Phase change heat storage tank with graphite blocks

Abstract

The invention discloses a phase change heat storage tank with graphite blocks, and belongs to the technical field of phase change heat storage, the heat storage tank comprises an outer shell, a thermal insulation layer, an inner shell, a phase change heat storage medium, a graphite block group and a heat exchange tube, the heat exchange tube comprises a heat exchange section immersed in the phase change heat storage medium, and the graphite block group comprises a base plate, a pressing plate and a plurality of graphite blocks. The graphite block set is arranged, the total weight of the heat storage tank is reduced, and the heat storage rate is increased; the inner shell is made of a graphite material and does not react with the metal phase change material; the positions of the graphite block groups can be limited, so that the graphite blocks are prevented from being accumulated due to unfixed positions, uniform transfer of heat of the phase-change heat storage medium is ensured, and stable heat storage rate is ensured; the heat storage rate and the heat storage capacity of the phase change heat storage medium are influenced by adjusting the number of the graphite blocks, and then the heat storage rate and the heat storage capacity of the whole heat storage tank are changed so as to meet different use requirements.

Description

Technical Field

[0001] This invention belongs to the field of phase change thermal energy storage technology, specifically relating to a phase change thermal energy storage tank with graphite blocks. Background Technology

[0002] Phase change thermal energy storage (PCE) tanks are devices that store and release thermal energy by absorbing or releasing latent heat through changes in the physical state of internal PCE materials (such as solid-liquid or liquid-solid phase changes). Because their heat storage capacity is significantly higher than traditional sensible heat storage methods, they are increasingly widely used in industrial waste heat recovery. Metal / alloy PCE materials are currently a common type of PCE material. They have high density and can store a large amount of heat per unit volume, giving them advantages in medium-high temperature and even low-temperature PCE applications. However, some problems remain. Due to the high density of metal PCE materials, their heat storage per unit mass is not advantageous, resulting in higher overall costs. Furthermore, some metal alloys have high chemical reactivity and are corrosive in the liquid phase, limiting the application of metal PCE tanks. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a phase change thermal storage tank with graphite blocks. By adding graphite blocks to the thermal storage tank, the overall weight of the thermal storage tank is reduced and the thermal storage rate of the thermal storage tank is increased.

[0004] Technical Solution: To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A phase change thermal storage tank with graphite blocks includes an outer shell, an insulation layer disposed within the outer shell, an inner shell disposed within the insulation layer, a phase change thermal storage medium disposed within the inner shell, a graphite block assembly disposed within the phase change thermal storage medium, and a heat exchange tube for exchanging heat with the phase change thermal storage medium. The heat exchange tube includes a heat exchange section immersed in the phase change thermal storage medium. The graphite block assembly includes a substrate, a pressure plate corresponding to the substrate, and a plurality of graphite blocks disposed between the substrate and the pressure plate.

[0006] Preferably, the substrate is provided with a first through hole corresponding to the heat exchange tube and a plurality of second through holes corresponding to the graphite block, and the pressure plate is provided with a third through hole corresponding to the heat exchange tube and a plurality of fourth through holes for the phase change heat storage medium to flow through.

[0007] Preferably, the substrate is provided with a support rod, and the pressure plate is provided with a rod groove corresponding to the support rod.

[0008] Preferably, the pressure plate is provided with a second limiting block, the inner wall of the inner shell is provided with a displacement groove corresponding to the second limiting block, and the inner wall of the inner shell is provided with a second limiting groove that is connected to the displacement groove and corresponds to the second limiting block.

[0009] Preferably, the substrate is provided with a first limiting block, and the inner wall of the inner shell is provided with a first limiting groove that is connected to the displacement groove and corresponds to the first limiting block.

[0010] Preferably, multiple graphite block groups are provided, and the multiple graphite block groups are arranged vertically at intervals.

[0011] Preferably, the plurality of second through holes are arranged in a ring array on the substrate, and the plurality of fourth through holes are arranged in a ring array on the pressure plate.

[0012] Preferably, the first through hole includes a first enlarged portion, and the third through hole includes a second enlarged portion, both of which are circular.

[0013] Preferably, the inner shell is made of graphite material.

[0014] Preferably, the phase change thermal storage medium is a metallic phase change material or an organic phase change material.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0016] 1. A graphite block assembly, including a substrate, a pressure plate, and multiple graphite blocks, is set up to occupy the space inside the heat storage tank, thereby reducing the amount of metal phase change material used, reducing the total weight of the heat storage tank, and the graphite blocks can improve the thermal conductivity of the metal phase change material and increase the heat storage rate.

[0017] 2. The inner shell is made of graphite material. Due to the chemical stability and high temperature resistance of graphite, it does not react with metal phase change materials at high temperatures and can improve the thermal conductivity of metal phase change materials.

[0018] 3. The graphite block group can be positioned to prevent the graphite blocks from accumulating due to their unpredictable location, thus ensuring uniform heat transfer of the phase change thermal storage medium and a stable heat storage rate. Multiple graphite block groups can be set up, and the number of graphite blocks in each group can be adjusted. By adjusting the number of graphite blocks, the heat storage rate and heat storage capacity of the phase change thermal storage medium at that location can be affected, thereby changing the heat storage rate and heat storage capacity of the entire thermal storage tank to adapt to different usage requirements.

[0019] 4. The distance between graphite block groups is adjustable, the position of the graphite block groups in the heat storage tank is adjustable, and the distance between the base plate and the pressure plate is adjustable. Different sizes of graphite blocks can be used to adapt to different phase change heat storage media to meet the needs of different heat storage rates and heat storage capacities.

[0020] 5. The base plate and pressure plate of the graphite block assembly are provided with through holes corresponding to the heat exchange tubes, which does not affect the installation of the heat exchange tubes. Graphite blocks of different positions and diameters will also not affect the installation of the heat exchange tubes, making it possible to obtain heat storage tanks with different heat storage rates and heat storage capacities. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of this utility model;

[0022] Figure 2 This is a schematic diagram of the graphite block assembly structure in Example 1;

[0023] Figure 3 This is a schematic diagram of the substrate structure in Example 1;

[0024] Figure 4 This is a schematic diagram of the pressure plate structure in Example 1;

[0025] Figure 5 This is a schematic diagram of the displacement groove and the second limiting groove structure in Embodiment 1;

[0026] Figure 6 This is a structural schematic diagram of Embodiment 2 of the present invention;

[0027] Figure 7 This is a schematic diagram of the substrate structure in Example 2;

[0028] Figure 8 This is a schematic diagram of the displacement groove, the first limiting groove, and the second limiting groove in Embodiment 2;

[0029] Figure 9 This is a schematic diagram of the graphite block assembly structure in Example 2. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0031] like Figure 1As shown, a phase change thermal storage tank with graphite blocks includes an outer shell 1, an insulation layer 2, an inner shell 3, a phase change thermal storage medium 4, and a graphite block assembly 5. The outer shell 1 is cylindrical in shape. The insulation layer 2 is disposed inside the outer shell 1, and the inner shell 3 is disposed inside the insulation layer 2. In this embodiment, both the outer shell 1 and the inner shell 3 are detachable. The inner shell 3 includes an inner shell body and an inner shell top 32. A flange is formed at the upper end of the inner shell body. The inner shell top 32 is detachably connected to the inner shell body by bolts. An aluminum silicate gasket is used as a sealing gasket at the connection. The inner shell body of the inner shell 3 is cylindrical. In this embodiment, the inner shell 3 is made of graphite material. The inner shell body is formed into a cylindrical shape using existing pressing molding and high-temperature sintering processes with graphite powder. After sintering, the porosity is reduced, the structural uniformity is improved, and it is resistant to metal liquid penetration. The inner shell body of the inner shell 3 forms a receiving space to accommodate the phase change thermal storage medium 4. The outer shell 1 includes an outer shell body and an outer shell top 12, which are detachably connected to the outer shell body by bolts. The insulation layer 2 is made of aluminum silicate fiber material and includes an insulation barrel body and an insulation top 22. The insulation top 22 is disposed inside the outer shell top 12 and connected to it. The inner shell 3's inner shell top 32 is connected to the inner shell body and then the outer shell top 12 is placed on top of it, thus the outer shell 1 as a whole insulates the inner shell 3. In this embodiment, the phase change heat storage medium 4 is an existing metal phase change material, such as a lead-bismuth alloy, with a melting point of 124°C, which melts to form a liquid metal. The heat exchange tube 6 is inserted into the phase change heat storage medium 4 for heat exchange with the phase change heat storage medium 4. The heat exchange tube 6 is connected to the top 32 of the inner shell. The heat exchange tube 6 includes a heat exchange section 63 immersed in the phase change heat storage medium 4. In this embodiment, the heat exchange section 63 is a U-shaped tube, with the inlet and outlet ends connected to the two ends of the heat exchange section 63, respectively. The inlet end of the heat exchange tube 6 is connected to an external heat source, such as the high-temperature exhaust gas pipe of a thermal power unit. The exhaust gas temperature is 120℃-180℃. The external heat source (exhaust gas) enters the heat storage tank through the heat exchange tube 6 and exchanges heat with the phase change heat storage medium 4, thereby heating the phase change heat storage medium 4. The lead-bismuth alloy phase changes into liquid to store heat. After heat exchange with the external heat source, the heat is discharged from the outlet end of the heat exchange tube 6. An existing thermocouple sensor is installed on the outer wall of the inner shell 3. The thermocouple sensor is used to monitor the temperature of the inner shell 3 (the thermocouple sensor is not shown in the figure).

[0032] like Figure 1 and Figure 2As shown, the graphite block assembly 5 is disposed within the phase change heat storage medium 4. In this embodiment, the graphite block assembly 5 includes a substrate 51, a pressure plate 52, multiple graphite blocks 53, and support rods 54. The substrate 51 is a circular plate with a diameter corresponding to the inner diameter of the inner shell 3. Two support rods 54 are connected to the lower end face of the substrate 51 to support the substrate 51. The support rods 54 are fixedly connected to the substrate 51 or detachably connected by a threaded connection. The substrate 51 is provided with a first through hole 511 and multiple second through holes 51. 2. Both the first through hole 511 and the second through hole 512 extend from the upper end face to the lower end face of the substrate 51. The first through hole 511 is arranged in a strip shape in the middle position of the substrate 51. The first through hole 511 corresponds to the heat exchange tube 6, and the heat exchange tube 6 can pass through the substrate 51 through the first through hole 511, so as not to affect the installation of the heat exchange tube 6. The first through hole 511 includes a first enlarged portion 5111, which is circular to facilitate the flow of the phase change heat storage medium 4 on the upper and lower parts of the substrate 51. The second through hole 512 is a circular hole, and multiple second through holes 512 are arranged in a ring array on the substrate 51. In this embodiment, the ring array of second through holes 512 is provided with inner and outer rings, and the inner and outer rings of the ring array of second through holes 512 are centered on the center of the substrate 51. Multiple graphite blocks 53 are placed on the substrate 51. In this embodiment, the graphite blocks 53 are spherical and the diameter of the graphite blocks 53 is larger than the diameter of the second through hole 512. The graphite blocks 53 are placed on the second through hole 512, so that the lower part of the graphite blocks 53 is located in the second through hole 512. The second through hole 512 can position the graphite blocks 53 and prevent the graphite blocks 53 from rolling.The pressure plate 52 is located above the graphite block 53 and corresponds to the substrate 51. The pressure plate 52 is also a circular plate with a diameter corresponding to the inner diameter of the inner shell 3. The pressure plate 52 is provided with a third through hole 521 and multiple fourth through holes 522. Both the third through hole 521 and the fourth through holes 522 extend from the upper end face to the lower end face of the pressure plate 52. The third through hole 521 corresponds to the first through hole 511. The third through hole 521 is also strip-shaped and located in the middle of the pressure plate 52. The heat exchange tube 6 can pass through the pressure plate 52 through the third through hole 521 without affecting the installation of the heat exchange tube 6. The third through hole 521 includes a second enlarged portion 5211, which is circular to facilitate the flow of the phase change heat storage medium 4 above and below the pressure plate 52. The diameter of the fourth through hole 522 is larger than the diameter of the first enlarged part 5111, but smaller than the diameter of the circle containing the multiple second through holes 512 in the inner ring, so that the pressure plate 52 can press on the multiple graphite blocks 53. The fourth through hole 522 is a circular hole, and the multiple fourth through holes 522 are distributed in a ring array on the pressure plate 52. In this embodiment, the ring array of fourth through holes 522 is provided with inner and outer rings. The inner and outer rings of the fourth through holes 522 are centered on the center of the pressure plate 52, and the diameter of the circle containing the inner and outer rings of fourth through holes 522 is different from the diameter of the circle containing the inner and outer rings of second through holes 512. Thus, the fourth through hole 522 is misaligned with the second through hole 512, and the fourth through hole 522 facilitates the flow of the phase change heat storage medium 4 above and below the pressure plate 52.

[0033] like Figure 1 , Figure 4 and Figure 5 As shown, the pressure plate 52 is provided with a second limiting block 524. Two second limiting blocks 524 are symmetrically arranged and connected to the outer circumferential sidewall of the pressure plate 52. The inner wall of the inner shell 3 is provided with a displacement groove 311, which extends downward from the top of the shell body of the inner shell 3. The width of the displacement groove 311 corresponds to the second limiting block 524. Two displacement grooves 311 are also provided. When the pressure plate 52 moves downward, the second limiting block 524 moves downward in the corresponding displacement groove 311. The inner wall of the inner shell 3 is also provided with a second limiting groove 313, which is connected to the displacement groove 311. The second limiting groove 313 extends laterally along the inner wall of the inner shell 3. The shape of the second limiting groove 313 corresponds to that of the second limiting block 524. The second limiting grooves 313 connected by the two displacement grooves 311 are arranged symmetrically along the axis. Each displacement groove 311 connects to multiple second limiting grooves 313. In this embodiment, the number of second limiting grooves 313 connected to each displacement groove 311 corresponds to the number of pressure plates 52, and three are set. The three second limiting grooves 313 are set at equal distances. When the pressure plate 52 moves downward to the position corresponding to the second limiting groove 313, the pressure plate 52 is rotated (the outer wall of the second limiting block 524 is arc-shaped to facilitate the rotation of the pressure plate 52), and the second limiting block 524 enters the corresponding second limiting groove 313, thereby completing the limiting of the pressure plate 52.

[0034] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, multiple graphite block groups 5 are provided. In this embodiment, three graphite block groups 5 are provided, which are stacked one on top of the other. The pressure plate 52 is provided with two rod grooves 523 corresponding to the support rods 54. The rod grooves 523 are circular blind holes provided on the upper end face of the pressure plate 52. The inner bottom wall of the inner shell 3 is also provided with two rod grooves 523. When the graphite block groups 5 are stacked, the support rods 54 of the bottom substrate 51 are inserted into the rod grooves 523 on the inner bottom wall of the inner shell 3, and multiple graphite blocks 53 are placed in the corresponding second through holes 512. The number of graphite blocks 53 can be selected as needed, with a maximum number corresponding to the number of second through holes 512 on the substrate 51. In this embodiment, it is 30. The second limiting block 524 of the pressure plate 52 is placed into the corresponding displacement groove 311, and the pressure plate 52 is slid down until it presses onto the graphite blocks 53. At this time, the pressure plate 52 is rotated, and the second limiting block 524 enters the corresponding second limiting groove 313, completing the limiting of the pressure plate 52. At this time, the pressure plate 52 presses onto the graphite blocks 53, completing the fixation of the graphite blocks 53. After the bottom graphite block group 5 is installed, the middle graphite block group 5 is installed. The support rod 54 of the base plate 51 of the middle graphite block group 5 is inserted into the rod groove 523 of the lower pressure plate 52. Then, multiple graphite blocks 53 are placed on the second through holes 512 of the corresponding middle base plate 51. The number of graphite blocks 53 can be selected as needed, and the maximum number can be up to the number of the second through holes 512 on the corresponding base plate 51. In this embodiment, it is 30. The second limiting block 524 of the middle pressure plate 52 is placed into the corresponding displacement groove 311. The pressure plate 52 is slid down until the middle pressure plate 52 presses onto the middle graphite blocks 53. At this time, the middle pressure plate 52 is rotated, and the second limiting block 524 of the middle pressure plate 52 enters the corresponding second limiting groove 313 to complete the limiting of the middle pressure plate 52, thereby completing the installation of the middle graphite block group 5. The installation of the upper graphite block group 5 is completed in this way. The entire graphite block assembly 5 (substrate 51, pressure plate 52, multiple graphite blocks 53, and support rods 54) is made of graphite powder through pressing and high-temperature sintering. This process resists the penetration of molten metal and increases the thermal conductivity of the phase change thermal storage medium 4. Since the number of graphite blocks 53 in each graphite block assembly 5 is selectable, different numbers of graphite blocks 53 can be placed at different positions (top, middle, bottom). Depending on the characteristics of different phase change thermal storage media 4, different numbers of graphite blocks 53 can be placed at different positions to obtain optimal thermal storage capacity and rate.During the experiment, multiple heat storage tanks were set up. The number and position of graphite blocks 53 in the three graphite block groups 5 (top, middle, and bottom) of each heat storage tank were different. Under the same external heat source and phase change heat storage medium 4, existing detection methods, such as the temperature change method, were used to monitor the temperature change of the inner shell 3 under certain conditions, determine the rate of temperature change, and calculate the overall heat storage capacity based on the temperature change curve. This allowed the overall heat storage rate and heat storage capacity of different heat storage tanks to be determined. Based on actual usage needs, the heat storage tank with a suitable heat storage capacity and heat storage rate was selected. (Increasing the number of graphite blocks 53 can improve the heat storage rate of the phase change heat storage medium 4, but excessive graphite blocks 53 will reduce the heat storage capacity of the phase change heat storage medium 4. Therefore, it is necessary to select a heat storage tank with a suitable heat storage capacity based on actual usage needs.)

[0035] Example 2

[0036] like Figure 6 , Figure 7 , Figure 8 and Figure 9As shown, the difference from Embodiment 1 is that the graphite block assembly 5 in this embodiment includes a substrate 51, a pressure plate 52, and multiple graphite blocks 53, but does not include support rods 54. Correspondingly, the pressure plate 52 and the inner bottom wall of the inner shell 3 are not provided with rod grooves 523. The substrate 51 in this embodiment is provided with two first limiting blocks 514, and the inner wall of the inner shell 3 is provided with a first limiting groove 312. The first limiting groove 312 is connected to the displacement groove 311 and corresponds to the first limiting block 514. In this embodiment, the shape and position of the first limiting block 514 correspond to the second limiting block 524, and the shape of the first limiting groove 312 corresponds to the second limiting groove 313. One first limiting groove 312 and its corresponding... A second limiting groove 313 forms a set of limiting grooves. Multiple sets of limiting grooves are connected to each displacement groove 311. These multiple sets of limiting grooves are arranged vertically, and the distance between adjacent first limiting grooves 312 and second limiting grooves 313 is equal. Therefore, the first limiting groove 312 and second limiting groove 313 are interchangeable. When the substrate 51 rotates, the first limiting block 514 of the substrate 51 can enter the corresponding height of the first limiting groove 312 or the second limiting groove 313. Thus, the substrate 51 can be positioned at different heights within the inner shell 3. Simultaneously, when the pressure plate 52 rotates, the second limiting block 524 of the pressure plate 52 can enter the corresponding height of the first limiting groove 312 or the second limiting groove 313. Therefore, the distance between adjacent graphite block groups 5 is adjustable, allowing different numbers of graphite block groups 5 to be positioned at different heights within the inner shell 3. Since the first limiting groove 312 and the second limiting groove 313 have the same shape, the substrate 51 and the pressure plate 52 can be screwed into different first limiting grooves 312 or second limiting grooves 313, so the distance between the pressure plate 52 and the substrate 51 can also be varied. A larger diameter spherical graphite block 53 can be replaced between the pressure plate 52 and the substrate 51. Spherical graphite blocks 53 with different diameters will result in heat storage tanks with different heat storage rates and heat storage capacities to meet actual use requirements. During the experiment, multiple heat storage tanks were set up. The number and position of graphite blocks 53 in multiple graphite block groups 5 in each heat storage tank were different. The distance between the pressure plate 52 and the base plate 51 could also be selected with different spacing. The graphite blocks 53 were selected as spherical blocks with corresponding diameters. Under the same external heat source and phase change heat storage medium 4, the temperature change method was used to detect the temperature change of the inner shell 3 under certain conditions, to grasp the temperature change rate, and to calculate the overall heat storage capacity based on the temperature change curve. In this way, the overall heat storage rate and heat storage capacity of different heat storage tanks could be grasped. According to the actual use needs, the heat storage tank with a suitable heat storage capacity and heat storage rate could be selected.

[0037] like Figure 6 As shown, the difference from Embodiment 1 is that the heat exchange section 63 in this embodiment is a serpentine tube, which can extend the length of the heat exchange section and the heat exchange time of the external heat source, thereby improving the heat exchange effect. The phase change heat storage medium 4 adopts existing gallium-based alloys, bismuth-antimony alloys, or tin-based alloys.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A phase change heat storage tank having a graphite block, characterized by, The application relates to a phase change heat storage device, which comprises an outer shell (1), a heat preservation layer (2) arranged in the outer shell (1), an inner shell (3) arranged in the heat preservation layer (2), a phase change heat storage medium (4) arranged in the inner shell (3), a graphite block group (5) arranged in the phase change heat storage medium (4) and a heat exchange pipe (6) for heat exchange with the phase change heat storage medium (4), wherein the heat exchange pipe (6) comprises a heat exchange section (63) immersed in the phase change heat storage medium (4), and the graphite block group (5) comprises a base plate (51), a pressing plate (52) corresponding to the base plate (51) and a plurality of graphite blocks (53) arranged between the base plate (51) and the pressing plate (52).

2. The phase change heat storage tank with graphite blocks according to claim 1, characterized in that, The base plate (51) is provided with a first through hole (511) corresponding to the heat exchange pipe (6) and a plurality of second through holes (512) corresponding to the graphite blocks (53), and the pressing plate (52) is provided with a third through hole (521) corresponding to the heat exchange pipe (6) and a plurality of fourth through holes (522) for the flow of the phase change heat storage medium (4).

3. The phase change heat storage tank with graphite blocks according to claim 2, characterized in that, The base plate (51) is provided with a foot rod (54), and the pressing plate (52) is provided with a rod groove (523) corresponding to the foot rod (54).

4. The phase change heat storage tank with graphite blocks according to claim 1, characterized by, The pressing plate (52) is provided with a second limiting block (524), the inner wall of the inner shell (3) is provided with a displacement groove (311) corresponding to the second limiting block (524), and the inner wall of the inner shell (3) is provided with a second limiting groove (313) connected with the displacement groove (311) and corresponding to the second limiting block (524).

5. The phase change heat storage tank with graphite blocks according to claim 4, characterized in that, The base plate (51) is provided with a first limiting block (514), and the inner wall of the inner shell (3) is provided with a first limiting groove (312) connected with the displacement groove (311) and corresponding to the first limiting block (514).

6. The phase change heat storage tank with graphite blocks according to claim 1, characterized by, The graphite block group (5) is provided in a plurality of groups, and the plurality of graphite block groups (5) are arranged in an up-down interval.

7. The phase change heat storage tank with graphite blocks according to claim 2, characterized by, The plurality of second through holes (512) are arranged in a ring array on the base plate (51), and the plurality of fourth through holes (522) are arranged in a ring array on the pressing plate (52).

8. The phase change heat storage tank with graphite blocks according to claim 2, characterized by, The first through hole (511) comprises a first enlarged portion (5111), the third through hole (521) comprises a second enlarged portion (5211), and the first and second enlarged portions (5111) and (5211) are circular.

9. The phase change heat storage tank with graphite blocks according to claim 1, characterized by, The inner shell (3) is made of graphite material.

10. The phase change heat storage tank with graphite blocks according to claim 2, characterized by, The phase change heat storage medium (4) is a metal phase change material or an organic phase change material.

Images