CN113188352A - Efficient compact heat exchanger and heat exchange amount calculation method - Google Patents

Efficient compact heat exchanger and heat exchange amount calculation method Download PDF

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Publication number
CN113188352A
CN113188352A CN202110528512.5A CN202110528512A CN113188352A CN 113188352 A CN113188352 A CN 113188352A CN 202110528512 A CN202110528512 A CN 202110528512A CN 113188352 A CN113188352 A CN 113188352A
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cold fluid
heat exchanger
hot
cold
hot fluid
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CN113188352B (en
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李冲
方贤德
罗祖分
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/06—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
    • F28F13/12—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media by creating turbulence, e.g. by stirring, by increasing the force of circulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/22—Arrangements for directing heat-exchange media into successive compartments, e.g. arrangements of guide plates
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/22—Arrangements for directing heat-exchange media into successive compartments, e.g. arrangements of guide plates
    • F28F2009/222—Particular guide plates, baffles or deflectors, e.g. having particular orientation relative to an elongated casing or conduit
    • F28F2009/224—Longitudinal partitions
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/08—Thermal analysis or thermal optimisation

Abstract

The invention discloses a high-efficiency compact heat exchanger and a heat exchange amount calculation method, wherein the high-efficiency compact heat exchanger comprises the following components: the device comprises a hot fluid inlet, a thermometer, a flowmeter, a flange end cover, a heat exchanger shell, a cold fluid inlet, a positive displacement air compressor, a cold fluid outlet, a hot fluid partition plate, a cold fluid baffle plate, a copper tube, a cold fluid ejector, a sealing cavity, an exhaust fan, a sealing plate, a vortex generator, a fastening nut, a hot fluid inlet pipeline, a hot fluid outlet pipeline, a cold fluid inlet pipeline and a cold fluid outlet pipeline; the heat exchanger has the advantages of compact structure and high heat exchange efficiency, and the heat exchange quantity calculation method has the advantages of simple calculation process, simple formula form, strong universality and high calculation accuracy.

Description

Efficient compact heat exchanger and heat exchange amount calculation method
Technical Field
The invention belongs to the technical field of general thermal equipment, and particularly relates to an efficient compact heat exchanger and a heat exchange quantity calculation method.
Background
The heat exchanger is also called a heat exchanger, is equipment for transferring heat from one medium to another medium, and is widely applied to various fields of aerospace, refrigeration, air conditioning, chemical engineering, energy, machinery, traffic and the like. However, the heat exchange quantity of the heat exchanger determines that the heat exchanger should meet certain heat exchange efficiency requirements. Therefore, the type and the flowing mode of the flowing medium in the heat exchanger, the core body structure of the heat exchanger and the heat exchange amount calculation method are key links for detecting whether the design of the heat exchanger and the heat exchange amount calculation result meet the requirements or not. The existing heat exchanger only adopts a fan to force a medium-cold fluid to flow, and the speed of the single forced flow mode is lower; the red copper tube in the existing heat exchanger core body structure is not internally provided with a structure which causes turbulent flow of hot fluid, so that the heat exchange coefficient of the fluid inside and outside the tube is low and the heat exchange is uneven; the method for calculating heat exchange quantity of the existing heat exchanger is to know core structure and size parameters of the heat exchanger, calculate air circulation area, air windward area, hot side hole degree, heat transfer area (heat conduction area of a partition plate and a round pipe), thermophysical property parameters, convection surface heat transfer coefficient, total heat transfer coefficient and heat transfer unit number, calculate heat exchanger efficiency and hot/cold fluid outlet temperature according to the solved parameters, and finally calculate the heat exchanger of the heat exchanger. The heat exchange quantity calculation method is only suitable for the heat exchanger with the known heat exchanger core body structure, and the calculation process is complex.
Therefore, how to design an efficient compact heat exchanger and a heat exchange amount calculation method to improve the heat exchange efficiency of the heat exchanger and simplify the heat exchange amount calculation process is a content of deep research needed by researchers in various regions.
Disclosure of Invention
In view of the above-mentioned deficiencies of the prior art, the present invention aims to provide a high-efficiency compact heat exchanger and a heat exchange amount calculation method, which not only make the heat exchanger have the advantages of compact structure and high heat exchange efficiency, but also make the heat exchange amount calculation method have the advantages of simple calculation process, simple formula form, strong versatility and high calculation accuracy.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: in one aspect, the present invention provides a high efficiency compact heat exchanger comprising: the device comprises a hot fluid inlet, a thermometer, a flowmeter, a flange end cover, a heat exchanger shell, a cold fluid inlet, a positive displacement air compressor, a cold fluid outlet, a hot fluid partition plate, a cold fluid baffle plate, a copper tube, a cold fluid ejector, a sealing cavity, an exhaust fan, a sealing plate, a vortex generator, a fastening nut, a hot fluid inlet pipeline, a hot fluid outlet pipeline, a cold fluid inlet pipeline and a cold fluid outlet pipeline; the bottom of the thermometer is respectively embedded in the hot fluid inlet pipeline, the hot fluid outlet pipeline, the cold fluid inlet pipeline and the cold fluid outlet pipeline, the bottom of the flowmeter is respectively embedded in the hot fluid inlet pipeline and the cold fluid inlet pipeline, and the tops of the thermometer and the flowmeter are exposed outside the corresponding pipelines; the hot fluid inlet pipeline and the hot fluid outlet pipeline are connected with flange end covers in a screwed mode, the cold fluid inlet pipeline and the cold fluid outlet pipeline are connected with the heat exchanger shell in a screwed mode, the flange end covers are fixed on the heat exchanger shell through fastening nuts, and through holes matched with the nuts are formed in the heat exchanger shell; the inner cavity of the shell of the heat exchanger is welded with the outer wall of the sealing plate, and the sealing plates are vertically and fixedly connected with each other; the positive displacement air compressing device is fixed on the cold fluid inlet pipeline through a bolt, a through hole matched with the bolt is formed in the cold fluid inlet pipeline, and the cold fluid ejector is in interference fit with the cold fluid inlet pipeline; the hot fluid baffle is fixedly connected with the flange end cover, the heat exchanger shell and the cold fluid baffle, the cold fluid baffle is welded with the sealing plate at uniform intervals, and the red copper pipe is in interference fit with the through hole in the cold fluid baffle; the vortex generator is suspended in the red copper pipe and is fixedly connected with the red copper pipe through extension rods at two ends of the vortex generator; the exhaust fan is embedded in the cold fluid outlet pipeline through the groove.
Furthermore, the bottoms of the thermometer and the flowmeter are sequentially embedded in the hot fluid inlet pipeline and the cold fluid inlet pipeline along the flowing direction of the hot fluid and the cold fluid.
Further, the positive displacement compressor includes: the device comprises a telescopic rod, an upward baffle, a cold fluid container, a piston, a hydraulic rod, a hydraulic cylinder, an air compressing device pipeline, a circular flat plate and a downward pressing stop block, wherein the bottom of the telescopic rod is fixedly connected with the air compressing device pipeline, the top of the telescopic rod is connected with the upward baffle or the downward pressing stop block in a screwing mode, the cold fluid container realizes the circulation of cold fluid through the upward movement of the upward baffle and the downward pressing action of the downward pressing stop block, and the circular flat plate is fixedly connected to the middle position of the air compressing device pipeline along the radial direction.
Furthermore, the cold fluid baffle is in a structure like a Chinese character 'ji' and is welded on the inner wall of the sealing plate at uniform intervals, the side faces of the cold fluid baffles on the two sides in the thickness direction are welded with the inner wall of the sealing plate, and only three faces of the cold fluid baffle in the middle in the thickness direction are welded with the inner wall of the sealing plate.
Furthermore, the cold fluid injector nozzle is of an outward expansion structure, and a gap is formed between the cold fluid injector nozzle and the copper tube.
Further, the vortex generator is of a double-spiral structure.
Furthermore, the size of the cross section of the sealing cavity is the same as that of the outer wall of the sealing plate, and the sealing cavity is communicated with the hot fluid inlet pipeline and the hot fluid outlet pipeline.
On the other hand, the invention provides a heat exchange amount calculation method, which specifically comprises the following steps: the method utilizes the efficient compact heat exchanger to calculate heat exchange efficiency and heat exchange quantity according to actually measured inlet and outlet parameters, thereby establishing a database for solving parameters related to heat exchange efficiency values, and establishing a mean value model with simple heat exchange quantity calculation process, simple calculation formula and high calculation precision by combining a Matlab iterative optimization program and 1stOpt curve analysis software.
The invention has the beneficial effects that:
1. the volume type air compressing device enables cold fluid entering a cold fluid inlet pipeline to obtain certain kinetic energy by reducing the volume of cold fluid gas at a cold fluid inlet and increasing the air quality per unit volume, and the cold fluid with certain kinetic energy is ejected out according to a certain outward expansion angle by using a cold fluid ejector, so that the flowing speed of the cold fluid can be effectively improved, and the heat/cold fluid convection heat transfer coefficient and the heat conductivity coefficient can be increased.
2. The heat exchanger core body heat exchange structure adopts a shell-and-tube multi-flow cross flow heat exchange structure, cold fluid flows in a shape like a Chinese character 'ji' along a cold fluid partition plate, hot fluid flows in the axial direction of a red copper tube, and the heat exchange structure is simple and good in heat exchange effect.
3. When the hot fluid flows axially along the inner part of the red copper pipe, the vortex generator in the red copper pipe disturbs the flow of the hot fluid, and the heat exchange coefficient of the core body structure of the heat exchanger is increased.
4. Compared with the heat exchange quantity calculation method of the traditional heat exchanger, the heat exchange quantity calculation method of the heat exchanger is characterized in that corresponding different heat exchanger efficiency values are calculated by utilizing different sets of inlet and outlet parameter (fluid temperature and mass flow) values which are actually measured, so that a database for solving relevant parameters of the heat exchange efficiency values is established, and a polynomial of a heat exchange efficiency calculation formula only related to the mass flow of hot and cold fluids is established by combining a Matlab iterative optimization program and 1stOpt curve analysis software, so that the heat exchange quantity of the heat exchanger is calculated. The calculation method does not need to calculate the parameters such as air circulation area, air windward area, hot side hole degree, heat transfer area (heat transfer area of the partition plate and the circular tube), thermophysical parameters, convection surface heat transfer coefficient, total heat transfer coefficient, heat transfer unit number and the like, and is suitable for the condition that the core structure of the heat exchanger is unknown.
Drawings
FIG. 1 is a sectional view showing the overall structure of a high-efficiency compact heat exchanger and a heat exchange amount calculating method according to the present invention
FIG. 2 is a schematic diagram of the overall structure of the high-efficiency compact heat exchanger and the heat exchange amount calculation method of the invention
FIG. 3 is a schematic view of the heat exchanger core structure of the present invention
FIG. 4 is a schematic view of the vortex generator of the present invention
Fig. 5a and 5b are schematic views of the positive displacement compressor of the present invention
In the figure: the device comprises a hot fluid inlet 1, a thermometer 2, a flowmeter 3, a flange end cover 4, a heat exchanger shell 5, a cold fluid inlet 6, a positive displacement air compressing device 7, a cold fluid outlet 8, a hot fluid outlet 9, a hot fluid partition plate 10, a cold fluid baffle plate 11, a copper tube 12, a cold fluid ejector 13, a seal cavity 14, an exhaust fan 15, a seal plate 16, a vortex generator 17, a fastening nut 18, a hot fluid inlet pipeline 19, a hot fluid outlet pipeline 20, a cold fluid inlet pipeline 21, a cold fluid outlet pipeline 22, a telescopic rod 71, an upward lifting baffle plate 72, a cold fluid container 73, a piston 74, a hydraulic rod 75, a hydraulic cylinder 76, an air compressing device pipeline 77, a round flat plate 78 and a downward pressing stop block 79.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-5 b, the present embodiment provides a high-efficiency compact heat exchanger, comprising: the device comprises a hot fluid inlet 1, a thermometer 2, a flowmeter 3, a flange end cover 4, a heat exchanger shell 5, a cold fluid inlet 6, a positive displacement air compressing device 7, a cold fluid outlet 8, a hot fluid outlet 9, a hot fluid partition plate 10, a cold fluid baffle plate 11, a copper tube 12, a cold fluid ejector 13, a sealing cavity 14, an exhaust fan 15, a sealing plate 16, a vortex generator 17, a fastening nut 18, a hot fluid inlet pipeline 19, a hot fluid outlet pipeline 20, a cold fluid inlet pipeline 21 and a cold fluid outlet pipeline 22. It should be noted that, in this embodiment, the core structure of the heat exchanger adopts a shell-and-tube multi-flow cross-flow heat exchange structure.
Specifically, in this embodiment, the number of the thermometers 2 is 4, the bottoms of the 4 thermometers 2 are respectively embedded in the hot fluid inlet pipeline 19, the hot fluid outlet pipeline 20, the cold fluid inlet pipeline 21 and the cold fluid outlet pipeline 22, the number of the flow meters 3 is 2, the bottoms of the flow meters 3 are respectively embedded in the hot fluid inlet pipeline 19 and the cold fluid inlet pipeline 21, and the tops of the thermometers 2 and the flow meters 3 are both exposed outside the corresponding pipelines; the hot fluid inlet pipeline 19 and the hot fluid outlet pipeline 20 are in screwed connection with the flange end cover 4, the cold fluid inlet pipeline 21 and the cold fluid outlet pipeline 22 are in screwed connection with the heat exchanger shell 5, the flange end cover 4 is fixed on the heat exchanger shell 5 through a fastening nut 18, and a through hole matched with the nut is formed in the heat exchanger shell 5; the inner cavity of the heat exchanger shell 5 is welded with the outer wall of the sealing plate 16, and 4 sealing plates 16 are vertically and fixedly connected with each other; the positive displacement air compressing device 7 is fixed on a cold fluid inlet pipeline 21 through a bolt, a through hole matched with the bolt is formed in the cold fluid inlet pipeline 21, and the cold fluid ejector 13 is in interference fit with the cold fluid inlet pipeline 21; the hot fluid baffle plate 10 is fixedly connected with the flange end cover 4, the heat exchanger shell 5 and the cold fluid baffle plate 11, the cold fluid baffle plate 11 is welded with the sealing plate at uniform intervals, and the copper tube 12 is in interference fit with a through hole on the cold fluid baffle plate 11; in this embodiment, the cold fluid baffles 11 are welded on the inner wall of the sealing plate 16 at uniform intervals in a zigzag structure, wherein the side surfaces of the cold fluid baffles 11 on the two sides in the thickness direction are welded with the inner wall of the sealing plate 16, and only three surfaces of the cold fluid baffles 11 in the middle in the thickness direction are welded with the inner wall of the sealing plate 16. The cold fluid is accelerated to flow along the cold fluid partition plate in a reversed V shape under the suction action of the exhaust fan, so that the convection heat transfer coefficient and the heat conduction coefficient are improved. The hot fluid flows axially along the inner part of the red copper pipe, and after flowing to the sealing cavity, the hot fluid moves upwards along the sealing cavity under the action of molecular heat movement to enter the red copper pipe communicated with the hot fluid outlet pipeline, and in the flowing process of the hot fluid, the vortex generator in the red copper pipe generates disturbance to the flow of the hot fluid, so that the heat exchange coefficient of the core body structure of the heat exchanger is increased.
Further, the vortex generator 17 is suspended in the copper tube 12 and is fixedly connected with the copper tube 12 through extension rods at two ends of the vortex generator 17; referring to fig. 4, in the present embodiment, the vortex generator 17 has a double spiral structure.
Further, the exhaust fan 15 is embedded in the cold fluid outlet pipe 22 through a groove.
Specifically, referring to fig. 5a and 5b, the positive displacement air compressing device 7 includes an extendable rod 71, an uplift baffle 72, a cold fluid container 73, a piston 74, a hydraulic rod 75, a hydraulic cylinder 76, an air compressing device pipeline 77, a circular flat plate 78 and a downward pressing stopper 79, the bottom of the extendable rod 71 is fixedly connected with the air compressing device pipeline 77, the top of the extendable rod 71 is rotatably connected with the uplift baffle 72 or the downward pressing stopper 79, the cold fluid container 73 realizes the circulation of cold fluid through the uplift action of the uplift baffle 72 and the downward pressing action of the downward pressing stopper 79, and the circular flat plate 78 is fixedly connected to the middle position of the air compressing device pipeline 77 along the radial direction.
Further, the cold fluid injector 13 nozzle is of an outward expansion structure, and a gap is formed between the cold fluid injector 13 nozzle and the copper tube 12.
Further, the cross-sectional area of the sealing chamber 14 is the same as that of the outer wall of the sealing plate 16, and the sealing chamber is communicated with a hot fluid inlet pipe 19 and a hot fluid outlet pipe 20.
The cold fluid enters the positive displacement air compressing device from the cold fluid inlet, the telescopic rod connected with the upper lifting stop block extends under the action of the cold fluid pressure, the upper lifting stop block moves towards the direction far away from the bottom of the telescopic rod, and the cold fluid enters the cold fluid container along the gap between the upper lifting stop block and the cold fluid container. At the moment, the hydraulic rod extends to compress the volume of cold fluid entering the cold fluid container, the telescopic rod connected with the pressing stop block is compressed, and the pressing stop block moves towards the direction close to the bottom of the telescopic rod, so that the volumetric air compression device increases the mass of air per unit volume by reducing the volume of cold fluid gas at a cold fluid inlet, so that the cold fluid entering a cold fluid inlet pipeline obtains certain kinetic energy, and the cold fluid with certain kinetic energy is sprayed out by using a cold fluid sprayer according to a certain outward expansion angle, so that the flow speed of the cold fluid can be effectively improved, and the heat/cold fluid convection heat transfer coefficient and the heat conductivity coefficient can be increased.
In this embodiment, the heat exchange amount calculation method is calculated based on the efficient compact heat exchanger, and specifically, the heat exchange amount calculation method obtains the inlet temperature T of the hot fluid by installing a thermometer and a flowmeterhinHot fluid outlet temperature ThoutInlet mass flow of hot fluid GhCold fluid inlet temperature TcinCold fluid outlet temperature TcoutMass flow G of cold fluid inletcThrough the measured inlet temperature value T of the hot fluidhinHot fluid outlet temperature value ThoutCold fluid inlet temperature value TcinCold fluid outlet temperature value Tcout。
The arithmetic mean temperatures of the hot fluid and the cold fluid can be obtained by the equations (1) and (2), respectively.
Figure BDA0003066307940000061
Figure BDA0003066307940000062
Calculating the constant pressure specific heat c of the hot fluid and the cold fluid by the formula (3) according to the calculated arithmetic mean temperature of the hot fluid and the cold fluidp。
Figure BDA0003066307940000063
The heat capacities on the hot fluid side and the cold fluid side, the minimum heat capacity, and the heat capacity ratio were obtained by equations (4) to (7).
Ch＝Ghcp (4)
Cc＝Gccp (5)
Cmin＝(Ch,Cc) (6)
Figure BDA0003066307940000071
And (4) respectively calculating the efficiency value of the one-way cross flow type heat exchanger, the total efficiency value of the heat exchanger and the heat exchange quantity of the heat exchanger by using the formulas (8) to (10), wherein the calculated parameters are collectively called experimental values.
Figure BDA0003066307940000072
Figure BDA0003066307940000073
φ＝εCmin(thin-thout) (10)
The efficiency formula of the single-pass cross-flow heat exchanger is expressed in the form of formula (11) due to the constant pressure specific heat c of airpAnd Pr vary little with temperature, equations (7) and (12) can be rewritten as equations (13) and (14), and therefore, the one-way cross-flow heat exchanger efficiency equation can be written as equation (15).
Figure BDA0003066307940000074
Figure BDA0003066307940000075
Figure BDA0003066307940000076
Figure BDA0003066307940000077
Figure BDA0003066307940000081
Wherein AU represents the total heat transfer coefficient; NTU represents the number of heat transfer units; gmaxIndicating the greater of the hot and cold fluid inlet mass flows, i.e. when Gh>GcWhen, Gmax＝GhOtherwise Gmax＝Gc；GminIndicating the lesser of the inlet mass flows of the hot and cold fluids, i.e. when Gh>GcWhen, Gmin＝GcOtherwise Gmin＝Gh。
Referring to Dittus-Boelter equation, and considering that Pr varies little with temperature, there are
Figure BDA0003066307940000082
In the formula, a is a predetermined constant, and in the Dittus-Boelter formula, a is 0.8. However, studies have shown that a is not a constant number for different ranges of Re numbers. So a piecewise fitting a according to G/μ is considered.
Total heat transfer coefficient of hot side (Ah)h＝HhTotal heat transfer coefficient of cold edge (Ah)c＝Hc，
Figure BDA0003066307940000083
Further, AU can be simplified to the formula (16), the formula (17) and
Figure BDA0003066307940000084
because when a is about 0.8 and the temperature change of the ring-controlled cold side is in the range,
Figure BDA0003066307940000085
the variation with temperature is small, so the formula (18) can be simplified to
Figure BDA0003066307940000086
Combining formula (15) with formula (19) to obtain
Figure BDA0003066307940000087
Wherein a is determined by the size of G and a is3And a4Should be around 0.8, a5Around 0.22. If G ishAnd GcIs different because of GhAnd GcThe size ranges are greatly different if GhAnd GcA little difference in size, a3And a4Should be equal.
Calculating the efficiency value of the one-way cross-flow heat exchanger obtained by the formula (8) and the corresponding valueGh、GcSubstituting the value into the formula (20), and combining a Matlab iterative optimization program and 1stOpt curve analysis software to obtain a constant a to be determined1～a5The final form of equation (20) can be determined. When recalculating next time, only G needs to be calculatedh、GcThe value is substituted into the formula (20) to obtain the efficiency value of the one-way cross flow type heat exchanger which is theoretically calculated, the efficiency value of the one-way cross flow type heat exchanger which is theoretically calculated is substituted into the formula (9), the total efficiency value of the heat exchanger is obtained, finally, the heat exchange quantity of the heat exchanger is calculated by using the formula (10), and the calculated parameters are collectively called as calculated values.
The approximation degree of the predicted value (calculated value) of the model to the experimental value is evaluated by using the mean Absolute error MAD (mean Absolute deviation development), and the accuracy of the predicted value (calculated value) is higher as the MAD is smaller, as shown in the formula (21).
Figure BDA0003066307940000091
The mean Relative error mrd (mean Relative development) is used to determine the deviation of the model predicted value from the experimental value, as shown in equation (22).
Figure BDA0003066307940000092
The efficiency formula of the one-way cross flow heat exchanger obtained by fitting only contains Gh、GcThe two unknown parameters are adopted, so that the method for calculating the heat exchange quantity of the heat exchanger only needs to know the mass flow of the hot/cold fluid and does not need to know the structural parameters of the core body of the heat exchanger, the parameters used for calculation can be greatly reduced, the calculation process is simpler, the calculation formula is simpler, the universality is higher, and the calculation accuracy is higher.
Wherein the unit of the temperature T is K, the unit of the temperature T is DEG C, the unit of the mass flow G is kg/s, and the unit of the specific heat c at constant pressurepThe unit of (A) is J/(kg K), the unit of heat exchange amount phi is J, the unit of total heat transfer coefficient AU is W/K, the unit of dynamic viscosity mu is Pa · s, the unit of thermal conductivity coefficient lambda is W/m K,n represents the number of hot flow paths × the number of cold flow paths, pre represents a predicted value (theoretically calculated value), and exp represents an experimental value.
An exemplary flow chart of a method for implementing a service chain according to an embodiment of the present invention is described above with reference to the accompanying drawings. It should be noted that the numerous details included in the above description are merely exemplary of the invention and are not limiting of the invention. In other embodiments of the invention, the method may have more, fewer, or different steps, and the order, inclusion, function, etc. of the steps may be different from that described and illustrated.

Claims (10)

1. A high efficiency compact heat exchanger comprising: the device comprises a hot fluid inlet (1), a thermometer (2), a flowmeter (3), a flange end cover (4), a heat exchanger shell (5), a cold fluid inlet (6), a positive displacement air compressing device (7), a cold fluid outlet (8), a hot fluid outlet (9), a hot fluid partition plate (10), a cold fluid baffle plate (11), a copper tube (12), a cold fluid ejector (13), a seal cavity (14), an exhaust fan (15), a seal plate (16), a vortex generator (17), a fastening nut (18), a hot fluid inlet pipeline (19), a hot fluid outlet pipeline (20), a cold fluid inlet pipeline (21) and a cold fluid outlet pipeline (22); the bottom of the thermometer (2) is respectively embedded in a hot fluid inlet pipeline (19), a hot fluid outlet pipeline (20), a cold fluid inlet pipeline (21) and a cold fluid outlet pipeline (22), the bottom of the flowmeter (3) is respectively embedded in the hot fluid inlet pipeline (19) and the cold fluid inlet pipeline (21), and the tops of the thermometer (2) and the flowmeter (3) are exposed outside the corresponding pipelines; the hot fluid inlet pipeline (19) and the hot fluid outlet pipeline (20) are in screwed connection with the flange end cover (4), the cold fluid inlet pipeline (21) and the cold fluid outlet pipeline (22) are in screwed connection with the heat exchanger shell (5), the flange end cover (4) is fixed on the heat exchanger shell (5) through a fastening nut (18), and a through hole matched with the nut is formed in the heat exchanger shell (5); the inner cavity of the heat exchanger shell (5) is welded with the outer wall of the sealing plate (16), and the sealing plates (16) are vertically and fixedly connected with each other; the positive displacement air compressing device (7) is fixed on a cold fluid inlet pipeline (21) through bolts, a through hole matched with the bolts is formed in the cold fluid inlet pipeline (21), and the cold fluid ejector (13) is in interference fit with the cold fluid inlet pipeline (21); the hot fluid baffle (10) is fixedly connected with the flange end cover (4), the heat exchanger shell (5) and the cold fluid baffle (11), the cold fluid baffle (11) is welded with the sealing plate at uniform intervals, and the red copper tube (12) is in interference fit with a through hole on the cold fluid baffle (11); the vortex generator (17) is suspended in the red copper tube (12) and is fixedly connected with the red copper tube (12) through extension rods at two ends of the vortex generator (17); the exhaust fan (15) is embedded in the cold fluid outlet pipeline (22) through a groove.
2. The efficient and compact heat exchanger according to claim 1, wherein the bottom of the thermometer (2) and the flowmeter (3) are embedded in the hot fluid inlet pipe (19) and the cold fluid inlet pipe (21) in sequence along the flow direction of the hot and cold fluids.
3. The efficient and compact heat exchanger according to claim 1, wherein the volumetric air compressing device (7) comprises an extensible rod (71), an upward-lifting baffle plate (72), a cold fluid container (73), a piston (74), a hydraulic rod (75), a hydraulic cylinder (76), an air compressing device pipeline (77), a circular plate (78) and a downward-pressing stop block (79), the bottom of the extensible rod (71) is fixedly connected with the air compressing device pipeline (77), the top of the extensible rod is rotatably connected with the upward-lifting baffle plate (72) or the downward-pressing stop block (79), the cold fluid container (73) realizes the circulation of cold fluid through the upward-lifting action of the upward-lifting baffle plate (72) and the downward-pressing action of the downward-pressing stop block (79), and the circular plate (78) is fixedly connected to the middle position of the air compressing device pipeline (77) along the radial direction.
4. The efficient compact heat exchanger according to claim 1, wherein the cold fluid baffles (11) are welded to the inner wall of the sealing plate (16) at uniform intervals in a zigzag structure, wherein the two sides of the cold fluid baffles (11) in the thickness direction are welded to the inner wall of the sealing plate (16), and only three sides of the middle cold fluid baffle (11) in the thickness direction are welded to the inner wall of the sealing plate (16).
5. The efficient and compact heat exchanger as recited in claim 1, wherein the nozzle of the cold fluid injector (13) is of an outward-expanding structure, and a gap is formed between the nozzle of the cold fluid injector (13) and the copper tube (12).
6. The efficient compact heat exchanger according to claim 1, characterized in that the vortex generator (17) is of double helix structure.
7. The efficient compact heat exchanger according to claim 1, characterized in that the sealing chamber (14) has a cross-sectional area equal to the cross-sectional area of the outer wall of the sealing plate (16) and communicates with the hot fluid inlet conduit (19) and the hot fluid outlet conduit (20).
8. A heat exchange amount calculation method is characterized by comprising the following steps:
measuring inlet and outlet parameters of hot fluid and cold fluid by using the efficient compact heat exchanger of any one of claims 1-7;
determining the efficiency value of the experimental single-pass cross-flow heat exchanger, the total efficiency value of the experimental heat exchanger and the heat exchange quantity of the experimental heat exchanger according to the inlet and outlet parameters;
substituting the efficiency value of the experimental one-way cross flow heat exchanger, the total efficiency value of the experimental heat exchanger and the heat exchange quantity of the experimental heat exchanger into a formula (20), and calculating a constant a to be determined by combining a Matlab iterative optimization program and 1stOpt curve analysis software1～a5To determine the final form of equation (20)
Figure FDA0003066307930000021
Determining the efficiency value of the theoretically-calculated one-way cross-flow heat exchanger according to the determined final form of the formula (20), the mass flow of the hot fluid inlet and the mass flow of the cold fluid inlet to be calculated, determining the total efficiency value of the theoretically-calculated heat exchanger according to the efficiency value of the theoretically-calculated one-way cross-flow heat exchanger, and finally calculating the heat exchange quantity of the heat exchanger according to the total efficiency value of the theoretically-calculated heat exchanger;
in the formula, exp represents the experimentValue, GmaxRepresenting the greater of the hot and cold fluid inlet mass flows; gminRepresenting the lesser of the inlet mass flows of the hot and cold fluids, GhRepresents the hot fluid inlet mass flow; gcRepresenting the cold fluid inlet mass flow; a is1～a5Indicating the undetermined constant.
9. The heat exchange amount calculation method according to claim 8, wherein the parameter includes an inlet temperature ThinHot fluid outlet temperature ThoutInlet mass flow of hot fluid GhCold fluid inlet temperature TcinCold fluid outlet temperature TcoutMass flow G of cold fluid inletcThrough the measured inlet temperature value T of the hot fluidhinHot fluid outlet temperature value ThoutCold fluid inlet temperature value TcinAnd a cold fluid outlet temperature value.
10. The method according to claim 8 or 9, wherein the determining an experimental once-through cross-flow heat exchanger efficiency value, an experimental heat exchanger total efficiency value, and an experimental heat exchanger heat exchange amount according to the inlet and outlet parameters further comprises:
the arithmetic mean temperature of the hot fluid and the cold fluid can be respectively obtained by using the formulas (1) and (2);
Figure FDA0003066307930000031
Figure FDA0003066307930000032
calculating the constant pressure specific heat c of the hot fluid and the cold fluid by the formula (3) according to the calculated arithmetic mean temperature of the hot fluid and the cold fluidp；
Figure FDA0003066307930000033
Obtaining heat capacities on the hot fluid side and the cold fluid side, a minimum heat capacity, and a heat capacity ratio by equations (4) to (7);
Ch＝Ghcp (4)
Cc＝Gccp (5)
Cmin＝(Ch,Cc) (6)
Figure FDA0003066307930000041
respectively calculating the efficiency value of the experimental once-through cross-flow heat exchanger, the total efficiency value of the experimental heat exchanger and the heat exchange quantity of the experimental heat exchanger by using the formulas (8) to (10);
Figure FDA0003066307930000042
Figure FDA0003066307930000043
φ＝εCmin(thin-thout) (10)
in the formula, ThavIs the arithmetic mean temperature of the hot fluid; t iscavIs the arithmetic mean temperature of the cold fluid; chA heat capacity on the side of the hot fluid; ccA heat capacity on the cold fluid side; cminA minimum heat capacity; gamma is the heat capacity ratio; epsiloniThe efficiency value of the experimental one-way cross flow heat exchanger is shown; epsilon is the total efficiency value of the experimental heat exchanger; phi is the heat exchange quantity of the experimental heat exchanger.
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