A data fitting method of a heat exchange pipe of a gas-liquid matching heat exchanger, a simulation method and system of the heat exchanger

Abstract

The present application relates to heat exchanger technical field, disclose a kind of data fitting method of gas-liquid matching heat exchanger's heat exchange tube, the simulation method and system of heat exchanger, comprising the following steps: constructing gas-liquid matching heat exchanger's heat exchange tube partial model, divide several microelement sections;Each microelement section is divided into two-phase section, superheated section;If two-phase section, then calculate the heat exchange amount of working medium in microelement section;Iterative calculation of the outlet dryness of heat exchange tube, and calculate the pressure drop and outlet pressure of this microelement section;If superheated section, then calculate the maximum heat exchange amount of microelement section, thermal resistance, heat exchange amount, outlet temperature of working medium, pressure drop and outlet pressure, carry out the calculation of next microelement section and fit into database, call database data simulation heat exchange tube heat exchange, realize the simulation of gas-liquid matching heat exchanger.The present application solves the problem that the pressure drop between adjacent tube passes is not considered in the prior art, leading to inaccurate simulation, and has the characteristics of numerical simulation of gas-liquid matching heat exchanger.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat exchangers, and more particularly, to a data fitting method for heat exchange tubes of a gas-liquid distribution heat exchanger, a simulation method and system for the heat exchanger. BACKGROUND

[0002] A heat exchanger is a device for realizing heat transfer of fluids at different temperatures, and its heat transfer performance has an important influence on the energy efficiency of a thermal system. Therefore, some scholars have proposed changing the dryness distribution in the heat exchanger by distributing liquid phase to improve the performance of the heat exchanger, and this type of heat exchanger is called a gas-liquid distribution heat exchanger. The header-small hole type gas-liquid distribution unit has become one of the mainstream liquid distribution structures of the gas-liquid distribution heat exchanger due to its simple structure, good separation performance, and the advantage of being integrated into the heat exchanger. The gas-liquid distribution heat exchanger is divided into a liquid distribution condenser and a liquid distribution evaporator. The liquid distribution condenser reduces the liquid film thickness by promptly removing the liquid phase, thereby reducing the heat transfer resistance and enhancing the heat transfer in the condensation process. The heat transfer coefficient increases first and then decreases with the increase of the dryness in the evaporation process. The liquid distribution evaporator improves the dryness distribution of the evaporator as a whole by distributing part of the liquid phase at the low dryness inlet to increase the inlet dryness, and supplementing the part of the liquid phase to the high dryness area to reduce the dryness, thereby improving the efficient heat transfer area.

[0003] Therefore, the liquid distribution hole discharge amount is crucial to the performance of the gas-liquid distribution heat exchanger. However, the discharge amount of the liquid distribution hole is not only affected by the structure of the header-small hole type gas-liquid distribution unit, but also related to the pressure drop between adjacent tube passes. Meanwhile, unreasonable structure design may cause gas leakage of the liquid distribution hole, and even deteriorate the performance of the heat exchanger.

[0004] The prior art has a simulation calculation method for a working condition of a heat exchanger system, the heat exchanger system comprising a heat exchanger group composed of a plurality of heat exchanger units, the simulation calculation method comprising the steps of: establishing a three-dimensional simulation model of the heat exchanger unit; performing three-dimensional simulation calculation on the three-dimensional simulation model to obtain heat exchange characteristic information of the heat exchanger unit; wherein the heat exchange characteristic information comprises flow characteristic information and temperature characteristic information; establishing a one-dimensional simulation model of the heat exchanger group; performing simulation calculation on the one-dimensional simulation model based on the heat exchange characteristic information to obtain flow distribution results of the heat exchanger group; and performing three-dimensional simulation calculation on each heat exchanger unit in the heat exchanger group according to the flow distribution results to obtain simulation calculation results of the heat exchanger system. By this means, the present application can reduce the simulation calculation cost and provide simulation calculation efficiency.

[0005] However, the existing gas-liquid distribution heat exchanger simulation mainly simulates the performance of the gas-liquid distribution heat exchanger by assuming the liquid distribution amount, and the existing model also assumes that the flow distribution of each tube is uniform, without considering the deterioration of the heat exchange performance caused by uneven flow distribution, so how to invent a method that can accurately simulate the flow and heat exchange in the gas-liquid distribution heat exchanger is a technical problem that needs to be solved in the technical field. SUMMARY

[0006] The present application provides a data fitting method for heat exchange tubes of a gas-liquid distribution heat exchanger, a simulation method and system for heat exchangers, which can realize numerical simulation of the gas-liquid distribution heat exchanger.

[0007] To achieve the above-mentioned purposes of the present application, the technical solutions adopted are as follows:

[0008] A data fitting method for heat exchange tubes of a gas-liquid distribution heat exchanger, comprising the following specific steps:

[0009] Constructing a heat exchange tube part model of the gas-liquid distribution heat exchanger, dividing the heat exchange tube part model into a plurality of micro-segments; based on the set inlet quality, dividing each micro-segment into a two-phase segment and a superheated segment;

[0010] For each micro-segment:

[0011] If it is a two-phase segment, calculate the heat exchange amount of the working medium in the micro-segment; iteratively calculate the outlet quality of the heat exchange tube according to the heat exchange amount, and further calculate the pressure drop and outlet pressure of the micro-segment; the outlet pressure, flow rate and quality are taken as the inlet conditions of the next micro-segment for the calculation of the next micro-segment;

[0012] If it is a superheated segment, calculate the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop and outlet pressure of the micro-segment, and take the outlet pressure, flow rate and temperature as the inlet conditions of the next micro-segment for the calculation of the next micro-segment;

[0013] The heat exchange amount, pressure drop and outlet quality of the heat exchange tube under different inlet flow rates and qualities are fitted into a database.

[0014] Preferably, the heat exchange tube part model of the gas-liquid distribution heat exchanger is constructed, and the specific steps are as follows:

[0015] Obtain the heat exchange tube structure parameters including tube length, tube number, tube spacing, outer diameter, inner diameter and thermal conductivity;

[0016] If it is an internally threaded tube, the number of grooves, groove bottom width, tooth height, tooth top angle and spiral angle are also obtained;

[0017] If there are mounting fins outside, input fin parameters are also obtained;

[0018] The ε-NTU method is used to simulate the heat exchange pipe section, and a one-dimensional heat exchange pipe section model is constructed.

[0019] Further, based on the set inlet dryness, each micro-element section is divided into two-phase section and superheated section, specifically: the micro-element section with inlet dryness less than 1 is divided into two-phase section, and the micro-element section with inlet dryness equal to 1 is divided into superheated section.

[0020] Further, if it is a two-phase section, the heat exchange amount of the working medium in the micro-element section is calculated; the outlet dryness of the heat exchange pipe is iteratively calculated according to the heat exchange amount, and the pressure drop and outlet pressure of the micro-element section are further calculated, and the specific steps are:

[0021] The outlet dryness of the micro-element section is assumed to be:

[0022] x i,out,a =x i,in +0.01

[0023] Wherein: x i,out,a is the assumed outlet dryness of the i-th micro-element section, x i,in is the inlet dryness of the i-th micro-element section;

[0024] The average dryness of the working medium is determined by taking the average dryness of the inlet and outlet, and the average dryness x i of the i-th micro-element section is calculated.

[0025]

[0026] The heat flux q is calculated by the inlet dryness and the outlet dryness:

[0027]

[0028] Wherein, G is the refrigerant flow, ΔH is the latent heat of the refrigerant, D is the outer diameter of the heat exchange pipe, L i is the micro-element section length of the heat exchange pipe, and mesh is the number of micro-element sections;

[0029] The refrigerant side heat transfer coefficient h r and the pipe outside heat transfer coefficient h a are calculated by the heat transfer correlation, and the total thermal resistance UA is calculated:

[0030]

[0031] Wherein, d is the inner diameter of the heat exchange pipe, and λ is the heat conduction coefficient of the heat exchange pipe wall;

[0032] The heat transfer unit number NTU is calculated:

[0033]

[0034] wherein C min is the specific heat capacity of the small specific heat capacity fluid in the fluid inside and outside the tube;

[0035] Calculate the heat transfer effectiveness ε:

[0036] ε = 1 - e -NTU

[0037] Calculate the theoretical maximum heat exchange amount Q max :

[0038] Q max = C min (T a,dry,in -T i,in )

[0039] wherein T a,dry,in is the air side dry bulb temperature, and T i,in is the inlet temperature of the micro-element section refrigerant;

[0040] According to ε, calculate the heat exchange amount Q i under the assumed outlet dryness and the corresponding outlet dryness:

[0041] Q i = ε·Q max

[0042]

[0043] wherein Q i is the micro-element section heat exchange amount, and x i,out,c is the calculated outlet dryness;

[0044] Determine whether the assumed outlet dryness and the calculated outlet dryness converge:

[0045]

[0046] If not converged, take the calculated outlet dryness x i,out,c as the new assumed outlet dryness x i,out,a , return to the step of calculating the i-th micro-element section average dryness, and repeat the iteration until convergence;

[0047] If converged, calculate the micro-element section pressure drop ΔP i and the micro-element section outlet pressure P i,out according to the two-phase flow pressure drop correlation, and take the outlet conditions as the inlet conditions of the next micro-element section.

[0048] Furthermore, if it is a superheated section, calculate the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop, and outlet pressure of the micro-element section, and the specific steps are as follows:

[0049] Calculate the maximum heat exchange amount of the micro-element section:

[0050] Q max = C min (T a,dry,in -T i,in )

[0051] C min = min(C r ,C a )

[0052] wherein C r is the specific heat capacity of the refrigerant, C a is the specific heat capacity of the air;

[0053] The heat transfer coefficient on the refrigerant side h r in the superheating section is calculated according to the heat transfer correlation, and then the total thermal resistance UA and the number of heat transfer units NTU are calculated:

[0054]

[0055] The heat transfer effectiveness ε is calculated according to the ε-NTU correlation for non-phase-change maldistribution:

[0056]

[0057] C max = max(C r ,C a )

[0058]

[0059] The heat exchange Q i under the assumed outlet dryness and the outlet temperature are calculated according to ε:

[0060] Q i = ε·Q max

[0061]

[0062] The pressure drop ΔP i of the micro-element section and the outlet pressure P i,out of the micro-element section are calculated according to the superheating section pressure drop correlation, and the outlet conditions are taken as the inlet conditions of the next micro-element section.

[0063] Furthermore, the heat exchange, pressure drop and outlet dryness of the heat exchange tube under different inlet flow rates and dryness are fitted into a database, and the specific steps are as follows: the flow rate range is divided into several flow rates according to the set step size, the heat exchange, pressure drop and outlet dryness of each flow rate at several inlet dryness are calculated, the relationship between the pressure drop and the flow rate at each inlet dryness, and the relationship between the outlet dryness and the flow rate are fitted, and the fitted correlation is taken as the database.

[0064] A simulation method of a gas-liquid distribution heat exchanger, based on the data fitting method of the heat exchange tube, comprising the following specific steps:

[0065] Constructing a header part model of the gas-liquid distribution heat exchanger;

[0066] The simulation of the gas-liquid distribution heat exchanger is realized by simulating the flow in the header through three-dimensional fluid mechanics calculation: the outlet flow rate and dryness of the inlet header are monitored each time, the outlet dryness after heat exchange by the heat exchange tube and the pressure drop of the heat exchange tube are called from the database according to the outlet flow rate and dryness of the inlet header, the outlet flow rate and outlet dryness are taken as the inlet conditions of the outlet header, and the inlet pressure of the outlet header is monitored, and the pressure is added to the pressure drop of the heat exchange tube as the outlet pressure of the inlet header.

[0067] Preferably, when constructing the header part model of the gas-liquid distribution heat exchanger, a three-dimensional physical model including several headers is constructed; for the three-dimensional physical model of each header, structured grid division is performed, and if the header part has a perforated plate, the grid at the liquid distribution hole of the perforated plate is encrypted.

[0068] Further, the simulation of the gas-liquid distribution heat exchanger is realized by simulating the flow in the header through three-dimensional fluid mechanics calculation: the inlet header and the outlet header are put into the same case for simulation by using ANSYS fluent software, and the flow and heat exchange of the heat exchange tube are replaced by a user-defined equation UDF; in ANSYS fluent, the inlet header uses a velocity inlet boundary condition, and the outlet header uses a pressure outlet boundary condition; when the UDF is used to replace the heat exchange tube, the outlet parameters of the inlet header are monitored, the heat transfer and pressure drop are calculated based on the database, the outlet parameters of the heat exchange tube are obtained as the inlet conditions of the outlet header, the inlet pressure of the outlet header is monitored, and the pressure drop of the heat exchange tube is added based on the database as the outlet pressure boundary condition of the inlet header.

[0069] A gas-liquid distribution heat exchanger simulation system for executing the simulation method of the gas-liquid distribution heat exchanger, comprising a modeling module, a heat exchange tube simulation module, a database fitting module, and a gas-liquid distribution heat exchanger simulation module:

[0070] The modeling module is used to construct a heat exchange tube part model and a header part model of the gas-liquid distribution heat exchanger;

[0071] The heat exchange pipe simulation module is used for dividing the heat exchange pipe part model into a plurality of micro-segments; based on the set inlet dryness, each micro-segment is divided into a two-phase segment and a superheated segment; for each micro-segment: if it is a two-phase segment, the heat exchange amount of the working medium in the micro-segment is calculated; the outlet dryness of the heat exchange pipe is iteratively calculated according to the heat exchange amount, and the pressure drop and the outlet pressure of the micro-segment are further calculated; the outlet pressure, flow and dryness are taken as the inlet conditions of the next micro-segment to calculate the next micro-segment; if it is a superheated segment, the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop and outlet pressure of the micro-segment are calculated, and the outlet pressure, flow and temperature are taken as the inlet conditions of the next micro-segment to calculate the next micro-segment;

[0072] The database fitting module is used for fitting the heat exchange amount, pressure drop and outlet dryness of the heat exchange pipe under different inlet flow and dryness into a database;

[0073] The gas-liquid matching heat exchanger simulation module is used for simulating the flow in the header tank by adopting three-dimensional fluid mechanics calculation, so as to realize the simulation of the gas-liquid matching heat exchanger: the outlet flow and dryness of the inlet header tank are monitored each time, the outlet dryness and the pressure drop of the heat exchange pipe after heat exchange are called in the database according to the outlet flow and dryness of the inlet header tank, the outlet flow and outlet dryness are taken as the inlet conditions of the outlet header tank, and the inlet pressure of the outlet header tank is monitored, and the pressure drop of the heat exchange pipe is added to the inlet pressure as the outlet pressure of the inlet header tank.

[0074] The beneficial effects of the present application are as follows:

[0075] The simulation method of the gas-liquid matching heat exchanger is disclosed, the gas-liquid matching heat exchanger is divided into a header tank and a heat exchange pipe two parts, the heat exchange pipe part model is divided into a plurality of micro-segments for simulation in the heat exchange pipe part, the heat exchange amount, pressure drop and outlet dryness of the heat exchange pipe under different inlet flow and dryness are fitted into a database, the header tank part model is constructed, and the gas-liquid matching heat exchanger simulation is carried out based on the database and the header tank part model; therefore, the present application realizes accurate simulation of flow distribution in the header tank-small hole type gas-liquid matching unit under less calculation amount, considers the coupling relationship between the heat exchange pipe pressure drop and the header tank flow distribution, can realize numerical simulation of the gas-liquid matching heat exchanger, accurately and efficiently calculates the working medium distribution, heat transfer performance and pressure drop of the heat exchanger under different working conditions and structures, provides technical support for optimization of the gas-liquid matching heat exchanger, and reduces the research and development cost. BRIEF DESCRIPTION OF DRAWINGS

[0076] Figure 1 It is a flow schematic diagram of the data fitting method of the heat exchange pipe of the gas-liquid matching heat exchanger of the present application.

[0077] Figure 2 It is a structure schematic diagram of the gas-liquid matching heat exchanger in embodiment 1.

[0078] Figure 3 A simulation diagram of the heat exchange tube in Example 1.

[0079] Figure 4 A simulation flow chart of the heat exchange tube in Example 1.

[0080] Figure 5 A simulation method flow chart of the gas-liquid distribution heat exchanger in Example 2.

[0081] Figure 6 A simulation diagram of the gas-liquid distribution heat exchanger in Example 2.

[0082] Figure 7 A specific simulation flow chart of the gas-liquid distribution heat exchanger in Example 2.

[0083] Figure 8 A structure simulation diagram of the gas-liquid distribution evaporator in Example 3.

[0084] Figure 9 A phase distribution diagram of the upper half of the gas-liquid distribution evaporator in Example 3.

[0085] Figure 10 A phase distribution diagram of the lower half of the gas-liquid distribution evaporator in Example 3.

[0086] Figure 11 A flow distribution diagram of the gas-liquid distribution evaporator tube in Example 3.

[0087] Figure 12 A heat exchange amount diagram of the gas-liquid distribution evaporator tube in Example 3.

[0088] In the figure, 1 is a fin, 2 is a heat exchange tube, 3 is a heat exchange tube inlet, 4 is a liquid distribution hole plate, 5 is a heat exchange tube outlet, and 6 is a blind plate. DETAILED DESCRIPTION

[0089] The present application will be described in detail below in conjunction with the drawings and specific embodiments.

[0090] Example 1

[0091] As shown in the figure, a data fitting method of a heat exchange tube of a gas-liquid distribution heat exchanger includes the following specific steps: Figure 1

[0092] A heat exchange tube part model of the gas-liquid distribution heat exchanger is constructed, and the heat exchange tube part model is divided into a plurality of micro-element segments; based on a set inlet dryness, each micro-element segment is divided into a two-phase segment and a superheated segment.

[0093] For each micro-element segment:

[0094] ​If it is two-phase section, the heat exchange amount of the working medium in the micro-element section is calculated; the outlet dryness of the heat exchange tube is iteratively calculated according to the heat exchange amount, and the pressure drop and outlet pressure of the micro-element section are further calculated; the outlet pressure, flow and dryness are taken as the inlet conditions of the next micro-element section to calculate the next micro-element section;

[0095] If it is superheated section, the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop and outlet pressure of the micro-element section are calculated, and the outlet pressure, flow and temperature are taken as the inlet conditions of the next micro-element section to calculate the next micro-element section;

[0096] The heat exchange amount, pressure drop and outlet dryness of the heat exchange tube under different inlet flow and dryness are fitted into a database.

[0097] In the embodiment, the gas-liquid distribution heat exchanger structure is as shown in Figure 2 The gas-liquid distribution heat exchanger is divided into a liquid distribution condenser and a liquid distribution evaporator, the liquid distribution condenser reduces the liquid film thickness by timely removing the liquid phase, reduces the heat transfer thermal resistance, and thus enhances the heat transfer in the condensation process. The heat transfer coefficient in the evaporation process increases first and then decreases with the increase of the dryness. The liquid distribution evaporator improves the dryness distribution of the evaporator as a whole by removing part of the liquid phase at the low dryness inlet to increase the inlet dryness, and supplementing the part of the liquid phase to the high dryness area to reduce the dryness. Therefore, the working medium flow area in the gas-liquid distribution evaporator can be divided into two parts, one part is the header-small hole type gas-liquid distribution unit for gas-liquid distribution of the working medium, and the other part is the heat exchange tube section for heat exchange with the heat source. The simulation of the gas-liquid distribution evaporator can be divided into the simulation of the two parts. Since the two-phase flow in the header is very complex, the three-dimensional CFD is used to simulate the header. For the heat exchange tube section, the heat exchange amount, pressure drop and outlet parameters of the working medium are mainly concerned, and the specific flow state in the heat exchange tube does not need to be known. Meanwhile, the heat exchange process of the heat exchange tube has been studied by many scholars, and high-precision empirical formula is obtained, which can be used to calculate the heat exchange and pressure drop of the working medium in the heat exchange tube. Therefore, considering the simulation accuracy and calculation amount, a one-dimensional heat exchange tube model is established, and the ε-NTU method is used to simulate the heat exchange tube section to calculate the heat transfer coefficient, heat exchange amount, pressure drop and outlet parameters.

[0098] In this embodiment, the outer tube heat exchange fluid is air, and the air exchanges heat with the refrigerant in the steady state condition, and the heat exchange tube is the core of heat exchange, and the gas-liquid distribution in the header affects the heat exchange capacity and pressure drop of the heat exchange tube, and the pressure drop of the heat exchange tube in turn affects the liquid distribution of the distribution hole in the header, and further affects the two-phase distribution of each heat exchange tube, therefore, the gas-liquid distribution heat exchanger is divided into two parts of the header and the heat exchange tube, firstly, a one-dimensional model of the heat exchange tube is established, the relationship between the outlet dryness of the heat exchange tube, the pressure drop and the inlet flow, the dryness is fitted into a correlation, then a three-dimensional model of the left header and the right header is established, Fluent is used for simulation calculation, the inlet and outlet parameters of the header are monitored by UDF, the correlation obtained by the heat exchange tube model is processed, and the corresponding parameters are obtained as new boundary conditions, so that the modeling of the heat exchange tube part is replaced by UDF in Fluent, and a gas-liquid distribution heat exchanger model with small calculation amount and high precision is established.

[0099] In one specific embodiment, the heat exchange tube part model of the gas-liquid distribution heat exchanger is constructed, and the specific steps are as follows:

[0100] The heat exchange tube structure parameters including tube length, tube number, tube spacing, outer diameter, inner diameter and thermal conductivity are obtained;

[0101] If it is an internal threaded tube, the number of grooves, groove bottom width, tooth height, tooth top angle and spiral angle are also obtained;

[0102] If there are mounting fins outside, input fin parameters such as fin thickness, fin width, fin height, fin number, fin spacing and fin thermal conductivity are also obtained;

[0103] The ε-NTU method is used for simulation of the heat exchange tube section, and a one-dimensional heat exchange tube part model is constructed. The one-dimensional heat exchange tube part model is mainly suitable for cross-flow or large heat capacity of the outer tube heat exchange fluid, and the corresponding physical property parameters of the outer tube heat exchange fluid are also required.

[0104] In this embodiment, the heat exchange tube part model is divided into a plurality of micro-element sections as shown in Figure 3 Each micro-element section includes an air side inlet, an air side outlet, a working medium side inlet and a working medium side outlet; the inlet dryness is given by simultaneously giving the air side inlet and the working medium side inlet dryness.

[0105] In one specific embodiment, based on the set inlet dryness, each micro-element section is divided into a two-phase section and a superheated section, specifically: the micro-element section with an inlet dryness less than 1 is divided into a two-phase section, and the micro-element section with an inlet dryness equal to 1 is divided into a superheated section.

[0106] In one specific embodiment, as shown in Figure 4As shown, if it is two-phase section, the heat exchange amount of the working medium in the micro-element section is calculated; the outlet dryness of the heat exchange pipe is iteratively calculated according to the heat exchange amount, and the pressure drop and outlet pressure of the micro-element section are further calculated, and the specific steps are as follows:

[0107] The outlet dryness of the micro-element section is assumed to be:

[0108] x i,out,a =x i,in +0.01

[0109] Wherein, x i,out,a is the assumed outlet dryness of the i-th micro-element section, and x i,in is the inlet dryness of the i-th micro-element section.

[0110] The average dryness x i of the i-th micro-element section is calculated by taking the average dryness of the inlet and outlet.

[0111]

[0112] The heat flux q is calculated by the inlet dryness and the outlet dryness:

[0113]

[0114] Wherein, G is the refrigerant flow, ΔH is the latent heat of the refrigerant called by refprop according to the inlet pressure of the refrigerant, D is the outer diameter of the heat exchange pipe, L i is the micro-element section length of the heat exchange pipe, and mesh is the number of micro-element sections.

[0115] The refrigerant-side heat transfer coefficient h r and the pipe-outer-side heat transfer coefficient h a are calculated by the heat transfer correlation, and the total thermal resistance UA is calculated:

[0116]

[0117] Wherein, d is the inner diameter of the heat exchange pipe, and λ is the heat conduction coefficient of the wall surface of the heat exchange pipe.

[0118] The heat transfer unit number NTU is calculated:

[0119]

[0120] Wherein, C min is the specific heat capacity of the small specific heat capacity fluid in the pipe-in and pipe-out fluid, which is air here.

[0121] The heat transfer effectiveness is calculated:

[0122] ε=1-e -NTU

[0123] The theoretical maximum heat exchange amount Q is calculatedmax :

[0124] Q max =C min (T a,dry,in -T i,in )

[0125] where T a,dry,in is the air-side dry-bulb temperature, T i,in is the micro-element segment refrigerant inlet temperature called by refprop according to the inlet pressure of the refrigerant;

[0126] According to ε, the heat transfer amount Q i under the assumed outlet dryness is calculated, and the corresponding outlet dryness is calculated:

[0127] Q i = ε·Q max

[0128]

[0129] where Q i is the micro-element segment heat transfer amount, and x i,out,c is the calculated outlet dryness;

[0130] It is judged whether the assumed outlet dryness and the calculated outlet dryness converge:

[0131]

[0132] If not, the calculated outlet dryness x i,out,c is taken as the new assumed outlet dryness x i,out,a , and the step of calculating the i-th micro-element segment average dryness is returned to, and iteration is repeated until convergence;

[0133] If convergence is achieved, the micro-element segment pressure drop ΔP i and the micro-element segment outlet pressure P i,out are calculated according to the two-phase flow pressure drop correlation, and the outlet conditions are taken as the inlet conditions of the next micro-element segment.

[0134] In one specific embodiment, if it is a superheated segment, the maximum heat transfer amount, thermal resistance, heat transfer amount, outlet temperature of the working medium, pressure drop, and outlet pressure of the micro-element segment are calculated, and the specific steps are as follows:

[0135] The maximum heat transfer amount of the micro-element segment is calculated:

[0136] Q max = C min (T a,dry,in -T i,in )

[0137] C min = min(Cr ,C a )

[0138] wherein, C r is the specific heat capacity of refrigerant, C a is the specific heat capacity of air;

[0139] According to the heat transfer correlation, the heat transfer coefficient on the refrigerant side h r in the superheating section is calculated, and then the total thermal resistance UA and the number of heat transfer units NTU are calculated:

[0140]

[0141] According to the ε-NTU correlation of the non-phase-change maldistribution, the heat transfer effectiveness ε is calculated:

[0142]

[0143] C max = max(C r , C a )

[0144]

[0145] According to ε, the heat exchange Q i under the assumed outlet dryness and the outlet temperature are calculated:

[0146] Q i = ε·Q max

[0147]

[0148] According to the superheating section pressure drop correlation, the micro-element section pressure drop ΔP i and the micro-element section outlet pressure P i,out are calculated, and the outlet conditions are taken as the inlet conditions of the next micro-element section.

[0149] In one specific embodiment, the heat exchange of the heat exchange tube under different inlet flow rates and dryness, the pressure drop and the outlet dryness are fitted into a database, and the specific steps are as follows: the flow rate range is divided into the range of 0.5 g / s-20 g / s according to the set step, a plurality of flow rates with a step of 0.1 g are calculated, the heat exchange, the pressure drop and the outlet dryness of each flow rate at 0, 0.1, 0.2, 0.3 ··· 0.9, 1 are calculated, the relationship between the pressure drop and the flow rate at each inlet dryness, the relationship between the outlet dryness and the flow rate are fitted, and the fitted correlation is taken as the database.

[0150] Example 2

[0151] As Figure 5As shown in the simulation method of a gas-liquid matching heat exchanger, based on the data fitting method of the heat exchange tube, the simulation method comprises the following specific steps:

[0152] Constructing a header part model of the gas-liquid matching heat exchanger;

[0153] The simulation of the gas-liquid matching heat exchanger is realized by simulating the flow in the header through three-dimensional fluid mechanics calculation: the outlet flow rate and dryness of the inlet header are monitored each time, the outlet dryness after heat exchange through the heat exchange tube and the pressure drop of the heat exchange tube are called from the database according to the outlet flow rate and dryness of the inlet header, the outlet flow rate and outlet dryness are taken as the inlet conditions of the outlet header, and the inlet pressure of the outlet header is monitored, and the pressure drop of the heat exchange tube is added to the inlet pressure of the inlet header as the outlet pressure of the inlet header.

[0154] More specifically, in one specific embodiment, when the header part model is constructed, a three-dimensional physical model comprising several headers is constructed; for the three-dimensional physical model of each header, structured grid division is performed, and if the header part has a perforated plate, the grid at the liquid distribution hole of the perforated plate is encrypted.

[0155] In one specific embodiment, as shown in the simulation method of a gas-liquid matching heat exchanger, based on the data fitting method of the heat exchange tube, the simulation method comprises the following specific steps: Figure 6

[0156] As shown in the simulation method of a gas-liquid matching heat exchanger, based on the data fitting method of the heat exchange tube, the simulation method comprises the following specific steps: Figure 7 ​As shown, when the header is simulated by Fluent, the left and right headers are simulated as an inlet header and an outlet header in the same case respectively due to the mutual influence of the flow in the left and right headers, and the flow and heat exchange of the heat exchange tube are replaced by UDF, so as to realize the simulation of the gas-liquid matching heat exchanger. In Fluent, the header inlet adopts a velocity inlet boundary condition, and the header outlet adopts a pressure outlet boundary condition. The UDF is used to replace the heat exchange tube, and the following functions need to be realized: monitoring the outlet parameters of the inlet header (the inlet parameters of the heat exchange tube), calculating the heat transfer and pressure drop, obtaining the outlet parameters of the heat exchange tube as the inlet conditions (flow rate and dryness) of the outlet header, since the pressure drop of the heat exchange tube will affect the header distribution in the header, it needs to be considered, the inlet pressure of the outlet header (the outlet pressure of the heat exchange tube) is monitored by UDF and the pressure drop of the heat exchange tube is added as the outlet pressure boundary condition (the inlet pressure of the heat exchange tube) of the inlet header. Thus, the calculation is realized by using UDF to replace the heat exchange tube, which greatly reduces the calculation amount.

[0157] Example 3

[0158] In this embodiment, as shown in Figure 8 , the simulation method of the gas-liquid matching heat exchanger is used to simulate a gas-liquid matching evaporator with three tube passes and a tube number distribution of 2-2-2; wherein the evaporator is provided with a plurality of fins, liquid distribution is performed at the first tube pass liquid distribution hole plate 3, liquid is supplemented at the third tube pass inlet, the blind plate 6 is used for flow control, and the heat exchange tube 2 is a tube with internal threads and external fins 1. The refrigerant enters from the upper heat exchange tube inlet 3 of the evaporator, exchanges heat through the three tube passes, and then flows out from the lower heat exchange tube outlet 5 of the evaporator.

[0159] The gas-liquid matching evaporator is divided into a header and a heat exchange tube;

[0160] In this embodiment, the heat exchange tube part model of the gas-liquid matching heat exchanger is constructed, specifically:

[0161] The inlet flow rate is 7.4 g, the inlet dryness is 0.1, the refrigerant is R134a, the header structure parameters of the physical model are shown in Table 1, the heat exchange tube structure parameters are shown in Table 2, and the fin structure parameters are shown in Table 3.

[0162] Table 1 Header structure parameters

[0163]

[0164]

[0165] Table 2 Heat exchange tube parameters

[0166]

[0167] Table 3 Fin parameters

[0168]

[0169] Based on the above parameters, the heat exchange tube part model of the gas-liquid matching heat exchanger is constructed:

[0170] Tube thickness:

[0171]

[0172] Root circle cross-sectional area:

[0173]

[0174] Addendum circle cross-sectional area:

[0175]

[0176] Addendum circle cross-sectional area:

[0177]

[0178] Equivalent diameter (calculated by 4 times the area at the circumference according to the definition):

[0179]

[0180] Total heat exchange area on the air side:

[0181]

[0182] Heat exchange area on the air side of each micro-element section:

[0183]

[0184] Heat exchange tube radius:

[0185]

[0186] Equivalent ring rib radius:

[0187]

[0188] Equivalent rib height:

[0189]

[0190] Root heat exchange area:

[0191]

[0192] Rib surface heat exchange area:

[0193]

[0194] Rib surface total efficiency:

[0195]

[0196] η: rib efficiency

[0197] The air side air inlet temperature is divided into dry bulb temperature and wet bulb temperature, and the dry bulb temperature is:

[0198]

[0199] The air side inlet wet bulb temperature is:

[0200]

[0201] The heat exchange tube part model of the gas-liquid matching heat exchanger is constructed, and the heat exchange tube part model is divided into a plurality of micro-element sections; based on the set inlet dryness, each micro-element section is divided into a two-phase section and a superheated section:

[0202] In this embodiment, the refrigerant in the heat exchange tube is divided into two-phase flow and superheated vapor flow. Since the two-phase flow is in the heat exchange tube, the phase change dryness increases, and the physical property changes greatly with the dryness. The temperature slightly decreases with the decrease of the pressure, while the superheated flow absorbs heat to continuously increase the temperature in the heat exchange tube. The two-phase flow is measured by dryness to measure its state, and the superheated vapor flow is measured by temperature. The two-phase flow and the superheated vapor flow have different flow patterns, and the heat exchange coefficient and the pressure drop have great differences. Therefore, different empirical formulas should be used for the two flow states. For the heat exchange tube model, the main concern is the refrigerant heat exchange amount and the pressure drop, so the empirical formula is used to calculate the heat transfer coefficient and the pressure drop. The selected heat transfer correlation and pressure drop correlation are shown in Table 4.

[0203] Table 4 Heat transfer correlation and pressure drop correlation

[0204]

[0205]

[0206]

[0207] For each micro-element section:

[0208] If it is a two-phase section, the heat exchange amount of the working medium in the micro-element section is calculated; the outlet dryness of the heat exchange tube is iteratively calculated according to the heat exchange amount, and the pressure drop and the outlet pressure of the micro-element section are further calculated; the outlet pressure, flow and dryness are taken as the inlet conditions of the next micro-element section for the calculation of the next micro-element section;

[0209] If it is a superheated section, the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop and outlet pressure of the micro-element section are calculated, and the outlet pressure, flow and temperature are taken as the inlet conditions of the next micro-element section for the calculation of the next micro-element section;

[0210] The heat exchange amount, pressure drop and outlet dryness of the heat exchange pipe under different inlet flow and dryness are fitted into a database;

[0211] A three-dimensional physical model including several headers is constructed; for the three-dimensional physical model of each header, structured grid division is performed, and if the header part has a perforated plate, the grid at the distribution hole of the perforated plate is encrypted.

[0212] The flow in each three-dimensional physical model of the header is simulated:

[0213] During the simulation of each header, the outlet flow and dryness of the inlet header are monitored, the outlet dryness after heat exchange by the heat exchange pipe and the pressure drop of the heat exchange pipe are called from the database according to the outlet flow and dryness of the inlet header, the outlet flow and outlet dryness are taken as the inlet conditions of the outlet header, and the inlet pressure of the outlet header is monitored, and the pressure is added to the pressure drop of the heat exchange pipe as the outlet pressure of the inlet header.

[0214] The flow in each three-dimensional physical model of the header is simulated by using three-dimensional fluid mechanics calculation, the simulation of the gas-liquid distribution heat exchanger is realized, specifically, ANSYS fluent software is used to simulate the flow in each three-dimensional physical model of the header, left and right two headers are put into the same case for simulation each time, and a user-defined equation UDF is used to replace the flow heat exchange of the heat exchange pipe; in ANSYS fluent, the header inlet adopts a velocity inlet boundary condition, and the header outlet adopts a pressure outlet boundary condition; when the UDF is used to replace the heat exchange pipe, the outlet parameters of the inlet header are monitored, the heat transfer and pressure drop are calculated based on the database, the outlet parameters of the heat exchange pipe are obtained as the inlet conditions of the outlet header, the inlet pressure of the outlet header is monitored, and the pressure drop of the heat exchange pipe is added based on the database as the outlet pressure boundary condition of the inlet header.

[0215] In this embodiment, when the header is simulated by using ANSYS Fluent, the Eulerian model is selected for the multiphase flow model, the realizable"k-ε" model is selected for the turbulent flow model, the non-equilibrium wall surface function is selected for wall surface processing, the Pressure-Based is selected for the solver, the steady-state solution is selected, the finite volume method (FVM) is selected for the discrete method, the SIMPLE algorithm is selected for the velocity-pressure coupling, the PRESTO format is selected for the pressure discretization, and the second-order upwind discrete format is selected for other fluxes.

[0216] In this embodiment, since the loaded UDF monitors data and assigns values at each step, repeated iterations are performed. If the entire evaporator is simulated, a total of 12 surfaces are loaded with UDFs for iteration. In order to improve the convergence speed of the header model, the model is further simplified. It is assumed that the pressure at the outlet of the distribution hole and the outlet of the second tube is the same. The header model is divided into upper and lower parts at the outlet of the second tube. The upper part is the first tube, the inlet of the second tube, and the corresponding header part. The outlet pressure at the distribution hole is taken as a constant. The inlet pressure of the second tube is the outlet pressure of the distribution hole plus the pressure drop of the second tube. The pressure drop of the second tube is obtained by the flow rate and the quality at the inlet of the second tube through the correlation in the UDF. Therefore, the boundary conditions of the upper part model are determined. After the upper part model converges, the pressure difference between the evaporator inlet and the outlet of the distribution hole is the pressure difference of the upper half. The flow rate and the quality of the distribution hole and the second tube obtained are used as the inlet conditions of the lower part model. After the lower part model converges, the pressure difference between the distribution hole and the outlet of the evaporator is the pressure difference of the lower half. The total pressure drop of the evaporator is the pressure difference of the two parts.

[0217] In this embodiment, the simulation results of the upper part of the evaporator are shown in Figure 9 The simulation results of the lower part of the evaporator are shown in Figure 10 The flow distribution of each tube is shown in Figure 11 Due to the difference in density between the gas and liquid phases, the two-phase flow is unevenly distributed in the same tube. The liquid phase is difficult to reach the heat exchange tubes above the same tube, resulting in high inlet quality of the heat exchange tubes above each tube. The outlet is superheated steam, and the heat exchange performance is poor. The heat exchange capacity of each tube is shown in Figure 12 The inlet quality of tubes 3 and 5 is too high, and the heat exchange capacity is much smaller than that of other heat exchange tubes, resulting in a decrease in the performance of the evaporator. The distribution of the distribution hole is 1.69g, which can effectively improve the quality of the first and second tubes. However, due to the distribution, the flow rate also decreases accordingly. The overall impact on the heat exchange capacity is not large. Therefore, when adjusting the gas and liquid, the number of tube distribution should be optimized according to the change in flow rate.

[0218] In this embodiment, in order to measure the uneven distribution of the tube, the difference between the heat exchange capacity of the uniform distribution of the tube flow and the heat exchange capacity obtained by the coupling model is compared under the same distribution amount. It is assumed that the heat exchange capacity of the first tube, the second tube and the third tube of the evaporator is 126.4W, 128.3W and 130.6W respectively when the tube flow is uniformly distributed. Since it does not consider the uneven distribution of gas and liquid, the simulation of the second and third tubes obtained by the coupling model is much larger than the heat exchange capacity obtained by the coupling model. The heat exchange capacity obtained by the coupling model is only 69.1% of the heat exchange capacity obtained by the coupling model. Therefore, when modeling and simulating the heat exchanger, it is very important to consider the uneven distribution of gas and liquid.

[0219] In summary, the method described in the embodiment can quickly and accurately calculate the two-phase distribution, pressure drop and heat exchange capacity of the gas-liquid distribution heat exchanger under different working environments and inlet conditions. According to the different functions of the heat exchange tube and the header and the existing research, a suitable simplified model is established. First, the heat exchange performance of the heat exchange tube under a certain working condition range is calculated, which is fitted into a correlation formula. Then, the flow situation in the header is simulated by Fluent, and the heat transfer and pressure drop of the heat exchange tube are simulated by UDF. First, an inlet pressure of the heat exchange tube is assumed, and the two-phase distribution in the header is obtained. Then, the corresponding pressure drop and outlet dryness of the heat exchange tube under the flow rate are obtained by UDF. The flow rate and outlet dryness are taken as the inlet conditions of the outlet header, and the inlet pressure of the outlet header is added to the pressure drop of the heat exchange tube to obtain the new outlet pressure of the header. The iteration is repeated until the flow rate and pressure of each pipe are stable. This method can accurately and efficiently simulate the two-phase distribution in the header, and simulate the coupling relationship between the pipe pressure drop and the liquid distribution hole distribution. It has the characteristics of wide application range, high calculation efficiency and good accuracy.

[0220] Embodiment 4

[0221] A gas-liquid distribution heat exchanger simulation system for executing the simulation method of the gas-liquid distribution heat exchanger, comprising a modeling module, a heat exchange tube simulation module, a database fitting module, and a gas-liquid distribution heat exchanger simulation module.

[0222] The modeling module is used to build a heat exchange tube part model and a header part model of the gas-liquid distribution heat exchanger.

[0223] The heat exchange tube simulation module is used to divide the heat exchange tube part model into a plurality of micro-segments; based on the set inlet dryness, each micro-segment is divided into a two-phase segment and a superheated segment; for each micro-segment: if it is a two-phase segment, the heat exchange capacity of the working medium in the micro-segment is calculated; the outlet dryness of the heat exchange tube is iteratively calculated according to the heat exchange capacity, and the pressure drop and outlet pressure of the micro-segment are further calculated; the outlet pressure, flow rate and dryness are taken as the inlet conditions of the next micro-segment for the calculation of the next micro-segment; if it is a superheated segment, the maximum heat exchange capacity, thermal resistance, heat exchange capacity, outlet temperature of the working medium, pressure drop and outlet pressure of the micro-segment are calculated, and the outlet pressure, flow rate and temperature are taken as the inlet conditions of the next micro-segment for the calculation of the next micro-segment.

[0224] The database fitting module is used to fit the heat exchange capacity, pressure drop and outlet dryness of the heat exchange tube under different inlet flow rates and dryness into a database.

[0225] The simulation module of the gas-liquid matching heat exchanger is used for simulating the flow in the header tank by adopting three-dimensional fluid mechanics calculation, and realizing the simulation of the gas-liquid matching heat exchanger; the outlet flow and dryness of the inlet header tank are monitored each time, the outlet dryness after heat exchange of the heat exchange pipe and the pressure drop of the heat exchange pipe are called from the database according to the outlet flow and dryness of the inlet header tank, the outlet flow and outlet dryness are taken as the inlet conditions of the outlet header tank, the inlet pressure of the outlet header tank is monitored, and the pressure drop of the heat exchange pipe is added to the inlet pressure of the outlet header tank as the outlet pressure of the inlet header tank.

[0226] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation manners of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A data fitting method for heat exchange tubes of a gas-liquid matching heat exchanger, characterized in that: The method comprises the following specific steps: The heat exchange tube part model of the gas-liquid matching heat exchanger is constructed, and the heat exchange tube part model is divided into a plurality of micro-segments; based on the set inlet dryness, each micro-segment is divided into a two-phase segment and a superheated segment, specifically: the micro-segment with the inlet dryness less than 1 is divided into the two-phase segment, and the micro-segment with the inlet dryness equal to 1 is divided into the superheated segment; For each micro-segment: If it is the two-phase segment, the heat exchange amount of the working medium in the micro-segment is calculated; the outlet dryness of the heat exchange tube is iteratively calculated according to the heat exchange amount, and the pressure drop and the outlet pressure of the micro-segment are further calculated, and the specific steps are as follows: Assume the outlet dryness of the microelement section is: wherein: x i,out,a is the exit dryness assumed for the i-th elemental segment, x i,in is the inlet dryness of the i-th elemental segment; The average dryness of the inlet and outlet determines the working medium properties, and the average dryness of the i-th micro-element section is calculated x i : The heat flux is calculated from the inlet and outlet dryness q is: wherein, G is the refrigerant flow rate, Δ H is the latent heat of the refrigerant, D is the outer diameter of the heat exchange tube, L i is the length of the micro-element section of the heat exchange tube, and mesh is the number of micro-element sections; The refrigerant-side heat transfer coefficient of the two-phase section is calculated by a heat transfer correlation h r1 and the outside tube-side heat transfer coefficient h a1 The total thermal resistance UA is further calculated wherein, d is the inner diameter of the heat exchange tube, λ is the heat conduction coefficient of the heat exchange tube wall surface; The heat transfer unit number NTU is further calculated: wherein, C min Cp is the specific heat capacity of the fluid in the pipe, both inside and outside the pipe. The heat transfer effectiveness ε is calculated: Theoretical maximum heat exchange amount Q max : wherein, T a,dry,in is the air-side dry-bulb temperature, T i,in is the microelement segment refrigerant inlet temperature; The heat exchange amount of the microelement section under the assumption of the export dryness is calculated according to ε Q i And the corresponding export dryness x i,out,c : It is judged whether the assumed outlet dryness and the calculated outlet dryness converge: If not converged, the calculated exit dryness x i,out,c The exit dryness as a new assumption x i,out,a , return to the step of calculating the average dryness of the i-th microelement section, and repeat the iteration until convergence; If converged, the pressure drop of the micro-element, Δp, is calculated from the two-phase flow pressure drop correlation P i and the outlet pressure of the micro-element, pout P i,out The outlet conditions are taken as the inlet conditions for the next micro-element. The outlet pressure, flow rate and dryness are taken as the inlet conditions of the next micro-segment for the calculation of the next micro-segment; If it is the superheated segment, the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop and outlet pressure of the micro-segment are calculated, and the outlet pressure, flow rate and temperature are taken as the inlet conditions of the next micro-segment for the calculation of the next micro-segment; The heat exchange amount, pressure drop and outlet dryness of the heat exchange tube under different inlet flow rates and dryness are fitted into a database.

2. The method of data fitting of heat transfer tubes of a gas-liquid matching heat exchanger according to claim 1, characterized in that: The heat exchange tube part model of the gas-liquid matching heat exchanger is constructed, and the specific steps are as follows: The heat exchange tube structure parameters including tube length, tube number, tube spacing, outer diameter, inner diameter and thermal conductivity are obtained; If it is an internally threaded tube, the number of grooves, groove bottom width, tooth height, tooth top angle and spiral angle are also obtained; If there are mounting fins outside, the input fin parameters are also obtained; The ε-NTU method is used to simulate the heat exchange tube segment, and a one-dimensional heat exchange tube part model is constructed.

3. The method of data fitting of heat transfer tubes of a gas-liquid matching heat exchanger according to claim 1, characterized in that: If it is the superheated segment, the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop and outlet pressure of the micro-segment are calculated, and the specific steps are as follows: The maximum heat exchange amount of the micro-segment is calculated: wherein, C r Cp,air is the specific heat capacity of air, C a Cp,air is the specific heat capacity of air, The heat transfer coefficient on the refrigerant side in the superheating section is calculated from a heat transfer correlation h r and the heat transfer coefficient on the outside of the tube h a and the total thermal resistance UA and the number of heat transfer units NTU are calculated The heat transfer effectiveness ε is calculated according to the ε-NTU correlation formula of the non-phase-change cross flow: The heat exchange amount under the assumed export dryness is calculated from ε Q i and the export temperature: The pressure drop of the micro-element is calculated according to the pressure drop correlation of superheated section P i and the outlet pressure of the micro-element P i,out The outlet condition is taken as the inlet condition of the next micro-element.

4. The method of data fitting of a heat transfer tube of a gas-liquid matching heat exchanger according to claim 3, characterized in that: The heat exchange amount, pressure drop and outlet dryness of the heat exchange tube under different inlet flow rates and dryness are fitted into a database, and the specific steps are as follows: the flow range is divided into a plurality of flow rates according to the set step length, the heat exchange amount, pressure drop and outlet dryness of each flow rate at a plurality of inlet dryness are calculated, the relationship between the pressure drop and the flow rate at each inlet dryness, and the relationship between the outlet dryness and the flow rate are fitted, and the fitted correlation formula is taken as the database.

5. A simulation method of a gas-liquid matching heat exchanger, characterized in that: The data fitting method of the heat exchange tube according to any one of claims 1-4, comprising the following specific steps: The header part model of the gas-liquid matching heat exchanger is constructed; The flow in the header is simulated by using three-dimensional fluid mechanics calculation, and the simulation of the gas-liquid matching heat exchanger is realized: the outlet flow rate and dryness of the inlet header are monitored each time, the outlet dryness and the pressure drop of the heat exchange tube after heat exchange in the database are called according to the outlet flow rate and dryness of the inlet header, the outlet flow rate and the outlet dryness are taken as the inlet conditions of the outlet header, and the inlet pressure of the outlet header is monitored, and the pressure drop of the heat exchange tube is added to the inlet pressure as the outlet pressure of the inlet header.

6. The method of simulating a gas-liquid crossover heat exchanger of claim 5, wherein: When modeling the header part of the gas-liquid distribution heat exchanger, a three-dimensional physical model including several headers is constructed; for the three-dimensional physical model of each header, a structured grid is divided, and if the header part has a perforated plate, the grid at the distribution hole of the perforated plate is encrypted.

7. The method of simulating a gas-liquid crossover heat exchanger according to claim 6, wherein: The flow in the header is simulated by using three-dimensional fluid mechanics calculation to realize the simulation of the gas-liquid distribution heat exchanger, specifically, the inlet header and the outlet header are put into the same case for simulation by using ANSYS fluent software, and the flow and heat exchange of the heat exchange tube are replaced by using a user-defined equation UDF; in ANSYS fluent, the inlet header uses a velocity inlet boundary condition, and the outlet header uses a pressure outlet boundary condition; when the UDF is used to replace the heat exchange tube, the outlet parameter of the inlet header is monitored, and the heat transfer and pressure drop are calculated based on the database to obtain the outlet parameter of the heat exchange tube as the inlet condition of the outlet header, the inlet pressure of the outlet header is monitored, and the pressure drop of the heat exchange tube is added as the outlet pressure boundary condition of the inlet header based on the database.

8. A gas-liquid matching heat exchanger simulation system, characterized in that: The simulation method for the gas-liquid distribution heat exchanger according to any one of claims 5-7 comprises a modeling module, a heat exchange tube simulation module, a database fitting module, and a gas-liquid distribution heat exchanger simulation module: The modeling module is used to construct a heat exchange tube part model and a header part model of the gas-liquid distribution heat exchanger. The heat exchange tube simulation module is used to divide the heat exchange tube part model into several micro-segments; based on the set inlet quality, each micro-segment is divided into a two-phase segment and a superheated segment; for each micro-segment: if it is a two-phase segment, the heat exchange amount of the working medium in the micro-segment is calculated; the outlet quality of the heat exchange tube is iteratively calculated according to the heat exchange amount, and the pressure drop and outlet pressure of the micro-segment are further calculated; the outlet pressure, flow rate, and quality are used as the inlet conditions of the next micro-segment for the calculation of the next micro-segment; if it is a superheated segment, the maximum heat exchange amount, thermal resistance, heat exchange amount, outlet temperature of the working medium, pressure drop, and outlet pressure of the micro-segment are calculated, and the outlet pressure, flow rate, and temperature are used as the inlet conditions of the next micro-segment for the calculation of the next micro-segment. The database fitting module is used to fit the heat exchange amount, pressure drop, and outlet quality of the heat exchange tube under different inlet flow rates and qualities into a database. The gas-liquid distribution heat exchanger simulation module is used to simulate the flow in the header by using three-dimensional fluid mechanics calculation to realize the simulation of the gas-liquid distribution heat exchanger: the outlet flow rate and quality of the inlet header are monitored each time, the outlet quality and pressure drop of the heat exchange tube after heat exchange are called from the database according to the outlet flow rate and quality of the inlet header, the outlet flow rate and quality are used as the inlet conditions of the outlet header, and the inlet pressure of the outlet header is monitored, and the pressure drop of the heat exchange tube is added as the outlet pressure of the inlet header.

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