A phase change energy storage structure for a heat exchange system and a control method

Abstract

A phase change energy storage structure for heat exchange system, comprising a fan, an evaporator, a cold box and a cold storage device, air passes through the fan, the evaporator and the cold storage device in turn when charging, and passes through the fan, the cold storage device and the cold box in turn when discharging, the cold storage device comprises a plurality of cold storage tanks, two ports of all the cold storage tanks are connected with an air inlet pipe and an air outlet pipe respectively, and air inlet valves and air outlet valves are correspondingly arranged, when the number of the cold storage tanks is greater than one, the cold storage tanks are connected in turn and connection valves are correspondingly arranged. The cold energy utilization efficiency of the cold storage device is improved by combining the cold storage tanks.

Description

Technical Field

[0001] This invention belongs to the field of heat exchange, and particularly relates to a phase change energy storage structure and control method for heat exchange systems. Background Technology

[0002] In recent years, compressed air energy storage systems have been commercially constructed and operated in many parts of my country. For example, the insulated compressed air energy storage system successfully connected to the grid in Feicheng, Shandong in September 2021 has an installed capacity of 10MW. However, due to its large volume, high-pressure air, as the energy storage medium, requires large-capacity mines and salt caverns for storage, which limits the large-scale application of the system. To address this, liquid air energy storage technology has been proposed, which uses a cold storage unit to throttle high-pressure air into atmospheric pressure low-temperature liquid air. This not only truly realizes convenient storage of the working medium but also improves the economic efficiency of system operation through the recovery and utilization of cold energy.

[0003] Currently, both Mitsubishi Electric of Japan and Highview of the UK are actively researching liquid air energy storage technology. Highview, in collaboration with the University of Leeds, built the world's first 350kW / 2.5MWh liquid air energy storage demonstration project and is also constructing a 50MW / 250MWh energy storage power station in Manchester. In contrast, my country's liquid air energy storage technology development started later; the first 500kW liquid air energy storage demonstration project was only established in Tongli, Suzhou in 2018. Overall, although the construction technology of liquid air compressed energy storage power stations is becoming increasingly mature, it faces the same challenges as most energy storage systems when expanding on a large scale, such as grid coordination and control, and the compatibility of power machinery with frequency conversion efficiency enhancements.

[0004] To achieve a smooth transition from kilowatt to megawatt-level liquid air energy storage systems, it's not a matter of simply expanding existing facilities. The increase in cold energy storage capacity will inevitably exacerbate the conflict between operating costs and charging / discharging efficiency. Therefore, the development level of efficient cold storage and heat release devices will determine the compressed air liquefaction rate and the system's cycle power generation, thus serving as a key core technology for large-scale engineering applications. How to achieve comprehensive improvements and breakthroughs in existing technologies while balancing system stability and economic efficiency is of great practical significance for promoting the industrial upgrading of megawatt-level liquid air energy storage systems.

[0005] The operating characteristics of liquid air energy storage systems place higher demands on the overall capacity and quality of heat and cold storage / release. In recent years, domestic and international developers have conducted research on the selection of energy storage materials, overall device design, and optimization of operating conditions. Researchers generally use solid-phase materials, such as stone, and liquid-phase materials, such as organic working fluids. Solid-phase cold storage technology is simple and mature; the Institute of Industrial Thermal Engineering, Chinese Academy of Sciences, has found that rock has strong resistance to thermal fatigue, and systems made from it have a long service life. However, its relatively low storage density and cycle efficiency need further improvement. Researchers at Ruhr University in Germany have pointed out that even when using high thermal conductivity metals as filling media, the system's heat storage and release efficiency is still unsatisfactory. The most common liquid-phase cold storage media are methanol and propane. A study by the Institute of Physics and Chemistry, Chinese Academy of Sciences, shows that a mixture of these two can achieve a cold storage efficiency of over 90% while avoiding the axial thermal conduction effect of solid-phase media. However, organic working fluids are usually flammable, posing significant safety hazards in engineering applications. Currently, phase change energy storage materials also suffer from problems such as poor matching of operating temperature ranges and high cost. If they are to be applied on a large scale to liquid air energy storage systems, these technical bottlenecks must be given sufficient attention.

[0006] As a typical energy storage unit, a packed bed can be considered a direct-contact heat exchanger. The flow and heat transfer characteristics of the regenerating and cooling medium within it have a significant impact on the device's efficiency and operating energy consumption. North China Electric Power University proposed that increasing the height of the packed bed and reducing the diameter of the filling solid particles helps improve the effective capacity ratio of the cold storage system. Shanghai Jiao Tong University has also conducted optimization analyses on the optimal packaging shape and stacking method of the cold storage unit. Regarding operating parameters, the Institute of Physics and Chemistry of the Chinese Academy of Sciences believes that the flow rate of the heat exchange medium is highly correlated with the energy loss of the packed bed. The University of Tehran in Iran points out that changes in the pressure of the cold storage medium are also a major parameter affecting the macroscopic operating condition of the cold storage unit. The Global Energy Interconnection Research Institute has found that a reasonable setting of the cutoff temperature can effectively improve the effective volume ratio. Considering the difficulty of accurately depicting the internal composition and temperature field of the bed, most related studies use numerical simulation methods. However, for irregular rock-filled beds, ordinary porous media models or jet models often cause significant calculation errors. In addition, the China Shipbuilding Technology Research Institute focused on insulation technology in the field of liquid air, compared and analyzed the implementation effects and limitations of various existing technologies such as vacuum insulation, powder filling, and laminated insulation, and pointed out the necessity of developing a new generation of low-cost, high-performance insulation materials such as polyethylene foam.

[0007] Existing liquid air energy storage technologies, particularly those using solid-state thermal storage devices, suffer from several drawbacks. Firstly, while these devices utilize solid-state thermal storage, their low energy density leads to reduced cold storage capacity. Secondly, most devices involve direct stacking of solid-state cold storage media, resulting in excessive flow resistance. Thirdly, the stone used in cold storage devices also suffers from low energy density and excessively large thermoclines, impacting system efficiency. Finally, the actual required cold storage capacity exceeds the available capacity, meaning current cold storage levels cannot meet production demands. Summary of the Invention

[0008] The purpose of this invention is to provide a phase change energy storage structure and control method for heat exchange systems, so as to solve the technical problem of how to improve the utilization efficiency of cold storage devices by combining cold storage tanks.

[0009] To achieve the above objectives, the specific technical solution of the phase change energy storage structure and control method for a heat exchange system according to the present invention is as follows:

[0010] A phase change energy storage structure for a heat exchange system includes a fan, an evaporator, a cold box, and a cold storage device. During cooling, air passes sequentially through the fan, evaporator, and cold storage device; during cooling release, air passes sequentially through the fan, cold storage device, and cold box. The cold storage device comprises several cold storage tanks, each with two ports connected to an inlet pipe and an outlet pipe, respectively, and corresponding inlet and outlet valves are provided. When the number of cold storage tanks is greater than one, adjacent cold storage tanks are connected sequentially, with corresponding connection valves provided.

[0011] In order to improve the cold energy utilization efficiency at both ends of the cold storage tank, and at the same time, the filling of foam metal can effectively prevent the cold air in the cold storage tank from suddenly entering the cold storage tank under extremely cold conditions and damaging the phase change cold storage ball, a guide plate, foam metal and fixed bed are arranged between the two ports of the cold storage tank from the outside to the inside.

[0012] In order to improve the cold energy utilization rate of the thermocline and reduce the thickness of the thermocline in this area, the foam metal is set according to the thickness of the thermocline where the heat transfer fluid flows in and out of the guide plate, and the porosity is 0.3 to 0.6.

[0013] In order to better enhance the gas turbulence inside the device and improve the heat exchange efficiency, the staggered arrangement of phase change cold storage balls with hierarchical ordered pores can effectively regulate the gas flow channel entering the cold storage device and reduce the flow resistance of the device. The fixed bed is filled with phase change cold storage balls with gradually increasing diameter from the outside to the inside.

[0014] In order to make full use of the cold energy of liquid air and improve the cold storage efficiency, the problem of excessive irreversible heat loss of solid energy storage medium is solved by using phase change cold storage material. The outer shell of the phase change cold storage ball is metal and the inside is filled with phase change energy storage material.

[0015] In order to improve heat exchange efficiency and reduce the thickness of the sloping temperature layer, the phase change cold storage ball is filled with phase change energy storage materials with different phase change temperatures, ranging from -150℃ to 20℃, and arranged in descending order of phase change temperature in the direction of cold air release.

[0016] In order to increase the contact area between the gas and the phase change cold storage ball and reduce the flow dead zone, the phase change cold storage ball is a sphere that gradually shrinks from the middle to both ends, with the two ends placed in the direction of gas flow.

[0017] To enhance heat exchange efficiency, the surface of the phase change cold storage ball is coated with a high thermal conductivity coating.

[0018] To further increase the contact area between the gas and the phase change cold storage ball, the surface of the phase change cold storage ball has protrusions to increase the contact area with the passing gas.

[0019] In order to better utilize and recover the energy generated by the split hot and cold air medium after passing through the energy storage medium, the guide plate is grid-shaped.

[0020] In order to achieve the function of controlling the valve by setting a preset temperature, the cold storage tank is equipped with temperature monitoring modules at both ports and inside.

[0021] A control method for a phase change energy storage structure for a heat exchange system includes a cooling charge process and a cooling release process.

[0022] The valve through which gas enters the cold storage tank is called the inlet valve, and the valve through which gas exits the cold storage tank is called the outlet valve. The valve between the two cold storage tanks is called the connecting valve.

[0023] The cold storage tanks are divided into several cold storage groups, and each cold storage group includes several cold storage tanks.

[0024] The first cold storage tank in each group is designated as the first cold storage tank, with its inlet valve designated as the first inlet valve and its outlet valve designated as the first outlet valve. The next tank connected in sequence is the second cold storage tank, and so on. The last cold storage tank in each group is designated as the last cold storage tank.

[0025] The cooling process includes the following steps:

[0026] S1.1 The fan discharges air into the evaporator.

[0027] S1.2. After the air is cooled by the evaporator, the cold energy is carried into the cold storage device.

[0028] S1.3 With all valves in the cold storage device closed, open the inlet and outlet valves of the first cold storage tank in each cold storage group to charge the first cold storage tank of each cold storage group.

[0029] S1.4 When the outlet temperature of the first cold storage tank reaches the preset charging temperature, close the first air outlet valve and open the connecting valve and the second air outlet valve between the first and second cold storage tanks to form a series charging of the first and second cold storage tanks.

[0030] S1.5 When the internal temperature of the first cold storage tank reaches the preset charging temperature, the charging of the first cold storage tank is completed. Close the first air inlet valve and the connecting valve between the first cold storage tank and the second cold storage tank, and open the second air inlet valve to form a single tank charging of the second cold storage tank.

[0031] S1.6 When the outlet temperature of the second cold storage tank reaches the preset charging temperature, close the second air outlet valve and open the connecting valve between the second and third cold storage tanks and the third air outlet valve to form a series charging of the second and third cold storage tanks.

[0032] S1.7. Continue this process until the last cold storage tank of each cold storage group is fully charged, at which point the charging process ends.

[0033] The cold release process takes the last cold storage tank in each cold storage group to complete the cold charging process as the first cold storage tank, and the cold release process includes the following steps:

[0034] S2.1 The fan discharges air into the cold storage device;

[0035] S2.2 With all valves in the cold storage device closed, open the inlet and outlet valves of the first cold storage tank in each cold storage group to release cold from the first cold storage tank;

[0036] S2.3 When the outlet temperature of the first cold storage tank reaches the preset cold release temperature, close the first vent valve and open the connecting valve and the second vent valve between the first and second cold storage tanks to form a series cold release between the first and second cold storage tanks.

[0037] S2.4 When the internal temperature of the first cold storage tank reaches the preset cold release temperature, the cold release of the first cold storage tank is completed. Close the first air inlet valve and the connecting valve between the first cold storage tank and the second cold storage tank, and open the second air inlet valve to form a single-tank cold release of the second cold storage tank.

[0038] S2.5 When the outlet temperature of the second cold storage tank reaches the preset cold release temperature, close the second vent valve and open the connecting valve between the second and third cold storage tanks and the third vent valve to form a series cold release between the second and third cold storage tanks.

[0039] S2.6. Continue this process until the last cold storage tank of each cold storage group has finished releasing cold energy, and the released cold energy enters the cold box, thus ending the cold release process. Beneficial effects

[0040] The inlet and outlet of the cold storage device are filled with foamed metal with a porosity of 0.3 to 0.6 according to the thickness of the thermocline, which improves the utilization rate of the thermocline's cold energy. The cold storage medium inside the device is a phase change energy storage material, and the phase change temperature of the medium is distributed according to the temperature gradient of the gas inside the device. The cold storage medium inside the device is macro-encapsulated in the form of spheres, and the phase change spheres form a stepped flow channel with gradually increasing diameter along the gas flow direction to improve the heat exchange efficiency with the fluid. The system adopts a multi-tank series combination, and the charging and releasing process uses a fan as the main driving force. The charging and releasing stages are achieved by switching valves on the main pipeline and branch pipelines. The structure is simple and greatly expands the cold storage capacity of the cold storage device, maximizing the energy storage density and cold / heat storage / release cycle efficiency of the device. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a phase change energy storage structure for a heat exchange system according to the present invention.

[0042] Figure 2 This is a schematic diagram of the cold storage tank structure of the present invention;

[0043] Figure 3 This is a schematic diagram of the arrangement of phase change cold storage spheres that gradually decrease in size from the middle to both ends;

[0044] Figure 4 A schematic diagram of gas passing through a spherical phase change cold storage sphere;

[0045] Figure 5 A schematic diagram of gas passing through a phase change cold storage sphere that gradually narrows from the middle to both ends;

[0046] Figure 6 This is a schematic diagram of the cold storage tank connection in Example 1;

[0047] Figure 7 This is a schematic diagram of the cold storage tank connection in Example 2;

[0048] Explanation of markings in the diagram: 1000, Fan; 2000, Evaporator; 3000, Cold Box; 4000, Cold Storage Device; 5000, Cold Charging Direction; 6000, Cold Release Direction; 4100, Cold Storage Tank; 4110, Port; 4120, Baffle Plate; 4130, Foam Metal; 4140, Fixed Bed; 4150, Phase Change Cold Storage Ball; 4151, Shell; 4152, Phase Change Energy Storage Material; 4201, Inlet Valve; 4202, Outlet Valve; 4203, Connecting Valve; 4301, Inlet Pipe; 4302, Outlet Pipe. Detailed Implementation

[0049] To better understand the purpose, structure, and function of this invention, the following detailed description, in conjunction with the accompanying drawings, provides an explanation of a phase change energy storage structure and control method for a heat exchange system. Example

[0050] like Figure 1 As shown, a phase change energy storage structure for a heat exchange system includes a fan 1000, an evaporator 2000, a cold box 3000, a cold storage tank 4100, and valves. During the energy storage process of the liquid air energy storage system, this system performs a cold release process. The fan 1000 uses ambient temperature air as a heat transfer medium, passing it through the cold storage tank 4100 and extracting high-quality cold energy, which is then input into the cold box as an external cold source. During the energy release process of the liquid air energy storage system, this system performs a cold storage process. The fan 1000 drives ambient temperature air to flow through the evaporator 2000, recovering the evaporative cold energy of the liquid air and storing it in the cold storage tank 4100. Inside the cold storage tank 4100, the hot and cold air medium is diverted by a guide plate 4120, transferring the cold energy to the energy storage medium.

[0051] like Figure 2 As shown, the cold storage tank 4100 has a guide plate 4120, a foam metal 4130 and a fixed bed 4140 arranged sequentially from the outside to the inside along the inner axis of the two ports 4110.

[0052] After the guide plate 4120, the inlet and outlet are filled with foam metal 4130 with stronger heat transfer performance according to the thickness of the inclined temperature layer of the heat transfer fluid flow. The foam metal 4130 is mostly made of foam copper or foam aluminum. The porosity of the foam metal 4130 skeleton is 0.3 to 0.6 to improve the cold energy utilization rate of the inclined temperature layer and reduce the thickness of the inclined temperature layer in this area. The filling of foam metal 4130 can effectively prevent the phase change sphere from being damaged by the sudden entry of cold air into the cold storage device under extremely cold conditions.

[0053] The fixed bed 4140 between the two layers of foamed metal 4130 is divided into stepped operating temperature zones, and phase change energy storage balls 4150 with corresponding operating temperatures are configured. The metal outer shell 4151 of the phase change energy storage ball 4150 is made of stainless steel, and the ball is filled with phase change energy storage material 4152. The operating temperature of the phase change energy storage material is -150 to 20℃, including diethylene glycol, n-valeric acid, butyl methyl ether, n-pentane, and chlorotrifluoromethane. The use of phase change energy storage material 4152 can greatly reduce the problem of excessive irreversible heat transfer loss of solid energy storage media, make full use of liquid air cold energy, and improve cold storage efficiency.

[0054] The phase change energy storage spheres 4150 are arranged in a staggered pattern with increasing diameter along the gas flow direction, using an ordered pore arrangement to create better regional airflow, thereby improving heat exchange efficiency and reducing the thickness of the thermocline. This concept of energy cascading utilization greatly meets the requirements for efficient storage of cold energy of different qualities over a wide temperature range, truly achieving an integrated design of the cold storage device.

[0055] When the cold storage tank 4100 is charged, ultra-low temperature air is introduced from the bottom of the fixed bed 4140, flows through multiple temperature-controlled filling areas, and transfers the cold energy of different grades to the mixed cold storage medium in stages before flowing out from the top. The phase change energy storage material 4152 undergoes a solidification process while maintaining a constant temperature, thereby reducing the thickness of the twill layer. When the cold storage tank 4100 is discharged, room temperature air flows in from the top of the cold storage tank 4100, absorbs the cold energy of the layered areas within the fixed bed 4140 in stages, and flows out from the bottom. At this time, the phase change material undergoes a melting process while maintaining a constant temperature, which also reduces the thickness of the twill layer. In addition, in order to reduce flow resistance and improve the cold storage efficiency of the device during the implementation of this embodiment, each single tank will be designed in series and parallel combination according to the requirements of different cold storage durations, thereby forming a multi-stage cold storage linkage unit, thereby maximizing the energy storage density and cold and heat storage and release cycle efficiency of the device while improving the system compactness. The cold air first passes through the more resilient foam metal 4130, and then through phase change cold storage balls 4150 of different diameters to recover and utilize the cold energy of the liquid air, which can effectively improve the cold storage efficiency and greatly improve the liquid air energy storage efficiency.

[0056] like Figure 3 As shown, the phase change cold storage spheres 4150 have a shape that gradually tapers from the middle to both ends, and their arrangement in the cold storage tank 4100 is as follows. Figure 3 As shown. Figure 4-5 As shown, compared to the spherical phase change cold storage ball 4150, the phase change cold storage ball 4150, which gradually shrinks from the middle to both ends, has a larger contact area with the gas and a smaller flow dead zone, resulting in better heat exchange efficiency.

[0057] Applying a high thermal conductivity coating to the surface of the phase change cold storage ball 4150 and creating irregular grooves on the surface of the phase change cold storage ball 4150 can increase the contact area with the gas and further improve the heat exchange efficiency.

[0058] like Figure 6 As shown, for the multi-tank combined cold storage device 4000, this embodiment adopts a multi-tank combined design concept, with the phase change cold storage ball being spherical, thereby realizing the control of the tank charging and releasing time. In order to reduce the pressure of the air intake cold storage device, each tank is equipped with an independent control valve according to the cold storage / releasing time requirements. When it is necessary to extend the cold storage time, the control valves of multiple cold storage tanks can be opened to realize parallel charging of the tanks, reducing the system charging power consumption. The charging state is determined and evaluated by testing multiple temperature measuring points arranged along the axial direction of the tank, and this evaluation serves as the basis for determining the charging and releasing cutoff point.

[0059] In use, this embodiment takes a combination of four cold storage tanks 4100 as an example. The gas entry order from left to right is the first cold storage tank, the second cold storage tank, the third cold storage tank, and the fourth cold storage tank. The first and second cold storage tanks are the first cold storage group, and the third and fourth cold storage tanks are the second cold storage group.

[0060] The cooling process begins with fan 1000 discharging air into the evaporator. After passing through evaporator 2000, the air carries the cold energy into the cold storage device 4000. All valves in the cold storage device 4000 are closed. The inlet valves 4201 and outlet valves 4202 of the first and third cold storage tanks are opened to charge them. When the outlet temperatures of the first and third cold storage tanks reach the preset charging temperature, the first and third outlet valves 4202 are closed. The connecting valve between the first and second cold storage tanks and the second outlet valve 4202 are opened. The connecting valve 4203 between the third and fourth cold storage tanks and the fourth outlet valve are also opened, forming a series charging of the first and second cold storage tanks, and the series charging of the third and fourth cold storage tanks. When the internal temperature of the first cold storage tank reaches the preset charging temperature... When the internal temperature of the first cold storage tank reaches the preset charging temperature, the charging of the first cold storage tank is completed. The first air inlet valve 4201 and the connecting valve 4203 between the first and second cold storage tanks are closed, and the second air inlet valve 4201 is opened to form single-tank charging of the second cold storage tank. When the internal temperature of the third cold storage tank reaches the preset charging temperature, the charging of the third cold storage tank is completed. The third air inlet valve 4201 and the connecting valve 4203 between the third and fourth cold storage tanks are closed, and the fourth air inlet valve 4201 is opened to form single-tank charging of the fourth cold storage tank. When the outlet temperature of the second and fourth cold storage tanks reaches the preset charging temperature, the second and fourth air outlet valves 4202 are closed. At this time, the charging of the second and fourth cold storage tanks is completed, that is, the charging of the first and second cold storage groups is completed, and the charging process ends.

[0061] The cooling process uses the tank that is at the end of the cooling process as the first cold storage tank. The fan 1000 discharges air into the cold storage device 4000 in the reverse direction of the cooling process. The cooling process of the tank is determined by the cooling preset temperature of the tank temperature module. The cooling process is completed in the reverse direction of the cooling process, and the released cold energy enters the cold box 3000. Example

[0062] When a shorter cooling time is required, the cooling system will be operated using a single-tank series cooling system, such as... Figure 7 As shown, this embodiment takes three cold storage tanks connected in series as an example. The phase change cold storage ball is spherical, and the gas entry order from left to right is the first cold storage tank, the second cold storage tank, and the third cold storage tank.

[0063] All valves in the cold storage device 4000 are closed. The inlet valve 4201 and outlet valve 4202 of the first cold storage tank are opened to charge the first cold storage tank. When the outlet temperature of the first cold storage tank reaches the preset charging temperature, the first outlet valve 4202 is closed, and the connecting valve 4203 and the second outlet valve 4202 between the first and second cold storage tanks are opened, forming a series charging connection between the first and second cold storage tanks. When the internal temperature of the first cold storage tank reaches the preset charging temperature, the charging of the first cold storage tank is complete. The first inlet valve 4201 and the connecting valve 4203 between the first and second cold storage tanks are closed, and the second inlet valve 4201 is opened, forming a series charging connection between the second cold storage tank. Single-tank cooling: When the outlet temperature of the second cold storage tank reaches the preset cooling temperature, the second outlet valve 4202 is closed, and the connecting valve 4203 between the second and third cold storage tanks and the third outlet valve 4202 are opened, forming a series cooling process between the second and third cold storage tanks; when the internal temperature of the second cold storage tank reaches the preset cooling temperature, the cooling process of the second cold storage tank is complete, the second inlet valve 4201 is closed, and the connecting valve 4203 between the second and third cold storage tanks is opened, forming a single-tank cooling process for the third cold storage tank; when the internal temperature of the third cold storage tank reaches the preset cooling temperature, the cooling process of the third cold storage tank is complete, and so on until the cooling process ends.

[0064] The cooling process uses the tank that is at the end of the cooling process as the first cold storage tank. The fan 1000 discharges air into the cold storage device 4000 in the reverse direction of the cooling process. The cooling process of the tank is determined by the cooling preset temperature of the tank temperature module. The cooling process is completed in the reverse direction of the cooling process, and the released cold energy enters the cold box 3000.

[0065] Number of cold storage tanks in the cold storage group Total thickness of the thermocline (m) Pressure drop (kPa) Cold storage efficiency Cooling time (h) 1 32.2 542.94 89.68% 7.3 2 30.5 287.1 89.9% 5.2 3 29.4 185.11 90.58% 4.5 5 41.5 113.54 86.70% 3.8 7 50.4 82.87 83.84% 3.6 10 61.2 59.87 80.38% 3.1 20 83.2 34.80 73.33% 2.1

[0066] Table 1

[0067] Table 1 shows the data of the system of the present invention under different conditions of the number of cold storage tanks in each cold storage group. The values ​​are the average values ​​of multiple experimental data. The cold storage system in Example 2 is when the number of cold storage tanks in the cold storage group is 1, and the cold storage system in Example 1 is when the number of cold storage tanks in the cold storage group is 2. As shown in Table 1, when the number of cold storage tanks in each cold storage group is 3, the cold storage efficiency is relatively high.

[0068] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the guidance of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A phase change energy storage structure for a heat exchange system, comprising a fan, an evaporator, a cold box, and a cold storage device, wherein during cooling, air passes sequentially through the fan, the evaporator, and the cold storage device, and during cooling release, air passes sequentially through the fan, the cold storage device, and the cold box, characterized in that, The cold storage device includes several cold storage tanks. The two ports of all cold storage tanks are connected to the inlet pipe and the outlet pipe, respectively, and inlet valves and outlet valves are provided accordingly. When the number of cold storage tanks is greater than one, adjacent cold storage tanks are connected in sequence, and connection valves are provided accordingly. Between the two ports of the cold storage tank, a baffle plate, foamed metal, and a fixed bed are arranged sequentially from the outside to the inside. The foam metal is set according to the thickness of the inclined temperature layer for the flow of heat transfer fluid into and out of the guide plate, and has a porosity of 0.3 to 0.

6. The fixed bed is filled with phase change energy storage balls in a manner that gradually increases in diameter from the outside to the inside. The outer shell of the phase change energy storage balls is metal, and the inside is filled with phase change energy storage material. The phase change energy storage ball is filled with phase change energy storage materials with different phase change temperatures, ranging from -150℃ to 20℃, and arranged in descending order of phase change temperature in the direction of the cold air release. The phase change cold storage ball is a sphere that gradually shrinks from the middle to both ends, with the two ends positioned in the direction of gas flow.

2. The phase change energy storage structure for a heat exchange system according to claim 1, characterized in that, The surface of the phase change cold storage ball is coated with a high thermal conductivity coating to enhance heat exchange efficiency.

3. The phase change energy storage structure for a heat exchange system according to claim 1, characterized in that, The surface of the phase change cold storage ball has protrusions to increase the contact area with the passing gas.

4. The phase change energy storage structure for a heat exchange system according to claim 1, characterized in that, The guide plate is grid-shaped.

5. The phase change energy storage structure for a heat exchange system according to claim 1, characterized in that, The cold storage tank is equipped with temperature monitoring modules at both ports and inside.

6. A control method for a phase change energy storage structure for a heat exchange system as described in any one of claims 1-5, characterized in that, Including the cooling process and the cooling release process, The valve through which gas enters the cold storage tank is called the inlet valve, and the valve through which gas exits the cold storage tank is called the outlet valve. The valve between the two cold storage tanks is called the connecting valve. The cold storage tanks are divided into several cold storage groups, and each cold storage group includes several cold storage tanks. The first cold storage tank in each group is designated as the first cold storage tank, with the inlet valve of the first cold storage tank designated as the first inlet valve and the outlet valve designated as the first outlet valve. The next tank connected in sequence is the second cold storage tank, and so on. The last cold storage tank in each group is designated as the last cold storage tank. The cooling process includes the following steps: S1.1 The fan discharges air into the evaporator. S1.

2. After the air is cooled by the evaporator, the cold energy is carried into the cold storage device. S1.3 With all valves in the cold storage device closed, open the inlet and outlet valves of the first cold storage tank in each cold storage group to charge the first cold storage tank of each cold storage group. S1.4 When the outlet temperature of the first cold storage tank reaches the preset charging temperature, close the first air outlet valve and open the connecting valve and the second air outlet valve between the first and second cold storage tanks to form a series charging of the first and second cold storage tanks. S1.5 When the internal temperature of the first cold storage tank reaches the preset charging temperature, the charging of the first cold storage tank is completed. Close the first air inlet valve and the connecting valve between the first cold storage tank and the second cold storage tank, and open the second air inlet valve to form a single tank charging of the second cold storage tank. S1.6 When the outlet temperature of the second cold storage tank reaches the preset charging temperature, close the second air outlet valve and open the connecting valve between the second and third cold storage tanks and the third air outlet valve to form a series charging of the second and third cold storage tanks. S1.

7. Continue this process until the last cold storage tank of each cold storage group is fully charged, at which point the charging process ends. The cold release process takes the last cold storage tank in each cold storage group to complete the cold charging process as the first cold storage tank, and the cold release process includes the following steps: S2.1 The fan discharges air into the cold storage device; S2.2 With all valves in the cold storage device closed, open the inlet and outlet valves of the first cold storage tank in each cold storage group to release cold from the first cold storage tank; S2.3 When the outlet temperature of the first cold storage tank reaches the preset cold release temperature, close the first vent valve and open the connecting valve and the second vent valve between the first and second cold storage tanks to form a series cold release between the first and second cold storage tanks. S2.4 When the internal temperature of the first cold storage tank reaches the preset cold release temperature, the cold release of the first cold storage tank is completed. Close the first air inlet valve and the connecting valve between the first cold storage tank and the second cold storage tank, and open the second air inlet valve to form a single-tank cold release of the second cold storage tank. S2.5 When the outlet temperature of the second cold storage tank reaches the preset cold release temperature, close the second vent valve and open the connecting valve between the second and third cold storage tanks and the third vent valve to form a series cold release between the second and third cold storage tanks. S2.

6. Continue this process until the last cold storage tank of each cold storage group has finished releasing cold energy, and the released cold energy enters the cold box, thus ending the cold release process.

Images