Gas heater

Abstract

The utility model discloses a gas heater, and relates to the field of fuel cells, the gas heater comprises a hollow heat conduction sleeve and a heating part arranged in the heat conduction sleeve, the heat conduction sleeve and the heating part are fixedly clamped through a detachable positioning hoop assembly; the heating part comprises a heating rod which is distributed along the central axis direction of the heat conduction sleeve and fins which are spirally distributed on the outer side wall of the heating rod; the heating rod comprises an outer pipe body of a composite layer structure and a heating wire fixed in the inner space of the outer pipe body. The heating component is coupled and positioned in the heat conduction sleeve, so that an effective positioning and fixing effect on the heating component is achieved; the heat exchange area in the heating rod and the heat conduction sleeve is increased, the heat capacity is increased, and the heat exchange efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the field of fuel cells, in particular to a gas heater. Background Art

[0002] Proton exchange membrane fuel cells are the most efficient devices for generating electricity using hydrogen energy. They have the advantages of high conversion efficiency and no pollution, and have broad application prospects. In the process of fuel cell development and testing, it is necessary to simulate various environmental and operating parameters. Among them, gas heating control in water thermal management is an important part of fuel cells, and efficient temperature control is the key factor in accurately testing fuel cells.

[0003] To maintain the temperature of the proton exchange membrane, the fuel cell system needs a heater to heat the reaction gas to improve performance. However, too low or too high gas temperature will cause the system efficiency to decrease or the membrane to dry out, thus affecting normal operation. Therefore, the test platform must accurately control the temperature of the reaction gas entering the battery pack to ensure that the gas is in a suitable state.

[0004] In the patent CN208317038U "A new type of electric heating rod", an electric heating rod is provided that can accurately simulate the actual heat source density distribution, but there are problems such as low heat exchange efficiency and the heating rod is prone to position deviation, resulting in local temperature overshoot. Utility Model Content

[0005] The technical problem to be solved by the utility model is how to improve the heat exchange efficiency of the gas heater and avoid displacement of the internal heating components.

[0006] The utility model solves the above technical problems through the following technical solutions: a gas heater comprises a hollow heat-conducting sleeve and a heating component arranged in the heat-conducting sleeve, wherein the heating component and the heat-conducting sleeve are fixedly connected by a detachable positioning clamp assembly;

[0007] The heating component comprises a heating rod distributed along the central axis direction of the heat-conducting sleeve and fins distributed in a spiral shape on the outer side wall of the heating rod.

[0008] The heating component is coupled and positioned in the heat-conducting sleeve through a detachable positioning clamp assembly, which effectively positions and fixes the heating component; the gas heater is provided with fins on the outer wall of the heating rod, which increases the heat exchange area between the heating rod and the heat-conducting sleeve, increases the heat capacity, and improves the heat exchange efficiency.

[0009] The heating rod comprises an outer tube body of a composite layer structure and a heating wire fixed in the inner space of the outer tube body.

[0010] The outer tube body of the composite layer structure comprises an outer shell layer and an insulating layer.

[0011] The insulating layer is made of magnesium oxide powder with a purity of ≥99% sealed by epoxy resin.

[0012] Magnesium oxide powder has good thermal conductivity and stable and reliable electrical insulation performance, which makes the surface of the heating rod non-electrical, increases the safety of the gas heater, and can fix the position of the heating wire in space to prevent the heating wire from shifting or breaking due to vibration or other reasons. The extremely high purity magnesium oxide powder ensures that the heating rod will not break down or flash over when the AC current test is 1500V / min during the electrical withstand voltage test. Even under high temperature conditions of 600℃, its insulation resistance can still be maintained above 50MΩ;

[0013] The epoxy resin material is used for curing and sealing, which can effectively prevent the magnesium oxide powder from absorbing moisture, avoiding the risk of insulation performance degradation and leakage current when the heating rod works for a long time;

[0014] The heat-conducting sleeve is opened at both ends, one end is a gas inlet, and the other end is a gas outlet;

[0015] The fins are distributed in a spiral shape with equal pitches.

[0016] The spiral fins with equal pitch keep the heat flux density of each part of the heating rod consistent, ensuring the uniform change of the heat flux density along the length direction, thus improving the heating and heat dissipation performance of the heating rod;

[0017] The outer tube body of the heating rod, the outer shell of the heat-conducting sleeve and the fins are all made of 316L stainless steel.

[0018] Stainless steel has good weldability, high hardness and strength, and can withstand greater friction and impact.

[0019] The heating wire is made of nickel-chromium alloy material.

[0020] The nickel-chromium alloy material enables the heat flux density emitted by the heating wire to vary uniformly along the center line of the heat-conducting sleeve in the transverse direction.

[0021] The positioning clamp assembly further comprises a silicone gasket, which is a sealing gasket in contact between the heating rod and the heat-conducting sleeve;

[0022] When the temperature of the gas heater is not higher than 150°C, the sealing gasket made of silicone has low cost and good heat resistance. It can be used permanently below 150°C without performance changes, and has good oxidation resistance when in contact with air.

[0023] The fin is fixed to the outer wall of the heating rod by spot welding. The thickness of the fin is 0.4 mm, the height is 7 mm, and the pitch range is 5-25 mm.

[0024] The fins are wound around the surface of the heating rod by spot welding, which can keep the heat flux density of each part of the heating component consistent and meet the uniform change of heat flux density along the length direction. Fin pitches in different ranges can adapt to a wider range of medium temperature control requirements.

[0025] The beneficial effects of the utility model are:

[0026] 1. The heating component is coupled and positioned in the heat-conducting sleeve through a detachable positioning clamp assembly, which effectively positions and fixes the heating component; the gas heater is provided with fins on the outer wall of the heating rod, which increases the heat exchange area between the heating rod and the heat-conducting sleeve, increases the heat capacity, and improves the heat exchange efficiency.

[0027] 2. Magnesium oxide powder has good thermal conductivity and stable and reliable electrical insulation performance, which makes the surface of the heating tube non-electrical, increases the safety of the gas heater, and can fix the position of the heating wire in space to prevent the heating wire from shifting or breaking due to vibration or other reasons; extremely high purity magnesium oxide powder ensures that the heating rod will not break down or flash over when the AC current test is 1500V / min during the electrical withstand voltage test. Even under high temperature conditions of 600℃, its insulation resistance can still be maintained above 50MΩ.

[0028] 3. The use of epoxy resin material for curing and sealing can effectively prevent the magnesium oxide powder from absorbing moisture, avoiding the risk of insulation performance degradation and leakage current when the heating rod works for a long time.

[0029] 4. The spiral fins with equal pitch keep the heat flux density of each part of the heating rod consistent, meet the uniform change of heat flux density along the length direction, and improve the heating and heat dissipation performance of the heating rod.

[0030] 5. The outer tube of the heating rod, the shell of the heat-conducting sleeve and the fins are all made of 316L stainless steel, which has good weldability, high hardness and strength, and can withstand greater friction and impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of a finless gas heater in Example 1 of the utility model;

[0032] Figure 2 This is a schematic structural diagram of a gas heater with a fin pitch of 5 mm in Example 1 of the utility model;

[0033] Figure 3 This is a disassembled structural diagram of the positioning hoop assembly in Example 1 of the utility model;

[0034] Figure 4 This is a schematic diagram of the structure of a gas heater with a fin pitch of 15 mm in Example 2 of the utility model;

[0035] Figure 5 This is a schematic diagram of the structure of a gas heater with a fin pitch of 25 mm in Example 3 of the utility model.

[0036] Numbers in the figure: 1. Heating rod; 2. Heat-conducting sleeve; 3. Gas inlet; 4. Gas outlet; 5. Fin; 6. Silicone gasket; 7. Positioning clamp assembly. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model are clearly and completely described. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0038] Embodiment 1:

[0039] See also Figure 1 A gas heater comprises a hollow heat-conducting sleeve 2 and a heating component arranged in the heat-conducting sleeve 2. The heat-conducting sleeve 2 is opened at both ends, one end is a gas inlet 3, and the other end is a gas outlet 4. The heating component comprises a heating rod 1 distributed along the central axis direction of the heat-conducting sleeve 2 and fins 5 distributed in a spiral shape on the outer wall of the heating rod 1; the heating rod 1 comprises an outer tube body with a composite layer structure and a heating wire (not shown) fixed in the inner space of the outer tube body.

[0040] The outer tube body of the composite layer structure includes an outer shell layer and an insulating layer (not shown in the figure). The insulating layer uses epoxy resin material to seal magnesium oxide powder with a purity of ≥99% inside, thereby insulating the heating wire from the outer tube body. The outer tube body is a stainless steel tube, and the heating wire material is a nickel-chromium alloy with a maximum temperature of 1200°C and excellent linearity and processing ductility. The filled magnesium oxide powder is a good thermal conductive material with stable and reliable electrical insulation performance, and is also used to fix the position of the heating wire. The sealing method uses epoxy resin material for secondary curing insulation sealing, which can effectively prevent the magnesium oxide powder from absorbing moisture, thereby avoiding the risk of reduced insulation performance and increased leakage current when the heating rod 1 works for a long time.

[0041] A reserved gap (not shown) is provided between the heating rod 1 and the side wall of the heat-conducting sleeve 2. The reserved gap is selected according to different design conditions and heat-conducting sleeves of different diameters. The smaller the diameter of the heat-conducting sleeve, the smaller the reserved gap, the faster the response time of heat transfer, and the smaller the hysteresis. Figure 2As shown, the fins 5 in the heating component are wound around the outer wall of the heating rod 1 by spot welding, and are distributed in a spiral shape with equal pitches. The weld nodes are subjected to pickling and other passivation processes, so that the heating component is guaranteed to be rust-free for a long time in a deionized water medium environment. The specific pickling and other passivation processes include: first grinding the welding nodes of the fins 5 to remove impurities, immersing them in a pickling passivation solution to form a passivation film to improve corrosion resistance, then rinsing the pickling solution and passivation solution, rinsing with pure water to remove acidic substances, and drying to prevent corrosion, which can effectively remove oxide scale, improve appearance and corrosion resistance, and enhance the corrosion resistance of the weld between the heater and the fins.

[0042] The thickness of the fin 5 is 0.4 mm, the height is 7 mm, and the pitch is 5 mm, which increases the heat transfer and heat dissipation area of ​​the heating rod 1 and the heat capacity, and facilitates the rapid absorption and heat dissipation of the gas in the thermal sleeve 2. The fins 5 with equal pitch keep the heat flux density of each part of the heating rod 1 consistent, meet the uniform change of the heat flux density along the length direction, and improve the heating and heat dissipation performance of the heating rod 1.

[0043] Operation principle: When the gas passes through the gas heater, the heating component transfers heat to the fins 5 by convection, and the fins 5 heat the air inside the thermal sleeve 2 by forced convection and radiation to achieve smooth heat transfer.

[0044] Specifically, the heat energy is transferred from the magnesium oxide layer inside the heating rod 1 to the external stainless steel layer by heat conduction, and then the heat is transferred to the flowing gas side inside the heat-conducting sleeve 2 by heat convection, so that the low-temperature gas close to the outer tube body of the heating rod 1 absorbs the heat.

[0045] Specifically, the outer tube body of the heating rod 1, the outer shell of the heat-conducting sleeve 2 and the fins 5 are all made of 316L stainless steel. The 316L stainless steel material has good weldability, which is convenient for the later processing of the fins 5. It has high hardness and strength and can withstand greater friction and impact. The heating wire in the heating rod 1 is made of nickel-chromium alloy material, so that the heat flux density emitted by the heating wire changes uniformly along the center line of the heat-conducting sleeve 2 in the transverse direction.

[0046] The heating component and the heat-conducting sleeve 2 are fixedly connected by a detachable positioning clamp assembly 7, and the positioning clamp assembly 7 has a structure as shown in FIG. Figure 3 As shown,

[0047] The positioning clamp assembly 7 includes a clamp part, a bolt and a nut. The two ends of the clamp part can be movably hinged and bent. The clamp part is opened to clamp the heating component. The nut and the bolt are movably connected through threads. The nut locks the bolt to enable the positioning clamp assembly 7 to limit and tighten the heating component to prevent the heating component from being displaced in the heat-conducting sleeve 2, resulting in uneven internal heating and causing local damage to the heat-conducting sleeve 2.

[0048] The positioning clamp assembly 7 also includes a silicone gasket 6, which is a sealing gasket contacting the heating rod 1 and the thermal sleeve 2. When the temperature of the gas heater is not higher than 150°C, the sealing gasket made of silicone has low cost and good heat resistance, can be used permanently below 150°C without performance changes, and has good oxidation resistance when in contact with air.

[0049] Embodiment 2:

[0050] Based on Example 1, the pitch of fin 5 is adjusted to 15 mm. Figure 4 As shown, the purity of the magnesium oxide powder is 99.5%.

[0051] The larger the pitch of the fin 5, the higher the temperature of the heating rod at the same heating power, the more heat is stored, and the greater the temperature overshoot; the smaller the pitch, the lower the temperature of the heating rod 1 at the same heating power, the less heat is stored, the smaller the temperature overshoot, and finally the high-temperature gas is discharged from the outlet. During the cooling process, the heating rod 1 is turned off, and the external low-temperature gas enters from the inlet, flows through the reserved gap, takes away the residual heat of the heating rod 1, and improves the heat dissipation efficiency.

[0052] The extremely high purity magnesium oxide powder ensures that the heating rod 1 will not break down or flash over when the AC current test is 1500V / min during the electrical withstand voltage test. Even under the high temperature of 600°C, its insulation resistance can still be maintained above 50MΩ.

[0053] Embodiment 3:

[0054] On the basis of Example 1, the pitch of fin 5 is adjusted to 25 mm. Figure 5 As shown, the purity of the magnesium oxide powder is 99.3%.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A gas heater, comprising a hollow heat-conducting sleeve (2) and a heating component arranged in the heat-conducting sleeve, characterized in that: The heat-conducting sleeve (2) and the heating component are fixedly connected by a detachable positioning clamp assembly (7); The heating component comprises a heating rod (1) distributed along the central axis direction of the heat-conducting sleeve (2) and fins (5) distributed in a spiral shape on the outer wall of the heating rod (1); The heating rod (1) comprises an outer tube body of a composite layer structure and a heating wire fixed in the inner space of the outer tube body.

2. A gas heater according to claim 1, characterized in that: The outer tube body of the composite layer structure comprises an outer shell layer and an insulating layer.

3. A gas heater according to claim 1, characterized in that: The heat-conducting sleeve (2) is opened at both ends, one end is a gas inlet (3), and the other end is a gas outlet (4).

4. A gas heater according to claim 1, characterized in that: The fins (5) are distributed in a spiral shape with equal pitch.

5. A gas heater according to claim 1, characterized in that: The outer tube body of the heating rod (1), the outer shell of the heat-conducting sleeve (2) and the fins (5) are all made of 316L stainless steel.

6. A gas heater according to claim 1, characterized in that: The heating wire is made of nickel-chromium alloy material.

7. A gas heater according to claim 1, characterized in that: The positioning clamp assembly (7) comprises a silicone gasket, and the silicone gasket is arranged between the heating rod (1) and the heat-conducting sleeve (2).

8. A gas heater according to claim 1, characterized in that: The fins (5) are spot welded on the outer side wall of the heating rod (1).

9. A gas heater according to claim 1, characterized in that: The fin (5) has a thickness of 0.4 mm, a height of 7 mm, and a pitch range of 5-25 mm.

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