A solid-state thermoelectric power generation system for urban heat pipe network temperature difference power generation and an energy scheduling control method

Abstract

The application discloses a kind of urban heat pipe network temperature difference power generation solid-state thermoelectric power generation system and energy scheduling control method.The system includes: heat capture module (heat pipe uniform temperature plate+flexible heat conduction layer), cascade thermoelectric conversion module (low-temperature section bismuth telluride-based, high-temperature section skutterudite-based p / n thermoelectric pile), heat management module (liquid cooling plate+phase change material), power electronic module (MPPT+inverter), energy storage module, edge control module and cloud platform.The lowest working temperature difference ΔT of the application is ≥10℃, conversion efficiency is ≥5.4% when ΔT=90℃ (Th120 / Tc30), heat recovery rate is ≥85%, design life is ≥20 years, suitable for low-grade heat energy scene such as urban heat pipe network, and overall energy efficiency is improved through cloud collaborative scheduling.

Description

Technical Field

[0001] This invention relates to the field of urban heat pipeline network recovery and solid-state power generation technology, specifically to an urban heat pipeline network solid-state thermoelectric power generation system and energy dispatch control method based on cascaded thermopile and heat pipe-liquid cooling composite thermal management, and equipped with cloud-based intelligent scheduling. Background Technology

[0002] The return water temperature of the primary network of urban centralized heating is about 70–130℃, containing a huge amount of low-grade heat energy; traditional heating only transmits heat and does not convert the temperature difference of the pipeline into electrical energy, and the cold source of the environment in winter is wasted.

[0003] Existing semiconductor thermoelectric power generation (TEG) technologies have the following shortcomings:

[0004] The material has high thermal conductivity, limited ZT value, low conversion efficiency (approximately 5–9%), and poor adaptability over a wide temperature range.

[0005] Unstable cold-end temperature control and uneven temperature at the heat source contact surface lead to large temperature fluctuations and unstable output.

[0006] Traditional inverters are inefficient under low voltage and high current conditions and lack system-level energy dispatch and remote operation and maintenance methods.

[0007] Therefore, there is an urgent need for a solid-state thermal power generation system that can operate stably under low-grade, fluctuating heat sources and has modular and intelligent scheduling capabilities. Summary of the Invention

[0008] Purpose of the invention

[0009] This invention aims to break through the dependence of traditional TEG on high temperature difference and provide a solid-state thermal power generation system and control method for urban heating networks that can generate electricity efficiently and stably under the low-grade heat source of primary network return water (PN25) at 70~130℃, and can be modularly expanded and uniformly scheduled by a cloud platform.

[0010] Technical solution

[0011] The system of this invention includes: a heat capture module, a cascaded thermoelectric conversion module, a thermal management module, a power electronics module, an energy storage module, an edge control module, and a cloud platform. The modules are connected sequentially according to energy flow and data flow (see claim 1 for details). Figure 1 ).

[0012] Beneficial effects

[0013] Low-grade compatibility: With a minimum operating temperature difference ΔT ≥ 10℃, it can generate electricity stably in urban heating network scenarios such as industrial waste heat and low-temperature solar thermal collectors.

[0014] High efficiency: Conversion efficiency ≥5.4% (laboratory target ≥12%) at ΔT=90℃ (Th120 / Tc30), system heat recovery rate ≥85%;

[0015] High reliability: cold end ≤30℃, temperature difference fluctuation <±2℃, MTBF≥50000h, design life≥20 years;

[0016] Intelligentization: Cloud platform multi-unit collaborative scheduling + edge autonomy improve overall energy efficiency and operation and maintenance efficiency;

[0017] Scene gain: Free cold source in winter environment, ΔT can reach 110℃, one of the best efficiency in the entire series;

[0018] Scenario benefits: Prefabricated containers can be hoisted on-site and put into operation within one day; bypass faults are automatically cut off without affecting heating. Attached Figure Description

[0019] Figure 1 This is a block diagram of the system configuration of the present invention;

[0020] Figure 2 This is a cross-sectional view of a cascaded thermopile module.

[0021] Figure 3 This is a flowchart of a heat pipe-liquid cooling composite thermal management process.

[0022] Figure 4 Flowchart of intelligent energy management and scheduling method;

[0023] Figure 5 This is a flowchart of the hybrid MPPT and power optimization algorithm. Detailed Implementation

[0024] Example 1: Materials and Structure

[0025] The thermoelectric conversion module employs a multi-layer cascaded semiconductor thermopile: the low-temperature section is composed of p-type (doped with Sb, Se, 0.5–2 wt%) and n-type (doped with I) bismuth telluride (Bi2Te3) based materials, while the high-temperature section uses cobaltite (CoSb3) based materials; a gradient doping transition region is set along the temperature difference direction. The thermoelectric leg thickness is ≤1 mm, and a high-voltage DC output is formed by connecting copper electrodes in series. A Cu-In flexible metal foil stress buffer layer is set between the chip and the aluminum nitride (AlN) ceramic substrate, and the module surface is coated with an Al2O3 passivation layer. The heat capture end adopts an embedded heat pipe heat spreader + aluminum nitride substrate + flexible thermally conductive silicone / graphene coating, with a hot-end temperature difference fluctuation of <±2℃. The embodiment of this urban heating network uses a core module TEG-CORE-M1 ×12000 pieces (100×PACK-A1, 10 columns × 10 layers).

[0026] Example 2: Thermal Management and Power Electronics

[0027] The cold end employs a microchannel liquid cooling plate with a phase change material (PCM) buffer layer, and the circulating coolant maintains the cold end temperature at ≤30℃; copper-water heat pipes are used for high-temperature applications, and aluminum-acetone heat pipes are used for low-temperature applications. Power electronics utilize synchronous rectification (MOSFETs replacing diodes), multi-port inverters (DC bus adaptive), and ZVS / ZCS soft switching; MPPT employs a hybrid algorithm combining perturbation observation and conductance increment methods, and uses PID control to adjust the coolant flow rate to maintain ΔT stability (algorithm flow is available in [link]). Figure 5 The cold end of this city's heating network implementation uses a secondary network for water supply and return / ambient air cooling.

[0028] Example 3: Energy Dispatch and Experimental Data

[0029] The edge control module collects telemetry data and sends it to the cloud platform via MQTT over TLS; the cloud platform predicts future ΔT and power generation, and optimizes heat flow distribution, MPPT settings, and energy storage charging and discharging (see process details). Figure 4 A 40ft containerized power plant was deployed in the primary return water (approximately 120℃) of a heat exchange station in a certain city: it outputs 103kW and is connected to the 10kV power grid when ΔT≈90℃, and the winter ΔT reaches 110℃. It has been running continuously for 4200h without performance degradation.

[0030] The above description is only a preferred embodiment of the present invention. All equivalent modifications made in accordance with the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A solid-state thermoelectric power generation system for urban heating network thermoelectric power generation, characterized in that, include: The heat capture module is used to connect to the return water / heat exchange station of the urban centralized heating primary network in a bypass heat extraction structure to collect the waste heat of the 70–130℃ pipeline hot water to the hot end; The cascaded thermoelectric conversion module consists of multiple thermoelectric units arranged along a temperature gradient. The low-temperature section uses p-type and n-type bismuth telluride-based semiconductor thermoelectric materials, while the high-temperature section uses cobaltite-based semiconductor thermoelectric materials. Driven by the temperature difference between the hot and cold ends, it outputs DC power through the Seebeck effect. The thermal management module includes a cold end and a phase change material buffer layer for secondary network water supply / return / ambient air cooling, used to maintain the cold end temperature and smooth out hot end fluctuations. The power electronics module includes a maximum power point tracking (MPPT) DC-DC converter and an inverter, converting DC power into stable AC power. The energy storage module is connected to the DC bus to smooth out output fluctuations. The edge control module is used for local data acquisition, energy dispatch, and communication. The cloud platform is used for multi-unit collaborative dispatch, monitoring, and prediction. The heat capture module, cascaded thermoelectric conversion module, thermal management module, power electronics module, energy storage module, edge control module, and cloud platform are connected in the order of energy flow and data flow.

2. The system according to claim 1, characterized in that, The heat capture module includes 10 sets of heat exchange units in parallel, a heat pipe heat exchange plate, and a high thermal conductivity ceramic substrate. The hot side is DN200 with a flow rate of 320 m³ / h. Each set can be isolated for maintenance, ensuring that the temperature difference at the hot end fluctuates less than ±2℃. The bypass design automatically cuts off faults without affecting the heating supply.

3. The system according to claim 1, characterized in that, In the bismuth telluride-based semiconductor thermoelectric material, the n-type material is doped with iodine (I), and the p-type material is doped with antimony (Sb) and selenium (Se) elements, with a doping amount of 0.5–2 wt%, so that the thermoelectric figure of merit ZT ≥ 1.2 @ 300 K; a gradient doping transition region is set between the low-temperature section and the high-temperature section.

4. The system according to claim 1, characterized in that, The liquid cooling plate of the thermal management module has a microchannel structure, which, together with the circulating coolant and the phase change material buffer layer, keeps the cold end temperature ≤30℃; copper-water heat pipes are used in high-temperature scenarios and aluminum-acetone heat pipes are used in low-temperature scenarios.

5. The system according to claim 1, characterized in that, The power electronic module adopts synchronous rectification technology and replaces freewheeling diodes with MOSFETs to reduce conduction losses; the inverter has a multi-port topology, has the ability to adaptively regulate DC bus voltage, and is compatible with energy storage and grid connection; and adopts zero-voltage / zero-current soft switching to reduce high-frequency switching losses.

6. The system according to claim 1, characterized in that, The system has a minimum operating temperature difference ΔT ≥ 10℃, a thermoelectric conversion efficiency ≥ 5.4% under the condition of ΔT = 90℃ (Th120 / Tc30), a system heat recovery rate ≥ 85%, a single module power range of 10W–5kW, and a design life of ≥ 20 years.

7. The system according to claim 1, characterized in that, It also includes a stress buffer layer, located between the thermoelectric chip and the ceramic substrate, which is a Cu-In flexible metal foil that absorbs mechanical stress from thermal cycling; and an Al2O3 passivation layer is coated on the module surface to prevent corrosion.

8. The system according to claim 1, characterized in that, The edge control module communicates with the cloud platform via MQTT over TLS, operates autonomously according to local caching policies when the network is disconnected, and supports secure OTA upgrades.

9. An energy dispatch and control method for low-grade thermal energy cascade recovery power generation, based on the system described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Collect telemetry data on heat source temperature, temperature difference ΔT, voltage, current, flow rate, and energy storage SOC; S2. Predict future temperature difference and power generation based on historical and real-time data; S3. Calculate the optimal scheduling target by combining net load demand and energy storage status; S4. Optimize and generate heat flow distribution, MPPT setting, and energy storage charging and discharging commands; S5. Send the commands to the edge control module for local closed-loop control; S6. Collect the execution results for closed-loop feedback and model self-learning.

10. The method according to claim 9, characterized in that, The MPPT in S4 uses a hybrid algorithm that combines the perturbation and observation method with the incremental conductance method: first, the perturbation and observation method is used to coarsely locate the maximum power point, then the incremental conductance method is used to finely track it, and the PID is used to adjust the coolant flow rate to maintain a stable temperature difference.

11. The method according to claim 9, characterized in that, The S3 scheduling objective is to maximize net power generation and minimize heat loss and lifespan degradation while satisfying load and grid connection constraints.

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