JPH0430367Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention relates to an improvement of a high-temperature heat exchanger for a Stirling engine.

(Prior Art) Some high-temperature heat exchangers for Stirling engines transfer heat by circulating high-temperature combustion gas through gaps between a plurality of heater tubes disposed within a combustion chamber. As a conventional technique for improving the heat exchange efficiency of heater tubes, there is a known structure in which a radiator made of a thin plate is disposed in the gaps between a plurality of heater tubes, as shown in Japanese Patent Publication No. 59-34859, for example. It is being

(Problem to be solved by the invention) The radiator is placed between the heater tubes, and most of the part is in the shadow of the heater tube when projected from the flame in the combustion chamber. In other words, it does not become a radiator that receives normal gas radiation, but rather reduces the radiation heat transfer from the flame.

[Structure of the idea]

(Means for Solving the Problems) The heater tube includes a housing forming a combustion chamber and a plurality of heater tubes installed in the combustion chamber, the heater tube has a working gas sealed therein, and a plurality of heater tubes. one open end and the other open end of the are connected to an expansion chamber and a compression chamber provided with an actuating piston, and a large-diameter cylindrical portion, a small-diameter cylindrical portion, and the large-diameter cylindrical portion and the small-diameter cylindrical portion. In a high-temperature heat exchanger for a Stirling engine, the combustion chamber follows the inner shape of the heater tube facing the center of the combustion chamber, and the bottom of the heater tube. A large-diameter cylindrical wall portion and a small-diameter cylindrical wall portion each having a large number of through-holes arranged at positions facing each other at a substantially constant distance; and the large-diameter cylindrical wall portion and the small-diameter cylindrical wall portion. A two-stage cylindrical radiant member made of a metal plate is provided with a horizontal wall between the heater tube and the heater tube, and the heater tube is configured so that the radiant heat from the radiant member heated within the combustion chamber also heats the heater tube. That is.

The main components of the present invention include a housing forming a combustion chamber, a plurality of heater tubes, and a two-stage cylindrical radiant member.

The housing defines a combustion chamber. This combustion chamber is a high-temperature chamber in which fuel supplied from the outside is mixed with air and combusted. The plurality of heater tubes constitute a heat exchanger, which is disposed within the combustion chamber, absorbs combustion heat within the combustion chamber, and heats the pressure-operated gas sealed within the heater tube. The two-stage cylindrical radiating member includes a large-diameter cylindrical wall portion and a small-diameter cylindrical wall portion each having a large number of through holes, and a horizontal wall portion between the large-diameter cylindrical wall portion and the small-diameter cylindrical wall portion. Thus, each wall portion is heated by the combustion heat of the combustion chamber and efficiently provides radiant heat to the heater tube at the opposing position. It is preferable that the diameters of the numerous through holes of the cylindrical radiating member are substantially uniform, and that the total area thereof is larger than the total area of the gaps between the heater tubes. Specifically, the total area of the through holes is calculated by multiplying the diameter of the through holes by the number of through holes. The two-stage cylindrical radiating member may be made of a perforated plate or a mesh having substantially uniform through holes over its entire surface. The shape of the hole formed in the two-stage cylindrical radiating member may be circular, approximately circular, elongated, rectangular,
Various other shapes, including polygons, are contemplated. The shape and size of the holes are preferably such that the flow resistance of the combustion gas is small and, conversely, the radiation area is large. The two-stage cylindrical radiating member can be formed by press working a perforated steel plate with large and small cylindrical parts and an annular disc part. Note that each part may be integrally formed by combining or welding.

(Operation) In the combustion chamber of the housing, the two-stage cylindrical radiant member is arranged at the center of the heater tube.
Therefore, in the combustion chamber, the two-stage cylindrical radiant member is first heated by the combustion gas. Thereafter, the combustion gas that heated the two-stage cylindrical radiant member heats the heater tube. Note that the heated two-stage cylindrical radiant member emits radiant heat and directly heats the heater tube by hot ray radiation.

(Example) An example of the present invention will be described based on FIGS. 1 and 2.

The two-stage cylindrical radiant member A is installed in a combustion chamber C within a housing E, as shown in FIG.
That is, it is arranged on the inner side facing the center of the combustion chamber C and along the inner side of the plurality of heater tubes 4 arranged along the inner circumferential wall C1 of the combustion chamber C. . The plurality of heater tubes 4 are filled with high-pressure working gas. One open end 41 and the other open end 42 of the heater tube 4 are connected to an expansion chamber 412 and a compression chamber 42a each provided with an actuating piston (not shown). Further, the plurality of heater tubes 4 are arranged in a shape consisting of a large diameter cylindrical part 44, a small diameter cylindrical part 46, and a horizontal bottom part 45 between the large diameter cylindrical part 44 and the small diameter cylindrical part 46. ing.

The two-stage cylindrical radiating member A made of a metal plate includes a large-diameter cylindrical wall portion 1, a small-diameter cylindrical wall portion 3, and a horizontal wall portion 2.
are arranged at positions facing the large-diameter cylindrical portion 44, the small-diameter cylindrical portion 46, and the horizontal bottom portion 45 formed by the plurality of heater tubes 4, respectively. Note that the two-stage cylindrical radiating member A is composed of, for example, an annular horizontal wall portion 2 that connects the large diameter cylindrical wall portion 1 and the upper end portion 3a of the small diameter cylindrical wall portion 3. A large number of through holes a are formed in the large diameter cylindrical wall portion 1, the small diameter cylindrical wall portion 3, and the annular horizontal wall portion 2 that constitute the two-stage cylindrical radiating member A. The outer diameters d1 and d2 of both the cylindrical wall portions 1 and 3 are set to be smaller than the inner diameters d'1 and d'2 formed by the plurality of heater tubes 4, respectively, by about 1 cm. Further, the height H2 of the cylindrical portion 3 is set to be approximately 5 mm away from the bottom surface 4b of the heater tube 4, as shown in FIG. Further, the height H1 of the cylindrical portion 1 is set to approximately coincide with the top portion 4a of the heater tube 4.

Here, fuel is injected into the combustion chamber C by the injection valve 5. At the same time, the incoming air from the outside flows into the inflow passage 6a of the air preheater element 6.
is introduced into the burner tile 8 while being swirled by the swirler 7. As a result, the fuel and air become a mixture, which is ignited within the burner tile 8 by an ignition device (not shown).
Thereafter, fuel and air continue to be supplied into the fuel chamber C, and the fuel continues to burn in the space of the two-stage cylindrical radiant member. Therefore, the flame during combustion is surrounded by the two-stage cylindrical radiant member. The two-stage cylindrical radiant member is heated by flame radiation and convection heat transfer. The heated two-stage cylindrical radiant member A transfers radiant heat between the outer heater tubes 4 as the temperature rises. In addition, high-performance heat transfer is performed to the heater tube 4, and the temperature of the two-stage cylindrical radiant member A itself is maintained at a temperature slightly higher than that of the heater tube 4. Next, the combustion gas flows out to the heater tube 4 side through each hole a group of the two-stage cylindrical radiant member A, and gives heat to the heater tube 4 by convection heat transfer, and then the combustion exhaust gas is air preheated. Combustion air passes through the outflow passage 6b of the element 6 of the vessel, imparts heat to the combustion air, and after exchanging heat, is exhausted.

In this way, according to the present invention, the amount of heat transferred to multiple heater tubes can be increased without increasing flow loss, and the combustion exhaust gas temperature can also be lowered, making it possible to make the entire heater tube more compact. Therefore, the volume of the combustion chamber can be made sufficiently large, and the efficiency of the Stirling engine can be improved.

(Effects) In order to eliminate the drawbacks of the conventional technology, a ceramic structure is placed inside the combustion chamber, and a ceramic cylinder with pores is placed to blow combustion gas into the heater tube, thereby increasing the heat transfer performance of the high-temperature heat exchanger. I can think of a way. However, in the case of ceramic structures, fixing methods are difficult. Furthermore, if the ceramic structure is integrally molded and the shape is not simple, such as a small-diameter cylinder or a small-diameter flat plate, the ceramic structure will be damaged due to internal thermal stress. Furthermore, the use of a ceramic cylinder or the like having pores increases the pressure inside the combustion chamber, making it necessary to increase the fuel supply pressure and air supply pressure, resulting in an increase in power consumption. In the case of the present invention, (1) Since the two-stage cylindrical radiating member is placed near the heating surface of the heater tube, the two-stage cylindrical radiating member receives heat from the flame and at the same time radiates heat to the heat transfer surface of the heater tube. do. Therefore, the temperature of the two-stage cylindrical radiating member itself can be maintained at 1000° C. or less, it can be manufactured from a relatively inexpensive metal material, and its durability can be increased.

(2) The second stage cylindrical radiating member is a thin plate (approximately 2.0 mm thick)
It can be made from a metal material that generates little internal thermal stress, and the material will not be destroyed by the thermal stress.

(3) Since the total opening area of the holes in the two-stage cylindrical radiant member is larger than the total area of the gaps between the heater tubes, the pressure inside the combustion chamber does not become high.

(4) When such a two-stage cylindrical radiant member is installed in a combustion chamber, the combustion body in the combustion chamber is surrounded by the second-stage cylindrical radiant member due to radiant heat from the second-stage cylindrical radiant member. The combustion reaction is promoted in the space created by the fuel, and complete combustion can be achieved.

(5) According to the present invention, when compared with the conventional configuration in which radiant heat and convection heat transfer of combustion gas is performed to the heater tube in the combustion chamber, the heater tube is placed inside the heater tube facing the center of the combustion chamber. The solid radiant heat of the provided two-stage cylindrical radiant member has an effect of promoting heat transfer to the heater tube, so the heat exchange efficiency is improved, and the heater tube as a whole can be made more compact.

According to the present invention, the above-mentioned characteristic effects can be achieved.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams showing one embodiment of the present invention, in which FIG. 1 is a perspective view of the appearance of the main part, and FIG. 2 is a longitudinal cross-sectional view showing an example of the use of the main part. A... Two-stage cylindrical radiating member, a... Hole, 1...
Large diameter cylindrical part, 2... Annular disc part, 3... Small diameter cylindrical part, 4... Heater tube.

Claims (1)

[Claims for Utility Model Registration] (1) A housing forming a combustion chamber, and a plurality of heater tubes installed in the combustion chamber, the heater tubes having a working gas sealed therein, and a plurality of heater tubes installed in the combustion chamber. One open end and the other open end of the heater tube are connected to an expansion chamber and a compression chamber provided with an operating piston, and a large-diameter cylindrical portion, a small-diameter cylindrical portion, and a large-diameter cylindrical portion connected to the large-diameter cylindrical portion. In a high temperature heat exchanger for a Stirling engine which is arranged in a shape consisting of a horizontal bottom part between a small diameter cylindrical part, the combustion chamber follows the inner shape of the heater tube facing the center of the combustion chamber, and A large-diameter cylindrical wall portion and a small-diameter cylindrical wall portion each having a large number of through holes disposed at a position facing each portion of the heater tube at a substantially constant distance, and the large-diameter cylindrical wall portion and the A two-stage cylindrical radiant member made of a metal plate consisting of a horizontal wall portion between a small-diameter cylindrical wall portion, and radiant heat from the radiant member heated within the combustion chamber also heats the heater tube. A high-temperature heat exchanger for a Stirling engine characterized by the following configuration. (2) The diameters of the numerous through holes of the two-stage cylindrical radiating member made of metal plates are almost uniform, and the total area is larger than the total area of the gaps between each heater tube. A high-temperature heat exchanger for a Stirling engine according to item 1.