Sleeve type electric heating device
By adopting multiple sleeve structures in the resistor heating device, the problem of uneven thermal stress distribution and poor thermal exchange performance of thermal stress distribution, and the improvement of the thermal stress uniform distribution and heat exchange performance. It is suitable for high voltage and high power requirements. application.
Patent Information
- Application Number
- CN202411898159.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-01-24
AI Technical Summary
Existing resistive electric heaters have problems with uneven thermal stress distribution and poor heat exchange performance.
It adopts a casing structure, including a shell, an electric heating tube, an inner casing, a middle casing, an outer casing and a connecting tube. The multiple casing structure improves the convection heat transfer coefficient of the fluid and increases the intermediate heat transfer area to achieve Uniformity of heat transfer.
The uniformity of thermal stress distribution and the improvement of thermal extension performance are implemented, and applications for high voltage and high power requirements are suitable for high voltage and high power requirements.
Smart Images
Figure CN119353785A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a resistance electric heater, in particular to a sleeve type electric heating device. Background Art
[0002] Molten salt energy storage is a sensible heat storage technology with the advantages of low price, low vapor pressure, high operating temperature, environmental friendliness and non-flammability. It mainly absorbs energy at low temperatures and releases energy at high temperatures through the sensible heat of molten salt. In the entire operating temperature range, the molten salt always remains liquid.
[0003] The molten salt electric heater is a device that uses electric energy to heat molten salt to a specified temperature. It is one of the core devices of molten salt energy storage. The molten salt electric heater can achieve high-efficiency recovery of abandoned electricity and valley electricity, and is used together with the molten salt pump, cold molten salt tank and hot molten salt tank in the molten salt energy storage system to establish a working process of cold molten salt tank-molten salt pump-electric heater system-hot molten salt tank.
[0004] Resistive electric heater is a common molten salt electric heater, which mainly achieves heating through the resistance heat generated when current flows through a resistance wire or a resistance element. However, the related resistive electric heater has disadvantages such as uneven thermal stress distribution and poor heat exchange performance. Summary of the invention
[0005] Purpose of the invention: The purpose of the present invention is to provide a sleeve-type electric heating device, which has the advantages of uniform thermal stress distribution and good heat exchange performance.
[0006] Technical solution: A sleeve type electric heating device, comprising: case; Electric heating tube; An inner sleeve, wherein at least a portion of the electric heating tube is located inside the inner sleeve; A middle sleeve wrapped around the inner sleeve; An outer sleeve wrapped around the middle sleeve; A plurality of connecting tubes, each connecting tube radially passing through the middle sleeve, one end of each connecting tube being connected to the inner sleeve, and the other end of each connecting tube being connected to the outer sleeve; an inlet pipe connected to one end of the inner sleeve, one end of the middle sleeve and one end of the outer sleeve; an outlet pipe connected to the other end of the inner sleeve; The other ends of the middle sleeve and the outer sleeve are closed, and the inner sleeve, the middle sleeve, the outer sleeve, the connecting tube and at least part of the electric heating tube are all located in the shell.
[0007] Optionally, it further includes a reflux chamber formed between the inner wall of the shell and the outer sleeve, wherein the reflux chamber has an inlet connected to the other end of the inner sleeve and an outlet connected to the outlet pipe.
[0008] Optionally, also include: an inlet header and an outlet header, both connected to the shell; A reflux pipe, one end of which is connected to the outlet header, and the other end of which is connected to the inlet of the reflux chamber; The inlet pipe is connected to one end of the inner sleeve, one end of the middle sleeve and one end of the outer sleeve through the inlet header, the other end of the inner sleeve is connected to the outlet header, and at least part of the electric heating pipe is located in the inlet header and the outlet header.
[0009] Optionally, the inner sleeve comprises: tube body; an inner flow channel disposed in the tube body; Among them, at least part of the electric heating tube is located in the inner flow channel, the middle sleeve is wrapped around the tube body, one end of the connecting tube is connected to the inner flow channel, one end of the inner flow channel is connected to the inlet pipe, and the other end of the inner flow channel is connected to the outlet pipe.
[0010] Optionally, the inner flow channel includes a necking section, and along the fluid flow direction, the necking section has an inner diameter that gradually decreases.
[0011] Optionally, the inner flow channel further includes an acceleration section, and along the fluid flow direction, the minimum inner diameter of the inner flow channel section located before the acceleration section is equal to the inner diameter of the acceleration section.
[0012] Optionally, the inner flow channel further includes a flared section, and along the fluid flow direction, the flared section has an inner diameter that gradually increases.
[0013] Optionally, an inner wall of the tube body is provided with an inner groove connected to the inner flow channel, and the fluid flows through the inner groove to form a vortex.
[0014] Optionally, one end of the connecting tube is connected to the inner groove.
[0015] Optionally, the inner wall of the tube body is provided with a Tesla valve flow channel section connected to the inner flow channel, and the Tesla valve flow channel section is used to divert and re-converge the fluid in the inner flow channel to slow down the overall flow rate.
[0016] Optionally, along the radial direction from the outer sleeve to the inner sleeve, the connecting tube has an inner diameter that gradually decreases.
[0017] The present invention adopts a structure arrangement of multiple sleeves in the housing, and the beneficial effects are as follows: (1) It is beneficial to improve the convective heat transfer coefficient of the fluid, allowing the heat load per unit area of the electric heating tube to be greatly increased, and can be applied to high voltage and high power requirements; (2) It is convenient to increase the intermediate heat transfer area, making the heat transition more uniform, which is conducive to the relatively uniform distribution of thermal stress and ensuring the structural strength. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a schematic structural diagram of a sleeve-type electric heating device according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the fluid flow in a sleeve-type electric heating device according to Embodiment 1 of the present invention; In the figure: 11, distribution box; 12, electric heating tube; 2, inner sleeve; 21, tube body; 22, inner flow channel; 221, necking section; 222, acceleration section; 223, inner groove; 2231, groove section; 224, expansion section; 225, Tesla valve flow channel section; 3, middle sleeve; 4, outer sleeve; 5, connecting pipe; 61, inlet pipe; 62, outlet pipe; 7, shell; 71, reflux chamber; 711, inlet; 712, outlet; 72, inlet header; 73, outlet header; 74, reflux pipe. DETAILED DESCRIPTION
[0019] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.
[0020] Example 1
[0021] like Figure 1-Figure 2 The present embodiment provides a sleeve-type electric heating device, comprising: a shell 7; an electric heating tube 12; an inner sleeve 2, at least part of the electric heating tube 12 is located in the inner sleeve 2; a middle sleeve 3 sheathed outside the inner sleeve 2; an outer sleeve 4 sheathed outside the middle sleeve 3; a plurality of connecting tubes 5, the connecting tubes 5 radially passing through the middle sleeve 3, one end of the connecting tube 5 being connected to the inner sleeve 2, and the other end of the connecting tube 5 being connected to the outer sleeve 4; an inlet pipe 61 connected to one end of the inner sleeve 2, one end of the middle sleeve 3 and one end of the outer sleeve 4; an outlet pipe 62 connected to the other end of the inner sleeve 2; wherein the other ends of the middle sleeve 3 and the outer sleeve 4 are closed, and the inner sleeve 2, the middle sleeve 3, the outer sleeve 4, the connecting tube 5 and at least part of the electric heating tube 12 are all located in the shell 7.
[0022] Specifically, during heating, molten salt and other fluids flow from the inlet pipe 61 into one end of the inner sleeve 2, one end of the middle sleeve 3 and one end of the outer sleeve 4, wherein the fluid flowing into the inner sleeve 2 is heated by the electric heating pipe 12 and then flows out through the outlet pipe 62, the fluid flowing into the middle sleeve 3 fills the entire middle sleeve 3, the fluid flowing into the outer sleeve 4 fills the entire outer sleeve 4, and flows into the inner sleeve 2 through the connecting pipe 5.
[0023] The shell 7 is used to accommodate the inner sleeve 2, the middle sleeve 3, the outer sleeve 4, the connecting tube 5 and at least part of the electric heating tube 12, etc., so as to provide protection for the inner sleeve 2, the middle sleeve 3, the outer sleeve 4, the connecting tube 5 and at least part of the electric heating tube 12; the electric heating tube 12 is used to heat the fluid in the inner sleeve 2, so as to store energy of the fluid. The electric heating tube 12 can be a resistance type electric heating tube such as a resistance wire type or an electric heating tube type. The electric heating tube 12 is electrically connected to the relevant distribution box 11, so as to provide the electric heating tube 12 with a heat dissipation function. The inner sleeve 2 is used to accommodate the electric heating tube 12 and the fluid, so that the electric heating tube 12 can heat the fluid; the middle sleeve 3 is used to be filled with the fluid. Since the other end of the middle sleeve 3 is closed, the fluid from the inlet pipe 61 cannot flow out after entering the middle sleeve 3. The middle sleeve 3 has the following effects: first, the fluid in the middle sleeve 3 has a certain temperature under the heating of the fluid in the inner sleeve 2, has good thermal insulation performance, and reduces heat loss; second, the fluid in the middle sleeve 3 has a certain temperature when it first enters the outer sleeve 2. The fluids in the sleeve 4 and the inner sleeve 2 are preliminarily heated. Thirdly, the fluid in the middle sleeve 3 reduces the temperature difference between the metal sleeves of the inner wall of the outer sleeve 4 and the outer wall of the inner sleeve 2, reduces the deformation of the metal sleeves caused by the thermal stress difference, and prolongs the service life. Fourthly, the middle sleeve 3 combines with the inner sleeve 2 and the outer sleeve 4 to form a multi-overlapping sleeve type, which is convenient for increasing the intermediate heat transfer area, making the heat transition more uniform, and is conducive to the relatively uniform distribution of thermal stress, thereby ensuring the structural strength. Since the other end of the outer sleeve 4 is closed, it is equivalent to that the fluid from the inlet pipe 61 can only flow out from a number of connecting pipes 5 after entering the outer sleeve 4. The outer sleeve 4 cooperates with a number of connecting pipes 5, which is convenient for the fluid entering the inner sleeve 2 from the outer sleeve 4 and a number of connecting pipes 5 and the fluid of the inner sleeve 2 itself to form an impact jet, which is convenient for strengthening heat exchange and making the heat exchange performance good. Among them, the number of connecting pipes 5 can be flexibly set according to actual needs, and the connecting pipes 5 are arranged at intervals along the axial direction and circumferential direction of the inner sleeve 2. The inlet pipe 61 is used for fluid inflow, and the outlet pipe 62 is used for fluid outflow.
[0024] Further, such as Figure 1-Figure 2 , and also includes a reflux chamber 71 formed between the inner wall of the shell 7 and the outer sleeve 4, the reflux chamber 71 having an inlet 711 connected to the other end of the inner sleeve 2 and an outlet 712 connected to the outlet pipe 62.
[0025] Specifically, the reflux chamber 71 facilitates the formation of a countercurrent of the fluid at the time of inlet and outlet, so that the heated fluid in the reflux chamber 71 heats the fluid that has just entered the outer sleeve 4. The reflux chamber 71 also has the following effects. First, the heated fluid fills the reflux chamber 71, so that there is no obvious temperature gradient between the temperature of the shell 7 and the outer wall of the outer sleeve 4, which is conducive to forming a relatively stable temperature environment. Under the conditions of relatively stable temperature and small temperature difference in various regions, the thermal deformation of the metal materials at various locations of the shell 7 that contact the fluid is similar, and it is not easy to cause the concentration of thermal stress of the metal material caused by the difference in thermal deformation, resulting in a decrease in the strength of the metal material or fracture, thereby ensuring the structural strength and stability. Second, the fluid is fully mixed in the reflux chamber 71, which is conducive to significantly improving the uniformity of the fluid temperature.
[0026] Further, such as Figure 1-Figure 2 , and also includes: an inlet header 72 and an outlet header 73 both connected to the shell 7; a return pipe 74, one end of the return pipe 74 is connected to the outlet header 73, and the other end of the return pipe 74 is connected to the inlet 711 of the reflux chamber 71; wherein the inlet pipe 61 is connected to one end of the inner sleeve 2, one end of the middle sleeve 3 and one end of the outer sleeve 4 through the inlet header 72, the other end of the inner sleeve 2 is connected to the outlet header 73, and at least part of the electric heating tube 12 is located in the inlet header 72 and the outlet header 73.
[0027] Specifically, the inlet manifold 72 is used to cache the fluid, so as to facilitate the fluid to flow synchronously and evenly into one end of the inner sleeve 2, one end of the middle sleeve 3 and one end of the outer sleeve 4. The inlet pipe 61 is preferably directly arranged on the inlet manifold 72; the outlet manifold 73 is used to cache the fluid, so as to facilitate the fluid to flow evenly into the return pipe 74; the return pipe 74 is used to connect the outlet manifold 73 and the return chamber 71.
[0028] Further, such as Figure 1-Figure 2 The inner sleeve 2 includes: a tube body 21; an inner flow channel 22 arranged in the tube body 21; wherein, at least part of the electric heating tube 12 is located in the inner flow channel 22, the middle sleeve 3 is wrapped around the tube body 21, one end of the connecting pipe 5 is connected to the inner flow channel 22, one end of the inner flow channel 22 is connected to the inlet pipe 61, and the other end of the inner flow channel 22 is connected to the outlet pipe 62.
[0029] Further, such as Figure 1-Figure 2 The inner flow channel 22 includes a constricted section 221, and along the fluid flow direction, the constricted section 221 has an inner diameter that gradually decreases.
[0030] Specifically, the tapered section 221 facilitates the gradual acceleration of the fluid, thereby increasing the Reynolds number, improving the convective heat transfer coefficient, enhancing heat transfer, and improving the heat transfer performance; the inner flow channel 22 may only include the tapered section 221, that is, one end of the tapered section 221 is connected to the inlet manifold 72, and the other end of the tapered section 221 is connected to the outlet manifold 73. Preferably, along the fluid flow direction, the inner flow channel 22 simultaneously includes the tapered section 221 and other sections that are connected in sequence, that is, one end of the tapered section 221 is connected to the inlet manifold 72, and the other end of the tapered section 221 is connected to the outlet manifold 73 through other sections; along the fluid flow direction, the inner diameter of the tapered section 221 only needs to generally present a gradually decreasing shape, and can be gradually reduced evenly (such as the tapered section 221 is a truncated cone), or can be gradually reduced unevenly (such as the tapered section 221 is a cylindrical plus truncated cone).
[0031] Further, such as Figure 1-Figure 2 The inner flow channel 22 also includes an acceleration section 222 . Along the fluid flow direction, the minimum inner diameter of the section of the inner flow channel 22 located before the acceleration section 222 is equal to the inner diameter of the acceleration section 222 .
[0032] Specifically, the acceleration section 222 facilitates making the fluid flow rate relatively fast and significantly enhancing the heat exchange effect; the inner flow channel 22 may only include the acceleration section 222, that is, one end of the acceleration section 222 is connected to the inlet manifold 72, and the other end of the acceleration section 222 is connected to the outlet manifold 73. Preferably, along the fluid flow direction, the inner flow channel 22 simultaneously includes the necking section 221, the acceleration section 222 and other sections that are connected in sequence, that is, the end of the necking section 221 away from the acceleration section 222 is connected to the inlet manifold 72, and the ends of the other sections away from the acceleration section 222 are connected to the outlet manifold 73; the inner diameter of the acceleration section 222 itself remains unchanged.
[0033] Further, such as Figure 1-Figure 2 The inner flow channel 22 also includes a flared section 224, and along the fluid flow direction, the flared section 224 has an inner diameter that gradually increases.
[0034] Specifically, the flaring section 224 is used to gradually decelerate the fluid; the inner flow channel 22 may only include the flaring section 224, that is, one end of the flaring section 224 is connected to the inlet manifold 72, and the other end of the flaring section 224 is connected to the outlet manifold 73; preferably, along the fluid flow direction, the inner flow channel 22 simultaneously includes a constricting section 221, an accelerating section 222 and a flaring section 224 that are connected in sequence, that is, the end of the constricting section 221 away from the accelerating section 222 is connected to the inlet manifold 72, and the end of the flaring section 224 away from the accelerating section 222 is connected to the outlet manifold 73, so that the fluid from the flaring section 224 slowly and evenly enters the outlet manifold 73 to prevent a large impact on the outlet manifold 73; along the fluid flow direction, the inner diameter of the flaring section 224 only needs to generally present a gradually increasing shape, and can be gradually increased evenly (such as the flaring section 224 is a truncated cone), or can be gradually increased unevenly (such as the flaring section 224 is a cylindrical plus truncated cone).
[0035] Further, such as Figure 1-Figure 2 The inner wall of the tube body 21 is provided with an inner groove 223 which is connected with the inner flow channel 22, and the fluid flows through the inner groove 223 to form a vortex.
[0036] Specifically, the inner groove 223 utilizes the principle of the flow channel expansion and contraction structure to form vortices, which is convenient for increasing the degree of fluid turbulence and enhancing heat exchange; along the fluid flow direction, the inner grooves 223 are preferably arranged in multiple intervals, and are preferably arranged in the acceleration section 222, so that the inner flow channel 22 adopts an expansion and contraction interval arrangement, which is convenient for avoiding vibration of the tube body 21 caused by excessive fluid flow rate, ensuring structural safety, and avoiding excessive flow resistance caused by excessive flow rate.
[0037] Further, such as Figure 1-Figure 2 , one end of the connecting pipe 5 is connected to the inner groove 223. Specifically, it is convenient to make the fluid in the connecting pipe 5 flow into the inner groove 223, thereby pushing the eddy current in the inner groove 223 forward and avoiding the eddy current from being retained.
[0038] Further, the inner groove 223 is a continuous or spaced groove segment 2231 on the circumference of the inner wall of the pipe body 21. Specifically, the continuous groove segment 2231 may be annular or spiral, and the intervals between the spaced groove segments 2231 are preferably equal.
[0039] Further, such as Figure 1-Figure 2 The inner wall of the tube body 21 is provided with a Tesla valve flow channel section 225 connected to the inner flow channel 22. The Tesla valve flow channel section 225 is used to divert and re-converge the fluid in the inner flow channel 22 to slow down the overall flow rate.
[0040] Specifically, one end of the Tesla valve flow channel section 225 is preferably connected to the connection point between the acceleration section 222 and the expansion section 224, and the other end of the Tesla valve flow channel section 225 is preferably connected to the connection point between the expansion section 224 and the outlet manifold 73, so that the fluid flowing out of the Tesla valve flow channel section 225 and the fluid flowing out of the expansion section 224 collide with each other, thereby forming a confluence, which is convenient for decelerating the fluid, thereby facilitating the uniform buffering of the fluid in the outlet manifold 73.
[0041] Further, such as Figure 1-Figure 2 Along the radial direction from the outer sleeve 4 to the inner sleeve 2, the connecting tube 5 has an inner diameter that gradually decreases.
[0042] Specifically, it is convenient to gradually increase the flow rate of the fluid in the connecting pipe 5, which is equivalent to making the connecting pipe 5 in the shape of a nozzle, so as to further form an impact jet, enhance heat exchange, and achieve good heat exchange performance; along the radial direction from the outer sleeve 4 to the inner sleeve 2, the inner diameter of the connecting pipe 5 only needs to generally present a gradually decreasing shape, which can be gradually reduced evenly (such as the connecting pipe 5 is a truncated cone shape) or unevenly (such as the connecting pipe 5 is a cylindrical plus truncated cone shape).
[0043] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.
Claims
1. A sleeve-type electric heating device, characterized in that: include: Housing (7); Electric heating tube (12); An inner sleeve (2), wherein at least a portion of the electric heating tube (12) is located inside the inner sleeve (2); A middle sleeve (3) sheathed outside the inner sleeve (2); An outer sleeve (4) sheathed outside the middle sleeve (3); a plurality of connecting tubes (5), wherein the connecting tubes (5) radially pass through the middle sleeve (3), one end of the connecting tube (5) is connected to the inner sleeve (2), and the other end of the connecting tube (5) is connected to the outer sleeve (4); an inlet pipe (61) connected to one end of the inner sleeve (2), one end of the middle sleeve (3) and one end of the outer sleeve (4); an outlet pipe (62) connected to the other end of the inner sleeve (2); The other ends of the middle sleeve (3) and the outer sleeve (4) are closed, and the inner sleeve (2), the middle sleeve (3), the outer sleeve (4), the connecting tube (5) and at least part of the electric heating tube (12) are all located inside the shell (7).
2. A sleeve-type electric heating device according to claim 1, characterized in that: It also includes a reflux chamber (71) formed between the inner wall of the shell (7) and the outer sleeve (4), the reflux chamber (71) having an inlet (711) connected to the other end of the inner sleeve (2) and an outlet (712) connected to the outlet pipe (62).
3. A sleeve-type electric heating device according to claim 2, characterized in that: Also includes: an inlet header (72) and an outlet header (73) both connected to the housing (7); a return pipe (74), one end of the return pipe (74) being in communication with the outlet header (73), and the other end of the return pipe (74) being in communication with the inlet (711) of the return chamber (71); The inlet pipe (61) is connected to one end of the inner sleeve (2), one end of the middle sleeve (3) and one end of the outer sleeve (4) via the inlet header (72), the other end of the inner sleeve (2) is connected to the outlet header (73), and at least part of the electric heating pipe (12) is located in the inlet header (72) and the outlet header (73).
4. A sleeve-type electric heating device according to any one of claims 1 to 3, characterized in that: The inner sleeve (2) comprises: tube body(21); an inner flow channel (22) disposed in the tube body (21); In which, at least a portion of the electric heating tube (12) is located in the inner flow channel (22), the middle sleeve (3) is wrapped around the outside of the tube body (21), one end of the connecting tube (5) is connected to the inner flow channel (22), one end of the inner flow channel (22) is connected to the inlet pipe (61), and the other end of the inner flow channel (22) is connected to the outlet pipe (62).
5. A sleeve-type electric heating device according to claim 4, characterized in that: The inner flow channel (22) comprises a constricted section (221), and along the fluid flow direction, the constricted section (221) is in a state where the inner diameter gradually decreases.
6. A sleeve-type electric heating device according to claim 4, characterized in that: The inner flow channel (22) further comprises an acceleration section (222), and along the fluid flow direction, the minimum inner diameter of the section of the inner flow channel (22) located before the acceleration section (222) is equal to the inner diameter of the acceleration section (222).
7. A sleeve-type electric heating device according to claim 4, characterized in that: The inner flow channel (22) further comprises a flared section (224), and along the fluid flow direction, the flared section (224) is in a form in which the inner diameter gradually increases.
8. A sleeve-type electric heating device according to claim 4, characterized in that: The inner wall of the tube body (21) is provided with an inner groove (223) which is in communication with the inner flow channel (22), and the fluid flows through the inner groove (223) to form a vortex.
9. A sleeve-type electric heating device according to claim 8, characterized in that: One end of the connecting pipe (5) is in communication with the inner groove (223).
10. The sleeve-type electric heating device according to claim 4, characterized in that: The inner wall of the tube body (21) is provided with a Tesla valve flow channel section (225) connected to the inner flow channel (22), and the Tesla valve flow channel section (225) is used to divide and re-converge the fluid in the inner flow channel (22) so as to slow down the overall flow rate.
11. A sleeve-type electric heating device according to any one of claims 1 to 3, characterized in that: Along the radial direction from the outer sleeve (4) to the inner sleeve (2), the connecting tube (5) is in a state in which the inner diameter gradually decreases.