CN102733991B - Stirling engine heating head for enhancing convection heat transfer by utilizing rotational flow - Google Patents

Abstract

The invention discloses a Stirling machine heating head utilizing swirling flow to enhance convective heat transfer, relates to the Stirling machine heating head technology, and is equipped with an airflow guiding device for guiding the airflow to rotate and wash the heating head tube bundle in a heating chamber. The convection heat exchange between the heat source gas and the heating head tube bundle can be enhanced, thereby improving the energy utilization rate of the gas heat source and increasing the specific power of the engine.

Description

Heating head of Stirling machine using swirling flow to enhance convective heat transfer

technical field

The invention relates to a Stirling machine heating head which utilizes swirling flow to strengthen convection heat transfer.

Background technique

Along with the increasingly serious pressure of energy crisis and environmental pollution, Stirling engine (also known as heat engine) is paid attention to again by people. The Stirling machine is an external combustion engine, which transfers the heat supplied from the outside to the closed-loop working medium inside the engine through the heating head tube bundle of the engine, and further converts it into mechanical work for power or power generation. The Stirling machine can use any form of external heat source, which overcomes the limitation that the internal combustion engine must use high-grade oil and gas energy. In addition, it has high thermal efficiency, less pollution, small vibration, low noise, simple mechanism, high reliability, and long life. Long and other advantages.

In the Stirling machine heating head with combustion flame or flue gas as the heat source, the temperature of the flame or flue gas is generally below 2000 ° C, and the particulate matter content in the flame or flue gas is usually small, the radiation ability is not strong, and the convection exchange The heat is generally much higher than the radiation heat transfer, or the convective heat transfer is equivalent to the radiation heat transfer under the condition of high temperature and high particulates (2), 1997: 150-154.]. Therefore, strengthening the convective heat exchange between the heat source gas and the heating head tube bundle is more important for improving the engine performance.

In the traditional Stirling machine that uses flue gas to provide heat, the flue gas flows directly along the radial direction of the heating head cavity, and the flue gas only passes over the inner and outer two-layer tube coils of the heating head at one time, and cannot fully contact the heater tube bundle , The turbulence of the flue gas in the heating head cavity is low, the convective heat transfer boundary layer is thick, which is not conducive to convective heat transfer, the heat energy utilization rate is low, and the specific power of the engine (the output power of the engine per unit weight) is also low. Therefore, it is necessary to invent a Stirling machine heating head capable of strengthening the convective heat transfer between the heat source gas and the heating head tube bundle, so as to recover gas waste heat more efficiently and increase the specific power of the engine at the same time.

Contents of the invention

The purpose of the present invention is to provide a Stirling engine heating head utilizing swirling flow to enhance convective heat transfer, which can make full use of gas waste heat such as internal combustion engine exhaust, industrial waste gas, and flue gas generated by fuel combustion, while increasing the specific power of the engine.

For realizing the above object, technical solution of the present invention is:

A Stirling machine heating head using swirling flow to enhance convective heat transfer, comprising a cylindrical heating head shell, a heat-resistant cylinder, a heating head tube bundle, at least one air inlet and at least one air outlet; wherein,

The proximal end of the heating head shell is fixed to the body of the Stirling machine, the air inlet is fixed to the far end surface of the heating head shell, and the air outlet is fixed to the side of the heating head shell. When working, The heat source gas is introduced from the far end of the heating head shell and drawn out from the side of the heating head shell;

The heating head tube bundle and the heat-resistant sleeve are placed inside the heating head shell. The inner wall of the heat-resistant tube surrounds the heating head tube bundle with a gap to form a heating cavity. The outer wall of the heat-resistant tube and the inner wall of the heating head shell There is a gap, the far end of the heat-resistant cylinder is fixed to the distal surface inside the housing, the proximal end of the heat-resistant cylinder is a free end, and there is a gap between the free end and the engine body;

It also includes a first airflow guiding device located near the entrance of the heating chamber and upstream of the heating head tube bundle, so that the airflow rotates in the heating chamber and scours the heating head tube bundle, which is used to enhance the convective heat exchange between the heat source gas and the heating head tube bundle, thereby Improve the energy utilization rate of the heat source gas and increase the specific power of the engine.

The Stirling machine heating head, the first airflow guiding device is an impeller comprising a plurality of blades, the blades are flat or three-dimensionally curved, the blades are fixed on the outer hub of the impeller, and the outer hub of the impeller is fixed on the on the wall of the airflow channel.

In the Stirling machine heating head, the outer hub of the impeller is detachably fixed to the wall of the airflow channel.

In the Stirling machine heating head, the orientation of the plurality of blades can be adjusted, that is, the opening of the impeller can be adjusted.

In the heating head of the Stirling machine, the vanes are detachably fixed to the outer hub of the impeller, that is, the number of vanes can be adjusted.

As for the heating head of the Stirling machine, the first airflow guiding device is a plurality of blades surrounding the centerline of the flow channel, the blades are in the shape of a plane or a three-dimensional curved surface, and the blades are directly fixed on the wall of the air flow channel.

In the Stirling machine heating head, the orientation of the blades can be adjusted.

In the Stirling machine heating head, the vanes are detachably fixed to the wall of the airflow channel, that is, the number of vanes can be adjusted.

In the Stirling machine heating head, the first airflow guiding device is a disk with a plurality of tangential slits, and the outer hub of the disk is fixed on the wall of the airflow channel.

In the Stirling machine heating head, the outer hub of the disk is detachably fixed to the wall of the air flow channel.

In the Stirling machine heating head, the first airflow guiding device is multi-tube, and each single tube in the multi-tube is fixed on the wall of the airflow channel along a tangential angle, and the heat source gas enters the airflow through the multi-tube A swirling airflow is formed behind the channel.

The Stirling machine heating head also includes a second airflow guiding device located near the outlet of the heating chamber and downstream of the heating head tube bundle, which further promotes the rotation of the airflow in the heating chamber and enhances the relationship between the heat source gas and the heating head tube bundle. convective heat transfer between them.

The Stirling machine heating head, the second airflow guiding device is a plurality of blades surrounding the centerline of the flow channel, the blades are in the shape of a plane or a three-dimensional curved surface, and the blades are directly fixed on the proximal wall of the heat-resistant cylinder .

In the Stirling machine heating head, the orientation of the blades can be adjusted.

The Stirling machine heating head is characterized in that the vanes are detachably fixed to the proximal wall of the heat-resistant cylinder, that is, the number of vanes can be adjusted.

In the heating head of the Stirling machine, the second airflow guiding device is a plurality of slits with tangential angles around the center line of the flow channel, and the plurality of slits are formed by directly slotting on the proximal wall of the heat-resistant cylinder And formed.

In the Stirling machine heating head, the second airflow guiding device is a plurality of blades surrounding the centerline of the flow channel, the blades are in the shape of a plane or a three-dimensional curved surface, and the blades are fixed to the body of the Stirling machine.

A Stirling machine heating head using swirling flow to enhance convective heat transfer, comprising a cylindrical heating head shell, a heat-resistant cylinder, a heating head tube bundle, at least one air inlet and at least one air outlet; wherein,

The proximal end of the heating head shell is fixed to the body of the Stirling machine, the air inlet is fixed to the side of the heating head shell, and the air outlet is fixed to the far end surface of the heating head shell. When working, The heat source gas is introduced from the side of the heating head shell and drawn out from the far end of the heating head shell;

The heating head tube bundle and the heat-resistant sleeve are placed inside the heating head shell. The inner wall of the heat-resistant tube surrounds the heating head tube bundle with a gap to form a heating cavity. The outer wall of the heat-resistant tube and the inner wall of the heating head shell There is a gap, the far end of the heat-resistant cylinder is fixed to the distal surface inside the housing, the proximal end of the heat-resistant cylinder is a free end, and there is a gap between the free end and the engine body;

It also includes a first airflow guiding device located near the entrance of the heating chamber and upstream of the heating head tube bundle, so that the airflow rotates in the heating chamber and scours the heating head tube bundle, which is used to enhance the convective heat exchange between the heat source gas and the heating head tube bundle, thereby Improve the energy utilization rate of the heat source gas and increase the specific power of the engine.

The Stirling machine heating head, the first airflow guiding device is a plurality of blades surrounding the centerline of the flow channel, the blades are in the shape of a plane or a three-dimensional curved surface, and the blades are directly fixed on the proximal wall of the heat-resistant cylinder , or directly affixed to the body of the Stirling machine.

In the Stirling machine heating head, the orientation of the blades can be adjusted.

The Stirling machine heating head is characterized in that the vanes are detachably fixed to the proximal wall of the heat-resistant cylinder, that is, the number of vanes can be adjusted.

In the heating head of the Stirling machine, the first airflow guiding device is a plurality of slits with tangential angles around the center line of the flow channel, and the plurality of slits are formed by directly making grooves on the proximal wall of the heat-resistant cylinder. And formed.

The Stirling machine heating head also includes a second airflow guiding device located near the outlet of the heating chamber and downstream of the heating head tube bundle, which further promotes the rotation of the airflow in the heating chamber and strengthens the gap between the heat source gas and the heating head tube bundle. convective heat transfer.

The Stirling machine heating head, the second airflow guiding device is an impeller comprising a plurality of blades, the blades are flat or three-dimensionally curved, the blades are fixed on the outer hub of the impeller, and the outer hub of the impeller is fixed on the on the wall of the airflow channel.

In the Stirling machine heating head, the outer hub of the impeller is detachably fixed to the wall of the airflow channel.

In the heating head of the Stirling machine, the orientation of the blades of the impeller can be adjusted, that is, the opening of the impeller can be adjusted.

In the heating head of the Stirling machine, the vanes are detachably fixed to the outer hub of the impeller, that is, the number of vanes can be adjusted.

In the Stirling machine heating head, the second airflow guiding device is a plurality of blades surrounding the centerline of the flow channel, the blades are in the shape of a plane or a three-dimensional curved surface, and the blades are directly fixed on the wall of the air flow channel.

In the Stirling machine heating head, the orientation of the blades can be adjusted.

The Stirling machine heating head is characterized in that the blades are detachably fixed to the wall of the airflow channel, that is, the number of blades can be adjusted.

In the Stirling machine heating head, the second airflow guiding device is a disk with a plurality of tangential slits, and the outer hub of the disk is fixed on the wall of the airflow channel.

In the Stirling machine heating head, the outer hub of the disk is detachably fixed to the wall of the air flow channel.

In the Stirling machine heating head, the second airflow guiding device is a multi-tube, and each single tube in the multi-tube is fixed on the wall of the airflow channel along a tangential angle, and the heat from the heating head tube bundle The gas leaves the heating head through multiple tubes, which further promotes the rotation of the gas in the heating chamber.

The heat source gas of the Stirling engine heating head is one of internal combustion engine exhaust gas, industrial waste gas, and flue gas produced by fuel combustion.

As for the Stirling machine heating head, ribs are provided on the outer wall of the heating head tube bundle.

As for the Stirling machine heating head, the fixing method is one of flange connection, bolt connection, welding, sintering and interference fit.

The invention discloses a Stirling engine heating head utilizing swirling flow to enhance convective heat transfer. The airflow guiding device is different from the swirler of common burners or combustion chambers, which can make full use of gas waste heat and increase the specific power of the engine.

Description of drawings

Figure 1 is a schematic diagram of the variation of the convective heat transfer and radiation heat transfer of the heating head of a typical Stirling machine heated by flue gas with the average temperature of flue gas;

Fig. 2 is a structural schematic diagram of a first embodiment of a Stirling machine heating head utilizing swirling flow to enhance convective heat transfer of the present invention; wherein:

Figure 2a is a top view of the appearance;

Figure 2b is a perspective view of the appearance;

Figure 2c is a front sectional view;

Figure 2d is a side view;

Fig. 3 is an exploded schematic view of the heating head of the present invention shown in Fig. 2;

Fig. 4 is a schematic diagram of an impeller-type airflow guiding device in the heating head of the present invention shown in Fig. 3; wherein:

Figure 4a is a top view;

Figure 4b is a perspective view of the appearance;

Figure 4c is a front sectional view;

Figure 4d is a side view;

Fig. 5 is a schematic diagram of the heat-resistant cylinder surrounding the thermal head tube bundle in the heating head of the present invention shown in Fig. 3; wherein:

Figure 5a is a cross-sectional view;

Figure 5b is a bottom view;

Fig. 6 is a schematic diagram of the heating head housing of the present invention shown in Fig. 3; wherein:

Figure 6a is a top view;

Figure 6b is a front sectional view;

Fig. 7 is a schematic diagram of the heating head tube bundle in the present invention shown in Fig. 3; wherein:

Figure 7a is a top view;

Figure 7b is a front view;

Fig. 8 is a schematic diagram of a multi-tube airflow guiding device fixed on the distal surface of the heating head shell in the heating head of the present invention shown in Fig. 3; wherein:

Figure 8a is a top view;

Figure 8b is a perspective view of the appearance;

Figure 8c is a front sectional view;

Fig. 9 is a schematic diagram of a multi-slit airflow guiding device fixed on the distal surface of the heating head shell in the heating head of the present invention shown in Fig. 3; wherein:

Figure 9a is a top view;

Figure 9b is a perspective view of the appearance;

Figure 9c is a front view;

Fig. 10 is a multi-blade airflow guiding device fixed on the proximal wall of the heat-resistant cylinder in the heating head of the present invention shown in Fig. 3; wherein:

Figure 10a is a bottom view;

Figure 10b is a perspective view of the appearance;

Fig. 11 is a schematic diagram of a multi-blade airflow guiding device fixed on the body of the Stirling machine in the heating head of the present invention shown in Fig. 3; wherein:

Figure 11a is a top view;

Figure 11b is a perspective view of the appearance;

Figure 12 is a schematic diagram of another embodiment of the heating head of the present invention; wherein:

Figure 12a is an exploded assembly view;

Figure 12b is a perspective view of the assembled appearance;

Fig. 12c is a perspective view of the appearance of the multi-blade airflow guide device fixed to the proximal wall of the heat-resistant cylinder near the entrance of the heating chamber when viewed obliquely from below.

Detailed ways

The first embodiment of the present invention will be described in detail below in conjunction with the accompanying drawings.

Figure 1 shows the variation of convective heat transfer and radiation heat transfer with the average smoke temperature of the heating head of a typical Stirling machine with flue gas as the heat source. When the average smoke temperature is 1200°C, the convective heat transfer is about 4 times that of the radiation heat transfer; and when the average smoke temperature is 400°C, the convective heat transfer is about 19 times that of the radiation heat transfer. From a simple theoretical analysis, it can be seen that enhancing convective heat transfer is of great significance for making full use of the waste heat of flue gas and improving the specific power of the machine, especially for medium and low temperature flue gas, the effect will be more obvious.

Fig. 2 and Fig. 3 are respectively an assembly view and an exploded assembly view of the Stirling machine heating head according to the first embodiment of the present invention. Figures 4-7 show various parts diagrams. The heating head consists of a heating head housing 5, a flue gas inlet 1 connected to the far end surface of the heating head housing 5, an impeller 2 made of a heat-resistant material such as ceramics, a heating head tube bundle 3, and a heating head tube bundle 3 made of a heat-resistant material such as ceramics. It consists of a heat-resistant cylinder 4 made of etc. and a flue gas outlet 6 arranged on the side of the heating head shell. The impeller 2 is the first airflow guide device in this embodiment, in which a plurality of streamlined blades are fixed on the outer hub of the impeller, and the outer hub of the impeller is fixed on the airflow channel located near the entrance of the heating chamber and upstream of the heating head tube bundle on the wall. The heat-resistant cylinder 4 is surrounded by the tube bundle 3, and its distal end is an annular plate 7 for fixing to the shell 5. The lower edge of the plate 7 and the upper edge of the tube bundle 3 maintain a gap of about 1mm, as an allowable The space for the tube bundle to expand, and to prevent the flue gas from directly short-circuiting into the outer ring of the tube bundle without passing through the inner tube bundle. The cylindrical inner wall of the heat-resistant cylinder 4 maintains a gap of about 25mm from the outer edge of the tube bundle 3, guides the flue gas to rotate and flow from one end to the other end along the axial direction of the heating head, and can play the role of reflecting radiation and keeping warm. The proximal end of the heat-resistant cylinder 4 is provided with many oblique slots 8 to form a second airflow guiding device for guiding the flue gas to flow out of the heat-resistant cylinder 4 from inside to outside and enter the housing gap 9 outside the cylinder. The design of the casing 5 and the outlet 6 should ensure that the flue gas is uniformly mixed in the casing gap 9, so that the airflow resistance and flow rate of the flue gas at all angles along the circumferential direction are roughly uniform.

The flue gas with a certain flow rate enters the heating head from the flue gas inlet 1, as shown by the arrow in the figure. After passing the impeller, the airflow is rotated. While the rotating air flows along the axial direction of the heating head, it rotates and scours the heating head tube bundle, as shown by the arrow in the figure. Convective heat exchange and radiation heat exchange occur between the flue gas and the tube bundle 3, and the heat is further transferred to the internal working medium of the Stirling machine in the tube through the tube wall, such as helium or hydrogen, and part of the heat is converted into mechanical work. The flue gas whose temperature drops after heat release rotates at the other end of the heating head through the chute 8 on the heat-resistant cylinder 4 and flows into the shell gap 9, and then is uniformly mixed in the shell gap 9 and then discharged out of the system through the flue gas outlet 6. As shown by the arrow in the figure.

The airflow guiding device in the present invention enables the swirling flue gas flow to pass through multiple rows of heating head tube bundles along the circumference of the heating head before leaving the heating head cavity. The mechanism of the enhanced convective heat transfer can be explained as follows: It can be simply understood as under the premise that the heat transfer coefficient is roughly constant, each flue gas can wash more tube bundles, that is, the convective heat transfer area is greatly increased; it can also be understood as the total convective heat transfer area (that is, the entire The outer surface area of the heating head tube bundle) remains unchanged, but the rotating airflow enhances the degree of turbulence in the heating head cavity, and the airflow turbulence helps to destroy and thin the boundary layer of convective heat transfer, thereby greatly improving the flow rate of the entire flue gas. Overall convective heat transfer coefficient.

Table 1 shows a waste heat utilization Stirling machine using exhaust gas from a gasoline engine as a heat source, when the intake temperature is 800°C, the performance comparison before and after installing the flue gas guiding impeller of the present invention.

Table 1 has and does not have the performance contrast of Stirling machine under the situation of impeller guide device of the present invention

It can be seen from the data in Table 1 that after using the impeller deflector, the temperature of the outlet flue gas dropped by 48°C, the utilization rate of flue gas heat energy increased by 32%, and the specific power of the Stirling machine increased by 26.7%; the circulation of flue gas The drag has only risen by 0.5kPa, which is perfectly acceptable.

In the above embodiments, the blades are in a streamlined three-dimensional curved shape, but they can also be designed in a flat shape that is easy to process. The orientation of the blades can also be designed to be adjustable, that is, the opening of the impeller can be adjusted, such as using a pull rod to adjust the opening of the impeller. The detachable connection between the blade and the outer hub of the impeller can also be designed, that is, the number of blades can also be designed to be adjustable. In the above embodiments, the outer hub of the impeller is detachably fixed to the wall of the air flow channel, but it can also be designed as a non-detachable fixed connection.

In the above embodiments, the first airflow guiding device is an impeller including a plurality of blades, but it can also be designed as a plurality of planar or three-dimensional curved blades around the centerline of the flow channel, and the blades are directly fixed near the entrance of the heating chamber And located on the wall of the gas flow channel upstream of the heating head tube bundle. The orientation of the vanes can be fixed or adjustable, and the vanes can be detachably or non-detachably fixedly connected to the wall of the airflow channel.

In the above-mentioned embodiment, the first airflow guiding device is an impeller comprising a plurality of blades, but it can also be designed as a disk with multiple tangential slots, such as the multi-slit airflow guiding device 11 shown in Figure 9, in a There are many slits along the tangential direction on the conical disk, and the outer hub of the disk is fixed on the wall of the airflow channel near the entrance of the heating chamber and located upstream of the heating head tube bundle, which is used to replace the impeller guide device in Figures 2, 3, and 4 2 and air inlet 1. There can be detachable or non-detachable affixation between the disc outer hub and the wall of the airflow channel. After the heat source gas flows through the multi-slit airflow guiding device 11, it forms a downwardly rotating airflow, which scours the tube bundle of the heating head, so as to achieve the purpose of enhancing heat transfer.

In the above-mentioned embodiment, the first airflow guiding device is an impeller comprising a plurality of blades, but it can also be designed in the form of multi-tubes, such as the multi-tube airflow guiding device 10 shown in Figure 8, each single tube in the multi-tube The tubes are fixed at a tangential angle on the wall of the gas flow channel near the entrance of the heating chamber and located upstream of the tube bundle of the heating head. After the heat source gas enters the airflow channel tangentially through the multi-tube airflow guide device, it forms a rotating downward airflow to scour the heating head tube bundle to achieve the purpose of enhancing heat transfer.

In the above embodiments, the second airflow guiding device is a plurality of slits with tangential angles around the centerline of the flow channel formed by directly slotting on the distal wall of the heat-resistant cylinder, but it can also be designed to surround the flow channel A plurality of planar or three-dimensional curved blades on the centerline, as shown in Figure 10, can be directly fixed on the proximal wall of the heat-resistant cylinder, and the orientation of the blades can also be designed to be adjustable. The vane may be detachably or non-detachably fixedly connected to the proximal wall of the heat-resistant cylinder.

In addition, the second airflow guiding device may not be fixed on the proximal wall of the heat-resistant cylinder, but fixed on the body of the Stirling machine near the outlet of the heating chamber and located downstream of the heating head tube bundle, designed to surround the center of the flow channel A plurality of planar or three-dimensional curved blades of the line, as shown in FIG. 11 .

The present invention can also take another embodiment, the difference from the above embodiment is that one or more air inlets are affixed to the side of the heating head housing, and one or more air outlets are affixed to the heating head housing on the distal face. For example, in the layout shown in FIG. 12 , the multi-blade airflow guiding device 12 is fixed to the proximal end wall of the heat-resistant cylinder near the entrance of the heating chamber and upstream of the heating head tube bundle. The heat source gas is introduced from the side of the heating head shell, and after being guided by the multi-blade airflow guide device 12, it rotates and scours the heating head tube bundle in the heating chamber to achieve the purpose of enhancing heat transfer, and then passes through the outlet near the heating chamber and located at the The impeller guide 2 downstream of the heating head tube bundle rotates up and out of the heating head. In the case of this embodiment, the first airflow guiding device located near the entrance of the heating chamber and upstream of the heating head tube bundle can be a plurality of planar or three-dimensional curved blades around the centerline of the flow channel, and the blades are directly fixed on the The near-end wall of the heat-resistant cylinder can also be fixed to the body of the Stirling machine near the outlet of the heating chamber and located downstream of the heating head tube bundle; it can also be a plurality of slits with tangential angles around the centerline of the flow channel, The plurality of slits are formed by slotting directly into the proximal wall of the heat-resistant cylinder. In the case of this embodiment, a second airflow guiding device located close to the outlet of the heating chamber and downstream of the tube bundle of the heating head may also be included. The second airflow guiding device can be an impeller including a plurality of blades, or a plurality of planar or three-dimensional curved blades directly fixed on the wall of the airflow channel around the centerline of the flow channel; The outer hub of the disk is fixed on the wall of the airflow channel; it can also be in the form of multiple tubes, and each single tube in the multiple tubes is fixed on the wall of the airflow channel along a tangential angle.

As for the above-mentioned Stirling engine heating head, the heat source gas can be internal combustion engine exhaust gas, industrial waste gas, flue gas produced by fuel combustion, and the like.

As for the Stirling machine heating head mentioned above, the fixing method can be flange connection, bolt connection, welding, sintering, interference fit and other methods.

In the above embodiments, the fins installed on the outer surface of the tube bundle are not shown. In practice, it can be determined whether to add fins to the outer wall of the tube bundle of the heating head according to the convective heat transfer and flow resistance conditions.

Claims (34)

1. A Stirling engine heating head for strengthening convective heat transfer by utilizing rotational flow comprises a cylindrical heating head shell, a heat-resistant cylinder, a heating head tube bundle, at least one air inlet and at least one air outlet; it is characterized in that the preparation method is characterized in that,

the near end of the heating head shell is fixedly connected to the Stirling engine body, the air inlet is fixedly connected to the far end face of the heating head shell, the air outlet is fixedly connected to the side face of the heating head shell, and when the Stirling engine works, heat source gas is introduced from the far end of the heating head shell and is led out from the side face of the heating head shell;

the heating head tube bundle and the heat-resistant barrel are sleeved in the heating head shell, the inner side wall of the heat-resistant barrel surrounds the heating head tube bundle by a gap to form a heating cavity, the outer side wall of the heat-resistant barrel has a gap with the inner wall of the heating head shell, the far end of the heat-resistant barrel is fixedly connected to the far end surface in the shell, the near end of the heat-resistant barrel is a free end, and the free end has a gap with the engine body;

the first airflow guiding device is positioned close to the inlet of the heating cavity and at the upstream of the heating head tube bundle, so that airflow rotationally washes the heating head tube bundle in the heating cavity and is used for enhancing the heat convection between the heat source gas and the heating head tube bundle, thereby improving the energy utilization rate of the heat source gas and improving the specific power of an engine;

the second air flow guiding device is positioned close to the outlet of the heating cavity and is positioned at the downstream of the heating head tube bundle, so that the air flow is further promoted to rotate in the heating cavity, and the heat convection between the heat source gas and the heating head tube bundle is enhanced.

2. A stirling machine heater head according to claim 1, wherein the first airflow directing means is an impeller comprising a plurality of blades, the blades being planar or curved in three dimensions, the blades being secured to an impeller outer hub which is secured to the airflow passage wall.

3. A stirling machine heater head according to claim 2, wherein the impeller outer hub is removably secured to the wall of the gas flow passage.

4. A stirling machine heater head according to claim 2, wherein the orientation of the plurality of vanes is adjustable, i.e. the impeller opening is adjustable.

5. A stirling machine heater head according to claim 2, wherein the vanes are removably secured to the outer hub of the impeller, i.e. the number of vanes is adjustable.

6. A stirling machine heater head according to claim 1, wherein the first airflow directing means is a plurality of vanes about the centre line of the flow passage, the vanes being planar or curved in three dimensions, the vanes being directly attached to the walls of the airflow passage.

7. A Stirling engine heating head according to claim 6, wherein the orientation of the plurality of vanes is adjustable.

8. A Stirling machine heater head according to claim 6, wherein the vanes are removably secured to the wall of the gas flow passage, i.e. the number of vanes is adjustable.

9. A stirling machine heater head according to claim 1, wherein the first airflow directing means is a disc having a plurality of tangential slits, the outer hub of the disc being secured to the wall of the airflow passage.

10. A stirling machine heater head according to claim 9, wherein the outer disk hub is removably secured to the wall of the gas flow passage.

11. A stirling machine heater head according to claim 1, wherein the first airflow directing means is a plurality of tubes, each individual tube of the plurality of tubes being attached to the wall of the airflow channel at a tangential angle, the heat source gas entering the airflow channel through the plurality of tubes forming a rotating airflow.

12. A stirling machine heater head according to claim 1, wherein the second flow directing means are a plurality of vanes about the centre line of the flow path, the vanes being planar or curved in three dimensions and being attached directly to the heat resistant cylinder proximal end wall.

13. A stirling machine heater head according to claim 12, wherein the orientation of the plurality of vanes is adjustable.

14. A stirling machine heater head according to claim 12, wherein the vanes are removably secured to the proximal wall of the heat resistant cylinder, i.e. the number of vanes is adjustable.

15. A stirling machine heater head according to claim 1, wherein the second air flow guide is a plurality of tangentially angled slots around the centre line of the flow passage, the slots being formed by slotting directly in the proximal wall of the heat resistant cylinder.

16. A stirling machine heater head according to claim 1, wherein the second flow directing means is a plurality of vanes about the centre line of the flow passage, the vanes being planar or curved in three dimensions, the vanes being affixed to the stirling machine body.

17. A Stirling engine heating head for strengthening convective heat transfer by utilizing rotational flow comprises a cylindrical heating head shell, a heat-resistant cylinder, a heating head tube bundle, at least one air inlet and at least one air outlet; it is characterized in that the preparation method is characterized in that,

the near end of the heating head shell is fixedly connected to the Stirling engine body, the air inlet is fixedly connected to the side face of the heating head shell, the air outlet is fixedly connected to the far end face of the heating head shell, and when the Stirling engine works, heat source gas is introduced from the side face of the heating head shell and is led out from the far end of the heating head shell;

the heating head tube bundle and the heat-resistant barrel are sleeved in the heating head shell, the inner side wall of the heat-resistant barrel surrounds the heating head tube bundle by a gap to form a heating cavity, the outer side wall of the heat-resistant barrel has a gap with the inner wall of the heating head shell, the far end of the heat-resistant barrel is fixedly connected to the far end surface in the shell, the near end of the heat-resistant barrel is a free end, and the free end has a gap with the engine body;

the first airflow guiding device is positioned close to the inlet of the heating cavity and at the upstream of the heating head tube bundle, so that airflow rotationally washes the heating head tube bundle in the heating cavity and is used for enhancing the heat convection between the heat source gas and the heating head tube bundle, thereby improving the energy utilization rate of the heat source gas and improving the specific power of an engine;

the second air flow guiding device is positioned close to the outlet of the heating cavity and is positioned at the downstream of the heating head tube bundle, so that the air flow is further promoted to rotate in the heating cavity, and the heat convection between the heat source gas and the heating head tube bundle is enhanced.

18. A stirling machine heater head according to claim 17, wherein the first airflow directing means is a plurality of vanes about the centre line of the flow path, the vanes being planar or curved in three dimensions and being secured directly to the heat resistant cylinder proximal end wall or directly to the stirling machine body.

19. A stirling machine heater head according to claim 18, wherein the orientation of the plurality of vanes is adjustable.

20. A stirling machine heater head according to claim 18, wherein the vanes are removably secured to the proximal wall of the heat resistant cylinder, i.e. the number of vanes is adjustable.

21. A stirling machine heater head according to claim 17, wherein the first airflow directing means is a plurality of tangentially angled slots around the centre line of the flow path, the plurality of slots being formed by slotting directly in the proximal end wall of the heat resistant cylinder.

22. A stirling machine heater head according to claim 17, wherein the second gas flow directing means is an impeller comprising a plurality of blades, the blades being planar or curved in three dimensions, the blades being secured to an impeller outer hub which is secured to the wall of the gas flow passage.

23. A stirling machine heater head according to claim 22, wherein the impeller outer hub is removably secured to the wall of the gas flow passage.

24. A stirling machine heater head according to claim 22, wherein the vanes of the impeller are adjustable in orientation, i.e. impeller opening.

25. A stirling machine heater head according to claim 22, wherein the vanes are removably secured to the outer hub of the impeller, i.e. the number of vanes is adjustable.

26. A stirling machine heater head according to claim 17, wherein the second flow directing means is a plurality of vanes about the centre line of the flow path, the vanes being planar or curved in three dimensions and the vanes being secured directly to the walls of the flow path.

27. A stirling machine heater head according to claim 26, wherein the orientation of the plurality of vanes is adjustable.

28. A stirling machine heater head according to claim 26, wherein the vanes are removably secured to the wall of the gas flow passage, i.e. the number of vanes is adjustable.

29. A stirling machine heater head according to claim 17, wherein the second flow guide is a disc having a plurality of tangential slits, an outer hub of the disc being secured to the wall of the flow passage.

30. A stirling machine heater head according to claim 29, wherein the outer disk hub is removably secured to the wall of the gas flow passage.

31. A stirling machine heater head according to claim 17, wherein the second gas flow guide is a manifold, each individual tube of the plurality of tubes being affixed to the wall of the gas flow passage at a tangential angle, the gas from the heater head bundle exiting the heater head through the plurality of tubes further facilitating rotation of the gas in the heating chamber.

32. A stirling machine heater head according to claim 1 or 17, wherein the heat source gas is one of exhaust gas from an internal combustion engine, industrial waste gas, flue gas from the combustion of fuel.

33. A stirling machine heater head according to claim 1 or claim 17, wherein the heater head tube bundle is ribbed on its outer wall.

34. A stirling machine heater head according to claim 1 or claim 17, wherein the fastening means is one of a flange connection, a bolted connection, a welded connection, a sintered connection, an interference fit.