Method and device for checking the heat exchange system of an immersed combustion gasifier

Abstract

This application discloses a method and apparatus for verifying the heat exchange system of a submerged combustion gasifier, belonging to the field of heat exchanger technology. The method includes: obtaining the structural parameters of the heat exchange tube based on a pre-designed heat exchange area; meshing the heat exchange tube model along its extension direction to obtain multiple micro-segments; obtaining the temperature parameters of each micro-segment and the total heat transfer coefficient of each micro-segment based on the structural parameters; if the temperature parameters and total heat transfer coefficient of each micro-segment do not meet the current design conditions, adjusting the heat exchange area and re-obtaining the structural parameters of the heat exchange tube based on the adjusted heat exchange area, until the temperature parameters and total heat transfer coefficient of each micro-segment meet the current design conditions, thus obtaining the target parameters of the heat exchange tube. This application can more accurately obtain the heat exchange capacity, temperature field, and heat transfer coefficient of the heat exchange tube, thereby making the verification process more closely aligned with actual operating conditions, more reliable, and improving design efficiency.

Description

Technical Field

[0001] This application relates to the field of heat exchanger technology, specifically to a method and apparatus for verifying the heat exchange system of a submerged combustion gasifier. Background Technology

[0002] Submerged combustion gasifiers are efficient and compact liquefied natural gas (LNG) gasification devices widely used in the regasification process of LNG receiving terminals. Submerged combustion gasifiers primarily work by immersing LNG in water, utilizing the heat generated from combustion to heat the LNG and convert it into gaseous natural gas.

[0003] Submerged combustion gasifiers complete the heat exchange process through a heat exchange system. Before being put into formal use, the structural parameters of the heat exchange system usually need to be checked to ensure that they meet the heat exchange requirements. The traditional check method mainly uses the average value of the inlet and outlet temperatures of the heat exchange tubes as the qualitative temperature inside the tubes. However, under supercritical pressure conditions, because the physical properties change drastically with temperature, this method can no longer meet the requirements for accurate calculation, resulting in a serious deviation between the checked results and the actual situation, affecting the reliability of the system. Summary of the Invention

[0004] The embodiments of this application provide a method and apparatus for verifying the heat exchange system of a submerged combustion gasifier, in order to solve the technical problem that the verification results of the prior art deviate significantly from the actual situation, affecting the reliability of the system.

[0005] To address the aforementioned technical problems, embodiments of this application disclose the following technical solutions:

[0006] In a first aspect, a method for verifying the heat exchange system of a submerged combustion gasifier is provided, the heat exchange system comprising heat exchange tubes; the method includes:

[0007] The structural parameters of the heat exchange tube are obtained based on the pre-designed heat exchange area;

[0008] Along the extension direction of the heat exchange tube, the model of the heat exchange tube is meshed to obtain multiple micro-segments;

[0009] Based on the structural parameters, the temperature parameters of each micro-segment and the total heat transfer coefficient of each micro-segment are obtained.

[0010] If the temperature parameters and overall heat transfer coefficient of each micro-segment do not meet the current design conditions, the heat exchange area is adjusted, and the structural parameters of the heat exchange tube are re-obtained based on the adjusted heat exchange area.

[0011] If the temperature parameters and overall heat transfer coefficient of each micro-segment meet the current design conditions, then the structural parameters, the heat exchange area, and the overall heat transfer coefficient of each micro-segment are determined as the target parameters of the heat exchange tube.

[0012] In conjunction with the first aspect, the temperature parameter includes the actual outlet temperature; obtaining the temperature parameter for each of the micro-segments includes:

[0013] For any of the aforementioned micro-segments, the first heat exchange is obtained based on the preset total heat transfer coefficient;

[0014] Based on the preset outlet temperature and inlet temperature of the micro-element segment, the inlet and outlet enthalpy difference is obtained.

[0015] The second heat exchange is obtained based on the inlet and outlet enthalpy difference;

[0016] If the relative error between the first heat exchange and the second heat exchange is less than the first preset threshold, then the preset outlet temperature is determined as the actual outlet temperature of the micro-segment.

[0017] In conjunction with the first aspect, the method further includes:

[0018] If the relative error between the first heat exchange and the second heat exchange is greater than or equal to the first preset threshold, then the predicted outlet temperature of the micro-element segment is obtained.

[0019] Set the preset outlet temperature of the micro-segment to the predicted outlet temperature, and re-execute the step of obtaining the first heat exchange based on the preset total heat transfer coefficient.

[0020] In conjunction with the first aspect, obtaining the first heat exchange based on the preset overall heat transfer coefficient includes:

[0021] The first heat exchange capacity is obtained using the following formula:

[0022] Q1=∫K i A i Δt mi

[0023] Where Q1 is the first heat exchanger, K i Let A be the preset overall heat transfer coefficient. i Let Δt be the inner wall area of ​​the infinitesimal segment. mi The logarithmic mean temperature difference of the micro-element segment.

[0024] In conjunction with the first aspect, based on the aforementioned inlet and outlet enthalpy difference, the second heat exchange is obtained, including:

[0025] The second heat exchanger is obtained using the following formula:

[0026] Q2=∫qm (h i+1 (t i+1 )-h i (t i ))

[0027] Where Q2 is the second heat exchanger, q m h is the mass flow rate of the fluid inside the pipe. i+1 (t i+1 ) represents the outlet enthalpy of the micro-element segment, h i (t i ) represents the inlet enthalpy of the micro-element segment, t i+1 t is the preset outlet temperature. i The inlet temperature is [value].

[0028] In conjunction with the first aspect, the temperature parameter also includes the actual inner wall temperature; obtaining the temperature parameter of each micro-segment further includes:

[0029] Based on the preset inner wall temperature of the micro-segment, the average temperature of the micro-segment, the inner wall area of ​​the micro-segment, and the initial heat transfer coefficient inside the tube, the third heat exchange of the micro-segment is obtained, and the average temperature is the average of the inlet temperature and the actual outlet temperature.

[0030] The fourth heat exchange of the micro-element segment is obtained based on the outer wall temperature, water bath temperature, outer wall area, and initial external heat transfer coefficient of the micro-element segment.

[0031] If the error between the third heat exchange and the fourth heat exchange is less than the second preset threshold, then the preset inner wall temperature is determined as the actual inner wall temperature of the micro-element segment.

[0032] In conjunction with the first aspect, the method further includes:

[0033] If the error between the third heat exchanger and the fourth heat exchanger is greater than or equal to the second preset threshold, then the predicted inner wall temperature of the micro-element segment is obtained.

[0034] Set the preset inner wall temperature of the micro-element segment to the predicted inner wall temperature, and re-execute the step of obtaining the third heat exchange of the micro-element segment based on the preset inner wall temperature of the micro-element segment, the average temperature of the micro-element segment, the inner wall area of ​​the micro-element segment, and the initial heat transfer coefficient inside the pipe.

[0035] In conjunction with the first aspect, based on the preset inner wall temperature of the micro-element segment, the average temperature of the micro-element segment, the inner wall area of ​​the micro-element segment, and the initial heat transfer coefficient inside the tube, the third heat exchange capacity of the micro-element segment is obtained, including:

[0036] The third heat exchanger is obtained using the following formula:

[0037] Q i =h i A i (t wi -t f )

[0038] Among them, Q i For the third heat exchange, h i Let A be the initial heat transfer coefficient inside the tube. i t is the inner wall area of ​​the infinitesimal segment. wi t is the preset inner wall temperature of the micro-element segment. f The average temperature of the micro-element segment.

[0039] In conjunction with the first aspect, based on the outer wall temperature, water bath temperature, outer wall area, and initial external heat transfer coefficient of the micro-element segment, the fourth heat exchange capacity of the micro-element segment is obtained, including:

[0040] The fourth heat exchanger is obtained using the following formula:

[0041] Q o =h o A o (t wo -t w )

[0042] Among them, Q o For the fourth heat exchange, h o Let A be the initial external heat transfer coefficient. o t is the area of ​​the outer wall. wo t is the outer wall temperature of the micro-element segment. w The water bath temperature is [value].

[0043] In conjunction with the first aspect, obtaining the total heat transfer coefficient of each of the micro-elements includes:

[0044] Based on the fouling thermal resistance of the inner wall of the tube, the fouling thermal resistance of the outer wall of the tube, the tube wall thermal resistance, the inner and outer tube diameters, the initial heat transfer coefficient inside the tube, and the initial heat transfer coefficient outside the tube of the micro-segment, the predicted total heat transfer coefficient is obtained.

[0045] If the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is less than a third preset threshold, then the initial total heat transfer coefficient is determined as the actual total heat transfer coefficient of the micro-element.

[0046] In conjunction with the first aspect, the method further includes:

[0047] If the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is greater than or equal to the third preset threshold, then the value of the preset total heat transfer coefficient is set to the value of the predicted total heat transfer coefficient, and the step of obtaining the first heat exchange based on the preset total heat transfer coefficient is re-executed.

[0048] In conjunction with the first aspect, based on the fouling thermal resistance of the inner wall of the tube, the fouling thermal resistance of the outer wall of the tube, the tube wall thermal resistance, the inner and outer tube diameters, the initial inner tube heat transfer coefficient, and the initial outer tube heat transfer coefficient of the tube segment, the predicted total heat transfer coefficient is obtained, including:

[0049] The predicted overall heat transfer coefficient is obtained using the following formula:

[0050]

[0051] Among them, K c Let d be the predicted total heat transfer coefficient. o Let d be the outer diameter of the heat exchange tube. i h is the inner diameter of the heat exchange tube. o Let h be the initial external heat transfer coefficient. i R is the initial heat transfer coefficient inside the tube. i R is the thermal resistance of the fouling on the inner wall of the pipe. w R is the thermal resistance of the tube wall. o d represents the thermal resistance of the fouling on the outer wall of the pipe. m The average diameter of the heat exchange tube is denoted as .

[0052] In conjunction with the first aspect, prior to the step of obtaining the structural parameters of the heat exchanger tube based on the pre-designed heat exchange area, the method further includes:

[0053] The heat exchange area is obtained based on the preset heat load.

[0054] Secondly, a verification device for the heat exchange system of a submerged combustion gasifier is provided, the heat exchange system comprising heat exchange tubes; the device includes:

[0055] The preliminary design module is used to obtain the structural parameters of the heat exchange tube based on the pre-designed heat exchange area;

[0056] The differential processing module is used to perform meshing processing on the model of the heat exchange tube along the extension direction of the heat exchange tube to obtain multiple micro-segments;

[0057] The micro-segment verification module is used to obtain the temperature parameters of each micro-segment and the total heat transfer coefficient of each micro-segment based on the structural parameters.

[0058] The verification and confirmation module is used to adjust the heat exchange area if the temperature parameters and total heat transfer coefficient of each micro-segment do not meet the current design conditions, and to re-obtain the structural parameters of the heat exchange tube based on the adjusted heat exchange area.

[0059] The verification module is further configured to determine the structural parameters, the heat exchange area, and the total heat transfer coefficient of each micro-segment as the target parameters of the heat exchange tube if the temperature parameters and total heat transfer coefficient of each micro-segment meet the current design conditions.

[0060] Compared with the prior art, the heat exchange system verification method of the submerged combustion gasifier of this application includes: obtaining the structural parameters of the heat exchange tube based on the pre-designed heat exchange area; performing mesh processing on the model of the heat exchange tube along the extension direction of the heat exchange tube to obtain multiple micro-segments; obtaining the temperature parameters of each micro-segment and the total heat transfer coefficient of each micro-segment based on the structural parameters; if the temperature parameters and total heat transfer coefficient of each micro-segment do not meet the current design conditions, adjusting the heat exchange area and re-obtaining the structural parameters of the heat exchange tube based on the adjusted heat exchange area; if the temperature parameters and total heat transfer coefficient of each micro-segment meet the current design conditions, determining the structural parameters, heat exchange area, and total heat transfer coefficient of each micro-segment as the target parameters of the heat exchange tube. The heat exchange system verification method provided in this application can divide the heat exchange tube into several micro-segments along the wire and perform iterative processing on each micro-segment based on thermal balance. This allows for more accurate acquisition of the heat exchange capacity, temperature field, and heat transfer coefficient of the heat exchange tube, making the verification process more consistent with actual working conditions, more reliable, and also conducive to improving design efficiency.

[0061] The heat exchange system verification device of the submerged combustion gasifier disclosed in this application can divide the heat exchange tube into several micro-segments along the path and perform iterative processing on each micro-segment based on thermal balance. This allows for more accurate acquisition of the heat exchange capacity, temperature field, and heat transfer coefficient of the heat exchange tube, making the verification process more consistent with actual working conditions, more reliable, and also conducive to improving design efficiency. Attached Figure Description

[0062] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is a schematic diagram of the heat exchange system of the submerged combustion gasifier in the embodiments of this application;

[0064] Figure 2This is a schematic diagram of the overall process for verifying the heat exchange system of a submerged combustion gasifier according to an embodiment of this application.

[0065] Figure 3 This is a schematic diagram of the process for obtaining the temperature parameters and overall heat transfer coefficient of a single micro-element in an embodiment of this application;

[0066] Figure 4 This is a schematic diagram of the structure of the heat exchange system verification device for the submerged combustion gasifier according to an embodiment of this application.

[0067] Figure label:

[0068] 10-Heat exchange tube; 20-Water bath; 30-Overflow weir; 401-Preliminary design module; 402-Differential processing module; 403-Micro element verification module; 404-Verification and confirmation module. Detailed Implementation

[0069] The technical solutions of the embodiments of this application 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 this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0070] In the description of this application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, and "at least one" can mean one, two, or more, unless otherwise explicitly specified.

[0071] Submerged combustion gasifiers primarily work by immersing LNG in water and using the heat generated from combustion to heat the LNG and convert it into gaseous natural gas. Specifically, the burner mixes fuel and air and ignites it to produce high-temperature combustion gases. These combustion gases enter the water through the burner nozzles, directly contacting the LNG and heating it to its vaporization temperature. During this process, the combustion gases are absorbed by the water, forming water vapor, while the LNG is heated and converted into gaseous natural gas.

[0072] Please see Figure 1 , Figure 1 This illustration shows the structure of the heat exchange system of the submerged combustion gasifier in this embodiment. The submerged combustion gasifier completes the heat exchange process through a heat exchange system, which typically includes heat exchange tubes 10, a water bath 20, and an overflow weir 30. Before being put into formal use, the structural parameters of the heat exchange system usually need to be checked to ensure that they meet the heat exchange requirements. The traditional check method mainly uses the average value of the inlet and outlet temperatures of the heat exchange tubes 10 as the qualitative temperature inside the tubes. However, under supercritical pressure conditions, due to the drastic changes in physical properties with temperature, this method can no longer meet the requirements for accurate calculation, resulting in a serious deviation between the checked results and the actual situation, affecting the reliability of the system.

[0073] In view of this, the present application provides a method for verifying the heat exchange system of a submerged combustion gasifier. By processing the heat exchange tube 10 into several micro-segments along the path of the heat exchange tube, and iterating each micro-segment based on thermal balance, the heat exchange capacity, temperature field and heat transfer coefficient of the heat exchange tube can be obtained more accurately. This makes the verification process more in line with actual working conditions and the verification more reliable, thereby solving at least some of the above-mentioned technical problems.

[0074] Please see Figure 2 , Figure 2 This illustration shows the overall flow of the heat exchange system verification method for a submerged combustion gasifier according to an embodiment of this application. The heat exchange system verification method for the submerged combustion gasifier includes the following steps:

[0075] Step 201: Obtain the structural parameters of the heat exchange tube 10 based on the pre-designed heat exchange area.

[0076] In some embodiments, before performing step 201, the method of this application embodiment may further include the following step: obtaining the heat exchange area based on a preset heat load.

[0077] By using the above method, the heat exchange area is calculated by first estimating the heat load, and then the structural parameters such as heat exchange tube 10, water bath 20 and overflow weir 30 are designed based on this, and the preliminary design of the heat exchange system can be quickly determined.

[0078] It should be noted that since the parameters of the heat exchange tube 10 have a more critical impact on the heat transfer coefficient, the method in this application embodiment is mainly verified from the perspective of the heat exchange tube 10.

[0079] For example, the structural parameters of the heat exchange tube 10 may include the inner diameter, outer diameter, and number of the heat exchange tube 10.

[0080] Step 202: Mesh the model of heat exchange tube 10 along its extension direction to obtain multiple micro-segments.

[0081] Specifically, a model of the heat exchanger tube 10 is created. Then, the model is differentiated and meshed, dividing the heat exchanger tube 10 into n micro-segments along its extension direction. Each micro-segment is a mesh element, representing a small geometric region on the heat exchanger tube 10.

[0082] By segmenting the heat exchange tube 10 in the above manner, it is possible to better fit the scenario where the physical properties change drastically with temperature under supercritical pressure conditions, thereby obtaining more accurate verification results.

[0083] Step 203: Based on the structural parameters, obtain the temperature parameters of each micro-segment and the total heat transfer coefficient of each micro-segment.

[0084] For example, the temperature parameters of each micro-segment may include the inlet temperature, actual outlet temperature, and actual inner wall temperature of each micro-segment.

[0085] Please see Figure 3 , Figure 3 This illustration demonstrates the process for obtaining the temperature parameters and overall heat transfer coefficient of a single micro-segment in an embodiment of this application. In some embodiments, the actual outlet temperature of each micro-segment can be obtained through the following steps:

[0086] Step 301: Set the preset total heat transfer coefficient for any micro-segment.

[0087] Step 302: Set the preset outlet temperature t i+1 For t i+1’ t i+1” Among them, t i+1’ The inlet temperature t of the micro-element segment i Add a local minimum value, preferably 0.1, i.e., t. i+1’ =t i +0.1; t i+1” The inlet temperature t of the micro-element segment i Add a maximum value, preferably 10, i.e., t. i+1” =t i +10.

[0088] Step 303: Obtain the first heat exchange based on the preset total heat transfer coefficient.

[0089] In some examples, the first heat exchange can be obtained using the following formula (1):

[0090] Q1=∫K i A i Δt mi (1)

[0091] In formula (1), Q1 is the first heat exchange, K i To preset the overall heat transfer coefficient, A i Let Δt be the inner wall area of ​​the infinitesimal segment. mi Let A be the logarithmic mean temperature difference of the infinitesimal segment. Wherein, the inner wall area A... i It can be calculated based on the inner diameter of the heat exchange tube 10.

[0092] For example, the logarithmic mean temperature difference is obtained by taking the logarithm of the inlet temperature of the hot fluid and the outlet temperature of the cold fluid, as well as the outlet temperature of the hot fluid and the inlet temperature of the cold fluid, and then calculating the average. The logarithmic mean temperature difference Δt of the infinitesimal segment. mi It can be obtained through the following formula (2):

[0093]

[0094] In formula (2), t w t represents the water bath temperature. i The inlet temperature of the micro-element segment is t. i+1 This is the preset outlet temperature.

[0095] Step 304: Based on the preset outlet temperature and inlet temperature of the micro-element segment, obtain the inlet and outlet enthalpy difference. And based on the inlet and outlet enthalpy difference, obtain the second heat exchange.

[0096] For example, the outlet enthalpy can be obtained by querying physical property data based on the preset outlet temperature of the micro-element segment, and the inlet enthalpy can be obtained by querying physical property data based on the inlet temperature of the micro-element segment. The difference between the outlet enthalpy and the inlet enthalpy is the inlet-outlet enthalpy difference.

[0097] The second heat exchange can be obtained using the following formula (3):

[0098] Q2=∫q m (h i+1 (t i+1 )-h i (t i (3)

[0099] In formula (3), Q2 is the second heat exchange, q m h is the mass flow rate of the fluid inside the pipe. i+1 (t i+1 ) represents the exit enthalpy of the infinitesimal segment, h i (t i ) represents the inlet enthalpy of the infinitesimal segment, t i+1 For the preset outlet temperature, t i This refers to the inlet temperature.

[0100] Step 305: Detect whether the relative error ε = (Q1-Q2) / 2 between the first heat exchanger and the second heat exchanger is less than a first preset threshold. If the relative error between the first heat exchanger and the second heat exchanger is less than the first preset threshold, proceed to step 306; if the relative error between the first heat exchanger and the second heat exchanger is greater than or equal to the first preset threshold, proceed to step 307.

[0101] For example, the first preset threshold can be ±0.01.

[0102] Step 306: Set the preset outlet temperature to the actual outlet temperature of the micro-element segment.

[0103] Step 307: Obtain the predicted outlet temperature of the micro-element. Then, set the preset outlet temperature of the micro-element to the predicted outlet temperature and repeat step 303.

[0104] Specifically, the predicted outlet temperature of this micro-element segment can be obtained through the following steps:

[0105] The bisection method is used to determine when the inlet temperature of the infinitesimal segment is t. i+1’ The heat transfer error is less than 0, and the inlet temperature of the micro-element is t. i+1” If the heat transfer error is greater than 0, then (t) is considered as follows: i+1’ +t i+1” Is the heat transfer error of ) / 2 greater than 0? If (t) i+1’ +t i+1” If the heat transfer error of ) / 2 is greater than 0, then t i+1’ =(t i+1’ +t i+1” ) / 2, t i+1” Remain unchanged; if (t) i+1’ +t i+1” If the heat transfer error of ) / 2 is less than 0, then t i+1’ t remains unchanged i+1” =(t i+1’ +t i+1” ) / 2.

[0106] In other words, if the relative error between the first heat exchanger and the second heat exchanger is greater than or equal to the first preset threshold, the predicted outlet temperature value is assigned to the preset outlet temperature, and a recursive loop is executed until the relative error between the first heat exchanger and the second heat exchanger is less than the first preset threshold.

[0107] It is understandable that, for any given infinitesimal segment, its actual outlet temperature should be the inlet temperature of the next infinitesimal segment. For the first infinitesimal segment, its inlet temperature is known.

[0108] In some embodiments, the actual inner wall temperature of each micro-segment can be obtained through the following steps:

[0109] Step 308: Set the preset inner wall temperature.

[0110] Step 309: Based on the preset inner wall temperature of the micro-segment, the average temperature of the micro-segment, the inner wall area of ​​the micro-segment, and the initial heat transfer coefficient inside the tube, obtain the third heat exchange of the micro-segment.

[0111] The qualitative temperature is the average of the inlet temperature and the actual outlet temperature.

[0112] In some examples, the third heat exchange is the heat exchange inside the heat exchange tube 10, which can be obtained by the following formula (4):

[0113] Q i =h i A i (t wi -t f (4)

[0114] In formula (4), Q i For the third heat exchange, A i Let t be the inner wall area of ​​the infinitesimal segment. wi t is the preset inner wall temperature of the micro-element segment. f Let t be the average inlet and outlet temperature of the micro-element segment. f =(t i +t i+1 ) / 2, h i The initial heat transfer coefficient inside the pipe is calculated using the following formula (5):

[0115]

[0116] In formula (5), λ i The thermal conductivity of the fluid at the average inlet and outlet temperatures within the micro-element pipe segment can be found using physical properties. i For the inner diameter of the heat exchange tube, Nu i The widely used forced convection heat transfer model for pipes is the Sieder-Tate heat transfer model, which takes into account the influence of wall inhomogeneities on heat transfer. Equation (6) is shown below:

[0117]

[0118] In formula (6), the qualitative temperature Nu i Re represents the average temperature of the fluid inlet and outlet within the micro-element tube. f Pr is the fluid Reynolds number. f μ is the Prandtl number of the fluid. f and μ w These are the viscosity of the fluid at the characteristic temperature and the wall temperature, respectively.

[0119] Step 310: Based on the outer wall temperature, water bath temperature, outer wall area, and initial tube heat transfer coefficient of the micro-element, obtain the fourth heat exchange of the micro-element.

[0120] In some examples, the fourth heat exchange is the heat exchange outside the heat exchange tube 10, which can be obtained by the following formula (7):

[0121] Q o =h o A o (t wo -t w (7)

[0122] In formula (7), Q o For the fourth heat exchange, A o The outer wall area, t, can be calculated based on the outer diameter of the heat exchange tube 10. wo Let t be the outer wall temperature of the infinitesimal segment. w The water bath temperature, h o The initial heat transfer coefficient outside the tube is calculated using the following formula (8):

[0123]

[0124] In formula (8), λ o Let d be the thermal conductivity of the gas-liquid two-phase flow. o For the outer diameter of the heat exchange tube, Nu o The heat transfer coefficient of the two-phase flow sweeping across the tube bundle outside the tube is calculated using the Zukauskas heat transfer model, and the calculation formula is shown in (9) below:

[0125]

[0126] In formula (9), Pr f The qualitative temperature is the average temperature of the fluid outside the pipe; Pr w The qualitative temperature is the outer wall temperature of the tube, Re f The maximum flow velocity is calculated at the smallest cross-section in the tube bundle.

[0127] Specifically, in this embodiment of the application, the preset overall heat transfer coefficient K i It is a preset value, and its value is related to the initial external heat transfer coefficient h. o Initial heat transfer coefficient h in the tube i The relationship between them is described in the following formula (11).

[0128] Step 311: Detect whether the error between the third and fourth heat exchangers is less than the second preset threshold. If the error between the third and fourth heat exchangers is less than the second preset threshold, proceed to step 312; if the error between the third and fourth heat exchangers is greater than or equal to the second preset threshold, proceed to step 313.

[0129] For example, the second preset threshold can be ±0.01.

[0130] Step 312: Determine the preset inner wall temperature as the actual inner wall temperature of the micro-element segment.

[0131] Step 313: Obtain the predicted inner wall temperature of the micro-element. Then, set the preset inner wall temperature of the micro-element to the predicted inner wall temperature and re-execute step 309.

[0132] Specifically, the predicted inner wall temperature of this micro-element segment can be obtained through the following steps:

[0133] Predict the inner wall temperature t o The inner wall temperature t can be predicted using the infinitesimal segment in step 308. o With respect to the outer wall temperature t of the micro-element segment o’ Interpolation yields t o =(t o +t o’ ) / 2, the outer wall temperature t of the micro-element segment o’ The calculation formula (10) is as follows:

[0134]

[0135] In other words, if the error between the third heat exchanger and the fourth heat exchanger is greater than or equal to the second preset threshold, the value of the predicted inner wall temperature in step 313 is assigned to the preset inner wall temperature in step 308, and a recursive loop is executed until the error between the third heat exchanger and the fourth heat exchanger is less than the second preset threshold.

[0136] In some embodiments, the total heat transfer coefficient of each micro-segment can be obtained by the following steps:

[0137] Step 314: Based on the fouling thermal resistance of the inner wall of the pipe, the fouling thermal resistance of the outer wall of the pipe, the pipe wall thermal resistance, the inner and outer pipe diameters, the initial inner heat transfer coefficient and the initial outer heat transfer coefficient of the pipe, obtain the predicted total heat transfer coefficient.

[0138] In some examples, the overall heat transfer coefficient inside and outside the tube is an important indicator for measuring the heat transfer performance of the SCV (Submerged Combustion Vaporizer). The heat transfer area of ​​the vaporizer is based on the outer surface area of ​​the tube. Under this premise, the predicted overall heat transfer coefficient can be obtained by the following formula (11):

[0139]

[0140] In formula (11), K c To predict the overall heat transfer coefficient, d o Let d be the outer diameter of the heat exchange tube.i h is the inner diameter of the heat exchange tube. o h is the initial external heat transfer coefficient. i R is the initial heat transfer coefficient inside the tube. i To reduce the thermal resistance of fouling on the inner wall of the pipe, R w R is the thermal resistance of the pipe wall. o For the thermal resistance of fouling on the outer wall of the pipe, d m This represents the average diameter of the heat exchange tubes.

[0141] For example, the thermal resistance R of fouling on the inner wall of the pipe i Thermal resistance R of fouling on the outer wall of the pipe o It can be determined in the following way:

[0142] Considering that the actual LNG is very clean, but there is ice formation on the outer wall, the thermal resistance R of fouling inside the pipe is ignored. i =0, reducing the thermal resistance R of external fouling. o =0.00009W / m 2 -K.

[0143] Step 315: Check whether the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is less than the third preset threshold. If the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is less than the third preset threshold, proceed to step 316; if the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is greater than or equal to the third preset threshold, proceed to step 317.

[0144] For example, the third preset threshold can be ±0.01.

[0145] Step 316: Determine the initial total heat transfer coefficient as the actual total heat transfer coefficient of the micro-element.

[0146] Step 317: Set the preset total heat transfer coefficient value to the predicted total heat transfer coefficient value, and repeat step 301.

[0147] In other words, the calculated predicted total heat transfer coefficient is compared with the preset total heat transfer coefficient. If the convergence condition is met, the iteration of the micro-element ends, and the outlet parameter of the micro-element is used as the inlet parameter of the next micro-element. If the predicted total heat transfer coefficient does not meet the convergence condition, the iteration should be returned to the starting position and the total heat transfer coefficient should be reset for solving.

[0148] Thus, using the above method, the heat exchange area is first estimated through heat load calculation, and structural parameters such as heat exchange tube 10, water bath 20, and overflow weir 30 are designed. Then, differential and gridded processing methods are used to perform segmented calculations along the heat exchange tube 10. By recursively iteratively solving for the temperature field of the infinitesimal segment and the overall heat transfer coefficient inside and outside the tube, the temperature field and heat transfer coefficient can be solved and corrected, further improving the accuracy and efficiency of the design.

[0149] Step 204: Check whether the temperature parameters and overall heat transfer coefficient of each micro-segment meet the current design conditions. If the temperature parameters and overall heat transfer coefficient of each micro-segment do not meet the current design conditions, proceed to step 205; if the temperature parameters and overall heat transfer coefficient of each micro-segment meet the current design conditions, proceed to step 206.

[0150] For example, the heat transfer calculation program is designed and verified using the operating conditions of the SCV. The structural parameters of the vaporizer are shown in the table below. The vaporizer has a total of 82 serpentine heat exchange tubes, each of which has 8 straight tubes and 7 bends. The program sets the number of straight tube segments per tube pass to 10, so the total number of segments is 80, n = 80.

[0151] parameter numerical values Inlet / outlet temperature (°C) -152 / 14 LNG flow rate (t / h) 188 LNG inlet pressure (MPa) 9.4 Number of heat exchange tubes 82 Heat exchanger tube specifications (mm × mm) Φ32×2.8 Effective straight tube length of heat exchanger (mm) 50.4 Pipe row horizontal spacing / vertical spacing (mm) 79.5 / 54

[0152] Step 205: Adjust the heat exchange area and re-obtain the structural parameters of the heat exchange tube 10 based on the adjusted heat exchange area.

[0153] Step 206: Determine the structural parameters, heat exchange area, and total heat transfer coefficient of each micro-segment as the target parameters of heat exchange tube 10.

[0154] It is understood that the method in this application embodiment, through differential and meshing processing along the heat exchange tube 10, and the iterative solution process based on the heat balance equation, can more accurately calculate the heat exchange, temperature field, and heat transfer coefficient, thereby improving the accuracy of the calculation results. Furthermore, by comparing the heat exchange tube temperature field obtained through heat exchange calculation with the overall heat transfer coefficient inside and outside the tube against the required design conditions, adjustments can be made to the structural design. This ensures that the heat exchange system can meet design requirements under supercritical pressure conditions, improving the system's reliability and performance.

[0155] Accordingly, please refer to Figure 4 , Figure 4 This diagram illustrates the structure of a heat exchange system verification device for a submerged combustion gasifier according to an embodiment of this application. The heat exchange system verification device for a submerged combustion gasifier provided in this embodiment includes a preliminary design module 401, a differential processing module 402, a micro-element verification module 403, and a verification confirmation module 404.

[0156] The preliminary design module 401 is used to obtain the structural parameters of the heat exchange tube based on the pre-designed heat exchange area.

[0157] The differential processing module 402 is used to perform meshing processing on the heat exchange tube model along the extension direction of the heat exchange tube to obtain multiple micro-segments.

[0158] The micro-segment verification module 403 is used to obtain the temperature parameters of each micro-segment based on the structural parameters, as well as the total heat transfer coefficient of each micro-segment.

[0159] The verification module 404 is used to adjust the heat exchange area if the temperature parameters and overall heat transfer coefficient of each micro-segment do not meet the current design conditions, and to re-obtain the structural parameters of the heat exchange tube based on the adjusted heat exchange area.

[0160] The verification module 404 is also used to determine the structural parameters, heat exchange area and total heat transfer coefficient of each micro-segment as the target parameters of the heat exchange tube if the temperature parameters and total heat transfer coefficient of each micro-segment meet the current design conditions.

[0161] In some embodiments, the temperature parameter includes the actual outlet temperature. The micro-element verification module 403 is specifically used for:

[0162] For any micro-element, the first heat exchange is obtained based on the preset total heat transfer coefficient.

[0163] The inlet and outlet enthalpy difference is obtained based on the preset outlet temperature and inlet temperature of the micro-element.

[0164] The second heat exchange is obtained based on the enthalpy difference between the inlet and outlet.

[0165] If the relative error between the first heat exchanger and the second heat exchanger is less than the first preset threshold, then the preset outlet temperature is determined as the actual outlet temperature of the micro-element segment.

[0166] In some embodiments, the micro-element segment verification module 403 is further used for:

[0167] If the relative error between the first heat exchanger and the second heat exchanger is greater than or equal to the first preset threshold, then the predicted outlet temperature of the micro-element segment is obtained.

[0168] Set the preset outlet temperature of the micro-element to the predicted outlet temperature, and re-execute the step of obtaining the first heat exchange based on the preset total heat transfer coefficient.

[0169] In some embodiments, the micro-element segment verification module 403 is specifically used for:

[0170] The first heat exchange is obtained using the following formula:

[0171] Q1=∫K i A i Δt mi

[0172] Where Q1 is the first heat exchanger, K i To preset the overall heat transfer coefficient, A i Let Δt be the inner wall area of ​​the infinitesimal segment. mi Let be the logarithmic mean temperature difference of the infinitesimal segment.

[0173] In some embodiments, the micro-element segment verification module 403 is specifically used for:

[0174] The second heat exchanger is obtained using the following formula:

[0175] Q2=∫q m (h i+1 (t i+1 )-h i (t i ))

[0176] Where Q2 is the second heat exchanger, q m h is the mass flow rate of the fluid inside the pipe. i+1 (t i+1 ) represents the exit enthalpy of the infinitesimal segment, h i (t i ) represents the inlet enthalpy of the infinitesimal segment, t i+1 For the preset outlet temperature, t i This refers to the inlet temperature.

[0177] In some embodiments, the temperature parameter also includes the actual inner wall temperature. The micro-element verification module 403 is further used for:

[0178] Based on the preset inner wall temperature of the micro-segment, the average temperature of the micro-segment, the inner wall area of ​​the micro-segment, and the initial heat transfer coefficient inside the tube, the third heat exchange of the micro-segment is obtained. The average temperature is the average of the inlet temperature and the actual outlet temperature.

[0179] The fourth heat exchange of the micro-element is obtained based on the outer wall temperature, water bath temperature, outer wall area, and initial external heat transfer coefficient of the micro-element.

[0180] If the error between the third and fourth heat exchangers is less than the second preset threshold, then the preset inner wall temperature is determined as the actual inner wall temperature of the micro-element segment.

[0181] In some embodiments, the micro-element segment verification module 403 is further used for:

[0182] If the error between the third and fourth heat exchangers is greater than or equal to the second preset threshold, the predicted inner wall temperature of the micro-element segment is obtained.

[0183] Set the preset inner wall temperature of the micro-element segment to the predicted inner wall temperature, and re-execute the step of obtaining the third heat exchange of the micro-element segment based on the preset inner wall temperature, the average temperature of the micro-element segment, the inner wall area of ​​the micro-element segment, and the initial heat transfer coefficient inside the pipe.

[0184] In some embodiments, the micro-element segment verification module 403 is specifically used for:

[0185] The third heat exchanger can be obtained using the following formula:

[0186] Qi =h i A i (t wi -t f )

[0187] Among them, Q i For the third heat exchange, h i Let A be the initial heat transfer coefficient inside the tube. i Let t be the inner wall area of ​​the infinitesimal segment. wi t is the preset inner wall temperature of the micro-element segment. f The average temperature of the micro-element segment.

[0188] In some embodiments, the micro-element segment verification module 403 is specifically used for:

[0189] The fourth heat exchanger is obtained using the following formula:

[0190] Q o =h o A o (t wo -t w )

[0191] Among them, Q o For the fourth heat exchange, h o Let A be the initial external heat transfer coefficient. o t represents the area of ​​the outer wall. wo Let t be the outer wall temperature of the infinitesimal segment. w This refers to the water bath temperature.

[0192] In some embodiments, the micro-element segment verification module 403 is specifically used for:

[0193] Based on the fouling thermal resistance of the inner wall of the pipe, the fouling thermal resistance of the outer wall of the pipe, the pipe wall thermal resistance, the inner and outer pipe diameters, the initial heat transfer coefficient inside the pipe, and the initial heat transfer coefficient outside the pipe of the micro-segment, the predicted total heat transfer coefficient is obtained.

[0194] If the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is less than the third preset threshold, then the initial total heat transfer coefficient is determined as the actual total heat transfer coefficient of the micro-element.

[0195] In some embodiments, the micro-element segment verification module 403 is further used for:

[0196] If the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is greater than or equal to the third preset threshold, then the value of the preset total heat transfer coefficient is set to the value of the predicted total heat transfer coefficient, and the step of obtaining the first heat exchange based on the preset total heat transfer coefficient is re-executed.

[0197] In some embodiments, the micro-element segment verification module 403 is specifically used for:

[0198] The predicted overall heat transfer coefficient can be obtained using the following formula:

[0199]

[0200] Among them, K c To predict the overall heat transfer coefficient, d o Let d be the outer diameter of the heat exchange tube. i h is the inner diameter of the heat exchange tube. o h is the initial external heat transfer coefficient. i R is the initial heat transfer coefficient inside the tube. i To reduce the thermal resistance of fouling on the inner wall of the pipe, R w R is the thermal resistance of the pipe wall. o For the thermal resistance of fouling on the outer wall of the pipe, d m This represents the average diameter of the heat exchange tubes.

[0201] In some embodiments, prior to the step of obtaining the structural parameters of the heat exchanger tube based on the pre-designed heat exchange area, the preliminary design module 401 is further configured to:

[0202] The heat exchange area is obtained based on the preset heat load.

[0203] It is understood that the heat exchange system verification device of the submerged combustion gasifier in this application embodiment can divide the heat exchange tube into several micro-segments along the path and perform iterative processing on each micro-segment based on thermal balance. This allows for more accurate acquisition of the heat exchange heat, temperature field and heat transfer coefficient of the heat exchange tube, making the verification process more consistent with actual working conditions, more reliable, and also conducive to improving design efficiency.

[0204] The above provides a detailed description of the heat exchange system verification method and apparatus for a submerged combustion gasifier provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for verifying the heat exchange system of a submerged combustion gasifier, characterized in that, The heat exchange system includes heat exchange tubes; the method includes: The structural parameters of the heat exchange tube are obtained based on the pre-designed heat exchange area; Along the extension direction of the heat exchange tube, the model of the heat exchange tube is meshed to obtain multiple micro-segments; Based on the structural parameters, the temperature parameters of each micro-segment and the total heat transfer coefficient of each micro-segment are obtained. The temperature parameters include the actual outlet temperature and the actual inner wall temperature. If the temperature parameters and overall heat transfer coefficient of each micro-segment do not meet the current design conditions, the heat exchange area is adjusted, and the structural parameters of the heat exchange tube are re-obtained based on the adjusted heat exchange area. If the temperature parameters and total heat transfer coefficient of each of the micro-segments meet the current design conditions, then the structural parameters, the heat exchange area, and the total heat transfer coefficient of each of the micro-segments are determined as the target parameters of the heat exchange tube. The step of obtaining the temperature parameters of each micro-segment includes: For any of the aforementioned micro-segments, the first heat exchange is obtained based on the preset total heat transfer coefficient; Based on the preset outlet temperature and inlet temperature of the micro-element segment, the inlet and outlet enthalpy difference is obtained. The second heat exchange is obtained based on the inlet and outlet enthalpy difference; If the relative error between the first heat exchanger and the second heat exchanger is less than the first preset threshold, then the preset outlet temperature is determined as the actual outlet temperature of the micro-element segment. Based on the preset inner wall temperature of the micro-segment, the average temperature of the micro-segment, the inner wall area of ​​the micro-segment, and the initial heat transfer coefficient inside the tube, the third heat exchange of the micro-segment is obtained, and the average temperature is the average of the inlet temperature and the actual outlet temperature. The fourth heat exchange of the micro-element segment is obtained based on the outer wall temperature, water bath temperature, outer wall area, and initial external heat transfer coefficient of the micro-element segment. If the error between the third heat exchange and the fourth heat exchange is less than the second preset threshold, then the preset inner wall temperature is determined as the actual inner wall temperature of the micro-element segment.

2. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, The method further includes: If the relative error between the first heat exchange and the second heat exchange is greater than or equal to the first preset threshold, then the predicted outlet temperature of the micro-element segment is obtained. Set the preset outlet temperature of the micro-segment to the predicted outlet temperature, and re-execute the step of obtaining the first heat exchange based on the preset total heat transfer coefficient.

3. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, The process of obtaining the first heat exchange based on a preset total heat transfer coefficient includes: The first heat exchange capacity is obtained using the following formula: Where Q1 is the first heat exchanger, K i Let A be the preset overall heat transfer coefficient. i Let Δt be the inner wall area of ​​the infinitesimal segment. mi The logarithmic mean temperature difference of the micro-element segment.

4. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, Based on the aforementioned inlet and outlet enthalpy difference, the second heat exchange is obtained, including: The second heat exchange capacity is obtained using the following formula: Where Q2 is the second heat exchanger, q m This represents the mass flow rate of the fluid inside the pipe. The enthalpy of the exit of the micro-element segment. Let t be the inlet enthalpy of the micro-element segment. i+1 t is the preset outlet temperature. i The inlet temperature is [value].

5. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, The method further includes: If the error between the third heat exchanger and the fourth heat exchanger is greater than or equal to the second preset threshold, then the predicted inner wall temperature of the micro-element segment is obtained. Set the preset inner wall temperature of the micro-element segment to the predicted inner wall temperature, and re-execute the step of obtaining the third heat exchange of the micro-element segment based on the preset inner wall temperature of the micro-element segment, the average temperature of the micro-element segment, the inner wall area of ​​the micro-element segment, and the initial heat transfer coefficient inside the pipe.

6. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, Based on the preset inner wall temperature of the micro-element segment, the average temperature of the micro-element segment, the inner wall area of ​​the micro-element segment, and the initial heat transfer coefficient inside the tube, the third heat exchange capacity of the micro-element segment is obtained, including: The third heat exchanger is obtained using the following formula: Among them, Q i For the third heat exchange, h i Let A be the initial heat transfer coefficient inside the tube. i t is the inner wall area of ​​the infinitesimal segment. wi t is the preset inner wall temperature of the micro-element segment. f The inlet and outlet average temperature of the micro-element segment.

7. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, Based on the outer wall temperature, water bath temperature, outer wall area, and initial external heat transfer coefficient of the micro-element segment, the fourth heat exchange capacity of the micro-element segment is obtained, including: The fourth heat exchanger is obtained using the following formula: Among them, Q o For the fourth heat exchange, h o Let A be the initial external heat transfer coefficient. o t is the area of ​​the outer wall. wo t is the outer wall temperature of the micro-element segment. w The water bath temperature is [value missing].

8. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, Obtaining the total heat transfer coefficient of each of the micro-segments includes: Based on the fouling thermal resistance of the inner wall of the tube, the fouling thermal resistance of the outer wall of the tube, the tube wall thermal resistance, the inner and outer tube diameters, the initial heat transfer coefficient inside the tube, and the initial heat transfer coefficient outside the tube of the micro-segment, the predicted total heat transfer coefficient is obtained. If the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is less than a third preset threshold, then the preset total heat transfer coefficient is determined as the actual total heat transfer coefficient of the micro-element.

9. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 8, characterized in that, The method further includes: If the error between the predicted total heat transfer coefficient and the preset total heat transfer coefficient is greater than or equal to the third preset threshold, then the value of the preset total heat transfer coefficient is set to the value of the predicted total heat transfer coefficient, and the step of obtaining the first heat exchange based on the preset total heat transfer coefficient is re-executed.

10. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 8, characterized in that, Based on the fouling thermal resistance of the inner wall of the tube, the fouling thermal resistance of the outer wall of the tube, the tube wall thermal resistance, the inner and outer tube diameters, the initial inner tube heat transfer coefficient, and the initial outer tube heat transfer coefficient of the tube segment, the predicted total heat transfer coefficient is obtained, including: The predicted overall heat transfer coefficient is obtained using the following formula: Among them, K c Let d be the predicted total heat transfer coefficient. o Let d be the outer diameter of the heat exchange tube. i h is the inner diameter of the heat exchange tube. o Let h be the initial external heat transfer coefficient. i R is the initial heat transfer coefficient inside the tube. i R is the thermal resistance of the fouling on the inner wall of the pipe. w R is the thermal resistance of the tube wall. o d represents the thermal resistance of the fouling on the outer wall of the pipe. m The average diameter of the heat exchange tube is given.

11. The method for verifying the heat exchange system of a submerged combustion gasifier according to claim 1, characterized in that, Prior to the step of obtaining the structural parameters of the heat exchanger tube based on the pre-designed heat exchange area, the method further includes: The heat exchange area is obtained based on the preset heat load.

12. A verification device for the heat exchange system of a submerged combustion gasifier, characterized in that, The heat exchange system includes heat exchange tubes; the device includes: The preliminary design module is used to obtain the structural parameters of the heat exchange tube based on the pre-designed heat exchange area; The differential processing module is used to perform meshing processing on the model of the heat exchange tube along the extension direction of the heat exchange tube to obtain multiple micro-segments; The micro-segment verification module is used to obtain the temperature parameters of each micro-segment based on the structural parameters, and to obtain the total heat transfer coefficient of each micro-segment. The temperature parameters include the actual outlet temperature and the actual inner wall temperature. The verification and confirmation module is used to adjust the heat exchange area if the temperature parameters and total heat transfer coefficient of each micro-segment do not meet the current design conditions, and to re-obtain the structural parameters of the heat exchange tube based on the adjusted heat exchange area. The verification and confirmation module is further configured to determine the structural parameters, the heat exchange area, and the total heat transfer coefficient of each micro-segment as the target parameters of the heat exchange tube if the temperature parameters and total heat transfer coefficient of each micro-segment meet the current design conditions. Specifically, the micro-element segment verification module is used for: For any of the aforementioned micro-segments, the first heat exchange is obtained based on the preset total heat transfer coefficient; Based on the preset outlet temperature and inlet temperature of the micro-element segment, the inlet and outlet enthalpy difference is obtained. The second heat exchange is obtained based on the inlet and outlet enthalpy difference; If the relative error between the first heat exchanger and the second heat exchanger is less than the first preset threshold, then the preset outlet temperature is determined as the actual outlet temperature of the micro-element segment. Based on the preset inner wall temperature of the micro-segment, the average temperature of the micro-segment, the inner wall area of ​​the micro-segment, and the initial heat transfer coefficient inside the tube, the third heat exchange of the micro-segment is obtained, and the average temperature is the average of the inlet temperature and the actual outlet temperature. The fourth heat exchange of the micro-element segment is obtained based on the outer wall temperature, water bath temperature, outer wall area, and initial external heat transfer coefficient of the micro-element segment. If the error between the third heat exchange and the fourth heat exchange is less than the second preset threshold, then the preset inner wall temperature is determined as the actual inner wall temperature of the micro-element segment.

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