Compact molten salt heat exchange and molten salt phase state detection device
By combining a containerized structure with ultrasonic monitoring components, the adaptability of molten salt thermal storage devices when the usage location changes is solved, achieving modular design and real-time phase monitoring, thus improving thermal storage efficiency and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG GUOHUA YUYAO FUEL GAS POWER GENERATION CO LTD
- Filing Date
- 2025-12-15
- Publication Date
- 2026-05-12
AI Technical Summary
Existing molten salt thermal energy storage devices require customized enclosures with specific power and storage capacity when the application site changes, and the monitoring of the internal melting state is ineffective, lacking modular and mass production capabilities.
The compact molten salt heat exchanger adopts a container-type structure, utilizes finned tubes and ultrasonic monitoring components for real-time phase state detection, and combines multi-cascade devices to optimize space utilization and heat storage, achieving a modular design.
It improves space utilization, ensures stable charging and discharging power, enables convenient expansion of thermal storage capacity, and can monitor the molten salt phase in real time, adapting to different usage scenarios.
Smart Images
Figure CN122015546A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of peak shaving technology for molten salt systems, specifically relating to a compact molten salt heat exchange and molten salt phase detection device. Background Technology
[0002] Current research on molten salt thermal storage devices mainly focuses on enhancing heat exchange and achieving precise control and monitoring. However, most existing technologies only consider efficiency and do not fundamentally optimize the total heat exchange. When the application environment of the device changes, it is necessary to customize a tank with specific power and storage capacity. The ideas on control and monitoring mainly rely on changes in liquid level to generate electrical signal changes, which can only reflect the overall state of the salt tank and is not effective in reflecting the melting state of individual internal locations.
[0003] An existing invention patent (CN118623679A) discloses a composite high thermal conductivity molten salt device, which relates to the field of heat transfer technology. It uses multiple molten salt heat storage material components, each with multiple heat-conducting material components arranged parallel and spaced apart along their length. The thermal conductivity of the heat-conducting material components is >50W / (m·K). A through fluid channel is opened in the heat-conducting material component along its length for introducing fluid to store or release heat on the molten salt heat storage material component.
[0004] Invention patent (CN105424740A) discloses a performance testing device for molten salt heat exchange / storage equipment, including a high-temperature molten salt circulation loop and a cascade cooling system (heat transfer oil circulation loop and cooling water circulation loop). A combination of variable frequency pumps, valves, and bypass pipelines ensures precise adjustment of the working fluid flow over a wide range. Multiple electric heaters are installed, and the heating power and temperature can be precisely adjusted over a wide range using thyristor-controlled automatic power regulation. The introduction of nitrogen gas isolates the molten salt and heat transfer oil from air, significantly extending their service life. This invention provides a comprehensive experimental platform for testing the molten salt heat exchange or storage performance, featuring multiple functions. It is suitable not only for testing the flow, heat exchange, and heat storage performance of molten salt working fluids but can also be extended to other liquid working fluids.
[0005] Most existing invention patents only consider efficiency issues and do not fundamentally optimize the total heat exchange. When the application location of the device changes, it is necessary to customize a box with specific power and storage capacity. In addition, in existing invention patents, the ideas on control and monitoring mainly rely on the change of liquid level to generate electrical signal changes. This can only reflect the overall state of the salt tank and is not effective in reflecting the melting state of each internal location.
[0006] Current research on molten salt thermal energy storage devices mainly focuses on enhancing heat exchange and achieving precise control and monitoring. Existing technologies can only provide macroscopic control and regulation, or have poor equipment adaptability, preventing modular and mass production. Summary of the Invention
[0007] This invention primarily addresses the aforementioned problems by providing a compact molten salt heat exchanger and molten salt phase detection device. It utilizes a containerized molten salt heat exchanger for space optimization and modular design, ensuring each container has consistent size and capacity, facilitating the expansion of flow channels and increasing the overall heat storage capacity of the thermal storage system. The specific technical solution of this invention is as follows:
[0008] A compact molten salt heat exchange and molten salt phase detection device includes a box-shaped device shell, the inside of which is divided into multiple chambers by a partition layer, and each chamber is filled with a phase change material with a different phase change temperature;
[0009] Each chamber is equipped with a finned tube, which includes a heat exchange medium pipe and fins located on the outside of the pipe; the finned tubes in each chamber are connected in series, and the heat exchange medium entering each chamber flows from bottom to top in the heat exchange medium pipe;
[0010] The chamber is equipped with a phase state monitoring component, which includes an ultrasonic transmitter and an ultrasonic receiver respectively placed on the upper and lower walls of each chamber, and monitors the phase state in the chamber in real time through sound wave monitoring.
[0011] Preferably, the top of the device housing is provided with a medium inlet and a medium outlet, and the finned tubes in each chamber are simultaneously connected to the medium inlet and the medium outlet; the heat exchange medium enters through the medium inlet, flows through each chamber in sequence, and then flows out through the medium outlet.
[0012] Preferably, each chamber is provided with a vertical guide pipe that is connected to the heat exchange medium pipeline, which is used to guide the heat exchange medium into the bottom of the chamber and flow from bottom to top along the heat exchange medium pipeline.
[0013] Preferably, the outer shell of the device is a rectangular box structure, and the exterior is made of thermal insulation material.
[0014] Preferably, the heat exchange medium pipeline is a coil with bends and fins uniformly welded to the outside of the pipeline. The fin thickness is 1.5 mm, the pitch is 15 mm, and the fin width is 10 mm.
[0015] Preferably, the heat exchange medium pipeline remains sealed where it passes through the partition layer, so that each chamber forms an independent sealed space.
[0016] Preferably, the phase monitoring component is arranged in the chamber with the worst heat exchange or in each chamber, with the generated waves in different chambers having different frequencies.
[0017] Preferably, the chamber is further provided with foamed metal, which is combined with the phase change material to enhance heat transfer; or nanoparticles are added to the phase change material to enhance heat transfer.
[0018] To address the issue that the heat release rate gradually decreases with increasing heat release time during the re-release of stored heat, this invention combines a multi-cascade device and uses an acoustic wave transmitting and receiving device to monitor the molten salt state within each cavity. By monitoring changes in the molten salt phase state, the time for heat storage and release is precisely controlled. Preferably, the device comprises multiple independent box-type housings connected to the same distribution device, through which the heat exchange medium is evenly distributed to each housing.
[0019] Preferably, a solenoid valve is installed at the medium inlet of the device housing, and a thermocouple for detecting fluid temperature is provided in the medium outlet pipeline.
[0020] Compared with the prior art, the innovative aspects and beneficial effects of this invention are as follows:
[0021] (1) Existing molten salt thermal energy storage mainly focuses on sensible heat storage, while the utilization of latent heat can greatly increase the amount of heat stored. Compared with ordinary latent heat thermal energy storage devices, the containerized layout can greatly improve space utilization and reduce the placement problem of thermal energy storage units.
[0022] (2) By combining the container-type layout with multi-level devices, the phase change time of each section is kept the same as much as possible, and the temperature difference between the phase change temperature and the actual temperature of the pipeline is kept basically consistent. This can make the power of charging / discharging more stable and reduce the problem that the heat exchange temperature difference decreases as the charging / discharging time increases.
[0023] (3) It is designed with a relatively convenient connection method, which can easily expand the heat storage capacity when the heat storage capacity is increased. It only requires increasing the number of boxes and making simple pipeline connections (parallel connection).
[0024] (4) In order to provide timely feedback on the end of heat storage and release, the phase state in the chamber was monitored in real time by means of acoustic monitoring. Attached Figure Description
[0025] Figure 1 Schematic diagram of a compact molten salt heat exchanger and molten salt phase detection device;
[0026] Figure 2 Schematic diagram of finned tube arrangement (left view);
[0027] Figure 3Detailed image of the fins;
[0028] Figure 4 This is a schematic diagram of the overall process of the parallel connection of the devices. Detailed Implementation
[0029] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the invention is not limited to the specific embodiments disclosed below.
[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0031] like Figure 1-3 The compact molten salt heat exchange and molten salt phase detection device shown mainly consists of three parts: the device shell 5 and the partition layer 11, the finned tube 1, and the phase monitoring component.
[0032] In this specific embodiment, the molten salt heat exchange and molten salt phase detection device includes a box-shaped outer shell 5, which is divided into multiple independent chambers by a partition layer 11. Each chamber is filled with a phase change material 6 with a different phase change temperature. Each chamber is equipped with a finned tube 1, which includes a heat exchange medium pipe 1-1 and fins 1-2 located on the outside of the pipe. The finned tubes 1 in each chamber are connected in series, and the heat exchange medium entering each chamber flows from bottom to top in the heat exchange medium pipe.
[0033] At least some of the chambers are equipped with phase state monitoring components to provide timely feedback on the end of heat storage and release. The phase state monitoring components include ultrasonic transmitters 10 and ultrasonic receivers 2, which are respectively placed on the upper and lower walls of each chamber, to monitor the phase state in the chamber in real time through sound wave monitoring.
[0034] The device in this embodiment has a container-like structure, and the exterior is made of thermal insulation material.
[0035] The outer shell 5 of the device is generally a steel structure, made of carbon steel. It is designed as a cuboid, cube, or other easily assembled structure, with a thickness of more than 10 mm to ensure safety. Since molten salt is corrosive to steel materials, the expected design life should be considered during the design process. For devices with long design life and many cycles, the thickness of the covering material should be appropriately increased or the material should be replaced and optimized.
[0036] The difference between the phase change materials on both sides of the internal partition layer 11 should also be considered. The temperature and corrosivity on both sides will also be different. For multiple cycles, thermal stress should be checked to avoid large thermal stress deformation during use, which may reduce the volume of some cavities and cause molten salt leakage due to insufficient volume during heat storage.
[0037] In this embodiment, the outer casing 5 schematically divides the entire heat exchange section into four independent chambers by the partition layer 11. In practical applications, the size and number of each chamber can be redefined according to the actual length of the heat exchange tubes. Each chamber should be filled with phase change materials (6-9) with different phase change temperatures. In a more preferred embodiment, foamed metal is also arranged in the chamber, combined with the phase change material to enhance heat exchange; or nanoparticles are added to the phase change material to enhance heat exchange.
[0038] The top of the device housing 5 is provided with a medium inlet 3 and a medium outlet 4. The finned tubes 1 in each chamber are simultaneously connected to the medium inlet and the medium outlet. The heat exchange medium enters through the medium inlet 3, flows through the finned tubes 1 in each chamber in sequence, and then flows out through the medium outlet 4.
[0039] like Figure 2 The finned tubes 1 shown are installed in each chamber. Pre-installed heat exchange medium pipes 1-1 connect to the medium inlet 3 and the medium outlet 4. The heat exchange medium is typically a fluid such as heat transfer oil or water. The pipes are arranged in a coiled manner using bends to maximize the heat exchange area per unit volume. Fins 1-2 are uniformly welded to the outside of the pipes and must be fully welded to prevent gaps between the fins and the pipes, which would increase contact thermal resistance.
[0040] In this embodiment, the fin thickness is 1.5 mm, the pitch is 15 mm, and the fin width is 10 mm. Because copper is relatively expensive, carbon steel is generally chosen for the fins and pipes, as it also offers good heat exchange performance.
[0041] The heat exchange medium pipe 1-1 remains sealed where it passes through the partition layer 11, so that each chamber forms an independent sealed space. The finned tube 1 needs to pass through the partition layer 11 for connection. Therefore, at the bend, the pipe is a bare pipe without fins. Since the phase change materials on both sides are different, in order to keep the material properties as constant as possible, the pipe opening of the partition layer needs to be strictly sealed.
[0042] Each chamber is equipped with a vertical guide pipe connected to the heat exchange medium pipeline 1-1, which guides the heat exchange medium into the bottom of the chamber and flows upward along the heat exchange medium pipeline. Since the attached diagram is drawn from the front, it should be noted that the device is vertically arranged. Because the density of the phase change material decreases after melting, it will float under gravity, generating natural convection, which further enhances heat exchange. Therefore, the pipeline arrangement is such that after entering from the medium inlet 3, it should first flow through the lower pipeline. An additional vertical guide pipe needs to be arranged in each chamber to ensure the heat exchange medium flows upward.
[0043] The phase state monitoring component mainly includes an ultrasonic transmitter 10 and an ultrasonic receiver 2. The transmitter and receiver should be placed on the upper and lower walls of each chamber, respectively. Since the propagation speed of sound waves in solids and liquids is different, the sound velocity of the solid and liquid phases of each phase change material can be tested in advance. The data can be converted according to the design dimensions to calculate the sound wave propagation time when the phase change material is completely converted into the liquid phase. The system can then be connected to a computer for signal monitoring.
[0044] The placement should also be closer to areas where heat diffusion is more difficult, such as the leftmost chamber, away from the heat exchange medium inlet. Other chambers should also have their walls on the side with the lower phase change temperature measured similarly.
[0045] In this embodiment, during operation, the heat exchange medium first enters the device through medium inlet 3, passes through a guide pipe to reach the bottom layer, and then flows along the pipe in the first chamber for heat exchange until it reaches the top of the first chamber. Due to the higher temperature of the molten salt at the bottom, it melts faster, generating natural convection to accelerate heat exchange. Afterward, it passes through a partition layer and then flows upward from the bottom of the second chamber through a vertical guide pipe for heat exchange. However, since the first chamber has already absorbed some heat, the temperature of the heat exchange medium in the second chamber will decrease. Therefore, the phase change temperature of the phase change material in this chamber should be appropriately lowered. The heat exchange medium then flows sequentially through each chamber until it exits the casing through medium outlet 4, completing the heat exchange process.
[0046] During the heat storage process, ultrasonic receivers can be set to a specific frequency and can be placed either only in the chamber with the worst heat exchange or in every chamber. The generated waves in different chambers can be set to different frequencies. The heat release process involves the phase change material transforming from a liquid to a solid state. During this process, the volume of the phase change material decreases, and a significant amount of air is regenerated at the top. It is sufficient to record the time from ultrasonic wave emission to reception before heat storage begins. The state at the end of heat release is essentially the same as the state before heat storage begins.
[0047] The specific implementation method is to determine the total number of chambers required based on the size of the heat storage volume. The total amount of heat storage required can be calculated by dividing the total heat storage by the heat storage of a single chamber. The heat storage of a single chamber needs to be determined according to the application. For example, if the application is in a medium temperature range, several phase change materials with different phase change temperatures are used for filling. The phase change enthalpy of the material is constant. It is only necessary to accurately measure the mass of the phase change material in different cascades to determine the total heat storage of each chamber.
[0048] In such Figure 4 In another embodiment shown, it is necessary to... Figure 1 When multiple housings of the structure shown are used in combination, a distribution device should be installed at the heating outlet of the heat exchange medium to evenly distribute the heat exchange medium to the inlet of each housing. All heat exchange medium flowing through the housings can be returned to the heat exchanger via a pump and pipeline by adding a container for the heat exchange medium. In other words, this device comprises multiple independent housing units connected to the same distribution device, through which the heat exchange medium is evenly distributed to each housing unit.
[0049] The piping in each chamber is interconnected, and the hot fluid flows from bottom to top. For example... Figure 4 As shown, the high-temperature heat exchange fluid flows out from the thermal oil boiler 2-1 (in practice, it can be other devices, such as high-temperature water or steam in a boiler), flows into different chambers 2-5 through fluid pipeline 2-2, and the chambers are connected in parallel. Four chambers are shown in the figure for illustration. After exchanging heat with the phase change material in 2-5, the fluid flows back to 2-1 through pipeline 2-2. 2-3 is a solenoid valve, which can open and close upon detecting a specific electrical signal. 2-4 is a thermocouple placed in the pipeline, which accurately reflects the fluid temperature. When thermocouple 2-4 transmits the temperature back to computer 2-6 through line 2-7, the average temperature of the fluid after heat exchange can be calculated in real time using certain software. When the average temperature of the fluid is higher than the initially set temperature threshold, an electrical signal is sent to open the solenoid valve of the next chamber, thereby stabilizing the heat exchange power.
[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A compact molten salt heat exchange and molten salt phase detection device, characterized in that, It includes a box-shaped outer shell, inside which are divided into multiple chambers by a partition layer, and each chamber is filled with a phase change material with a different phase change temperature; Each chamber is equipped with a finned tube, which includes a heat exchange medium pipe and fins located on the outside of the pipe; the finned tubes in each chamber are connected in series, and the heat exchange medium entering each chamber flows from bottom to top in the heat exchange medium pipe; The chamber is equipped with a phase state monitoring component, which includes an ultrasonic transmitter and an ultrasonic receiver respectively placed on the upper and lower walls of each chamber, and monitors the phase state in the chamber in real time through sound wave monitoring.
2. The compact molten salt heat exchange and molten salt phase detection device according to claim 1, characterized in that, The top of the device housing is provided with a medium inlet and a medium outlet, and the finned tubes in each chamber are simultaneously connected to the medium inlet and the medium outlet; the heat exchange medium enters through the medium inlet, flows through each chamber in sequence, and then flows out through the medium outlet.
3. The compact molten salt heat exchange and molten salt phase detection device according to claim 2, characterized in that, Each chamber is equipped with a vertical guide pipe that is connected to the heat exchange medium pipeline, which is used to guide the heat exchange medium into the bottom of the chamber and flow from bottom to top along the heat exchange medium pipeline.
4. The compact molten salt heat exchange and molten salt phase detection device according to claim 1, characterized in that, The device has a rectangular box-shaped outer shell, and the exterior is made of thermal insulation material.
5. The compact molten salt heat exchange and molten salt phase detection device according to claim 4, characterized in that, The heat exchange medium pipeline is a coiled tube arranged in bends, with fins uniformly welded to the outside of the pipeline. The fins are 1.5mm thick, 15mm pitch, and 10mm wide.
6. The compact molten salt heat exchange and molten salt phase detection device according to claim 1, characterized in that, The heat exchange medium pipeline remains sealed where it passes through the partition layer, so that each chamber forms an independent sealed space.
7. The compact molten salt heat exchange and molten salt phase detection device according to claim 1, characterized in that, The phase monitoring component is arranged in the chamber with the worst heat exchange or in each chamber, and the generated waves in different chambers are at different frequencies.
8. The compact molten salt heat exchange and molten salt phase detection device according to claim 1, characterized in that, The chamber is also filled with foamed metal, which is combined with the phase change material to enhance heat transfer; or nanoparticles are added to the phase change material to enhance heat transfer.
9. The compact molten salt heat exchange and molten salt phase detection device according to claim 1, characterized in that, It includes multiple independent box-type housings connected to the same distribution device, through which the heat exchange medium is evenly distributed to each housing unit.
10. The compact molten salt heat exchange and molten salt phase detection device according to claim 9, characterized in that, A solenoid valve is installed at the medium inlet of the device housing, and a thermocouple for detecting fluid temperature is installed in the medium outlet pipeline.