A dual-phase change direct contact reversible phase change heat storage system and its control method

Abstract

The present invention relates to the field of phase change heat storage technology, disclosing a dual-phase change, direct-contact, reversible phase change heat storage system and its control method. The system includes a support frame, a rotating mechanism, and a heat storage tank. The heat storage tank is rotatably connected to the support frame via the rotating mechanism. The inner cavity of the heat storage tank is divided into a heat carrier fluid gas-liquid phase change zone and a phase change heat storage material zone. The heat carrier fluid gas-liquid phase change zone is located above the phase change heat storage material zone. The phase change heat storage material zone contains a mixed phase change heat storage material and heat storage liquid. The heat storage tank is provided with a heat exchange tube, the ends of which are respectively fixed to the two outer walls of the heat storage tank and extend into the heat carrier fluid gas-liquid phase change zone. The present invention has a large heat exchange capacity, a short heat storage and release time, and a simple and uncomplicated structure.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change heat storage technology, and in particular to a dual-phase change direct contact reversible phase change heat storage system and a control method thereof. Background Art

[0002] The series of issues brought about by the energy and environmental crises are attracting increasing attention. Developing new green energy sources and improving energy utilization efficiency are key research priorities. Currently, solar energy is a major new energy source of particular interest, but there is a temporal and spatial mismatch between solar energy utilization and waste heat recovery. Phase change energy storage materials can absorb and release energy from the environment, effectively resolving this temporal and spatial mismatch between energy supply and demand and significantly improving energy utilization. The unique characteristics of phase change heat storage systems offer broad application prospects in areas such as peak-to-valley shifting, industrial and civil construction, air conditioning energy conservation, and military applications.

[0003] However, the existing phase change heat storage system has the following technical problems:

[0004] The heat exchange capacity in phase change heat storage is small, and the heat storage and heat release time is long;

[0005] The risk of leakage of heat storage materials in phase change heat storage devices;

[0006] The phase change heat storage device has a complex structure. Summary of the Invention

[0007] In response to the above technical problems, the present invention aims to provide a dual-phase change direct-contact reversible phase change heat storage system and a control method thereof, so as to solve the above technical problems through a new design.

[0008] The present invention is achieved by adopting the following technical solutions:

[0009] A dual-phase change direct-contact reversible phase change heat storage system includes a support frame, a rotating mechanism and a heat storage tank. The heat storage tank is rotatably connected to the support frame via the rotating mechanism. The inner cavity of the heat storage tank is divided into a heat carrier fluid gas-liquid phase change zone and a phase change heat storage material zone. The heat carrier fluid gas-liquid phase change zone is located above the phase change heat storage material zone. The phase change heat storage material zone is provided with a mixed phase change heat storage material and heat storage liquid. The heat storage tank is provided with a heat exchange pipe. The two ends of the heat exchange pipe are respectively fixed to the two outer walls of the heat storage tank. The heat exchange pipe extends into the heat carrier fluid gas-liquid phase change zone.

[0010] Advantageously, the heat exchange tube is provided with two or more fins.

[0011] Advantageously, the heat exchange tube is spiral-shaped, one end of the heat exchange tube is fixedly connected to the top wall of the heat storage tank, and the other end of the heat storage tank is fixedly connected to the side wall of the heat storage tank.

[0012] Advantageously, the outer diameter of the spiral gradually increases from top to bottom.

[0013] Advantageously, the top wall of the heat storage tank is provided with a first pipe box and a second pipe box, and there are more than two heat exchange tubes, one end of the heat exchange tube is fixedly connected to the first pipe box, and the other end of the heat exchange tube is fixedly connected to the second pipe box.

[0014] Advantageously, the heat exchange tube is wavy.

[0015] Advantageously, the heat exchange tube is U-shaped.

[0016] Advantageously, the rotating mechanism includes a rotating shaft, a movable gear and a fixed clip, the rotating shaft is fixed to the support frame, the movable gear is rotatably connected to the rotating shaft, the movable gear is fixed to the heat storage tank, the fixed clip is detachably connected to the movable gear, and the fixed clip is used to limit the rotation between the movable gear and the rotating shaft.

[0017] Advantageously, two baffles with holes are provided in the gas-liquid phase change zone of the heat-carrying fluid, and a safety valve and a monitoring device are also provided on the heat storage tank.

[0018] A control method for a dual-phase-change direct-contact reversible phase-change heat storage system comprises the following steps:

[0019] When the phase change heat storage system performs heat storage operation:

[0020] The phase change heat storage material is placed in the phase change heat storage material area filled with the heat storage liquid without any gap. The phase change heat storage material and the heat storage liquid are in direct contact and mixing. In the heat storage working condition, the heat storage tank needs to be inverted, that is, the gas-liquid phase change area of ​​the heat carrier fluid is located below the phase change heat storage material area. The heat storage tank is turned 180 degrees by the rotating mechanism on the support frame, and the external liquid inlet pipe is connected to one end of the heat exchange tube, and the external liquid outlet pipe is connected to the other end of the heat exchange tube. The hot fluid enters the heat exchange tube from the liquid inlet pipe. After the gas-liquid phase change area of ​​the heat carrier fluid is in direct contact with the heat exchange tube, the air in the gas-liquid phase change area of ​​the heat carrier fluid is heated, so that the heat storage solution is heated to the phase change point of the phase change heat storage material, causing the phase change heat storage material to undergo a phase change, thereby utilizing the phase change heat storage material to store potential energy in the liquid and solid phase changes;

[0021] When the phase change heat storage system is performing heat release operation:

[0022] Disconnect the external liquid inlet pipe and the external liquid outlet pipe from the heat exchange pipe respectively, and flip the heat storage box again 180 degrees through the rotating mechanism on the support frame, and place the heat storage box upright, that is, the gas-liquid phase change zone of the heat carrier fluid is located above the phase change heat storage material area. Then connect the external liquid inlet pipe to one end of the heat exchange pipe, and connect the external liquid outlet pipe to the other end of the heat exchange pipe. At this time, the external liquid inlet pipe flows low-temperature fluid into the heat exchange pipe, and the heat storage liquid in the phase change heat storage material area is a high-temperature liquid. The air in the gas-liquid phase change zone of the heat carrier fluid rises in temperature after contacting the heat storage liquid. The air in the gas-liquid phase change zone of the heat carrier fluid is heated and rises, contacts the heat exchange pipe and condenses. After condensation, the liquid falls back into the phase change heat storage material area and then continues the heat storage process.

[0023] The present invention has the following beneficial effects:

[0024] 1. The phase change heat storage system and control method provided by the present invention have direct contact heat storage without wall heat conduction resistance and high heat transfer coefficient, thereby realizing high heat flux density heat storage. Condensation heat transfer is to transfer heat to the fluid in the tube, and the tubes are equipped with fins to increase the heat exchange area, thereby achieving the purpose of high heat flux heat release.

[0025] 2. The phase change heat storage system and control method provided by the present invention are not affected by wall resistance because of the dual-phase change direct contact heat storage. Because there is direct contact between solid-liquid and gas-liquid phase changes, large heat flow heat exchange can be achieved, thereby effectively solving the problems of low heat exchange capacity and long heat storage and release time of phase change heat storage.

[0026] 3. The phase change heat storage system and control method provided by the present invention have two areas for heat exchange and storage, namely the gas-liquid phase change area of ​​the heat carrier fluid and the phase change heat storage material area. This greatly increases the heat exchange capacity of the system, thereby saving the time of charging and discharging heat and improving system efficiency. The two areas are clearly divided, and the integrated design of the heat storage tank has good sealing performance, so the heat storage material is not easy to leak. In addition, the three device modes provided by the present invention have a simple structure and are easy to move, thus greatly optimizing the structural complexity and inconvenience of mobility of previous direct contact phase change heat storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0028] Figure 1 2 is a schematic structural diagram of a dual-phase-change direct-contact phase-change heat storage system according to an embodiment of the present invention;

[0029] Figure 2 This invention Figure 1 A top view of

[0030] Figure 3 2 is a schematic structural diagram of a dual-phase-change direct-contact phase-change heat storage system according to an embodiment of the present invention;

[0031] Figure 4 This invention Figure 3 A top view of

[0032] Figure 5 2 is a schematic structural diagram of a dual-phase-change direct-contact phase-change heat storage system according to an embodiment of the present invention;

[0033] Figure 6 This invention Figure 5 A top view of

[0034] Figure 7 This invention Figure 1 Schematic diagram of the structure of the parallel state of the middle heat storage tank;

[0035] Figure 8 This invention Figure 7 Schematic diagram of the structure of the middle heat storage tank after it is turned 180 degrees;

[0036] Figure 9 This invention Figure 1 Structural diagram of the middle heat storage tank in series connection;

[0037] Figure 10 This invention Figure 9 Schematic diagram of the structure of the middle heat storage tank after it is turned 180 degrees;

[0038] Figure 11 This invention Figure 1 Schematic diagram of the structure of the baffle with holes in the middle.

[0039] Figure numerals: support frame 1, heat storage box 2, heat carrier fluid gas-liquid phase change zone 21, phase change heat storage material zone 22, phase change heat storage material 3, heat exchange tube 4, fin 5, first tube box 6, second tube box 7, rotating shaft 8, movable gear 9, fixing buckle 10, perforated baffle 11, safety valve 12, monitoring device 13. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] In the description of the present invention, it should be noted that the terms "vertical," "upper," "lower," and "horizontal," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] It should also be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0043] Example

[0044] like Figures 1-10 As shown, the dual-phase change direct-contact reversible phase change heat storage system provided by the embodiment of the present invention includes a support frame 1, a rotating mechanism and a heat storage tank 2. The heat storage tank 2 is rotatably connected to the support frame 1 through the rotating mechanism. The inner cavity of the heat storage tank 2 is divided into a heat carrier fluid gas-liquid phase change zone 21 and a phase change heat storage material zone 22. The heat carrier fluid gas-liquid phase change zone 21 is located above the phase change heat storage material zone 22. The phase change heat storage material zone 22 is provided with a phase change heat storage material 3 and a heat storage liquid mixed with each other. A heat exchange tube 4 is provided on the heat storage tank 2. The two ends of the heat exchange tube 4 are respectively fixed to the two outer walls of the heat storage tank 2, and the heat exchange tube 4 extends into the heat carrier fluid gas-liquid phase change zone 21.

[0045] In an optional embodiment of the present invention, the heat exchange tube 4 is provided with two or more fins 5 .

[0046] In an optional embodiment of the present invention, the heat exchange tube 4 is spiral, one end of the heat exchange tube 4 is fixed to the top wall of the heat storage tank 2, and the other end of the heat storage tank 2 is fixed to the side wall of the heat storage tank 2. Figure 3 、 4 shown.

[0047] In an optional embodiment of the present invention, the outer diameter of the spiral gradually increases from top to bottom.

[0048] In an optional embodiment of the present invention, a first pipe box 6 and a second pipe box 7 are provided on the top wall of the heat storage tank 2, and more than two heat exchange tubes 4 are provided, one end of the heat exchange tube 4 is fixedly connected to the first pipe box 6, and the other end of the heat exchange tube 4 is fixedly connected to the second pipe box 7.

[0049] In an optional embodiment of the present invention, the heat exchange tube 4 is wavy. Figure 5 、 6 shown.

[0050] In an optional embodiment of the present invention, the heat exchange tube 4 is U-shaped. Figure 1 、 2 , 7, , 8, 9, and 10.

[0051] In an optional embodiment of the present invention, the rotating mechanism includes a rotating shaft 8, a movable gear 9 and a fixed clip 10, the rotating shaft 8 is fixed to the support frame 1, the movable gear 9 is rotatably connected to the rotating shaft 8, the movable gear 9 is fixed to the heat storage tank 2, and the fixed clip 10 is detachably connected to the movable gear 9, and the fixed clip 10 is used to limit the rotation between the movable gear 9 and the rotating shaft 8.

[0052] In an optional embodiment of the present invention, two perforated baffles 11 are provided within the heat carrier fluid gas-liquid phase change zone 21, and the heat storage tank 2 is also provided with a safety valve 12 and a monitoring device 13. The addition of the safety valve 12 prevents deformation of the heat storage tank 2 due to excessive pressure during the phase change of the heat carrier fluid gas-liquid phase change zone 21. The addition of the perforated baffles 11, the perforated baffles 11 near the heat exchange tubes 4, is intended to prevent the phase change heat storage material 3 from falling off and damaging the heat exchange tubes 4 during charging. The perforated baffles 11 near the heat carrier fluid gas-liquid phase change zone 21 are intended to secure the phase change heat storage material 3 at the bottom. The monitoring device 13 facilitates user monitoring of various conditions within the heat storage tank 2. The monitoring device 13 can be a pressure probe with an indicator, a temperature probe with an indicator, or a combination of both.

[0053] A control method based on the aforementioned dual-phase change direct contact phase change heat storage system comprises the following steps:

[0054] When the phase change heat storage system performs heat storage operation:

[0055] The phase change heat storage material 3 is placed in the phase change heat storage material area 22 filled with the heat storage liquid, without any gap. The phase change heat storage material 3 is in direct contact and mixing with the heat storage liquid. In the heat storage working condition, the heat storage tank 2 needs to be inverted, that is, the heat carrier fluid gas-liquid phase change area 21 is located below the phase change heat storage material area 22. The heat storage tank 2 is turned 180 degrees by the rotating mechanism on the support frame 1, and the external liquid inlet pipe is connected to one end of the heat exchange tube 4, and the external liquid outlet pipe is connected to the other end of the heat exchange tube 4. The hot fluid enters the heat exchange tube 4 from the liquid inlet pipe, and the heat storage solution is heated to the phase change point of the phase change heat storage material 3, causing the phase change heat storage material 3 to undergo a phase change, thereby utilizing the phase change heat storage material 3 to store the potential energy in the liquid and solid phase changes;

[0056] When the phase change heat storage system is performing heat release operation:

[0057] The external liquid inlet pipe and the external liquid outlet pipe are disconnected from the heat exchange pipe 4 respectively, and the heat storage tank 2 is turned over again by 180 degrees through the rotating mechanism on the support frame 1. The heat storage tank 2 is placed upright, that is, the gas-liquid phase change zone 21 of the heat-carrying fluid is located above the phase change heat storage material zone 22. Then, the external liquid inlet pipe is connected to one end of the heat exchange pipe 4, and the external liquid outlet pipe is connected to the other end of the heat exchange pipe 4. At this time, the external liquid inlet pipe flows low-temperature fluid into the heat exchange pipe 4, and the phase change heat storage material zone 22 generates high-temperature gas. The high-temperature gas rises to contact with the heat exchange pipe 4 and condenses. After condensation, the liquid falls back into the phase change heat storage material zone 22 and the heat storage process continues.

[0058] More specific control process steps are:

[0059] When the phase change heat storage system is to store heat and enter the heat storage state, the phase change heat storage material 3 is placed in the phase change heat storage material area 22 filled with the heat storage liquid, without any interval, and the phase change heat storage material 3 is in direct contact with the heat storage liquid and mixed. In the heat storage working condition, the heat storage tank 2 needs to be inverted, that is, the heat carrier fluid gas-liquid phase change area 21 is located below the phase change heat storage material area 22, and the fixing buckle 10 is pulled out to allow the movable gear 9 to rotate smoothly on the rotating shaft 8, and the heat storage tank 2 is turned over 180 degrees, and then The fixing buckle 10 is reinserted into the movable gear 9 for positioning, and the external liquid inlet pipe is connected to one end of the heat exchange tube 4, and the external liquid outlet pipe is connected to the other end of the heat exchange tube 4. The hot fluid enters the heat exchange tube 4 from the liquid inlet pipe. After the gas-liquid phase change zone 21 of the heat-carrying fluid directly contacts the heat exchange tube 4, the air in the gas-liquid phase change zone 21 of the heat-carrying fluid is heated, so that the heat storage solution is heated to the phase change point of the phase change heat storage material 3, causing the phase change heat storage material 3 to undergo a phase change, thereby utilizing the phase change heat storage material 3 to store the potential energy in the liquid and solid phase changes;

[0060] To make the phase change heat storage system release heat and enter the heat release state:

[0061] Close the valves on the external liquid inlet pipe and the external liquid outlet pipe, disconnect the external liquid inlet pipe and the external liquid outlet pipe from the heat exchange tube 4 respectively, pull out the fixing clip 10, so that the movable gear 9 can rotate smoothly on the rotating shaft 8, and use the rotating mechanism on the support frame 1 to turn the heat storage tank 2 again by 180 degrees. Then reinsert the fixing clip 10 into the movable gear 9 to limit it. Place the heat storage tank 2 upright, that is, the gas-liquid phase change zone 21 of the heat carrier fluid is located above the phase change heat storage material zone 22. Then connect the external liquid inlet pipe to one end of the heat exchange tube 4, and connect the external liquid outlet pipe to the other end of the heat exchange tube 4. At this time, the external liquid inlet pipe flows low-temperature fluid into the heat exchange tube 4, and the heat storage liquid in the phase change heat storage material zone 22 is a high-temperature liquid. The air in the gas-liquid phase change zone 21 of the heat carrier fluid heats up after contacting the heat storage liquid. The air in the gas-liquid phase change zone 21 of the heat carrier fluid rises due to the heat and contacts the heat exchange tube 4 to condense. After condensation, the liquid falls back into the phase change heat storage material zone 22 and the heat storage process continues.

[0062] When a first pipe box 6 and a second pipe box 7 are provided, the external liquid inlet pipe is connected to the first pipe box 6 so that the external liquid inlet pipe can communicate with all the heat exchange tubes 4, and the external liquid outlet pipe is connected to the second box 7 so that the external liquid outlet pipe can communicate with all the heat exchange tubes 4.

[0063] The cover of the heat exchange tube 4 and the heat storage tank 2 can be connected by flanges to facilitate loading and unloading.

[0064] The phase change heat storage system provided by the present invention has direct contact heat storage without wall heat conduction resistance and a high heat transfer coefficient, thereby realizing high heat flux density heat storage. Condensation heat exchange is to transfer heat to the fluid in the tube, and the tubes are equipped with fins to increase the heat exchange area, thereby achieving the purpose of high heat flux heat release.

[0065] The present invention is not affected by wall resistance because of the dual-phase change direct contact heat storage, and because of the direct contact of solid-liquid and gas-liquid dual-phase changes, it can achieve large heat flow heat exchange, thereby effectively solving the problems of small phase change heat exchange capacity and long heat storage and release time.

[0066] Since the present invention has two areas for heat exchange and storage, namely the heat carrier fluid gas-liquid phase change area 21 and the phase change heat storage material area 22, the heat exchange capacity of the system is greatly increased, thereby saving the time for charging and discharging heat and improving the system efficiency. The two areas are clearly divided, and the integrated design of the heat storage tank 2 has good sealing performance, so the heat storage material is not easy to leak. In addition, the three device modes provided by the present invention are simple in structure and easy to move, thereby greatly optimizing the structural complexity and inconvenience of moving of the previous direct contact phase change heat storage.

[0067] The components, modules, mechanisms and devices not described in detail in the present invention are all universal standard parts or components known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A dual-phase change direct contact reversible phase change heat storage system, characterized by: The invention comprises a support frame (1), a rotating mechanism and a heat storage tank (2); the heat storage tank (2) is rotatably connected to the support frame (1) via the rotating mechanism; the inner cavity of the heat storage tank (2) is divided into a heat-carrying fluid gas-liquid phase change zone (21) and a phase-change heat storage material zone (22); the heat-carrying fluid gas-liquid phase change zone (21) is located above the phase-change heat storage material zone (22); the phase-change heat storage material zone (22) is provided with a phase-change heat storage material (3) and a heat storage liquid that are mixed with each other; a heat exchange tube (4) is provided on the heat storage tank (2); the two ends of the heat exchange tube (4) are respectively fixed to the two outer walls of the heat storage tank (2); and the heat exchange tube (4) extends into the heat-carrying fluid gas-liquid phase change zone (21).

2. The dual-phase change direct contact reversible phase change heat storage system according to claim 1 is characterized in that: The heat exchange tube (4) is provided with two or more fins (5).

3. The dual-phase change direct contact reversible phase change heat storage system according to claim 2 is characterized in that: The heat exchange tube (4) is spiral-shaped, one end of the heat exchange tube (4) is fixedly connected to the top wall of the heat storage tank (2), and the other end of the heat exchange tube (4) is fixedly connected to the side wall of the heat storage tank (2).

4. The dual-phase change direct contact reversible phase change heat storage system according to claim 3 is characterized in that: The outer diameter of the spiral gradually increases from top to bottom.

5. The dual-phase change direct contact reversible phase change heat storage system according to claim 2 is characterized in that: The top wall of the heat storage box (2) is provided with a first pipe box (6) and a second pipe box (7), and two or more heat exchange tubes (4) are provided. One end of the heat exchange tube (4) is fixedly connected to the first pipe box (6), and the other end of the heat exchange tube (4) is fixedly connected to the second pipe box (7).

6. The dual-phase change direct contact reversible phase change heat storage system according to claim 5 is characterized in that: The heat exchange tube (4) is wavy.

7. The dual-phase change direct contact reversible phase change heat storage system according to claim 5, characterized in that: The heat exchange tube (4) is U-shaped.

8. The dual-phase change direct contact reversible phase change heat storage system according to claim 1 is characterized in that: The rotating mechanism comprises a rotating shaft (8), a movable gear (9) and a fixed buckle (10); the rotating shaft (8) is fixedly connected to the support frame (1); the movable gear (9) is rotatably connected to the rotating shaft (8); the movable gear (9) is fixedly connected to the heat storage tank (2); the fixed buckle (10) is detachably connected to the movable gear (9); and the fixed buckle (10) is used to limit the rotation between the movable gear (9) and the rotating shaft (8).

9. The dual-phase change direct contact reversible phase change heat storage system according to claim 1, characterized in that: A baffle with holes (11) is provided in the gas-liquid phase change zone (21) of the heat-carrying fluid, and a safety valve (12) and a monitoring device (13) are also provided on the heat storage tank (2).

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