exchanger, 7... Cooler, 16...
Heat exchanger. 21...Outer heat exchanger tube, 22...Inner heat exchanger tube, 23.
... Heat transfer core material, 24 ... Fin, 27.30 ... Projection, 41° 42 ... Passage constituting the folded fluid passage.

Claims (3)

[Claims] (1) An outer heat transfer tube with one end closed, a heat transfer core inserted into the outer heat transfer tube, and an outer heat transfer tube inserted between the heat transfer core and the outer heat transfer tube. and the heat transfer core material to form a folded fluid passage that extends from the other end of the outer heat transfer tube toward the one end, is folded back at the one end, and extends toward the other end. a heat exchanger tube, and is formed integrally with the outer surface of the inner heat exchanger tube and at a height close to the inner surface of the outer heat exchanger tube, and is located between the inner heat exchanger tube and the outer heat exchanger tube of the folded fluid passage. A plurality of first protrusions dividing the portion into a plurality of parts in the circumferential direction, and provided integrally with either the inner surface of the inner heat transfer tube or the outer surface of the heat transfer core material and at a height close to the other. a plurality of second protrusions dividing a portion of the folded fluid passage located between the inner heat transfer tube and the heat transfer core material into a plurality of sections in the circumferential direction; A heat exchanger comprising plating layers provided on the inner and outer surfaces of a heat tube and the outer surface of the heat transfer core material. (2) The heat exchanger according to claim 1, wherein the inner heat transfer tube and the heat transfer core material are formed of a material having higher thermal conductivity than the outer heat transfer tube. (3) The heat exchanger according to claim 1, wherein the plating layer is a nickel plating layer.