Energy recovery and heat supply system and method based on thermoelectric conversion

Abstract

The invention belongs to the technical field of waste heat recovery and discloses an energy recovery and heat supply system and method based on thermoelectric conversion, and the method comprises the steps that an energy recovery unit collects heat of an industrial waste heat source, and a circulating pump drives a heat transfer medium to circulate in a pipeline; a stable temperature difference is formed at the two ends of the thermoelectric module, and thermoelectric conversion is carried out; the electric energy management unit rectifies and stabilizes the electric energy output by the thermoelectric module; a part of the electric energy after voltage stabilization is stored in a storage battery pack; the electric heating boiler is driven by electric energy to work; the heated hot water is conveyed to an area needing heat supply; and the monitoring module is controlled to operate to perform operation processing according to a preset algorithm and heat supply requirements. The energy recovery and utilization efficiency is high, waste heat resources which are wasted originally can be effectively recovered and converted into electric energy and heat energy to be used, an electric energy storage device, an auxiliary heating device and a monitoring system are arranged, and heat supply stability and continuity can be guaranteed under various working conditions.

Description

Technical Field

[0001] The present application relates to the field of waste heat recovery technology, and more specifically, to an energy recovery and heating system and method based on thermoelectric conversion. Background Art

[0002] A large amount of waste heat resources are generated in the steel production process. These waste heat mainly come from the following aspects: sintering flue gas sensible heat generated by the sintering machine, sintering cake physical heat, etc., slag sensible heat generated by the blast furnace, blast furnace gas sensible heat, etc., converter flue gas sensible heat generated by the converter in the steelmaking process, heat transfer between the ladle wall and molten steel, etc. These heat energies are directly released into the air environment, resulting in a waste of resources.

[0003] The document with the prior art publication number CN103672835B provides a hot and humid gas energy recovery high temperature heat generation system, which is characterized by comprising: a primary absorber and a secondary absorber with absorption heat exchange tubes arranged inside; a primary generator and a secondary generator with heat supply tubes arranged inside; the liquid absorbent outlet of the primary absorber is connected to the liquid absorbent inlet of the secondary absorber, the liquid absorbent outlet of the secondary absorber is connected to the liquid absorbent inlet of the primary generator, the liquid absorbent outlet of the primary generator is connected to the liquid absorbent inlet of the secondary generator, and the liquid absorbent outlet of the secondary generator is connected to the liquid absorbent inlet of the primary absorber; and the secondary absorber and the secondary generator are connected through a steam pipeline, and the secondary generator conveys steam to the secondary absorber; the primary generator has a steam outlet for conveying steam outward, and the primary absorber is provided with a hot and humid gas inlet and outlet. The invention uses a liquid absorbent to absorb water vapor in the humid and hot exhaust gas, and converts it into steam at a higher temperature and a higher pressure for use in industrial production processes.

[0004] Although the above-mentioned prior art solutions can achieve relevant beneficial effects through the structure of the prior art, they still have the following defects: 1. It is impossible to monitor and control the process of energy recovery and conversion. 2. The efficiency of energy recovery and utilization is low.

[0005] In view of this, we propose an energy recovery and heating system and method based on thermoelectric conversion. Summary of the invention

[0006] 1. Technical problems to be solved

[0007] The purpose of the present application is to provide an energy recovery and heating system and method based on thermoelectric conversion, which solves the technical problems raised in the above-mentioned background technology, achieves high energy recovery and utilization efficiency, can effectively recover the waste heat resources that were originally wasted, convert them into electrical energy and thermal energy for utilization, reduce energy waste, and reduce energy consumption costs; by being equipped with electrical energy storage, auxiliary heating devices and a complete control and monitoring system, it can ensure the technical effect of stability and continuity of heating under various working conditions.

[0008] 2. Technical solution

[0009] The technical solution of the present application provides an energy recovery and heating system based on thermoelectric conversion, comprising:

[0010] Energy recovery unit: collects heat from waste heat sources such as industrial waste gas through a collection pipe that is resistant to high temperatures and has good thermal conductivity, transfers waste heat to a heat transfer medium such as thermal oil or water through a heat exchanger, and achieves continuous heat transfer through a medium transmission system. It includes a heat source collection module, a heat exchanger, and a medium transmission system;

[0011] Heat source collection module: According to different waste heat sources, high-temperature resistant and thermally conductive collection pipes are laid to collect the medium (gas or liquid) carrying waste heat.

[0012] Heat exchanger: A heat exchanger is connected to the end of the collection pipe. The heat exchanger adopts an efficient fin or plate structure to increase the heat exchange area, so that the waste heat can be quickly transferred to the heat transfer medium (including heat transfer oil, water, etc.) in the heat exchanger to achieve preliminary heat extraction.

[0013] Medium transmission system: The circulating pump drives the heat transfer medium to circulate in the energy recovery unit to ensure continuous heat exchange, so that the waste heat is continuously collected and transferred to the next link.

[0014] Thermoelectric conversion unit: including thermoelectric module, shell and tube heat exchanger and water-cooled heat exchanger;

[0015] Thermoelectric module: Select thermoelectric materials with excellent performance, make them into individual thermoelectric elements, and then assemble them into thermoelectric modules in a certain array form.

[0016] Shell and tube heat exchanger: It is composed of shell, tube bundle and other components. High temperature medium flows in the tube, and heat is transferred to the hot end of the thermoelectric module on the outer surface of the shell through the tube wall. Its tube bundle is composed of multiple small tubes, which increases the contact area and improves the heat exchange efficiency. This structure is pressure-resistant and has a large flow rate. It is suitable for treating industrial high-temperature waste gas or liquid, and it is durable and has a long service life.

[0017] Water-cooled heat exchanger: It consists of cooling water pipes, water cooling heads and water tanks. It absorbs the heat from the cold end of the thermoelectric module through cold water circulation to achieve efficient and stable cooling. It has high cooling efficiency, can handle high heat loads, maintain the low temperature of the cold end of the thermoelectric module, and improve the thermoelectric conversion efficiency. Water has a large specific heat capacity and small temperature changes.

[0018] A shell and tube heat exchanger and a water-cooled heat exchanger are connected on both sides of the thermoelectric module respectively. The hot end is connected to the high-temperature heat transfer medium pipeline from the energy recovery unit, and the cold end is maintained at a lower temperature by water cooling, forming a stable temperature difference environment and promoting the smooth progress of the thermoelectric conversion process.

[0019] Power management unit: includes rectification and voltage regulation module and power storage module; efficiently converts temperature difference into electrical energy.

[0020] Rectifier and voltage regulator module: includes a rectifier circuit and a voltage regulator circuit; the electric energy output by the thermoelectric module is generally direct current, but the voltage and current are not stable enough. The alternating current component is removed by the rectifier circuit, and then the voltage is stabilized within a suitable range by the voltage regulator circuit, which is convenient for subsequent use or storage.

[0021] Electric energy storage module: equipped with battery packs to store excess electric energy. When the demand for heating is large or the efficiency of thermoelectric conversion fluctuates, it can provide supplementary electric energy to ensure the stable operation of the heating system. It can also be connected to the power grid to realize the access of surplus electricity to the grid and improve the economic efficiency of energy utilization.

[0022] Heating unit: including heating equipment, auxiliary heating device, heating pipe network and heat regulating device;

[0023] Heating equipment: Electric heating boilers are used, and the electric energy output from the thermoelectric conversion unit is used to drive the electric heating boiler. The electric heating boiler is equipped with efficient heating rods or heating coils to convert electrical energy into thermal energy, and heat the water in the boiler to a suitable heating temperature.

[0024] Auxiliary heating device: Equipped with a backup gas heating device as a supplementary heat source to ensure uninterrupted heating supply.

[0025] Heating network: Lay a reasonable heating pipeline network to transport hot water from the heating equipment to the areas that need heating.

[0026] Heat regulating device: Heat regulating valves are installed at each heating branch or at the entrance of the room to adjust the hot water flow according to actual needs, thereby controlling the indoor heating temperature.

[0027] Control and monitoring module: including temperature sensor, flow sensor and control system;

[0028] Temperature sensors: Temperature sensors are installed at the inlet and outlet of the heat exchanger of the energy recovery unit, the hot end and cold end of the thermoelectric conversion unit, the boiler of the heating unit, and the key nodes of the heating network to monitor the temperature changes in each link in real time.

[0029] Flow sensor: Install flow sensors in heat transfer medium circulation pipelines, heating pipelines and other locations to monitor medium flow information, understand heat transfer conditions, and reasonably adjust heating power according to flow.

[0030] Control system: A programmable logic controller (PLC) is used to receive signals from various sensors and perform calculations based on the preset control algorithm and heating requirements. The control program is written to achieve functions such as speed regulation of the circulation pump, start and stop of the heat dissipation equipment in the thermoelectric conversion unit, power control of the heating equipment, and opening control of the heat regulating valve.

[0031] Further, the thermoelectric conversion unit integrates a system of thermoelectric modules, shell and tube heat exchangers and water-cooled heat exchangers to efficiently convert temperature differences into electrical energy, including the following steps:

[0032] 1. Thermoelectric module assembly:

[0033] 1.1. Preparation of thermoelectric materials: According to design requirements, purchase high-performance thermoelectric materials such as bismuth telluride and its alloys. Inspect and screen the purchased materials to remove defective or non-compliant parts.

[0034] 1.2. Cut the thermoelectric material into thermoelectric elements of specific size and shape.

[0035] 1.3. Thermoelectric element connection and module forming: Distinguish between P-type and N-type thermoelectric elements, and connect them in the predetermined series and parallel array forms. Use appropriate welding technology at the connection points to ensure the reliability and low resistance characteristics of the connection. Place the connected thermoelectric element array on a special insulating bracket or substrate, fix and package it to form a complete thermoelectric module.

[0036] 2. Shell and tube heat exchanger installation:

[0037] 2.1. Component inspection and preparation: Conduct a comprehensive inspection of the shell, tube bundle, tube sheet and head of the shell and tube heat exchanger to ensure that there are no manufacturing defects and no foreign matter left. According to the installation requirements of the hot end of the thermoelectric module, a special heat conduction structure is designed on the inner surface of the shell to ensure efficient heat conduction between the hot end of the thermoelectric module and the shell.

[0038] 2.2. Heat exchanger installation and connection: Install the shell and tube heat exchanger at the predetermined position so that it is properly connected to the high-temperature heat transfer medium pipeline from the energy recovery unit.

[0039] 3. Installation of water-cooled heat exchanger:

[0040] 3.1. Assembly of water cooling system components: Assemble the cooling water pipes, water cooling head and water tank. Arrange complex cooling water pipe channels inside the water cooling head according to the design requirements to ensure the sealing of the channels and the smoothness of the water flow.

[0041] 3.2. Install the water pump at a suitable position between the water tank and the cooling water pipe, connect the water inlet pipe and the water outlet pipe, and ensure that the water pump can drive the cold water circulation normally.

[0042] 3.3. Connect the water-cooled heat exchanger to the thermoelectric module: Fit the water-cooled head tightly to the cold end of the thermoelectric module, and use thermal paste or other thermal interface materials to fill the small gap between the two to improve the heat conduction efficiency. Connect the cooling water pipeline so that cold water can enter the cooling water pipe from the water tank through the water pump, absorb the heat from the cold end of the thermoelectric module through the water-cooled head, and then return to the water tank for heat dissipation or further cooling.

[0043] 4. Thermoelectric conversion:

[0044] 4.1. System pre-startup inspection: Before starting the entire thermoelectric conversion unit, conduct a comprehensive inspection of all connection parts, pipelines, electrical lines, etc. to ensure that there are no looseness, leakage, short circuit and other abnormal conditions. Check whether the water level in the water tank is normal, whether the water pump, thermoelectric module and other equipment are in good condition, and whether all sensors are working normally and have been calibrated.

[0045] 4.2. Start the supply of high-temperature heat transfer medium: Open the high-temperature heat transfer medium pipeline valve from the energy recovery unit to allow the high-temperature heat transfer medium to begin to flow into the tube bundle of the shell and tube heat exchanger. Monitor the flow, temperature, pressure and other parameters of the high-temperature heat transfer medium to ensure that it operates stably within the design range.

[0046] 4.3. Start the water cooling system: Start the water pump to allow the cold water in the water tank to circulate in the cooling water pipeline of the water-cooled heat exchanger. Monitor the water temperature, water pressure, water flow rate and other parameters of the water cooling system to ensure that the water cooling system can effectively remove the heat from the cold end of the thermoelectric module and maintain the cold end temperature stable.

[0047] 5. Thermoelectric conversion monitoring and control: As the high-temperature heat transfer medium flows in the shell-and-tube heat exchanger and the water cooling system operates, a stable temperature difference is formed at both ends of the thermoelectric module, and the thermoelectric conversion process begins. The output voltage and current of the thermoelectric module are monitored in real time through the voltage sensor and current sensor installed on the thermoelectric module, and the output power is calculated.

[0048] According to the efficiency of thermoelectric conversion and the output power requirements, the flow rate of high-temperature heat transfer medium, the water temperature of the water cooling system and other parameters are dynamically adjusted. For example, if the thermoelectric conversion efficiency is low, the flow rate of high-temperature heat transfer medium can be appropriately increased or the water temperature of the water cooling system can be reduced to increase the temperature difference between the two ends of the thermoelectric module and improve the thermoelectric conversion efficiency. At the same time, the electric energy output by the thermoelectric module is rectified, stabilized, and then transmitted to subsequent energy storage or power consumption equipment.

[0049] 6. System operation maintenance and troubleshooting: Regularly inspect equipment, clean dirt, check water quality and treat it to ensure long-term stable operation. When a fault occurs, shut down the system immediately, check and repair it according to the alarm information and records, and restart the system after troubleshooting to restore normal operation.

[0050] Furthermore, the control and monitoring module monitors the temperature and flow in real time, receives sensor signals, and processes them according to the preset algorithm and heating requirements to adjust the heating power, etc.; the following steps are included:

[0051] 1. Temperature monitoring:

[0052] 1.1. Sensor deployment: According to the different links that need to be monitored, appropriate temperature sensors are installed at the inlet and outlet of the heat exchanger of the energy recovery unit, the hot end and cold end of the thermoelectric conversion unit, the boiler of the heating unit, and the key nodes of the heating network.

[0053] 1.2. Data collection: Each temperature sensor collects the temperature value of the location in real time according to the set sampling frequency and converts it into a corresponding electrical signal.

[0054] 1.3. Data processing: After the data acquisition unit receives the electrical signal from the sensor, it uses the built-in analog-to-digital converter (ADC) to convert the analog electrical signal into a digital signal and filters the converted digital temperature data.

[0055] 1.4 Data feedback: The processed temperature data is fed back to the control system in real time through the internal communication bus in the prescribed data format (such as a specific data packet structure, including sensor number, acquisition time, temperature value and other information).

[0056] 2. Flow monitoring:

[0057] 2.1. Sensor installation: Select a suitable flow sensor based on factors such as the type of medium (liquid or gas), flow range, and pipe size. Install flow sensors in locations where flow needs to be monitored, such as heat transfer medium circulation pipes and heating pipes.

[0058] 2.2. Flow data acquisition: The flow sensor measures the flow of the medium in real time during the flow of the medium and converts the flow information into corresponding electrical signal output.

[0059] 2.3. Data processing and analysis: After receiving the signal from the flow sensor, the data acquisition unit performs analog-to-digital conversion, converts the analog signal into a digital signal, and then performs data verification and preliminary data analysis to extract the actual flow value. Combined with parameters such as the cross-sectional area of ​​the pipeline, the volume flow or mass flow of the medium is further calculated to accurately understand the heat transfer situation.

[0060] 3. The control system receives signals, performs calculations and controls:

[0061] 3.1. Signal reception and integration: The signal receiving unit in the control system is responsible for receiving signals from temperature sensors, flow sensors and other possible sensors (such as pressure sensors, etc.), classifying and organizing the received signals, identifying and storing them according to information such as sensor type and monitoring location, and building a complete system real-time status data set.

[0062] 3.2. Operational processing: According to the preset control algorithm, relevant temperature, flow rate and other data are extracted from the data set as input parameters. Corresponding mathematical operations and logical judgments are performed in the operation processing unit of the control system.

[0063] 3.3. Control execution: The control quantity obtained by the operation processing is converted into the corresponding execution signal through the control signal output unit to drive the corresponding execution device to act. Real-time dynamic adjustment is made according to the actual operation of each link of the system to ensure that the entire energy recovery and heating system based on thermoelectric conversion can operate stably and efficiently, meet the heating requirements, and realize the reasonable recovery and utilization of energy.

[0064] The present invention provides an energy recovery and heating method based on thermoelectric conversion, comprising the following steps:

[0065] S1. Waste heat collection: The energy recovery unit collects heat from waste heat sources such as industrial waste gas through high-temperature resistant and well-conductive pipes, and quickly transfers it to the heat transfer medium using a heat exchanger.

[0066] S2. Medium circulation: The heat transfer medium is driven to circulate in the pipeline through a circulation pump, and the pipeline is insulated to reduce heat loss.

[0067] S3. The shell and tube heat exchanger of the thermoelectric conversion unit performs heat exchange: the high-temperature heat transfer medium flows in the shell and tube heat exchanger to transfer heat to the hot end of the thermoelectric module, and the operating status of the heat exchanger components is checked regularly.

[0068] S4. Water-cooled heat exchanger cooling: The cold water is driven to circulate through a water pump to absorb the heat from the cold end of the thermoelectric module, which is then dissipated or cooled by other equipment.

[0069] S5. The rectifying and voltage stabilizing module of the power management unit performs rectification and voltage stabilization: the electric energy output by the thermoelectric module is rectified and voltage stabilized.

[0070] S6. Electric energy storage and distribution: a part of the stabilized electric energy is stored in the battery pack, and the other part is connected to the power grid to make the surplus power available to the grid.

[0071] S7, heating unit operation: use electric energy to drive the electric heating boiler to heat the water, monitor the power output at the same time, and start the auxiliary heating device when necessary.

[0072] S8. Heating pipe network transportation: The heated hot water is transported to the areas that need heating through the heating pipe network, and the hot water flow and indoor temperature are adjusted according to actual needs.

[0073] S9, control and monitor module operation: collect data in real time through temperature sensors and flow sensors, and the control system performs calculations and processing according to preset algorithms and heating requirements to ensure efficient, stable and safe operation of the system.

[0074] 3. Beneficial effects

[0075] One or more technical solutions provided in the technical solution of this application have at least the following technical effects or advantages:

[0076] 1. The present invention achieves high energy recovery and utilization efficiency, can effectively recover the waste heat resources that were originally wasted, convert them into electrical energy and thermal energy for utilization, reduce energy waste, and reduce energy consumption costs.

[0077] 2. The present invention has significant environmental benefits, especially for places such as industrial fields that generate a large amount of waste heat. By recycling and utilizing waste heat, it can indirectly reduce environmental impacts such as greenhouse gas emissions caused by burning fossil fuels to obtain the same amount of heat energy.

[0078] 3. The present invention is equipped with electric energy storage, auxiliary heating devices and a complete control and monitoring system, which can ensure the stability and continuity of heating under various working conditions.

[0079] 4. The present invention can be applied to a variety of scenarios: it can be applied to factories with a large amount of high-temperature exhaust gas emissions, such as steel mills, chemical plants, and cement plants, to recycle exhaust gas and waste heat for heating needs such as office areas and workshops within the factory, while reducing energy costs. It can be used as a supplement to the traditional heating system, connected to the urban heating network, and use dispersed waste heat resources to improve the energy efficiency and sustainability of the entire urban heating system. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 A schematic flow chart of an energy recovery and heating method based on thermoelectric conversion disclosed in a preferred embodiment of the present application;

[0081] Figure 2 This is a schematic structural diagram of an energy recovery and heating system based on thermoelectric conversion disclosed in a preferred embodiment of the present application. DETAILED DESCRIPTION

[0082] The present application is further described in detail below in conjunction with the accompanying drawings.

[0083] Reference Figure 1 and Figure 2 , the embodiment of the present application provides an energy recovery and heating system based on thermoelectric conversion, comprising:

[0084] Energy recovery unit: including heat source collection module, heat exchanger and medium transmission system;

[0085] Heat source collection module: For different waste heat sources (such as high-temperature waste gas emission pipelines in industrial production, etc.), high-temperature resistant and heat-conductive collection pipelines are laid to collect the medium (gas or liquid) carrying waste heat. For example, in a factory, the collection pipeline is connected along the exhaust gas emission path of large equipment to ensure the maximum capture of waste heat.

[0086] Heat exchanger: A heat exchanger is connected to the end of the collection pipe. The heat exchanger adopts an efficient fin or plate structure to increase the heat exchange area, so that the waste heat can be quickly transferred to the heat transfer medium (including heat transfer oil, water, etc.) in the heat exchanger to achieve preliminary heat extraction.

[0087] Medium transmission system: equipped with a circulation pump of appropriate power to drive the heat transfer medium to circulate in the energy recovery unit to ensure continuous heat exchange, so that waste heat is continuously collected and transferred to the next link. For example, according to parameters such as pipeline length, pipe diameter and required flow rate, a centrifugal pump with appropriate head and flow rate is selected. The outside of the pipeline for transmitting the heat transfer medium is well insulated, and the pipeline is wrapped with insulation materials such as rock wool and polyurethane foam to reduce heat loss during transmission and ensure that heat is efficiently delivered to the thermoelectric conversion unit.

[0088] Thermoelectric conversion unit: including thermoelectric module, shell and tube heat exchanger and water-cooled heat exchanger;

[0089] Thermoelectric module: Select thermoelectric materials with excellent performance, such as bismuth telluride and its alloys. These materials have a high Seebeck coefficient, low thermal conductivity and suitable electrical conductivity, and can effectively convert temperature differences into electrical energy. Thermoelectric materials are made into individual thermoelectric elements, and then assembled into thermoelectric modules in a certain array form. For example, multiple P-type and N-type thermoelectric elements are connected in series and in parallel to form a thermoelectric module that can withstand large temperature differences and output relatively stable voltage and current.

[0090] Shell and tube heat exchanger: It consists of a shell, a tube bundle, a tube sheet and a head. The high-temperature heat transfer medium flows in the tube, and the hot end of the thermoelectric module is installed on the inner surface of the shell or connected to the shell through a special heat-conducting structure. The tube bundle is usually composed of many small-diameter tubes, which can increase the contact area between the high-temperature medium and the shell (and the hot end of the thermoelectric module) and improve the heat exchange efficiency. The high-temperature exhaust gas flows in the tube bundle, and the heat is transferred to the hot end of the thermoelectric module on the outer surface of the shell through the tube wall. This structure can withstand higher pressures and larger flows, and is more suitable for processing large amounts of high-temperature exhaust gas or liquids generated in industrial processes. Moreover, its structure is relatively strong and has a long service life.

[0091] Water-cooled heat exchanger: It consists of cooling water pipes, water cooling heads and water tanks. The water cooling heads fit tightly with the cold end of the thermoelectric module, and the cooling water pipes form complex channels inside the water cooling heads. The cold water is driven by a water pump from the water tank, circulates through the cooling water pipes, absorbs the heat from the cold end of the thermoelectric module, and then returns to the water tank for heat dissipation or is cooled by other cooling equipment and circulated again. The water-cooled heat exchange structure can provide a more stable and efficient cooling effect. The cooling efficiency is high and it can handle higher heat loads, so that the cold end of the thermoelectric module can be maintained at a lower temperature, thereby ensuring a larger temperature difference and improving the thermoelectric conversion efficiency. In addition, water has a large specific heat capacity and can absorb and take away a large amount of heat while its own temperature changes relatively little.

[0092] A shell and tube heat exchanger and a water-cooled heat exchanger are connected on both sides of the thermoelectric module. The hot end is connected to the high-temperature heat transfer medium pipeline from the energy recovery unit, and the cold end is maintained at a lower temperature through water cooling (connecting the cooling water pipeline to allow cold water circulation to take away heat), forming a stable temperature difference environment and promoting the smooth progress of the thermoelectric conversion process.

[0093] Power management unit: includes rectification and voltage regulation module and power storage module; efficiently converts temperature difference into electrical energy.

[0094] Rectifier and voltage regulator module: includes a rectifier circuit and a voltage regulator circuit; the electric energy output by the thermoelectric module is generally direct current, but the voltage and current are not stable enough. The alternating current component is removed by the rectifier circuit, and then the voltage is stabilized within a suitable range by the voltage regulator circuit, which is convenient for subsequent use or storage.

[0095] The voltage stabilization circuit selects the switching voltage stabilization circuit, which mainly includes a switch tube (usually a power MOSFET), an inductor, a capacitor, a diode and a control circuit. The control circuit controls the on and off of the switch tube at a certain frequency. When the switch tube is turned on, the input voltage charges the capacitor through the inductor, and the inductor stores energy at the same time; when the switch tube is turned off, the inductor releases the stored energy and continues to charge the capacitor through the diode to maintain the output voltage. The output voltage is controlled by adjusting the on time (duty cycle) of the switch tube. The advantage is high efficiency, especially in the case of large current and large voltage difference, its advantage is more obvious. It can achieve a stable output voltage within a wide input voltage range.

[0096] The rectifier circuit uses a full-wave rectifier circuit. There are two common forms of full-wave rectifier circuits, one is a center-tapped full-wave rectifier circuit, and the other is a bridge rectifier circuit. The center-tapped full-wave rectifier circuit requires a transformer with a center tap and two diodes. The center tap of the secondary winding of the transformer divides the winding into two parts, the upper and lower parts. When the alternating current is in the positive half cycle, the upper winding supplies power to the load through a diode; when the alternating current is in the negative half cycle, the lower winding supplies power to the load through another diode. In this way, during the entire cycle, current passes through the load and the direction remains unchanged. The bridge rectifier circuit is composed of four diodes to form a bridge structure. Regardless of whether the alternating current is in the positive half cycle or the negative half cycle, two diodes are turned on, so that the current can pass through the load, and the direction is always consistent. The output voltage pulsation of the full-wave rectifier circuit is smaller than that of the half-wave rectifier circuit, and the average output voltage is twice that of the half-wave rectifier circuit, which can more effectively utilize the energy of the alternating current.

[0097] Electric energy storage module: equipped with battery packs (such as lithium-ion batteries, etc.) to store excess electric energy. When the demand for heating is large or the efficiency of thermoelectric conversion fluctuates, it can provide supplementary electric energy to ensure the stable operation of the heating system. It can also be connected to the power grid to realize the access of surplus electricity to the grid, thus improving the economic efficiency of energy utilization.

[0098] Heating unit: including heating equipment, auxiliary heating device, heating pipe network and heat regulating device;

[0099] Heating equipment: Electric heating boilers are used, and the electric energy output from the thermoelectric conversion unit is used to drive the electric heating boiler. The electric heating boiler is equipped with efficient heating rods or heating coils to convert electrical energy into thermal energy, and heat the water in the boiler to a suitable heating temperature.

[0100] Auxiliary heating device: Taking into account special circumstances such as insufficient electricity for thermoelectric conversion, a backup gas heating device or other traditional heating methods are equipped as a supplementary heat source to ensure uninterrupted heating.

[0101] Heating pipe network: lay a reasonable heating pipe network to transport hot water from the heating equipment to areas that need heating, such as residential buildings, factories, etc. Outdoor pipes should be buried deep, insulated and anti-corrosive, and indoor pipes should be reasonably distributed according to different room layouts, and heat should be dissipated to the indoor environment through radiators (such as radiators, floor heating coils, etc.).

[0102] Heat regulating device: Installing heat regulating valves at each heating branch or room entrance can adjust the hot water flow according to actual needs, thereby controlling the indoor heating temperature, achieving on-demand heating, and improving energy utilization efficiency.

[0103] Control and monitoring module: including temperature sensor, flow sensor and control system;

[0104] Temperature sensor: Install temperature sensors at the inlet and outlet of the heat exchanger of the energy recovery unit, the hot and cold ends of the thermoelectric conversion unit, the boiler of the heating unit, and key nodes of the heating network to monitor the temperature changes in each link in real time and feed back to the control system.

[0105] Flow sensor: Flow sensors are installed in heat transfer medium circulation pipelines, heating pipelines and other locations to monitor the flow information of the medium in order to understand the heat transfer situation and reasonably adjust the heating power according to the flow rate.

[0106] Control system: A programmable logic controller (PLC) is used to receive signals from various sensors and perform calculations based on preset control algorithms and heating requirements. The control program is written to achieve functions such as speed regulation of the circulation pump (controlling the circulation speed of the heat transfer medium according to heat demand and temperature changes), start and stop of the heat dissipation equipment in the thermoelectric conversion unit (maintaining a stable temperature difference), power control of the heating equipment (adjusting the heating temperature), and opening control of the heat regulating valve, to ensure efficient, stable and safe operation of the entire system.

[0107] Further, the thermoelectric conversion unit integrates a system of thermoelectric modules, shell and tube heat exchangers and water-cooled heat exchangers to efficiently convert temperature differences into electrical energy, including the following steps:

[0108] 1. Thermoelectric module assembly:

[0109] 1.1. Preparation of thermoelectric materials: According to design requirements, purchase thermoelectric materials with excellent performance such as bismuth telluride and its alloys. Ensure that the purity and quality of the materials meet the requirements, inspect and screen the purchased materials, and remove defective or non-compliant parts.

[0110] 1.2. Cut the thermoelectric material into thermoelectric elements of specific size and shape to facilitate subsequent series and parallel assembly. Ensure dimensional accuracy during the cutting process and use high-precision cutting equipment, such as laser cutting or precision wire cutting equipment, to reduce the impact of cutting on material properties.

[0111] 1.3. Thermoelectric element connection and module forming: Distinguish between P-type and N-type thermoelectric elements, and connect them in the predetermined series and parallel array forms. Use appropriate welding processes at the connection points, such as low-temperature brazing or hot pressing welding, to ensure the reliability and low resistance characteristics of the connection. During the welding process, parameters such as welding temperature, time and pressure must be strictly controlled to avoid thermal damage to the thermoelectric elements.

[0112] The connected thermoelectric element array is placed on a special insulating bracket or substrate, fixed and packaged to form a complete thermoelectric module. The packaging material has good insulation, thermal conductivity and mechanical strength, such as ceramic or high-performance polymer materials, to protect the internal structure of the thermoelectric module and promote heat transfer.

[0113] 2. Shell and tube heat exchanger installation:

[0114] 2.1. Component inspection and preparation: Conduct a comprehensive inspection of the shell, tube bundle, tube sheet and head of the shell and tube heat exchanger to ensure that there are no manufacturing defects and no foreign matter left. Check the integrity of the tube bundle to ensure that each tube is not blocked or leaking. According to the installation requirements of the hot end of the thermoelectric module, a special heat-conducting structure (such as a heat-conducting sheet, a heat-conducting adhesive layer, etc.) is designed on the inner surface of the shell to ensure efficient heat conduction between the hot end of the thermoelectric module and the shell.

[0115] 2.2. Heat exchanger installation and connection: Install the shell and tube heat exchanger at the predetermined position so that it is properly connected to the high-temperature heat transfer medium pipeline from the energy recovery unit. Use pipe fittings with good sealing performance at the connection parts, such as welding or flange connection, and install sealing gaskets to prevent leakage of high-temperature media. Install the hot end of the thermoelectric module tightly on the heat-conducting structure of the shell to ensure good contact between the two and minimize thermal resistance. Bolt tightening or other suitable fixing methods can be used to ensure that the hot end of the thermoelectric module will not loosen or shift during operation.

[0116] 3. Installation of water-cooled heat exchanger:

[0117] 3.1. Assembly of water cooling system components: Assemble the cooling water pipe, water cooling head and water tank. Arrange complex cooling water pipe channels inside the water cooling head according to the design requirements to ensure the sealing of the channels and the smoothness of the water flow. The cooling water pipes are made of corrosion-resistant and thermally conductive materials, such as copper pipes or stainless steel pipes.

[0118] 3.2. Install the water pump at a suitable position between the water tank and the cooling water pipe, connect the water inlet and outlet pipes, and ensure that the water pump can drive the cold water circulation normally. At the same time, set the water inlet, drain outlet and heat dissipation device (such as radiator or cooling fan) on the water tank to maintain the stability of the water temperature in the water tank.

[0119] 3.3. Connect the water-cooled heat exchanger to the thermoelectric module: Fit the water-cooled head tightly to the cold end of the thermoelectric module, and use thermal paste or other thermal interface materials to fill the small gap between the two to improve the heat conduction efficiency. Ensure that the water-cooled head and the cold end of the thermoelectric module are firmly fixed to prevent loosening during operation, which may cause a decrease in the cooling effect. Connect the cooling water pipeline so that cold water can enter the cooling water pipe from the water tank through the water pump, absorb the heat from the cold end of the thermoelectric module through the water-cooled head, and then return to the water tank for heat dissipation or further cooling. Check the sealing of the entire water-cooled pipeline system to prevent water leakage.

[0120] 4. Thermoelectric conversion:

[0121] 4.1. System pre-startup inspection: Before starting the entire thermoelectric conversion unit, conduct a comprehensive inspection of all connection parts, pipelines, electrical lines, etc. to ensure that there are no looseness, leakage, short circuit and other abnormal conditions. Check whether the water level in the water tank is normal, whether the water pump, thermoelectric module and other equipment are in good condition, and whether all sensors (such as temperature sensors, pressure sensors, etc.) are working properly and have been calibrated.

[0122] 4.2. Start the supply of high-temperature heat transfer medium: Open the high-temperature heat transfer medium pipeline valve from the energy recovery unit to allow the high-temperature heat transfer medium to begin to flow into the tube bundle of the shell and tube heat exchanger. Monitor the flow, temperature, pressure and other parameters of the high-temperature heat transfer medium to ensure that it operates stably within the design range. Adjust the flow of the high-temperature heat transfer medium by adjusting the pipeline valve opening or other flow control equipment as needed.

[0123] 4.3. Start the water cooling system: Start the water pump to make the cold water in the water tank circulate in the cooling water pipeline of the water-cooled heat exchanger. Monitor the water temperature, water pressure and water flow rate of the water cooling system to ensure that the water cooling system can effectively remove the heat from the cold end of the thermoelectric module and maintain the cold end temperature stable. According to the change of water temperature, start the heat dissipation device of the water tank (such as the radiator fan) in time to ensure that the water temperature in the water tank does not exceed the set value.

[0124] 5. Thermoelectric conversion monitoring and control: As the high-temperature heat transfer medium flows in the shell-and-tube heat exchanger and the water cooling system operates, a stable temperature difference is formed at both ends of the thermoelectric module, and the thermoelectric conversion process begins. The output voltage and current of the thermoelectric module are monitored in real time through the voltage sensor and current sensor installed on the thermoelectric module, and the output power is calculated.

[0125] The electromotive force generated by the thermoelectric module is calculated according to the following formula:

[0126] Where V TE Represents the electromotive force generated by the thermoelectric module. It is the electric energy driving force generated by the temperature difference between the two ends of the thermoelectric module. Its unit is volt (V). h Indicates the hot end temperature of the thermoelectric module, that is, the temperature of the side in contact with the high-temperature heat source. It is an important parameter affecting thermoelectric conversion. The unit is Kelvin (K) or Celsius (℃). c Represents the cold end temperature of the thermoelectric module, that is, the temperature of the side connected to the low-temperature heat dissipation end. Together with the hot end temperature, it determines the temperature difference between the two ends of the module. The unit is also Kelvin (K) or Celsius (℃). S is the Seebeck coefficient, which is an inherent characteristic parameter of the thermoelectric material. It reflects the ability of the material to convert the temperature difference into electromotive force. Different thermoelectric materials have different Seebeck coefficient values. The unit is usually volts per Kelvin (V / K). k is a correction factor, which is related to the characteristics of the thermoelectric material and is used to adjust the formula to more accurately match the actual performance of a specific thermoelectric material under different working conditions. Its specific value needs to be determined according to the thermoelectric material used. For example, for bismuth telluride and its alloys, it may be within a certain range. λ is the material structure influencing factor, which takes into account the influence of microstructural factors such as the crystal structure integrity and doping concentration distribution of the thermoelectric material on thermoelectric conversion. Different material preparation processes and conditions will lead to different values, thereby affecting the calculation results of the electromotive force, so as to reflect the role of material structure differences in the thermoelectric conversion process.

[0127] The output power of the thermoelectric module is calculated according to the following formula:

[0128] Where P TE It indicates the power output of the thermoelectric module, that is, the power output for work or power supply after thermoelectric conversion, in watts (W). L It is the load resistance, which is the resistive load connected to the output end of the thermoelectric module. Its size will affect the power output characteristics of the thermoelectric module. The unit is ohm. i It is the internal resistance of the thermoelectric module. It is the inherent resistance characteristic of the thermoelectric module itself. It will produce internal losses during the power transmission process. The unit is ohm. V TE It is the electromotive force generated by the thermoelectric module, which is determined by the temperature difference at both ends of the thermoelectric module and the characteristics of the thermoelectric material. u is the efficiency factor related to the quality of the thermoelectric material, which comprehensively reflects the influence of the purity of the material, the uniformity of the crystal structure, etc. on the thermoelectric conversion efficiency. When the value is higher, it means that the loss caused by the characteristics of the material itself during the power conversion process is smaller, and the thermoelectric module can more efficiently convert thermal energy into electrical energy and output power. β is the heat flow coefficient that characterizes the influence of heat flow on power, Qh is the actual heat flow, i.e. the actual rate at which the hot end of the thermoelectric module absorbs heat, Q 0 is the standard reference heat flow. The heat flow is directly related to the temperature difference maintenance and energy input at both ends of the thermoelectric module, which in turn affects the power output. For example, when the actual heat flow is greater than the standard reference heat flow (β>1), the thermoelectric module may have more energy input, and when other conditions remain unchanged, there is a tendency to increase the power output; otherwise, the power output may be reduced. δ is a correction term related to ambient temperature fluctuations; T env is the actual ambient temperature, T ref is the reference ambient temperature. Changes in ambient temperature will affect the heat dissipation of the thermoelectric module and the performance of the thermoelectric material, thus affecting the power output. When the actual ambient temperature is higher than the reference ambient temperature, δ>0, the power output may change to a certain extent (it may increase or decrease, depending on the thermal balance of the entire system and the material properties); when the actual ambient temperature is lower than the reference ambient temperature, δ<0, the power output will also change accordingly.

[0129] According to the efficiency of thermoelectric conversion and the output power requirements, the flow rate of high-temperature heat transfer medium, the water temperature of the water cooling system and other parameters are dynamically adjusted. For example, if the thermoelectric conversion efficiency is low, the flow rate of high-temperature heat transfer medium can be appropriately increased or the water temperature of the water cooling system can be reduced to increase the temperature difference between the two ends of the thermoelectric module and improve the thermoelectric conversion efficiency. At the same time, the electric energy output by the thermoelectric module is rectified, stabilized, and then transmitted to subsequent energy storage or power consumption equipment.

[0130] Calculate the heat transfer of a shell and tube heat exchanger according to the following formula:

[0131]

[0132] a k =1+0.002*(T hi -T ho );where Q HX Represents the heat transfer capacity of the shell and tube heat exchanger, that is, the amount of heat transferred from the high-temperature heat transfer medium to the hot end of the thermoelectric module during the heat exchange process, and the unit is usually watt (W). d It is the fouling coefficient related to the degree of fouling of the heat exchanger. It reflects the degree of obstruction of the heat transfer process caused by the fouling on the internal tube wall surface after long-term use of the heat exchanger. d =1, as the running time increases and the fouling situation gradually worsens, the value will gradually decrease, and its value range is between 0.5-1. For example, the smaller the value, the greater the obstacle of fouling to heat transfer, and the actual heat transfer will be reduced accordingly. K tIt is the turbulence enhancement coefficient related to the fluid flow state, which is used to reflect the influence of turbulence on heat transfer when the high-temperature heat transfer medium flows in the tube. When the fluid is in a laminar flow state, K t =1, as the turbulence of the fluid gradually increases, the heat transfer will become more complete due to the intense mixing of the fluid, K t The larger the value, the range is 1-5. For example, in the case of high turbulence (K t is a larger value), which helps to enhance the heat transfer effect of the heat exchanger and increase the amount of heat transferred. k is the thermal conductivity correction factor related to the change of thermal conductivity of the pipeline material with temperature, taking into account that the thermal conductivity of the pipeline material is not fixed, but will change with the temperature difference between the inlet and outlet of the high-temperature heat transfer medium during the heat exchange process. T hi With T ho are the inlet temperature and outlet temperature of the high-temperature heat transfer medium respectively. The greater the temperature difference, the k The larger the value, the more it reflects the corresponding effect of the change in the thermal conductivity of the pipe material on the heat transfer. HX It is the total heat transfer coefficient, which comprehensively characterizes the overall heat transfer performance of the heat exchanger. It is affected by many factors, such as the thermal conductivity of the tube wall, the convection heat transfer coefficient between the fluid and the tube wall, etc. HX It is the heat transfer area, which refers to the effective area involved in the heat exchange process, that is, the actual contact area between the high-temperature heat transfer medium and the hot end of the thermoelectric module through the heat exchanger for heat transfer, and the unit is square meters. h It is the hot end temperature of the thermoelectric module, which is the temperature of the contact part with the shell side of the heat exchanger. It and the inlet and outlet temperatures of the high-temperature heat transfer medium jointly determine the temperature difference in the heat exchange process, thereby affecting the heat transfer amount. The unit is Kelvin (K) or degrees Celsius (℃).

[0133] Calculate the heat absorption of the water-cooled heat exchanger according to the following formula:

[0134] Q CW =η p *F s *H c *K u *m w *c pw *ΔT w * ( 1+f r );H c =1+0.003*ψ; where Q CW Represents the amount of heat absorbed by the water-cooled heat exchanger from the cold end of the thermoelectric module. It indicates the total amount of heat taken away from the cold end of the thermoelectric module by the circulating water under specific water cooling system operating conditions. The unit is joule (J) or watt (W), depending on factors such as the time unit used for other quantities in the formula. wIt is the mass flow rate of circulating water, that is, the mass of water passing through the water cooling system per unit time. It determines the amount of water that can participate in heat exchange. The unit is usually kilograms per second (kg / s). pw It is the specific heat capacity of water, which is the inherent thermophysical property of water. It indicates the amount of heat absorbed by a unit mass of water when the unit temperature rises, and reflects the ability of water to store heat during the heat transfer process. w It is the temperature difference between the inlet and outlet of the circulating water, that is, the change in temperature of the circulating water from entering the water-cooled heat exchanger to flowing out. It directly reflects the effect of the circulating water absorbing heat during the heat exchange process. The unit is Kelvin (K) or Celsius (℃). r It is the resistance coefficient related to the roughness of the water cooling system pipe. The greater the pipe roughness, the greater the resistance when water flows through the pipe, which will affect the flow state of water and the heat exchange efficiency. This coefficient is used to quantify this influence and correct the heat absorption calculation. K u It is a correction factor related to the uneven distribution of water flow rate. When the water flow rate is unevenly distributed in the water cooling system pipe, the heat exchange efficiency of different parts will be inconsistent. This coefficient is used to adjust the formula for calculating heat absorption according to the uniformity of the water flow rate. The more uneven the water flow is, the higher the K u The smaller it is, the greater the negative impact on heat absorption. c is the humidity coefficient related to the influence of environmental humidity, ψ is the relative humidity of the environment, and the value range is 0-100%. The environmental humidity will indirectly affect the heat absorption effect of the water cooling system by affecting the evaporation and heat dissipation of water. The higher the humidity, the higher the heat absorption effect of the water cooling system. c The larger the value, the greater the correction to heat absorption. p It is an efficiency factor related to the operation efficiency of the water pump, which reflects the degree of deviation between the actual output power and the theoretical output power due to mechanical loss, hydraulic loss and other reasons during the actual operation of the water pump. The lower the operation efficiency of the water pump, the higher the deviation of the actual output power from the theoretical output power. p The smaller the F, the more parameters such as the flow rate and pressure of the circulating water will differ from the ideal state, which will affect the heat absorption, so this factor needs to be considered in the formula for correction. s is the frost coefficient related to the frost condition at the cold end. When there is no frost, F s =1, the more severe the frost, the higher the s The smaller the value, the range is 0-1. When frost appears on the cold end of the thermoelectric module, the frost layer will increase the thermal resistance, hinder the heat transfer from the cold end to the circulating water, and reduce the heat absorption efficiency. This coefficient is used to reflect the influence of frost on the heat absorption process, so as to more accurately calculate the actual heat absorption.

[0135] 6. System operation maintenance and troubleshooting: During the operation of the thermoelectric conversion unit, the equipment should be inspected regularly to check the operating conditions of each component, including the heat exchange effect of the heat exchanger, the sealing of the water cooling system, and the operating sound of the water pump. Clean the dirt on the surface of the heat exchanger in time, check the water quality in the water cooling system, and perform necessary water treatment to ensure the long-term stable operation of the system. When a system failure occurs, such as leakage of high-temperature heat transfer medium, water leakage in the water cooling system, abnormal output of the thermoelectric module, etc., stop the system operation immediately, and troubleshoot and repair the fault according to the fault alarm information and equipment operation records. After troubleshooting, re-debug and restart the system to ensure that the system resumes normal operation.

[0136] Furthermore, the control and monitoring module monitors the temperature and flow in real time, receives sensor signals, and processes them according to the preset algorithm and heating requirements to adjust the heating power, etc.; the following steps are included:

[0137] 1. Temperature monitoring:

[0138] 1.1. Sensor deployment: According to the different links that need to be monitored, install appropriate temperature sensors at the inlet and outlet of the heat exchanger of the energy recovery unit, the hot end and cold end of the thermoelectric conversion unit, the boiler of the heating unit, and the key nodes of the heating network. For example, for areas with high temperature and large fluctuation range, thermocouple temperature sensors can be used; for areas with relatively low temperature and high accuracy requirements, thermal resistance temperature sensors can be used. Ensure that the sensor is firmly installed and the probe is in full contact with the monitored medium to accurately obtain temperature data.

[0139] 1.2. Data collection: Each temperature sensor collects the temperature value of the location in real time according to the set sampling frequency, and converts it into a corresponding electrical signal (such as a voltage signal or a current signal, and different sensors have different conversion methods). The electrical signal is transmitted to the data acquisition unit in the control and monitoring module through a signal line or a wireless transmission module (such as based on Zigbee, Bluetooth and other wireless communication protocols, suitable for occasions where wiring is difficult).

[0140] 1.3. Data processing: After the data acquisition unit receives the electrical signal from the sensor, it uses the built-in analog-to-digital converter (ADC) to convert the analog electrical signal into a digital signal for subsequent processing. The converted digital temperature data is simply filtered to remove possible noise interference (such as using mean filtering, median filtering and other algorithms) to improve the accuracy of the data.

[0141] 1.4 Data feedback: The processed temperature data is fed back to the control system in real time through the internal communication bus (such as CAN bus, RS485 bus, etc. to ensure the stability and reliability of data transmission) in the prescribed data format (such as a specific data packet structure, including sensor number, acquisition time, temperature value and other information).

[0142] 2. Flow monitoring:

[0143] 2.1. Sensor installation: Select a suitable flow sensor based on factors such as the type of medium (liquid or gas), flow range, and pipe size. For example, for heating pipes with liquid media and high accuracy requirements, electromagnetic flow sensors can be used; for pipes with gas media, vortex flow sensors can be used. Install the sensor in locations where flow needs to be monitored, such as heat transfer medium circulation pipes and heating pipes. Ensure that the sensor is installed on the straight pipe section of the pipe and that there is enough straight pipe section length before and after (generally according to the sensor installation requirements, the length of the front straight pipe section is about 10 times the inner diameter of the pipe, and the length of the rear straight pipe section is about 5 times the inner diameter of the pipe) to avoid the influence of fluid flow conditions on measurement accuracy.

[0144] 2.2、Flow data acquisition: During the flow of the medium, the flow sensor measures the flow of the medium in real time based on its own working principle (such as the electromagnetic flow sensor using the electromagnetic induction principle, the vortex flow sensor based on the Karman vortex phenomenon, etc.), and converts the flow information into a corresponding electrical signal output. The electrical signal is transmitted to the data acquisition part of the control and monitoring module by wired (such as using a dedicated flow sensor signal transmission cable) or wireless (such as using a LoRa wireless transmission module, which is suitable for long distances and inconvenient wiring).

[0145] 2.3. Data processing and analysis: After receiving the signal from the flow sensor, the data acquisition unit performs analog-to-digital conversion, converts the analog signal into a digital signal, and then performs data verification (checking whether the data is complete and whether it complies with the transmission protocol, etc.) and preliminary data analysis to extract the actual flow value. Combined with parameters such as the cross-sectional area of ​​the pipeline (calculated based on the inner diameter of the pipeline), the volume flow or mass flow of the medium is further calculated (for gaseous media, factors such as temperature and pressure may also need to be considered for conversion) in order to accurately understand the heat transfer situation.

[0146] 3. The control system receives signals, performs calculations and controls:

[0147] 3.1. Signal reception and integration: The signal receiving unit in the control system is responsible for receiving signals from temperature sensors, flow sensors and other possible sensors (such as pressure sensors, etc.), which contain real-time operating status information of different links. The received signals are classified and sorted, and identified and stored according to information such as sensor type and monitoring location to build a complete system real-time status data set for subsequent unified call and analysis.

[0148] Liquid flow rate is calculated according to the following formula:

[0149] C σ =1+0.005(TT 0 );where Q v Represents the volume flow rate of the liquid, that is, the volume of liquid flowing through a certain cross-section of the pipe per unit time, and the unit is usually cubic meters per second. E is the induced electromotive force output by the electromagnetic flow sensor. The electromagnetic flow sensor works based on the principle of electromagnetic induction. When a conductive liquid flows in a magnetic field, an induced electromotive force will be generated. The magnitude of this electromotive force is related to factors such as the flow rate of the liquid, and the unit is volt. D is the inner diameter of the pipe, which is a geometric dimension parameter of the pipe. It is used to determine the size of the cross-sectional area of ​​the pipe, and thus plays a key role in flow calculation. The unit is meter. B is the magnetic field strength, which is a physical quantity that generates a magnetic field for an electromagnetic flow sensor. The magnetic field is a key factor in causing charged particles (ions, etc.) in the liquid to move and generate an induced electromotive force, and the unit is Tesla. σ is the electrical conductivity of the liquid, which indicates the ability of the liquid to conduct electric current. Liquids with different electrical conductivities have different relationships between the induced electromotive force and flow under the same magnetic field and pipeline conditions. C r It is a correction factor related to the roughness of the inner wall of the pipe, which is used to consider the influence of the inner wall roughness of the pipe on the flow measurement. The inner wall roughness of the pipe will affect the flow state of the liquid and the interaction with the sensor. When the inner wall of the pipe is smooth, C r The value is larger; when the inner wall of the pipe is rough, the value is smaller. v It is the velocity distribution coefficient related to the uneven distribution of liquid velocity, and is used to correct the influence of the uneven velocity distribution of liquid in the pipeline on the flow calculation. If the velocity distribution of the liquid in the pipeline is very uniform, C v If the flow velocity distribution is uneven, C v The value is smaller. C σ is the conductivity temperature coefficient related to the effect of liquid temperature on conductivity, T is the actual temperature of the liquid, T 0 The conductivity of a liquid changes with temperature, and this factor is used to adjust the effect of conductivity on flow calculations based on the liquid temperature.

[0150] The gas flow rate is calculated according to the following formula:

[0151] C g =1+0.003*X; In the formula, Q vg Represents the volume flow rate of gas, that is, the volume of gas flowing through a certain cross-section of the pipeline per unit time. The unit is usually cubic meters per second. It is a physical quantity that we finally calculate through relevant parameters and correction coefficients to reflect the gas flow situation. f refers to the vortex frequency detected by the vortex flow sensor. The vortex flow sensor works based on the Karman vortex street phenomenon. When the gas flows through the vortex generator in the sensor, regular vortices will be generated alternately on both sides of its downstream. The frequency of these vortices corresponds to the flow rate of the gas. The gas flow rate is indirectly calculated by detecting this vortex frequency. The unit is Hertz. d is the pipe diameter, which describes the thickness of the pipe. It is a key geometric parameter for determining the size of the cross-sectional area of ​​the pipe. It plays a fundamental role in flow calculation. The unit is meter. St is the Strouhal number. For vortex generators of a specific shape, it is a constant. The Strouhal numbers corresponding to vortex generators of different shapes (such as cylindrical, triangular prism, etc.) are different. This value reflects a fixed relationship between the vortex frequency and the gas flow rate and the characteristic size of the pipe. C p C is the compression coefficient related to the compressibility of the gas. P is the absolute pressure of the gas, measured in Pascals. Gas is compressible, and the pressure will affect its volume and other properties. As the absolute pressure of the gas increases, the degree of gas compression increases. p The value will become smaller. This coefficient is used to correct the impact of gas compressibility on flow calculation, so as to more accurately reflect the gas flow under actual working conditions. r It is the roughness correction factor related to the roughness of the inner surface of the pipeline. Different inner surface roughness of the pipeline will change the flow state of the gas in the pipeline. For example, the rough inner surface will cause more resistance and turbulence when the gas flows, thus affecting the accuracy of flow measurement. u It is the velocity non-uniformity correction coefficient related to the non-uniformity of gas velocity in the pipeline. △v is the difference between the maximum velocity and the minimum velocity in the pipeline, in meters per second. In the actual pipeline gas flow, due to various factors (such as changes in local pipeline resistance, air intake conditions at different positions, etc.), the gas velocity is often not evenly distributed. The higher the non-uniformity of the velocity, the larger △v is, and C u The smaller the value, the greater the impact of uneven flow rate on flow measurement. gIt is the component correction coefficient related to the change of gas components. X is the percentage of the key gas component content deviating from the standard value. Different gas components have different physical properties (such as density, viscosity, etc.). When the content of the key component in the gas changes and deviates from the standard ratio, it will change the overall flow characteristics of the gas, thereby affecting the flow measurement results. g This factor is used to adjust the flow calculation according to composition changes.

[0152] 3.2. Operational processing: According to the preset control algorithm (which can be based on classical control theory, such as PID control algorithm, or more complex intelligent control algorithms, such as fuzzy control, neural network control, etc., selected according to the complexity of the system and the control accuracy requirements), extract relevant temperature, flow and other data from the data set as input parameters. Perform corresponding mathematical operations and logical judgments in the control system's operation processing unit (generally composed of core components such as microprocessors and programmable logic controllers PLC). For example, for the PID control algorithm, the control quantity (such as the change in the opening of the regulating valve, the power adjustment of the heating equipment, etc.) is calculated based on the deviation between the current temperature and flow and the set target temperature and flow. The control strategy is:

[0153]

[0154] Cnl =1+0.003*|e(t)| 0.5 ; In the formula, U(t) represents the output value of the PID controller at time. In the pressure control system, this output value will act on the corresponding actuator (such as adjusting the opening of the pressure valve, controlling the power of the pressure pump, etc.), thereby affecting the actual pressure of the system and causing it to change in the direction of the set pressure. The unit will be determined according to the specific actuator and pressure control scenario. K p Is the proportional term coefficient, an important parameter in the PID control algorithm, used to determine the proportion of the controller output that is proportional to the deviation e(t). It determines the sensitivity of the system to the deviation response, K p The larger the value, the greater the change in the controller output will be once a deviation occurs, which enables the system to respond quickly to correct the deviation. i Is the integral term coefficient, one of the key parameters in the PID control algorithm. Its function is to perform an integral operation on the deviation e(t). As time goes by, the influence of the deviation accumulates continuously. Even if the deviation is small but persists, the controller output is continuously adjusted through the integral term to eliminate the steady-state error of the system, so that the system can eventually stabilize at the set value. dis the differential term coefficient, which is a component of the PID control algorithm. It determines the weight of the part of the controller output related to the rate of change of the deviation. The differential term can be adjusted in advance according to the trend of the deviation. e(t) is the deviation between the set value and the actual value, that is, the difference between the set pressure and the current actual pressure. K ada It is the adaptive coefficient related to the adaptive adjustment of control parameters. It mainly dynamically adjusts its size according to the deviation change rate to achieve adaptive changes in control parameters. nl It is a nonlinear coefficient related to the nonlinear characteristics of the system, which is used to reflect the influence of nonlinear factors in the system on control.

[0155] 3.3. Control execution: The control quantity obtained by the operation processing is converted into a corresponding execution signal through the control signal output unit (such as using power drive elements such as relays and thyristors) to drive the corresponding execution equipment (such as adjusting the speed of the circulation pump, controlling the start and stop of the heat dissipation equipment in the thermoelectric conversion unit, changing the power of the heating equipment, adjusting the opening of the heat regulating valve, etc.). The above signal reception, operation processing and control execution steps are continuously cycled, and adjustments are made in real time and dynamically according to the actual operation of each link of the system to ensure that the entire energy recovery and heating system based on thermoelectric conversion can operate stably and efficiently, meet the heating requirements, and realize the reasonable recovery and utilization of energy.

[0156] The present invention provides an energy recovery and heating method based on thermoelectric conversion, comprising the following steps:

[0157] S1. Waste heat collection: The energy recovery unit collects heat from waste heat sources such as industrial waste gas through high-temperature resistant and well-conductive pipes, and quickly transfers it to the heat transfer medium using a heat exchanger.

[0158] S2. Medium circulation: The heat transfer medium is driven to circulate in the pipeline through a circulation pump, and the pipeline is insulated to reduce heat loss.

[0159] S3. The shell and tube heat exchanger of the thermoelectric conversion unit performs heat exchange: the high-temperature heat transfer medium flows in the shell and tube heat exchanger to transfer heat to the hot end of the thermoelectric module, and the operating status of the heat exchanger components is checked regularly.

[0160] S4. Water-cooled heat exchanger cooling: The cold water is driven to circulate through a water pump to absorb the heat from the cold end of the thermoelectric module, which is then dissipated or cooled by other equipment.

[0161] S5. The rectifying and voltage stabilizing module of the power management unit performs rectification and voltage stabilization: the electric energy output by the thermoelectric module is rectified and voltage stabilized.

[0162] S6. Electric energy storage and distribution: a part of the stabilized electric energy is stored in the battery pack, and the other part is connected to the power grid to make the surplus power available to the grid.

[0163] S7, heating unit operation: use electric energy to drive the electric heating boiler to heat the water, monitor the power output at the same time, and start the auxiliary heating device when necessary.

[0164] S8. Heating pipe network transportation: The heated hot water is transported to the areas that need heating through the heating pipe network, and the hot water flow and indoor temperature are adjusted according to actual needs.

[0165] S9, control and monitor module operation: collect data in real time through temperature sensors and flow sensors, and the control system performs calculations and processing according to preset algorithms and heating requirements to ensure efficient, stable and safe operation of the system.

[0166] The working principle of the energy recovery and heating system based on thermoelectric conversion of the present invention is as follows: the energy recovery unit collects the heat of waste heat sources such as industrial waste gas through a high-temperature resistant and well-conductive pipe, and quickly transfers it to the heat transfer medium through a heat exchanger. The heat transfer medium is driven to circulate in the pipe by a circulating pump, and the pipe is insulated to reduce heat loss. The shell and tube heat exchanger of the thermoelectric conversion unit performs heat exchange, and the high-temperature heat transfer medium flows in the shell and tube heat exchanger to transfer heat to the hot end of the thermoelectric module, and the operation status of the heat exchanger components is regularly checked. The cold water is driven to circulate by a water pump to absorb the heat of the cold end of the thermoelectric module, and then dissipate the heat or be cooled by other equipment. The rectifier and voltage regulator module of the power management unit performs rectification and voltage regulation, and the electric energy output by the thermoelectric module is rectified and voltage-regulated. A part of the voltage-regulated electric energy is stored in a battery pack, and the other part is connected to the power grid to realize the surplus power access to the grid. The electric energy is used to drive the electric heating boiler to work, heat the water, and the power output is monitored at the same time, and the auxiliary heating device is started when necessary. The heated hot water is transported to the area that needs heating through the heating pipe network, and the hot water flow and indoor temperature are adjusted according to actual needs. The temperature sensor and flow sensor collect data in real time, and the control system performs calculations according to the preset algorithm and heating requirements to ensure efficient, stable and safe operation of the system.

[0167] The present invention achieves high energy recovery and utilization efficiency, can effectively recover the waste heat resources that were originally wasted, convert them into electrical energy and thermal energy for utilization, reduce energy waste, and reduce energy consumption costs. The environmental benefits are significant, especially for places such as industrial fields that generate a large amount of waste heat. By recycling and utilizing waste heat, the environmental impacts such as greenhouse gas emissions generated by burning fossil fuels to obtain the same amount of heat energy can be indirectly reduced. By equipping with electrical energy storage, auxiliary heating devices and a complete control and monitoring system, the stability and continuity of heating can be guaranteed under various working conditions.

[0168] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An energy recovery and heating method based on thermoelectric conversion, characterized in that: The following steps are involved: S1. Waste heat collection: The energy recovery unit collects the heat of industrial waste heat sources through pipelines and quickly transfers it to the heat transfer medium using a heat exchanger; S2, medium circulation: the heat transfer medium is driven to circulate in the pipeline by a circulation pump; S3, the shell and tube heat exchanger of the thermoelectric conversion unit performs heat exchange, and the high-temperature heat transfer medium flows in the shell and tube heat exchanger to transfer heat to the hot end of the thermoelectric module; S4, water-cooled heat exchanger cooling: The water pump drives the cold water to circulate, absorb the heat at the cold end of the thermoelectric module, and then dissipate the heat to cool it down; a stable temperature difference is formed at both ends of the thermoelectric module, and the thermoelectric conversion process begins; S5, the rectifying and voltage stabilizing module of the power management unit performs rectification and voltage stabilization on the power output by the thermoelectric module; S6, power storage and distribution: store part of the stabilized power in the battery pack, and connect the other part to the power grid to make the surplus power available on the grid; S7, heating unit operation: using electric energy to drive the electric heating boiler to heat water, while monitoring the power output and starting the auxiliary heating device when necessary; S8, heating pipe network transportation: The heated hot water is transported to the area requiring heating through the heating pipe network, and the hot water flow and indoor temperature are adjusted according to actual demand; S9, control and monitor module operation: collect data in real time through temperature sensors and flow sensors, and the control system performs calculations and processing according to preset algorithms and heating requirements to ensure efficient, stable and safe operation of the system.

2. The energy recovery and heating method based on thermoelectric conversion according to claim 1 is characterized in that: Step S4 includes the following steps: S41. System pre-startup check: Before starting, check the connections, pipes and electrical circuits to make sure there are no abnormalities, and confirm that the water tank water level, equipment status, and sensors are working properly and have been calibrated; S42, start the supply of high-temperature heat transfer medium: open the valve to allow the high-temperature medium to flow into the shell and tube heat exchanger, monitor the flow, temperature and pressure parameters to ensure stable operation; S43, start the water cooling system: start the water pump to circulate the cold water, monitor the water temperature, water pressure and water flow rate, ensure that the heat of the cold end of the thermoelectric module is effectively taken away, and maintain the temperature stable; S44, Thermoelectric conversion monitoring and control: After the high-temperature medium and the water cooling system are running, the thermoelectric module forms a temperature difference for conversion, and the voltage, current and output power are monitored in real time through sensors; according to the efficiency of thermoelectric conversion and the output power requirements, the flow rate of the high-temperature heat transfer medium and the water temperature parameters of the water cooling system are dynamically adjusted.

3. The energy recovery and heating method based on thermoelectric conversion according to claim 2 is characterized in that: In step S44, the electromotive force generated by the thermoelectric module is calculated according to the following formula: Where V TE Represents the electromotive force generated by the thermoelectric module; T h Indicates the hot end temperature of the thermoelectric module; T c represents the cold end temperature of the thermoelectric module; S is the Seebeck coefficient; k is the correction factor, which is related to the characteristics of the thermoelectric material; λ is the material structure influencing factor, which takes into account the influence of the crystal structure integrity and doping concentration distribution microstructure factors of the thermoelectric material on thermoelectric conversion.

4. The energy recovery and heating method based on thermoelectric conversion according to claim 2 is characterized in that: In step S44, the heat transfer capacity of the shell and tube heat exchanger is calculated according to the following formula: a k =1+0.002*(T hi -T ho );where Q HX Represents the heat transfer of the shell and tube heat exchanger; F d is the fouling coefficient related to the degree of fouling of the heat exchanger; a k is the thermal conductivity correction factor related to the change in thermal conductivity of the pipe material with temperature; T hi With T ho are the inlet temperature and outlet temperature of the high-temperature heat transfer medium; U HX is the overall heat transfer coefficient; A HX is the heat transfer area; T h is the hot end temperature of the thermoelectric module.

5. The energy recovery and heating method based on thermoelectric conversion according to claim 2 is characterized in that: In step S44, the output power of the thermoelectric module is calculated according to the following formula: δ=0.005*(T env -T ref );where P TE Represents the power output of the thermoelectric module; R L is the load resistance; R i is the internal resistance of the thermoelectric module; V TE is the electromotive force generated by the thermoelectric module; u is the efficiency factor related to the quality of the thermoelectric material; β is the heat flow coefficient that characterizes the effect of heat flow on power, Q h is the actual heat flow; Q0 is the standard reference heat flow; δ is the correction term related to ambient temperature fluctuation; T env is the actual ambient temperature, T ref is the reference ambient temperature.

6. The energy recovery and heating method based on thermoelectric conversion according to claim 2 is characterized in that: In step S44, the heat absorption of the water-cooled heat exchanger is calculated according to the following formula: Q CW =η p *F s *H c *K u *m w *c pw *ΔT w *(1+f r );H c =1+0.003*ψ; where Q CW Represents the water-cooled heat exchanger absorbing the heat at the cold end of the thermoelectric module; m w is the mass flow rate of circulating water; c pw is the specific heat capacity of water; △T w is the temperature difference between the inlet and outlet of the circulating water; f r is the resistance coefficient related to the roughness of the water cooling system pipe; K u is the correction factor related to the unevenness of water velocity; H c is the humidity coefficient related to the influence of ambient humidity; η p is the efficiency factor related to the operating efficiency of the pump; F s is the frost coefficient related to the frost condition at the cold end.

7. The energy recovery and heating method based on thermoelectric conversion according to claim 1 is characterized in that: Step S9 includes the following steps: S91, Temperature monitoring: S91.

1. Sensor deployment: Install temperature sensors at key links of energy recovery, thermoelectric conversion and heating; S91.2, data collection: each temperature sensor collects the temperature value of the location in real time and converts it into a corresponding electrical signal; S91.3, data processing: the data acquisition unit receives the sensor signal, converts it into a digital signal and then performs filtering processing; S91.4 Data feedback: The processed temperature data is fed back to the control system in real time through the internal communication bus in the prescribed data format; S92, flow monitoring: S92.

1. Sensor installation: Select flow sensors according to the media type, flow range and pipe size, and install them in the circulation and heating pipes to monitor flow; S92.

2. Flow data acquisition: The flow sensor measures the flow of the medium in real time during the flow of the medium, and converts the flow information into corresponding electrical signal output; S92.3, Data processing and analysis: The data acquisition unit receives the flow sensor signal, converts it into a digital signal, performs verification and analysis, calculates the medium flow rate in combination with the pipeline parameters, and understands the heat transfer situation; S93, the control system performs signal reception, calculation processing and control: S93.1, Signal reception and integration: The control system receives various sensor signals, classifies and organizes them, identifies and stores them, and builds a real-time status data set of the system; S93.2, calculation and processing: according to the preset control algorithm, extract the relevant temperature and flow data from the data set as input parameters, and perform corresponding mathematical operations and logical judgments in the calculation and processing unit of the control system; S93.3, Control execution: Output execution signals according to the calculation results, drive equipment to operate, and adjust system operation in real time to ensure stable and efficient heating and reasonable energy recovery and utilization.

8. The energy recovery and heating method based on thermoelectric conversion according to claim 7 is characterized in that: In step S93.1, the liquid flow rate is calculated according to the following formula: C σ =1+0.005(T-T0); where Q v represents the volume flow rate of the liquid; E is the induced electromotive force output by the electromagnetic flow sensor; D is the inner diameter of the pipe; B is the magnetic field strength; σ is the conductivity of the liquid; C r is the correction factor related to the roughness of the inner wall of the pipe; C v is the velocity distribution coefficient related to the uneven distribution of liquid velocity; C σ It is the conductivity temperature coefficient related to the effect of liquid temperature on conductivity, T is the actual temperature of the liquid, and T0 is the reference temperature; The gas flow rate is calculated according to the following formula: C g =1+0.003*X; In the formula, Q vg represents the volume flow rate of the gas; f refers to the vortex frequency detected by the vortex flow sensor; d is the pipe diameter; St is the Strouhal number; C p is the compression coefficient related to the compressibility of the gas, P is the absolute pressure of the gas; C r is the roughness correction factor related to the roughness of the inner surface of the pipe; C u is the velocity non-uniformity correction coefficient related to the non-uniformity of gas velocity in the pipeline, △v is the difference between the maximum velocity and the minimum velocity in the pipeline; C g is the component correction coefficient related to the change of gas components, and X is the percentage of the key gas component content deviating from the standard value.

9. The energy recovery and heating method based on thermoelectric conversion according to claim 7, characterized in that: In step S93.1, the control strategy is: C nl =1+0.003*|e(t)| 0.5 ; In the formula, U(t) represents the output value of the PID controller at time; K p is the proportional term coefficient; K i is the integral term coefficient; K d is the differential term coefficient; e(t) is the deviation between the set value and the actual value; K ada is the adaptive coefficient related to the adaptive adjustment of control parameters; K nl It is a nonlinear coefficient related to the nonlinear characteristics of the system, which is used to reflect the influence of nonlinear factors in the system on control.

10. An energy recovery and heating system based on thermoelectric conversion, comprising: Energy recovery unit, thermoelectric conversion unit, power management unit, heating unit and control monitoring module; characterized in that: Energy recovery unit: including heat source collection module, heat exchanger and medium transmission system; Heat source collection module: laying high temperature resistant heat conducting pipes to collect media from different waste heat sources; Heat exchanger: connected to the end of the collection pipe, using a high-efficiency structure to increase the heat exchange area, quickly transfer waste heat to the heat transfer medium, and achieve initial heat extraction; Medium transmission system: drives the heat transfer medium to circulate, ensures continuous heat exchange, and transfers waste heat to the next link; Thermoelectric conversion unit: including thermoelectric module, shell and tube heat exchanger and water-cooled heat exchanger; Thermoelectric module: components made of high-performance thermoelectric materials are assembled into thermoelectric modules in arrays; Shell and tube heat exchanger: It consists of a shell and multiple tube bundles, which increases the contact area and improves the heat exchange efficiency. It has a large pressure resistance and flow rate and is suitable for processing industrial high-temperature media. Water-cooled heat exchanger: It consists of water pipes, water cooling heads and water tanks. The cold water circulates to absorb heat to achieve efficient cooling. It can handle high heat loads, maintain low temperatures and improve thermoelectric efficiency. Power management unit: Efficiently converts temperature difference into electrical energy, including rectification and voltage regulation module and power storage module; Rectification and voltage stabilization module: including rectification circuit and voltage stabilization circuit; the alternating current component is removed by the rectification circuit, and the voltage is stabilized within a suitable range by the voltage stabilization circuit; Electric energy storage module: equipped with a battery pack to store excess electric energy, which can provide supplementary electric energy when the demand for heating is large or the efficiency of thermoelectric conversion fluctuates; Heating unit: including heating equipment, auxiliary heating device, heating pipe network and heat regulating device; Heating equipment: Use electric heating boilers, and use the electric energy output from the thermoelectric conversion unit to drive the electric heating boilers; Auxiliary heating device: equipped with a backup gas heating device as a supplementary heat source to ensure uninterrupted heating; Heating pipe network: Lay a reasonable heating pipe network to transport hot water from the heating equipment to the areas that need heating; Heat regulating device: Heat regulating valves are installed on each heating branch to adjust the hot water flow according to actual demand, thereby controlling the indoor heating temperature; Control and monitoring module: including temperature sensor, flow sensor and control system; Temperature sensor: installed at key locations of energy recovery, thermoelectric conversion and heating units to monitor temperature changes in real time; Flow sensor: installed in circulation and heating pipes to monitor medium flow, understand heat transfer and adjust heating power; Control system: PLC is used to receive sensor signals, and the signals are processed according to preset algorithms and heating requirements. The speed of the circulation pump, the start and stop of the cooling equipment, the heating power and the heat regulating valve are adjusted through the control program.

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