Tubular heater and vehicle
By setting a buffer chamber in the tube heater to allow the fluid to flow radially across the outer surface of the heating member, the problem of uneven heating caused by changes in the fluid flow is solved, and uniform heating of the fluid is achieved.
Patent Information
- Application Number
- CN202422242539.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2034-09-12
AI Technical Summary
When the fluid flow rate is small, the contact area between the fluid and the heating pipe is small, resulting in uneven heating.
A tube heater is designed, including a housing and a heating member, and the housing is provided with an inlet channel, an outlet channel and a connecting buffer chamber. When the fluid enters the heating passage through the buffer chamber, it flows radially and covers the outer surface of the heating member to ensure that the fluid is evenly in contact with the heating member.
The contact area between the fluid and the heating element is increased, uniform heating of the fluid is achieved, and the impact of flow rate changes on heating uniformity is solved.
Smart Images
Figure CN223064057U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of heaters, in particular to a tubular heater and a vehicle. Background Art
[0002] A heater is a crucial component in the thermal management system of new energy vehicles or energy storage systems. It can provide heat for the battery pack, preheat the engine, heat the interior of the vehicle, heat the coolant, etc., so as to ensure the normal operation of various systems of the vehicle in low-temperature environments or other environments. As a type of heater, the working principle of a tubular heater is usually that a fluid flows through its interior, the fluid contacts the internal heating tube, the heating tube heats the fluid, and then the heated fluid provides necessary heat for the engine or other systems.
[0003] In the process of implementing the present utility model, the inventor of the present utility model found that: when the flow rate of the fluid is small, the fluid often only flows through the lower side of the heating tube, resulting in a small contact area between the fluid and the heating tube, and thus uneven heating of the fluid. Summary of the Utility Model
[0004] In view of the above problems, the embodiments of the present utility model provide a tubular heater and a vehicle, which overcome the above problems or at least partially solve the above problems.
[0005] According to one aspect of the present utility model, there is provided a tubular heater, including a housing provided with a heating channel, an inlet channel and an outlet channel communicating with the heating channel. The inlet channel is located at one end of the housing, the outlet channel is located at the other end of the housing, the heating channel is axially parallel to the inlet channel and the outlet channel, the heating channel is located between the inlet channel and the outlet channel, and a buffer cavity is further provided on the housing. The buffer cavity communicates with the inlet channel and the heating channel, the buffer cavity is located between the inlet channel and the heating channel, and the bottom of the buffer cavity is tangentially arranged radially with the inner side wall of the heating channel; a heating element, at least part of the heating element is installed in the heating channel, and the heating element is coaxially arranged with the heating channel; wherein, an external fluid enters the buffer cavity from the inlet channel, and flows into the heating channel along the radial direction through the bottom of the buffer cavity. The fluid rotates along the radial direction and at least partially wraps the outer surface of the heating element until it flows out from the outlet channel.
[0006] In an optional manner, the inlet channel and the outlet channel are coaxially arranged.
[0007] In an optional manner, there are multiple heating channels, and the multiple heating channels are arranged axially parallel to each other; there are multiple heating elements, and the number of heating elements corresponds to the number of heating channels, and one heating element is installed in one heating channel.
[0008] In an optional manner, a plurality of guide plates are provided on the shell, the plurality of guide plates are located in the buffer cavity, each of the guide plates is arranged between the liquid inlets of adjacent heating channels, the plurality of guide plates divide the buffer cavity into a plurality of guide channels, and one guide channel is connected to one heating channel.
[0009] In an optional manner, a manifold is further provided on the shell, the manifold connects the outlet channel and the heating channel, and the manifold is located between the outlet channel and the heating channel.
[0010] In an optional manner, the shell includes an inlet end, a heating end and an outlet end, one end of the heating end is detachably connected to the inlet end, the other end of the heating end is detachably connected to the outlet end, the inlet channel is located on the inlet end, the outlet channel is located on the outlet end, and the heating channel and the buffer chamber are located on the heating end.
[0011] In an optional manner, a sealing groove and a mounting hole penetrating the bottom of the sealing groove are further provided on the inlet end, and the mounting hole is connected to the heating channel; the heating element and the shell are detachably connected, a sealing ring is provided on the outer periphery of one end of the heating element, and the other end of the heating element is installed in the heating channel through the mounting hole, and one side of the sealing ring abuts against the bottom of the sealing groove.
[0012] In an optional manner, the shell further includes a pressure plate, which is detachably connected to a side of the inlet end facing away from the heating end, and the pressure plate abuts against the other side of the sealing ring.
[0013] In an optional manner, a accommodating cavity is provided on the pressure plate, the accommodating cavity is communicated with the sealing groove, and part of the heating element is located in the accommodating cavity; a shielding plate is also provided on the shell, the shielding plate cover is arranged at the cavity opening of the accommodating cavity, and the shielding plate is detachably connected to the pressure plate.
[0014] In an alternative embodiment, a control cavity and an opening communicating with the control cavity are provided on the upper side wall of the heating end; the housing further includes a sealing plate and a wire outlet gasket. The wire outlet gasket is disposed on the sealing plate, the sealing plate covers the opening, and the wire outlet hole on the wire outlet gasket communicates with the control cavity; the housing further includes a first upper cover plate that covers the sealing plate and is attached to the upper side wall of the heating end. The first upper cover plate is provided with a first wire groove that communicates with the wire outlet hole on the wire outlet gasket; a second wire groove communicating with the accommodation cavity is further provided on the pressing plate, and the second wire groove communicates with the first wire groove.
[0015] According to another aspect of the present invention, a vehicle is provided, including the tubular heater as described above.
[0016] The beneficial effects of the embodiments of the present invention are as follows: Different from the prior art, the embodiments of the present invention are provided with a housing and a heating element. Among them, the housing is provided with a heating channel, an inlet channel and an outlet channel communicating with the heating channel. The inlet channel is located at one end of the housing, and the outlet channel is located at the other end of the housing. The heating channel is arranged axially parallel to the inlet channel and the outlet channel, and the heating channel is located between the inlet channel and the outlet channel. A buffer cavity is further provided on the housing, and the buffer cavity communicates with the inlet channel and the heating channel. The buffer cavity is located between the inlet channel and the heating channel, and the bottom of the buffer cavity is tangentially arranged radially with the inner side wall of the heating channel. At least part of the heating element is installed in the heating channel, and the heating element is coaxially arranged with the heating channel. The external fluid enters the buffer cavity from the inlet channel and flows into the heating channel along the radial direction through the bottom of the buffer cavity. The fluid rotates radially and at least partially wraps the outer surface of the heating element until it flows out from the outlet channel. With such a setting, since the fluid flows into the heating channel from the buffer cavity, it rotates radially and at least partially wraps the outer surface of the heating element when flowing in, and is not limited by the amount of fluid flow. The fluid can flow while wrapping the outer surface of the heating element, which can increase the contact area between the fluid and the heating element, and thus ensure that the heating element can uniformly heat the fluid. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.
[0018] Figure 1 It is a partial structural assembly diagram of the tubular heater according to the embodiment of the present invention;
[0019] Figure 2It is a schematic diagram of the partial structure of the tubular heater according to an embodiment of the present utility model from an angle;
[0020] Figure 3 It is a schematic diagram of the partial structure of the housing of the tubular heater according to an embodiment of the present utility model;
[0021] Figure 4 It is a side sectional view of the partial structure of the tubular heater according to an embodiment of the present utility model;
[0022] Figure 5 It is a schematic diagram of the partial structure of another embodiment of the tubular heater of the present utility model;
[0023] Figure 6 It is another schematic diagram of the partial structure of the tubular heater according to an embodiment of the present utility model from another angle
[0024] Figure 7 It is another schematic diagram of the partial structure of the tubular heater according to an embodiment of the present utility model from one angle;
[0025] Figure 8 It is another schematic diagram of the partial structure of the tubular heater according to an embodiment of the present utility model from another angle. Detailed implementation manners
[0026] For the convenience of understanding the present utility model, the present utility model will be described in more detail below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is expressed as "fixed to" another element, it can be directly on the other element, or there can be one or more intermediate elements therebetween. When an element is expressed as "connected to" another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are only for the purpose of illustration.
[0027] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present utility model belongs. The terms used in this specification in the description of the present utility model are only for the purpose of describing specific embodiments and are not used to limit the present utility model. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.
[0028] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0029] Please refer to Figures 1 to 2, the tubular heater 1000 includes a housing 10 and a heating element 20. The heating element 20 is disposed within the housing 10, and fluid can flow through the interior of the housing 10 and exit after being heated by the heating element 20. The following provides a specific description of the housing 10 and the heating element 20.
[0030] For the above-mentioned housing 10 and heating element 20, as Figures 1 to 3 shown, the housing 10 includes an inlet end 101, a heating end 102, and an outlet end 103. One end of the heating end 102 is detachably connected to the inlet end 101, and the other end of the heating end 102 is detachably connected to the outlet end 103. The heating element 20 is disposed inside the heating end 102. Among them, an inlet pipe 1011 and an inlet channel 101a are provided on the inlet end 101. The inlet channel 101a is located on the inlet pipe 1011. An outlet pipe 1031 and an outlet channel 103a are provided on the outlet end 103. The outlet channel 103a is located on the outlet pipe 1031. A heating channel 102a is provided on the heating end 102. The heating channel 102a communicates with the inlet channel 101a and the outlet channel 103a. The heating channel 102a is located between the inlet channel 101a and the outlet channel 103a. External fluid enters from the inlet channel 101a, flows through the heating channel 102a, and exits until the outlet channel 103a. Among them, the inlet channel 101a is located at one end of the housing 10, the outlet channel 103a is located at the other end of the housing 10, the heating channel 102a is arranged axially parallel to the inlet channel 101a and the outlet channel 103a. At least a part of the heating element 20 is installed in the heating channel 102a. The heating element 20 and the heating channel 102a are coaxially arranged. The heating element 20 can heat the fluid flowing through the heating channel 102a. Optionally, the inlet channel 101a and the outlet channel 103a are coaxially arranged, and the inlet and outlet of the heater are on the same axis. Such a setting is beneficial to saving the space occupied by the heater and facilitating integration into the pipeline system.
[0031] In some embodiments, please also refer to Figure 4, a buffer chamber 102b is further provided on the housing 10. The buffer chamber 102b communicates with the inlet passage 101a and the heating passage 102a. The buffer chamber 102b is located between the inlet passage 101a and the heating passage 102a, and the bottom of the buffer chamber 102b is tangentially arranged radially with the inner side wall of the heating passage 102a. The external fluid enters the buffer chamber 102b from the inlet passage 101a and flows into the heating passage 102a radially along the bottom of the buffer chamber 102b. The fluid rotates radially and at least partially wraps the outer surface of the heating element 20 until it flows out from the outlet passage 103a. With this setting, since the fluid flows into the heating passage 102a from the buffer chamber 102b, it rotates radially and at least partially wraps the outer surface of the heating element 20 when flowing in, and is not limited by the amount of fluid flow. The fluid can flow while wrapping the outer surface of the heating element 20, which can increase the contact area between the fluid and the heating element 20, and further ensure that the heating element 20 can uniformly heat the fluid. Optionally, the buffer chamber 102b is located on the heating end 102.
[0032] In some embodiments, please refer to Figure 5 , the number of the heating passages 102a is multiple, and the multiple heating passages 102a are arranged parallel to each other axially. The number of the heating elements 20 is multiple, and the number of the heating elements 20 corresponds to the number of the heating passages 102a, and one of the heating elements 20 is installed in one of the heating passages 102a. It can be understood that: in this application, the number of the heating passages 102a and the heating elements 20 is not specifically limited to improve the heat output of the heater, and the user can set it according to actual needs. For example: the number of both the heating passages 102a and the heating elements 20 is 3, 4, 5, etc.
[0033] In some embodiments, a plurality of flow guiding plates 1021 are provided on the housing 10. The plurality of flow guiding plates 1021 are located in the buffer chamber 102b. Each of the flow guiding plates 1021 is arranged between the liquid inlets of adjacent heating passages 102a. The plurality of flow guiding plates 1021 divide the buffer chamber 102b into a plurality of flow guiding channels (not labeled). One flow guiding channel communicates with one of the heating passages 102a. The fluid flowing into the buffer chamber 102b from the inlet passage 101a, under the action of the plurality of flow guiding plates 1021, flows through different flow guiding channels and into different heating passages 102a respectively. It can be understood that: the flow guiding plates 1021 and the housing 10 are detachably connected or integrally formed, and this application does not specifically limit it.
[0034] In some embodiments, please refer to Figure 6The housing 10 is also provided with a manifold 102c, which is connected to the outlet channel 103a and the heating channel 102a. The manifold 102c is located between the outlet channel 103a and the heating channel 102a. The fluid flowing through the heating channel 102a converges into the manifold 102c, and then flows from the manifold 102c to the outlet channel 103a and flows out from the outlet channel 103a. Optionally, the manifold 102c is located on the outlet end 103. It can be understood that the fluid in the manifold 102c can be the fluid flowing out of one or more heating channels 102a, which is not specifically limited in the present application.
[0035] In some embodiments, the heating element 20 is detachably connected to the housing 10. To facilitate the installation of the heating element 20, a sealing groove 101b and a mounting hole 101c penetrating the bottom of the sealing groove 101b are provided on the inlet end 101. The mounting hole 101c is connected to the heating channel 102a. A sealing ring 201 is provided on the outer periphery of one end of the heating element 20. The other end of the heating element 20 is installed in the heating channel 102a from the mounting hole 101c. One side of the sealing ring 201 abuts against the bottom of the sealing groove 101b, thereby realizing the installation of the heating element 20 on the housing 10. It can be understood that the detachable connection between the heating element 20 and the housing 10 can be a screw connection, a clamp connection, a flange connection, a spiral connection, a buckle connection, etc. Among them, the sealing ring 201 can play a sealing role in the connection between the heating element 20 and the housing 10.
[0036] In some embodiments, in order to make the heating element 20 more stably limited on the shell 10, the shell 10 also includes a pressure plate 104, which is detachably connected to the side of the inlet end 101 away from the heating end 102, and the pressure plate 104 abuts against the other side of the sealing ring 201. The sealing ring 201 connected to the heating element 20 is pressed and limited by the pressure plate 104, thereby achieving the goal of stably limiting the heating element 20 on the shell 10.
[0037] In some embodiments, a receiving cavity 104a is provided on the pressing plate 104, and the receiving cavity 104a is connected to the sealing groove 101b. Part of the heating element 20 is located in the receiving cavity 104a. The receiving cavity 104a can be used to place the connecting wire of the heating element 20, and the connecting wire can be a high or low voltage wire.
[0038] In some embodiments, a shielding plate 1041 is further provided on the shell 10, and the shielding plate 1041 covers the cavity opening of the accommodating cavity 104a, and the shielding plate 1041 is detachably connected to the pressure plate 104. The shielding plate 1041 can shield and protect the connecting wires of the heating element 20, thereby reducing the entry of external rainwater into the accommodating cavity 104a.
[0039] In some embodiments, please refer to Figure 7 and Figure 8, a control cavity 102d and an opening (not labeled) communicating with the control cavity 102d are provided on the upper side wall of the heating end 102. Modules such as the control module and temperature control switch of the heater can be placed in the control cavity 102d through the opening.
[0040] In some embodiments, to achieve the shielding and sealing protection of the control cavity 102d, the housing 10 further includes a sealing plate 1022 and a wire outlet gasket 1023. The wire outlet gasket 1023 is arranged on the sealing plate 1022. The sealing plate 1022 covers the opening of the control cavity 102d. The wire outlet hole on the wire outlet gasket 1023 communicates with the control cavity 102d. The external wiring of the control module or other modules located in the control cavity 102d can extend out through the wire outlet hole on the wire outlet gasket and connect to other components on the heater, such as the connecting wire of the heating element 20. It should be noted that: to ensure the sealing performance of the control cavity 102d, the connection method between the sealing plate 1022 and the heating end 102 can be glue encapsulation, etc.
[0041] In some embodiments, the housing 10 further includes a first upper cover plate 105. The first upper cover plate 105 covers the sealing plate 1022 and is attached to the upper side wall of the heating end 102. The first upper cover plate 105 is provided with a first wire groove 1051. The first wire groove 1051 communicates with the wire outlet hole on the wire outlet gasket 1023. The pressing plate 104 is further provided with a second wire groove 1042 communicating with the accommodating cavity 104a, and the second wire groove 1042 communicates with the first wire groove 1051. The external wiring of the control module or other modules in the control cavity 102d can extend out through the wire outlet hole on the wire outlet gasket 1023 and pass through the first wire groove 1051 and the second wire groove 1042 to connect to the connecting wire located on the pressing plate 104, thereby realizing the electrical connection between the control module or other modules and the heating element 20. The settings of the first wire groove 1051 and the second wire groove 1042 can prevent the connecting wire from being directly exposed on the outer surface of the housing 10. While improving the aesthetics, it can also shield and protect the connecting wire, reduce the contact between the connecting wire and external rainwater, and reduce the occurrence of short circuits in the heating element 20. It can be understood that: to increase the sealing of the first wire groove 1051 and the second wire groove 1042 and reduce the entry of external air or rainwater into the first wire groove 1051 and the second wire groove 1042, the first wire groove 1051 and the second wire groove 1042 can be sealed by a rubber sealing ring 201.
[0042] In some embodiments, the housing 10 further includes a second lower cover plate 106. The second lower cover plate 106 is attached to the lower side wall of the heating end 102. The settings of the second lower cover plate 106 and the first upper cover plate 105 can make the shape of the housing 10 basically cylindrical. The first upper cover plate 105 and the second lower cover plate 106 can improve the external aesthetics of the housing 10 and also enhance the stiffness of the housing 10, reducing the collision damage of the housing 10.
[0043] In an embodiment of the present utility model, a housing 10 and a heating element 20 are provided. Among them, the housing 10 is provided with a heating channel 102a, an inlet channel 101a communicating with the heating channel 102a, and an outlet channel 103a. The inlet channel 101a is located at one end of the housing 10, and the outlet channel 103a is located at the other end of the housing 10. The heating channel 102a is arranged axially parallel to the inlet channel 101a and the outlet channel 103a. A buffer cavity 102b is also provided on the housing 10. The buffer cavity 102b communicates with the inlet channel 101a and the heating channel 102a. The buffer cavity 102b is located between the inlet channel 101a and the heating channel 102a. The bottom of the buffer cavity 102b is tangentially arranged with the inner side wall of the heating channel 102a, and the bottom of the buffer cavity 102b is radially tangentially arranged with the inner side wall of the heating channel 102a. At least a part of the heating element 20 is installed in the heating channel 102a. The heating element 20 is coaxially arranged with the heating channel 102a. The external fluid enters the buffer cavity 102b from the inlet channel 101a, and flows into the heating channel 102a along the radial direction through the bottom of the buffer cavity 102b. The fluid rotates along the radial direction and at least partially wraps the outer surface of the heating element 20 until it flows out from the outlet channel 103a. With such a setting, since when the fluid flows from the buffer cavity 102b into the heating channel 102a, it rotates along the radial direction and flows in at least partially wrapping the outer surface of the heating element 20, regardless of the amount of fluid flow, the fluid can wrap the outer surface of the heating element 20 and flow. In this way, the contact area between the fluid and the heating element 20 can be increased, thereby ensuring that the heating element 20 can uniformly heat the fluid.
[0044] The present utility model also provides an embodiment of a vehicle. The vehicle includes the tubular heater 1000 as described above. The functions and structures of the tubular heater 1000 can be referred to the above embodiments, and will not be elaborated here one by one.
[0045] The above are only the embodiments of the present utility model, and do not limit the patent scope of the present utility model accordingly. All equivalent structural or equivalent process transformations made by using the content of the specification and drawings of the present utility model, or directly or indirectly applied in other related technical fields, are similarly included in the patent protection scope of the present utility model.
Claims
1. A tubular heater, characterized in that, Comprising: A housing, provided with a heating channel, an inlet channel and an outlet channel communicating with the heating channel. The inlet channel is located at one end of the housing, the outlet channel is located at the other end of the housing, the heating channel is arranged axially parallel to the inlet channel and the outlet channel, the heating channel is located between the inlet channel and the outlet channel, a buffer cavity is further provided on the housing, the buffer cavity communicates with the inlet channel and the heating channel, the buffer cavity is located between the inlet channel and the heating channel, and the bottom of the buffer cavity is tangentially arranged radially with the inner side wall of the heating channel; A heating element, at least part of which is installed in the heating channel, and the heating element is coaxially arranged with the heating channel; Wherein, the external fluid enters the buffer cavity from the inlet channel, and flows into the heating channel along the radial direction through the bottom of the buffer cavity. The fluid rotates along the radial direction and at least partially wraps the outer surface of the heating element until it flows out from the outlet channel.
2. The tubular heater according to claim 1, wherein The inlet channel and the outlet channel are coaxially arranged.
3. The tubular heater according to claim 1, wherein The number of the heating channels is multiple, and the multiple heating channels are arranged axially parallel to each other; The number of the heating elements is multiple, the number of the heating elements corresponds to the number of the heating channels, and one heating element is installed in one heating channel.
4. The tubular heater according to claim 3, wherein A plurality of flow guiding plates are provided on the housing, the plurality of flow guiding plates are located in the buffer cavity, each flow guiding plate is arranged between the liquid inlet openings of adjacent heating channels, and the plurality of flow guiding plates divide the buffer cavity into a plurality of flow guiding channels, and one flow guiding channel communicates with one heating channel.
5. The tubular heater according to claim 1, wherein A collecting cavity is further provided on the housing, the collecting cavity communicates with the outlet channel and the heating channel, and the collecting cavity is located between the outlet channel and the heating channel.
6. The tubular heater according to claim 1, wherein The housing includes an inlet end, a heating end and an outlet end. One end of the heating end is detachably connected to the inlet end, the other end of the heating end is detachably connected to the outlet end, the inlet channel is located on the inlet end, the outlet channel is located on the outlet end, and the heating channel and the buffer cavity are located on the heating end.
7. The tubular heater according to claim 6, wherein A sealing groove and an installation hole penetrating through the bottom of the sealing groove are further provided on the inlet end, and the installation hole communicates with the heating channel; The heating element is detachably connected to the housing. A sealing ring is provided on the outer periphery of one end of the heating element, and the other end of the heating element is installed in the heating channel from the installation hole, and one side of the sealing ring abuts against the bottom of the sealing groove.
8. The tubular heater according to claim 7, wherein The shell further comprises a pressing plate, which is detachably connected to a side of the inlet end facing away from the heating end, and the pressing plate abuts against the other side of the sealing ring.
9. The tubular heater according to claim 8, characterized in that The pressing plate is provided with an accommodating cavity, the accommodating cavity is communicated with the sealing groove, and a part of the heating element is located in the accommodating cavity; The shell is also provided with a shielding plate, the shielding plate covers the cavity opening of the accommodating cavity, and the shielding plate is detachably connected to the pressing plate.
10. The tubular heater according to claim 9, characterized in that: A control cavity and an opening communicating with the control cavity are provided on the upper side wall of the heating end; The housing further comprises a sealing plate and an outlet sealing pad, wherein the outlet sealing pad is arranged on the sealing plate, the sealing plate cover is arranged on the opening, and the outlet hole on the outlet sealing pad is communicated with the control chamber; The housing further comprises a first upper cover plate, the first upper cover plate is covered on the sealing plate, and the first upper cover plate is attached to the upper side wall of the heating end, the first upper cover plate is provided with a first wire groove, and the first wire groove is communicated with the wire outlet hole on the wire outlet sealing pad; The pressing plate is also provided with a second wire groove connected to the accommodating cavity, and the second wire groove is connected to the first wire groove.
11. A vehicle, characterized in that, The tubular heater comprises the tubular heater described in any one of claims 1 to 10.