Power generation device and power generation system

Abstract

This power generation device comprises: a transport unit that transports fluid; a plurality of thermoelectric conversion units corresponding to a plurality of temperature regions in the transport unit; and a power output unit that outputs power obtained by the plurality of thermoelectric conversion units.

Description

Power Generation Device and Power Generation System

[0001] The present invention relates to a technology for generating power by utilizing exhaust heat.

[0002] Systems that generate power by utilizing exhaust heat have been conventionally proposed. In the prior art, as a method for generating power using exhaust heat, a general approach is to install one specific type of thermoelectric material in a pipe, and obtain electric power from the exhaust heat via this material.

[0003] For example, in the "thermoelectric power generation system using automobile waste heat" disclosed in Non-Patent Document 1, thermoelectric conversion materials are arranged in layers to convert the exhaust heat of relatively high-temperature exhaust gas around the catalyzer into electric power.

[0004] Research and Development for Thermoelectric Power Generation Using Waste Heat Emitted from Various Systems, Materials of the Industry-Academia Collaboration Cleantech Technology Exhibition Seminar, Nagoya Chamber of Commerce and Industry, Feb. 25, 2021, Influence of Catalyst Temperature Behavior in Cold Regions on N2O Emissions, https: / / www.ntsel.go.jp / Portals / 0 / resources / forum / 13files / 13-14p.pdf, searched on Mar. 31, Reiwa 7; New Developments in High-Efficiency Thermoelectric Power Generation Materials, IEEJ Transactions on Fundamentals and Materials, Vol. 124, No. 4, 2004, https: / / www.jstage.jst.go.jp / article / ieejfms / 124 / 4 / 124_4_303 / _pdf, searched on Mar. 31, Reiwa 7

[0005] However, in the prior art in which a thermoelectric conversion material is installed in a pipe to obtain electric power from exhaust heat via the thermoelectric conversion material, the temperature of the gas or liquid flowing through the pipe decreases as it flows downstream. As disclosed in Non-Patent Document 3, the conversion efficiency of thermoelectric conversion materials depends on temperature, so it has been difficult for the prior art to perform high-efficiency power generation throughout the entire pipe.

[0006] The present invention has been made in view of the above points, and aims to provide a technology for performing high-efficiency power generation by utilizing exhaust heat.

[0007] According to the disclosed technology, a power generation device is provided comprising: a transport unit for transporting a fluid; a plurality of thermoelectric conversion units corresponding to a plurality of temperature ranges in the transport unit; and a power output unit for outputting power obtained by the plurality of thermoelectric conversion units.

[0008] According to the disclosed technology, a technology is provided for generating electricity with high efficiency by utilizing waste heat.

[0009] This is a diagram showing an example of the configuration of a power generation system. This is a flowchart for explaining the operation of the power generation system. This is a diagram showing the flow of gas or liquid in the transport section 20 and the radiation spectrum of each region. This is a diagram showing the TPV (Thermophotovoltaic) panel corresponding to the thermoelectric conversion section 40, and the converters corresponding to the control section 50 and the voltage conversion section 60. This is a graph showing Wien's displacement law. This is a diagram showing an example of the arrangement of piping and TPV panels. This is a diagram showing an example using a heat storage device. This is a diagram showing an example of the hardware configuration of the device.

[0010] Hereinafter, embodiments of the present invention (this embodiment) will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the embodiments described below.

[0011] The following will first describe the conventional technology and its problems in more detail, and then describe the technology according to this embodiment in detail. Note that gases and liquids may be collectively referred to as fluids. In other words, a "fluid" may be a gas or a liquid. Furthermore, a "fluid" may be a flowing substance that is neither a gas nor a liquid. In this embodiment, a gas or a liquid is used as the heat medium, but a flowing substance that is neither a gas nor a liquid may also be used as the heat medium.

[0012] (Outline of the Embodiment) As mentioned above, in conventional technology that obtains electricity from waste heat via thermoelectric conversion materials, it is difficult to generate electricity efficiently throughout the entire pipe because the temperature of the gas or liquid flowing through the pipe decreases as it goes downstream.

[0013] Therefore, in this embodiment, in order to solve the above problems, power generation is performed with high efficiency by using the optimal thermoelectric conversion material according to the temperature of the gas or liquid flowing through the pipe.

[0014] The configuration and operation of the system in this embodiment will be described in detail below.

[0015] (System Configuration) Figure 1 shows an example of the configuration of the power generation system in this embodiment. As shown in Figure 1, this power generation system comprises a heat generation unit 10, a transport unit 20, a discharge unit 31, a cooling unit 32, a thermoelectric conversion unit 40, a control unit 50, a voltage conversion unit 60, a power output unit 70, a measurement unit 81, a data storage unit 83, an input unit 82, a calculation unit 85, an output unit 86, and an overall control unit 84.

[0016] Furthermore, a configuration comprising a transport unit 20, a thermoelectric conversion unit 40, and a power output unit 70 may also be called a power generation device.

[0017] Furthermore, the heat-generating unit 10, transport unit 20, discharge unit 31, cooling unit 32, thermoelectric conversion unit 40, control unit 50, voltage conversion unit 60, and power output unit 70 may each be a separate device. If these are separate devices, the heat-generating unit 10, transport unit 20, discharge unit 31, cooling unit 32, thermoelectric conversion unit 40, control unit 50, voltage conversion unit 60, and power output unit 70 may be referred to as the heat-generating device 10, transport device 20, discharge device 31, cooling device 32, thermoelectric conversion device 40, control device 50, voltage conversion device 60, and power output device 70.

[0018] Furthermore, a configuration comprising a transport device 20, a thermoelectric converter 40, and a power output device 70 may also be called a power generation system.

[0019] In this embodiment, the configuration shown in Figure 1 is referred to as the power generation system. The power generation system in this embodiment utilizes the characteristic that there is a temperature gradient in the transport section 20, which corresponds to piping. The transport section 20 is divided into temperature regions, and thermoelectric conversion sections 40 having optimal (highly efficient) characteristics for each temperature region are arranged around the transport section 20. Highly efficient power output is achieved by adjusting the control section 50 and the voltage conversion section 60 based on the output characteristics of the thermoelectric conversion section 40.

[0020] This section explains the function of each component of the power generation system.

[0021] The heat-generating unit 10 sends heated gas or liquid to the transport unit 20. The transport unit 20 is a pipe or loop pipe that transports heated gas or liquid from the heat-generating unit 10 to the discharge unit 31 or the cooling unit 32. As shown in Figure 1, the temperature range is divided into (a) to (c) in order from high temperature to low temperature. Note that having three divisions as shown in Figure 1 is just one example. The number of divisions may be two, or four or more.

[0022] The discharge unit 31 discharges the gas or liquid sent from the transport unit 20 to the outside. The cooling unit 32 cools the gas or liquid sent from the transport unit 20. If the transport unit 20 is a loop pipe, the cooling unit 32 may be used to cool the gas or liquid and return the cooled gas or liquid to the transport unit 20. If the transport unit 20 is not a loop pipe, the heat dissipation unit 31 discharges the gas or liquid to the outside.

[0023] The thermoelectric conversion unit 40 converts heat into electricity (power) using a thermoelectric conversion material. Different thermoelectric conversion materials are used for the high-temperature region (a), the medium-temperature region (b), and the low-temperature region (c), with materials specialized for low temperatures being installed further downstream. In other words, each thermoelectric conversion unit 40 in the multiple thermoelectric conversion units 40 is configured such that the thermoelectric conversion efficiency in its corresponding temperature region is higher than the thermoelectric conversion efficiency in other temperature regions.

[0024] In Figure 1, the thermoelectric conversion unit 40 corresponding to the high-temperature region (a) is labeled (a), the thermoelectric conversion unit 40 corresponding to the medium-temperature region (b) is labeled (b), and the thermoelectric conversion unit 40 corresponding to the low-temperature region (c) is labeled (c). The same applies to the control unit 50 and the voltage conversion unit 60, which will be described later.

[0025] Note that the number of temperature regions (number of divisions) in the transport unit 20 does not have to be the same as the number of thermoelectric conversion units 40. Alternatively, the region in the transport unit 20 where one thermoelectric conversion unit 40 is located may be considered as one temperature region.

[0026] The control unit 50 controls the voltage conversion unit 60 so that it operates with high efficiency. For example, it performs maximum power point tracking (MPPT) control individually for each temperature range. The control unit 50 may be included in the overall control unit 84.

[0027] The voltage conversion unit 60 operates to maintain a constant output voltage while making the input voltage variable (MPPT control). The voltage conversion unit 60 performs optimal control individually for each of (a) to (c). The power output unit 70 combines the outputs from each voltage conversion unit 60 and outputs power as a whole.

[0028] The measuring unit measures the output voltage and current of the thermoelectric conversion unit 40 and the voltage conversion unit 60 in 81, (a) to (c).

[0029] The data storage unit 83 stores the information acquired by the measurement unit 81 in chronological order and updates it as needed. The data storage unit 83 also deletes information. The input unit 82 inputs the specifications and setting information of each part of the power generation system and stores it in the data storage unit 83.

[0030] The calculation unit 85 calculates the conversion efficiency and power from the measurement data. The output unit 86 outputs the calculation results or saved data.

[0031] The overall control unit 84 adjusts the parameters of each control unit 50 and each voltage conversion unit 60 based on the results of the calculation unit 85, thereby improving efficiency in real time. For example, by sending control signals to a DC / DC converter (corresponding to the control unit 50 and voltage conversion unit 60) that utilizes a programmable gate driver IC, the efficiency of the control unit 50 and voltage conversion unit 60 can be improved in real time.

[0032] Furthermore, the following effects can be obtained with the system configuration shown in Figure 1.

[0033] - Improved efficiency during system upgrades ⇒ Based on the time-series voltage and current data of each thermoelectric conversion unit 40 obtained by the measurement unit 81, the degree of deterioration of each thermoelectric conversion unit 40 and the suitability of each thermoelectric conversion unit 40 for each temperature range can be analyzed and used for redesign during system upgrades.

[0034] - Reduction of downtime through fault prediction ⇒ By detecting significant (e.g., 50% or more) decreases in conversion efficiency and power from time-series data obtained by the measurement unit 81 and the calculation unit 85, and predicting the location of the fault, downtime can be reduced.

[0035] (Examples of waste heat / power generation section) In this embodiment, the waste heat obtained from the heat generation section 10 used for power generation is not limited to waste heat from a specific field or device, but can be any type of waste heat. Examples of waste heat (or heat generation section) used for power generation are as follows.

[0036] - Waste heat from factory boilers - Waste heat from automobiles or ships - Combustion heat from gas burners - Steel mill slabs - Concentrated sunlight - Nuclear fusion reactors - Nuclear power generation - Thermal power generation (Example of operation) An example of the operation of the power generation system in this embodiment will be explained with reference to the flowchart in Figure 2. Here, it is assumed that the temperature range of the transport unit 20 is divided into three or more sections, from the high-temperature region (a) on the side closer to the heat-generating unit 10 to the low-temperature region (n) on the side farther from the heat-generating unit 10.

[0037] In step 1 (S1), the heat-generating unit 10 begins transporting gas or liquid. In step 2 (S2), the transport unit 20 causes the gas or liquid to reach the high-temperature region (a). The gas or liquid then moves sequentially to the region beyond the high-temperature region (a), reaching the low-temperature region (n) in step 6 (S6).

[0038] Regarding the processing when a gas or liquid reaches a high-temperature region (a), in S3, the thermoelectric conversion unit 40(a) converts the thermal radiation from the high-temperature region of the transport unit 20 into electricity. In S4, the control unit 50(a) outputs maximum power through MPPT control. In S5, the voltage conversion unit 60(a) converts the input voltage into a constant voltage.

[0039] In each region, the same processing as in S3 to S5 is performed. In S13, the power output unit 70 outputs the sum of the output powers of the voltage conversion units (a) to (n).

[0040] When the transport unit 20 is a loop pipe (Yes in S10), the gas or liquid is cooled by the cooling unit 32 in S11, and the cooled gas or liquid is returned to the high-temperature region (a) of the transport unit 20. When the transport unit 20 is not a loop pipe (No in S10), the gas or liquid is discharged by the discharge unit 31 in S12.

[0041] (Example) A more specific configuration example of the power generation system according to the present embodiment will be described as an example.

[0042] FIG. 3 is a diagram showing the flow of gas or liquid in the transport unit 20 of the present example, and the radiation spectrum of each region. FIG. 4 is a diagram showing a TPV (Thermophotovoltaic) panel corresponding to the thermoelectric conversion unit 40, and a converter corresponding to the control unit 50 and the voltage conversion unit 60.

[0043] As shown in FIG. 3, in the present example, the pipe that is the transport unit 20 is divided into temperature regions (a) to (c). As shown in FIG. 4, a TPV panel as a thermoelectric conversion material that is optimal (highly efficient) for each temperature region is used.

[0044] The use of TVP (thermophotovoltaic) as a thermoelectric conversion material for performing highly efficient thermoelectric power generation is merely an example. For example, a thermoelectric conversion element based on the Seebeck effect may be used as the thermoelectric conversion material for performing highly efficient thermoelectric power generation. Further, the TPV panel in the present example may be in any of the forms of "array, string, module, and cell" of TPV.

[0045] A device that performs thermo-photovoltaic (TPV) power generation is a device that converts infrared rays of thermal radiation into electric power. Its principle is, similar to solar power generation, to irradiate a cell with infrared photons and convert the generated potential into electric power.

[0046] The peak positions are indicated by thick dotted lines for each of the radiation spectra (a) to (c) shown in FIG. 3. The hatched portion in each of the radiation spectra (a) to (c) represents a wavelength region where the conversion efficiency of each TPV panel is 60% or more.

[0047] FIG. 5 is a graph showing Wien's displacement law disclosed on the homepage of the Astronomical Dictionary (https: / / astro-dic.jp / wiens-displacement-law / ). As shown in FIG. 3, according to Wien's displacement law, the peak of radiation intensity shifts to the longer wavelength side as the temperature decreases. Each TPV panel shown in FIG. 4 is configured to be highly efficient for the corresponding radiation spectrum.

[0048] That is, since the peak of the radiation spectrum shifts to the longer wavelength side toward the downstream of the piping, as the TPV panels shown in FIG. 4, those specialized for lower temperatures (TPV panels with smaller band gaps) are used as they go downstream in the transport unit 20.

[0049] The TPV panel (a) shown in FIG. 4 has sensitivity only in the wavelength region indicated by the hatched square in the radiation spectrum (a) of FIG. 3, and can convert thermal radiation in that wavelength region into electric power. The TPV panel (b) shown in FIG. 4 has sensitivity only in the wavelength region indicated by the hatched square in the radiation spectrum (b) of FIG. 3, and can convert thermal radiation in that wavelength region into electric power. The TPV panel (c) shown in FIG. 4 has sensitivity only in the wavelength region indicated by the hatched square in the radiation spectrum (c) of FIG. 3, and can convert thermal radiation in that wavelength region into electric power.

[0050] In addition, for higher efficiency, a mirror may be installed on the back surface of the TPV panel to reflect photons that have passed through without being converted into electric power by the TPV panel.

[0051] Each of the converters (a) to (c) shown in FIG. 4 performs MPPT control on the output power of the connected TPV panel, and outputs the power with the output voltage kept constant.

[0052] FIG. 6 shows two arrangement examples (left side and right side) as examples of arrangement of piping and TPV panels. In each example, the TPV panels are arranged around the piping, and installed with the heat absorption surfaces of the TPV panels facing the piping side. Various shapes such as a cylinder or a rectangular cuboid can be used as the shape of the piping.

[0053] Furthermore, as shown in Figure 7, a configuration may be used in which heat storage devices with different shapes from the piping are installed for each temperature range, and the heat storage devices are connected by piping. In the example in Figure 7, TPV panels are arranged around each heat storage device. In the example in Figure 7, the shape of the heat storage device is cylindrical, but the shape of the heat storage device is not limited to a cylinder. For example, the shape of the heat storage device may be spherical.

[0054] (Example Hardware Configuration) The device described in this embodiment as the control unit 50, and the device having "data storage unit 83, input unit 82, calculation unit 85, output unit 86, and overall control unit 84", can be realized, for example, by having a computer execute a program. This computer may be a physical computer or a virtual machine on the cloud.

[0055] In other words, the device can be realized by using hardware resources such as the CPU and memory built into a computer to execute a program corresponding to the processing performed by the device. The program can be recorded on a computer-readable recording medium (such as portable memory), saved, and distributed. It can also be provided via a network, such as the Internet or email.

[0056] Figure 8 shows an example of the hardware configuration of the computer described above. The computer in Figure 8 has a drive device 1000, an auxiliary storage device 1002, a memory device 1003, a CPU 1004, an interface device 1005, a display device 1006, an input device 1007, an output device 1008, etc., all of which are interconnected by bus B. The computer may also be equipped with a GPU.

[0057] The program that enables processing on the computer is provided on a recording medium 1001, such as a CD-ROM or memory card. When the recording medium 1001 containing the program is set in the drive device 1000, the program is installed from the recording medium 1001 to the auxiliary storage device 1002 via the drive device 1000. However, the program does not necessarily have to be installed from the recording medium 1001; it may also be downloaded from another computer via a network. The auxiliary storage device 1002 stores the installed program as well as necessary files and data.

[0058] The memory device 1003 reads and stores a program from the auxiliary storage device 1002 when a program startup command is received. The CPU 1004 implements the functions related to the memory device 1003 according to the program stored in the memory device 1003. The interface device 1005 is used as an interface for connecting to a network, etc. The display device 1006 displays a GUI (Graphical User Interface) etc., based on a program. The input device 1007 consists of a keyboard and mouse, buttons, or a touch panel, etc., and is used to input various operation commands. The output device 1008 outputs the calculation results.

[0059] Furthermore, the functions of the elements disclosed herein may be implemented using circuits or processing circuitry that include general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), conventional circuits, and / or combinations thereof that are programmed using one or more programs stored in one or more memories, or otherwise configured to perform the disclosed functions. A processor is considered processing circuitry or circuitry because it includes transistors and other circuits. A processor may be a programmed processor that executes programs stored in memory. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. Hardware may be any hardware disclosed herein that is programmed or configured to perform the enumerated functions.

[0060] The system includes memory for storing a computer program containing computer instructions. These computer instructions provide logic and routines that enable hardware (e.g., processing circuitry or circuitry) to perform the methods disclosed herein. The computer program can be implemented in commonly known forms, such as computer-readable storage media, computer program products, memory devices, recording media such as CD-ROMs and DVDs, and / or memory in FPGAs and ASICs.

[0061] (Effects of the technology according to the embodiment) With the technology according to this embodiment, the optimal thermoelectric conversion material is used according to the temperature of the gas or liquid flowing through the transport unit 20, so that power can be generated with high efficiency throughout the entire transport unit 20.

[0062] The following additional information is disclosed regarding the embodiments described above.

[0063] <Notes> (Note 1) A power generation device comprising: a transport unit for transporting a fluid; a plurality of thermoelectric conversion units corresponding to a plurality of temperature regions in the transport unit; and a power output unit for outputting power obtained by the plurality of thermoelectric conversion units. (Note 2) The power generation device according to Note 1, wherein each thermoelectric conversion unit in the plurality of thermoelectric conversion units is configured such that the thermoelectric conversion efficiency in the corresponding temperature region is higher than the thermoelectric conversion efficiency in other temperature regions. (Note 3) The power generation device according to Note 2, wherein each thermoelectric conversion unit in the plurality of thermoelectric conversion units is configured to be sensitive only to a specific wavelength region in the radiation spectrum of the corresponding temperature region. (Note 4) The power generation device according to Note 1, wherein the fluid is sent from a heat-generating unit to the transport unit, and the plurality of temperature regions are arranged such that the temperature decreases from the side closer to the heat-generating unit toward the side further away from the heat-generating unit. (Note 5) The power generation device according to Note 1, wherein the transport section is a pipe, and each thermoelectric conversion section in the plurality of thermoelectric conversion sections is arranged around the pipe in the corresponding temperature range. (Note 6) The power generation device according to Note 1, wherein the transport section has a pipe and a heat storage device, and each thermoelectric conversion section in the plurality of thermoelectric conversion sections is arranged around the heat storage device in the corresponding temperature range. (Note 7) A power generation system comprising: a transport device for transporting a heated fluid; a plurality of thermoelectric conversion devices corresponding to a plurality of temperature ranges in the transport device; and a power output device for outputting power obtained by the plurality of thermoelectric conversion devices.

[0064] Although this embodiment has been described above, the present invention is not limited to this specific embodiment, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims.

[0065] 10 Heating section 20 Transport section 31 Discharge section 32 Cooling section 40 Thermoelectric conversion section 50 Control section 60 Voltage conversion section 70 Power output section 81 Measurement section 82 Input section 83 Data storage section 84 Overall control section 85 Calculation section 86 Output section 1000 Drive device 1001 Recording medium 1002 Auxiliary storage device 1003 Memory device 1004 CPU 1005 Interface device 1006 Display device 1007 Input device 1008 Output device

Claims

1. A power generation device comprising: a transport unit for transporting a fluid; a plurality of thermoelectric conversion units corresponding to a plurality of temperature ranges in the transport unit; and a power output unit for outputting power obtained by the plurality of thermoelectric conversion units.

2. The power generation device according to claim 1, wherein each thermoelectric conversion unit in the plurality of thermoelectric conversion units is configured such that the thermoelectric conversion efficiency in a corresponding temperature range is higher than the thermoelectric conversion efficiency in other temperature ranges.

3. The power generation device according to claim 2, wherein each of the plurality of thermoelectric conversion units is configured to be sensitive only to a specific wavelength region in the radiation spectrum of the corresponding temperature region.

4. The power generation device according to claim 1, wherein the fluid is sent from the heat-generating section to the transport section, and the plurality of temperature regions are arranged such that the temperature decreases from the side closer to the heat-generating section toward the side further away from the heat-generating section.

5. The power generation device according to claim 1, wherein the transport section is a pipe, and each of the plurality of thermoelectric conversion sections is arranged around the pipe in the corresponding temperature range.

6. The power generation apparatus according to claim 1, wherein the transport unit comprises piping and a heat storage device, and each of the plurality of thermoelectric conversion units is arranged around the heat storage device in the corresponding temperature range.

7. A power generation system comprising: a transport device for transporting a heated fluid; a plurality of thermoelectric converters corresponding to a plurality of temperature ranges in the transport device; and a power output device for outputting power obtained by the plurality of thermoelectric converters.

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