Cylindrical exhaust thermo-electric generator with integrated diffuser assembly for ship's waste heat recovery

Abstract

Disclosed herein an Exhaust Thermo-Electric Generator (ETEG) comprising: a cylindrical heat recovery unit having multiple slots in multiple curved fins placed radially for providing hot surface for thermoelectric modules; said curved fins being 'T' shaped and having a curved profile at the matching outer edge of the cylinder and top surface of said curved fins being flat adapted to accommodate said thermoelectric modules; wherein the fins are provided with multiple slots to enhance surface area for heat exchange and the curvature of the slots matches the inner edge of the cylinder providing uniform symmetric flow for exhaust gases; and wherein a diffuser cone with swirl fin placed along the center of cylindrical unit for increasing the flow turbulence and residence time of exhaust within the body of the unit capable of motion in axial direction in order to handle dynamic exhaust condition.

Description

[0001] CYLINDRICAL EXHAUST THERMO-ELECTRIC GENERATOR WITH INTEGRATED DIFFUSER ASSEMBLY FOR SHIP’S WASTE HEAT RECOVERY

[0002] FIELD OF INVENTION

[0003] The current invention related to cylindrical Exhaust Thermo-Electric Generator (ETEG) with Integrated Diffuser Assembly for Ship’s Waste Heat Recovery as a Replacement of Exhaust Coolers.

[0004] BACKGROUND OF INVENTION

[0005] Importance of thermoelectric waste heat recovery system as an effective step in the direction of energy conservation and green technology has been realized in the recent times. The internal combustion engines remain largely inefficient while rejecting close to 40% of heat in the engine exhaust. Maritime transportation is the major transportation mode for international marine transport of goods. It is responsible for approximately 90% of world trade by volume and more than 80% of world trade is carried by sea in terms of weight. One of the most significant sources of air pollution is ship -generated emission which causes climate change. In near future, more stringent rules on emission norms are also expected. Main propulsion units, Power generation units and Incinerators are major source of greenhouse gas emissions in the marine environment. These sources of exhaust increase the heat signature of ships and hence making them visible in thermal domain. The exhaust temperatures achieved in these equipment are sufficient to achieve desired hot side temperature of Thermoelectric Modules (TEMs). Additionally, sea water is an abundant source and can be used to maintain the cold side temperature of TEMs. Therefore, the motivation for extracting energy from waste heat is twofold; one is increasing the overall efficiency of burnt fuel and second is reducing the heat signature of a ship. However, application of ETEG on large engines have been limited to lower efficiency of TE modules and the fact that design of exhaust TEG fact that all exhaust ducts are cylindrical, thus, installation of TE modules which are inherently flat is specifically challenging. In WO2014157287A1, the inventor described exhaust filter device that collects particulate matter in the exhaust gas, and a thermoelectric power generator for an internal combustion engine such as a diesel engine mounted on a ship. The pipe is formed in a polygonal cross section, the thermoelectric unit group is attached to each plane portion of the pipe, and the heat collecting fins are protruded in the pipe.

[0006] In CN107939624B, the inventor combines solar trough with thermoelectric and organic Rankine cycle for ship waste heat utilization. However, the described exhaust TEG remained flat plate type.

[0007] In CN107612426A, the inventors proposed a design of two-stage thermoelectric power generation device for ship waste heat recovery and a power generation method for exhaust temperatures of about 500 °C. However, the model uses hexahedron topology with two layers of TE modules.

[0008] In CN107359827B, the inventors have modelled selective catalytic reduction (SCR) with exhaust TEG. The overall design is cylindrical wherein the exhaust tanks (hot side) and water tanks (cold side) are radially arranged around the perforated exhaust duct. The TE modules are sandwiched radially between the tanks. In this design exhaust flow is diverted radially outward and heat is absorbed in exhaust tanks filled with heat absorbing material.

[0009] In CN105790638A, the inventor uses a hexagonal topology-based exhaust TEG which uses phase change material for hot side. The proposed modular exhaust TEG can be connected in series.

[0010] In CN104935210A, the inventor has used cylindrical topology, however, the hotside heat exchanger consist of a duct with honeycomb structure. A heat transfer medium flows through the helical channels inside the hotside heat exchanger passing the heat to the TE modules. The duct has square slots in with TE modules are placed and annular cooled plate fitted tightly above it. The honeycomb structure in the said patent would have higher pressure drops, thus, cannot be used on heavy diesel engines

[0011] In CN102549789A, a thermoelectric-based power generation systems and methods are proposed. A cylindrical topology wherein two concentric cylinders are used. The inner cylinder is installed with a bypass valve to regulate the flow and back pressure. The other novelty is a proposed TE element design which can be used on hot and cold pathways. The design is capable of handling dynamic exhaust condition and thermal stresses.

[0012] In CN108832848A, the inventors have proposed a TEG with annular for low temperature waste heat waste heat recovery. The inventor uses annular framework (ring Skelton) forming slots in which multiple heat exchangers (material - foam aluminium) which is evenly distributed circumferentially on which TE modules are mounted. The water blocks arranged circumferentially over the TE modules forms the cold side heat exchanger.

[0013] In RU217290U1, the inventor proposed a technology related to shipbuilding, specifically focusing on the design and operation of a thermoelectric generator (TEG) for converting thermal energy into electrical energy in ship power plants (SPP). The design is unified to work with both gaseous and liquid media as heat sources, recovering waste heat from different parts of the ship's power plant. The existing setup has a polygon structure (rectangular gas chamber to be specific) and uses gas manifolds and fairings to manage the flow of gaseous hot medium (exhaust gases).

[0014] In RU171447U1, the inventor proposed a TEG hot heat exchanger with variable geometry, featuring a cross-sectional shape resembling a polyhedron. The heat exchanger design encompasses movable rotary ribs installed on its faces which can be rotated which is used to regulate the temperature distribution inside heat exchanger. The design uses rotary ribs for temperature regulation.

[0015] In KR20210054218A, the inventor has proposed a multi-layer thermoelectric generator for recycling industrial waste heat. The generator consists of multiple hexahedron unit module. Each module has internal fins, oriented towards center. The invention introduces the idea of varying the stacking angles of neighbouring unit thermoelectric modules.

[0016] In KR101860600B1, the technology involves a device consisting of a hexagonal housing that forms an internal cylindrical space as hot side heat exchanger. The hexagonal housings are in two detachable parts and devoid of fins. The TE modules are arranged on the hexagonal housing and the outer plate having external fins forms the cold side heat exchanger. The novelty of the invention lies in detachable design which makes it feasible to clamp on circular exhaust ducts without cutting the pipe.

[0017] In JP6096562B2, the inventor has proposed a thermoelectric generator system designed for use in ships to convert waste heat from internal combustion engines. The device consists of a cylindrical duct matching the external profile of the exhaust duct of the engine. However, the internal passage is a square passage. The thermoelectric units are attached to a pipe with a polygonal cross-section, allowing them to be densely arranged for improved heat collection efficiency.

[0018] In JP4923997B2, a hexagonal thermoelectric generator is designed to recover energy from exhaust heat, such as from exhaust gas emitted by an engine. These heat recovery units consist of internal fins and fin top plates that are positioned within the exhaust pipe. The fins collect heat from the exhaust gas. The primary objective of the design is to mitigate the stress related issues in the device due to thermal expansion. In CN208939848U describes a heat recovery device from an engine. The device described consist of cylinder with a flat top. a base plate (Hot side Heat exchanger) is mounted on the circumference of the cylinder (gas chamber) and acts as a housing for mounting the TE modules. The TE modules are arranged vertically heat exchanger mounted on the cold end of the TE modules. A copper plate is used for mounting of cold side heat exchanger (with fins) and also to enhance the heat transfer.

[0019] Therefore, there remain a need for Exhaust Thermo-Electric Generator (ETEG) that can be directly installed on the cylindrical exhaust ducts solving the difficulty of installation of flat TE modules on curved surface by innovative design while maintaining the cylindrical exhaust flow. Further, there is a need for an effective replacement for the sea water cooled exhaust coolers which are currently installed on marine engines to reduce exhaust gas temperatures.

[0020] SUMMARY OF INVENTION

[0021] The objective of present invention is to overcome the drawbacks of related arts.

[0022] Further, objective of present invention is to provide an Exhaust Thermo-Electric Generator (ETEG) that can be directly installed on the cylindrical exhaust ducts solving the difficulty of installation of flat TE modules on curved surface by innovative design while maintaining the cylindrical flow of exhaust gases.

[0023] Another objective of present invention is to provide an effective replacement for the sea water cooled exhaust coolers which are currently installed on marine engines for reduction of the exhaust gas temperature.

[0024] Further objective of present invention is to provide to ensure uniform cylindrical flow for exhaust gases maximising efficiency and minimising pressure drop. According to one aspect of present invention, there is provided an Exhaust Thermo-Electric Generator (ETEG) comprising: a cylindrical heat recovery unit having multiple slots in which multiple curved fins placed radially for providing hot surface for thermoelectric modules; said curved fins being ‘T’ shaped and having a curved profile at the matching outer edge of the cylinder and top surface of said curved fins being flat adapted to accommodate said thermoelectric modules; wherein the fins are provided with multiple slots to enhance surface area for heat exchange and the curvature of the slots matches the inner edge of the cylinder providing uniform symmetric flow for exhaust gases; and wherein a diffuser cone with swirl fin placed along the center of cylindrical unit capable of axial movement for increasing the flow turbulence and residence time of exhaust within the body of the unit.

[0025] Further, the ETEG of the present invention is capable of handling dynamic exhaust condition.

[0026] In the present invention, Cylindrical Exhaust Thermo-Electric Generator (ETEG) with Integrated Diffuser Assembly can be directly installed on the cylindrical exhaust ducts solving the difficulty of installation of flat TE modules on curved surface by innovative design while maintaining the cylindrical flow. The ETEG is designed to ensure uniform cylindrical maximising efficiency and minimising pressure drop. The proposed invention is an effective replacement for the sea water cooled exhaust coolers which are currently installed on marine engines to reduce exhaust gas temperatures. The multi-row cylindrical ETEG uses a pure cylindrical design for hot side heat exchanger maintains the flow characteristics of engine exhaust by avoiding conversion of flow to transverse or polygon. This ensures thermal uniformity among the TE modules and minimize pressure drop which is an important design criterion for ETEGs. Thermal uniformity becomes an important parameter as thermal uniformity leads to uniform internal resistances of TE modules making it easier to match external load for better power output. The present invention solves the difficulty of installation of flat TE modules on curved surface by innovative design while maintaining the cylindrical flow.

[0027] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0028] The present invention may be better understood by considering the following descriptions of the embodiments and linking them with the accompanying figures. The figures are intended to be illustrative and shall not be considered limiting to the scope of the present invention, although the present disclosure shall be considered to be within the spirit of the invention.

[0029] FIG. 1 illustrates complete cylindrical exhaust TEG according to present invention.

[0030] FIG. 2 illustrates a sub-component ‘cylindrical assembly’ according to present invention.

[0031] FIG. 3 illustrates a sub-component ‘curved fins’ according to present invention.

[0032] FIG. 4 illustrates cylindrical assembly with integrated swirler fin according to present invention.

[0033] DETAIL DESCRIPTION OF THE INVENTION

[0034] The present invention may be embodied in several forms, and the details of embodiments of the present invention will be described in the following content with figures. The embodiments described below with reference to the drawings are merely illustrative of the technical solutions of the present disclosure but are not to be constructed as limited to the technical solutions of the present disclosure.

[0035] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims. As used in the description of the invention and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0036] The present invention lies in an Exhaust Thermo-Electric Generator (ETEG) as indicated in figure 1, comprising: a cylindrical body 1 as shown in figure 2 having multiple slots 11 in which multiple curved fins 2 are placed radially for providing hot surface for thermoelectric modules 3; said curved fins as shown in figure 3 being ‘T’ shaped and having a curved profde 22 at the matching outer edge 13 of the cylinder and fat top surface 21 for accommodating plurality of thermoelectric modules units 3; wherein the fins are provided with multiple slots 23 to enhance surface area for heat exchange and the curvature 24 of the slots matches the inner edge 12 of the cylinder providing uniform symmetric flow for exhaust gases; the fin underneath is given overhang 25 to cover the slot completely in order to prevent exhaust from escaping the cylinder and wherein heat exchanger blocks 4 of dimension matching the surface area of TE module forms the cold side. The heat exchanger block has internal fins arranged with spacing in-between forming internal flow channels for heat removal. In practical application, the heat exchangers are connected in parallel flow circuit with ship’s seawater system used for exhaust cooling system. wherein the clamping mechanism 7 for each Fin-TE module-Cold side heat exchanger aggregate provides sufficient clamping force to provide requisite contact pressure for TE module sandwiched between Fin and Cold side heat exchanger. wherein a diffuser cone 51 with swirl fin 52 is placed along the centre of cylindrical body for increasing the flow turbulence and residence time of exhaust within the body of the unit. The assembly is supported with web 53 at an outlet of the cylinder and the axial movement of said swirl fin is enabled via a rack and pinion arrangement 54.

[0037] In an embodiment, said multiple slots are positioned forming rows of slots whereby each row is offset radially by 45° from the adjacent row.

[0038] In a further embodiment, the system consists of at least four fins in each row mounted radially at 900interval.

[0039] In another embodiment, said diffuser cone with swirl fin is kept in the center in the radial gap between the fins.

[0040] In yet another embodiment, said curved fins are primarily made of aluminum.

[0041] In a further embodiment, the radially opposite fins are provided with gap for free passage of exhaust and accommodate a diffuser with swirl fins designed for motion in axial direction through a rack and pinion arrangement.

[0042] In another embodiment, the individual TE modules are clamped with plurality of heat exchangers made of copper as cold side heat exchanger for TE modules.

[0043] In another embodiment, the heat extraction from the cold side heat exchanger is undertaken by the sea water flow.

[0044] In an optional embodiment, a diverging cylindrical adapter is attached at the inlet while a converging cylindrical adapter is placed at the outlet of the Cylindrical ETEG in order to connect the engine exhaust pipe to the ETEG device.

[0045] The entire device is designed to replace the exhaust coolers fitted on board ships marine engines wherein the exhaust is cooled by seawater.

Claims

CLAIMS:

1. An Exhaust Thermo-Electric Generator (ETEG) which can be directly installed on the exhaust pipe of an engine comprising: a cylindrical body having multiple slots in which multiple curved fins placed radially for providing hot surface for thermoelectric modules; said curved fins being ‘T’ shaped and having a curved profile at the matching outer edge of the cylinder and fat top surface for accommodating said thermoelectric modules; wherein the fins are provided with multiple slots to enhance surface area for heat exchange and the curvature of the slots matches the inner edge of the cylinder providing uniform symmetric flow for exhaust gases; and wherein a diffuser cone with swirl fin movable in axial direction through a rack and pinion arrangement, placed along the centre of cylindrical body for increasing the flow turbulence and residence time of exhaust within the body of the unit.

2. The ETEG as claimed in claim 1, wherein said multiple slots are positioned forming rows whereby each of the rows of slots having optimized offset angle based on the number of rows of slots.

3. The ETEG as claimed in claim 2, wherein the offset angle between adjacent rows is 45° interval, said offset angle being optimized based on the number rows required.

4. The ETEG as claimed in claim 1, comprising at least four fins in each row mounted radially at 900interval.

5. The ETEG as claimed in claim 4, wherein the number of fins in each row is optimized based on available exhaust pipe diameter.

6. The ETEG as claimed in claim 1, wherein said diffuser cone with swirl fin is kept in the center in the radial gap between the fins.

7. The ETEG as claimed in claim 6, wherein said swirl fin is supported with web support at an outlet of the cylinder and the axial movement of said swirl fin is enabled via a rack and pinion arrangement.

8. The ETEG as claimed in claim 1, wherein said curved fins are primarily made of aluminum.

9. The ETEG as claimed in claim 1, wherein the fin underneath is given overhang to cover the slot completely in order to prevent exhaust from escaping the cylinder.

10. The ETEG as claimed in claim 1, wherein the radially opposite fins are provided with gap for free passage of exhaust and accommodate a diffuser with swirl fins.

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