Modular heat storage tank based on high-thermal-conductivity composite phase-change material and cooperative control method of modular heat storage tank

Abstract

The invention discloses a modular heat storage tank based on a high-thermal-conductivity composite phase change material and a cooperative control method of the modular heat storage tank. The heat storage tank comprises a tank body shell, a heat conduction module, a water distribution assembly, a monitoring module, a spring type pressure release valve and a pressure sensor. The tank shell is horizontally arranged in the axial direction, a cavity is formed in the tank shell, the two ends of the cavity are each provided with a water distribution assembly, a space defined by the water distribution assemblies at the two ends and the inner side wall of the tank shell serves as a heat conduction module area, and a plurality of heat conduction modules are arranged in the heat conduction module area at intervals in the axial direction. A plurality of monitoring modules are installed on the inner side wall of the tank body shell, a spring type pressure release valve and a pressure sensor are installed on the outer side wall of the tank body shell, and the tank body shell is outwards connected with a water pump; the method comprises a heat charging mode, a heat releasing mode and a heat preservation mode for adjusting the water flow speed according to the water flow temperature. The high thermal conductivity of the PCM is realized, the utilization rate of the PCM is effectively increased, the heat release power curve is leveled, and the high-temperature heat release time is prolonged.

Description

Technical Field

[0001] This invention relates to the field of thermal energy storage technology, specifically to a modular thermal storage tank based on a high thermal conductivity composite phase change material and its collaborative control method. Background Technology

[0002] In the field of thermal energy storage technology, phase change materials (PCMs) are the core carriers for achieving efficient heat storage and release. Through the phase change process between solid and liquid states, they absorb or release a large amount of latent heat and can complete energy storage and output at a near constant temperature. They are the key medium connecting intermittent energy sources (such as solar energy), industrial waste heat and user heat demand. Using a heat storage tank as the carrier and heat exchange container of the PCM is the core structure for realizing a closed loop of heat input-storage-output. Its design rationality directly determines the efficiency of PCM performance and the stability of system operation.

[0003] However, the current PCM phase change materials and modular thermal storage tank technology have the following shortcomings: 1. Existing phase change heat storage tanks generally suffer from a sharp drop in heat exchange power in the later stages of heat release due to increased thermal resistance of the solidification layer and weakened natural convection, resulting in a large amount of latent heat remaining unused in the tank. 2. Conventional PCM materials (such as pure hydrated salts and paraffin) have low thermal conductivity, which is the main reason why a large amount of latent heat cannot be utilized in the tank. Although this can be improved by using thermally conductive fillers, they often have problems such as uneven distribution, poor compatibility with PCM, and poor long-term stability. 3. Existing heat storage tanks have simple structures and uneven water flow distribution, which easily creates dead zones, causing some PCMs to be unable to participate in heat exchange; 4. Existing operating strategies are crude, usually involving only a simple constant flow rate for charging and discharging heat, which cannot adapt to changes in the internal state of the heat storage tank, resulting in low efficiency.

[0004] Therefore, based on the aforementioned technical problems, it is necessary to design a modular heat storage tank system to improve the latent heat utilization rate and heat release rate stability of phase change materials (PCM). Summary of the Invention

[0005] To achieve the aforementioned objectives of improving the latent heat utilization rate of the PCM, maintaining the output power in the later stages of the heat release process, and extending the usable heat release time, the present invention provides the following technical solution: I. A modular thermal storage tank based on a high thermal conductivity composite phase change material The device includes a tank shell, a heat conduction module, a water distribution assembly, a monitoring module, a spring-loaded pressure relief valve, and a pressure sensor. The tank shell is horizontally placed axially and has an internal cavity. A water distribution assembly is installed at each end of the cavity. The space enclosed by the water distribution assemblies and the inner wall of the tank shell serves as the heat conduction module area. Multiple heat conduction modules are arranged axially at intervals within the heat conduction module area. Multiple monitoring modules are installed on the inner wall of the tank shell, and a spring-loaded pressure relief valve and a pressure sensor are installed on the outer wall of the tank shell. One end of the tank shell is connected to a water pump via a water pipe, and the other end is connected to a heat exchanger via a water pipe.

[0006] Each heat-conducting module comprises an aluminum encapsulation shell, a heat dissipation fin assembly, and a porous framework matrix. The aluminum encapsulation shell is a plate-like structure with an internal cavity. The porous framework matrix is ​​arranged within the internal cavity. Through-hole arrays are formed on both ends of the aluminum encapsulation shell. Each end face of the aluminum encapsulation shell has multiple rows of through-hole arrays. The heat dissipation fin assembly includes multiple rows of heat dissipation fin arrays. The through-hole arrays and heat dissipation fin arrays are alternately arranged along the same direction on each end face of the aluminum encapsulation shell. Each heat dissipation fin is inclined relative to the radial plane of the aluminum encapsulation shell to extend the water flow path. The porous framework matrix is ​​a composite structure of expanded graphite and PCM phase change material. The PCM phase change material is one of inorganic hydrated salts, organic paraffin, or fatty acids.

[0007] Both ends of each heat-conducting module are fixedly connected to the corresponding inner sidewall of the tank shell by a metal bracket. The gap between each two adjacent heat-conducting modules is divided into three partition channels by three metal plates evenly distributed in the circumference, so that the water flows axially in the partition channels. The partition channels are used to separate the water flowing through the inside of the heat storage tank.

[0008] The water distribution assembly includes a first porous circular plate installed near one end of the tank shell and a second porous circular plate installed near the other end of the tank shell. Each of the first and second porous circular plates has multiple axially through-type diversion channels. A water pump is connected to the end of the tank shell where the first porous circular plate is installed, and a heat exchanger is connected to the end of the tank shell where the second porous circular plate is installed.

[0009] The water flow direction inside the tank shell is from the end where the first porous circular plate is installed to the other end where the second porous circular plate is installed. The arrangement of the heat-conducting modules in the heat-conducting module area is such that the phase change temperature of the PCM phase change material in the heat-conducting module decreases sequentially from the water flow direction, thereby forming a high phase change temperature zone near the water inlet, a medium phase change temperature zone in the middle, and a low phase change temperature zone near the water outlet.

[0010] The monitoring module consists of a first temperature sensor, a second temperature sensor, and a third temperature sensor. A first temperature sensor is installed on the inner wall of the tank's inlet end to collect the temperature of the water flow at the inlet end as the inlet temperature. A second temperature sensor is installed on the inner wall of the outlet end to collect the temperature of the water flow at the outlet end as the outlet temperature. A third temperature sensor is installed on the inner wall of the tank's outer shell within each of the partition channels to collect the water flow temperature passing through the high phase change temperature zone, the medium phase change temperature zone, and the low phase change temperature zone, thereby obtaining the temperatures of the high phase change temperature zone, the medium phase change temperature zone, and the low phase change temperature zone. The average of these three temperatures is then used to obtain the average temperature of each zone within the tank. The inner wall of the tank's outer shell is lined with a rock wool insulation layer. A spring-loaded pressure relief valve and a pressure sensor for sensing pressure are fixedly installed on the same side of the outer wall of the tank's outer shell.

[0011] II. A Collaborative Control Method for Modular Thermal Storage Tanks Made of High Thermal Conductivity Composite Phase Change Materials The control method includes: It has three modes: heat charging mode, heat dissipation mode, and heat preservation mode. 1) Heat charging mode: When the average temperature of each zone in the tank is lower than the first preset temperature, the water pump is turned on, so that the water flows in the heat storage tank. When the water flows through the heat conduction module, the PCM phase change material in the heat conduction module is charged with heat. Based on the PCM phase change material with different phase change temperatures in the axial direction, heat is stored in layers. At the same time, the water flow rate is controlled by the water pump. The specific steps of step 1) heat charging mode coordinated control are as follows: Real-time comparison of temperatures in the high phase transition temperature zone, low phase transition temperature zone, and medium phase transition temperature zone with the second preset temperature: If the temperatures in the high phase change temperature zone, low phase change temperature zone, and medium phase change temperature zone are all lower than the third preset temperature, the water pump will maintain a fixed water flow rate to ensure water flow. If the temperature in the high phase change temperature zone is not less than the third preset temperature, and the temperatures in the low phase change temperature zone and the medium phase change temperature zone are all lower than the third preset temperature, the water pump will reduce the water flow rate. If the temperatures in the high phase change temperature zone and the low phase change temperature zone are not lower than the third preset temperature, and the temperature in the medium phase change temperature zone is lower than the third preset temperature, the water pump will further reduce the flow rate. If the temperatures in the high phase change temperature zone, low phase change temperature zone, and medium phase change temperature zone are all not lower than the third preset temperature and are maintained for a certain period of time, the water pump will stop and switch to the heat preservation mode.

[0012] 2) Heat preservation mode: After step 1) heat charging mode, when the average temperature of each zone in the tank rises to between the first preset temperature and the second preset temperature, the water pump stops, so that the water flow in the heat storage tank stops. 3) Heat release mode: When the average temperature of each zone in the tank rises to a level greater than the second preset temperature, the water pump is turned on. When the water flows through the heat conduction module, the PCM phase change material in the heat conduction module releases heat. Based on the PCM phase change materials with different phase change temperatures along the axis, heat is released in layers. The flow rate and temperature are coordinated by using PID closed-loop optimization to optimize the water flow rate through the water pump.

[0013] Step 3) of the heat release mode coordinated control specifically involves: Using the outlet temperature as the core feedback signal, the water flow rate is set via the water pump: If the outlet temperature is not lower than the fourth preset temperature, the water pump will increase the flow rate. If the outlet temperature is not greater than the fifth preset temperature, the water pump will reduce the flow rate. If the outlet temperature is between the fourth and fifth preset temperatures, the water pump will maintain the current flow rate. The PID closed-loop optimization specifically involves: By inputting the difference between the outlet temperature and the fifth preset temperature, and the water flow rate, and then supplementing the quantitative value based on conventional thermal storage system debugging experience, the pump speed is adjusted through PID calculation output results.

[0014] The control method handles fault conditions in the following manner: If the third temperature sensor fails, the average value of other third temperature sensors in the same area will be used to replace the data at that point. If the second temperature sensor fails, the outlet temperature will be temporarily replaced by the temperature in the low phase change temperature zone. If the first temperature sensor fails, the temperature in the high phase change temperature zone will be used temporarily to replace the inlet temperature. If the pressure sensor detects that the pressure is lower than the first preset pressure value, the water pump will maintain a normal flow rate. If the pressure sensor detects that the pressure is at the first preset pressure value and the second preset pressure value, the water pump will reduce the flow rate. If the pressure sensor detects that the pressure is greater than the second preset pressure value, the spring-loaded pressure relief valve will open to release pressure, and the water pump will stop working.

[0015] Compared with existing technologies, this invention provides a modular thermal storage tank based on a high thermal conductivity composite phase change material and its synergistic control method, which has the following beneficial effects: 1. The modular thermal storage tank based on high thermal conductivity composite phase change material and its collaborative control method form an efficient heat conduction network through an expanded graphite skeleton, effectively reducing the thermal resistance of the solidified layer and enabling the rapid release of latent heat, thus achieving high thermal conductivity of the PCM. At the same time, the regular arrangement of PCM modules is combined with an efficient water distribution system to ensure the uniformity of water flow and heat exchange, avoid the existence of heat exchange dead zones, and effectively improve the utilization rate of PCM.

[0016] 2. The modular heat storage tank based on high thermal conductivity composite phase change material and its collaborative control method effectively solve the problems of phase separation, overcooling and leakage of PCM through standardized composite and metal encapsulation. Its modular structure facilitates production, transportation and installation and maintenance. In case of damage, it is convenient to quickly replace individual modules. At the same time, the intelligent variable flow control strategy can adaptively adjust the operating status, effectively flatten the heat release power curve and extend the high temperature heat release time. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the heat storage tank of the present invention; Figure 2 This is a schematic diagram of the partition channel structure of the present invention; Figure 3 This is a schematic diagram of the structure of a single heat-conducting module of the present invention; Figure 4 This is a schematic diagram showing the arrangement of the heat-conducting modules inside the tank according to the present invention; Figure 5 This is a block diagram of the control system principle of the present invention.

[0018] In the diagram: 1. Tank shell; 2. Heat conduction module; 201. Aluminum encapsulation shell; 202. Heat dissipation fin assembly; 203. Porous skeleton matrix; 3. Water distribution assembly; 301. First porous circular plate; 302. Second porous circular plate; 4. Monitoring module; 401. First temperature sensor; 402. Second temperature sensor; 403. Third temperature sensor; 5. Isolation channel; 6. Metal bracket; 7. Rock wool insulation layer; 8. Spring-loaded pressure relief valve; 9. Pressure sensor. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and 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.

[0021] like Figure 1As shown, the heat storage tank includes a tank shell 1, a heat conduction module 2, a water distribution assembly 3, a monitoring module 4, a spring-loaded pressure relief valve 8, and a pressure sensor 9. The tank shell 1 is horizontally placed along the axis and has an internal cavity. A water distribution assembly 3 is installed at each end of the cavity. The space enclosed by the water distribution assemblies 3 at both ends and the inner wall of the tank shell 1 serves as the heat conduction module area. Multiple honeycomb-shaped heat conduction modules 2 are arranged at intervals along the axis of the tank shell 1 within the heat conduction module area. All water distribution assemblies 3 and heat conduction modules 2 are perpendicular to the axis. Multiple monitoring modules 4 are installed on the inner wall of the tank shell 1, and a spring-loaded pressure relief valve 8 and a pressure sensor 9 are installed on the outer wall of the tank shell 1. The pressure sensor 9 and all monitoring modules 4 are connected to a controller. One end of the tank shell 1 is connected to a water pump via a water pipe, and the other end is connected to a heat exchanger via a water pipe. Specifically, both ends of the tank shell 1 have a cross-sectional dimension that gradually decreases from the inside to the outside. After the water flows in from the smaller outer part, the water flow speed is slowed down, so that the water flow and the heat conduction module 2 can exchange heat fully.

[0022] like Figure 3 As shown, a single heat-conducting module 2 includes an aluminum encapsulation shell 201, a heat dissipation fin assembly 202, and a porous skeleton matrix 203. The aluminum encapsulation shell 201 is a plate-like structure with an inner cavity. The porous skeleton matrix 203 is arranged inside the inner cavity. Through-hole arrays are respectively formed on both ends of the aluminum encapsulation shell 201, and the through-holes on each end face are arranged in a honeycomb structure. The through-hole array on each end face of the aluminum encapsulation shell 201 includes multiple rows of through-holes. The heat dissipation fin assembly 202 includes multiple rows of through-holes. The heat dissipation fin array, the through-hole array, and the heat dissipation fin array are arranged alternately along the same direction on each end face of the aluminum encapsulation shell 201, such that there is a through-hole between every two heat dissipation fins in this direction. Each heat dissipation fin is inclined at 75° outward relative to the radial plane of the aluminum encapsulation shell 201 to extend the water flow path. Specifically, the surface of the aluminum encapsulation shell 201 is uniformly distributed with heat dissipation fin groups 202 with a 15° slope through a welding process.

[0023] The porous framework matrix 203 is a composite structure of expanded graphite and PCM phase change material. The PCM phase change material is one of inorganic hydrated salt, organic paraffin or fatty acid.

[0024] like Figure 2 and Figure 4As shown, both ends of each heat-conducting module 2 are fixedly connected to the corresponding inner sidewall of the tank shell 1 via metal brackets 6. Preferably, the spacing between two adjacent metal brackets 6 is 10mm. The gap between each pair of adjacent heat-conducting modules 2 is divided into three uniform partition channels 5 by three radially spaced metal plates parallel to the axial direction of the tank shell 1, so that the water flows axially within the partition channels 5. Specifically, each of the three metal plates is fixedly connected to each other at the axial position of the tank shell 1 through one end, and the three metal plates are then fixedly connected to the inner sidewall of the tank shell 1 through their other ends. The partition channels 5 are used to separate the water flowing through the inside of the heat storage tank.

[0025] The water distribution assembly 3 includes a first porous circular plate 301 installed near one end of the tank shell 1 and a second porous circular plate 302 installed near the other end of the tank shell 1. The first porous circular plate 301 and the second porous circular plate 302 each have multiple axially through-structured diversion channels. A water pump is connected to the end of the tank shell 1 where the first porous circular plate 301 is installed, and a heat exchanger is connected to the end of the tank shell 1 where the second porous circular plate 302 is installed. The water flow direction inside the tank shell 1 is from the end where the first porous circular plate 301 is installed to the end where the second porous circular plate 302 is installed. The arrangement of the heat-conducting modules 2 in the heat-conducting module area is arranged in order of decreasing phase change temperature of the PCM phase change material in the heat-conducting module 2 from the water flow direction, thereby forming a high phase change temperature zone near the water inlet, a medium phase change temperature zone in the middle, and a low phase change temperature zone near the water outlet.

[0026] The monitoring module 4 is divided into a first temperature sensor 401, a second temperature sensor 402, and a third temperature sensor 403. The first temperature sensor 401 is installed on the inner wall of the inlet end of the tank shell 1 to collect the temperature of the water flow at the inlet end as the inlet temperature. The second temperature sensor 402 is installed on the inner wall of the outlet end to collect the temperature of the water flow at the outlet end as the outlet temperature. A third temperature sensor 403 is installed on the inner wall of the tank shell 1 within each compartment channel 5 to collect the temperature of the water flowing through the high phase change temperature zone, the medium phase change temperature zone, and the low phase change temperature zone, thereby obtaining... The average temperature of each zone inside the tank is obtained by averaging the temperatures of the high phase change temperature zone, the medium phase change temperature zone, and the low phase change temperature zone. The inner wall of the tank shell 1, including the inner end wall and the inner side wall, is covered with a rock wool insulation layer 7. The heat conduction module 2, the water distribution component 3, and the monitoring module 4 are all connected to the tank shell 1 through the rock wool insulation layer 7. An aluminum foil reflective layer is wrapped on the outside of the rock wool insulation layer 7. A spring-type pressure relief valve 8 for pressure relief and a pressure sensor 9 for sensing pressure are fixedly installed on the same side of the outer wall of the tank shell 1.

[0027] Control methods include: It has three modes: heat charging mode, heat dissipation mode, and heat preservation mode. 1) Heating Mode: When the average temperature of each zone inside the tank is lower than the first preset temperature, the water pump is turned on, causing water to flow inside the heat storage tank. The water temperature is higher than the temperature of the heat conduction module 2 inside the tank shell 1, so that when the water flows through the heat conduction module 2, the PCM phase change material inside the heat conduction module 2 is uniformly heated. The PCM phase change material, which is divided into zones based on different phase change temperatures along the axis, achieves layered heat storage. At the same time, the monitoring module 4 collects the corresponding data of its installed area and transmits it to the controller. The controller coordinates the water flow rate through the water pump based on the transmitted data. During heating, the heat conduction network formed by expanded graphite (EG) with a mass fraction of 15%-25% can effectively improve the heat conduction efficiency and avoid local overheating of the PCM. The heat dissipation fins are set at a height of 5-15mm, which increases the heat exchange area by 2-3 times and accelerates the heat introduction. The sealing structure combining welding and sealant ensures that the PCM is leak-free during long-term use.

[0028] Step 1) The coordinated control of the heat charging mode is specifically as follows: The controller compares the temperatures in the high phase change temperature zone, low phase change temperature zone, and medium phase change temperature zone with the second preset temperature in real time. If the temperatures of the high phase change temperature zone, the low phase change temperature zone, and the medium phase change temperature zone are all lower than the third preset temperature, i.e., the three zones have not reached the target, the controller controls the water pump to maintain a fixed water flow rate to ensure that the high-temperature water flow prioritizes heating the heat conduction module 2 in the high phase change temperature zone. If the temperature of the high phase change temperature zone is not less than the third preset temperature, and the temperatures of the low phase change temperature zone and the medium phase change temperature zone are all lower than the third preset temperature, that is, the inlet zone meets the standard, while the middle zone and the outlet zone do not meet the standard, the controller controls the water pump to reduce the water flow rate and extend the residence time of the water flow in the middle of the heat storage tank, so that the heat conduction module 2 in the middle phase change temperature zone can fully absorb heat. If the temperature of the high phase change temperature zone and the low phase change temperature zone are not less than the third preset temperature, and the temperature of the medium phase change temperature zone is lower than the third preset temperature, that is, the inlet zone and the middle zone meet the standard, but the outlet zone does not meet the standard, the controller controls the water pump to further reduce the flow rate and focus the water flow to continue heating the heat conduction module 2 in the low phase change temperature zone. If the temperatures in the high phase change temperature zone, low phase change temperature zone, and medium phase change temperature zone are all not lower than the third preset temperature, that is, if all three zones reach the target and remain at that temperature for a certain period of time, it is determined that the PCM phase change material is completely melted, i.e., the latent heat storage is saturated. The controller then controls the water pump to stop and switch to the heat preservation mode.

[0029] 2) Heat preservation mode: After step 1) heat charging mode, when the average temperature of each zone in the tank rises to between the first preset temperature and the second preset temperature, the water pumps at both ends stop, causing the water flow in the heat storage tank to stop. At the same time, the monitoring module 4 collects data and transmits it to the controller. During the heat preservation stage after heat charging, the heat preservation layer can effectively reduce the heat loss rate in the tank. The aluminum foil reflective layer reflects radiant heat, further reducing heat loss. If the PCM expands due to heat during heat charging, causing the pressure in the tank to exceed the opening pressure of the pressure relief valve, the pressure relief valve will automatically open to release pressure. The pressure sensor 9 monitors the pressure in real time. When the pressure rises abnormally, it triggers the controller to cut off the heat source and alarm to prevent the tank from cracking.

[0030] 3) Heat release mode: When the average temperature of each zone in the tank rises to a level higher than the second preset temperature, the water pump is turned on. The water flow temperature is lower than the temperature of the heat conduction module 2 inside the tank shell 1, so that when the water flows through the heat conduction module 2, the PCM phase change material in the heat conduction module 2 releases heat uniformly. The PCM phase change material, which is zoned based on different phase change temperatures along the axis, achieves heat stratification and maintains a stable outlet water temperature. At the same time, the monitoring module 4 collects the corresponding data of its installed area and transmits it to the controller. The controller uses PID closed-loop optimization to achieve flow-temperature coordinated control of the water flow rate through the water pump based on the transmitted data. During heat release, the low thermal resistance of expanded graphite EG can quickly release the latent heat of the deep PCM. The fins disturb the water flow and avoid the heat exchange power reduction caused by the accumulation of solidified layer.

[0031] Step 3) The coordinated control of the heat release mode is specifically as follows: The water flow rate is set by using the outlet temperature as the core feedback signal and the water pump. If the outlet temperature is not lower than the fourth preset temperature, the controller will control the water pump to increase the flow rate and speed up the water flow to remove heat, so as to avoid the outlet water temperature being too high. If the outlet temperature is not greater than the fifth preset temperature, the controller controls the water pump to reduce the flow rate, prolonging the heat exchange time between the water flow and the PCM phase change material in the heat conduction module 2, and releasing deep latent heat using the EG heat conduction network. If the outlet temperature is between the fourth and fifth preset temperatures (excluding both ends), the controller will control the water pump to maintain the current flow rate to ensure stable water temperature. After the water flows through the 2-5mm diameter holes on the first porous circular plate 301 and the second porous circular plate 302, the flow velocity is controlled at 0.3-0.8m / s to avoid excessively high flow velocity leading to a surge in resistance, or too low flow velocity leading to insufficient heat exchange. There is no local water flow concentration, and dead zone areas are completely eliminated. A flow channel width of 5-10mm is opened on the honeycomb porous heat-conducting module 2 to ensure that the water flow velocity is 0.3-0.8m / s, which avoids both poor laminar heat transfer and excessive turbulent resistance, reducing water pump energy consumption by about 10%-15%; the metal bracket 6 prevents the module from shifting and ensures the long-term stability of the flow channel network. During heat release, the water first exchanges heat with the PCM at 55-60℃ in the inlet area, maintaining the water temperature above 55℃; then it passes through the PCM at 50-55℃ in the middle area, where the water temperature drops to 50-55℃; finally, it passes through the PCM at 45-50℃ in the outlet area, where the water temperature stabilizes above 45℃, effectively extending the high-temperature output time. Radially distributed platinum resistance sensors can capture the temperature difference between the edge and center inside the tank, while the remaining platinum resistance sensors form a full-dimensional monitoring network, providing accurate data support for intelligent control.

[0032] The specific implementation steps for the modular thermal storage tank collaborative control method include: The first temperature sensor 401, the second temperature sensor 402 and the third temperature sensor 403 all adopt the PT100 platinum resistance sensing structure. The third temperature sensor 403 has three mounting points radially arranged inside each compartment channel 5.

[0033] The platinum resistance sensor acquires temperature data at a frequency of 10 seconds per acquisition, specifically including: 1) Collect key temperature data: inlet water temperature Tin, outlet water temperature Tout, and average temperatures of each zone in the tank: inlet zone T1, middle zone T2, and outlet zone T3. 2) Auxiliary data: real-time output flow rate V of the water pump and pressure P inside the tank; 3) When a single temperature fluctuation is greater than 5℃, it is considered abnormal. The average value of the previous 3 fluctuations is used to eliminate abnormal values. The data is converted into a 4~20mA analog signal and transmitted to an external controller.

[0034] The trigger conditions for each operating mode include: Heating mode: Heating is activated when the average temperature T in each zone of the tank is (T1+T2+T3) / 3 < the minimum phase change temperature of the PCM -5℃, or when a user's heating command is received. Heat release mode: Heat release is activated when the average temperature T in each zone of the tank is greater than the highest phase change temperature of the PCM by 5°C, or when a user heat release demand signal is received. Insulation mode: Insulation is activated when the PCM minimum phase change temperature -5℃ < the average temperature T in each zone of the tank < the PCM maximum phase change temperature -5℃, or when a user insulation command is received. Initial parameter settings: Heat charging mode: The initial water flow velocity is set based on the optimal flow field of the water distribution system to avoid excessive flow velocity leading to a surge in resistance. The target temperature T_target is set as the maximum phase change temperature of the PCM plus 2℃. Heat release mode: Adjust the initial water flow rate and target outlet water temperature T_out according to actual needs; Insulation mode: The water pump stops, but sensor data acquisition continues.

[0035] In step 3, coordinated control is performed under the heat charging mode. Specific operations include: 1) Based on zoned temperature-controlled flow rate regulation, the controller compares the temperatures T1, T2, and T3 in each zone of the tank with the target temperature Ttarget in real time. If T1 < T target - 3℃, meaning the inlet zone has not reached the target: maintain V = 0.8 m / s to ensure that the high-temperature water flow preferentially heats the high phase change temperature PCM in the inlet zone; If T1 ≥ T target -3℃ and T2 < T target -3℃, meaning the inlet zone meets the standard but the middle zone does not: reduce the flow rate to V = 0.6 m / s, prolong the residence time of the water in the middle zone, and allow the phase change temperature (PCM) in the middle zone to fully absorb heat; If T2 ≥ T target -3℃ and T3 < T target -3℃, meaning the middle zone meets the standard but the outlet zone does not: further reduce the flow rate to V = 0.4 m / s and focus on heating the low phase change temperature (PCM) of the outlet zone.

[0036] 2) Heating stop judgment: When T1, T2, and T3 are all ≥ T target and there is no decrease for 5 minutes, it is determined that the PCM is completely melted and the latent heat storage is saturated. The controller commands the water pump to stop and switch to heat preservation mode.

[0037] The specific operations for achieving coordinated control in exothermic mode include: Basic variable flow control, also known as anti-heat control, uses the outlet water temperature T_out as the core feedback signal and sets an adjustment threshold. If T_out ≥ T_out target + 2℃, it indicates excessive heat release. The flow rate is increased to V = 0.6 m / s to accelerate the water flow and remove heat, thus preventing the outlet water temperature from being too high. If T_out ≤ T_out target - 2℃ (e.g., 48℃): it indicates insufficient heat release. Reduce the flow rate to V = 0.4 m / s to prolong the heat exchange time between the water flow and the PCM, and utilize the EG thermal conduction network to release deep latent heat. If T_out is within the range of T_out target -2℃ to T_out target +2℃: maintain the current flow rate to ensure stable water temperature.

[0038] The PID closed loop is: By inputting the difference between the outlet temperature and the fifth preset temperature, and the water flow rate, and then supplementing the quantitative value based on conventional thermal storage system debugging experience, the pump speed is finely adjusted through PID calculation output.

[0039] The PID closed-loop is specifically as follows: When it is necessary to maintain a constant output power, a PID algorithm is introduced, specifically: Input quantities: the deviation ΔT between T_out and T_out target, i.e., T_out - T_out target, and water flow velocity V; PID parameters: Based on experience in debugging conventional thermal storage systems, the quantization values ​​are supplemented as Kp=2.5, Ki=0.5, Kd=0.1; The proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd are relatively universal and effective initial parameter settings, but they are not immutable universal values. In practical applications, they still need to be fine-tuned according to the specific system conditions. Kp=2.5 (Medium intensity): The system responds relatively sensitively to temperature deviations and can adjust quickly. Ki=0.5 (Medium intensity): The system has a certain ability to eliminate steady-state error and can eventually reach the set temperature. Kd=0.1 (Weak intensity): The system has a certain degree of predictability and is mainly used to suppress possible slight oscillations, making the temperature control process more stable.

[0040] Output: The controller fine-tunes the water pump speed based on the PID calculation results. For example, when ΔT=-3℃ and Tout=47℃, it outputs a flow rate reduction command with an adjustment step of 0.1m / s each time to avoid sudden changes in flow rate that could cause water temperature fluctuations.

[0041] Higher-order state predictive control: Input data: historical data for 5 days (T in, T out, V, T1-T3), and real-time monitoring data for 30 minutes; Predictive Model: A lumped parameter model is used to predict the solidification state of PCM in the tank within the next 15 minutes; Adjust in advance: If the predicted temperature at T is below 48℃, reduce the flow rate from 0.5m / s to 0.45m / s 5 minutes in advance to avoid a sudden drop in water temperature caused by passive adjustment.

[0042] The control method handles fault conditions in the following manner: If the third temperature sensor 403 fails, the controller will automatically replace the data at that point with the average value of other third temperature sensors 403 in the same area to ensure that the control is not interrupted. If the second temperature sensor 402 fails, the controller will temporarily use the temperature in the low phase change temperature zone to replace the outlet temperature and trigger an alarm signal at the same time. If the first temperature sensor 401 fails, the controller will temporarily replace the inlet temperature with the temperature of the high phase change temperature zone and trigger an alarm signal at the same time. Handling temperature sensor malfunctions: If the data from a single temperature sensor in the tank, such as a point in zone T1, is abnormal, such as no change for 1 minute or fluctuation >10°C, the controller will automatically replace the data at that point with the average value of the other two sensors in the same zone to ensure uninterrupted control. If the outlet sensor malfunctions, the temperature inside the tank (T3) will be used temporarily to replace the outlet temperature, and an alarm signal (audio and visual alarm) will be triggered simultaneously.

[0043] If the pressure sensor 9 detects that the pressure is lower than the first preset pressure value, the water pump will maintain a normal flow rate; If the pressure sensor 9 detects that the pressure is at the first preset pressure value and the second preset pressure value, the controller controls the water pump to reduce the flow rate and reduce the pressure rise caused by water flow impact. If the pressure sensor 9 detects that the pressure is greater than the second preset pressure value, the spring-loaded pressure relief valve 8 will open to release pressure, and at the same time the controller will control the water pump to stop working, stop releasing or charging heat, and trigger an emergency alarm.

[0044] If the pressure sensor detects P > 0.8 MPa, which is 80% of the tank's pressure threshold, the controller first reduces the flow rate, such as from 0.5 m / s to 0.3 m / s, to reduce the pressure rise caused by water flow impact. If P > 1.0 MPa, which is the pressure relief valve opening pressure, the pressure relief valve automatically opens to release pressure. At the same time, the controller cuts off the power to the water pump, stops heat release or heat charging, and triggers an emergency alarm.

[0045] In the heat-conducting module 2, the PCM phase change material expands due to heat, causing the pressure inside the tank to exceed the opening pressure of the pressure relief valve, which is then released through the spring-loaded pressure relief valve 8. The pressure sensor 9 is used to monitor the pressure in real time. When the pressure rises abnormally, the controller is triggered to cut off the heat source and sound an alarm to prevent the tank from cracking.

[0046] like Figure 5 As shown, the collaborative control of the tank's operating mode is divided into a cyclical process of data acquisition, mode determination, dynamic control, state prediction, fault monitoring, and closed-loop adjustment. The specific process includes: 1) System startup and data acquisition: After the system is powered on, the sensors of the sensing layer collect T-in, T-out, T1~T3, V, and P data at a frequency of 10 seconds / time and transmit them to the controller of the control layer in the form of analog signals. The controller preprocesses the data through the data preprocessing module, including outlier removal, such as replacing fluctuations exceeding the threshold with the mean value, and converting the analog signal into a digital signal to obtain the processed data.

[0047] 2) Mode determination: The controller compares the T-level temperature with the PCM phase change temperature range through the core control logic module to determine the operating mode of heat charging / heat dissipation / heat preservation, and sets the initial flow rate parameters; the core control logic module controls the variable flow control submodule and the flow-temperature coordinated control submodule respectively, where the variable flow control submodule plays the role of anti-heat control, and the flow-temperature coordinated control submodule plays the role of closed-loop control using PID and other algorithms for optimization.

[0048] The optional MPC model predictive control module can combine historical operating data to predict the solidification state of PCM, thereby correcting the V-shape in advance and optimizing the effect.

[0049] The controller outputs commands, i.e., digital signals, to the actuator pump in the execution layer, and the actual water flow rate is achieved by adjusting the pump speed.

[0050] 3) Corresponding mode control: Heating mode: Adjust the flow rate according to the temperature gradient of each zone until each zone reaches the target temperature, then switch to heat preservation mode; Heat release mode: First, perform variable flow control and then optimize through PID closed loop. In high-order scenarios, enable MPC prediction and make adjustments in advance. Heat preservation mode: Shutdown monitoring, waiting for the next mode trigger; 4) Real-time fault monitoring: The fault judgment module synchronously monitors the validity of sensor data and tank pressure throughout the process. If an abnormality occurs, emergency fault handling is immediately performed, including outputting an alarm signal and adjusting the flow rate if the temperature exceeds the range. 5) Closed-loop adjustment: During the control process, the actual output T and V are compared with the target values ​​every minute. If the deviation is >3%, the PID parameters or flow rate adjustment step size are re-optimized to ensure control accuracy. 6) Control termination: When the user stops demanding heat or the latent heat of the PCM is released and the temperature T < 45℃, the controller commands the system to stop, saves the data of this operation, and uses it for MPC model iteration.

[0051] This modular thermal storage tank based on high thermal conductivity composite phase change material and its collaborative control method effectively reduce the thermal resistance of the solidified layer by forming an efficient thermally conductive network through an expanded graphite skeleton, allowing latent heat to be released rapidly and achieving high thermal conductivity of the PCM. At the same time, the regular arrangement of PCM modules combined with an efficient water distribution system ensures the uniformity of water flow and heat exchange, avoids the existence of heat exchange dead zones, and effectively improves the utilization rate of PCM. The phase separation, overcooling and leakage problems of PCM are effectively solved by shaping composite and metal encapsulation. Its modular structure facilitates production, transportation and installation and maintenance, and allows for quick and easy replacement of individual modules when damaged. Meanwhile, the intelligent variable flow control strategy can adaptively adjust the operating status, effectively flatten the heat release power curve and extend the high-temperature heat release time.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A modular thermal storage tank based on a high thermal conductivity composite phase change material, characterized in that: The system includes a tank shell (1), a heat conduction module (2), a water distribution assembly (3), a monitoring module (4), a spring-loaded pressure relief valve (8), and a pressure sensor (9). The tank shell (1) is horizontally placed in the axial direction and has an internal cavity. A water distribution assembly (3) is installed at each end of the cavity. The space enclosed by the water distribution assemblies (3) at both ends and the inner wall of the tank shell (1) serves as the heat conduction module area. Multiple heat conduction modules (2) are arranged at intervals along the axial direction in the heat conduction module area. Multiple monitoring modules (4) are installed on the inner wall of the tank shell (1). A spring-loaded pressure relief valve (8) and a pressure sensor (9) are installed on the outer wall of the tank shell (1). One end of the tank shell (1) is connected to a water pump through a water pipe, and the other end is connected to a heat exchanger through a water pipe.

2. A modular thermal storage tank based on a high thermal conductivity composite phase change material according to claim 1, characterized in that: Each heat-conducting module (2) includes an aluminum encapsulation shell (201), a heat dissipation fin assembly (202), and a porous skeleton matrix (203); the aluminum encapsulation shell (201) is a plate-like structure with an inner cavity, and the porous skeleton matrix (203) is arranged in the inner cavity. The aluminum encapsulation shell (201) has through-hole arrays on both ends. Each end face of the aluminum encapsulation shell (201) has a through-hole array consisting of multiple rows of through-holes. The heat dissipation fin assembly (202) 202) includes multiple rows of heat dissipation fin arrays composed of heat dissipation fins, the through-hole array and the heat dissipation fin array are alternately arranged along the same direction on each end face of the aluminum encapsulation shell (201), and each heat dissipation fin is inclined relative to the radial plane of the aluminum encapsulation shell (201) to extend the water flow path; the porous skeleton matrix (203) is a composite structure of expanded graphite and PCM phase change material, and the PCM phase change material is one of inorganic hydrated salt, organic paraffin or fatty acid.

3. A modular thermal storage tank based on a high thermal conductivity composite phase change material according to claim 2, characterized in that: Both ends of each heat-conducting module (2) are fixedly connected to the corresponding inner sidewall of the tank shell (1) by a metal bracket (6). The gap between each two adjacent heat-conducting modules (2) is divided into three partition channels (5) by three metal plates evenly distributed in the circumference, so that the water flows axially in the partition channels (5). The partition channels (5) are used to separate the water flowing through the inside of the heat storage tank.

4. A modular thermal storage tank based on a high thermal conductivity composite phase change material according to claim 3, characterized in that: The water distribution assembly (3) includes a first porous circular plate (301) installed near one end of the tank shell (1) and a second porous circular plate (302) installed near the other end of the tank shell (1). The first porous circular plate (301) and the second porous circular plate (302) each have multiple axially through diversion channels. A water pump is connected to one end of the tank shell (1) where the first porous circular plate (301) is installed, and a heat exchanger is connected to one end of the tank shell (1) where the second porous circular plate (302) is installed.

5. A modular thermal storage tank based on a high thermal conductivity composite phase change material according to claim 4, characterized in that: The water flow direction inside the outer shell (1) of the tank is from one end where the first porous circular plate (301) is installed to the other end where the second porous circular plate (302) is installed. The arrangement of the heat-conducting modules (2) in the heat-conducting module area is arranged in order of decreasing phase change temperature of the PCM phase change material in the heat-conducting module (2) from the water flow direction, thereby forming a high phase change temperature zone near the water inlet, a medium phase change temperature zone in the middle, and a low phase change temperature zone near the water outlet.

6. A modular thermal storage tank based on a high thermal conductivity composite phase change material according to claim 5, characterized in that: The monitoring module (4) is divided into a first temperature sensor (401), a second temperature sensor (402), and a third temperature sensor (403). The first temperature sensor (401) is installed on the inner wall of the inlet end of the tank shell (1) to collect the temperature of the water flow at the inlet end as the inlet temperature. The second temperature sensor (402) is installed on the inner wall of the outlet end to collect the temperature of the water flow at the outlet end as the outlet temperature. A third temperature sensor (403) is installed on the inner wall of the tank shell (1) in each of the partition channels (5). 03) The water flow temperature in the high phase change temperature zone, the medium phase change temperature zone and the low phase change temperature zone is collected to obtain the temperature of the high phase change temperature zone, the medium phase change temperature zone and the low phase change temperature zone. The average temperature of each zone in the tank is obtained by averaging the temperature of the high phase change temperature zone, the low phase change temperature zone and the medium phase change temperature zone. The inner wall of the tank shell (1) is covered with a rock wool insulation layer (7). On the same side of the outer wall of the tank shell (1), a spring-type pressure relief valve (8) for pressure relief and a pressure sensor (9) for sensing pressure are fixedly installed.

7. A collaborative control method for a modular thermal storage tank employing the high thermal conductivity composite phase change material as described in claim 6, characterized in that, The control method includes: It has three modes: heat charging mode, heat dissipation mode, and heat preservation mode. 1) Heat charging mode: When the average temperature of each zone in the tank is lower than the first preset temperature, the water pump is turned on, so that the water flows in the heat storage tank. When the water flows through the heat conduction module (2), the PCM phase change material in the heat conduction module (2) is heated. Based on the PCM phase change material with different phase change temperatures in the axial direction, heat is stored in layers. At the same time, the water flow rate is controlled by the water pump. 2) Heat preservation mode: After step 1) heat charging mode, when the average temperature of each zone in the tank rises to between the first preset temperature and the second preset temperature, the water pump stops, so that the water flow in the heat storage tank stops. 3) Heat release mode: When the average temperature of each zone in the tank rises to a level greater than the second preset temperature, the water pump is turned on. When the water flows through the heat conduction module (2), the PCM phase change material in the heat conduction module (2) releases heat. Based on the PCM phase change material with different phase change temperatures in the axial direction, heat is released in layers. The flow rate and temperature are coordinated by using PID closed-loop optimization to optimize the water flow rate through the water pump.

8. The collaborative control method for a modular thermal storage tank made of high thermal conductivity composite phase change material according to claim 7, characterized in that, The specific steps of step 1) heat charging mode coordinated control are as follows: Real-time comparison of temperatures in the high phase transition temperature zone, low phase transition temperature zone, and medium phase transition temperature zone with the second preset temperature: If the temperatures in the high phase change temperature zone, low phase change temperature zone, and medium phase change temperature zone are all lower than the third preset temperature, the water pump will maintain a fixed water flow rate to ensure water flow. If the temperature in the high phase change temperature zone is not less than the third preset temperature, and the temperatures in the low phase change temperature zone and the medium phase change temperature zone are all lower than the third preset temperature, the water pump will reduce the water flow rate. If the temperatures in the high phase change temperature zone and the low phase change temperature zone are not lower than the third preset temperature, and the temperature in the medium phase change temperature zone is lower than the third preset temperature, the water pump will further reduce the flow rate. If the temperatures in the high phase change temperature zone, low phase change temperature zone, and medium phase change temperature zone are all not lower than the third preset temperature and are maintained for a certain period of time, the water pump will stop and switch to the heat preservation mode.

9. The collaborative control method for a modular thermal storage tank made of high thermal conductivity composite phase change material according to claim 7, characterized in that, Step 3) of the heat release mode coordinated control specifically involves: Using the outlet temperature as the core feedback signal, the water flow rate is set via the water pump: If the outlet temperature is not lower than the fourth preset temperature, the water pump will increase the flow rate. If the outlet temperature is not greater than the fifth preset temperature, the water pump will reduce the flow rate. If the outlet temperature is between the fourth and fifth preset temperatures, the water pump will maintain the current flow rate. The PID closed-loop optimization specifically involves: By inputting the difference between the outlet temperature and the fifth preset temperature, and the water flow rate, and then supplementing the quantitative value based on conventional thermal storage system debugging experience, the pump speed is adjusted through PID calculation output results.

10. The collaborative control method for a modular thermal storage tank made of high thermal conductivity composite phase change material according to claim 7, characterized in that: The control method handles fault conditions in the following manner: If the third temperature sensor (403) fails, the average value of other third temperature sensors (403) in the same area shall be used to replace the data at that point. If the second temperature sensor (402) fails, the outlet temperature will be temporarily replaced by the temperature in the low phase change temperature zone. If the first temperature sensor (401) fails, the temperature of the high phase change temperature zone will be used temporarily to replace the inlet temperature. If the pressure sensor (9) detects that the pressure is lower than the first preset pressure value, the water pump maintains the normal flow rate; If the pressure sensor (9) detects that the pressure is at the first preset pressure value and the second preset pressure value, the water pump will reduce the flow rate; If the pressure sensor (9) detects that the pressure is greater than the second preset pressure value, the spring-loaded pressure relief valve (8) will open to release pressure, and the water pump will stop working.

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