Tail gas thermoelectric generator with perforated plate structure

Abstract

The invention belongs to the field of waste heat recovery, and particularly relates to a tail gas thermoelectric generator with a perforated plate structure, which comprises a tail gas heat exchanger, a perforated plate, a thermoelectric module and a cooling water heat exchanger, the thermoelectric module is arranged between the tail gas heat exchanger and the cooling water heat exchanger, and the perforated plate is arranged in the tail gas heat exchanger. The number of the perforated plates is set according to the number of the thermoelectric modules, the thermoelectric modules are arranged in n rows in the tail gas flowing direction, the number of the perforated plates is m, when the row number n of the thermoelectric modules is larger than or equal to 2 and smaller than or equal to 3, the perforated plates are arranged in the middle of the thermoelectric modules in the second row, and when the row number n of the thermoelectric modules is larger than or equal to 4, the perforated plates are arranged in the middle of the thermoelectric modules in the second row. And the perforated plate is arranged in the middle of the thermoelectric module with the multiple of 3. The performance of the tail gas thermoelectric generator can be effectively improved, the surface temperature non-uniformity of the generator is improved, and the equipment reliability is improved.

Description

Technical Field

[0001] The invention belongs to the field of waste heat recovery, and in particular relates to a tail gas temperature difference generator with a porous plate structure. Background Art

[0002] The thermal efficiency of an internal combustion engine is generally around 30% to 40%, and about 30% of the heat is discharged into the environment in the form of exhaust gas, resulting in resource waste and environmental pollution. Thermoelectric generator is a solid-state energy conversion device based on the Seebeck effect. It has the advantages of compact structure, no power components, and basically no maintenance. It can effectively recover the waste heat of exhaust gas for power generation, improve fuel economy, and reduce environmental pollution. Traditional exhaust gas temperature difference generators are mostly "sandwich" structures. The thermoelectric power generation module is placed between the exhaust gas heat exchanger and the cooling water heat exchanger. The temperature difference at both ends of the thermoelectric power generation module generates a voltage to supply power to the external load. However, due to the poor heat transfer performance of the exhaust gas heat exchanger, the heat transfer thermal resistance of the exhaust gas is large, and the temperature of the hot end of the module is much lower than the exhaust gas temperature. Considering that the greater the temperature difference between the hot and cold ends of the module, the higher the power generation efficiency is, the inefficient exhaust gas heat exchanger makes the power generation efficiency of the thermoelectric generator far lower than the theoretical value, which seriously affects the application and promotion of the exhaust gas temperature difference generator.

[0003] Strengthening the heat transfer performance on the exhaust side has become an effective way to improve the thermoelectric performance of the thermoelectric generator. For example, the Chinese patent with patent number CN200997576Y uses semiconductor thermoelectric materials directly laid on the outer wall of the exhaust pipe. Although it can use the temperature difference of the exhaust gas to generate electricity, the heat transfer on the exhaust side is poor, the power generation performance is poor, and due to the gradual decrease in the exhaust temperature, the surface temperature distribution is uneven, which also poses a challenge to the safe and efficient operation of the generator. The Chinese patent with patent number CN201369695Y adds heat pipes to the exhaust heat exchanger, and improves the recovery efficiency of the waste heat of the exhaust gas by strengthening the heat transfer of the gas, but the heat pipe is expensive and easy to wear and replace, and the maintenance cost is greatly increased. The Chinese patent with patent number CN201623673U uses an "S"-shaped spoiler channel to increase the heat exchange of automobile exhaust in the heat exchange section, but this fin structure will bring a large resistance pressure drop, which may affect the normal operation of the engine. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present application proposes an exhaust gas temperature difference generator with a porous plate structure. The present application uses a simple structure and low-cost porous plate filled in the exhaust gas heat exchanger, which can not only effectively improve the performance of the exhaust gas temperature difference generator and improve the economy, but also significantly improve the surface temperature non-uniformity of the generator and improve the reliability of the equipment.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A tail gas temperature difference generator with a porous plate structure comprises a tail gas heat exchanger, a porous plate, a thermoelectric module and a cooling water heat exchanger, wherein the thermoelectric module is installed between the tail gas heat exchanger and the cooling water heat exchanger, the porous plate is arranged in the tail gas heat exchanger and can fully cover the flow channel section of the tail gas heat exchanger, the number of the porous plates is set according to the number of the thermoelectric modules, the thermoelectric modules are arranged in n rows along the exhaust gas flow direction, the number of the porous plates is m, when the number of rows of the thermoelectric modules is 2≤n≤3, the porous plate is arranged in the middle of the second row of thermoelectric modules, and when the number of rows of the thermoelectric modules is n≥4, the porous plate is arranged in the middle of the thermoelectric modules which are multiples of 3.

[0007] Furthermore, a perforated bottom plate is provided at the bottom of the porous plate, a long slot is provided on the exhaust gas heat exchanger, the porous plate is inserted into the exhaust gas heat exchanger through the long slot, and the perforated bottom plate is fixed to the long slot of the exhaust gas heat exchanger by bolts.

[0008] Furthermore, thermal conductive silicone grease or graphite sheets are applied to both ends of the thermoelectric module.

[0009] Furthermore, the holes on the porous plate are arranged in a regular triangle shape, and the hole diameter is 1-5 mm.

[0010] Furthermore, the porosity of the porous plate is 20%-40%.

[0011] Furthermore, the thickness of the porous plate is 1-2 mm.

[0012] Furthermore, the porous plate is made of stainless steel, copper or brass.

[0013] Compared with the existing tail gas temperature difference power generation device, the beneficial effects of the present invention are:

[0014] 1. The porous plate of the present invention has a simple structure, low processing cost, and the material is easily available and can be mass-produced. In addition, the number of porous plates used in the tail gas temperature difference generator is relatively small, which greatly reduces the process cost.

[0015] 2. The porous plate of the present invention can not only effectively improve the output power of the tail gas temperature difference generator, but also bring about a small resistance pressure loss, and the net output power of the generator is high. And due to the low pressure loss, it has little effect on the normal operation of the internal combustion engine.

[0016] 3. The porous plate of the present invention can make the surface temperature distribution of the exhaust gas heat exchanger more uniform by enhancing heat transfer at local positions, and the temperature difference between the cold and hot ends of the thermoelectric modules at different positions is smaller, thereby improving the reliability of the thermoelectric generator.

[0017] 4. The present invention has universal applicability. Since the porous plate is easy to process and install, it is simple to maintain and can conveniently improve the existing tail gas temperature difference generator, thereby improving the economy and reliability of the existing generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The tail gas temperature difference generator with a porous plate of the present invention;

[0019] Figure 2 This is a schematic diagram of the installation of a tail gas heat exchanger with multiple bottom plates in Example 1 of the present invention;

[0020] Figure 3 It is a front view of the porous plate of the present invention;

[0021] Figure 4 It is a top view of the porous plate of the present invention.

[0022] Among them, 1-exhaust gas heat exchanger; 2-porous plate; 3-thermoelectric module; 4-cooling water heat exchanger; 5-perforated bottom plate. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] See attached Figure 1-4 This embodiment discloses an exhaust gas temperature difference generator with a porous plate structure, including an exhaust gas heat exchanger 1, a porous plate 2, a thermoelectric module 3 and a cooling water heat exchanger 4. The thermoelectric module 3 is installed between the exhaust gas heat exchanger 1 and the cooling water heat exchanger 4, and the three are clamped by a clamp, and thermal conductive silicone grease or graphite sheets are applied at both ends of the thermoelectric module 3 to reduce contact thermal resistance.

[0026] like Figure 2 , Figure 4 As shown, the porous plate 2 is installed in the exhaust gas heat exchanger 1. It is necessary to ensure that the porous plate 2 can fully cover the flow channel section of the exhaust gas heat exchanger 1. It can be directly welded in the exhaust gas heat exchanger 1. In this embodiment, a long groove is opened on the exhaust gas heat exchanger 1. In this embodiment, a perforated bottom plate 5 is welded to the bottom of the porous plate 2. The porous plate 2 is inserted into the exhaust gas heat exchanger 1 through the long groove, and the perforated bottom plate 5 is fixed to the exhaust gas heat exchanger 1 by the bottom plate screws, so that the porous plate 2 can be easily repaired and replaced.

[0027] The porous plate 2 of the present invention has an optimal installation position, which is related to the number of thermoelectric modules. Specifically, the thermoelectric modules 3 are arranged in n rows along the exhaust gas flow direction, and the number of porous plates is m. When the number of rows of thermoelectric modules is 2≤n≤3, the porous plate is arranged in the middle of the second row of thermoelectric modules. When the number of rows of thermoelectric modules is n≥4, the porous plate is arranged in the middle of thermoelectric modules that are multiples of 3, and m≤n. In this embodiment, a total of 5 rows of thermoelectric modules are arranged along the exhaust gas flow direction, and the optimal installation position is in the middle of the third row of thermoelectric modules. This embodiment provides the optimal installation position of the porous plate 2, and the exhaust gas temperature difference generator can obtain the maximum net output power and the most uniform temperature distribution.

[0028] like Figure 3 As shown, the holes on the porous plate 2 are arranged in an equilateral triangle, with a hole diameter of 1-5 mm, and the holes are evenly distributed on the porous plate 2. The optimal porosity is between 20% and 40%. As the porosity decreases, the output power increases while the pressure loss increases. When the porosity is between 20% and 40%, the optimal net output power can be obtained.

[0029] As a preferred embodiment of the present invention, the optimal thickness of the porous plate 2 is 1-2 mm. If the porous plate 2 is too thin, it is easy to deform under the impact of high-temperature exhaust gas. If the porous plate 2 is too thick, the cost will be increased and the resistance pressure loss will be increased. Therefore, the thickness of the plate is preferably 1-2 mm.

[0030] As a preferred embodiment of the present invention, the material of the porous plate 2 can be selected according to the exhaust gas parameters. For high-temperature exhaust gas, high-temperature resistant metal materials such as stainless steel, copper, and brass are preferred; for low-temperature exhaust gas, other cheap and strong materials can also be selected, but it is necessary to ensure that the structure is stable within the exhaust gas temperature range.

[0031] In this example, the exhaust gas heat exchanger 1 is a rectangular flow channel, but the technical solution of the present invention is also applicable to cylindrical, polygonal and other exhaust gas flow channels.

[0032] The porous plate of the present invention has a simple structure and low processing cost. The materials are easy to obtain and can be mass-produced. In addition, the number of porous plates used in the exhaust gas temperature difference generator is relatively small, which greatly reduces the process cost. The porous plate can not only effectively improve the output power of the exhaust gas temperature difference generator, but also brings about a small resistance pressure loss, and the net output power of the generator is high. The porous plate has low pressure loss and has little effect on the normal operation of the internal combustion engine. The porous plate can make the surface temperature distribution of the exhaust gas heat exchanger more uniform by enhancing heat transfer at local positions, and the difference between thermoelectric modules at different positions is smaller, thereby improving the reliability of the temperature difference generator. This method has universal applicability. Since the porous plate is easy to process and simple to install, the maintenance operation is simple and the cost is low.

[0033] Furthermore, the present invention can not only guide the design and processing of new generators, but also can conveniently transform existing temperature difference generators. The present invention is not only suitable for large and heavy vehicles and ships and other means of transportation using internal combustion engines, but can also be used for industrial waste heat recovery and power generation.

[0034] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A tail gas temperature difference generator with a porous plate structure, characterized in that: The invention comprises an exhaust gas heat exchanger (1), a porous plate (2), a thermoelectric module (3) and a cooling water heat exchanger (4); the thermoelectric module (3) is installed between the exhaust gas heat exchanger (1) and the cooling water heat exchanger (4); the porous plate (2) is arranged in the exhaust gas heat exchanger (1) and can fully cover the flow channel section of the exhaust gas heat exchanger (1); the number of the porous plates (2) is set according to the number of the thermoelectric modules (3); the thermoelectric modules (3) are arranged in n rows along the exhaust gas flow direction; the number of the porous plates (2) is m; when the number of rows of the thermoelectric modules (3) is 2≤n≤3, the porous plate (2) is arranged in the middle of the second row of thermoelectric modules (3); when the number of rows of the thermoelectric modules (3) is n≥4, the porous plate (2) is arranged in the middle of the thermoelectric modules (3) that are multiples of 3.

2. The tail gas temperature difference generator with a porous plate structure according to claim 1, characterized in that: A bottom plate with holes (5) is provided at the bottom of the porous plate (2), a long slot is provided on the exhaust gas heat exchanger (1), the porous plate (2) is inserted into the exhaust gas heat exchanger (1) through the long slot, and the bottom plate with holes (5) is fixed to the long slot of the exhaust gas heat exchanger (1) by bolts.

3. The tail gas temperature difference generator with a porous plate structure according to claim 1, characterized in that: Thermal conductive silicone grease or graphite sheets are applied to both ends of the thermoelectric module (3).

4. The tail gas temperature difference generator with a porous plate structure according to claim 1, characterized in that: The holes on the porous plate (2) are arranged in a regular triangle, and the hole diameter is 1-5 mm.

5. The tail gas temperature difference generator with a porous plate structure according to claim 1, characterized in that: The porosity of the porous plate (2) is 20%-40%.

6. The tail gas temperature difference generator with a porous plate structure according to claim 1, characterized in that: The thickness of the porous plate (2) is 1-2 mm.

7. The tail gas temperature difference generator with a porous plate structure according to claim 1, characterized in that: The porous plate (2) is made of stainless steel, copper or brass.

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