JPS61210254A - Hot heat exchanger for stirling engine - Google Patents

Abstract

PURPOSE:To reduce the fluidic resistance of combustion gas as well as to improve the extent of heat exchanger effectiveness ever so better, by forming a tube into flatness as well as bending it into U-shaped form, and dislocating each tube part on both inner and outer circumferential sides, while installing each radiator plate between each of tubes themselves at these inner and outer circumferential sides. CONSTITUTION:A tube 11 is formed into flatness and sets the long diameter in a flow direction of hot combustion gas, while it is bent into U-shaped form and set up tubularly in an upper part of a cylinder. And, a tube part 112 at the inner circumferential side and a tube part 113 at the outer circumferential side in the said tube 11 are dislocated as far as an angle theta in the circumferential direction from the center of the said tube with each other, while each of radiator plates 12 and 13 is installed between these tubes 112 and 113 themselves. In addition, the radiator plate 12 is extended up to the vicinity of a long diameter position of the tube part 113 at the outer circumferential side, and the radiator plate 13 is extended up to the vicinity of a long diameter position of the tube part 112 at the inner circumferential side. Furthermore, the hot combustion gas G is made to flow toward the tube part 113 at the outer circumferential side from the tube part 112 at the inner circumferential side.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-temperature heat exchanger used in a Stirling engine, and more particularly to a high-temperature heat exchanger with improved heat exchange efficiency.

(Conventional technology) Although internal combustion engines are small and have high performance, they produce a lot of combustion noise.
Furthermore, there are some drawbacks in terms of eliminating harmful emissions.

External combustion engines are attracting attention as a solution to this difficulty.

The Stirling engine is one type of external combustion engine.

The Stirling engine uses a reciprocating displacer (piston) to perform isovolumic heating, isothermal expansion, isovolume cooling, and isothermal compression of gas in a closed space, and has the following advantages over an internal combustion engine.

There is no explosion sound caused by explosive combustion, so the noise is low.

There is a high degree of freedom in fuel selection, and low-quality oil can be used.

Harmful substances generated during combustion can be easily reduced.

In order to improve the thermal efficiency of the Stirling engine, it is important to improve the heat exchange efficiency of the heating heat exchanger.

As shown in FIG. 3, the conventional high-temperature heat exchanger for a Stirling engine has a cylinder 2 in which a displacer 1 reciprocates.
It has a structure in which a large number of perfect circular tubes 3 are bent into a U-shape. This is placed in the high-temperature combustion gas G, and when the high-temperature combustion gas G flows through the opening of the tube 3, it exchanges heat with the gas flowing inside the tube 3.

(Problems to be Solved by the Invention) In the conventional device described above, in order to efficiently transfer the thermal energy possessed by the high-temperature gas to the gas in the pipe, it is necessary to use a large number of tubes or to make the tubes long, which increases the weight, cost, and occupancy. There was a problem with the volume.

Furthermore, since the structure is such that a large bundle of tubes is provided around the engine, the layout around the engine cannot be freely arranged, and the installation of auxiliaries is restricted.

To improve this drawback, a high-temperature heat exchanger for a Stirling engine is also known, which has a structure in which an elbow plate is provided between the tubes to emit radiant heat.

Referring to FIG. 4, a curved arm plate 5 made of ceramics or a heat-resistant alloy is provided between the perfectly circular tubes 4, and this curved arm plate 5 becomes high temperature when exposed to high-temperature combustion gas G, and radiates heat. is given to tube 4.

However, according to the above-mentioned known structure, the tubes 4 are perfectly circular, and the combustion gas G passing between the tubes 4 is
causes a vortex C downstream of the tube, resulting in a large flow resistance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-temperature heat exchanger for a Stirling engine that improves the above-mentioned drawbacks and improves heat exchange efficiency by reducing flow resistance due to combustion.

(Means for Solving the Problems) The present invention is characterized in that a plurality of tubes are provided in the combustion space formed above the cylinder so as to rise upward from the cylinder to form a cylindrical shape. In a high-temperature heat exchanger for a Stirling engine, fuel is burned inside a shaped tube so that the combustion gas flows to the outside of the tube through the gap between the tubes. The tube part on the inner circumference side and the tube part on the outer circumference side are shifted in the circumferential direction from the front center, and the tube part on the inner circumference side and the tube part on the outer circumference side are bent. An elbow plate is provided between them, and the elbow plate extends to the outer circumferential tube portion and the inner circumferential tube portion.

(Example) This will be explained below using figures.

Referring to FIG. 1.2, in the present invention, the tube 11 is made flat, and its major axis is set in the direction of flow where high-temperature combustion is greatest. The tube 11 has a U-shaped bent structure, and this U-shaped tube 11 is arranged in a cylindrical shape above the cylinder. Bent portion 11 of tube 11. and end portion 11. is circular in this embodiment. The tube portion 112 on the inner circumference side and the tube portion 11 on the outer circumference side of the tube 11 are shifted by an angle θ in the circumferential direction from the front center, and there is a gap between the tube portion 11 □ on the inner circumference side and on the outer circumference side. Tube portion 11. In between, there are respectively provided elbow plates 12 and 13.

The calf plate 12 extends to near the long axis position of the tube portion 11 on the outer peripheral side, and the calf elbow plate 13 extends to near the long axis position of the tube portion 112 on the inner peripheral side. The high-temperature combustion gas G flows from the inner tube portion 11□ to the outer tube portion 11. flows towards.

(Effects of the Invention) Since the present invention is configured as described above, the following effects are achieved.

Since the tube is flat, the flow resistance of the hot gas is low, reducing loss due to resistance.

Since the elbow plate is long, it is difficult for the high temperature to cause eddies in the flow of the gas, and the high temperature also reduces the resistance loss when the gas collides with the tube, so the resistance loss is reduced in this aspect as well.

Easy to manufacture and low cost.

[Brief explanation of drawings]

FIG. 1 is a front view of a tube showing an embodiment of the present invention, FIG. 2 is a layout diagram of a tube showing an embodiment of the present invention, and FIG.
The figure is a cross-sectional view showing a high-temperature heat exchanger portion of a Stirling engine, and FIG. 4 is a cross-sectional view showing a high-temperature heat exchanger of a Stirling engine provided with a calf plate. 11: Tube 12: Elbow plate 13: Elbow plate Figure 1 Figure 2

Claims (1)

[Claims] A plurality of tubes are provided in the combustion space formed above the cylinder so as to rise upward from the cylinder to form a cylindrical shape, and the fuel is burned inside the cylindrical tubes so that the combustion gas fills the gaps between the tubes. In a high-temperature heat exchanger for a Stirling engine, the tube is flat, the tube is bent into a U-shape, and the tube part on the inner circumference side and the tube part on the outer circumference side are used. are offset in the circumferential direction from the center of the cylinder, radiation plates are provided between the tube parts on the inner circumference side and between the tube parts on the outer circumference side, and the radiation plates are arranged between the tube parts on the outer circumference side and the inner circumference side. A high-temperature heat exchanger for a Stirling engine that extends to the side tubes.