Stirling engine

Abstract

To avoid retention of condensation water while it comes into contact with a heater pipe, and improve heat transfer performance from steam to the heater pipe.SOLUTION: A Stirling engine includes: a thermosiphon that accommodates a heating medium receiving heat from a heat source; a body that accommodates work gas; and a heater that is disposed in the body and applies heat to the work gas by using the heating medium. The heater includes: at least one heater pipe in which the work gas flows; and a condensation water discharge port for discharging condensation water condensed from steam as the heating medium supplied from the thermosiphon. The condensation water discharge port is located below the heater pipe.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a Stirling engine. [Background technology]

[0002] For example, Patent Document 1 discloses a device in which a heat exchanger is provided in a duct through which exhaust air passes, which converts water into steam using heat in the exhaust air, and the steam is guided to a heated object, which is then heated by the heat of condensation. The above heat exchanger, which uses water as a medium (heat medium) for heat exchange, is also called a thermosiphon. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-101299 A Summary of the Invention [Problem to be solved by the invention]

[0004] After the heated object (e.g., a heater tube) is heated by the heat of condensation of the water vapor, the water (condensed water) condensed from the water vapor by the release of the heat of condensation is returned to the heat exchanger through a pipe. In Patent Document 1, the connection port (condensed water inlet) of the above-mentioned pipe is at the same height as the lower part of the heater tube, so the condensed water is likely to remain in contact with the lower part of the heater tube until it is drained into the above-mentioned pipe. If the condensed water remains in contact with the heater tube, there is a risk that the heat transfer to the heater tube will decrease.

[0005] The present invention has been made to solve the above problems, and an object of the present invention is to provide a Stirling engine that can prevent condensed water from being retained in contact with the heater tube and improve heat transfer from steam to the heater tube. [Means for solving the problem]

[0006] A Stirling engine according to one aspect of the present invention is a Stirling engine comprising: a thermosiphon that contains a heat medium that receives heat from a heat source; a main body that contains a working gas; and a heater that is disposed within the main body and imparts the heat to the working gas by the heat medium, the heater having at least one heater tube through which the working gas flows, and a condensed water outlet for discharging condensed water condensed from steam as the heat medium supplied from the thermosiphon, the condensed water outlet being positioned below the heater tube. Effect of the Invention

[0007] According to the above configuration, it is possible to prevent the condensed water from remaining in contact with the heater tube, thereby improving the heat transfer from the steam to the heater tube. [Brief description of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of a Stirling engine according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an explanatory diagram showing changes in pressure and volume in an expansion space within the main body of the Stirling engine. [Diagram 3] FIG. 4 is an explanatory diagram showing changes in pressure and volume in a compression space in the main body. [Figure 4] FIG. 2 is a perspective view showing details of the thermosiphon and heater configuration. [Diagram 5] FIG. 2 is a cross-sectional view of the thermosiphon and the heater. [Figure 6] FIG. 4 is an explanatory diagram showing another configuration of the thermosiphon. [Figure 7] FIG. 11 is an explanatory diagram showing still another configuration of the thermosiphon. [Figure 8] 4 is a cross-sectional view showing another example of the arrangement of heater tubes of the heater. FIG. [Figure 9] FIG. 2 is an explanatory diagram illustrating a schematic connection relationship between the main body and the thermosiphon. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

[0010] <1. Basic structure of Stirling engine> 1 is an explanatory diagram showing a basic configuration of a Stirling engine 100 according to an embodiment of the present invention. The Stirling engine 100 includes a thermosiphon 1 and an engine unit 20.

[0011] (1-1. Thermosyphon) Thermosiphon 1 contains a heat medium that receives heat from a heat source HS. The heat source HS can be, for example, factory waste heat. The heat source HS may also be solar heat or geothermal heat. The heat source HS moves through a flow path FP. The flow path FP is, for example, composed of a heat exhaust pipe.

[0012] Thermosiphon 1 has a first pipe 1a, a second pipe 1b, and a third pipe 1c as pipes through which a heat medium flows. First pipe 1a is located inside flow path FP. Second pipe 1b and third pipe 1c are located outside flow path FP. Thus, a portion of thermosiphon 1 is disposed in flow path FP.

[0013] The second pipe 1b is located downstream of the first pipe 1a in the direction in which the heat medium flows. The first pipe 1a and the second pipe 1b are connected via a first connection part 11. The first connection part 11 is provided on a wall surface of the flow path FP. The end of the second pipe 1b opposite to the end connected to the first pipe 1a is connected to an upper part of the main body 30 of the engine part 20.

[0014] The third pipe 1c is located upstream of the first pipe 1a in the direction in which the heat medium flows. The first pipe 1a and the third pipe 1c are connected via a second connection part 12. The second connection part 12 is provided on the wall surface of the flow path FP. The end of the third pipe 1c opposite to the end connected to the first pipe 1a is connected to the lower part of the main body 30.

[0015] The heat transfer medium contained in the thermosiphon 1 is, for example, water. Water is liquid at room temperature, but at high temperatures it boils and turns into gaseous steam. Steam also condenses into water (condensed water). Therefore, steam and condensed water are also included in the heat transfer medium. The heat transfer medium, in either a liquid or gaseous state, flows through the piping of the thermosiphon 1 and circulates between the heat source HS (flow path FP) and the engine section 20.

[0016] More specifically, when the heat medium (here, water) in the first pipe 1a is heated by the heat source HS (for example, exhaust heat), the water evaporates and becomes steam. The steam passes from the first pipe 1a through the second pipe 1b and is introduced from above into the main body 30 of the engine section 20. The steam releases condensation heat to a heater 40 (described later) in the main body 30, thereby heating the heater 40. After releasing the condensation heat, the steam condenses and becomes water (condensed water). The water is discharged from the bottom of the main body 30 and passes through the third pipe 1c, and is returned to the first pipe 1a. In other words, the condensed water enters the flow path FP of the heat source HS. The above process is repeated thereafter. The heat medium contained in the thermosiphon 1 may be a liquid other than water (for example, alcohol).

[0017] In this way, the thermosiphon 1 receives heat from the heat source HS and exchanges heat with the heater 40. Such a thermosiphon 1 is also called a primary heat exchanger.

[0018] (1-2. Engine Configuration) The engine section 20 has a main body 30. The main body 30 is a cylinder that contains a working gas G. The working gas G is, for example, helium. Since helium has a large specific heat capacity, engine output per volume can be increased by increasing the density by applying high pressure to the helium. The working gas G may be a gas other than helium (for example, air, hydrogen, etc.). Within the main body 30, a heater 40, a cooler 50, and a regenerator 60 are arranged linearly in the horizontal direction.

[0019] The heater 40 is formed of, for example, a shell-and-tube type heat exchanger. The heater 40 is also referred to as a secondary heat exchanger in comparison with the thermosiphon 1 which is a primary heat exchanger. The heater 40 has a heater tube 41 through which the working gas G flows. The heater tube 41 is, for example, a metal tube. The metal constituting the heater tube 41 may be appropriately selected from metals with excellent thermal conductivity, such as aluminum, copper alloy, and stainless steel. In this embodiment, a plurality of heater tubes 41 are provided, but it is sufficient that at least one heater tube 41 is provided.

[0020] Steam introduced from thermosiphon 1 into main body 30 flows around each heater tube 41. This heats each heater tube 41, and the working gas G flowing inside each heater tube 41 is heated. In other words, heater 40 imparts heat transferred by the heat medium of thermosiphon 1 to working gas G.

[0021] One end of the heater 40 communicates with the expansion space ES, and the other end communicates with one end of the regenerator 60. That is, the heater 40 is located between the expansion space ES and the regenerator 60 within the main body 30. The expansion space ES is a space in which the working gas G expands when it is heated by the heater 40.

[0022] The cooler 50 is also configured with a shell-and-tube type heat exchanger similar to the heater 40. That is, the cooler 50 has a cooling pipe 51 through which the working gas G flows. The cooling pipe 51 is a metal pipe similar to the heater pipe 41. In this embodiment, a plurality of cooling pipes 51 are provided, but it is sufficient that at least one cooling pipe is provided.

[0023] When a refrigerant is supplied to the cooler 50 from the cooling equipment 70 installed outside the main body 30 via the refrigerant piping 71, the refrigerant flows around each cooling tube 51. This cools each cooling tube 51, and the working gas G flowing through each cooling tube 51 is cooled. In other words, the cooler 50 cools the working gas G with the refrigerant. The above refrigerant is, for example, water, but a refrigerant other than water may also be used. The refrigerant flows through the refrigerant piping 71 and circulates between the cooler 50 and the cooling equipment 70.

[0024] One end of the cooler 50 communicates with the compression space CS, and the other end of the cooler 50 communicates with the other end of the regenerator 60. That is, the cooler 50 is located between the regenerator 60 and the compression space CS within the main body 30. The compression space CS is a space where the working gas G is compressed by a compression piston CP described later.

[0025] The regenerator 60 is disposed between the heater 40 and the cooler 50. The regenerator 60 is formed, for example, of a mesh-shaped flow path. This allows the working gas G in the main body 30 to circulate between the expansion space ES side and the compression space CS side via the regenerator 60. In other words, the regenerator 60 allows the working gas G to circulate between the expansion space ES and the compression space CS. Note that the regenerator 60 is not limited to a mesh-shaped flow path. For example, the regenerator 60 can also be formed of a heat storage material such as a laminated wire mesh, a thin plate aligned with the flow, or a porous body.

[0026] An expansion piston EP serving as a power piston PP is disposed in the main body 30 on the opposite side of the expansion space ES to the heater 40. Also, a compression piston CP serving as a power piston PP is disposed in the main body 30 on the opposite side of the compression space CS to the cooler 50. That is, in the main body 30, the expansion piston EP is disposed via the heater 40 and the expansion space ES of the working gas G, and the compression piston CP is disposed via the cooler 50 and the compression space CS of the working gas G. Thus, a two-piston type Stirling engine 100 having two pistons (expansion piston EP, compression piston CP) serving as a power piston PP is also called an α-type Stirling engine.

[0027] Piston rings PR are fitted around the outer periphery of the expansion piston EP and the compression piston CP. The piston rings PR act as a gas seal. In other words, the piston rings PR prevent leakage of the working gas G from the gap between the expansion piston EP and the main body 30 and the gap between the compression piston CP and the main body 30 (gas leakage).

[0028] An expansion-side piston rod 81 of the expansion piston EP is connected to an expansion-side crosshead piston 82. The expansion-side crosshead piston 82 is connected to an expansion-side crankshaft 84 via an expansion-side connecting rod 83. The expansion-side piston rod 81 is provided penetrating one end face 30a of the main body 30. Therefore, the expansion-side crosshead piston 82, the expansion-side connecting rod 83, and the expansion-side crankshaft 84 are located outside the main body 30.

[0029] The expansion-side crosshead piston 82, the expansion-side connecting rod 83, and the expansion-side crankshaft 84 constitute an expansion-piston-side crank mechanism 85. The expansion piston EP is connected to the expansion-piston-side crank mechanism 85 via the expansion-side piston rod 81. On one end surface 30a of the main body 30, an expansion-side gas seal portion 31a is provided around a through hole through which the expansion-side piston rod 81 passes.

[0030] A compression-side piston rod 86 of the compression piston CP is connected to a compression-side crosshead piston 87. The compression-side crosshead piston 87 is connected to a compression-side crankshaft 89 via a compression-side connecting rod 88. The compression-side piston rod 86 is provided penetrating the other end face 30b of the main body 30. Therefore, the compression-side crosshead piston 87, the compression-side connecting rod 88, and the compression-side crankshaft 89 are located outside the main body 30.

[0031] The compression side crosshead piston 87, the compression side connecting rod 88, and the compression side crankshaft 89 constitute a compression piston side crank mechanism 90. The compression piston CP is connected to the compression piston side crank mechanism 90 via a compression side piston rod 86. On the other end surface 30b of the main body 30, a compression side gas seal portion 31b is provided around a through hole through which the compression side piston rod 86 passes.

[0032] The expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are connected to each other so as to be capable of transmitting power through a power transmission unit 91. More specifically, the expansion side crankshaft 84 of the expansion piston side crank mechanism 85 is connected to the output shaft SH through a first belt 92 so as to be capable of transmitting power. Furthermore, the compression side crankshaft 89 of the compression piston side crank mechanism 90 is connected to the output shaft SH through a second belt 93 so as to be capable of transmitting power. In other words, the first belt 92, the output shaft SH, and the second belt 93 constitute the above-mentioned power transmission unit 91. Note that the power transmission unit 91 may be configured to have a chain, gears, etc., other than or in addition to the belt.

[0033] The output shaft SH is, for example, a rotating shaft of a work machine M. The work machine M is composed of, for example, a generator and a motor. For example, the work machine M operates as a motor only at start-up, and operates as a generator after independent operation.

[0034] (1-3. Engine operation) In the above configuration, when steam flowing through the first pipe 1a and the second pipe 1b of the thermosiphon 1 is introduced into the main body 30 of the engine section 20, the heat of condensation of the steam is imparted to the heater 40, heating the heater 40. The heating of the heater 40 heats the working gas G in the heater tube 41. As a result, the working gas G expands, increasing the pressure in the expansion space ES and pressing against the expansion piston EP. Here, the pressure in the expansion space ES is defined as P E (Pa), and the volume of the expansion space ES is V E (m 3 ), the work load in the expansion process is W E (J) is W E =∫P E dV E It is expressed as:

[0035] As the expansion piston EP is pressed and moved, the expansion-side piston rod 81 and the expansion-side crosshead piston 82 rotate the expansion-side crankshaft 84 in the positive direction via the expansion-side connecting rod 83. The rotation of the expansion-side crankshaft 84 rotates the first belt 92, causing the output shaft SH to rotate in the positive direction. When the output shaft SH rotates, the second belt 93 rotates, causing the compression-side crankshaft 89 to rotate in the positive direction.

[0036] By the rotation of the compression side crankshaft 89, the compression side connecting rod 88 presses the compression side crosshead piston 87 and the compression side piston rod 86, and pushes the compression piston CP into the main body 30. As a result, the compression space CS is compressed, and the working gas G in the compression space CS flows into the cooler 50, and the working gas G is cooled by the cooler 50. Here, the pressure in the compression space CS is expressed as P C (Pa), and the volume of the compression space CS is V C (m 3 ), the work load in the compression process is W C (J) is W C =-∫P C dV C It is expressed as:

[0037] Therefore, when the amount of work required to rotate the output shaft SH (for example, the amount of work required to generate electricity) is W (J), the amount of work W is calculated by multiplying the amount of work W during the expansion process by the following equation: E and the work load in the compression process W C and a predetermined mechanical efficiency η of the engine unit 20, the following equation is used: W = (W E +W C )·η=(∫P E dV E -∫P C dV C )·η

[0038] The expansion and compression steps are repeated by the reciprocating movements of the expansion piston EP and the compression piston CP. At this time, the pressure P E and volume V E In the compression space CS, the pressure PC and volume V C This changes as shown in FIG.

[0039] (1-4. Timing) As described above, the power imparted to the expansion piston side crank mechanism 85 by the movement of the expansion piston EP shown in FIG. 1 is transmitted to the compression piston side crank mechanism 90 via the first belt 92, the output shaft SH, and the second belt 93.

[0040] Here, the expansion piston EP and the compression piston CP reciprocate within the main body 30 with a predetermined phase difference. The phase difference corresponds to the difference between the crank angle of the expansion piston-side crank mechanism 85 and the crank angle of the compression piston-side crank mechanism 90. Therefore, for example, when the rotation angle (crank angle) of the expansion-side crankshaft 84 from a reference position is θ (°), the rotation angle (crank angle) of the compression-side crankshaft 89 from a reference position is expressed as (θ-β), where β (°) is a phase lag. The phase lag β is, for example, 90°, but is not limited to 90°.

[0041] The expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are pre-timed to realize the above-mentioned phase difference. Such timing can be achieved, for example, by connecting the expansion side crankshaft 84 to the output shaft SH via a first belt 92 at a predetermined rotational position, and connecting the compression side crankshaft 89 to the output shaft SH via a second belt 93 at a predetermined rotational position.

[0042] Specifically, the expansion side crankshaft 84 and the first belt 92 are provided with marks for alignment. The compression side crankshaft 89 and the second belt 93 are provided with marks for alignment. Therefore, by aligning the marks of the expansion side crankshaft 84 and the first belt 92 and connecting them, and aligning the marks of the compression side crankshaft 89 and the second belt 93 and connecting them, the expansion side crankshaft 84 can be connected to the output shaft SH via the first belt 92 at a predetermined rotational position, and the compression side crankshaft 89 can be connected to the output shaft SH via the second belt 93 at a predetermined rotational position. The first belt 92 and the second belt 93 used at this time are preferably toothed belts, i.e., timing belts. In this manner, timing is performed. That is, the expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are connected to each other via the power transmission unit 91 so as to be capable of timing.

[0043] In this embodiment, the expansion piston side crank mechanism 85 and the compression piston side crank mechanism 90 are connected via the power transmission unit 91 so as to be capable of transmitting power and adjusting timing, but it is sufficient that they are connected so as to enable at least one of power transmission and timing.

[0044] <2. Thermosyphon and heater details> (2-1. Thermosyphon details) Fig. 4 is a perspective view showing the detailed configuration of thermosiphon 1 and heater 40. Fig. 5 is a cross-sectional view of thermosiphon 1 and heater 40. In Fig. 4, case 40a of heater 40 is shown by a dashed line in order to clarify the internal configuration of case 40a. Thermosiphon 1 and heater 40 will be described in detail below.

[0045] For the convenience of the following description, the directions are defined as follows. First, when the heater 40 is elongated in one direction, the one direction is defined as the front-rear direction, one side of the one direction is defined as the "front", and the other side is defined as the "rear". Of the two directions perpendicular to each other in a plane perpendicular to the front-rear direction, the direction of gravity is defined as the up-down direction, and the remaining direction perpendicular to the direction of gravity is defined as the left-right direction. In this case, the upstream side of the direction of gravity is defined as the "up" direction, and the downstream side is defined as the "down" direction. In addition, of the left-right direction, the right side from the rear to the front is defined as the "right" direction, and the left side is defined as the "left" direction. In the drawings, the front is indicated by the symbol "F", the rear by the symbol "B", the right side by the symbol "R", the left side by the symbol "L", the upper side by the symbol "U", and the lower side by the symbol "D" as necessary.

[0046] The second pipe 1b of the thermosiphon 1 has a main pipe 13 and multiple branch pipes 14. The main pipe 13 is a part of the second pipe 1b that is located above the heater 40. Since the main pipe 13 constitutes part of the second pipe 1b, the heat medium (steam) that receives heat from the heat source HS (see FIG. 1) and flows through the second pipe 1b flows through the main pipe 13. The main pipe 13 extends in the axial direction of the heater 40, that is, in the axial direction of the heater tube 41 (referred to as the front-to-rear direction in this case).

[0047] The multiple branch pipes 14 are provided by branching off from the main pipe 13. Each branch pipe 14 extends downward from the main pipe 13 and is connected to a heater 40. The multiple branch pipes 14 are arranged side by side in the direction in which the main pipe 13 extends, that is, in the axial direction of the heater tubes 41. This structure in which the multiple branch pipes 14 are provided by branching off from the main pipe 13 is also called a header structure.

[0048] The third piping 1c of the thermosiphon 1 has a communicating pipe 15 and a plurality of condensed water pipes 16. The communicating pipe 15 is a part of the third piping 1c that is located below the heater 40. The communicating pipe 15 extends in the axial direction of the heater 40, i.e., in the axial direction of the heater pipe 41.

[0049] The multiple condensate pipes 16 are pipes through which condensate generated inside the heater 40 flows, and are each connected to a condensate discharge port 43 (described later) of the heater 40. Each condensate pipe 16 extends downward from the condensate discharge port 43 and is connected to the communicating pipe 15. The multiple condensate pipes 16 are arranged side by side in the direction in which the communicating pipe 15 extends, i.e., in the axial direction of the heater pipe 41.

[0050] (2-2. Heater details) The heater 40 has, in addition to the above-mentioned at least one heater tube 41, a steam inlet 42 and a condensed water outlet 43. The steam inlet 42 and the condensed water outlet 43 are provided in a cylindrical case 40a that constitutes the outer wall of the heater 40. The steam inlet 42 is located above the condensed water outlet 43.

[0051] The steam inlets 42 are provided corresponding to the plurality of branch pipes 14, respectively, and are connected to the plurality of branch pipes 14. Therefore, in the case 40a, the steam inlets 42 are positioned side by side in the axial direction of the heater tube 41, similar to the plurality of branch pipes 14.

[0052] The condensed water discharge ports 43 are provided corresponding to the multiple condensed water pipes 16, respectively, and are connected to the multiple condensed water pipes 16. Therefore, in the case 40a, the condensed water discharge ports 43 are positioned side by side in the axial direction of the heater tube 41, similar to the condensed water pipes 16. Each condensed water discharge port 43 is positioned in the lower part of the case 40a.

[0053] In particular, the condensed water discharge port 43 is located below the lowermost heater tube 41. For example, as shown in Fig. 5, when the height position of the bottom of the heater tube 41 located at the lowermost position in the case 40a is H0, each condensed water discharge port 43 is provided at a position in the case 40a that is lower than the height H0.

[0054] In the above configuration, steam as a heat medium supplied from thermosiphon 1 flows through main pipe 13, and then branches into multiple branch pipes 14. The steam flowing through each branch pipe 14 is introduced into heater 40 (case 40a) from above via steam inlet 42. Inside heater 40, the steam releases heat of condensation to heater tube 41, thereby heating heater tube 41.

[0055] On the other hand, when the steam releases condensation heat to the heater tube 41, the steam condenses to become condensed water. The condensed water generated inside the heater 40 moves downward by gravity and is discharged from each condensed water discharge port 43 to each condensed water pipe 16. The condensed water discharged to each condensed water pipe 16 joins together at the communicating pipe 15 and then flows downstream (toward the second connection part 12). In other words, the condensed water discharged from each condensed water discharge port 43 returns to the first pipe 1a via the third pipe 1c (see FIG. 1).

[0056] In this embodiment, condensed water generated in the case 40a is discharged from a condensed water discharge port 43 located below the heater tube 41 located at the lowest position. This makes it difficult for the condensed water to remain in contact with the heater tube 41 located at the lowest position in the case 40a. As a result, the heater tube 41 located at the lowest position in the case 40a can be sufficiently contacted with steam, similar to the remaining heater tubes 41, and the heat transfer to the heater tubes 41 can be improved. As a result, all of the heater tubes 41 can be efficiently heated.

[0057] In order to efficiently heat the heater tube 41 extending in the axial direction, it is desirable to heat the heater tube 41 at multiple locations in the axial direction. In this embodiment, multiple branch pipes 14 branched off from the main pipe 13 are arranged side by side in the axial direction of the heater tube 41. The heater 40 has steam inlets 42 connected to the multiple branch pipes 14. In this configuration, the multiple steam inlets 42 are arranged side by side in the axial direction of the heater tube 41, so that steam introduced from the multiple steam inlets 42 can be applied to multiple locations in the axial direction of the heater tube 41, making it easy to heat the heater tube 41 at multiple locations in the axial direction.

[0058] (2-3. About bulkheads) As shown in Fig. 4 and Fig. 5, in this embodiment, the heater 40 further has a partition wall 44. The partition wall 44 is a disk-shaped member having through holes 44a through which the heater tubes 41 pass. In the partition wall 44, the number of through holes 44a is equal to the number of heater tubes 41 in the case 40a. A plurality of such partition walls 44 are provided in the case 40a of the heater 40. Note that only one partition wall 44 may be provided in the case 40a.

[0059] The partition walls 44 are arranged side by side at intervals in the axial direction of the heater tube 41. Therefore, the partition walls 44 divide the space around the heater tube 41 in the axial direction within the case 40a. As a result, the partition walls 44 form a plurality of heat medium flow spaces VS in the axial direction of the heater tube 41 within the case 40a.

[0060] 5, the above-mentioned multiple steam inlets 42 are positioned corresponding to each heat transfer medium flow space VS separated by partition walls 44. That is, one steam inlet 42 is provided in the case 40a for each heat transfer medium flow space VS. The multiple steam inlets 42 introduce steam flowing through each branch pipe 14 into each heat transfer medium flow space VS.

[0061] Since adjacent heat medium flow spaces VS are separated by partition walls 44, when steam is introduced into each heat medium flow space VS from each steam inlet 42, the partition walls 44 prevent the introduced steam from spreading in the axial direction of the heater tubes 41. This increases the linearity of the steam introduced into the heat medium flow space VS in the direction along the partition walls 44 (the vertical direction in FIG. 5). As a result, heat is efficiently transferred from the steam to the heater tubes 41 for each heat medium flow space VS. In other words, the heat transfer from the steam to the heater tubes 41 is improved for each heat medium flow space VS.

[0062] (2-4. Other configurations of thermosyphons) 6 shows another configuration of the thermosiphon 1, and is an explanatory diagram of the vicinity of the connection between the thermosiphon 1 and the heater 40, as viewed from the direction of the central axis C0 of the heater 40. As shown in the figure, the thermosiphon 1 may have multiple sets of a main pipe 13 and multiple branch pipes 14 (branched from the main pipe 13) in the circumferential direction of the heater 40. In the figure, an example is shown in which three sets of a main pipe 13 and multiple branch pipes 14 connected thereto are provided in the circumferential direction, but the number of sets may be two, or four or more. The multiple main pipes 13 located in the circumferential direction are provided by branching off from the second pipe 1b, for example. The circumferential direction of the heater 40 refers to the direction around the central axis of the heater 40.

[0063] In this way, by providing a plurality of sets of the main pipe 13 and the plurality of branch pipes 14 in the circumferential direction of the heater 40, steam is injected from different positions in the circumferential direction of the heater 40. This allows the heater tube 41 inside the heater 40 to be efficiently heated, and the working gas G (see FIG. 1) flowing inside the heater tube 41 to be efficiently heated.

[0064] 6 shows a configuration in which steam is ejected from each branch pipe 14 toward the central axis C0 of the heater 40, but the direction in which steam is ejected from each branch pipe 14 is not limited to the direction toward the central axis C0 (the radial direction of the heater 40). FIG. 7 shows another configuration of the thermosiphon 1, and is an explanatory diagram of the vicinity of the connection between the thermosiphon 1 and the heater 40 as viewed from the direction of the central axis C0 of the heater 40. As shown in the figure, a configuration in which steam is ejected downward from each branch pipe 14 and supplied to the inside of the heater 40 may also be used. Even with this configuration, steam can be ejected from different circumferential positions relative to the heater 40, and the heater tube 41 inside the heater 40 can be efficiently heated.

[0065] (2-5. Inclined arrangement of heater tubes) 8 is a cross-sectional view showing another example of the arrangement of the heater tube 41. Inside the case 40a of the heater 40, the heater tube 41 may be positioned at an incline with respect to the reference plane P0. The reference plane P0 is, for example, a horizontal plane. In the example shown in the figure, the heater tube 41 is shown in a state in which it is arranged at an angle φ (°) downward from the horizontal plane. Note that the cylindrical case 40a of the heater 40 may be arranged so that the central axis is horizontal, or may be arranged at an angle φ from the reference plane P0 like the heater tube 41, or may be inclined at another angle.

[0066] When the heater tube 41 is positioned at an angle, even if droplets DP of condensed water adhere to the surface of the heater tube 41 inside the case 40a, the adhered droplets DP move downward along the outer circumferential surface of the heater tube 41. This further reduces the retention of condensed water on the surface of the heater tube 41. This is expected to reliably improve the heat transfer from steam to the heater tube 41.

[0067] (2-6. Positional relationship between the condensate drain and the second connection part) 9 is an explanatory diagram showing a schematic diagram of the connection relationship between the main body 30 of the engine section 20 and the thermosiphon 1. As described above, the first pipe 1a is located in the flow path FP of the heat source HS, and the condensed water in the heater 40 is discharged from the condensed water discharge port 43 and then returned to the first pipe 1a through the third pipe 1c (including the condensed water pipe 16 and the communicating pipe 15). Therefore, the third pipe 1c constitutes a condensed water introduction pipe that guides the condensed water discharged from the condensed water discharge port 43 of the heater 40 into (the first pipe 1a of) the flow path FP of the heat source HS.

[0068] At this time, it is desirable that the second connection part 12 is located below the condensed water discharge port 43. In other words, it is desirable that the connection part (second connection part 12) of the third piping 1c with the flow path FP of the heat source HS is located below the condensed water discharge port 43. Note that, as long as the above positional relationship is realized, the third piping 1c may have a horizontal part midway along the piping, as shown in FIG.

[0069] When the second connection part 12 and the condensed water discharge port 43 are in the above-mentioned positional relationship, the direction in which the condensed water flows from the condensed water discharge port 43 to the second connection part 12 in the third pipe 1c can be easily set to a direction from the upper side to the lower side, that is, a natural direction in which the condensed water flows without resisting the direction of gravity. This further improves the drainage of the condensed water from the heater 40.

[0070] <3. Supplementary Information> In this embodiment, as shown in FIG. 1, the expansion piston EP and the heater 40 are arranged in a straight line in the movement direction of the expansion piston EP in the main body 30. In addition, the cooler 50 and the compression piston CP are arranged in a straight line in the movement direction of the compression piston CP in the main body 30. The movement direction of the expansion piston EP refers to the direction in which the expansion piston EP reciprocates in the main body 30 due to the expansion of the working gas G in the main body 30 and the rotation of the expansion side crankshaft 84. On the other hand, the movement direction of the compression piston CP refers to the direction in which the compression piston CP reciprocates in the main body 30 due to the compression of the working gas G in the main body 30 and the rotation of the compression side crankshaft 89. In this case, the entire expansion space ES between the expansion piston EP and the heater 40 can be made to contribute to the pressing of the expansion piston EP. In addition, the entire compression space CS between the cooler 50 and the compression piston CP can be made to contribute to the retraction of the compression piston CP. Therefore, there is no void space in the expansion space ES that does not contribute to the pressing of the expansion piston EP. Moreover, in the compression space CS, there is no void space that does not contribute to the drawing in of the compression piston CP. As a result, by heating the working gas G by the heater 40 and cooling the working gas G by the cooler 50, the Stirling engine 100 (particularly the engine section 20) can be driven efficiently, and the output of the engine section 20 (specifically the rotation speed of the output shaft SH) can be increased.

[0071] Therefore, from the viewpoint of reducing the dead space and increasing the output of the engine section 20, it is desirable that the expansion piston EP and the heater 40 are arranged in a straight line within the main body 30, and that the cooler 50 and the compression piston CP are also arranged in a straight line within the main body 30.

[0072] Furthermore, if there is a bend in the flow path inside the main body 30, there is a concern that pressure loss will occur at the bend, which will result in a decrease in the output of the engine section 20. From the perspective of avoiding a decrease in the output of the engine section 20 due to the pressure loss, it is desirable to arrange the expansion piston EP, heater 40, cooler 50, and compression piston CP in a straight line inside the main body 30, as shown in FIG.

[0073] In addition, when it is more important to realize a compact layout than to prevent a reduction in the output of the engine unit 20 due to pressure loss, the main body 30 may have a curved portion. For example, when the regenerator 60 is positioned extending in one direction within the main body 30, the expansion piston EP and the heater 40 may be arranged side by side in a direction intersecting the one direction within the main body 30, and the cooler 50 and the compression piston CP may also be arranged side by side in a direction intersecting the one direction within the main body 30. In other words, the expansion piston EP and the heater 40, and the cooler 50 and the compression piston CP may be arranged side by side in parallel.

[0074] <4. Notes> The Stirling engine described in this embodiment can also be expressed as follows.

[0075] The Stirling engine in Appendix (1) is a thermosiphon containing a heat transfer medium that receives heat from a heat source; A body that contains a working gas; a heater disposed in the body and configured to apply heat to the working gas by the heat medium, The heater is at least one heater tube through which the working gas flows; a condensed water outlet for discharging condensed water condensed from the steam as the heat transfer medium supplied from the thermosiphon, The condensate drain is located below the (lowest) heater tube.

[0076] The Stirling engine of appendix (2) is the Stirling engine of appendix (1), The thermosiphon is A main pipe through which the steam as the heat transfer medium flows; a plurality of branch pipes branched from the main pipe and arranged side by side in the axial direction of the heater tube, The heater has a steam inlet port connected to the plurality of branch pipes.

[0077] The Stirling engine of appendix (3) is the Stirling engine of appendix (2), the heater further includes a partition wall having a through hole through which the heater tube passes, the partition wall divides a space around the heater tube in the axial direction to form a plurality of heat medium flow spaces in the axial direction, The plurality of steam inlets are positioned corresponding to the respective heat transfer medium flow spaces separated by the partition walls, and introduce the steam into the respective heat transfer medium flow spaces.

[0078] The Stirling engine of appendix (4) is the Stirling engine of appendix (2) or (3), The thermosiphon has a plurality of sets of the main pipe and a plurality of the branch pipes arranged in a circumferential direction of the heater.

[0079] A Stirling engine according to claim (5) is a Stirling engine according to any one of claims (1) to (4), The heater tube is positioned at an incline with respect to a reference plane.

[0080] A Stirling engine according to claim (6) is a Stirling engine according to any one of claims (1) to (5), The thermosiphon further includes a condensed water introduction pipe that introduces the condensed water discharged from the condensed water discharge port to a pipe in a flow path of the heat source, A connection portion of the condensed water introduction pipe with the flow path of the heat source is located below the condensed water discharge port.

[0081] Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and the invention can be expanded or modified without departing from the spirit of the invention. [Industrial Applicability]

[0082] The present invention can be used in a Stirling engine that utilizes heat from a heat source such as exhaust heat and performs heat exchange to drive an engine section. [Explanation of symbols]

[0083] 1 Thermosyphon 1a First pipe 1b Second piping 1c Third pipe (condensate introduction pipe) 12 Second connection part 13 Main piping 14 Branch piping 15 Communication pipe 16 Condensate piping 30 Main unit 40 Heater 41 Heater tube 42 Steam inlet 43 Condensate drain 44 Bulkhead 44a through hole 100 Stirling Engine FP flow path G Working gas HS heat source P0 reference plane VS Heat medium circulation space

Claims

1. a thermosiphon containing a heat transfer medium that receives heat from a heat source; A body that contains a working gas; a heater disposed in the body and configured to apply heat to the working gas by the heat medium, The heater is at least one heater tube through which the working gas flows; a condensed water outlet for discharging condensed water condensed from the steam as the heat transfer medium supplied from the thermosiphon, A Stirling engine, wherein the condensate drain is located below the heater tube.

2. The thermosiphon is A main pipe through which the steam as the heat transfer medium flows; a plurality of branch pipes branched from the main pipe and arranged side by side in the axial direction of the heater tube, 2. The Stirling engine according to claim 1, wherein the heater has a steam inlet port connected to a plurality of the branch pipes.

3. the heater further includes a partition wall having a through hole through which the heater tube passes, the partition wall divides a space around the heater tube in the axial direction to form a plurality of heat medium flow spaces in the axial direction, 3. The Stirling engine according to claim 2, wherein the plurality of steam inlets are positioned corresponding to the respective heat transfer medium flow spaces separated by the partition walls, and introduce the steam into the respective heat transfer medium flow spaces.

4. 3. The Stirling engine according to claim 2, wherein the thermosiphon has a plurality of sets of the main pipe and the plurality of branch pipes arranged in a circumferential direction of the heater.

5. 2. The Stirling engine according to claim 1, wherein the heater tubes are positioned at an incline with respect to a reference plane.

6. The thermosiphon further includes a condensed water introduction pipe that introduces the condensed water discharged from the condensed water discharge port to a pipe in a flow path of the heat source, 6. The Stirling engine according to claim 1, wherein a connection portion of the condensed water inlet pipe with the flow path of the heat source is positioned below the condensed water outlet.

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