Instantaneous high-efficiency heat storage type phase change heat exchanger

Abstract

The application discloses a kind of transient high-efficiency heat storage phase change heat exchanger, first propose that micro channel heat exchange pipe and the manifold connection of inside and outside side manifold are formed into arc heat exchanger module.Heat exchange module is connected with inside and outside side current collector ring, and is evenly distributed on inside and outside side current collector ring by annular array heat exchange module, forms a circular drum heat exchanger structure.The transient high-efficiency heat storage phase change heat exchanger utilizes micro channel heat exchange pipe and arc heat exchange module structure, so that fluid in pipe generates secondary circulation, increases the heat exchange capacity of heat exchange module;While the arc heat exchange module structure realizes more micro channel heat exchange pipe in limited heat exchange space, increases the effective heat exchange area of heat exchanger.Using the phase change heat storage phase change heat exchanger can realize 4120J per second heat storage, solves the problem of huge heat transient storage and dispersion of high-power equipment.

Description

Technical Field

[0001] This invention belongs to the field of phase change heat exchange technology, specifically relating to an instantaneously efficient heat storage phase change heat exchanger. Background Technology

[0002] A thermal storage phase change heat exchanger refers to a heat exchanger in which a solid phase change material is filled around the heat exchange tube. When the high-temperature heat exchange medium flows through the heat exchanger structure, it transfers heat to the phase change material. After absorbing the heat, the phase change material melts into a liquid state. During the melting process, the phase change material absorbs a large amount of heat generated by the system, thereby achieving the purpose of instantaneous and efficient heat storage.

[0003] With the increasing heat dissipation of missile-borne, spaceborne, and laser-based equipment, the storage and dissipation of the massive amounts of heat generated instantaneously has become a pressing issue. Thermal storage phase change heat exchangers are currently the most effective means of storing the instantaneous ultra-high power heat generated by missile-borne, spaceborne, and laser weapons. For missile-borne equipment, when the equipment is powered on, the large amount of heat generated in a short period is stored in the phase change material through a high-efficiency phase change heat exchanger to ensure the safe operation of the phased array radar power amplifier chip within its allowable temperature range. After destroying the enemy target, the phase change heat exchanger completes its mission. For spaceborne or laser-based equipment, which operates in a pulsed mode, the heat generated during operation is transferred to the phase change material through a high-efficiency phase change heat exchanger. During non-operational periods, the heat in the phase change material is dissipated through radiant radiators or cooling systems, thus ensuring the normal operation of the spaceborne or laser-based equipment within its allowable temperature range.

[0004] To prevent leakage after the phase change material melts, most current phase change heat exchangers use shell-and-tube heat exchangers. Their structure generally includes: heat exchange tubes, a sealed shell, inlet and outlet manifolds, and inlet and outlet piping. The high-temperature heat exchange medium enters the inlet manifold from the liquid inlet, then flows through the heat exchange tubes. The phase change material comes into full contact with the heat exchange tubes, completing the heat exchange process. The cooled heat exchange medium collects in the outlet manifold and then flows out of the heat exchanger. The phase change material, through a phase change, utilizes its latent heat to remove the heat from the heat exchange medium.

[0005] Current phase change heat exchangers mostly use straight tubes, arranged in either co-current or cross-current flow. The inventors discovered that this traditional straight-tube co-current or cross-current arrangement limits the number of heat exchange tubes that can be accommodated within a limited heat exchange space, resulting in a small actual heat exchange area. This leads to larger heat exchange volumes, higher weight, and poorer performance in phase change thermal storage cooling systems, thus affecting the heat storage efficiency. Facing the increasingly urgent heat storage and dissipation needs of missile-borne, spaceborne, and other weapon platforms, there is a pressing need for a small, lightweight, and highly efficient instantaneous thermal storage phase change heat exchanger. Summary of the Invention

[0006] This invention proposes a heat storage phase change heat exchanger with instantaneous high efficiency (4120J of heat storage within 1 second). By providing a novel structure and arrangement of the heat exchange tubes in the main body of the heat exchanger, the heat exchange area under the same heat exchange space is increased, so that the phase change material and the heat exchange tubes can be in full contact, thereby effectively improving the heat exchange capacity of the phase change heat exchanger and reducing the volume and weight of the heat exchanger.

[0007] The technical solution for achieving this invention is as follows: a high-efficiency, instantaneous heat storage phase change heat exchanger capable of storing 4120J of heat within 1 second, comprising a heat exchanger shell, two liquid inlets, two liquid outlets, and an outer collector ring, an outer support ring, an inner collector ring, an inner support ring, and several heat exchange modules disposed within the heat exchanger shell; the inner support rings are concentrically and coplanarly disposed within the outer support rings, and the inner collector rings are concentrically and coplanarly disposed within the outer collector rings, with the inner support rings located directly above the inner collector rings and the outer support rings located directly above the outer collector rings; the several heat exchange modules are evenly distributed in a ring array to connect the inner collector rings and the outer collector rings, and the cavity formed between two adjacent heat exchange modules is used to fill the phase change material, so that the heat exchange modules, the inner collector rings, and the outer collector rings combine to form a drum-shaped radiator structure; the two liquid inlets are located at the bottom of the outer collector rings and extend out of the heat exchanger shell, and the two liquid outlets are located at the bottom of the inner collector rings and extend out of the heat exchanger shell.

[0008] Each heat exchange module includes an outer manifold, an inner manifold, and several microchannel heat exchange tubes. The microchannel heat exchange tubes are bent at a certain angle to form an arc structure to connect the outer manifold and the inner manifold. The inner and outer manifolds are connected through the outer and inner manifolds on several heat exchange modules, with the inner manifold connected to the inner manifold and the outer manifold connected to the outer manifold.

[0009] The hot heat exchange medium enters the outer manifold through the inlet and is evenly distributed into the microchannel heat exchange tubes of each heat exchange module via the outer manifold. The heat exchange medium flows from the outside of the heat exchanger to the inside of the heat exchanger along the microchannel heat exchange tubes, and finally merges into the inner manifold through the inner manifold, completing one heat exchange cycle. During the flow of the heat exchange medium from the outer manifold to the inner manifold, the phase change material located between the two heat exchange modules can fully contact the microchannel heat exchange tubes of the heat exchange module. The phase change material absorbs heat, accelerating the change of the phase change material from solid to liquid, achieving the purpose of efficient heat storage in the heat storage phase change heat exchanger. On the other hand, because the microchannel heat exchange tubes are arc-shaped, they can increase the turbulence of the fluid in the microchannels, causing the fluid in the microchannel heat exchange tubes to form a secondary circulation during the flow process, increasing the heat exchange capacity of the working medium in the microchannel heat exchange tubes. This also improves the heat exchange capacity of the heat exchanger and helps to accelerate the liquefaction of the solid phase change material.

[0010] Compared with the prior art, the significant advantages of this invention are:

[0011] (1) An arc-shaped micro-channel manifold heat exchange module was used. Under certain heat exchanger volume constraints, more heat exchange tubes can be arranged inside the heat exchanger, which greatly improves the specific surface area of ​​the heat exchanger and increases the contact area between the heat exchanger and the phase change material, thereby enhancing the heat exchange capacity of the high-efficiency heat exchanger.

[0012] (2) The microchannel heat exchange tubes of the heat exchange module are bent at a certain angle to become arc-shaped. On the one hand, the flow direction of the hot fluid changes continuously during the flow process, increasing the secondary circulation inside the tube, disturbing the boundary layer inside the tube, and increasing the convective heat transfer coefficient of the fluid inside the tube. On the other hand, the bending of the heat exchange module at a certain angle allows the length of the heat exchange tube to be moderately increased under the same inner and outer collector ring spacing, thereby prolonging the contact time between the hot fluid and the phase change material, and further increasing the heat exchange capacity of the high-efficiency heat exchanger.

[0013] (3) Adding fins to the outside of the heat exchange module tube increases the heat exchange area of ​​the heat exchanger on the one hand, and the fin structure increases the strength and rigidity of the heat exchange module on the other hand, thus extending the life and reliability of the phase change high-efficiency heat exchanger. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a segmented design.

[0015] Figure 2 This is a schematic diagram of the external outline of a high-efficiency thermal storage phase change heat exchanger according to a specific embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the overall structure of the heat exchange module of the instantaneous high-efficiency thermal storage phase change heat exchanger, a specific embodiment of the present invention.

[0017] Figure 4 This is an axonometric view of the overall structure of the heat exchange module of the instantaneous high-efficiency thermal storage phase change heat exchanger, a specific embodiment of the present invention.

[0018] Figure 5 This is a bottom view of the overall structure of the heat exchange module of the instantaneous high-efficiency thermal storage phase change heat exchanger, which is a specific embodiment of the present invention.

[0019] Figure 6 This is a schematic diagram of a heat exchange module of a high-efficiency, instantaneous thermal storage phase change heat exchanger, which is a specific implementation of the present invention.

[0020] Figure 7 This is a partial enlarged view of point A of the instantaneous high-efficiency thermal storage phase change heat exchanger, a specific embodiment of the present invention.

[0021] Figure 8 This is a partial enlarged view of the manifold of a high-efficiency, instantaneous thermal storage phase change heat exchanger, a specific embodiment of the present invention.

[0022] Figure 9 This is a schematic diagram of the bending angle of the heat exchange module of the instantaneous and efficient thermal storage phase change heat exchanger, which is a specific embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0025] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly and specifically defined.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; "connection" can mean a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible to those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0028] The following section will further introduce the specific implementation method, as well as the technical difficulties and inventive points of this invention, using this design example as an example.

[0029] A high-efficiency (4120J heat storage within 1 second) thermal storage phase change heat exchanger includes a heat exchanger shell 3, two liquid inlets 2, two liquid outlets 1, and an outer collector ring 4, an outer support ring 7, an inner collector ring 8, an inner support ring 9, and several heat exchange modules disposed within the heat exchanger shell 3. The inner support ring 9 is concentrically and coplanarly disposed within the outer support ring 7, and the inner collector ring 8 is concentrically and coplanarly disposed within the outer collector ring 4, with the inner support ring 9 located directly above the inner collector ring 8 and the outer support ring 7 located directly above the outer collector ring 4. Several heat exchange modules are evenly distributed in a ring array to connect the inner collector ring 8 and the outer collector ring 4. The cavity formed between two adjacent heat exchange modules is filled with phase change material, so that the heat exchange modules, the inner collector ring 8, and the outer collector ring 4 combine to form a drum-shaped radiator structure. Two liquid inlets 2 are located at the bottom of the outer manifold 4 and extend out of the heat exchanger housing 3, and two liquid outlets 1 are located at the bottom of the inner manifold 8 and extend out of the heat exchanger housing 3.

[0030] Each heat exchange module includes an outer manifold 6, an inner manifold 10, and several microchannel heat exchange tubes 5. The microchannel heat exchange tubes 5 are bent at a certain angle to form an arc-shaped structure to connect the outer manifold 6 and the inner manifold 10. The inner manifold ring 8 and the outer manifold ring 4 are connected through the outer manifold 6 and the inner manifold 10 on several heat exchange modules, wherein the inner manifold 10 is connected to the inner manifold ring 8, and the outer manifold 6 is connected to the outer manifold ring 4.

[0031] In the instantaneous high-efficiency thermal storage heat exchanger of this invention, the hot heat exchange medium enters the outer manifold 4 through the inlet 2, and is evenly distributed into the microchannel heat exchange tubes 5 of each heat exchange module via the outer manifold 6. The heat exchange medium flows from the outside of the heat exchanger to the inside of the heat exchanger along the microchannel heat exchange tubes 5, and finally converges into the inner manifold 8 via the inner manifold 10, completing one heat exchange cycle. During the process of the heat exchange medium flowing from the outer manifold 4 to the inner manifold 8, the phase change material located between the two heat exchange modules can fully contact the microchannel heat exchange tubes 5 of the heat exchange modules. The phase change material absorbs heat, accelerating the change of the phase change material from solid to liquid, thus achieving the purpose of high-efficiency thermal storage in the thermal storage phase change heat exchanger. On the other hand, since the microchannel heat exchange tube 5 is arc-shaped, it can increase the turbulence of the fluid in the microchannel, so that the fluid in the microchannel heat exchange tube 5 forms a secondary circulation during the flow process, which increases the heat exchange capacity of the working fluid in the microchannel heat exchange tube 5. This also improves the heat exchange capacity of the heat exchanger and helps the solid phase change material to liquefy faster.

[0032] During the heat exchange process, the physical properties of the heat exchange medium are constantly changing. To obtain accurate design results, the heat exchange module of this instantaneously efficient thermal storage phase change heat exchanger adopts a segmented design method. The principle of segmented design is as follows: Figure 1As shown, in the design process of the heat exchange module of a high-efficiency thermal energy storage phase change heat exchanger, the inlet temperature of the hot fluid, the phase change temperature of the phase change material, and the latent heat of fusion of the phase change material are generally known. Since the heat gained by the phase change material is equal to the heat released by the hot fluid, we can calculate the heat Q transferred by a single heat exchange module during the heat exchange process. At this point, we can divide a single heat exchange module of the high-efficiency thermal energy storage phase change heat exchanger into N equal segments. Since the heat exchange capacity of each segment is equal, we can consider each segment of the heat exchange module as a miniature independent heat exchanger. For the i-th independent heat exchanger segment, its heat exchange capacity is known. The inlet temperature of the hot fluid is T h,i-1 The specific heat capacity of the heat fluid is c. ph,i The phase change material has a phase change temperature of T0 and a latent heat of fusion of r. Since the independent heat exchanger is considered a miniature heat exchanger, it is assumed that there is no heat loss during the heat exchange process. Therefore, the heat released by the hot fluid will necessarily be completely absorbed by the phase change material. Based on this, the outlet temperature T of the i-th segment of the independent heat exchanger is calculated using the heat balance equation. h,i :

[0033]

[0034] Where, m h Let m be the mass flow rate of the heat fluid in the i-th independent heat exchanger segment. c Let T be the mass of the phase change material in the i-th independent heat exchanger. Since the independent heat exchanger is considered as a micro heat exchanger, and the heat exchange medium is under high pressure during the heat exchange process, the friction loss is small, less than 0.1% of the inlet pressure. Therefore, the pressure of the hot fluid in the independent heat exchanger can be considered constant. During the heat exchange process, the physical properties of the hot fluid can be regarded as a single-valued function of temperature. Using data from the NIST database, a piecewise polynomial expression for the specific heat capacity of the hot fluid as a function of temperature is fitted. Using the obtained specific heat of the hot fluid, the outlet temperature T of the hot fluid in the i-th independent heat exchanger is obtained according to equation (1). h,i Next, we will use equations (2) and (3) to calculate the logarithmic mean temperature difference ΔT of the independent heat exchanger. i and qualitative temperature T i,ave :

[0035]

[0036] T i,ave =0.5(T) h,i-1 +T h,i (3)

[0037] Based on the heat transfer coefficient k of each individual heat exchanger i Heat exchange Q i And the corresponding heat exchange area Ai By using the function summation method, the heat transfer areas of each independent heat exchanger are added together to obtain the total heat transfer area A of a single heat exchange module. i As shown in equation (4): the total heat exchange area A of the m heat exchange modules of the entire heat exchanger can then be calculated, as shown in equation (5):

[0038]

[0039] A = mA i (5)

[0040] In the formula, m is the number of heat exchange modules in the high-efficiency thermal energy storage phase change heat exchanger, N is the number of segments in a single heat exchange module, A is the total heat exchange area of ​​the heat exchanger, Q is the heat exchange capacity of each heat exchange module, and ΔT is the heat exchange capacity of each heat exchange module. i Logarithmic mean temperature difference for each individual heat exchanger, k i The heat transfer coefficient for each individual heat exchanger. To calculate the total heat transfer area A, we also need to know the heat transfer coefficient k of each individual heat exchanger. i :

[0041]

[0042] In the formula, δ is the wall thickness of the microchannel heat exchange tube 5, and λ w This refers to the thermal conductivity of the microchannel heat exchanger tube 5, the value of which can be obtained from the material handbook. h,i The surface convective heat transfer coefficient of the hot fluid channel in an independent heat exchanger is closely related to the structure of the heat exchanger. Factors affecting its magnitude include the flow velocity u of the hot fluid, the density ρ of the hot fluid, and the thermal conductivity λ of the hot fluid. f The dynamic viscosity η of the thermal fluid and the specific heat capacity c of the thermal fluid. p The diameter d of the microchannel heat exchange tube 5, the length l of the microchannel heat exchange tube 5, and the bending angle θ of the heat exchange module.

[0043] h h,i =f(u,ρ,λ) f ,η,c p ,d,l,θ) (7)

[0044] To obtain the correspondence between the convective heat transfer coefficient of the heat exchange module and the structure of the heat exchanger in a high-efficiency, instantaneous thermal storage phase change heat exchanger, it is necessary to describe the heat transfer process of the microchannel heat exchange tube 5 using mathematical equations, thereby obtaining the corresponding relationships. The complete mathematical model includes the continuity equation, the momentum conservation equation, and the energy conservation equation, with specific expressions as follows:

[0045]

[0046]

[0047]

[0048] In the formula, u x u y u z Let be the velocities of the thermal fluid in the x, y, and z directions, respectively; ρ be the density of the thermal fluid; p be the infinitesimal pressure of the thermal fluid; μ be the kinematic viscosity of the thermal fluid; H be the enthalpy of the thermal fluid; and λ be the velocity of the thermal fluid in the x, y, and z directions, respectively. f is the thermal conductivity of the hot fluid.

[0049] Using numerical calculation methods, equations (7) to (9) are discretized. A genetic algorithm is used to iteratively optimize the pipe diameter, pipe length, and bending angle of the heat exchange module of the microchannel heat exchange tube 5. Finally, the relationship between the convective heat transfer coefficient and structural parameters of the instantaneously efficient thermal storage phase change heat exchanger is obtained as follows:

[0050]

[0051] In the formula: Re f Pr is the Reynolds number of the thermal fluid. f For the Prandtl number of the thermal fluid, Pr w λ is the Prandtl number of the thermofluid at the phase change temperature. f denoted as the thermal conductivity of the hot fluid, d as the diameter of the microchannel heat exchange tube 5, l as the length of the microchannel heat exchange tube 5, and θ as the bending angle of the heat exchange module.

[0052] The formula for the total heat exchange of the instantaneously efficient thermal storage phase change heat exchanger can be obtained as follows:

[0053] Q 总 =m·Q (12)

[0054] In the formula: m is the number of heat exchange modules, and Q is the heat transferred by a single heat exchange module.

[0055] Preferably, the outer manifold 6 of each heat exchange module is vertically connected to the outer manifold 4, and the inner manifold 10 is vertically connected to the inner manifold 8. The heat exchange module is bent at a certain angle to form an arc-shaped structure. Several heat exchange modules are evenly arranged on the entire circumference to form an instantaneously efficient heat storage phase change heat exchanger. The microchannel heat exchange tubes 5 of the heat exchange module are arranged at an angle from the outer manifold 4 to the inner manifold 8, which allows more microchannel heat exchange tubes 5 to be arranged in the same volume space, making full use of the heat exchanger's volume space, increasing the ratio of the heat exchanger's surface area to its volume, and increasing the effective heat exchange area.

[0056] Preferably, the bending angle θ of each heat exchange module is [60°, 120°]. The bending angle of the heat exchange module helps to increase the convective heat transfer coefficient of the hot fluid within the microchannel heat exchange tube 5. When the hot fluid flows through the heat exchange module, due to the bending effect of the microchannel, the radius of the circular motion of the hot fluid gradually decreases as it moves from the outer manifold 6 to the inner manifold 10 of the heat exchange module. Simultaneously, the flow direction of the fluid is constantly changing. Under the action of centrifugal force, the hot fluid forms a secondary circulation within the tube. The existence of this secondary circulation disrupts the original boundary layer, increasing the convective heat transfer coefficient. Furthermore, compared to a straight microchannel, bending the microchannel heat exchange tube 5 allows the fluid to travel a greater distance at the same displacement, providing more time for heat exchange with the phase change material, which further enhances the heat exchanger's heat transfer capacity.

[0057] Preferably, when the outer manifold ring 4 of the heat exchanger is limited to 500mm, the number of heat exchange modules m is selected as 20-25. Too many heat exchange modules will result in overly dense heat exchange tube rows, with insufficient phase change material to fill the spaces between the modules, which is insufficient to remove the heat from the fluid inside the microchannel heat exchange tubes 5, thus reducing the heat exchange capacity of the high-efficiency heat exchanger. Too few heat exchange modules will result in excessively large exposed spaces between the tube rows, insufficient heat exchange area, and some phase change material will not be able to contact the microchannel heat exchange tubes 5, causing a decrease in the heat exchanger's heat exchange capacity.

[0058] Preferably, each heat exchange module has 60-80 microchannel heat exchange tubes 5. Too many microchannel heat exchange tubes 5 in each module increase the frictional resistance of the heat flow from the outer manifold 6 to the inner manifold 10, leading to uneven heat flow distribution within the microchannel heat exchange tubes 5. This may result in some microchannel heat exchange tubes having no heat flow, causing uneven heat exchange capacity at different locations within the heat exchanger and reducing the overall heat exchange capacity. Furthermore, too many microchannel heat exchange tubes 5 in each module increase the manifold diameter, resulting in a larger overall volume of the high-efficiency heat exchanger. Conversely, too few heat exchange tubes reduce the actual heat exchange area, preventing sufficient contact between the heat flow and the phase change material, thus reducing the heat exchange capacity of the high-efficiency heat exchanger.

[0059] Ideally, the diameter d of the microchannel heat exchanger tube 5 in each module should be 0.5mm-3mm. With the same high-efficiency heat exchanger volume, selecting microchannel heat exchanger tubes increases the number of microchannel heat exchanger tubes 5 in the heat exchanger, increasing the overall heat exchange area and indirectly increasing the heat exchanger's heat exchange capacity. Simultaneously, the fluid boundary layer is thinner in the microchannel heat exchanger tubes 5, resulting in stronger heat exchange capacity. Therefore, selecting microchannel heat exchanger tubes 5 can enhance the heat exchange performance of the high-efficiency heat exchanger. Selecting large-channel heat exchanger tubes would result in insufficient utilization of the heat exchanger's volume. Furthermore, large-channel heat exchanger tubes would increase the diameter of the heat exchanger's manifold, leading to an increase in the diameter of the manifold and ultimately a larger overall size of the heat exchanger.

[0060] The preferred heat exchanger has two inlets and two outlets. Since a single arc-shaped heat exchanger module contains hundreds of micro-channel heat exchange tubes connected in parallel, and the entire module has 20-25 identical heat exchange modules, two inlets and two outlets can be arranged on the manifold to further reduce fluid flow resistance. With two inlets and two outlets, the flow velocity of the hot fluid entering the manifold decreases, reducing frictional resistance within the manifold and lowering local resistance at the manifold. Furthermore, having two inlets and outlets, each corresponding to half of the heat exchange modules, ensures more uniform fluid distribution in each manifold, enhancing the heat exchange capacity of the high-efficiency heat exchanger. While more inlets and outlets are beneficial for uniform fluid distribution within the heat exchanger manifold, excessive inlet and outlet arrangement complicates the piping connections, hindering practical application.

[0061] Preferably, when the outer manifold ring 4 of the heat exchanger is limited to 500mm, the length l of a single microchannel heat exchange tube 5 in the heat exchange module is 200mm-400mm. If the length of the microchannel heat exchange tube 5 is too long, it will increase the frictional resistance during the flow of the hot fluid, resulting in a larger pump size, which is detrimental to reducing the weight of the instantaneously efficient heat storage phase change heat exchanger. It will also hinder the arrangement of the heat exchange modules inside the heat exchanger, leading to mutual interference between modules and uneven distribution of the phase change material, affecting the performance of the high-efficiency heat exchanger. If the length of the microchannel heat exchange tube 5 is too short, the volume space of the heat exchanger cannot be fully utilized. Within a given volume, the heat exchange area of ​​the heat exchanger is insufficient, resulting in insufficient heat absorption by the phase change material and failing to fully utilize the advantage of the large heat exchange surface area of ​​the high-efficiency heat exchanger.

[0062] The outer wall of the preferred microchannel heat exchange tube 5 can also be finned. The fins can be rectangular, rhomboid, or cylindrical. Adding fins increases the contact area between the high-efficiency heat exchanger and the phase change material, thereby increasing the heat exchange capacity. Furthermore, adding fins increases the structural strength of individual heat exchange modules, preventing deformation and extending the service life of the heat exchanger.

[0063] The diameter of the preferred manifold (i.e., the inner manifold 10 and the outer manifold 6) should be 4-5 times the diameter of the microchannel heat exchange tube 5. This allows the hot fluid to flow smoothly into and out of the manifold, reducing local resistance losses caused by excessive local velocity changes, and also facilitates the uniform distribution of the heat exchange medium in each microchannel heat exchange tube 5.

[0064] Furthermore, since each heat exchange module is identical and they are connected in parallel, they offer good maintainability. When some of the microchannel heat exchange tubes 5 inside the heat exchanger become blocked, the overall heat exchange capacity of the heat exchanger decreases only slightly, which helps extend the service life of the high-efficiency energy storage phase change heat exchanger.

[0065] By adopting the above technical solution and using the microchannel arc manifold heat exchange module, the space of the heat exchanger can be fully utilized, and as many heat exchange tubes as possible can be arranged in a limited space. This increases the contact area between the heat exchanger and the phase change material, thereby increasing the heat exchange capacity of the instantaneously efficient heat storage phase change heat exchanger and reducing the volume and weight of the phase change heat exchanger.

[0066] Example:

[0067] like Figures 2-9As shown, a high-efficiency, instantaneous heat storage phase change heat exchanger includes two liquid outlets 1, two liquid inlets 2, a heat exchanger shell 3, an outer manifold 4 located on the lower side of the heat exchanger, several microchannel heat exchange tubes of heat exchange modules 5, several outer manifolds of heat exchange modules 6, an outer support ring 7 located on the upper side of the heat exchanger, an inner manifold 8 located on the lower side of the heat exchanger, an inner support ring 9 located on the upper side of the heat exchanger, and several inner manifolds of heat exchange modules 10. A cavity for placing phase change material is formed between any two adjacent heat exchange modules. After the phase change material is heated and melted, it fills the cavity of the high-efficiency phase change heat exchanger. After cooling, the shell of the heat exchanger is sealed. In this implementation, the outer manifold ring 4 has a diameter of 500 mm, the inner manifold ring 8 has a diameter of 150 mm, the microchannel heat exchange tube 5 has a diameter of 1 mm and a length of 250 mm, the manifold diameter is 5 mm, the number of microchannel heat exchange tubes 5 in a single heat exchange module is 70, the bending angle of the heat exchange module is 86°, and the number of heat exchange modules is 24. The microchannel heat exchange modules are arranged in a circular array, with phase change material filling the spaces between adjacent heat exchange modules. The maximum instantaneous heat storage capacity of this phase change heat exchanger is 4120 J.

Claims

1. A design method for a high-efficiency, instantaneous thermal storage phase change heat exchanger, characterized in that: It includes a heat exchanger shell (3), two liquid inlets (2), two liquid outlets (1), and an outer collector ring (4), an outer support ring (7), an inner collector ring (8), an inner support ring (9), and several heat exchange modules disposed inside the heat exchanger shell (3); the inner support ring (9) is concentrically and coplanarly disposed inside the outer support ring (7), the inner collector ring (8) is concentrically and coplanarly disposed inside the outer collector ring (4), and the inner support ring (9) is located directly above the inner collector ring (8), and the outer support ring (7) is located directly above the outer collector ring (4); Several heat exchange modules are evenly distributed in a ring array to connect the inner collector ring (8) and the outer collector ring (4). The cavity formed between two adjacent heat exchange modules is used to fill the phase change material, so that the heat exchange modules, the inner collector ring (8), and the outer collector ring (4) are combined to form a drum-shaped radiator structure. Two liquid inlets (2) are located at the bottom of the outer collector ring (4) and extend out of the heat exchanger shell (3), and two liquid outlets (1) are located at the bottom of the inner collector ring (8) and extend out of the heat exchanger shell (3). During the heat exchange process, the physical properties of the heat exchange medium are constantly changing. In order to obtain accurate design results, the heat exchange module of this instantaneous high-efficiency thermal storage phase change heat exchanger adopts a segmented design method. In the design process of the heat exchange module of the high-efficiency thermal storage phase change heat exchanger, the inlet temperature of the hot fluid, the phase change temperature of the phase change material, and the latent heat of fusion of the phase change material are known. Since the heat gained by the phase change material is equal to the heat released by the hot fluid, the heat Q transferred by a single heat exchange module during the heat exchange process can be calculated accordingly. The single heat exchange module of the high-efficiency thermal storage phase change heat exchanger is divided into N equal segments. Since the heat exchange capacity of each segment is equal, each segment of the heat exchange module is regarded as a miniature independent heat exchanger. For the i-th independent heat exchanger, its heat exchange capacity is known. The inlet temperature of the hot fluid is T. h,i-1 The specific heat capacity of the hot fluid is c. ph,i The phase change material has a phase change temperature of T0 and a latent heat of fusion of r. Since the independent heat exchanger is considered a micro-heat exchanger, it is assumed that there is no heat loss during the heat exchange process. Therefore, the heat released by the hot fluid will inevitably be completely absorbed by the phase change material. Based on this, the outlet temperature T of the i-th segment of the independent heat exchanger is calculated using the heat balance equation. h,i : (1)， in, Let be the mass flow rate of the heat fluid in the i-th independent heat exchanger segment. Let be the mass of the phase change material in the i-th independent heat exchanger. Since the independent heat exchanger is considered as a micro heat exchanger and the heat exchange medium is under high pressure during the heat exchange process, the friction loss is small and less than 0.1% of the inlet pressure. Therefore, it is assumed that the pressure of the hot fluid in the independent heat exchanger remains constant. In the heat exchange process, the physical properties of the heat fluid are considered as a single-valued function of temperature. Using data from the NIST database, a piecewise polynomial expression for the specific heat capacity of the heat fluid as a function of temperature is fitted. Using the obtained specific heat of the heat fluid, the outlet temperature T of the heat fluid in the i-th independent heat exchanger is obtained according to equation (1). h,i Next, the logarithmic mean temperature difference ΔT of the independent heat exchanger is calculated using equations (2) and (3). i and qualitative temperature T i,ave : (2)， (3)， Based on the heat transfer coefficient k of each individual heat exchanger i Heat exchange Q i And the corresponding heat exchange area A i By using the function summation method, the heat transfer areas of each independent heat exchanger are added together to obtain the total heat transfer area A of a single heat exchange module. i As shown in equation (4): Then, the total heat exchange area A of the entire heat exchanger with m heat exchange modules is obtained, as shown in equation (5): (4)， (5)， In the formula, m is the number of heat exchange modules in the high-efficiency thermal energy storage phase change heat exchanger, N is the number of segments in a single heat exchange module, A is the total heat exchange area of ​​the heat exchanger, Q is the heat exchange capacity of each heat exchange module, and ΔT is the heat exchange capacity of each heat exchange module. i The logarithmic mean temperature difference for each individual heat exchanger, To calculate the total heat transfer area A, we also need to know the heat transfer coefficient of each individual heat exchanger. : (6)， In the formula, δ is the wall thickness of the microchannel heat exchange tube (5). The thermal conductivity of the microchannel heat exchange tube (5) is obtained by consulting the material handbook. h,i The surface convective heat transfer coefficient of the hot fluid channel in an independent heat exchanger is closely related to the structure of the heat exchanger, and its magnitude is influenced by factors such as the flow velocity of the hot fluid. Density of thermal fluids Thermal conductivity of hot fluids Dynamic viscosity of thermal fluids Specific heat capacity c of a hot fluid p The diameter of the microchannel heat exchange tube (5) Length of the microchannel heat exchange tube (5) Bending angle of heat exchange module ; (7)。 2. The design method for a high-efficiency, instantaneous thermal storage phase change heat exchanger according to claim 1, characterized in that: Each heat exchange module includes an outer manifold (6), an inner manifold (10), and several microchannel heat exchange tubes (5). The microchannel heat exchange tubes (5) are bent at a certain angle to form an arc structure to connect the outer manifold (6) and the inner manifold (10). The inner manifold (8) and the outer manifold (4) are connected through the outer manifold (6) and the inner manifold (10) on several heat exchange modules. The inner manifold (10) is connected to the inner manifold (8), and the outer manifold (6) is connected to the outer manifold (4). The hot heat exchange medium enters the outer manifold (4) through the inlet (2), and is evenly distributed to the microchannel heat exchange tubes (5) of each heat exchange module through the outer manifold (6). The heat exchange medium enters the inner side of the heat exchanger from the outside of the heat exchanger along the microchannel heat exchange tubes (5), and finally merges into the inner manifold (8) through the inner manifold (10) to complete one heat exchange. During the process of the heat exchange medium flowing from the outer manifold (4) through the inner manifold (8), the phase change material located between the two heat exchange modules and the heat exchange module The microchannel heat exchange tube (5) is in full contact with the phase change material, which absorbs heat and accelerates the phase change material from solid to liquid, thus achieving the purpose of efficient heat storage in the heat storage phase change heat exchanger. On the other hand, since the microchannel heat exchange tube (5) is arc-shaped, it can increase the disturbance of the fluid in the microchannel, so that the fluid in the microchannel heat exchange tube (5) forms a secondary circulation during the flow process, which increases the heat exchange capacity of the working fluid in the microchannel heat exchange tube (5), which also improves the heat exchange capacity of the heat exchanger and helps the solid phase change material to liquefy faster.

3. The design method for a high-efficiency, instantaneous thermal storage phase change heat exchanger according to claim 1, characterized in that: In order to obtain the correspondence between the convective heat transfer coefficient of the heat exchange module and the structure of the heat exchanger in an instantaneously efficient thermal storage phase change heat exchanger, it is necessary to describe the heat transfer process of the microchannel heat exchange tube (5) with mathematical equations, and then obtain the corresponding relationship. Its complete mathematical model includes the continuity equation, the momentum conservation equation and the energy conservation equation, and the specific expressions are as follows: (8)， (9)， (10)， In the formula, , , These represent the velocities of the thermal fluid in the x, y, and z directions, respectively. The density of the thermal fluid, For the pressure of the thermal fluid micro-element, The kinematic viscosity of the thermal fluid. The enthalpy of the heat fluid. is the thermal conductivity of the hot fluid; Using numerical calculation methods, equations (7) to (9) are discretized. A genetic algorithm is used to iteratively optimize the pipe diameter, pipe length, and bending angle of the heat exchange module of the microchannel heat exchange tube (5). Finally, the relationship between the convective heat transfer coefficient and structural parameters of the instantaneously efficient thermal storage phase change heat exchanger is obtained as follows: （11）， In the formula: The Reynolds number of the thermal fluid is... The Prandtl number is the temperature of the fluid. This represents the Prandtl number of the thermofluid at the phase change temperature. is the thermal conductivity of the hot fluid. The diameter of the microchannel heat exchange tube (5) is given. The length of the microchannel heat exchange tube (5) is given by the tube length. The bending angle of the heat exchange module; The formula for the total heat exchange of the instantaneously efficient thermal storage phase change heat exchanger is as follows: （12）， In the formula: Where is the number of heat exchange modules, and Q is the amount of heat transferred by a single heat exchange module.

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