A method and device for recycling waste heat of cooling water of a processing equipment

Abstract

The application provides a processing equipment cooling water waste heat recycling method and device, which comprises the following steps: driving an electric regulating valve to adjust the opening degree, adjusting the main cooling water flow of a three-stage phase change heat exchange module to obtain main cooling water; controlling the main cooling water to flow through the three-stage phase change heat exchange module and intermediate heat exchange medium in turn to carry out countercurrent heat exchange, so as to obtain target intermediate heat exchange medium; based on the deviation between the outlet temperature of the target intermediate heat exchange medium after flowing into a phase change heat storage buffer tank and the phase change temperature of a phase change material, adjusting the ratio between the flow of the target intermediate heat exchange medium flowing to a domestic water independent heat exchange unit and the recirculation flow of the target intermediate heat exchange medium flowing back to the inlet of the three-stage phase change heat exchange module, so as to obtain an intermediate heat exchange medium flow path; based on the indirect isolated heat exchange of the intermediate heat exchange medium flowing to the domestic water independent heat exchange unit in the intermediate heat exchange medium flow path. The application improves the recycling efficiency of the processing equipment cooling water waste heat under dynamic fluctuation conditions and the stability of long-term operation of the system.

Description

Technical Field

[0001] This invention relates to the field of industrial waste heat recovery and thermal energy management technology, and in particular to a method and apparatus for recovering and utilizing waste heat from cooling water of processing equipment. Background Technology

[0002] In the precision machining industry, equipment cooling water carries a large amount of low-grade waste heat. Existing recovery systems mostly use single-stage or simple multi-stage plate heat exchangers for direct heat exchange.

[0003] However, cooling water temperature and flow rate fluctuate drastically with load. Traditional heat exchangers lack thermal inertia buffering, resulting in large fluctuations in outlet water temperature, poor user experience, and waste of high-quality heat energy due to heat exchange limits at high temperature peaks. Secondly, when the cooling water flow rate decreases or the temperature difference diminishes, the flow velocity inside the heat exchanger easily falls below the critical turbulent velocity, entering the laminar flow region. This not only leads to a sharp drop in heat transfer coefficient but also forms a stable fouling layer on the plate surface, causing irreversible efficiency degradation after long-term operation. Existing systems lack a physical mechanism that can simultaneously achieve graded matching of heat energy quality and active maintenance of the flow state at the heat exchange interface. Therefore, existing methods reduce the recovery efficiency of waste heat from the cooling water of processing equipment under dynamically fluctuating conditions and the long-term stability of the system. Summary of the Invention

[0004] This invention provides a method and apparatus for recovering and utilizing waste heat from cooling water in processing equipment, aiming to improve the recovery efficiency of waste heat from cooling water in processing equipment under dynamic fluctuation conditions and the long-term stability of the system.

[0005] In a first aspect, the present invention provides a method for recovering and utilizing waste heat from cooling water in processing equipment, comprising: The opening of the electric regulating valve in the cooling water diversion component is driven by the inlet pressure of the cooling water return pipe, which regulates the flow rate of the main cooling water entering the three-stage phase change heat module, so that the flow rate of the main cooling water is not lower than the preset minimum safe flow rate threshold, thus obtaining the main cooling water. The main cooling water flows sequentially through the first sensible heat precooling section, the second embedded fin phase change section, and the third sensible heat cryogenic section of the three-stage phase change heat exchange module. It exchanges heat with the intermediate heat exchange medium circulating in the closed loop in a counter-current manner, transferring the heat from the main cooling water to the intermediate heat exchange medium. This cools the main cooling water before it is discharged, and raises the temperature of the intermediate heat exchange medium to obtain the target intermediate heat exchange medium. Based on the deviation between the outlet temperature of the target intermediate heat exchange medium after it flows into the phase change heat storage buffer tank and the phase change temperature of the phase change material, the three-way regulating valve located in the outlet pipeline of the phase change heat storage buffer tank is driven to adjust the ratio of the flow rate of the target intermediate heat exchange medium to the independent heat exchange unit of domestic water to the recirculation flow rate back to the inlet of the three-stage phase change heat exchange module, so as to obtain the flow path of the intermediate heat exchange medium. Indirect isolation heat exchange is achieved by using the intermediate heat exchange medium flowing to the independent heat exchange unit of domestic water in the intermediate heat exchange medium flow path, so as to realize the recovery and utilization of waste heat of cooling water.

[0006] In a second aspect, the present invention also provides a device for recovering and utilizing waste heat from cooling water in processing equipment, for implementing the method for recovering and utilizing waste heat from cooling water in processing equipment as described in the first aspect; the device includes: The electric valve control module is used to drive the opening of the electric regulating valve in the cooling water diversion component based on the inlet pressure of the cooling water return pipe, and adjust the main cooling water flow rate entering the three-stage phase change heat transfer module so that the main cooling water flow rate is not lower than the preset minimum safe flow rate threshold, thus obtaining the main cooling water. The first heat exchange control module is used to control the main cooling water to flow sequentially through the first sensible heat precooling section, the second embedded fin phase change section and the third sensible heat cryogenic section of the three-stage phase change heat exchange module, and to exchange heat with the intermediate heat exchange medium circulating in the closed loop in a counter-current heat exchange, transferring the heat of the main cooling water to the intermediate heat exchange medium, so that the main cooling water is cooled down and discharged, and the intermediate heat exchange medium is heated to obtain the target intermediate heat exchange medium. The second heat exchange control module is used to drive a three-way regulating valve located in the outlet pipeline of the phase change heat storage buffer tank based on the deviation between the outlet temperature of the target intermediate heat exchange medium after it flows into the phase change heat storage buffer tank and the phase change temperature of the phase change material. This regulates the ratio of the flow rate of the target intermediate heat exchange medium to the independent heat exchange unit of domestic water to the recirculation flow rate back to the inlet of the three-stage phase change heat exchange module, thus obtaining the flow path of the intermediate heat exchange medium. The third heat exchange control module is used to perform indirect isolation heat exchange based on the intermediate heat exchange medium flowing to the independent heat exchange unit of domestic water in the intermediate heat exchange medium flow path, so as to realize the recovery and utilization of waste heat of cooling water.

[0007] Thirdly, the present invention also provides an electronic device, comprising: a memory for storing a computer program; and a processor for reading and executing the computer program, thereby realizing the waste heat recovery and utilization method of cooling water for processing equipment as described above.

[0008] Fourthly, the present invention also provides a non-transitory computer-readable storage medium storing a computer program, which, when executed by a processor, implements the waste heat recovery and utilization method for cooling water of processing equipment as described above.

[0009] Fifthly, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the waste heat recovery and utilization method for cooling water of processing equipment as described above.

[0010] The waste heat recovery and utilization method for cooling water in processing equipment provided in this invention relies on the inlet pressure of the cooling water return pipe to drive the electric regulating valve of the diversion component to adjust the opening in real time. This dynamically adapts to the drastic fluctuations in cooling water temperature and flow rate, ensuring that the main cooling water flow rate entering the three-stage phase change heat exchange module is never lower than the preset minimum safe flow rate threshold. This eliminates the problem of low cooling water flow rate causing the internal flow velocity of the heat exchanger to fall into the laminar flow region, stably maintains the critical turbulent state of the heat exchange interface, avoids a sudden drop in heat transfer coefficient and the formation of a stable fouling layer on the plate surface, and eliminates the hidden danger of long-term irreversible decline in system heat exchange efficiency. The main cooling water is controlled to flow in a constant, stable flow state through the first stage sensible heat precooling section, the second stage embedded finned phase change section, and the third stage sensible heat cryogenic section of a three-stage phase change heat exchange module. It completes counter-current, tiered heat exchange with the closed-loop intermediate heat exchange medium. This staged heat exchange structure achieves graded matching and utilization of waste heat from the cooling water, avoiding the heat exchange limit problem inherent in traditional single, simple multi-stage heat exchange structures. It effectively recovers high-quality heat energy wasted during peak high-temperature periods, improving the waste heat recovery rate under dynamic operating conditions. Based on the deviation data between the outlet temperature of the target intermediate heat exchange medium and the phase change temperature of the phase change material, the flow ratio of the three-way regulating valve at the outlet of the phase change heat storage buffer tank is adjusted in real time. This dynamically allocates the heating flow rate of the independent domestic water heat exchange unit and the recirculation flow rate at the module inlet. Utilizing the thermal inertia characteristics of the phase change heat storage buffer tank, it offsets temperature and heat fluctuations caused by cooling water load fluctuations, stabilizing the overall heat exchange system's operating conditions and overcoming the large outlet water temperature fluctuations caused by the lack of thermal inertia buffering in traditional heat exchangers. Therefore, the embodiments of the present invention form a coordinated linkage from front-end flow stabilization and control, mid-stage high-efficiency heat exchange, and back-end thermal buffer condition optimization. Through the closed-loop coordination of flow regulation, stage phase change heat exchange, and temperature feedback diversion and recirculation, the active maintenance of the flow state at the heat exchange interface and the precise matching of the heat energy grade are realized simultaneously, which improves the recovery efficiency of waste heat of cooling water in processing equipment under dynamic fluctuation conditions and the stability of long-term system operation. Attached Figure Description

[0011] Figure 1 This is a flowchart of a method for recovering and utilizing waste heat from cooling water in processing equipment, provided in an embodiment of the present invention. Figure 2 This is a structural diagram of the waste heat recovery and utilization device for cooling water of processing equipment provided in an embodiment of the present invention; Figure 3 An embodiment diagram of the electronic device provided in this invention; Figure 4 An embodiment diagram of a computer-readable storage medium provided in accordance with the present invention. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0014] In the description of this invention, the term "for example" is used to mean "used as an example, illustration, or description." Any embodiment described as "for example" in this invention is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use the invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that the invention can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of the invention with unnecessary detail.

[0015] Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed herein.

[0016] Optionally, see Figure 1 , Figure 1 This is a flowchart of a method for recovering and utilizing waste heat from cooling water in processing equipment provided by the present invention. In this embodiment of the invention, the executing entity of the method for recovering and utilizing waste heat from cooling water in processing equipment is a waste heat recovery device. Therefore, the method for recovering and utilizing waste heat from cooling water in processing equipment includes: Step 10: Based on the inlet pressure of the cooling water return pipe, drive the opening of the electric regulating valve in the cooling water diversion assembly to adjust the main cooling water flow rate entering the three-stage phase change heat transfer module, so that the main cooling water flow rate is not lower than the preset minimum safe flow rate threshold, and obtain the main cooling water.

[0017] Optionally, this embodiment of the invention uses a waste heat recovery system for cooling water in a precision CNC machining center as an application scenario. The waste heat recovery device includes a cooling water diversion assembly, a three-stage phase change heat exchange module, a phase change heat storage buffer tank, an independent heat exchange unit for domestic water, and a self-cleaning backwashing pipeline.

[0018] Under full-load machining conditions, the total return flow rate of the cooling water return pipe in the precision CNC machining center is 12 cubic meters per hour, and the cooling water return temperature is 45 degrees Celsius. The preset minimum safe flow threshold of the electric regulating valve in the cooling water distribution assembly is 4 cubic meters per hour. This preset minimum safe flow threshold is the minimum volumetric flow rate required to maintain turbulent heat transfer in the internal cooling water flow channel of the three-stage phase change heat transfer module. The phase change material filled in the cavity of the second-stage embedded finned phase change section is a composite paraffin-based phase change material. The phase change temperature of this composite paraffin-based phase change material is 42 degrees Celsius, which is the starting temperature point for the solid-liquid phase transition of the composite paraffin-based phase change material. The liquidus characteristic temperature corresponding to the complete melting of the composite paraffin-based phase change material is 43 degrees Celsius, and the solidus characteristic temperature corresponding to the complete solidification of the composite paraffin-based phase change material is 41 degrees Celsius. The intermediate heat exchange medium circulating in the closed loop is a 30% (by volume) propylene glycol aqueous solution, and the circulation flow rate of the intermediate heat exchange medium is 8 cubic meters per hour. The inlet temperature of the domestic water is 15 degrees Celsius, and the preset target temperature of the domestic water is 45 degrees Celsius.

[0019] Optionally, the waste heat recovery device distributes the flow of cooling water in the cooling water return pipe through a cooling water diversion assembly. A pressure sensor is installed at the inlet of the cooling water return pipe, which collects the pressure value at the inlet in real time. After receiving the pressure value, the control unit of the waste heat recovery device drives the opening of the electric regulating valve in the cooling water diversion assembly according to the difference between the pressure value and the preset pressure reference value. When the opening of the electric regulating valve increases, the flow rate of the main cooling water entering the three-stage phase change heat transfer module increases. When the opening of the electric regulating valve decreases, the flow rate of the main cooling water entering the three-stage phase change heat transfer module decreases. During the adjustment process, the control unit continuously monitors the flow rate of the main cooling water entering the three-stage phase change heat transfer module to ensure that the flow rate of the main cooling water is not lower than the preset minimum safe flow threshold of 4 cubic meters per hour. When the flow rate of the main cooling water is adjusted to be not lower than the preset minimum safe flow threshold, the cooling water flowing through the electric regulating valve into the three-stage phase change heat transfer module is the main cooling water.

[0020] In one embodiment, assuming the real-time pressure value collected by the pressure sensor at the inlet of the cooling water return pipe is 0.35 MPa, and the preset pressure reference value is 0.30 MPa, the pressure difference is 0.05 MPa, indicating that the current inlet pressure of the cooling water return pipe is higher than the preset pressure reference value, and there is excess driving head in the cooling water return pipe. Based on the positive pressure difference of 0.05 MPa, the control unit, for example, increases the opening of the electric regulating valve in the cooling water diversion assembly from the current 40% to 65%, increasing the main cooling water flow rate entering the three-stage phase change heat exchange module from 6 cubic meters per hour to 8 cubic meters per hour. Since 8 cubic meters per hour is greater than the preset minimum safe flow rate threshold of 4 cubic meters per hour, the lower flow limit constraint is met. At this time, the 8 cubic meters per hour cooling water at a temperature of 45 degrees Celsius entering the three-stage phase change heat exchange module becomes the main cooling water. The remaining 4 cubic meters per hour of cooling water flows back to the cooling water supply pipeline of the processing equipment via the bypass of the cooling water diversion assembly for direct reuse.

[0021] Step 20: Control the main cooling water to flow sequentially through the first sensible heat precooling section, the second embedded fin phase change section, and the third sensible heat cryogenic section of the three-stage phase change heat exchange module, and exchange heat with the intermediate heat exchange medium circulating in the closed loop in a counter-current heat exchange, transferring the heat from the main cooling water to the intermediate heat exchange medium, so that the main cooling water is cooled down and discharged, and the intermediate heat exchange medium is heated up to obtain the target intermediate heat exchange medium.

[0022] Optionally, the main cooling water is controlled to flow sequentially through the three-stage cascaded phase change heat exchange module in the order of the first-stage sensible heat precooling section, the second-stage embedded fin phase change section, and the third-stage sensible heat cryogenic section. Inside the three-stage cascaded phase change heat exchange module, the main cooling water undergoes counter-current heat exchange with the intermediate heat exchange medium circulating in a closed loop; that is, the flow direction of the main cooling water is opposite to the flow direction of the intermediate heat exchange medium. The first-stage sensible heat precooling section is used to reduce the temperature of the main cooling water from the initial reflux temperature to a preset range above the phase change temperature of the phase change material filled in the second-stage embedded fin phase change section. This ensures that the main cooling water remains above the phase change temperature of the phase change material when entering the second-stage embedded fin phase change section, preventing the phase change material from prematurely solidifying at the inlet and clogging the flow channel due to excessively low main cooling water temperature. The second-stage finned phase change section enhances heat transfer using embedded high thermal conductivity fins. It further cools the main cooling water by absorbing the latent heat of the phase change material, maintaining a stable outlet temperature of the intermediate heat exchange medium during the solid-liquid phase transition. The third-stage sensible heat cryogenic section recovers residual sensible heat from the main cooling water, cooling it to near ambient temperature before discharge. After these three stages of heat exchange, the heat in the main cooling water is transferred step-by-step to the intermediate heat exchange medium, raising its temperature to obtain the target intermediate heat exchange medium.

[0023] Continuing with the main cooling water obtained in step 10 above, its flow rate is 8 cubic meters per hour, and its temperature is 45 degrees Celsius. The main cooling water first enters the first-stage sensible heat precooling section, which reduces the temperature of the main cooling water from 45 degrees Celsius to 43 degrees Celsius. 43 degrees Celsius is higher than the phase change temperature of the composite paraffin-based phase change material (42 degrees Celsius), falling within the preset range above the phase change temperature. Subsequently, the main cooling water at 43 degrees Celsius enters the second-stage embedded fin phase change section. The composite paraffin-based phase change material in the second-stage embedded fin phase change section absorbs the heat released by the main cooling water and undergoes a phase change from solid to liquid, reducing the temperature of the main cooling water from 43 degrees Celsius to 40 degrees Celsius. Finally, the main cooling water at 40 degrees Celsius enters the third-stage sensible heat cryogenic section. The low-temperature intermediate heat exchange medium in this section absorbs the residual sensible heat in the main cooling water, reducing its temperature from 40 degrees Celsius to 32 degrees Celsius before discharge. The intermediate heat exchange medium flows in the opposite direction to the main cooling water in the closed loop. Entering the third-stage sensible heat cryogenic section at 28 degrees Celsius, it rises to 33 degrees Celsius after heat exchange, then enters the second-stage embedded fin phase change section, where its temperature rises to 38 degrees Celsius. Finally, it enters the first-stage sensible heat pre-cooling section, where its temperature rises to 42 degrees Celsius. The intermediate heat exchange medium exiting the first-stage sensible heat pre-cooling section at 42 degrees Celsius is the target intermediate heat exchange medium.

[0024] Step 30: Based on the deviation between the outlet temperature of the target intermediate heat exchange medium after flowing into the phase change heat storage buffer tank and the phase change temperature of the phase change material, drive the three-way regulating valve located in the outlet pipeline of the phase change heat storage buffer tank to adjust the ratio of the flow rate of the target intermediate heat exchange medium to the independent heat exchange unit of domestic water to the recirculation flow rate back to the inlet of the three-stage phase change heat exchange module, so as to obtain the intermediate heat exchange medium flow path with balanced heat energy distribution.

[0025] Optionally, the target intermediate heat exchange medium flows out of the three-stage phase change heat exchange module and enters the phase change heat storage buffer tank. The phase change heat storage buffer tank is filled with phase change material, and the phase change temperature of the phase change material is the same as that of the composite paraffin-based phase change material in the second-stage embedded finned phase change section, both being 42 degrees Celsius. After the target intermediate heat exchange medium flows into the phase change heat storage buffer tank, it exchanges heat with the phase change material inside the tank, and some of the heat is absorbed and stored by the phase change material. The control unit collects the outlet temperature of the intermediate heat exchange medium at the outlet of the phase change heat storage buffer tank and compares the outlet temperature with the phase change temperature of the phase change material to obtain the deviation value between the two. Based on the sign and magnitude of the deviation value, the control unit drives the three-way regulating valve located in the outlet pipeline of the phase change heat storage buffer tank to adjust the ratio of the flow rate of the target intermediate heat exchange medium to the independent heat exchange unit for domestic water to the recirculation flow rate back to the inlet of the three-stage phase change heat exchange module, forming a balanced flow path for the intermediate heat exchange medium. When the outlet temperature is higher than the phase change temperature, it indicates that the phase change material in the phase change heat storage buffer tank has not fully absorbed heat, and the heat carrying capacity of the intermediate heat exchange medium is excessive. In this case, the flow rate to the independent heat exchange unit for domestic water should be increased. When the outlet temperature is lower than the phase change temperature, it indicates that the phase change material in the phase change heat storage buffer tank is releasing stored heat to compensate for the insufficient heat of the intermediate heat exchange medium. In this case, the flow rate to the independent heat exchange unit for domestic water should be decreased.

[0026] Continuing with the target intermediate heat exchange medium obtained in step 20 above, its temperature is 42 degrees Celsius and its flow rate is 8 cubic meters per hour. After flowing into the phase change heat storage buffer tank, the target intermediate heat exchange medium exchanges heat with the composite paraffin-based phase change material inside the tank, which is also at a temperature of 42 degrees Celsius. Since the temperature of the target intermediate heat exchange medium is equal to the phase change temperature of the phase change material inside the tank, the tank is in a dynamic equilibrium state of heat storage and release, and the outlet temperature of the intermediate heat exchange medium at the tank outlet is 42 degrees Celsius. The deviation between the outlet temperature and the phase change temperature of the phase change material (42 degrees Celsius) is 0 degrees Celsius, indicating that the current heat storage state of the tank is at equilibrium. Based on this zero-deviation state, the control unit drives the three-way regulating valve to distribute the target intermediate heat exchange medium at a 50% ratio: 4 cubic meters per hour of intermediate heat exchange medium flows through the first outlet of the three-way regulating valve to the independent heat exchange unit for domestic water, serving as an external heating branch. The remaining 4 cubic meters per hour of intermediate heat exchange medium flows back to the inlet of the three-stage phase change heat exchange module via the second outlet of the three-way regulating valve, serving as an internal heat circulation branch. The sum of the mass flow rates of the intermediate heat exchange medium in the external heating branch and the internal heat circulation branch is 8 cubic meters per hour, which is equal to the total discharge flow rate of the phase change heat storage buffer tank. The heat energy achieves a distribution balance between the external load and the internal heat storage and release, resulting in a balanced intermediate heat exchange medium flow path.

[0027] Step 40: Drive the phase change material to absorb the heat released by the main cooling water and undergo a physical change, thus completing the countercurrent heat exchange between the main cooling water and the intermediate heat exchange medium.

[0028] Optionally, the waste heat recovery device uses the intermediate heat exchange medium flowing through the intermediate heat exchange medium path to drive the independent heat exchange unit for domestic water to complete indirect isolation heat exchange. Indirect isolation heat exchange means that heat is transferred between the intermediate heat exchange medium and the domestic water through a metal wall. After absorbing the heat carried by the intermediate heat exchange medium in the independent heat exchange unit, the temperature of the domestic water rises to reach a usable domestic hot water temperature, thereby realizing the recovery and utilization of waste heat from the industrial side to the domestic side.

[0029] Continuing the aforementioned intermediate heat exchange medium flow path, 4 cubic meters per hour of intermediate heat exchange medium at a temperature of 42 degrees Celsius flows through the first outlet of the three-way regulating valve to the independent heat exchange unit for domestic water. Domestic water at 15 degrees Celsius enters the independent heat exchange unit for domestic water, where it indirectly exchanges heat with the intermediate heat exchange medium flowing within through the metal wall. After absorbing the heat released by the intermediate heat exchange medium, the domestic water's temperature rises from 15 degrees Celsius to 45 degrees Celsius, achieving the target domestic water temperature of 45 degrees Celsius. The intermediate heat exchange medium, after releasing heat, decreases in temperature from 42 degrees Celsius to 33 degrees Celsius and flows back to the phase change heat storage buffer tank for a new heat storage cycle. Thus, the waste heat carried by the cooling water of the processing equipment is extracted through a three-stage phase change heat exchange module, stored and buffered in the phase change heat storage buffer tank, and finally transferred to the domestic water through the independent heat exchange unit for domestic water, achieving the recovery and utilization of waste heat from the cooling water.

[0030] This invention achieves full-process coordinated operation by controlling the flow at the front end, optimizing the heat exchange in the middle stage, and optimizing the heat buffer operation at the back end. Through the closed-loop coordination of flow regulation, phase change heat exchange in the middle stage, and temperature feedback diversion and recirculation, it realizes the active maintenance of the flow state at the heat exchange interface and the precise matching of the heat energy grade in the tiers. This improves the recovery efficiency of waste heat from the cooling water of the processing equipment under dynamic fluctuation conditions and the stability of the system in long-term operation.

[0031] Optionally, the process of countercurrent heat exchange between the main cooling water and the intermediate heat exchange medium includes steps 201 to 204: Step 201: The main cooling water is introduced into the tube side flow channel of the first-stage sensible heat precooling section, and the target intermediate heat exchange medium is introduced into the shell side flow channel of the first-stage sensible heat precooling section, so that the two form a counter-current convection arrangement in the flow direction.

[0032] Optionally, the waste heat recovery device introduces the main cooling water into the tube-side flow channel of the first-stage sensible heat precooling section and introduces the target intermediate heat exchange medium into the shell-side flow channel of the first-stage sensible heat precooling section. The tube-side flow channel is a fluid channel composed of multiple metal tube bundles inside the first-stage sensible heat precooling section, where the main cooling water flows. The shell-side flow channel is the annular space between the outside of the metal tube bundles and the shell in the first-stage sensible heat precooling section, where the intermediate heat exchange medium flows. The flow direction of the main cooling water in the tube-side flow channel is opposite to the flow direction of the intermediate heat exchange medium in the shell-side flow channel, forming a counter-convective arrangement. The purpose of the counter-convective arrangement is to ensure that the section with the highest temperature at the main cooling water inlet corresponds to the section with the highest temperature at the intermediate heat exchange medium outlet, and the section with the lowest temperature at the main cooling water outlet corresponds to the section with the lowest temperature at the intermediate heat exchange medium inlet, maintaining a relatively uniform temperature difference driving force across the entire heat exchange length and improving heat exchange efficiency.

[0033] Continuing with the main cooling water obtained in step 10 above, its flow rate is 8 cubic meters per hour and its temperature is 45 degrees Celsius. The main cooling water enters from the inlet of the tube-side flow channel of the first-stage sensible heat precooling section and flows from the inlet end to the outlet end along the interior of the metal tube bundle. Simultaneously, the intermediate heat exchange medium at a temperature of 38 degrees Celsius enters from the inlet of the shell-side flow channel of the first-stage sensible heat precooling section. The shell-side flow channel inlet is located on the outlet side of the tube-side flow channel of the first-stage sensible heat precooling section. The intermediate heat exchange medium flows from the outlet side to the inlet side of the tube-side flow channel within the shell-side flow channel. The main cooling water flows from the inlet end to the outlet end of the tube-side flow channel, while the intermediate heat exchange medium flows from the outlet side to the inlet side of the shell-side flow channel, forming a counter-current flow arrangement.

[0034] Step 202: The sensible heat of the main cooling water is transferred to the target intermediate heat exchange medium by utilizing the thermal conductivity of the metal wall in the first-stage sensible heat precooling section, so that the temperature of the main cooling water is reduced to above the starting temperature point of the solid-liquid phase transition of the phase change material.

[0035] Optionally, during the flow of the main cooling water within the tube-side channels of the first-stage sensible heat precooling section, the heat from the main cooling water is transferred through the walls of the metal tube bundle to the intermediate heat exchange medium in the shell-side channels via thermal conduction. The walls of the metal tube bundle act as the heat conduction medium, transferring heat from the main cooling water side to the intermediate heat exchange medium side. The temperature of the main cooling water gradually decreases after releasing sensible heat. The heat exchange objective of the first-stage sensible heat precooling section is to reduce the outlet temperature of the main cooling water to above the starting temperature point of the solid-liquid phase transition of the phase change material, i.e., the temperature of the main cooling water leaving the first-stage sensible heat precooling section must be higher than the phase transition temperature of the composite paraffin-based phase change material in the second-stage embedded fin phase change section (42 degrees Celsius). The purpose of the temperature constraint is to ensure that when the main cooling water enters the second-stage embedded fin phase change section, its temperature is still higher than the phase transition temperature of the phase change material, allowing the phase change material to continuously absorb heat from the main cooling water and melt, without solidifying at the channel inlet due to excessively low main cooling water temperature.

[0036] In one embodiment, main cooling water at a temperature of 45 degrees Celsius flows within the tube-side channels of the first-stage sensible heat precooling section. Heat is transferred through the metal tube bundle walls to the intermediate heat exchange medium at a temperature of 38 degrees Celsius in the shell-side channels. As the main cooling water flows along the tube-side channels from the inlet to the outlet, its temperature gradually decreases from 45 degrees Celsius to 43 degrees Celsius. 43 degrees Celsius is higher than the initiation temperature of 42 degrees Celsius for the solid-liquid phase transition of the composite paraffin-based phase change material, satisfying the constraint that the outlet temperature of the main cooling water is higher than the phase change temperature. After absorbing the sensible heat released by the main cooling water in the shell-side channels, the intermediate heat exchange medium's temperature rises from 38 degrees Celsius to 42 degrees Celsius.

[0037] Step 203: The main cooling water that has been pre-cooled by sensible heat is introduced into the flow channel of the second-stage embedded fin phase change section, so that the main cooling water and the phase change material filled in the cavity of the second-stage embedded fin phase change section can be transferred through contact heat transfer via the embedded high thermal conductivity fins.

[0038] Optionally, the main cooling water, after sensible precooling in the first-stage sensible precooling section, is discharged from the tube-side flow channel outlet of the first-stage sensible precooling section and introduced into the flow channel of the second-stage embedded finned phase change section via interstage connecting pipes. The cavity of the second-stage embedded finned phase change section is filled with a composite paraffin-based phase change material, which is initially solid. Embedded high thermal conductivity fins are installed on the inner wall of the flow channel of the second-stage embedded finned phase change section. One end of the embedded high thermal conductivity fin is embedded inside the composite paraffin-based phase change material, and the other end extends into the flow channel to directly contact the main cooling water. The function of the embedded high thermal conductivity fins is to increase the effective heat exchange area between the composite paraffin-based phase change material and the main cooling water, and to accelerate the transfer of heat from the main cooling water to the composite paraffin-based phase change material using the high thermal conductivity of the material. When the main cooling water flows inside the flow channel of the second-stage embedded finned phase change section, it undergoes contact heat transfer with the embedded high thermal conductivity fins, and the heat is transferred to the composite paraffin-based phase change material through the embedded high thermal conductivity fins.

[0039] In one embodiment, main cooling water at a temperature of 43 degrees Celsius exits from the tube-side flow channel outlet of the first-stage sensible heat precooling section and enters the flow channel of the second-stage embedded finned phase change section via interstage connecting pipes. The composite paraffin-based phase change material filling the cavity of the second-stage embedded finned phase change section is currently in a solid state at a temperature of 41 degrees Celsius. As the main cooling water flows inside the flow channel, it comes into direct contact with the embedded high thermal conductivity fins, and the heat from the main cooling water is transferred to the embedded composite paraffin-based phase change material through the embedded high thermal conductivity fins. Since the temperature of the main cooling water (43 degrees Celsius) is higher than the phase change temperature (42 degrees Celsius) of the composite paraffin-based phase change material, the composite paraffin-based phase change material begins to absorb heat.

[0040] Step 204: Drive the phase change material to absorb the heat released by the main cooling water and undergo a physical change, thus completing the countercurrent heat exchange between the main cooling water and the intermediate heat exchange medium.

[0041] Optionally, the composite paraffin-based phase change material continuously absorbs heat released by the main cooling water. When the temperature of the composite paraffin-based phase change material reaches its phase change temperature of 42 degrees Celsius, it begins to undergo a phase change from solid to liquid. During this phase change, the heat absorbed by the composite paraffin-based phase change material is the latent heat of phase change. The temperature of the composite paraffin-based phase change material remains constant at the phase change temperature of 42 degrees Celsius until it completely transforms into a liquid state.

[0042] After the main cooling water releases heat in the second-stage embedded fin phase change section, its temperature further decreases, completing the countercurrent heat exchange between the main cooling water and the intermediate heat exchange medium, as detailed in steps 2041 to 2043.

[0043] In this embodiment of the invention, the main cooling water sequentially passes through a first-stage sensible heat precooling section for sensible heat transfer and a second-stage embedded finned phase change section for latent heat absorption of phase change, achieving a stepped heat transfer from the main cooling water to the intermediate heat exchange medium. The first-stage sensible heat precooling section efficiently transfers the high-temperature sensible heat of the main cooling water to the intermediate heat exchange medium in a counter-current arrangement, while precisely controlling the temperature of the main cooling water above the phase change temperature of the phase change material, creating stable inlet temperature conditions for the phase change heat transfer of the second-stage embedded finned phase change section. The second-stage embedded finned phase change section uses embedded high thermal conductivity fins to transfer heat from the main cooling water to the phase change material. Utilizing the constant temperature characteristic of the phase change material during the solid-liquid phase transition, the temperature of the intermediate heat exchange medium on the outlet side of the second-stage embedded finned phase change section remains stable during the phase change. This eliminates the disturbance of main cooling water temperature fluctuations to downstream heat exchange stages, allowing heat in the main cooling water to be extracted step by step according to temperature grade from high to low. This avoids the usable energy loss caused by the direct mixing of high-temperature heat and low-temperature heat exchange medium in single-stage heat exchange, and improves the recovery efficiency of waste heat from cooling water under dynamic fluctuation conditions.

[0044] Optionally, the processes of steps 2041 to 2043 include: Step 2041: Drive the phase change material to absorb the heat released by the main cooling water and undergo a physical change. During the physical change of the phase change material, maintain the temperature of the intermediate heat exchange medium on the outlet side of the second-stage embedded fin phase change section constant.

[0045] Optionally, the composite paraffin-based phase change material continuously absorbs heat released by the main cooling water and undergoes a phase change from solid to liquid within the second-stage finned phase change section. Throughout the entire phase change process, the temperature of the composite paraffin-based phase change material remains constant at its phase change temperature of 42 degrees Celsius, as the phase change is isothermal. The intermediate heat exchange medium at the outlet side of the second-stage finned phase change section exchanges heat with the composite paraffin-based phase change material through embedded high thermal conductivity fins. Because the temperature of the composite paraffin-based phase change material is constant, the temperature of the intermediate heat exchange medium at the outlet side of the second-stage finned phase change section is also maintained at a constant value. This constant temperature is the outlet temperature of the intermediate heat exchange medium corresponding to the phase change temperature of the phase change material.

[0046] During the phase change of the composite paraffin-based phase change material, regardless of the fluctuations in the inlet temperature or flow rate of the main cooling water, the temperature of the intermediate heat exchange medium on the outlet side of the second-stage embedded fin phase change section remains unchanged, thus acting as a temperature stabilizer.

[0047] In one embodiment, the composite paraffin-based phase change material is undergoing a phase change from solid to liquid, and its temperature remains constant at 42 degrees Celsius. The temperature of the intermediate heat exchange medium at the outlet side of the second-stage embedded finned phase change section is 38 degrees Celsius, and this temperature remains constant during the completion of the phase change of the composite paraffin-based phase change material. Assuming that the inlet temperature of the main cooling water fluctuates from 45 degrees Celsius to 47 degrees Celsius due to changes in the processing equipment load, the temperature of the intermediate heat exchange medium at the outlet side of the second-stage embedded finned phase change section remains unchanged at 38 degrees Celsius due to the isothermal phase change characteristics of the composite paraffin-based phase change material, and is unaffected by fluctuations in the main cooling water inlet temperature.

[0048] Step 2042: The main cooling water that has flowed through the second-stage embedded fin phase change section is transported to the third-stage sensible heat cryogenic section, where the low-temperature intermediate heat exchange medium in the third-stage sensible heat cryogenic section absorbs the residual sensible heat in the main cooling water.

[0049] Optionally, after the main cooling water flows through the second-stage finned phase change section, its temperature has decreased to below the phase change temperature of the phase change material. Some sensible heat remains in the main cooling water, requiring further recovery. The waste heat recovery device transports the main cooling water after the second-stage finned phase change section to the third-stage sensible heat cryogenic section. The third-stage sensible heat cryogenic section contains a low-temperature intermediate heat exchange medium returning from the closed loop. The temperature of the low-temperature intermediate heat exchange medium is lower than the temperature of the main cooling water when it enters the third-stage sensible heat cryogenic section. In the third-stage sensible heat cryogenic section, the main cooling water transfers its residual sensible heat to the low-temperature intermediate heat exchange medium, further reducing the temperature of the main cooling water. The low-temperature intermediate heat exchange medium absorbs heat and its temperature rises.

[0050] In one embodiment, the main cooling water reaches a temperature of 40 degrees Celsius after flowing through the second-stage embedded finned phase change section. This 40-degree Celsius main cooling water is then transported to the third-stage sensible heat cryogenic section. The temperature of the cryogenic intermediate heat exchange medium flowing within the third-stage sensible heat cryogenic section is 28 degrees Celsius. This cryogenic intermediate heat exchange medium enters the third-stage sensible heat cryogenic section from the return water pipe of the closed-loop system.

[0051] In the third-stage sensible heat cryogenic section, the main cooling water transfers its residual sensible heat to the low-temperature intermediate heat exchange medium at a temperature of 28 degrees Celsius. The temperature of the main cooling water decreases from 40 degrees Celsius to 32 degrees Celsius, and the temperature of the low-temperature intermediate heat exchange medium increases from 28 degrees Celsius to 33 degrees Celsius after absorbing heat.

[0052] Step 2043: The main cooling water after the three-stage heat exchange is discharged from the third-stage sensible heat cryogenic section, and the intermediate heat exchange medium that has absorbed all the heat is collected and transported to the inlet of the phase change heat storage buffer tank.

[0053] Optionally, after completing the three-stage heat exchange process—the first-stage sensible heat precooling section, the second-stage embedded finned phase change section, and the third-stage sensible heat cryogenic section—the temperature of the main cooling water has decreased to a level close to reusable. The waste heat recovery device discharges the main cooling water from the outlet of the third-stage sensible heat cryogenic section, and the discharged main cooling water flows back to the cooling water supply pipeline of the processing equipment to continue its cooling function. Simultaneously, the intermediate heat exchange media, which have absorbed heat in the three-stage phase change heat exchange modules, are collected from the outlets of each stage. The intermediate heat exchange media flowing out of the shell-side flow channel of the first-stage sensible heat precooling section has a temperature of 42 degrees Celsius, the intermediate heat exchange media flowing out of the second-stage embedded finned phase change section has a temperature of 38 degrees Celsius, and the intermediate heat exchange media flowing out of the third-stage sensible heat cryogenic section has a temperature of 33 degrees Celsius. The collected intermediate heat exchange media are transported via a collection pipeline to the inlet of the phase change heat storage buffer tank for heat storage.

[0054] In one embodiment, the main cooling water temperature after completing the three-stage heat exchange is 32 degrees Celsius. It is discharged from the outlet of the third-stage sensible heat cryogenic section and flows back to the cooling water supply pipeline of the precision CNC machining center. Intermediate heat exchange media with a temperature of 42 degrees Celsius flowing from the shell-side flow channel of the first-stage sensible heat precooling section, intermediate heat exchange media with a temperature of 38 degrees Celsius flowing from the second-stage embedded finned phase change section, and intermediate heat exchange media with a temperature of 33 degrees Celsius flowing from the third-stage sensible heat cryogenic section are mixed in a collecting pipeline and then transported to the inlet of the phase change heat storage buffer tank. The combined temperature of the collected intermediate heat exchange media is 42 degrees Celsius. This intermediate heat exchange media at this temperature is the target intermediate heat exchange media and enters the phase change heat storage buffer tank for further heat storage and distribution.

[0055] The embodiments of the present invention eliminate the instability of the intermediate heat exchange medium temperature under dynamic fluctuation conditions through the phase change isothermal characteristics, and at the same time improve the recovery efficiency of waste heat of the cooling water of the processing equipment by deeply recovering residual sensible heat through the third-stage sensible heat cryogenic section.

[0056] Optionally, the decoupling process between the first-stage sensible heat precooling section and the second-stage embedded fin phase change section includes steps 21 to 24: Step 21: Based on the comparison between the real-time outlet temperature of the intermediate heat exchange medium on the outlet side of the second-stage embedded fin phase change section and the liquidus characteristic temperature corresponding to the complete melting of the phase change material in the second-stage embedded fin phase change section, determine whether the phase change material in the second-stage embedded fin phase change section has completed the solid-liquid phase transition.

[0057] Optionally, the waste heat recovery device determines the phase change completion status of the composite paraffin-based phase change material in the second-stage embedded finned phase change section. The determination method is as follows: the real-time outlet temperature of the intermediate heat exchange medium on the outlet side of the second-stage embedded finned phase change section is collected, and the real-time outlet temperature is compared with the liquidus characteristic temperature corresponding to the complete melting of the composite paraffin-based phase change material in the second-stage embedded finned phase change section.

[0058] The liquidus characteristic temperature is the temperature at which the composite paraffin-based phase change material completely transforms from a solid to a liquid state; in this embodiment, it is 43 degrees Celsius. When the real-time outlet temperature reaches or exceeds the liquidus characteristic temperature, it indicates that the composite paraffin-based phase change material has absorbed sufficient heat and completed the phase transition from solid to liquid. When the real-time outlet temperature is below the liquidus characteristic temperature, it indicates that the composite paraffin-based phase change material has not completely melted and remains in a solid-liquid coexistence state or a solid state.

[0059] In one embodiment, a temperature sensor collects the real-time outlet temperature of the intermediate heat exchange medium at the outlet side of the second-stage embedded finned phase change section, which is 43 degrees Celsius. The real-time outlet temperature of 43 degrees Celsius is compared with the liquidus characteristic temperature of 43 degrees Celsius corresponding to the complete melting of the composite paraffin-based phase change material. Since the real-time outlet temperature equals the liquidus characteristic temperature, it is determined that the composite paraffin-based phase change material in the second-stage embedded finned phase change section has completed the solid-liquid phase transition and is currently in a completely liquid state.

[0060] Step 22: After determining that the phase change material has completed the solid-liquid phase transition, close the interstage isolation shut-off valve on the pipeline between the outlet of the first-stage sensible heat precooling section and the inlet of the second-stage embedded fin phase change section to cut off the flow path of the main cooling water from the first-stage sensible heat precooling section to the second-stage embedded fin phase change section. Open the bypass switching valve at the inlet of the cross-stage bypass pipeline at the outlet of the first-stage sensible heat precooling section to introduce the main cooling water discharged from the first-stage sensible heat precooling section into the cross-stage bypass pipeline, so that the main cooling water bypasses the second-stage embedded fin phase change section.

[0061] Optionally, after determining that the composite paraffin-based phase change material has completed the solid-liquid phase transition, the waste heat recovery device performs an operational decoupling operation between the first-stage sensible heat precooling section and the second-stage embedded fin phase change section. First, the waste heat recovery device closes the interstage isolation shut-off valve on the pipeline between the outlet of the first-stage sensible heat precooling section and the inlet of the second-stage embedded fin phase change section, cutting off the flow path of the main cooling water from the first-stage sensible heat precooling section to the second-stage embedded fin phase change section. Then, the waste heat recovery device opens the bypass switching valve at the inlet of the cross-stage bypass pipeline at the outlet of the first-stage sensible heat precooling section, introducing the main cooling water discharged from the first-stage sensible heat precooling section into the cross-stage bypass pipeline. The cross-stage bypass pipeline connects the outlet of the first-stage sensible heat precooling section and the inlet of the third-stage sensible heat cryogenic section, allowing the main cooling water to bypass the second-stage embedded fin phase change section. The reason for decoupling is that the composite paraffin-based phase change material has completely melted into a liquid state and no longer has the ability to continue absorbing the latent heat of phase change. If the main cooling water continues to flow through the second-stage embedded fin phase change section, the liquid composite paraffin-based phase change material will continue to absorb heat in the form of sensible heat, causing the temperature of the composite paraffin-based phase change material to rise continuously beyond the design range and reduce the heat storage quality.

[0062] In one embodiment, after step 21 determines that the composite paraffin-based phase change material has completed the solid-liquid phase transition, a closing command is sent to the interstage isolation shut-off valve on the pipeline between the outlet of the first-stage sensible heat precooling section and the inlet of the second-stage embedded fin phase change section. The interstage isolation shut-off valve closes, cutting off the flow path of the main cooling water from the first-stage sensible heat precooling section to the second-stage embedded fin phase change section. Simultaneously, an opening command is sent to the bypass switching valve at the inlet of the cross-stage bypass pipeline at the outlet of the first-stage sensible heat precooling section, and the bypass switching valve opens. After the main cooling water at a temperature of 43 degrees Celsius is discharged from the first-stage sensible heat precooling section, it no longer enters the second-stage embedded fin phase change section, but instead enters the cross-stage bypass pipeline through the bypass switching valve, bypassing the second-stage embedded fin phase change section.

[0063] Step 23: Control the main cooling water in the bypass pipeline to flow into the inlet pipe section of the third-stage sensible heat cryogenic section, so that the main cooling water can continue to complete cryogenic heat exchange while skipping the second-stage embedded fin phase change section.

[0064] Optionally, the main cooling water entering the inter-stage bypass pipeline flows along the inter-stage bypass pipeline and eventually merges into the inlet section of the third-stage sensible heat cryogenic section. The main cooling water skips the second-stage embedded finned phase change section and directly enters the third-stage sensible heat cryogenic section to continue cryogenic heat exchange. Because the inter-stage bypass pipeline directly connects the outlet of the first-stage sensible heat precooling section to the inlet of the third-stage sensible heat cryogenic section, the continuous heat exchange process of the main cooling water is not interrupted by the decoupling of the second-stage embedded finned phase change section, and the main cooling water can still release residual sensible heat in the third-stage sensible heat cryogenic section.

[0065] In one embodiment, the main cooling water at a temperature of 43 degrees Celsius flows in a bypass pipeline and merges into the inlet section of the third-stage sensible heat cryogenic section. The main cooling water enters the third-stage sensible heat cryogenic section after skipping the second-stage embedded fin phase change section. In the third-stage sensible heat cryogenic section, it exchanges heat with a low-temperature intermediate heat exchange medium at a temperature of 28 degrees Celsius. After the temperature of the main cooling water decreases from 43 degrees Celsius to 32 degrees Celsius, it exits from the outlet of the third-stage sensible heat cryogenic section, continuing the cryogenic heat exchange process.

[0066] Step 24: Close the inlet and outlet valves on the cooling water side of the second-stage embedded fin phase change section, as well as the inlet and outlet valves on the intermediate heat exchange medium side, so that the second-stage embedded fin phase change section enters a closed heat storage state, sealing the absorbed latent heat of phase change inside the phase change material.

[0067] Optionally, after switching the flow path of the main cooling water to the cross-stage bypass pipeline, the waste heat recovery device performs a closed-off isolation operation on the second-stage embedded fin phase change section.

[0068] The waste heat recovery device closes the inlet and outlet valves on the cooling water side of the second-stage embedded fin phase change section, cutting off all passages for cooling water to enter and exit the second-stage embedded fin phase change section.

[0069] The waste heat recovery device closes the inlet and outlet valves on the side of the intermediate heat exchange medium in the second-stage embedded finned phase change section, cutting off all passages for the intermediate heat exchange medium to enter and exit the second-stage embedded finned phase change section.

[0070] After the shutdown operation is completed, the second-stage embedded finned phase change section is isolated from the external pipeline and enters a closed heat storage state. In the closed heat storage state, the composite paraffin-based phase change material is sealed in liquid form within the cavity of the second-stage embedded finned phase change section. The absorbed latent heat of phase change is stored inside the composite paraffin-based phase change material, waiting to be released through a solidification heat release process when the processing equipment is shut down or the cooling water load is reduced.

[0071] In one embodiment, the inlet and outlet valves of the cooling water side of the second-stage embedded finned phase change section are closed, as are the inlet and outlet valves of the intermediate heat exchange medium side of the second-stage embedded finned phase change section. The second-stage embedded finned phase change section is completely isolated from the external piping and enters a closed heat storage state. The composite paraffin-based phase change material inside the cavity of the second-stage embedded finned phase change section is currently in a completely liquid state, and the latent heat of phase change stored inside it is sealed and preserved.

[0072] The embodiments of the present invention realize independent operation control of each stage in the three-stage phase change heat transfer module, so that the second-stage embedded fin phase change section can exit the heat exchange circuit after completing the heat storage task without affecting the continuous operation of the system as a whole. At the same time, the stored heat energy is retained in the second-stage embedded fin phase change section for use in subsequent heat release conditions, thereby improving the flexibility and recovery efficiency of the system's heat energy management under dynamic fluctuation conditions.

[0073] Optionally, the decoupling process between the second-stage embedded fin phase change section and the third-stage sensible heat cryogenic section includes steps 25 to 28: Step 25: If the current phase state information of the phase change material in the inner cavity of the second-stage embedded fin phase change section indicates that the phase change material is changing from liquid to solid and releasing the stored latent heat of phase change to the outside, it is determined that the second-stage embedded fin phase change section has entered the solidification regeneration exothermic condition. The interstage isolation shut-off valve on the pipeline between the outlet of the second-stage embedded fin phase change section and the inlet of the third-stage sensible heat cryogenic section is closed, cutting off the flow path of the main cooling water from the second-stage embedded fin phase change section to the third-stage sensible heat cryogenic section.

[0074] Optionally, the waste heat recovery device monitors the current phase state information of the composite paraffin-based phase change material within the cavity of the second-stage embedded finned phase change section. When the phase state information indicates that the composite paraffin-based phase change material transitions from a liquid to a solid state and releases its stored latent heat of phase change to the outside, the waste heat recovery device determines that the second-stage embedded finned phase change section has entered the solidification regeneration exothermic state. The solidification regeneration exothermic state means that during the transition from a liquid to a solid state, the composite paraffin-based phase change material releases its previously stored latent heat of phase change to the outside.

[0075] After entering the solidification and regeneration exothermic state, the waste heat recovery device closes the interstage isolation shut-off valve on the pipeline between the outlet of the second-stage embedded finned phase change section and the inlet of the third-stage sensible heat cryogenic section, cutting off the flow path of the main cooling water from the second-stage embedded finned phase change section to the third-stage sensible heat cryogenic section. The purpose of closing the interstage isolation shut-off valve is to prevent the composite paraffin-based phase change material, which is currently solidifying and exothermic, from continuing to exchange heat with the flowing main cooling water, and to avoid the main cooling water absorbing the heat that should be output to the phase change heat storage buffer tank.

[0076] In one embodiment, the current phase state information of the composite paraffin-based phase change material in the inner cavity of the second-stage embedded fin phase change section was monitored as follows: the temperature of the composite paraffin-based phase change material began to decrease from 42 degrees Celsius, the composite paraffin-based phase change material transitioned from a liquid to a solid state, and was releasing the stored latent heat of phase change to the outside. It was determined that the second-stage embedded fin phase change section had entered the solidification regeneration exothermic state.

[0077] A closing command is sent to the interstage isolation shut-off valve on the pipeline between the outlet of the second-stage embedded finned phase change section and the inlet of the third-stage sensible heat cryogenic section. The interstage isolation shut-off valve closes, and the flow path of the main cooling water from the second-stage embedded finned phase change section to the third-stage sensible heat cryogenic section is cut off.

[0078] Step 26: Close the connecting valve on the intermediate heat exchange medium side between the second-stage embedded fin phase change section and the third-stage sensible heat cryogenic section, cut off the flow path of the intermediate heat exchange medium between the two stages, so that the second-stage embedded fin phase change section and the third-stage sensible heat cryogenic section achieve flow isolation on both the cooling water side and the intermediate heat exchange medium side.

[0079] Optionally, after closing the interstage isolation shut-off valve on the cooling water side, the waste heat recovery device closes the connecting valve on the intermediate heat exchange medium side between the second-stage embedded finned phase change section and the third-stage sensible heat cryogenic section, cutting off the flow path of the intermediate heat exchange medium between the two stages. At this point, the second-stage embedded finned phase change section and the third-stage sensible heat cryogenic section achieve flow isolation on both the cooling water side and the intermediate heat exchange medium side, with no fluid communication between the two stages. The purpose of achieving double-sided flow isolation is to ensure that the latent heat of phase change released by the second-stage embedded finned phase change section under solidification regeneration exothermic conditions does not leak to the third-stage sensible heat cryogenic section through the connecting pipe on the intermediate heat exchange medium side, but is instead guided to the designated output direction.

[0080] In one embodiment, a closing command is sent to the connecting valve on the intermediate heat exchange medium side between the second-stage embedded finned phase change section and the third-stage sensible heat cryogenic section, and the connecting valve closes. The second-stage embedded finned phase change section and the third-stage sensible heat cryogenic section are flow-isolated on both the cooling water side and the intermediate heat exchange medium side, and there is no fluid communication between the two stages.

[0081] Step 27: Open the conduction valve in the regeneration heat release pipeline from the outlet of the intermediate heat exchange medium side of the second-stage embedded finned phase change section to the phase change heat storage buffer tank, and drive the latent heat released by the solidification of the phase change material in the second-stage embedded finned phase change section to be input into the phase change heat storage buffer tank for storage through the regeneration heat release pipeline.

[0082] Optionally, the waste heat recovery device opens the valve in the regeneration heat release pipeline from the outlet of the intermediate heat exchange medium in the second-stage embedded finned phase change section to the phase change heat storage buffer tank. The regeneration heat release pipeline is a dedicated pipeline connecting the outlet of the intermediate heat exchange medium in the second-stage embedded finned phase change section to the inlet of the phase change heat storage buffer tank. After the valve opens, the latent heat of phase change released by the solidification of the composite paraffin-based phase change material in the second-stage embedded finned phase change section is transferred through the embedded high thermal conductivity fins to the intermediate heat exchange medium within the second-stage embedded finned phase change section. The intermediate heat exchange medium, carrying heat, flows into the phase change heat storage buffer tank via the regeneration heat release pipeline for storage. Upon receiving the heat, the phase change heat storage buffer tank stores the heat in the phase change material within the tank, providing it for use by subsequent independent heat exchange units for domestic water.

[0083] In one embodiment, an opening command is sent to the spool valve in the regeneration heat release pipeline, and the spool valve opens. The latent heat of phase change released by the solidification of the composite paraffin-based phase change material in the second-stage embedded finned phase change section is transferred through the embedded high thermal conductivity fins to the intermediate heat exchange medium in the second-stage embedded finned phase change section, raising the temperature of the intermediate heat exchange medium to 41 degrees Celsius. The intermediate heat exchange medium at 41 degrees Celsius flows into the phase change heat storage buffer tank through the regeneration heat release pipeline, storing the heat in the composite paraffin-based phase change material within the phase change heat storage buffer tank.

[0084] Step 28: Open the bypass valve in the cross-stage bypass pipeline connecting the outlet of the first-stage sensible heat precooling section and the inlet of the third-stage sensible heat cryogenic section, so that the main cooling water discharged from the first-stage sensible heat precooling section can be directly transported to the inlet of the third-stage sensible heat cryogenic section through the cross-stage bypass pipeline, so that the continuous heat exchange of the main cooling water is uninterrupted.

[0085] Optionally, the waste heat recovery device opens the bypass valve in the interstage bypass pipeline connecting the outlet of the first-stage sensible heat precooling section and the inlet of the third-stage sensible heat cryogenic section. This interstage bypass pipeline is the same as the one used in step 22. After the bypass valve opens, the main cooling water discharged from the first-stage sensible heat precooling section is directly transported to the inlet of the third-stage sensible heat cryogenic section via the interstage bypass pipeline. During the solidification and regeneration heat release condition of the second-stage embedded fin phase change section, the main cooling water bypasses the second-stage embedded fin phase change section via the interstage bypass pipeline and enters the third-stage sensible heat cryogenic section to continue heat exchange, ensuring uninterrupted continuous heat exchange of the main cooling water.

[0086] In one embodiment, an opening command is sent to a facilitator valve in the interstage bypass pipeline, and the facilitator valve opens. Main cooling water at a temperature of 43 degrees Celsius, after being discharged from the first-stage sensible heat precooling section, is directly transported to the inlet of the third-stage sensible heat cryogenic section via the interstage bypass pipeline.

[0087] The main cooling water exchanges heat with the low-temperature intermediate heat exchange medium in the third-stage sensible-thermal cryogenic section, and is discharged after its temperature drops from 43 degrees Celsius to 32 degrees Celsius. The continuous heat exchange process of the main cooling water is uninterrupted during the solidification and regeneration exothermic condition in the second-stage embedded fin phase change section.

[0088] This invention enables the latent heat of phase change absorbed by the second-stage embedded finned phase change section during the heat storage phase to be effectively recovered into the phase change heat storage buffer tank during the heat release phase, instead of being dissipated in the heat exchange process on the cooling water side. This achieves cross-time period transfer and utilization of the latent heat of phase change. Simultaneously, by opening the cross-stage bypass pipeline, the main cooling water can continue to complete heat exchange even after the second-stage embedded finned phase change section exits the heat exchange loop, ensuring uninterrupted operation of the entire system. The overall solution allows the previously stored heat to be released and transferred to the phase change heat storage buffer tank during periods when the cooling water load of the processing equipment decreases or the equipment is shut down, extending the time window for utilizing waste heat and improving the long-term stability of the system.

[0089] Optionally, the process of the intermediate heat exchange medium flow path for balanced heat distribution includes steps 31 to 34: Step 31: Collect real-time temperature data of the intermediate heat exchange medium at the outlet of the phase change heat storage buffer tank and the current phase state position information of the phase change material in the tank, and compare the real-time temperature data with the characteristic temperature points corresponding to the complete melting or solidification of the phase change material to determine the current heat carrying capacity state of the intermediate heat exchange medium.

[0090] Optionally, the waste heat recovery device collects real-time temperature data of the intermediate heat exchange medium at the outlet of the phase change thermal storage buffer tank, as well as the current phase state position information of the phase change material inside the tank. The current phase state position information reflects the position of the solid-liquid interface of the phase change material within the tank, i.e., the boundary between the melted and unmelted portions of the phase change material. The real-time temperature data is compared with the characteristic temperature points corresponding to complete melting and complete solidification of the phase change material. The characteristic temperature point corresponding to complete melting is 43 degrees Celsius, and the characteristic temperature point corresponding to complete solidification is 41 degrees Celsius. Based on the comparison results, the current heat carrying capacity state of the intermediate heat exchange medium is determined: when the real-time temperature is higher than the characteristic temperature point corresponding to complete melting, the heat carrying capacity state is high, indicating that the heat carried by the intermediate heat exchange medium exceeds the storage requirements of the phase change thermal storage buffer tank, and the excess heat can be output externally. When the real-time temperature is below the characteristic temperature point corresponding to complete solidification, the heat carrying capacity is in a low heat carrying capacity state, indicating that the heat carried by the intermediate heat exchange medium is insufficient to maintain external heating, and internal recirculation needs to be increased to supplement the heat. When the real-time temperature is between the characteristic temperature point corresponding to complete solidification and the characteristic temperature point corresponding to complete melting, the heat carrying capacity is in a normal heat carrying capacity state, indicating that heat storage and heat release are in dynamic equilibrium.

[0091] In one embodiment, the real-time temperature data of the intermediate heat exchange medium at the outlet of the phase change heat storage buffer tank is 42 degrees Celsius. At the same time, the current phase position information of the composite paraffin-based phase change material inside the phase change heat storage buffer tank is collected. The information indicates that the composite paraffin-based phase change material inside the phase change heat storage buffer tank is in a solid-liquid coexistence state, and the solid-liquid phase interface is located in the middle of the tank.

[0092] The real-time temperature of 42 degrees Celsius is compared with the characteristic temperature points of 43 degrees Celsius corresponding to complete melting and 41 degrees Celsius corresponding to complete solidification. Since 42 degrees Celsius is lower than 43 degrees Celsius but higher than 41 degrees Celsius, the current heat transfer capacity of the intermediate heat exchange medium is determined to be the normal heat transfer capacity state.

[0093] Step 32: Generate a valve core displacement command for the three-way control valve based on the heat carrying capacity status. The valve core displacement command indicates a change in the proportion of the connecting cross-sectional area of ​​the internal flow channels of the three-way control valve.

[0094] Optionally, the waste heat recovery device generates a valve core displacement command for the three-way regulating valve based on the heat carrying capacity status determined in step 31. The valve core displacement command is an electrical signal that controls the direction and amount of movement of the valve core inside the three-way regulating valve, indicating a change in the ratio of the connecting cross-sectional areas of the internal flow channels. When the heat carrying capacity status is high, the valve core displacement command instructs the increase of the connecting cross-sectional area of ​​the first outlet and the decrease of the connecting cross-sectional area of ​​the second outlet, allowing more intermediate heat exchange medium to flow to the independent heat exchange unit for domestic water. When the heat carrying capacity status is low, the valve core displacement command instructs the decrease of the connecting cross-sectional area of ​​the first outlet and the increase of the connecting cross-sectional area of ​​the second outlet, allowing more intermediate heat exchange medium to flow back to the inlet of the three-stage phase change heat exchange module for recirculation and heat storage. When the heat carrying capacity status is normal, the valve core displacement command instructs the maintenance of the ratio of the connecting cross-sectional areas of the first and second outlets.

[0095] In one embodiment, step 31 determines that the current heat transfer capacity of the intermediate heat exchange medium is in a normal heat transfer capacity state. Based on this normal heat transfer capacity state, a valve core displacement command is generated for the three-way regulating valve. This command instructs the three-way regulating valve to maintain its current valve core position, i.e., to maintain the ratio of the cross-sectional areas of the first outlet to the second outlet at 1:1. Inside the three-way regulating valve, the cross-sectional area of ​​the first outlet accounts for 50% of the total area, and the cross-sectional area of ​​the second outlet accounts for 50% of the total area.

[0096] Step 33: Control the first intermediate heat exchange medium to flow to the independent heat exchange unit for domestic water through the first outlet of the three-way regulating valve as an external heating branch, and control the remaining second intermediate heat exchange medium to flow back to the inlet of the three-stage phase change heat exchange module through the second outlet of the three-way regulating valve as an internal heat circulation branch.

[0097] Optionally, the waste heat recovery device controls the first intermediate heat exchange medium to flow to the independent domestic water heat exchange unit via the first outlet of the three-way regulating valve, serving as an external heating branch. The first intermediate heat exchange medium is a portion of the target intermediate heat exchange medium discharged from the phase change heat storage buffer tank, distributed to the first outlet via the three-way regulating valve. The heat carried by this portion of fluid is used to heat the domestic water in the independent domestic water heat exchange unit. Simultaneously, the waste heat recovery device controls the remaining second intermediate heat exchange medium to flow back to the inlet of the three-stage phase change heat exchange module via the second outlet of the three-way regulating valve, serving as an internal heat circulation branch. The second intermediate heat exchange medium is the remaining portion of the target intermediate heat exchange medium discharged from the phase change heat storage buffer tank, distributed to the second outlet via the three-way regulating valve. This portion of fluid flows back to the three-stage phase change heat exchange module and reabsorbs waste heat from the main cooling water, completing the internal heat recirculation replenishment. The external heating branch and the internal heat circulation branch together form two parallel pathways for the intermediate heat exchange medium flow path to balance heat energy distribution. The external heating branch is responsible for outputting stored heat to the external domestic water load, while the internal heat circulation branch is responsible for returning unoutputted heat to the heat exchange front end to maintain the system's continuous heat absorption capacity. The intermediate heat exchange medium in both branches originates from the same target intermediate heat exchange medium discharged from the phase change heat storage buffer tank. After physical diversion by a three-way regulating valve, they enter their respective functional paths. They share the same fluid source and are complementary in function.

[0098] In one embodiment, the total discharge flow rate of the target intermediate heat exchange medium from the phase change thermal storage buffer tank is 8 cubic meters per hour, and the temperature is 42 degrees Celsius. The first intermediate heat exchange medium is controlled to flow through the first outlet of a three-way regulating valve to the independent domestic water heat exchange unit. The flow rate of the first intermediate heat exchange medium is 4 cubic meters per hour, and the temperature is 42 degrees Celsius. This serves as an external heating branch. After entering the independent domestic water heat exchange unit, this 4 cubic meters per hour intermediate heat exchange medium indirectly isolates and exchanges heat with the domestic water, outputting heat to the external domestic water load. Simultaneously, the remaining second intermediate heat exchange medium is controlled to flow back through the second outlet of the three-way regulating valve to the inlet of the three-stage phase change heat exchange module. The flow rate of the second intermediate heat exchange medium is 4 cubic meters per hour, and the temperature is 42 degrees Celsius. This serves as an internal heat circulation branch. After flowing back to the three-stage phase change heat exchange module, this 4 cubic meters per hour intermediate heat exchange medium re-enters the closed-loop circulation, continuing to absorb waste heat from the main cooling water. The 4 cubic meters per hour in the external heating branch and the 4 cubic meters per hour in the internal heat circulation branch both originate from the same 8 cubic meters per hour target intermediate heat exchange medium discharged from the phase change heat storage buffer tank. After being physically diverted at a 1:1 ratio by the three-way regulating valve, they enter their respective functional paths and together form an intermediate heat exchange medium flow path with balanced heat energy distribution.

[0099] Step 34: Based on the valve core displacement command, adjust the flow cross-sectional area ratio of the external heating branch and the internal heat circulation branch so that the sum of the mass flow rates of the intermediate heat exchange medium in the external heating branch and the internal heat circulation branch is equal to the total discharge flow rate of the phase change heat storage buffer tank, thus completing the distribution of heat energy between the external load and the internal heat storage and release.

[0100] Optionally, based on the valve core displacement command generated in step 32, the waste heat recovery device drives the valve core inside the three-way regulating valve to shift, changing the cross-sectional area of ​​the first and second outlets within the three-way regulating valve. The change in cross-sectional area directly determines the distribution ratio of the intermediate heat exchange medium in the two branches. During the valve core displacement adjustment process, the waste heat recovery device adheres to the flow conservation constraint: the sum of the adjusted mass flow rate of the intermediate heat exchange medium in the external heating branch and the mass flow rate of the intermediate heat exchange medium in the internal heat circulation branch must equal the total discharge flow rate of the phase change heat storage buffer tank. The flow conservation constraint means that the intermediate heat exchange medium discharged from the phase change heat storage buffer tank is completely distributed to both the external heating branch and the internal heat circulation branch at any given time, without any stagnation or loss of the intermediate heat exchange medium. When the valve core displacement command indicates an increase in the cross-sectional area ratio of the first outlet, the mass flow rate of the intermediate heat exchange medium in the external heating branch increases accordingly, and the mass flow rate of the intermediate heat exchange medium in the internal heat circulation branch decreases accordingly, but the sum of the two always equals the total discharge flow rate of the phase change heat storage buffer tank. Conversely, after the above adjustments are completed, the heat carried by the intermediate heat exchange medium in the external heating branch is transported to the independent heat exchange unit for domestic water use to supply the external domestic water load, while the heat carried by the intermediate heat exchange medium in the internal heat circulation branch flows back to the three-stage phase change heat exchange module to continue absorbing the waste heat in the main cooling water. The heat energy is distributed between the external load and the internal heat storage and release, forming an intermediate heat exchange medium flow path with balanced heat energy distribution.

[0101] Continuing from step 33 above, the total discharge flow rate of the phase change thermal storage buffer tank is 8 cubic meters per hour, and the temperature is 42 degrees Celsius. The valve core displacement command generated in step 32 instructs the three-way regulating valve to maintain its current valve core position, i.e., the ratio of the connecting cross-sectional areas of the first outlet to the second outlet is 1:1. The valve core inside the three-way regulating valve is driven to execute the displacement command, with the connecting cross-sectional area of ​​the first outlet and the second outlet accounting for 50% of the total area. After adjustment, the mass flow rate of the intermediate heat exchange medium in the external heating branch is 4 cubic meters per hour, and the mass flow rate of the intermediate heat exchange medium in the internal heat circulation branch is 4 cubic meters per hour, totaling 8 cubic meters per hour, which equals the total discharge flow rate of the phase change thermal storage buffer tank of 8 cubic meters per hour, satisfying the flow conservation constraint. The 4 cubic meters per hour intermediate heat exchange medium at 42 degrees Celsius in the external heating branch flows to the independent domestic water heat exchange unit, providing heat to the external domestic water load. In the internal heat circulation branch, 4 cubic meters per hour of intermediate heat exchange medium at a temperature of 42 degrees Celsius is returned to the inlet of the three-stage phase change heat exchange module to continue absorbing the waste heat from the main cooling water. The heat energy is distributed between the external load and the internal heat storage and release, forming an intermediate heat exchange medium flow path with balanced heat energy distribution.

[0102] This invention determines the heat-carrying capacity status by fusing real-time temperature and phase position information, avoiding misjudgments caused by relying on a single parameter for flow allocation. Through continuous adjustable control of the connected cross-sectional area ratio via valve core displacement commands, the external heat supply ratio dynamically changes with the heat storage and release status of the phase change heat storage buffer tank. When heat storage is sufficient, the external heat supply ratio automatically increases to meet domestic water load demands; when heat storage is insufficient, the internal recirculation ratio automatically increases to prioritize heat replenishment. This maintains a balance between the heating stability of the independent heat exchange unit for domestic water and the continuous heat absorption capacity of the three-stage phase change heat exchange module under dynamic fluctuations. It achieves flexible allocation of waste heat from processing equipment cooling water in the time dimension and rational distribution in the spatial dimension, improving the thermal energy utilization efficiency and heating continuity of the waste heat recovery device under unsteady operating conditions.

[0103] Optionally, the processes of steps 401 to 403 include: Step 401: Control the domestic water to flow through the independent heat exchange unit of domestic water and the intermediate heat exchange medium flowing to the independent heat exchange unit of domestic water in the intermediate heat exchange medium flow path for indirect isolation heat exchange. Monitor the outlet temperature of domestic water in real time. Based on the deviation between the outlet temperature and the preset target temperature, adjust the inlet flow rate of domestic water so that the outlet temperature of domestic water is stabilized at the preset target temperature, and obtain the target domestic water.

[0104] Optionally, the waste heat recovery device controls the flow of domestic water through an independent heat exchange unit, where it indirectly exchanges heat with the intermediate heat exchange medium flowing within the unit. Heat transfer between the domestic water and the intermediate heat exchange medium occurs through a metal wall, without direct contact. The waste heat recovery device monitors the outlet temperature of the domestic water in real time using a temperature sensor installed at the outlet of the independent heat exchange unit. The device compares the outlet temperature of the domestic water with a preset target temperature to obtain the deviation value between the two.

[0105] When the deviation value is positive (i.e. the outlet temperature is higher than the preset target temperature), the waste heat recovery device increases the inlet flow rate of domestic water, thereby increasing the amount of domestic water flowing through the independent heat exchange unit of domestic water per unit time, reducing the heat absorbed by each unit volume of domestic water, and lowering the outlet temperature.

[0106] When the deviation value is negative (i.e. the outlet temperature is lower than the preset target temperature), the waste heat recovery device reduces the inlet flow rate of domestic water, thereby reducing the amount of domestic water flowing through the independent heat exchange unit of domestic water per unit time, increasing the heat absorbed by each unit volume of domestic water, and raising the outlet temperature.

[0107] By continuously adjusting the inlet flow rate of domestic water, the outlet temperature of domestic water is stabilized at the preset target temperature, thus obtaining the target domestic water.

[0108] Continuing with the intermediate heat exchange medium flow path obtained in step 30 above, 4 cubic meters per hour of intermediate heat exchange medium at a temperature of 42 degrees Celsius flows to the independent domestic water heat exchange unit through the first outlet of the three-way regulating valve. Domestic water at a temperature of 15 degrees Celsius enters the independent domestic water heat exchange unit at an inlet flow rate of 2 cubic meters per hour. The temperature sensor at the outlet of the independent domestic water heat exchange unit detects an outlet temperature of 47 degrees Celsius, with a preset target temperature of 45 degrees Celsius and a deviation of ±2 degrees Celsius. Based on the ±2 degree Celsius deviation, the waste heat recovery device increases the inlet flow rate of the domestic water from 2 cubic meters per hour to 2.5 cubic meters per hour. After adjustment, the temperature sensor at the outlet of the independent domestic water heat exchange unit detects an outlet temperature of 45 degrees Celsius, consistent with the preset target temperature, with a deviation of 0 degrees Celsius. The domestic water at this point, with a temperature of 45 degrees Celsius, is the target domestic water.

[0109] Step 402: Based on the real-time pressure difference between the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module, under the premise of meeting the minimum safe flow threshold, the opening of the electric regulating valve is controlled to adjust the flow velocity of the main cooling water in the three-stage phase change heat transfer module to maintain it above the critical flow velocity for the transition from laminar to turbulent flow, so that the main cooling water maintains a turbulent heat transfer state in the cooling water channel of the three-stage phase change heat transfer module.

[0110] Optionally, the waste heat recovery device controls the opening of the electric regulating valve based on the real-time pressure difference between the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module, adjusting the flow velocity of the main cooling water within the module to maintain it above the critical velocity for the transition from laminar to turbulent flow. The critical velocity for the transition from laminar to turbulent flow is the minimum flow velocity required for the main cooling water to transition from laminar to turbulent flow within the cooling water channel of the three-stage phase change heat transfer module.

[0111] When the flow velocity of the main cooling water exceeds the critical velocity, the main cooling water is in a turbulent heat transfer state within the cooling water channel. The intense mixing of fluid particles in the turbulent state results in a significantly higher heat transfer coefficient than in the laminar flow state. When adjusting the opening of the electric regulating valve, the waste heat recovery device must simultaneously meet the constraint that the main cooling water flow rate is not lower than the preset minimum safe flow threshold of 4 cubic meters per hour.

[0112] The waste heat recovery device uses a differential pressure sensor to collect the real-time pressure difference between the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module. This real-time pressure difference reflects the flow resistance of the main cooling water within the cooling water channel, and there is a positive correlation between flow resistance and flow velocity. When the real-time pressure difference decreases, it indicates a decrease in flow velocity, and the waste heat recovery device increases the opening of the electric regulating valve to increase the flow velocity. When the real-time pressure difference increases, it indicates an increase in flow velocity, and the waste heat recovery device maintains the current opening or appropriately decreases the opening.

[0113] In one embodiment, a differential pressure sensor collects a real-time differential pressure of 12 kPa at the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module. Assuming the baseline differential pressure in the cooling water channel of the three-stage phase change heat transfer module under clean conditions is 10 kPa, and the critical differential pressure corresponding to the critical flow velocity transitioning from laminar to turbulent flow is 8 kPa, the current real-time differential pressure of 12 kPa is higher than the critical differential pressure of 8 kPa. This indicates that the flow velocity of the main cooling water in the cooling water channel of the three-stage phase change heat transfer module is higher than the critical flow velocity transitioning from laminar to turbulent flow, and the main cooling water is in a turbulent heat transfer state. The current main cooling water flow rate is 8 cubic meters per hour, which is higher than the preset minimum safe flow rate threshold of 4 cubic meters per hour, satisfying the lower flow limit constraint, and maintaining the current 65% opening of the electric regulating valve.

[0114] Step 403: Monitor the real-time pressure difference between the inlet and outlet of the cooling water side when the three-stage phase change heat transfer module is running under turbulent heat transfer conditions. When the real-time pressure difference exceeds the preset clean operating condition reference pressure difference threshold, control the backwash pump in the self-cleaning backwash pipeline to start and perform reverse high-pressure fluid flushing on the cooling water flow channel of the three-stage phase change heat transfer module.

[0115] Optionally, the waste heat recovery device monitors the real-time pressure difference between the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module during turbulent heat transfer. When the real-time pressure difference exceeds the preset clean operating condition reference pressure difference threshold, it indicates that dirt has adhered to the inner wall of the cooling water channel of the three-stage phase change heat transfer module, resulting in increased flow resistance and a higher pressure difference. At this time, the backwash pump in the self-cleaning backwash pipeline is activated to perform reverse high-pressure fluid flushing on the cooling water channel of the three-stage phase change heat transfer module. Reverse high-pressure fluid flushing means that the backwash pump injects high-pressure fluid from the outlet end of the cooling water channel of the three-stage phase change heat transfer module, causing the fluid to flow through the cooling water channel in the opposite direction to normal operation, flushing and peeling off the dirt adhering to the inner wall of the channel and discharging it from the inlet end of the cooling water channel. The preset clean operating condition reference pressure difference threshold is the pressure difference between the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module when operating at the current flow rate in a clean state.

[0116] In one embodiment, a differential pressure sensor continuously monitors the real-time differential pressure at the inlet and outlet of the cooling water side of the three-stage phase change heat exchange module during turbulent heat exchange. Assuming that after a period of operation, the real-time differential pressure increases from 12 kPa to 15 kPa, and the preset clean operating condition reference differential pressure threshold is 10 kPa, a real-time differential pressure of 15 kPa exceeds the preset clean operating condition reference differential pressure threshold of 10 kPa, indicating that dirt has adhered to the inner wall of the cooling water channel. The backwash pump in the self-cleaning backwash pipeline is then activated, injecting high-pressure fluid at a pressure of 0.5 MPa from the outlet end of the cooling water channel of the three-stage phase change heat exchange module. The high-pressure fluid flows through the cooling water channel in the opposite direction to normal operation, flushing away the dirt adhering to the inner wall of the channel. After 30 seconds of backwashing, the waste heat recovery device shuts off the backwash pump, restoring normal heat exchange operation.

[0117] The embodiments of the present invention work synergistically from three dimensions: ensuring heat supply quality, maintaining heat exchange flow, and cleaning heat exchange interfaces. This enables the system to maintain efficient and stable heat exchange performance throughout long-term operation, improves the recovery efficiency of waste heat from cooling water in processing equipment under dynamic fluctuation conditions, and enhances the long-term stability of the system.

[0118] Furthermore, the waste heat recovery and utilization device for cooling water of processing equipment provided by the present invention will be described below. The waste heat recovery and utilization device for cooling water of processing equipment described below can be referred to in correspondence with the waste heat recovery and utilization method for cooling water of processing equipment described above.

[0119] Optionally, refer to Figure 2 , Figure 2 This is a structural diagram of the waste heat recovery and utilization device for cooling water of processing equipment provided by the present invention. The waste heat recovery and utilization device for cooling water of processing equipment includes: The electric valve control module 210 is used to drive the opening of the electric regulating valve in the cooling water diversion assembly based on the inlet pressure of the cooling water return pipe, and to regulate the main cooling water flow rate entering the three-stage phase change heat transfer module so that the main cooling water flow rate is not lower than the preset minimum safe flow rate threshold, thereby obtaining the main cooling water.

[0120] The first heat exchange control module 220 is used to control the main cooling water to flow sequentially through the first sensible heat precooling section, the second embedded finned phase change section, and the third sensible heat cryogenic section of the three-stage phase change heat exchange module, and to exchange heat with the intermediate heat exchange medium circulating in the closed loop in a counter-current heat exchange, transferring the heat of the main cooling water to the intermediate heat exchange medium, so that the main cooling water is cooled down and discharged, and the intermediate heat exchange medium is heated to obtain the target intermediate heat exchange medium.

[0121] The second heat exchange control module 230 is used to drive the three-way regulating valve in the outlet pipeline of the phase change heat storage buffer tank based on the deviation between the outlet temperature of the target intermediate heat exchange medium after it flows into the phase change heat storage buffer tank and the phase change temperature of the phase change material, so as to adjust the ratio of the flow rate of the target intermediate heat exchange medium to the independent heat exchange unit of domestic water to the recirculation flow rate back to the inlet of the three-stage phase change heat exchange module, and obtain the flow path of the intermediate heat exchange medium.

[0122] The third heat exchange control module 240 is used to perform indirect isolation heat exchange based on the intermediate heat exchange medium flowing to the independent heat exchange unit of domestic water in the intermediate heat exchange medium flow path, so as to realize the recovery and utilization of waste heat of cooling water.

[0123] This invention achieves full-process coordinated operation by controlling the flow at the front end, optimizing the heat exchange in the middle stage, and optimizing the heat buffer operation at the back end. Through the closed-loop coordination of flow regulation, phase change heat exchange in the middle stage, and temperature feedback diversion and recirculation, it realizes the active maintenance of the flow state at the heat exchange interface and the precise matching of the heat energy grade in the tiers. This improves the recovery efficiency of waste heat from the cooling water of the processing equipment under dynamic fluctuation conditions and the stability of the system in long-term operation.

[0124] Please see Figure 3 , Figure 3 An embodiment diagram of an electronic device provided in accordance with the present invention. For example... Figure 3 As shown, an embodiment of the present invention provides an electronic device 300, including a memory 310, a processor 320, and a computer program 311 stored in the memory 310 and executable on the processor 320. When the processor 320 executes the computer program 311, it implements the processes of steps 10 to 40.

[0125] Please see Figure 4 , Figure 4 An embodiment diagram of a computer-readable storage medium provided in accordance with an embodiment of the present invention is shown. Figure 4As shown, this embodiment provides a computer-readable storage medium 400, on which a computer program 311 is stored. When the computer program 311 is executed by a processor, it implements the processes of steps 10 to 40.

[0126] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the waste heat recovery and utilization method for cooling water of the processing equipment provided by the above methods, which includes the process of steps 10 to 40.

[0127] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering and utilizing waste heat from cooling water in processing equipment, applied to a waste heat recovery device comprising a cooling water diversion assembly, a three-stage phase change heat exchange module, a phase change heat storage buffer tank, and an independent heat exchange unit for domestic water, characterized in that, The method includes: The opening of the electric regulating valve in the cooling water diversion component is driven by the inlet pressure of the cooling water return pipe, which regulates the flow rate of the main cooling water entering the three-stage phase change heat module, so that the flow rate of the main cooling water is not lower than the preset minimum safe flow rate threshold, thus obtaining the main cooling water. The main cooling water flows sequentially through the first sensible heat precooling section, the second embedded fin phase change section, and the third sensible heat cryogenic section of the three-stage phase change heat exchange module. It exchanges heat with the intermediate heat exchange medium circulating in the closed loop in a counter-current manner, transferring the heat from the main cooling water to the intermediate heat exchange medium. This cools the main cooling water before it is discharged, and raises the temperature of the intermediate heat exchange medium to obtain the target intermediate heat exchange medium. Based on the deviation between the outlet temperature of the target intermediate heat exchange medium after it flows into the phase change heat storage buffer tank and the phase change temperature of the phase change material, the three-way regulating valve located in the outlet pipeline of the phase change heat storage buffer tank is driven to adjust the ratio of the flow rate of the target intermediate heat exchange medium to the independent heat exchange unit of domestic water to the recirculation flow rate back to the inlet of the three-stage phase change heat exchange module, so as to obtain the flow path of the intermediate heat exchange medium. Indirect isolation heat exchange is achieved by using the intermediate heat exchange medium flowing to the independent heat exchange unit of domestic water in the intermediate heat exchange medium flow path, so as to realize the recovery and utilization of waste heat of cooling water.

2. The method for recovering waste heat from cooling water in processing equipment according to claim 1, characterized in that, The waste heat recovery device also includes a self-cleaning backwashing pipeline; the indirect isolation heat exchange based on the intermediate heat exchange medium flowing to the independent heat exchange unit of domestic water in the intermediate heat exchange medium flow path includes: The system controls the flow of domestic water through an independent heat exchange unit and the intermediate heat exchange medium flowing into the independent heat exchange unit in the intermediate heat exchange medium flow path for indirect isolation heat exchange. The outlet temperature of the domestic water is monitored in real time. Based on the deviation between the outlet temperature and the preset target temperature, the inlet flow rate of the domestic water is adjusted so that the outlet temperature of the domestic water is stabilized at the preset target temperature, thus obtaining the target domestic water. Based on the real-time pressure difference between the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module, under the premise of meeting the minimum safe flow threshold, the opening of the electric regulating valve is controlled to adjust the flow velocity of the main cooling water in the three-stage phase change heat transfer module to maintain it above the critical flow velocity for the transition from laminar to turbulent flow, so that the main cooling water maintains a turbulent heat transfer state in the cooling water channel of the three-stage phase change heat transfer module. The real-time pressure difference between the inlet and outlet of the cooling water side of the three-stage phase change heat transfer module is monitored when it is running under turbulent heat transfer conditions. When the real-time pressure difference exceeds the preset benchmark pressure difference threshold, the backwash pump in the self-cleaning backwash pipeline is started to perform reverse high-pressure fluid flushing on the cooling water flow channel of the three-stage phase change heat transfer module.

3. The method for recovering and utilizing waste heat from cooling water in processing equipment according to claim 1, characterized in that, The process of countercurrent heat exchange between the main cooling water and the intermediate heat exchange medium includes: The main cooling water is introduced into the tube-side flow channel of the first-stage sensible heat precooling section, and the target intermediate heat exchange medium is introduced into the shell-side flow channel of the first-stage sensible heat precooling section, so that the two form a counter-current convection arrangement in the flow direction. The sensible heat of the main cooling water is transferred to the target intermediate heat exchange medium by utilizing the thermal conductivity of the metal wall in the first-stage sensible heat precooling section, thereby reducing the temperature of the main cooling water to above the starting temperature point of the phase change material undergoing solid-liquid phase transformation. The main cooling water, which has been pre-cooled by sensible heat, is introduced into the flow channel of the second-stage embedded fin phase change section, so that the main cooling water and the phase change material filled in the cavity of the second-stage embedded fin phase change section can be transferred through contact heat transfer via embedded high thermal conductivity fins. The driving phase change material absorbs the heat released by the main cooling water and undergoes a change of state, thus completing the countercurrent heat exchange between the main cooling water and the intermediate heat exchange medium.

4. The method for recovering and utilizing waste heat from cooling water in processing equipment according to claim 3, characterized in that, The driving phase change material absorbs the heat released by the main cooling water and undergoes a phase change, completing the countercurrent heat exchange between the main cooling water and the intermediate heat exchange medium, including: The driving phase change material absorbs the heat released by the main cooling water and undergoes a change of state. During the phase change material's completion of the change of state, the temperature of the intermediate heat exchange medium on the outlet side of the second-stage embedded fin phase change section remains constant. The main cooling water that flows through the second-stage embedded fin phase change section is transported to the third-stage sensible heat cryogenic section, where the low-temperature intermediate heat exchange medium in the third-stage sensible heat cryogenic section absorbs the residual sensible heat in the main cooling water. After completing the three-stage heat exchange, the main cooling water is discharged from the third-stage sensible heat cryogenic section, and the intermediate heat exchange medium that has absorbed all the heat is collected and transported to the inlet of the phase change heat storage buffer tank.

5. The method for recovering and utilizing waste heat from cooling water in processing equipment according to claim 1, characterized in that, The operational decoupling process between the first-stage sensible heat precooling section and the second-stage embedded fin phase change section includes: Based on the comparison between the real-time outlet temperature of the intermediate heat exchange medium at the outlet side of the second-stage embedded fin phase change section and the liquidus characteristic temperature corresponding to the complete melting of the phase change material in the second-stage embedded fin phase change section, it is determined whether the phase change material in the second-stage embedded fin phase change section has completed the solid-liquid phase transformation. Once it is determined that the phase change material has completed the solid-liquid phase transition, the interstage isolation shut-off valve on the pipeline between the outlet of the first-stage sensible heat precooling section and the inlet of the second-stage embedded fin phase change section is closed, cutting off the flow path of the main cooling water from the first-stage sensible heat precooling section to the second-stage embedded fin phase change section. The bypass switching valve at the inlet of the cross-stage bypass pipeline at the outlet of the first-stage sensible heat precooling section is opened, and the main cooling water discharged from the first-stage sensible heat precooling section is introduced into the cross-stage bypass pipeline, so that the main cooling water bypasses the second-stage embedded fin phase change section. The main cooling water in the bypass pipeline is controlled to flow into the inlet pipe section of the third-stage sensible heat cryogenic section, so that the main cooling water can continue to complete cryogenic heat exchange while skipping the second-stage embedded fin phase change section. Close the inlet and outlet valves on the cooling water side of the second-stage embedded finned phase change section, as well as the inlet and outlet valves on the intermediate heat exchange medium side, so that the second-stage embedded finned phase change section enters a closed heat storage state, sealing the absorbed latent heat of phase change inside the phase change material.

6. The method for recovering waste heat from cooling water in processing equipment according to claim 1, characterized in that, The operational decoupling process between the second-stage embedded fin phase change section and the third-stage sensible heat cryogenic section includes: If the current phase state information of the phase change material in the inner cavity of the second-stage embedded fin phase change section indicates that the phase change material changes from liquid to solid and releases the stored latent heat of phase change to the outside, it is determined that the second-stage embedded fin phase change section has entered the solidification regeneration exothermic condition. The interstage isolation shut-off valve on the pipeline between the outlet of the second-stage embedded fin phase change section and the inlet of the third-stage sensible heat cryogenic section is closed, and the flow path of the main cooling water from the second-stage embedded fin phase change section to the third-stage sensible heat cryogenic section is cut off. Close the connecting valve on the intermediate heat exchange medium side between the second-stage embedded fin phase change section and the third-stage sensible heat cryogenic section, cut off the flow path of the intermediate heat exchange medium between the two stages, so that the second-stage embedded fin phase change section and the third-stage sensible heat cryogenic section achieve flow isolation on both the cooling water side and the intermediate heat exchange medium side. Open the conduction valve in the regeneration heat release pipeline from the outlet of the intermediate heat exchange medium side of the second-stage embedded finned phase change section to the phase change heat storage buffer tank, and drive the latent heat released by the solidification of the phase change material in the second-stage embedded finned phase change section to be input into the phase change heat storage buffer tank for storage through the regeneration heat release pipeline. Open the bypass valve in the cross-stage bypass pipeline connecting the outlet of the first-stage sensible heat precooling section and the inlet of the third-stage sensible heat cryogenic section, and directly transport the main cooling water discharged from the first-stage sensible heat precooling section to the inlet of the third-stage sensible heat cryogenic section through the cross-stage bypass pipeline, so that the continuous heat exchange of the main cooling water is uninterrupted.

7. The method for recovering waste heat from cooling water in processing equipment according to claim 1, characterized in that, The formation process of the intermediate heat exchange medium flow path for balanced heat energy distribution includes: Real-time temperature data of the intermediate heat exchange medium at the outlet of the phase change thermal storage buffer tank and the current phase state position information of the phase change material in the tank are collected. The real-time temperature data is compared with the characteristic temperature points corresponding to the complete melting or solidification of the phase change material to determine the current heat carrying capacity of the intermediate heat exchange medium. The valve core displacement command of the three-way regulating valve is generated based on the heat carrying capacity status; the valve core displacement command indicates a change in the ratio of the connecting cross-sectional area of ​​the internal flow channel of the three-way regulating valve. The first intermediate heat exchange medium is controlled to flow to the independent heat exchange unit for domestic water through the first outlet of the three-way regulating valve as an external heating branch, and the remaining second intermediate heat exchange medium is controlled to flow back to the inlet of the three-stage phase change heat exchange module through the second outlet of the three-way regulating valve as an internal heat circulation branch. Based on the valve core displacement command, the flow cross-sectional area ratio of the external heating branch and the internal heat circulation branch is adjusted so that the sum of the mass flow rates of the intermediate heat exchange medium in the external heating branch and the internal heat circulation branch is equal to the total discharge flow rate of the phase change heat storage buffer tank, thereby completing the distribution of heat energy between the external load and the internal heat storage and release.

8. A device for recovering and utilizing waste heat from cooling water in processing equipment, characterized in that, A device for implementing the waste heat recovery and utilization method of cooling water in processing equipment as described in any one of claims 1 to 7; the device comprises: The electric valve control module is used to drive the opening of the electric regulating valve in the cooling water diversion component based on the inlet pressure of the cooling water return pipe, and adjust the main cooling water flow rate entering the three-stage phase change heat transfer module so that the main cooling water flow rate is not lower than the preset minimum safe flow rate threshold, thus obtaining the main cooling water. The first heat exchange control module is used to control the main cooling water to flow sequentially through the first sensible heat precooling section, the second embedded fin phase change section and the third sensible heat cryogenic section of the three-stage phase change heat exchange module, and to exchange heat with the intermediate heat exchange medium circulating in the closed loop in a counter-current heat exchange, transferring the heat of the main cooling water to the intermediate heat exchange medium, so that the main cooling water is cooled down and discharged, and the intermediate heat exchange medium is heated to obtain the target intermediate heat exchange medium. The second heat exchange control module is used to drive a three-way regulating valve located in the outlet pipeline of the phase change heat storage buffer tank based on the deviation between the outlet temperature of the target intermediate heat exchange medium after it flows into the phase change heat storage buffer tank and the phase change temperature of the phase change material. This regulates the ratio of the flow rate of the target intermediate heat exchange medium to the independent heat exchange unit of domestic water to the recirculation flow rate back to the inlet of the three-stage phase change heat exchange module, thus obtaining the flow path of the intermediate heat exchange medium. The third heat exchange control module is used to perform indirect isolation heat exchange based on the intermediate heat exchange medium flowing to the independent heat exchange unit of domestic water in the intermediate heat exchange medium flow path, so as to realize the recovery and utilization of waste heat of cooling water.

9. An electronic device, comprising: A memory for storing a computer program; a processor for reading and executing the computer program, characterized in that, when the processor executes the computer program, it implements the waste heat recovery and utilization method for cooling water of processing equipment as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the waste heat recovery and utilization method of cooling water for processing equipment as described in any one of claims 1 to 7.

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