Modelica language-based multi-stream heat exchanger pinch point design and modeling method and device

Abstract

The invention belongs to the technical field of modeling simulation, and relates to a Modelica language-based multi-stream heat exchanger pinch point design and modeling method and device, and the method comprises the steps: constructing a multi-stream heat exchanger model based on a Modelica language, and achieving the dynamic coupling of a heat exchange system through modular design, the method at least comprises the steps of stream compounding and initial configuration, enthalpy interval segmentation and multi-balance coupling model establishment, segmentation discrete model establishment, simulation system construction and performance verification. The method provided by the invention is based on a multi-balance coupling modeling framework of a Modelica language, breaks through static assumption and fixed physical property limitation of a traditional method through composite flow stream temperature enthalpy line cross analysis, CoolProp physical property library real-time calling and segmented discrete dynamic optimization, realizes cooperative calculation of pinch point positions, minimum heat transfer temperature differences and heat exchange areas, and improves the calculation efficiency. And a design basis of thermodynamic consistency is provided for a complex industrial scene.

Description

Technical Field

[0001] The present invention belongs to the technical field of modeling and simulation, and relates to a multi-stream heat exchanger pinch point design and modeling method, and in particular to a multi-stream heat exchanger pinch point design and modeling method and device based on Modelica language. Background Art

[0002] As core equipment for energy integration, multi-stream heat exchangers are widely used in fields such as liquefied natural gas (LNG) production, air separation, supercritical carbon dioxide (sCO2) power cycles, and chemical complexes. For example, in the LNG production process, multi-stream heat exchangers need to simultaneously handle the phase change heat transfer of multi-component refrigerants such as methane and ethane, achieving cascaded utilization of cold energy to reduce energy consumption. In air separation units, they efficiently recover the low-temperature waste heat of nitrogen and oxygen through a countercurrent / crosscurrent mixing flow channel layout, improving the system's thermodynamic efficiency. In advanced energy systems such as the Allam cycle, multi-stream heat exchangers need to cope with the high-pressure and high-temperature heat transfer of supercritical CO2 and the energy integration of multiphase mixed streams. In addition, in chemical complexes, multi-stream heat exchangers can integrate the heat exchange of multiple streams, reducing equipment footprint and optimizing investment costs.

[0003] Currently, existing methods often simplify multiple streams into equivalent cold / hot composite curves with constant heat capacity flow rates, ignoring the dynamic heat exchange and phase change properties of the multiple streams. For example, in the LNG liquefaction process, the phase change temperature range and heat capacity flow rate of the methane-ethane mixed refrigerant vary dramatically. Traditional composite curve methods can easily lead to misjudgment of pinch point locations, resulting in reduced cold energy recovery. Furthermore, in sCO2 heat exchangers, the nonlinear properties of supercritical fluids cause heat capacity flow rates to fluctuate dramatically with temperature. Pinch point analysis based on the assumption of constant heat capacity is prone to redundant heat exchange areas and misjudgment of pinch point locations.

[0004] It can be seen from this that how to provide a pinch point design and modeling method for multi-stream heat exchangers, break through the static assumptions and physical property limitations of traditional methods, and realize the coordinated calculation of pinch point position, minimum heat transfer temperature difference and heat exchange area has become an urgent problem to be solved by technical personnel in this field. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a multi-stream heat exchanger pinch point design and modeling method and device based on the Modelica language, breaking through the static assumptions and fixed physical property limitations of traditional methods, realizing the coordinated calculation of pinch point position, minimum heat transfer temperature difference and heat exchange area, and providing a thermodynamically consistent design benchmark for complex industrial scenarios.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a multi-stream heat exchanger pinch point design and modeling method based on the Modelica language. The method constructs a multi-stream heat exchanger model based on the Modelica language and uses a modular design to achieve dynamic coupling of the heat exchange system. The method includes at least the following steps:

[0008] S1 Stream Recombination and Initial Configuration: Set the isothermal section based on the inlet and outlet temperatures of each stream, recombining the hot and cold streams separately. Delimit the temperature range through cross-analysis of the composite temperature enthalpy lines of the hot and cold streams to achieve the initial configuration of the heat recovery path.

[0009] S2 enthalpy interval segmentation and multi-equilibrium coupling model establishment: The enthalpy interval of the multi-stream heat exchanger is segmented according to the inflection point. The CoolProp physical property library is called to obtain phase change parameters and thermophysical property data. Based on the energy balance equation, mass conservation equation, and momentum conservation equation, a multi-equilibrium coupling model is established to describe the interaction behavior of the streams.

[0010] S3: Establish a piecewise discrete model: Discrete the heat exchange section into n heat exchange units, establish a piecewise discrete model, calculate the internal temperature field of the entire multi-stream heat exchanger, and determine the pinch point of the heat exchange process and the heat exchanger efficiency;

[0011] S4 simulation system construction and performance verification: Based on the segmented discrete model of the multi-stream heat exchanger and combined with the actual design conditions, a pinch point analysis simulation system for the multi-stream heat exchanger was constructed. The heat transfer area, outlet temperature, internal pinch point location, and minimum heat transfer temperature difference of the multi-stream heat exchanger were analyzed to verify the system performance and response characteristics.

[0012] In the second aspect, the present invention provides a multi-stream heat exchanger pinch point design and modeling device based on the Modelica language. The device constructs a multi-stream heat exchanger model based on the Modelica language, and adopts a modular design to realize the dynamic coupling of the heat exchange system. It at least includes: a stream compound and initial configuration module, an enthalpy interval segmentation and multi-equilibrium coupling model establishment module, a segmented discrete model establishment module, and a simulation system construction and performance verification module.

[0013] In a third aspect, the present invention provides an electronic device, comprising:

[0014] at least one processor; and

[0015] a memory communicatively connected to the at least one processor; wherein,

[0016] The memory stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language described in the first aspect.

[0017] In a fourth aspect, the present invention provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language described in the first aspect when executed.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The method provided by the present invention utilizes the law of conservation of energy to simulate the energy transfer process inside a multi-stream heat exchanger, constructs a multi-stream heat exchanger model based on the Modelica language, and adopts a modular design to realize the dynamic coupling of the heat exchange system. Data is input through a multi-stream input interface, and the model can output key parameters including the temperature-enthalpy change path inside the heat exchanger, the outlet temperature of each stream, pressure, heat exchange area, and internal pinch point temperature difference. The constructed multi-stream heat exchanger model realizes high-precision simulation across flow states. The model is particularly aimed at the physical property changes and pinch point judgment problems of the multi-component sCO2 regenerator in the Allam cycle, and uses the CoolProp physical property library to support thermal integration optimization containing phase change between multiple streams. This modular architecture can adapt to different working fluid combinations and complex process configurations, and is suitable for the design and performance optimization of compact multi-stream heat exchangers in energy systems.

[0020] (2) The multi-stream heat exchanger pinch point design model established in the present invention has a unified modeling specification, good scalability, and high reusability, which provides support for future research on multi-stream heat exchangers. At the same time, the Modelica language is used to accurately simulate the energy transfer process inside the multi-stream heat exchanger based on the discrete method, ensuring the accuracy of pinch point judgment of the multi-stream heat exchanger under a large range of state parameter changes, and effectively solving the problem of misjudgment of pinch point position in complex working conditions by traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the multi-stream heat exchanger pinch point design and modeling method based on Modelica language provided by the present invention;

[0022] Figure 2 1 is an overall schematic diagram of a multi-stream heat exchanger model in the method provided by the present invention;

[0023] Figure 3 Schematic diagram of a multi-stream heat exchanger test model in the method provided by the present invention;

[0024] Figure 4 The method provided by the present invention is used to determine the temperature-enthalpy diagram of the internal pinch point of a multi-stream heat exchanger;

[0025] Figure 5It is a structural schematic diagram of a multi-stream heat exchanger pinch point design and modeling device based on Modelica language provided by the present invention;

[0026] Figure 6 It is a schematic diagram of the structure of an electronic device provided by the present invention for implementing the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0028] An embodiment of the present invention provides a multi-stream heat exchanger pinch point design and modeling method based on the Modelica language. The method constructs a multi-stream heat exchanger model based on the Modelica language and adopts a modular design to realize the dynamic coupling of the heat exchange system. Figure 1 As shown, the method comprises at least the following steps:

[0029] S1 Stream Recombination and Initial Configuration: Set the isothermal section based on the inlet and outlet temperatures of each stream, recombining the hot and cold streams separately. Delimit the temperature range through cross-analysis of the composite temperature enthalpy lines of the hot and cold streams to achieve the initial configuration of the heat recovery path.

[0030] S2 enthalpy interval segmentation and multi-equilibrium coupling model establishment: The enthalpy interval of the multi-stream heat exchanger is segmented according to the inflection point. The CoolProp physical property library is called to obtain phase change parameters and thermophysical property data. Based on the energy balance equation, mass conservation equation, and momentum conservation equation, a multi-equilibrium coupling model is established to describe the interaction behavior of the streams.

[0031] S3: Establish a piecewise discrete model: Discrete the heat exchange section into n heat exchange units, establish a piecewise discrete model, calculate the internal temperature field of the entire multi-stream heat exchanger, and determine the pinch point of the heat exchange process and the heat exchanger efficiency;

[0032] S4 simulation system construction and performance verification: Based on the segmented discrete model of the multi-stream heat exchanger and combined with the actual design conditions, a pinch point analysis simulation system for the multi-stream heat exchanger was constructed. The heat transfer area, outlet temperature, internal pinch point location, and minimum heat transfer temperature difference of the multi-stream heat exchanger were analyzed to verify the system performance and response characteristics.

[0033] Since the Mworks.Sysplorer software supports the general simulation language Modelica, some embodiments provide processes implemented in the Mworks.Sysplorer software. It should be noted that the method provided by the present invention can be implemented in other simulation software that supports the Modelica language.

[0034] In addition, the CoolProp physical property library used in the present invention is an open source physical property database and calculation library that can provide thermal physical property data of a variety of fluids, including temperature, pressure, specific enthalpy, specific entropy, etc., and in heat exchanger modeling, CoolProp is used to calculate the temperature of the fluid based on the known pressure and specific enthalpy, so that the model can update the state of the fluid in real time and adapt to complex working conditions.

[0035] Example 1

[0036] This embodiment provides a multi-stream heat exchanger pinch point design and modeling method based on the Modelica language. The method is implemented in the Mworks.Sysplorer software and is divided into the following steps:

[0037] (1) The isothermal section is set according to the inlet and outlet temperatures of each stream, and the hot and cold streams are compounded respectively. The temperature range is demarcated by cross-analysis of the composite temperature enthalpy lines of the hot and cold streams to achieve the initial configuration of the heat recovery path. The record of stream compounding adopts the records structure in the Modelica language.

[0038] (2) The enthalpy interval of the multi-stream heat exchanger is segmented according to the inflection point. The CoolProp physical property library is called to obtain phase change parameters and thermophysical property data. A multi-equilibrium coupling model is established based on the energy balance equation, mass conservation equation, and momentum conservation equation to describe the flow interaction behavior, including:

[0039] (2.1) Heat matching determination and heat exchange distribution:

[0040] In the isothermal section, the smaller value of the exchangeable heat of the cold and hot streams is taken as the actual heat exchange rate. The calculation formula is:

[0041] Q=min(deltaQ_c,deltaQ_h)

[0042] Where Q is the actual heat exchange rate; deltaQ_c and deltaQ_h are the heat capacity load differences of the cold and hot streams, respectively.

[0043] (2.2) Dynamic update of temperature field:

[0044] Based on the CoolProp physical property library, the outlet temperatures of the hot and cold streams are calculated separately using the following formula:

[0045] T co =T_Ph(P co ,H co )

[0046] T ho =T_Ph(P ho ,H ho )

[0047] Among them, T co 、T ho are the outlet temperatures of the cold and hot streams based on the actual heat exchange capacity; P co 、P ho are the pressures of the cold and hot streams respectively; H co 、H ho are the outlet specific enthalpies of the cold and hot streams based on the actual heat exchange capacity, respectively.

[0048] (2.3) Flow status progressive strategy:

[0049] When the heat exchange capacity of the cold stream is completely exhausted, the cold stream is removed (incrementing the cold stream index) and the outlet temperature of the hot stream is checked to see if it exceeds the design threshold. If so, the residual heat of the hot stream is retained; otherwise, the hot stream is switched synchronously.

[0050] When the heat exchange capacity of the hot stream is completely exhausted, the hot stream is removed (incrementing the heat stream index) and the outlet temperature of the cold stream is checked to see if it exceeds the design threshold. If so, the residual heat of the cold stream is retained; otherwise, the cold stream is switched synchronously.

[0051] (3) The heat exchange section is discretized into n heat exchange units, and a segmented discrete model is established. The heat exchange capacity of a single heat exchange unit is multiplied by n to obtain the heat exchange capacity of the entire heat exchange section. The pinch point position and the minimum heat transfer temperature difference are determined in combination with the thermal threshold constraint.

[0052] Because multiple fluids are simultaneously exchanging heat in a multi-stream heat exchanger, a segmented method is used to accurately describe the complex heat exchange process. The hot and cold fluids can be divided into many small intervals according to their flow direction. Within each interval, the fluid properties are set to constant values, and the temperature difference between the hot and cold fluids must not be less than the minimum allowable heat exchange temperature difference. The specific calculation process includes the following:

[0053] (3.1) The logarithmic mean temperature difference heat transfer calculation, the relevant formula is:

[0054] Q=UA×LMTD

[0055] Where Q is the logarithmic mean temperature difference heat transfer; U and A are the heat transfer coefficient and heat transfer area, respectively; LMTD is the logarithmic mean temperature difference, which represents the heat transfer rate.

[0056] Given the rapid changes in CO2's thermodynamic properties, the pinch point of a heat exchanger may not occur at the inlet or outlet. To accurately describe the heat transfer process, the heat exchanger is segmented. Within each segment, the CO2 properties are assumed to remain constant, allowing for the LMTD to be calculated for each segment. A converged calculation must ensure that the LMTD of all discrete elements in the pinch temperature difference is greater than the minimum pinch temperature difference.

[0057] (3.2) Calculation of heat transfer between hot and cold streams:

[0058]

[0059] in, is the heat transfer of hot and cold streams; CP c i 、CP h i are the heat capacity flow rates of the composite flow of the hot and cold sections of the i-th heat exchange unit; are the inlet and outlet temperatures of the composite flow of the hot and cold sections of the i-th heat exchange unit respectively.

[0060] (3.3) The logarithmic mean temperature difference of the i-th heat exchange unit is calculated using the following formula:

[0061] LMTD k =(ΔT max -ΔT min ) / ln(ΔT max / ΔT min )

[0062] Among them, LMTD k is the logarithmic mean temperature difference of the i-th heat exchange unit; ΔT max is the maximum temperature difference between the inlet and outlet of the cold and hot sections of the i-th heat exchange unit, ΔT min The minimum temperature difference between the inlet and outlet cold and hot streams of the hot and cold section composite flow of the i-th heat exchange unit.

[0063] (3.4) Calculation of design parameters of each section of the heat exchanger. The relevant formula is:

[0064]

[0065] Among them, U and A are heat transfer coefficient and heat transfer area respectively; is the heat transfer of the hot and cold streams; LMTD k is the logarithmic mean temperature difference of the i-th heat exchange unit.

[0066] (4) Based on the component-level model, a nitrogen regulator simulation system is built according to the actual physical topology and operating conditions of the nitrogen regulator, and the interface of the nitrogen regulator to the outside world and the interface for data transmission between its components are determined.

[0067] Specifically, the data transmission interface between the component-level models of the multi-stream heat exchanger and between the components and the outside world is determined. According to the actual physical topology of the multi-stream heat exchanger, the data exchanged between the components includes the heat exchange between the streams, and the data exchanged with the outside world includes the fluid exchange and heat exchange between the multi-stream heat exchanger and the outside world. The model library interface is shown in Table 1 below.

[0068] Table 1

[0069]

[0070] like Figure 2 As shown in Figure 2, a simulation model of a multi-stream heat exchanger is constructed based on the design and operating conditions of the multi-stream heat exchanger. The parameter information of the streams in the multi-stream heat exchanger is shown in Table 2 below.

[0071] Table 2

[0072] Stream name Inlet temperature / ℃ Inlet temperature / ℃ Inlet pressure / kpa Mass flow rate / kg / s Hot flow stock 1 Lack of airflow 741.18 62.12 3400 1370.4 Hot flow 2 Air separation flow 270.00 62.12 750 276.3 Cold flow stock 1 Blade cooling flow 54.17 184.00 30500 99.0 Cold flow stock 2 Oxidation Flow 47.03 721.18 30500 612.6 Cold flow stock 3 CO2 circulation flow 54.17 721.18 30500 641.9

[0073] like Figure 3 As shown in the figure, a test model system of a multi-stream heat exchanger is built.

[0074] For example, in this embodiment Figure 2 and Figure 3 The interface names are distinguished by the downstream devices of each stream. The names of each interface can be customized according to its specific purpose.

[0075] After the simulation system is built, Figure 4 The heat transfer enthalpy diagram shows that the simulation system can well simulate the internal pinch point position and temperature difference of the multi-stream heat exchanger and derive the design parameters of each corresponding heat exchange section.

[0076] Example 2

[0077] This embodiment provides a multi-stream heat exchanger pinch point design and modeling device based on Modelica language. The device constructs a multi-stream heat exchanger model based on Modelica language and adopts modular design to realize dynamic coupling of heat exchange system. Figure 5 As shown, the device includes: a stream combination and initial configuration module 201, an enthalpy interval segmentation and multi-equilibrium coupling model establishment module 202, a segmented discrete model establishment module 203, and a simulation system construction and performance verification module 204.

[0078] The stream compounding and initial configuration module 201 is used to set the isothermal section according to the inlet and outlet temperatures of each stream, compound the hot and cold streams respectively, and define the temperature range by cross-analysis of the composite temperature enthalpy lines of the hot and cold streams to achieve the initial configuration of the heat recovery path.

[0079] The enthalpy interval segmentation and multi-equilibrium coupling model establishment module 202 is used to segment the enthalpy interval of the multi-stream heat exchanger according to the inflection point, call the CoolProp physical property library to obtain phase change parameters and thermal physical property data, and establish a multi-equilibrium coupling model based on the energy balance equation, mass conservation equation and momentum conservation equation to describe the flow interaction behavior.

[0080] The segmented discrete model building module 203 is used to discretize the interior of the heat exchange section into n heat exchange units, establish a segmented discrete model, calculate the internal temperature field of the entire multi-stream heat exchanger, and determine the pinch point of the heat exchange process and the heat exchanger efficiency.

[0081] The simulation system construction and performance verification module 204 is used to construct a pinch point analysis simulation system for the multi-stream heat exchanger based on the segmented discrete model of the multi-stream heat exchanger in combination with the actual design working conditions, analyze the heat transfer area of the multi-stream heat exchanger, the outlet temperature of the multi-stream heat exchanger, the location of the internal pinch point and the minimum heat transfer temperature difference, and verify the system performance and response characteristics.

[0082] In the stream composition and initial configuration module 201 , the stream composition record adopts the records structure in the Modelica language.

[0083] In the enthalpy interval segmentation and multi-equilibrium coupling model establishment module 202, the enthalpy interval segmentation calculation method includes at least the following steps:

[0084] S2.1 Heat matching determination and heat exchange distribution: In the isothermal section, the smaller of the exchangeable heat of the hot and cold streams is taken as the actual heat exchange. The calculation formula is:

[0085] Q=min(deltaQ_c,deltaQ_h)

[0086] Where Q is the actual heat exchange rate; deltaQ_c and deltaQ_h are the heat capacity load differences of the cold and hot streams, respectively.

[0087] S2.2 Dynamic update of temperature field: Based on the CoolProp physical property library, the outlet temperatures of the hot and cold streams are calculated respectively. The calculation formula is:

[0088] T co =T_Ph(P co ,H co )

[0089] T ho =T_Ph(P ho ,H ho )

[0090] Among them, T co 、T ho are the outlet temperatures of the cold and hot streams based on the actual heat exchange capacity; P co 、P ho are the pressures of the cold and hot streams respectively; H co 、H ho are the outlet specific enthalpies of the cold and hot streams based on the actual heat exchange capacity, respectively.

[0091] S2.3 Stream status progressive strategy: When the heat exchange capacity of the cold stream is completely exhausted, the cold stream is removed and the outlet temperature of the hot stream is checked to see if it exceeds the design threshold. If so, the residual heat of the hot stream is retained, otherwise the hot stream is switched synchronously; when the heat exchange capacity of the hot stream is completely exhausted, the hot stream is removed and the outlet temperature of the cold stream is checked to see if it exceeds the design threshold. If so, the residual heat of the cold stream is retained, otherwise the cold stream is switched synchronously.

[0092] In the segmented discrete model building module 203, the calculation of the internal temperature field of the entire multi-stream heat exchanger includes at least: multiplying the heat exchange rate of a single heat exchange unit by n, that is, the heat exchange rate of the entire heat exchange section, and determining the pinch point position and the minimum heat transfer temperature difference in combination with the thermal threshold constraint.

[0093] In addition, the determination of the pinch point of the heat exchange process and the heat exchanger efficiency includes at least the following calculation process:

[0094] S3.1 Calculation of heat transfer by logarithmic mean temperature difference. The relevant formula is:

[0095] Q=UA×LMTD

[0096] Where Q is the logarithmic mean temperature difference heat transfer; U and A are the heat transfer coefficient and heat transfer area, respectively; LMTD is the logarithmic mean temperature difference, which represents the heat transfer rate.

[0097] S3.2 Calculation of heat transfer between hot and cold streams. The relevant formula is:

[0098]

[0099] in, is the heat transfer of hot and cold streams; CP c i 、CP h i are the heat capacity flow rates of the composite flow of the hot and cold sections of the i-th heat exchange unit; are the inlet and outlet temperatures of the composite flow of the hot and cold sections of the i-th heat exchange unit respectively.

[0100] S3.3 Calculation of the logarithmic mean temperature difference of the i-th heat exchange unit. The relevant formula is:

[0101] LMTD k =(ΔT max -ΔT min ) / ln(ΔT max / ΔT min )

[0102] Among them, LMTD k is the logarithmic mean temperature difference of the i-th heat exchange unit; ΔT max is the maximum temperature difference between the inlet and outlet of the cold and hot sections of the i-th heat exchange unit, ΔTmin The minimum temperature difference between the inlet and outlet cold and hot streams of the hot and cold section composite flow of the i-th heat exchange unit.

[0103] S3.4 Calculation of design parameters of each section of the heat exchanger. The relevant formula is:

[0104]

[0105] Among them, U and A are heat transfer coefficient and heat transfer area respectively; is the heat transfer of the hot and cold streams; LMTD k is the logarithmic mean temperature difference of the i-th heat exchange unit.

[0106] The device provided in this embodiment can execute the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0107] Example 3

[0108] This embodiment provides an electronic device for implementing a multi-stream heat exchanger pinch point design and modeling method based on the Modelica language, such as Figure 6 As shown, the electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital assistants, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present application described and / or required herein.

[0109] like Figure 6 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., which is communicatively connected to the at least one processor 11. The memory stores a computer program that can be executed by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. Various programs and data required for the operation of the electronic device 10 can also be stored in the RAM 13. The processor 11, ROM 12, and RAM 13 are connected to each other via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0110] Multiple components in the electronic device 10 are connected to the I / O interface 15, including an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a second storage area, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0111] Processor 11 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 11 executes the various methods and processes described above, such as the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language.

[0112] In some embodiments, the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language by any other appropriate means (e.g., by means of firmware).

[0113] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-chip systems (SOCs), programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0114] Computer programs for implementing the methods of the present application can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable target-determining device, so that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0115] In the context of the present application, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. A computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. A more specific example of a machine-readable storage medium can include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0116] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0117] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0118] A computing system may include clients and servers. The clients and servers are typically remote from each other and typically interact via a communication network. This client-server relationship arises through computer programs running on the respective computers, creating a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host. This server is a hosting product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosting and VPS services.

[0119] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this application can be performed in parallel, sequentially, or in a different order, as long as the desired information of the technical solution of this application can be achieved. This document is not limited here.

[0120] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A multi-stream heat exchanger pinch point design and modeling method based on Modelica language, characterized in that: The method constructs a multi-stream heat exchanger model based on the Modelica language and uses a modular design to realize dynamic coupling of the heat exchange system, and includes at least the following steps: S1 Stream Recombination and Initial Configuration: Set the isothermal section based on the inlet and outlet temperatures of each stream, recombining the hot and cold streams separately. Delimit the temperature range through cross-analysis of the composite temperature enthalpy lines of the hot and cold streams to achieve the initial configuration of the heat recovery path. S2 enthalpy interval segmentation and multi-equilibrium coupling model establishment: The enthalpy interval of the multi-stream heat exchanger is segmented according to the inflection point. The CoolProp physical property library is called to obtain phase change parameters and thermophysical property data. Based on the energy balance equation, mass conservation equation, and momentum conservation equation, a multi-equilibrium coupling model is established to describe the interaction behavior of the streams. S3: Establish a piecewise discrete model: Discrete the heat exchange section into n heat exchange units, establish a piecewise discrete model, calculate the internal temperature field of the entire multi-stream heat exchanger, and determine the pinch point of the heat exchange process and the heat exchanger efficiency; S4 simulation system construction and performance verification: Based on the segmented discrete model of the multi-stream heat exchanger and combined with the actual design conditions, a pinch point analysis simulation system for the multi-stream heat exchanger was constructed. The heat transfer area, outlet temperature, internal pinch point location, and minimum heat transfer temperature difference of the multi-stream heat exchanger were analyzed to verify the system performance and response characteristics.

2. The multi-stream heat exchanger pinch point design and modeling method based on Modelica language according to claim 1 is characterized in that: The record of the stream compound described in step S1 adopts the records structure in the Modelica language.

3. The multi-stream heat exchanger pinch point design and modeling method based on Modelica language according to claim 1 is characterized in that: The calculation method of the enthalpy interval segmentation described in step S2 at least includes the following steps: S2.1 Heat matching determination and heat exchange distribution: In the isothermal section, the smaller of the exchangeable heat of the hot and cold streams is taken as the actual heat exchange. The calculation formula is: Q=min(deltaQ_c,deltaQ_h) Where Q is the actual heat exchange; deltaQ_c and deltaQ_h are the heat capacity load differences of the cold and hot streams respectively; S2.2 Dynamic update of temperature field: Based on the CoolProp physical property library, the outlet temperatures of the hot and cold streams are calculated respectively. The calculation formula is: T co =T_Ph(P co ,H co ) T ho =T_Ph(P ho ,H ho ) Among them, T co 、T ho are the outlet temperatures of the cold and hot streams based on the actual heat exchange capacity; P co 、P ho are the pressures of the cold and hot streams respectively; H co 、H ho are the outlet specific enthalpies of the cold and hot streams based on the actual heat exchange capacity, respectively; S2.3 Stream status progressive strategy: When the heat exchange capacity of the cold stream is completely exhausted, the cold stream is removed and the outlet temperature of the hot stream is checked to see if it exceeds the design threshold. If so, the residual heat of the hot stream is retained, otherwise the hot stream is switched synchronously; when the heat exchange capacity of the hot stream is completely exhausted, the hot stream is removed and the outlet temperature of the cold stream is checked to see if it exceeds the design threshold. If so, the residual heat of the cold stream is retained, otherwise the cold stream is switched synchronously.

4. The multi-stream heat exchanger pinch point design and modeling method based on Modelica language according to claim 1 is characterized in that: Calculating the internal temperature field of the entire multi-stream heat exchanger in step S3 at least includes: multiplying the heat exchange capacity of a single heat exchange unit by n, which is the heat exchange capacity of the entire heat exchange section, and determining the pinch point position and the minimum heat transfer temperature difference in combination with the thermal threshold constraint.

5. The multi-stream heat exchanger pinch point design and modeling method based on Modelica language according to claim 4 is characterized in that: Determining the pinch point of the heat exchange process and the heat exchanger efficiency in step S3 includes at least the following calculation process: S3.1 Calculation of heat transfer by logarithmic mean temperature difference. The relevant formula is: Q=UA×LMTD Where Q is the heat transfer rate of the logarithmic mean temperature difference; U and A are the heat transfer coefficient and heat transfer area respectively; LMTD is the logarithmic mean temperature difference, which represents the heat transfer rate; S3.2 Calculation of heat transfer between hot and cold streams. The relevant formula is: in, is the heat transfer of hot and cold streams; CP c i 、CP h i are the heat capacity flow rates of the composite flow of the hot and cold sections of the i-th heat exchange unit; are the inlet and outlet temperatures of the composite flow of the hot and cold sections of the i-th heat exchange unit respectively; S3.3 Calculation of the logarithmic mean temperature difference of the i-th heat exchange unit. The relevant formula is: LMTD k =(ΔT max -ΔT min ) / ln(ΔT max / ΔT min ) Among them, LMTD k is the logarithmic mean temperature difference of the i-th heat exchange unit; ΔT max is the maximum temperature difference between the inlet and outlet of the cold and hot sections of the i-th heat exchange unit, ΔT min is the minimum temperature difference between the inlet and outlet cold and hot streams of the hot and cold section composite flow of the i-th heat exchange unit; S3.4 Calculation of design parameters of each section of the heat exchanger. The relevant formula is: Among them, U and A are heat transfer coefficient and heat transfer area respectively; is the heat transfer of the hot and cold streams; LMTD k is the logarithmic mean temperature difference of the i-th heat exchange unit.

6. A multi-stream heat exchanger pinch point design and modeling device based on Modelica language, characterized in that: The device constructs a multi-stream heat exchanger model based on the Modelica language and adopts a modular design to realize the dynamic coupling of the heat exchange system. It at least includes: a stream compounding and initial configuration module, an enthalpy interval segmentation and multi-equilibrium coupling model establishment module, a segmented discrete model establishment module, and a simulation system construction and performance verification module.

7. The multi-stream heat exchanger pinch point design and modeling device based on Modelica language according to claim 6, characterized in that: The stream recombination and initial configuration module is used to set the isothermal section according to the inlet and outlet temperatures of each stream, recombine the hot and cold streams respectively, and define the temperature range by cross-analyzing the composite temperature enthalpy lines of the hot and cold streams to achieve the initial configuration of the heat recovery path; The enthalpy interval segmentation and multi-equilibrium coupling model establishment module is used to segment the enthalpy interval of the multi-stream heat exchanger according to the inflection point, call the CoolProp physical property library to obtain phase change parameters and thermophysical property data, and establish a multi-equilibrium coupling model based on the energy balance equation, mass conservation equation, and momentum conservation equation to describe the interaction behavior of the streams; The segmented discrete model building module is used to discretize the interior of the heat exchange section into n heat exchange units, establish a segmented discrete model, calculate the internal temperature field of the entire multi-stream heat exchanger, and determine the pinch point of the heat exchange process and the heat exchanger efficiency; The simulation system construction and performance verification module is used to construct a pinch point analysis simulation system for the multi-stream heat exchanger based on the segmented discrete model of the multi-stream heat exchanger in combination with actual design conditions, analyze the heat transfer area of the multi-stream heat exchanger, the outlet temperature of the multi-stream heat exchanger, the location of the internal pinch point and the minimum heat transfer temperature difference, and verify the system performance and response characteristics.

8. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language as described in any one of claims 1 to 5.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the multi-stream heat exchanger pinch point design and modeling method based on the Modelica language according to any one of claims 1 to 5 when executed.

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