A three-dimensional temperature field checking calculation method for a concentric circle bulging plate cylinder heat exchanger

Abstract

The application discloses a kind of concentric circle bulging plate cylinder heat exchanger three-dimensional temperature field checking calculation method: S1, according to structural parameters and operating parameters, the heat transfer coefficient of convection is calculated, and the total heat transfer coefficient is calculated according to the heat transfer coefficient of convection;S2, each heat exchange plate is divided into M Mesh, each mesh includes the inboard of the plate of the first i Circle, plate outer inside and plate outer outside, i =1,2,… N , each mesh is three flow heat exchange microelement, according to total heat transfer coefficient, the inside heat transfer coefficient of each three flow heat exchange microelement, outside heat transfer coefficient is calculated;S3, according to inside heat transfer coefficient and outside heat transfer coefficient, the first, second fluid outlet temperature value of each three flow heat exchange microelement of the first i Circle is calculated;Repeat S3 until i = N ;S4, the first, second average value of N Is calculated;S5, S3-S4 is executed until two first average values are less than preset deviation threshold, and three-dimensional temperature field calculation value is recorded.

Description

Technical Field

[0001] This invention relates to a three-dimensional temperature field verification calculation method for a concentric circular bulging plate cylindrical heat exchanger, belonging to the field of heat exchanger technology. Background Technology

[0002] With the continuous expansion of heat exchanger applications, the industry has developed heat exchanger technologies specifically for non-clean working media, such as petrochemicals, textiles, industrial wastewater containing solid particles, and sewage / sludge containing biomass. A typical product is ZL 202510168793.6, "A Three-Dimensional Variable Space Expansion Heat Exchanger and an Equal Flow Path Closed Heat Exchanger," where the outside of the plates contains the non-clean working media and the inside contains the clean working media. By combining specific half-turns between the flow channels and the number of turns on the clean working media side, "equal flow paths" are achieved on both sides, thus achieving the best overall heat exchange effect.

[0003] In existing technologies, when calculating the heat transfer performance of heat exchangers with non-clean working fluids, calculations are mainly based on one-dimensional heat exchanger design theory. For example, the thermodynamic design or verification calculation of the heat exchanger is performed using the logarithmic mean temperature difference method or the number of heat transfer units method. In this case, the multi-layer, multi-flow-path structure inside the plate is usually simplified to a single average flow path. For the flow inside and outside the tube, the classical heat transfer criterion is usually used to calculate the convective heat transfer coefficient, and the fouling thermal resistance is introduced to correct the influence of surface fouling on heat transfer. Some studies have used segmented micro-elements to analyze the temperature and pressure distribution in heat exchangers. Within each micro-element, the heat exchanger is considered as a basic unit for heat exchange between two streams of hot and cold fluids, with the overall flow arranged in counter-current. However, the purpose of this type of micro-element division is to address the problem of variable properties of the fluids at the inlet and outlet due to drastic changes in physical properties (such as fluid phase change or crossing the critical region), in order to correct the temperature difference during heat exchange. For heat exchangers with non-clean working fluids, the physical properties of the fluids on both sides remain basically unchanged during the flow process, and there is no actual need to divide the heat exchanger into micro-elements due to variable physical properties.

[0004] However, the above methods have significant shortcomings in the verification calculations for concentric circular bulging plate heat exchangers with equal flow paths. When using the logarithmic mean temperature difference method or the number of heat transfer units method, the multiple flow paths are simplified into a single average flow path, making it impossible to accurately verify the temperature distribution at the outlet of each branch and to verify the distribution effect of the equal flow path design. When using the classical heat transfer criterion and fouling thermal resistance correction, the influence of the special structure of the bulging plate on heat transfer and the non-uniform deposition characteristics of fouling are ignored. Even if some studies use micro-element partitioning, the basis for micro-element partitioning is only the nodes of physical property changes along the flow direction. In essence, each flow path is still simplified to an average treatment, and each micro-element segment is still based on a one-dimensional assumption. It cannot reflect the coupled heat transfer relationship formed by the three-dimensional serpentine cross-loop flow of the clean working fluid inside the plate ("first upward, then serpentine downward, and repeating after cross-loop switching") and the spiral upward flow of the non-clean working fluid outside the plate. It also ignores the influence of the temperature gradient in the radial direction of the concentric cylindrical structure on the overall heat transfer performance. Summary of the Invention

[0005] This invention provides a method for calculating and verifying the three-dimensional temperature field of a concentric circular bulging plate cylindrical heat exchanger, wherein the concentric circular bulging plate heat exchanger includes... N A concentric circle of expanding heat exchange plates, N The aforementioned expanding heat exchange plates are sequentially arranged radially from the inside to the outside. The working fluid inside the expanding heat exchange plates is a first fluid, and the working fluid outside the expanding heat exchange plates is a second fluid. The method includes: S1. Based on the structural and operating parameters of the concentric circular expansion plate heat exchanger, calculate the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid, and calculate the total heat transfer coefficient based on the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid. S2, Divide each of the aforementioned expanded heat exchange plates into... M There are grids, each grid including the inner side of the i-th ring plate, the ... i The outer and inner sides of the ring plate and the first i outer and outer sides of the ring plate i =1,2,…, N Each grid is called a three-stream heat transfer element; based on the total heat transfer coefficient, the inner heat transfer coefficient of each three-stream heat transfer element from the inside of the plate to the outside of the plate, and the outer heat transfer coefficient of each three-stream heat transfer element from the inside of the plate to the outside of the plate are calculated. S3. Based on the inner heat transfer coefficient and the outer heat transfer coefficient, first along the first... i The two second fluid streams, one on the inner side and the other on the outer side of the concentric circular bulging plate heat exchanger, flow spirally from the bottom inlet to the top outlet of the heat exchanger. Calculate the direction of the second fluid flow. i Circle the outlet temperature values ​​of the two second fluids of each of the three-stream heat exchange micro-elements; then follow the first fluid from the first... iFrom the right side of the centerline of the bulging heat exchange plate of the ring, from the bottom inlet of the first half of the ring to the bottom outlet of the first half of the ring, and then from the... N +1- i Calculate the flow direction of the equal flow path from the left side of the centerline of the expanded heat exchange plate of the second half of the ring, from the bottom inlet of the second half of the ring to the bottom outlet of the second half of the ring. i Circle the outlet temperature of the first fluid in each of the three-stream heat exchange micro-elements; repeat S3 until... i = N ; S4, Calculation N The first average value of the outlet temperature of the first fluid, or calculated N The second average value of the outlet temperature of the second fluid; S5. Execute steps S3-S4 until the ratio of the two first average values ​​to the second average value is less than the preset deviation threshold, and record the calculated value of the three-dimensional temperature field.

[0006] Furthermore, before calculating the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid, the following steps are also included: The total heat exchange capacity of the concentric circular bulging plate heat exchanger, the first fluid outlet temperature inside the plate, and the second fluid outlet temperature outside the plate are estimated based on the preset heat exchange effectiveness as the initial values ​​for iterative calculation.

[0007] Specifically, calculate the first i The outlet temperature of the first fluid in each of the three-stream heat exchange micro-elements is as follows: Along each i Circle the flow path direction of the second fluid and calculate the temperature field of each of the three flow heat exchange micro-elements; Along the first i Circle the flow direction of the first fluid, and calculate the sequential flow through the first... i The heat exchange zone in the first half of the circle and the first half N - i The outlet temperature of the first fluid in the second half of the heat exchange zone of +1 turn.

[0008] Specifically, along each i Determine the flow path direction of the second fluid, and calculate the temperature field of each of the three-stream heat transfer micro-elements, including: Let each i The second virtual flow circle number is s [ i ], incrementing iteration variable iter [ i ]( iter [ i ]=1,2,3,…, s [ i ]), defining the virtual process number of fluid. pass [i ]; Starting from the bottom inlet of the concentric circular expansion plate heat exchanger, the second fluid flows along... iter [ i After each concentric spiral flows through one revolution, it moves up one row until the spiral flows to... s [ i Each column flows out from the top outlet of the concentric circular bulging plate heat exchanger.

[0009] Specifically, along the first i Circle the flow direction of the first fluid, and calculate the sequential flow through the first... i The heat exchange zone in the first half of the circle and the first half N - i The outlet temperature of the first fluid in the second half of the heat exchange zone of +1 revolution includes: Define the decrementing iteration variable as iter [ j ]( iter [ j ]=1,2,3,…, s [ j ]); The first fluid begins at the bottom inlet of the concentric circular expansion plate heat exchanger, and flows along the... i The flow pattern moves vertically upwards from the first column to the top of the concentric circles, then flows downwards into the second column until it reaches the bottom outlet of the concentric circular bulging plate heat exchanger; then it enters the... N - i +1 ring of bulging heat exchange plate s [ j The water flows vertically upwards to the top of the heat exchanger plate, and then enters... s [ j The current flows downwards in column -1 until it reaches the first column, which then flows out from the bottom outlet of the concentric bulging plate heat exchanger.

[0010] According to the fluid virtual path number pass [ i The parity of the flow pattern determines the flow direction type for the first and second halves of the cycle: When the fluid virtual path number is odd, the first half-circle flow direction type ft for P1 The latter half of the flow direction type lt for P2 ; When the fluid virtual path number is even, the first half-circle flow direction type ft for P2 The latter half of the flow direction type lt for P1 .

[0011] Specifically, for each three-stream heat exchange micro-element, based on its column number... k Determine the inlet temperature of the fluid inside the plate: when k When =1, the inlet temperature is taken from the total inlet temperature or the outlet temperature of the previous row in this column; when k =2 or k When =3, the inlet temperature is taken from the outlet temperature of the next fluid virtual path number or the outlet temperature of the last line of this loop. when k When the value is 4, the inlet temperature is taken from the first column of the second pairing ring. k [ i The average outlet temperature of the row or the outlet temperature of the row above in this column; in, k [ i The number of rows contained in each virtual fluid path, determined by the number of virtual flow loops. s [ i Divide by the number of serpentine flows N flow Then round down to get the result.

[0012] Specifically, the overall heat transfer coefficient of the concentric circular bulging plate heat exchanger is calculated based on the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid.

[0013] Furthermore, while recording the calculated values ​​of the three-dimensional temperature field, the outlet temperature distribution data of each branch of the first fluid in each layer are simultaneously output to verify the uniform distribution effect of the equal flow path design.

[0014] The beneficial effects of this invention include: for the first fluid in a concentric circular expansion plate heat exchanger, employing a first... i Half circle and the first circle N - iThe +1 half-circle combined flow pattern involves the flow stream switching to the paired half-circle for heat exchange after completing the heat exchange in the first half-circle via the bottom pipe. The flow path is interrupted and reset during the circle switching. Additionally, the second fluid, while flowing vertically upwards from the bottom of the cylinder, also exhibits a spiral upward flow due to the rotation of the top motor. This invention addresses this by dividing each circle of expanded heat exchange plates into four columns and alternately performing heat transfer calculations in two directions: along the spiral flow path outside the plates and the serpentine cross-circle flow path inside the plates. This accurately reflects the coupled heat transfer relationship between the three-dimensional serpentine cross-circle flow inside the plates and the spiral upward flow outside the plates, thus solving the problem caused by the three-dimensional combined flow pattern. The present invention addresses the problem of temperature field calculation being impossible due to the different linear velocities of each ring in a concentric cylindrical structure, which leads to varying heat transfer coefficients and makes verification calculations extremely difficult. It constructs a three-flow heat transfer micro-element model consisting of a first fluid inside the plate, a second fluid on the inner side of the plate, and a second fluid on the outer side of the plate. The heat transfer coefficient and outlet temperature of each ring are calculated separately, characterizing the differences in heat transfer performance of each ring in the radial direction. Based on the parity of the fluid virtual path number, the flow direction type of the first and second halves of the ring is dynamically switched, accurately simulating the flow of the first fluid "first vertically upward along the first column, then horizontally downward in a serpentine pattern along the second column, crossing rings to the [missing information]." N - i The complex three-dimensional flow path, which involves "vertically moving upward along the fourth column after +1 revolution and then serpentine downward along the third column," enables precise verification of the outlet temperature of each branch. Through iterative calculations until the first average value obtained from the two previous cycles is less than the preset deviation threshold, the outlet temperature distribution data of each branch in each layer is output, providing a reliable three-dimensional temperature field verification basis for the optimized design of the concentric circular expansion plate heat exchanger. Attached Figure Description

[0015] Figure 1 This is a front view of a concentric circular expansion plate cylindrical heat exchanger provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the heat exchange element structure of the concentric circular expansion plate cylindrical heat exchanger provided in an embodiment of the present invention; Figure 3 This is a schematic diagram showing the unfolded heat exchange elements of the concentric circular bulging plate cylindrical heat exchanger provided in an embodiment of the present invention. Figure 4 A flowchart illustrating a three-dimensional temperature field verification calculation method for a concentric circular expansion plate heat exchanger provided in an embodiment of the present invention; Figure 5 A schematic diagram of the three-dimensional temperature field of a concentric circular bulging plate heat exchanger provided in an embodiment of the present invention, showing the three-dimensional heat transfer micro-element of the heat exchanger. Figure 6 A schematic diagram of the two-dimensional flow direction connection of the clean working fluid inside the plate provided in an embodiment of the present invention; Figure 7This is a schematic diagram of the two-dimensional flow direction connection of the non-clean working fluid outside the plate provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the three-dimensional flow direction connection of the non-clean working fluid outside the concentric circular bulging plate heat exchange micro-element plate provided in an embodiment of the present invention. Figure 9 A trend diagram showing the variation of iteration deviation with the number of iterations provided in this embodiment of the invention; In the diagram: 80, Non-clean working fluid inlet pipe and pipe box; 90a, Clean working fluid inlet pipe and pipe box; 90b, Clean working fluid outlet pipe and pipe box; 110, Outflow overflow port of the water receiving tray; 140, Motor; 150, Non-clean working fluid drain port; 160, Flat cover head; 200, Reducer; 210, Shaft; 220, Welding point; 230, Hot plate bulging thin plate; 240, Three-dimensional space of bulging inside the hot plate; 260, Support leg; 10a, First return flow inlet pipe of fluid inside the plate; 10 b. First pass outlet pipe for fluid inside the plate; 20a. Second pass inlet pipe for fluid inside the plate; 20b. Second pass outlet pipe for fluid inside the plate; 30a. First overflow port; 30b. Second overflow port; 40a. First pass exhaust port for fluid inside the plate; 40b. Second pass exhaust port for fluid inside the plate; 50. Transition port between round and flat tubes for working fluid inside the plate; 60. Top double-sided weld line of concentric hot plate element; 61. Bottom double-sided weld line of concentric hot plate element; 70. Bottom leveling hole of concentric hot plate element. Detailed Implementation

[0016] 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 some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] This invention provides a method for calculating and verifying the three-dimensional temperature field of a concentric circular bulging plate cylindrical heat exchanger. The structure of the concentric circular bulging plate cylindrical heat exchanger is as follows: Figure 1 As shown, the heat exchange element structure of the concentric circular bulging plate cylindrical heat exchanger is as follows: Figure 2 As shown, the heat exchange element structure of the concentric circular bulging plate cylindrical heat exchanger is as follows: Figure 3 As shown, based on Figure 1 , Figure 2 and Figure 3 The method for calculating the three-dimensional temperature field of the concentric circular bulging plate cylindrical heat exchanger shown is as follows: Figure 4 As shown, the method includes: S1. Based on the structural and operating parameters of the concentric circular expansion plate heat exchanger, calculate the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid, and calculate the overall heat transfer coefficient based on the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid.

[0018] Furthermore, before calculating the convective heat transfer coefficients of the first fluid and the second fluid, the method further includes: estimating the total heat transfer capacity of the concentric circular bulging plate heat exchanger, the outlet temperature of the first fluid inside the plate, and the outlet temperature of the second fluid outside the plate based on a preset heat transfer effectiveness, as initial values ​​for iterative calculation.

[0019] In this embodiment of the invention, the total heat exchange is calculated according to the energy balance formula (1), which is shown in formula (1): (1) in, Total heat exchange, in kW; For heat exchange efficiency; This is the smaller of the heat capacity flow rates on the inner and outer sides of the plate, expressed in kW / K. The inlet temperature of the second fluid is expressed in Kelvin (K). The inlet temperature of the first fluid is expressed in Kelvin (K).

[0020] Calculate the outlet temperature inside the plate and the outlet temperature outside the plate according to the temperature relationship formulas (2) and (3), respectively. (2) in, The outlet temperature of the first fluid inside the plate, in units of... k ; The mass flow rate of the first fluid is expressed in kg / s. is the isobaric specific heat capacity of the first fluid, expressed in kJ / (kg·K).

[0021] The outlet temperature on the outside of the plate is 286.75 K, calculated using the following formula: (3) in, The outlet temperature of the second fluid outside the plate, in K; The mass flow rate of the second fluid is expressed in kg / s. This is the isobaric specific heat capacity of the second fluid, expressed in kJ / (kg·K).

[0022] In this embodiment of the invention, the first fluid inside the plate is clean working fluid - water, and the inlet temperature is... T cin The inlet pressure is 281.15K. Pcin The pressure is 0.4 MPa, and the volumetric flow rate is... V cin 50m 3 / h, mass flow rate is approximately 13.9 kg / s; the second fluid outside the plate is a non-clean working fluid - domestic sewage, inlet temperature T sin The inlet pressure is 288.15K. P sin 0.1 MPa, volumetric flow rate V sin 100m 3 / h, mass flow rate is approximately 27.8 kg / s; the isobaric specific heat capacity of the first fluid is... The specific heat capacity is 4192.77 J / (kg·K), and the heat capacity flow rate is 58.3 kW / K; the isobaric specific heat capacity of the second fluid is... The heat capacity is 4190.08 J / (kg·K), and the heat flow rate is 116.2 kW / K. The maximum heat transfer under ideal conditions is the smaller of the heat capacity flow rates on the inner and outer sides of the plate, which is 58.3 kW / K. The power is 408.08 kW, and the heat exchange efficiency is assumed to be... The value is 0.8. Based on the temperature information of the first fluid and the second fluid, the total heat exchange is calculated to be 326.4 kW. The outlet temperature of the first fluid inside the plate is 285.34 K, and the outlet temperature of the second fluid outside the plate is 286.7 K.

[0023] Specifically, the structural parameters of the concentric circular bulging plate heat exchanger include: the cross-sectional distance of the flow direction of the heat exchange medium flow chamber arranged in opposite directions at a long distance from the weld point pitch 2. S T Flow direction axial weld pitch 2 S L Maximum bulge height h max Solder joint diameter d ws The width (height) of the heat exchanger plates W p Plate thickness S w2 innermost diameter D in Number of heat exchanger rings N Spacing between two adjacent heat exchange plates ΔR Number of times the serpentine flow N flow ; In this embodiment of the invention, the cross-section of the flow direction is 2 mm away from the weld point pitch. S T The axial weld pitch is 72mm, and the flow direction axial weld pitch is 2.S L The maximum bulge height is 42mm. h max The diameter of the solder joint is 9mm. d ws The plate width (height) of the heat exchanger is 10mm. W p 1500mm, plate thickness S w2 The innermost diameter is 3mm. D in 400mm, number of heat exchanger coils N The value is 9, and the spacing between two adjacent heat exchange plates is... ΔR For 100mm, the number of zigzag flow patterns is... N flow It was 7 times.

[0024] Specifically, the operating parameters of the concentric circular bulging plate heat exchanger include: the name of the clean working fluid inside the plate, and the inlet temperature. T cin Inlet pressure P cin Volumetric flow rate V cin Name of clean working fluid outside the plate, inlet temperature T sin Inlet pressure P sin Volumetric flow rate V sin ; Rotational angular velocity of the agitator ω .

[0025] In this embodiment of the invention, the first fluid inside the plate is a clean working fluid—water, with an inlet temperature of... T cin The inlet pressure is 281.15K. P cin The pressure is 0.4 MPa, and the volumetric flow rate is... V cin 50m 3 / h; The second fluid outside the plate is a non-clean working fluid - domestic sewage, inlet temperature T sin The inlet pressure is 288.15K. P sin 0.1 MPa, volumetric flow rate V sin 100m 3 / h; angular velocity of the agitator ωAt a speed of 20 r / min, the linear velocities of the second fluid outside the plate, based on the center of the two adjacent rings outside the plate, are [0.31, 0.52, 0.73, 0.94, 1.15, 1.36, 1.57, 1.78, 1.99] from the inner ring, with units of m / s.

[0026] Specifically, the convective heat transfer coefficient and Fanning friction factor of the first fluid are calculated based on the structural and operating parameters of the concentric circular bulging plate heat exchanger, including: The convective heat transfer coefficient is determined using the following formula. h (Unit: W / (m²·K)): (4) in, For Nusselt numbers; is the thermal conductivity of the fluid, expressed in W / (m·K); The hydraulic diameter is expressed in meters (m).

[0027] Heat is transferred from the first fluid inside the plate to the second fluid outside the plate. The overall heat transfer coefficient of the heat exchanger is... U (The unit is W / (m²·K)) is determined by the following formula: (5) in, The convective heat transfer coefficient on the inner side of the plate is expressed in W / (m²·K). The convective heat transfer coefficient on the outer side of the plate is expressed in W / (m²·K). The thickness of the metal plate wall is expressed in meters (m). is the thermal conductivity of the metal, expressed in W / (m·K); The fouling thermal resistance is expressed in (m²·K) / W.

[0028] When a fluid flows in a pipe, pressure loss occurs due to friction; this pressure drop is the fluid's pressure drop. (Unit: Pa) is: (6) in, Fanning friction factor; This refers to the fluid density, expressed in kg / m³. The fluid velocity is expressed in m / s. The length of the flow is in meters (m).

[0029] Among them, the Fanning friction factor of the first fluid inside the plate for: (7) in, , This is an intermediate variable, related to the geometry of the heat exchanger plate, and is specifically determined by the following formula: (8) (9) in, , , , The fitting coefficients are related to the geometry of the heat exchanger plate. The laminar flow contribution coefficient. For the transition zone coefficient, This is the turbulence correction factor. The coefficients are logarithmic function coefficients. The correction factors for the denominator are determined by the following formulas: (10) (11) (12) (13) (14) The above formulas were obtained by fitting experimental data.

[0030] c 1 The density of solder joints is determined by the following formula: (15) in, S L It is half the pitch of the axial weld point in the flow direction; It is half the distance between the cross-section in the flow direction and the weld point pitch; The diameter of the solder joint.

[0031] c 2 The bulge degree of the bulge plate is determined by the following formula: (16) in, This is the maximum net height of the bulge.

[0032] Spacing ratio of solder joints for: (17) When ≈0.58, the solder joints are nearly square-shaped; When ≈1, the spacing between solder joints is equal; When the value is approximately 1.71, the solder joints are arranged in a rectangular pattern. According to... Which interval does the value fall into, and what are the subsequent... Nu The formula will choose different fitting coefficients.

[0033] ratio of weld joint diameter to weld joint transverse pitch B for: (18) The ratio of the maximum bulging height inside the bulging plate to the transverse pitch of the weld point C for: (19) Nusselt number on the inside of the plate Nu for: (20) in, Re The Reynolds number is... Pr It is a Prandtl number; when When ≈0.58, , , They are determined by the following formulas respectively: (twenty one) (twenty two) (twenty three) (twenty four) when When ≈1, , , They are determined by the following formulas respectively: (25) (26) (27) (28) when When ≈1.71, , , They are determined by the following formulas respectively: (29) (30) (31) (32) Fanning friction factor of the second fluid outside the plate f Determined by the following formula: (33) Nusel number Nu Determined by the following formula: (34) in, The Nusselt number for the laminar flow region; For the Nusselt number of the transition region; The baseline Nusselt number.

[0034] In this embodiment of the invention, the Reynolds number of the clean working fluid inside the plate is calculated based on structural parameters and operating parameters. Re The Prandtl number is 12127. Pr The hydraulic diameter is 9.2. Dh in It is 1.2cm; Reynolds number of non-clean working fluid on the inner and outer sides of the plate Re The Prandtl number is [99359,71423,102275,133251,164290,195364,226460,257571,288692]. Pr The average hydraulic diameter is 8.44 on the outer and inner sides of the plate. Dh off1 It is 16.5 cm (where the average hydraulic diameter of the innermost circle is 16.5 cm). Dh off2 The unilateral convective heat transfer coefficient is [1427,2174,2911,3620,4310,4984,5646,6297,6939] (37cm). Reynolds number of non-clean working fluid on the outer side of the plate Re [89488,119834,150591,181511,212512,243559,274635,305730,0], Prandtl number Pr The average hydraulic diameter on the outer side of the plate is 8.44. Dh off3 The value is 19.2 cm, and the unilateral convective heat transfer coefficient is [2175,2911,3621,4311,4985,5648,6299,6941,0].

[0035] According to the definition of hydraulic diameter Dh Determined by the following formula: (35) in, S 横截 Let be the cross-sectional area of ​​the working fluid. χ For the wetted perimeter of the working fluid, V 流通Let be the flow volume of the working fluid. S 传热 The heat transfer area of ​​the working fluid; since the inner and outer sides of the plate are arranged in concentric circles, the flow volume is different, and the hydraulic diameter is also different.

[0036] S2, Divide each of the aforementioned expanded heat exchange plates into... M Grids, each grid including the _ ... i inner side of the ring plate, the first i The inner and outer sides of the i-th ring plate and the outer side of the i-th ring plate i =1,2,…, N Each grid is called a three-stream heat transfer element; based on the total heat transfer coefficient, the inner heat transfer coefficient of the inner side of the plate to the outer side of the plate for each three-stream heat transfer element, and the outer heat transfer coefficient of the inner side of the plate to the outer side of the plate for each three-stream heat transfer element are calculated.

[0037] Specifically, the first fluid outlet temperature array of the first fluid inside the heat exchanger plate is defined as follows: T oip , No. i The first fluid outlet temperature array of the circle is T oip [ i ],but T oip =[ T oip [ 1 ]、 T oip [ 2 ]、… T oip [ i ]、…、 T oip [ N The first fluid outlet temperature array for each revolution T oip [ i [Includes the first] i In the circle M The temperature information of the first fluid outlet within the plate of each grid cell. i After the heat exchange plates are laid out flat, they are divided into four columns numbered 3, 4, 1, and 2 from left to right. T oip [ i ]for i An array of 4 rows and 4 columns. This includes the array of outlet temperatures at the center-to-center distance between the inner and outer sides of the fluid outside the plate. T oiop Array of outlet temperatures at the center distance of the fluid outside the plate T ooop array of outlet temperature values ​​of fluid inside the plate T oipThe outlet temperature data is stored in the same way.

[0038] In this embodiment of the invention, a first fluid outlet temperature array is pre-defined before iteration. T oip Array of outlet temperatures for the center-to-center distance between the inner and outer sides of the fluid outside the plate T oiop Array of outlet temperatures at the center distance of the fluid outside the plate T ooop Allocate free memory and set the first fluid outlet temperature inside the plate and the second fluid outlet temperature outside the plate, estimated in step S1, as initial values. Preset the relative deviation of the average first fluid outlet temperature inside the plate for each heat exchanger cycle calculated in the two iterations to 1. The iteration converges when the relative deviation... Rel Set it to 0.01% and begin iterative calculation.

[0039] In this embodiment of the invention, according to as follows Figure 6 or Figure 7 The columns are divided into rows and columns, and the columns can be divided from left to right according to the spiral flow direction of the second fluid outside the plate as [3, 4, 1, 2]. By meshing half a circle of each spiral heat transfer element in each ring, the total thermal conductivity of the three flow heat transfer elements from the innermost to the outermost ring of the plate (inside the plate and outside the plate) in columns 2 and 3 is obtained. U in The array is [1134.5,1532.2,1844.5,2091.2,2292.4,2460.6,2603.6,2727.1,2835], and the overall heat transfer coefficient is... UA in The array is [18.9,37.3,64.1,94.6,127.6,162.6,170.8,203.3,236.7]; the total thermal conductivity of the three-stream heat transfer element between the inside and outside of the plate. U out The array is [1532.6,1844.8,2091.5,2292.8,2460.9,2604,2727.5,2835.4,0], and the overall heat transfer coefficient is... UA out The array is [25.5,44.9,72.7,103.7,137,172.1,178.9,211.4,0]; the total thermal conductivity of the three-stream heat transfer micro-element from the innermost to the outermost plate, from the innermost to the outermost plate, is obtained in columns 4 and 1. U in The array is [1134.5,1532.2,1844.5,2091.2,2292.4,2460.6,2603.6,2727.1,2835], and the overall heat transfer coefficient is... UA inThe array is [9.2, 10.3, 12.4, 14.1, 15.5, 16.6, 15, 15.8, 16.4]; the total thermal conductivity of the three-stream heat transfer element between the inside and outside of the plate. U out The array is [1532.6,1844.8,2091.5,2292.7,2460.9,2604,2727.5,2835.4,0], and the overall heat transfer coefficient is... UA out The array is [12.4,12.4,14.1,15.5,16.6,17.6,15.8,16.4,0].

[0040] S3. Based on the heat transfer coefficients of the inner and outer sides, first along the first... i The two second fluid streams, one on the inner side and the other on the outer side of the concentric circular bulging plate heat exchanger, flow in spiral directions from the bottom inlet to the top outlet of the heat exchanger. Calculate the direction of the second fluid. i The outlet temperatures of the two second fluids in each three-stream heat exchange element are calculated; then, along the first fluid from the first... i From the right side of the centerline of the bulging heat exchange plate of the ring, from the bottom inlet of the first half of the ring to the bottom outlet of the first half of the ring, and then from the... N +1- i Calculate the flow direction of the equal flow path from the left side of the centerline of the expanded heat exchange plate of the second half of the ring, from the bottom inlet of the second half of the ring to the bottom outlet of the second half of the ring. i Circle the outlet temperature of the first fluid in each three-flow heat exchange micro-element; repeat S3 until... i = N ; .

[0041] Specifically, starting from the innermost circle to the outermost circle, for each i lock up( i =1,2,3,…, N First, the verification calculation is completed from the inlet to the outlet along the spiral flow direction of the second fluid outside the plate; then, the entire process is completed along the flow direction of the fluid inside the plate in the first half of each revolution (the first...). i The first half of the circle, half of the heat exchange zone + the first half N - i +1 (half of the heat exchange zone in the second half of the circle), that is, along each i The flow paths of the spiral flow path outside the plate and the heat exchange flow path inside the plate are calculated once each, and the temperature field calculated for each heat exchange micro-element is updated. The results are recorded. i The average outlet value of the fluid within the ring plate is used to complete this... i After the loop iteration, calculate the first... i +1 lap, recording the 1st lap i The average outlet value of the fluid within the +1 ring plate is calculated until the outermost ring is completed, at which point the iteration ends.

[0042] Among them, the calculation of the first i The outlet temperature of the first fluid in each of the three-stream heat exchange micro-elements is as follows: Along each i Circle the flow path direction of the second fluid and calculate the temperature field of each of the three flow heat exchange micro-elements; Along the first i Circle the flow direction of the first fluid, and calculate the sequential flow through the first... i The heat exchange zone in the first half of the circle and the first half N - i The outlet temperature of the first fluid in the second half of the heat exchange zone of +1 turn.

[0043] Among them, along each i Determine the flow path direction of the second fluid, and calculate the temperature field of each of the three-stream heat transfer micro-elements, including: Let each i The second virtual flow circle number is s [ i ]; Incrementing iteration variable iter [ i ]( iter [ i ]=1,2,3,…, s [ i Define the virtual process number of the fluid as... pass [ i This is used to determine which serpentine back-and-forth motion the first fluid inside the plate is currently in.

[0044] Starting from the bottom inlet of the concentric circular expansion plate heat exchanger, the second fluid flows along... iter [ i After each concentric spiral flows through one revolution, it moves up one row until the spiral flows to... s [ i Each column flows out from the top outlet of the concentric circular bulging plate heat exchanger, and the flow path of the second fluid outside the plate is as follows: Figure 8 As shown.

[0045] In this embodiment of the invention, the number of cycles in the incrementing iteration variable... i ( i =1,2,3,…, N Internally, it uses a parallel two-round iterative computation setup. For example... Figure 7 As shown, the first round of iterations mainly follows the... i The fluid spiral flow direction on the inner and outer sides of the bulging heat exchange plate is from the bottom inlet to the top outlet of the concentric circular heat exchanger; the second iteration first follows the... iThe fluid flow direction within the right side and the first half of the bulging heat exchange plate of the concentric circular heat exchanger flows from the 10a inlet at the bottom of the heat exchanger along the weld line boundary to the 10b outlet at the bottom, and then along the... N +1- i The 20a inlet on the left side of the bulging heat exchange plate of the ring flows along the weld line boundary to the 20b outlet at the bottom, and two rounds of iteration are completed.

[0046] For the first iteration, its incrementing iteration variable is: iter [ i [It is believed that the non-clean working fluid travels along the first...] iter [ i After the concentric spiral flow in columns 1, 2, 3, and 4 of row 1 completes a full circle, it moves upward by one cell. Therefore, the order of its row and column coordinate changes is: [ iter [ i ],1]、[ iter [ i ],2]、[ iter [ i ],3]、[ iter [ i ],4]、[ iter [ i ]+1,1]、…、 s [ i ],1]、 s [ i ],2]、 s [ i ],3]、 s [ i ],4].

[0047] Define each i Virtual flow time of the second fluid in the circle time [ i ] virtual ( i =1,2,3,…, N (Unit: s): (36) in, Width (height) of the heat exchange plate, in meters (m). This is the innermost diameter of the heat exchange plate, in meters (m). This represents the total number of heat exchanger coils. ΔR The distance between two adjacent heat exchange plates is in meters (m). This represents the volumetric flow rate of the non-clean working fluid outside the plate, expressed in m³ / s.

[0048] It should be noted that the upward vertical flow velocity of the non-clean fluid is the same, therefore the residence time (virtual flow time) in the heat exchanger is... time [i ] virtual It's the same.

[0049] Define each i Virtual total flow length of the circle L [ i ]( i =1,2,3,…, N ): L [ i ] (37) in, The angular velocity of the agitator is expressed in rad / s. For the heat exchange plate i The radius of the circle, in meters (m). This represents the virtual flow time, measured in seconds (s).

[0050] Define each i Virtual flow cycle number of the second fluid outside the plate, calculated by the loop. s [ i ]( i =1,2,3,…, N ): (38) in, This represents the virtual total flow length, in meters (m).

[0051] Define each i The rounded average number of virtual flow cycles within each virtual fluid path (rounded down). k [ i ]( i =1,2,3,…, N ): (39) in, The number of times the flow is zigzagging; This is the floor function.

[0052] Define each i The number of rounded virtual flow cycles of the second fluid outside the ring plate Q [ i ]( i =1,2,3,…, N ): (40) in, The number of virtual revolutions for each fluid (rounded down).

[0053] For the iThe number of virtual flow circles, rounded down, representing the fluid flow on the inner and outer sides of the plate, is denoted as [circle number]. Q [ i This represents the total number of rows in the grid. Define an incrementing loop variable. iter [ i Its value starts from 1 and increases by 1 each time, until... Q [ i "Up to" indicates the current line being processed. Next, calculate the virtual fluid path number of the current row, denoted as . pass [ i The calculation method uses the current line number. iter [ i Divide by the number of rows contained in each fluid virtual process. k [ i Then round down; the fluid virtual process number here refers to... Figure 6 , Figure 7 The blue or orange rectangular box in the middle; Then, according to pass [ i The parity of ] is used to define the flow direction type of the heat transfer micro-element in the first and second halves of the circle, respectively, and denoted as . ft and lt The rule is: if pass [ i If the number is odd, then the flow type in the first half of the circle is... ft Set as P1 The flow type in the second half of the circle lt Set as P2 ;if pass [ i If the number is even, then the flow type in the first half of the circle is... ft Set as P2 The flow type in the second half of the circle lt Set as P1 Here P1 and P2 These are two different flow patterns. P1 This indicates that the three fluids are flowing in the same direction. P2 This indicates that the middle fluid (the clean working fluid side inside the plate) flows in the opposite direction to the other two.

[0054] The first and second columns on the right are collectively called the "first half circle," and the third and fourth columns on the left are collectively called the "second half circle." For each row (by... iter [ i (specified) and each column (by column variable) k Specify, k (Choose 1, 2, 3, 4), and determine the flow direction type of the three heat exchange micro-elements. θ [ i[and the inlet temperature when the clean working fluid inside the plate enters the micro-element] T cin The specific rules are as follows: when k When =1 (Column 1, belonging to the first half of the circle, the clean working fluid inside the plate flows vertically upward): The flow direction type is fixed as P1 ; Value of the inlet temperature of the clean working fluid inside the plate: If the current position is row 1 ( iter [ i If ]=1), then the inlet temperature is equal to the total inlet temperature of the clean working fluid inside the plate. T cin Otherwise, the inlet temperature is equal to the previous line ( iter [ i -1) The outlet temperature in the same column (column 1), which is stored in an array. T oip [ i ][ iter [ i [-1,1] in.

[0055] when k When the value is 2 (2nd column, belonging to the first half of the circle, the fluid flows in a horizontal serpentine pattern): The flow type is determined by the flow type variable in the first half of the circle. ft Decision (i.e., based on) pass Odd or even P1 or P2 ); The inlet temperature value depends on the current fluid virtual process number. pass [ i The total number of serpentine flows equals the total number of serpentine flows. N flow (That is, it is already the last virtual fluid path), then the inlet temperature is equal to the last row of this loop (row number is...). Q [ i The outlet temperature in column 1; otherwise, the inlet temperature is equal to the row corresponding to the current loop that skips one virtual fluid path (row number is...). iter [ i ]- k [ i The second column of the outlet temperature.

[0056] when k When the value is 3 (3rd column, belonging to the second half of the circle, the fluid flows in a horizontal serpentine pattern): The flow type is determined by the flow type variable in the second half of the cycle. lt The decision (also based on the parity of the fluid virtual path number) is made. P1 or P2 ); The rules for determining the inlet temperature and k When =2, it is exactly the same, except that the column number becomes the 3rd column: if it is the last fluid virtual path number, take the outlet temperature of the 4th column of the last row of this loop; otherwise, take the outlet temperature of the 3rd column of the same row of the next fluid virtual path number.

[0057] when k When the value is 4 (4th column, belonging to the second half of the circle, the fluid flows vertically upward): The flow direction type is fixed as P1 ; Inlet temperature value: If the current row is 1 ( iter [ i If ]=1), then the inlet temperature needs to be obtained from the paired coils that achieve equal flow paths. The coil number of the paired coil is N +1- i Take the first column of the second pairing. k [ i The outlet temperatures of the first row (i.e., the number from row 1 to this row, which is also the first virtual fluid path number) are calculated, and the average of these temperatures is used as the inlet temperature of the current infinitesimal element. If it is not row 1, the inlet temperature is equal to the previous row ( iter [ i -1) The outlet temperature of the same column (column 4).

[0058] For each heat exchange micro-element, the corresponding system of simultaneous equations to be solved is as follows: (41) (42) (43) in, , , The sign coefficient characterizing the direction of fluid flow; The inlet temperature of the clean working fluid inside the plate, in K; The inlet temperature of the non-clean working fluid on the inner and outer sides of the plate is expressed in K. The inlet temperature of the non-clean working fluid on the outer side of the plate is expressed in K. x These are coordinates representing the flow direction, in meters (m). express and The product of the heat transfer coefficient between the two sides and the wetted perimeter, with units of W / (m·K); express and The product of the heat transfer coefficient between the two sides and the wetted perimeter, with units of W / (m·K); express The heat capacity flow rate, expressed in W / K; express The heat capacity flow rate, expressed in W / K; express The heat capacity flow rate is expressed in W / K.

[0059] for P1 : =1, =1, =1, meaning all three fluids flow in the same direction, all along... x Positive direction; for P2 : =1, =-1, =1, meaning the fluid on the outer side of the plate flows in the opposite direction to the other two fluids.

[0060] Specifically, along the first i Circle the flow direction of the first fluid, and calculate the sequential flow through the first... i The heat exchange zone in the first half of the circle and the first half N - i The outlet temperature of the first fluid in the second half of the heat exchange zone of +1 revolution includes: Define the decrementing iteration variable as iter [ j ]( iter [ j ]=1,2,3,…, s [ j ]); The first fluid begins at the bottom inlet of the concentric circular expansion plate heat exchanger, and flows along the... i The flow pattern moves vertically upwards from the first column to the top of the concentric circles, then flows downwards into the second column until it reaches the bottom outlet of the concentric circular bulging plate heat exchanger; then it enters the... N - i +1 ring of bulging heat exchange plate s [ j The water flows vertically upwards to the top of the heat exchanger plate, and then enters... s [ j The current flows downwards in column -1 until it reaches the first column, which then flows out from the bottom outlet of the concentric bulging plate heat exchanger.

[0061] In this embodiment of the invention, for the second iteration, the decrementing iteration variable is defined as... iter [ j For the first half of the circle, first go vertically upwards along the first column. iter [ i According to the auto-increment iteration to Q [ i ], that is, the order of its row and column coordinate changes is: [1,1], [2,1], ..., [ iter [i ],1]、[ iter [ i ]+1,1]、…、 s [ i ],1]; Then it enters the second column and flows downwards in a serpentine pattern. iter [ j The iteration decreases to 1, meaning the order of row and column coordinate changes is as follows: s [ i ],2]、[ Q [ i -1],2]、…、[ iter [ i ],2]、[ iter [ i [-1,2]、…、[2,2]、[1,2]、flow out from outlet 10b at the bottom of the heat exchanger; then, it enters the… N +1- i The fourth column of the bulging heat exchange plates in the ring flows vertically upwards. iter [ i According to the auto-increment iteration to Q [ N +1- i ], that is, the order of its row and column coordinate changes is: [1,4], [2,4], ..., [ iter [ i ],4]、[ iter [ i [+1,4]、...、[ Q [ N +1- i [,4]; Then it enters the 3rd column and flows downwards in a serpentine pattern. iter [ j The iteration decreases to 1, meaning the order of row and column coordinate changes is: [ Q [ N +1- i ],3]、[ Q [ N - i ],3]、…、[ iter [ i ],3]、[ iter [ i [-1,3]、…、[2,3]、[1,3]、flow out from outlet 20b at the bottom of the heat exchanger.

[0062] Perform heat transfer micro-element verification calculations for each corresponding row and column coordinate, update the fluid outlet temperature, and set it as the inlet temperature of the next micro-element. Iterate in this way until all micro-element calculations from the innermost to the outermost ring are completed.

[0063] S4, Calculation NThe first average value of the outlet temperature of the first fluid, or calculated N The second average value of the outlet temperature of the second fluid.

[0064] According to the law of conservation of energy, when the heat exchanger reaches a stable operating state, the heat exchange between the first fluid side inside the plate and the second fluid side outside the plate is equivalent in the sense of energy conservation; that is, the heat absorbed by the inner side of the plate is equal to the heat released by the outer side of the plate. Therefore, convergence can be determined by using either the average outlet temperature of the first fluid side inside the plate or the integral average outlet temperature of the second fluid side outside the plate. In this embodiment of the invention, the outlet temperature of the first fluid inside the plate is used as the convergence criterion; that is, when the relative deviation of the first average value obtained from two adjacent iterations is less than 0.01%, the temperature field is considered to have converged.

[0065] In this embodiment of the invention, T oip The average temperature of the fluid in each branch within the plate is calculated, and the integral average temperature of the outlet of the non-clean working fluid outside the plate is also calculated. Specifically, the average temperature of the fluid in each branch within the plate is calculated. T oip The average of the fluid temperature values ​​stored in each branch is used to obtain a first average value; simultaneously, the outlet temperature of the non-clean working fluid outside the plate is integrated and averaged to obtain a second average value. The first average value is used for convergence judgment, and the second average value is used to output the overall performance parameters of the heat exchanger.

[0066] S5. Execute steps S3-S4 until the ratio of the two first average values ​​to the second average value is less than the preset deviation threshold, and record the calculated value of the three-dimensional temperature field.

[0067] Specifically, the relative deviation between the in-plate or out-of-plate outlet temperature values ​​obtained from the two rounds of calculation is calculated. When the relative deviation of this round is greater than... Rel If the value is less than 1, continue to the next iteration; if the value is less than 1, continue to the next iteration. Rel When the value is reached, the iteration stops, the calculation exits, and the calculated three-dimensional temperature field value is saved.

[0068] Similarly, this embodiment of the invention uses the outlet temperature of the first fluid within the plate as a convergence criterion. The numerical variable of the outlet temperature of the clean working fluid within the plate is defined. T oipN Then the first i The outlet temperature value of each flow path T oipN [ i ]: (44) (45) in, This is an array of clean working fluid outlet temperatures obtained from the previous iteration. If... RelIf it is greater than 0.01%, continue iterative calculation; if Rel If the result is less than or equal to 0.01%, stop the iteration, save the three-dimensional temperature field data, and exit.

[0069] In this embodiment of the invention, from the innermost ring to the outermost ring, along the flow direction of the second fluid outside the plate and the flow direction of the first fluid inside the plate, each three-flow heat exchange micro-element is checked and calculated. The outlet temperature values ​​of each flow path inside the plate obtained in each round of calculation are shown in Table 1. It can be seen that when the number of iterations is 18, the outlet temperature values ​​of the flow paths inside the plate are [285.31, 287.10, 286.99, 287.01, 286.91, 286.85, 286.88, 286.98, 286.07], and the corresponding iteration deviation is 0.073%. The trend of the relative deviation between two adjacent iterations with the number of iterations is shown in the figure below. Figure 9 As shown.

[0070] Table 1

[0071] For the first fluid in a concentric circular expansion plate heat exchanger, the first... i Half circle and the first circle N - i The +1 half-circle combined flow pattern involves the flow stream switching to the paired half-circle for heat exchange after completing the heat exchange in the first half-circle via the bottom pipe. The flow path is interrupted and reset during the circle switching. Additionally, the second fluid, while flowing vertically upwards from the bottom of the cylinder, also exhibits a spiral upward flow due to the rotation of the top motor. This invention addresses this by dividing each circle of expanded heat exchange plates into four columns and alternately performing heat transfer calculations in two directions: along the spiral flow path outside the plates and the serpentine cross-circle flow path inside the plates. This accurately reflects the coupled heat transfer relationship between the three-dimensional serpentine cross-circle flow inside the plates and the spiral upward flow outside the plates, thus solving the problem caused by the three-dimensional combined flow pattern. The present invention addresses the problem of temperature field calculation being impossible due to the different linear velocities of each ring in a concentric cylindrical structure, which leads to varying heat transfer coefficients and makes verification calculations extremely difficult. It constructs a three-flow heat transfer micro-element model consisting of a first fluid inside the plate, a second fluid on the inner side of the plate, and a second fluid on the outer side of the plate. The heat transfer coefficient and outlet temperature of each ring are calculated separately, characterizing the differences in heat transfer performance of each ring in the radial direction. Based on the parity of the fluid virtual path number, the flow direction type of the first and second halves of the ring is dynamically switched, accurately simulating the flow of the first fluid "first vertically upward along the first column, then horizontally downward in a serpentine pattern along the second column, crossing rings to the [missing information]." N - iThe complex three-dimensional flow path, which involves "vertically moving upward along the fourth column after +1 revolution and then serpentine downward along the third column," enables precise verification of the outlet temperature of each branch. Through iterative calculations until the first average value obtained from the two previous cycles is less than the preset deviation threshold, the outlet temperature distribution data of each branch in each layer is output, providing a reliable three-dimensional temperature field verification basis for the optimized design of the concentric circular expansion plate heat exchanger.

[0072] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for calculating and verifying the three-dimensional temperature field of a concentric circular bulging plate heat exchanger, wherein the concentric circular bulging plate heat exchanger comprises... N A concentric circle of expanding heat exchange plates, N The aforementioned expanding heat exchange plates are sequentially arranged radially from the inside to the outside, wherein the working fluid inside the expanding heat exchange plates is a first fluid, and the working fluid outside the expanding heat exchange plates is a second fluid, characterized in that... The method includes: S1. Based on the structural and operating parameters of the concentric circular expansion plate heat exchanger, calculate the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid, and calculate the total heat transfer coefficient based on the convective heat transfer coefficient of the first fluid and the convective heat transfer coefficient of the second fluid. S2, Divide each of the aforementioned expanded heat exchange plates into... M Grids, each grid including the _ ... i inner side of the ring plate, the first i The outer and inner sides of the ring plate and the first i outer and outer sides of the ring plate i =1,2,…, N Each grid is called a three-stream heat transfer element; based on the total heat transfer coefficient, the inner heat transfer coefficient of each three-stream heat transfer element from the inside of the plate to the outside of the plate, and the outer heat transfer coefficient of each three-stream heat transfer element from the inside of the plate to the outside of the plate are calculated. S3. Based on the inner heat transfer coefficient and the outer heat transfer coefficient, first along the first... i The two second fluid streams, one on the inner side and the other on the outer side of the concentric circular bulging plate heat exchanger, flow spirally from the bottom inlet to the top outlet of the heat exchanger. Calculate the direction of the second fluid flow. i Circle the outlet temperature values ​​of the two second fluids of each of the three-stream heat exchange micro-elements; then follow the first fluid from the first... i From the right side of the centerline of the bulging heat exchange plate of the ring, from the bottom inlet of the first half of the ring to the bottom outlet of the first half of the ring, and then from the... N +1- i Calculate the flow direction of the equal flow path from the left side of the centerline of the expanded heat exchange plate of the second half of the ring, from the bottom inlet of the second half of the ring to the bottom outlet of the second half of the ring. i Circle the outlet temperature of the first fluid in each of the three-stream heat exchange micro-elements; repeat S3 until... i = N ; S4, Calculation N The first average value of the outlet temperature of the first fluid, or calculated N The second average value of the outlet temperature of the second fluid; S5. Execute steps S3-S4 until the ratio of the two first average values ​​to the second average value is less than the preset deviation threshold, and record the calculated value of the three-dimensional temperature field.

2. The method according to claim 1, characterized in that, Before calculating the convective heat transfer coefficients of the first fluid and the second fluid, the following steps are also included: The total heat exchange capacity of the concentric circular bulging plate heat exchanger, the first fluid outlet temperature inside the plate, and the second fluid outlet temperature outside the plate are estimated based on the preset heat exchange effectiveness as the initial values ​​for iterative calculation.

3. The method according to claim 1, characterized in that, Calculate the first i The outlet temperature of the first fluid in each of the three-stream heat exchange micro-elements is as follows: Along each i Circle the flow path direction of the second fluid and calculate the temperature field of each of the three flow heat exchange micro-elements; Along the first i Circle the flow direction of the first fluid, and calculate the sequential flow through the first... i The heat exchange zone in the first half of the circle and the first half N - i The outlet temperature of the first fluid in the second half of the heat exchange zone of +1 turn.

4. The method according to claim 3, characterized in that, Along each i Determine the flow path direction of the second fluid, and calculate the temperature field of each of the three-stream heat transfer micro-elements, including: Let each i The second virtual flow circle number is s [ i ], incrementing iteration variable iter [ i ]( iter [ i ]=1,2,3,…, s [ i ]), defining the virtual process number of fluid. pass [ i ]; Starting from the bottom inlet of the concentric circular expansion plate heat exchanger, the second fluid flows along... iter [ i After each concentric spiral flows through one revolution, it moves up one row until the spiral flows to... s [ i Each column flows out from the top outlet of the concentric circular bulging plate heat exchanger.

5. The method according to claim 3, characterized in that, Along the first i Circle the flow direction of the first fluid, and calculate the sequential flow through the first... i The heat exchange zone in the first half of the circle and the first half N - i The outlet temperature of the first fluid in the second half of the heat exchange zone of +1 revolution includes: Define the decrementing iteration variable as iter [ j ]( iter [ j ]=1,2,3,…, s [ j ]); The first fluid begins at the bottom inlet of the concentric circular expansion plate heat exchanger, and flows along the... i The flow pattern moves vertically upwards from the first column to the top of the concentric circles, then flows downwards into the second column until it reaches the bottom outlet of the concentric circular bulging plate heat exchanger; then it enters the... N - i +1 ring of bulging heat exchange plate s [ j The water flows vertically upwards to the top of the heat exchanger plate, and then enters... s [ j The current flows downwards in column -1 until it reaches the first column, which then flows out from the bottom outlet of the concentric bulging plate heat exchanger.

6. The method according to claim 4, characterized in that, According to the fluid virtual path number pass [ i The parity of the flow pattern determines the flow direction type for the first and second halves of the cycle: When the fluid virtual path number is odd, the first half-circle flow direction type ft for P1 The latter half of the flow direction type lt for P2 ; When the fluid virtual path number is even, the first half-circle flow direction type ft for P2 The latter half of the flow direction type lt for P1 .

7. The method according to claim 6, characterized in that, For each three-stream heat exchange micro-element, based on its column number... k Determine the inlet temperature of the fluid inside the plate: when k When =1, the inlet temperature is taken from the total inlet temperature or the outlet temperature of the previous row in this column; when k =2 or k When =3, the inlet temperature is taken from the outlet temperature of the next fluid virtual path number or the outlet temperature of the last line of this loop. when k When the value is 4, the inlet temperature is taken from the first column of the second pairing ring. k [ i The average outlet temperature of the row or the outlet temperature of the row above in this column; in, k [ i The number of rows contained in each virtual fluid path, determined by the number of virtual flow loops. s [ i Divide by the number of serpentine flows N flow Then round down to get the result.

8. The method according to claim 1, characterized in that, The overall heat transfer coefficient of the concentric circular bulging plate heat exchanger is calculated based on the convective heat transfer coefficients of the first fluid and the second fluid.

9. The method according to claim 1, characterized in that, While recording the calculated values ​​of the three-dimensional temperature field, the outlet temperature distribution data of each branch of the first fluid in each layer are also output to verify the uniform distribution effect of the equal flow path design.

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