CN112857107A - Design method of wound tube type heat exchanger with shell side boiling tube side condensation - Google Patents

Design method of wound tube type heat exchanger with shell side boiling tube side condensation Download PDF

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CN112857107A
CN112857107A CN202110069205.5A CN202110069205A CN112857107A CN 112857107 A CN112857107 A CN 112857107A CN 202110069205 A CN202110069205 A CN 202110069205A CN 112857107 A CN112857107 A CN 112857107A
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shell
tube
section
heat exchange
boiling
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韩勇
吴学红
朱有健
王燕令
曹泷
张振亚
杨伟
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Zhengzhou University of Light Industry
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Zhengzhou University of Light Industry
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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
    • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes

Abstract

The invention discloses a design method of a wound tube heat exchanger with shell side boiling tube side condensation, wherein according to the bubble point and the dew point of a working medium, the shell side is divided into a liquid phase section and a boiling section, or the shell side is divided into a liquid phase section, a boiling section and a gas phase section, and corresponding sections are respectively designed and calculated to determine the heat exchange coefficient, the heat exchange quantity, the heat exchange area and the effective heat exchange length of each section; if the dryness of the outlet section is less than 1, the whole spiral wound tubular heat exchanger shell side is divided into two parts, namely a liquid phase section and a boiling section; if the dryness of the outlet is equal to 1, the whole spiral wound tubular heat exchanger shell side is divided into a liquid phase section, a boiling section and a gas phase section; the tube side condensation section has phase change, and the heat exchange coefficient is related to the dryness. The design method of the winding tube type heat exchanger provided by the invention has the characteristics of high calculation precision, complete design method, high calculation efficiency and the like, and has high commercial value and market popularization value.

Description

Design method of wound tube type heat exchanger with shell side boiling tube side condensation
Technical Field
The invention relates to the technical field of wound tube type heat exchangers, in particular to a design method of a wound tube type heat exchanger with shell pass boiling tube pass condensation.
Background
The coiled pipe type heat exchanger has the characteristics of large heat transfer area per unit volume, small floor area, high heat transfer coefficient, small heat transfer temperature difference, high heat transfer efficiency, high pressure resistance, self-compensation of thermal expansion, difficult scaling, easy realization of large-scale and the like, and also has the function of realizing simultaneous heat transfer of various media. The coiled pipe type heat exchanger is mainly applied to the industries of air separation, liquefied natural gas and the like. In recent years, with the large-scale development of petrochemical, coal chemical and liquefied natural gas devices, coiled heat exchangers have been used in large quantities due to their advantages of high heat transfer efficiency, compact structure and the like. For example, a hydrogenation reactor of a large oil refining device, a high-pressure material heat exchanger at the rear part of a reforming reactor of a PX device, a methanol washing heat exchanger in a coal-to-methanol device, and a reactor rear heat exchanger in a coal-to-ethylene glycol device all adopt a coiled tube heat exchanger to replace a traditional baffle plate type heat exchanger, a thread locking ring type heat exchanger and a plate shell type heat exchanger, so that the operation of high pressure resistance and zero leakage is realized. Therefore, the coiled pipe type heat exchanger has wide market prospect in the industries of petrochemical industry, coal chemical industry and the like.
The design and manufacture key technology of the thermodynamic process of the wound tube heat exchanger are complex. In the last decade, related enterprises in China adopt imitation, develop the heat exchanger and obtain industrial application. The process calculation of the heat exchanger is very complex, and relates to heat transfer processes of phase change, no phase change, single flow, multi-flow and the like. However, no mature forward design method exists in China so far, especially simple imitation reverse design, and the core competitiveness of the international level is not reached from the design level and the manufacturing capability. Therefore, the research and development of the thermal process design technology of the coiled heat exchanger have important practical significance in the aspects of academic research, engineering application, localization of important equipment and the like.
Disclosure of Invention
The invention provides a design method of a shell side boiling tube side condensed wound tube type heat exchanger, which has the advantages that the design method is provided with a forward design, relates to the field of shell side boiling of wound tubes, applies a high-precision heat exchange coefficient calculation formula, and improves the calculation control precision by adopting sectional calculation.
A design method of a wound tube heat exchanger with shell side boiling tube side condensation is characterized in that: according to the bubble point and the dew point of the working medium, the shell side is divided into a liquid phase section and a boiling section, or the shell side is divided into a liquid phase section, a boiling section and a gas phase section, and the design calculation is respectively carried out on the corresponding sections to determine the heat exchange coefficient, the pressure drop, the heat exchange quantity, the heat exchange area and the axial effective heat exchange length of the winding section of each section.
If the dryness of the outlet of the wound tube type heat exchanger is less than 1, the whole wound tube type heat exchanger is divided into two parts, namely a liquid phase section and a boiling section; if the outlet quality of the winding pipe type heat exchanger is equal to 1, the whole winding pipe type heat exchanger is divided into a liquid phase section, a boiling section and a gas phase section. Phase change exists in the tube side condensation section, and design calculation is carried out on the tube side condensation section in a sectional mode.
The bubble point temperature from the shell side inlet to the fluid working medium is a liquid phase section, the bubble point temperature from the fluid working medium to the dew point temperature is a boiling section, and the dew point temperature to the shell side outlet is a gas phase section.
Dividing the shell side into two (or three) parts according to the bubble point temperature, the dew point temperature, the outlet dryness, the outlet temperature and the like; the shell-side liquid phase section design calculation method can effectively and accurately calculate the heat exchange quantity, the heat exchange area, the effective heat exchange length and the like of the shell-side liquid phase section of the wound tube type heat exchanger.
Iterative calculation is required, and is realized by coupling the design method of the wound tube heat exchanger with the shell-side boiling tube-side condensation by means of a programming tool.
According to the design method of the shell-side boiling tube-side condensed wound tube type heat exchanger, the flow of the design method is that design calculation is started, and firstly, physical parameters of a working medium are input; in the second place, the first place is,inputting a designed rated working condition; thirdly, setting structural parameters according to design requirements; fourthly, dividing the shell side into a liquid phase section, a boiling section and a gas phase section according to the dew point temperature and the bubble point temperature of the working medium, and respectively calculating the heat exchange coefficients (h) corresponding to the three sectionsL、hTP(j) And hG) (ii) a Fifthly, calculating the tube pass condensation heat exchange coefficient in a segmented manner; sixthly, calculating the heat exchange area, the heat exchange quantity and the bubble point temperature position of the liquid phase section according to the heat balance; seventhly, calculating the heat exchange area, the heat exchange quantity and the dew point temperature position of the boiling section according to the heat balance; eighthly, calculating the heat exchange area and the heat exchange quantity of the gas phase section according to the heat balance; ninthly, adding the heat exchange quantities of the liquid phase section, the gas phase section and the boiling section, and accounting for the total heat exchange area AtotTotal heat exchange quantity QdesignThe total length E of the winding section, the bubble point temperature position and the dew point temperature position; tenth, calculate decision Q from the designdesign≥QloadIf the relation is not established, the structure is rearranged, and if the relation is established, the next step is carried out; eleventh, calculating a tube side pressure drop and a shell side pressure drop of the wound tube heat exchanger comprises: tube side pressure drop | Δ P $tp,tubeTotal pressure drop of shell pass | Δ Pdesign,shell,totShell side liquid phase section pressure drop | delta P utidesign,LShell side boiling phase section pressure drop | Δ P-tdesign,TPShell side gas phase section pressure drop | delta P-design,G(ii) a Twelfth, it is determined | Δ P |, by design calculationload,shell,tot≥|ΔP|design,shell,totAnd | Δ P ∞load,tube≥|ΔP|tp,tubeAnd if the two conditions are not satisfied simultaneously, rearranging the structure, and if the relational expression is satisfied, outputting the result.
Further, the physical parameters of the working medium in the first step comprise specific heat, thermal conductivity, density, dew point temperature and bubble point temperature of the working medium; the designed rated working conditions of the second step comprise: thermal load QloadShell side allowable voltage drop | delta P-load,shellTube pass allowable voltage drop | Δ P-load,tubeHeat exchange allowance and area allowance; the structural parameters in the third step include: 1-inner diameter of barrel, DB(ii) a 2-outer diameter of core barrel, DC(ii) a 3-spiral windingOutside diameter of the coil, do(ii) a 4-tube spacing of the same layer of wound tubes, SL(ii) a 5-wrap angle, ε; 6-total length of wound section, E; 7-inner layer winding diameter, Dco,1(ii) a 8-outer layer winding diameter, Dco,2(ii) a 9-helical winding pipe layer spacing, ST(ii) a 21-outer diameter of spirally wound tube, do(ii) a 22-inner diameter of spirally wound tube, di(ii) a 23-winding lead of helically wound tube, Pm。
According to the design method of the shell-side boiling tube-side condensed wound tube type heat exchanger, preferably, the arrangement method of the reasonable wound tube can utilize the shell-side space to the maximum extent, and provides a basis for the design calculation method of the liquid phase section and the boiling section (or the liquid phase section, the boiling section and the gas phase section).
The winding pipe arrangement method of the winding pipe type heat exchanger comprises the following steps: winding pipes with the same specification are selected, the winding angles epsilon of the winding pipes in different layers are the same, and the radial layer spacing H isTSame, axial tube spacing H of different layers of wound tubesL,mThe same, the winding diameter of each layer of winding pipe in the winding pipe bundle follows an arithmetic progression; winding diameter DcoLayer gap BTNumber of layers m and core barrel diameter DCThe geometrical constraint relationship of (1) is as follows: dco,m＝DC+2mBT+(2m-1)do，m≤(DB-DC)/2ST(ii) a Radial layer spacing HTAnd radial layer gap BTAxial tube spacing S of the mth layerL,mAnd axial tube clearance BL,mThe mathematical expression of (a) is: sT＝do+BT， SL,m＝(do+BL,m) (ii)/cos (. epsilon.); in each layer of winding pipe, the number of winding pipes is nmAngle of winding epsilon, diameter of winding Dco,mA winding lead PmAnd axial tube spacing SL,mThe geometrical constraint conditions of (1) are as follows:
Figure RE-GDA0003007909520000031
axial effective length E of the winding section and total length L of the winding section of the winding tubecoThe mathematical expression of (a) is: e is N.Pm,
Figure RE-GDA0003007909520000032
Wherein D isBTo a winding diameter, DCIs the diameter of the core barrel, doIs the outside diameter of the tube, BLIs the gap between every two winding pipes of the same layer, STThe distance between the mth layer of winding pipe and the (m + 1) th layer of winding pipe is at least 1.25 times of the pipe diameter according to GB/T151; pmThe lead of the winding pipe of the mth layer is adopted; n ismThe number of winding pipes for the mth layer; doIs the outer diameter of the winding pipe; epsilon is the winding angle of the winding pipe; n is a radical ofmThe number of winding turns of the m-th layer of winding pipe is set; pmThe lead of the winding pipe of the mth layer; dco,mWinding diameter of the m-th layer of winding pipe.
According to the design method of the shell-side boiling tube-side condensed wound tube type heat exchanger, preferably, the calculation methods of the heat exchange coefficients of the shell-side liquid phase section and the gas phase section both adopt a single-phase spiral wound tube type heat exchanger shell-side Gilli formula, and the calculation method of the heat exchange coefficient of the liquid phase section comprises the following steps:
Figure RE-GDA0003007909520000041
wherein ReL,eff＝(uL, effdo)/μL,PrL＝(cLμL)/λL；
In the formula, ReL,eff: the Reynolds number of the shell-side liquid-phase single-phase flow; pr (Pr) ofL: the prandtl number of the shell-side liquid phase;
the method for calculating the heat exchange coefficient of the gas phase section comprises the following steps:
Figure RE-GDA0003007909520000042
wherein ReG,eff＝(uG,effdo)/μG,PrG＝(cGμG)/λG；
In the formula, ReG,eff: the Reynolds number of the shell-side gas-phase single-phase flow; pr (Pr) ofG: prandtl number of shell side gas phase;
application range of spiral wound tube type heat exchanger shell pass single-phase heat exchange formulaEnclose ReL,eff(ReG,eff)＝2000～106， PrL(PrG)＝0.1～10；doIs the outer diameter of the winding pipe; lambda [ alpha ]LIs the heat conductivity coefficient of the shell side liquid phase section of the winding tube type heat exchanger, W (m.K)-1；λGIs the heat conductivity coefficient of the shell side gas phase section of the winding tube type heat exchanger, W (m.K)-1；uL,effIs the effective flow rate of the liquid phase section; u. ofG,effIs the effective flow rate of the gas phase section; mu.sLIs the viscosity of a liquid phase section of a winding tube type heat exchange shell pass, Pa.s-1；μGIs the viscosity of a gas phase section of a winding tube type heat exchange shell pass, Pa.s-1；cLSpecific heat of the liquid phase section of the winding tube type heat exchange shell side, J (kg. K)-1；cGIs the specific heat of the gas phase section of the shell side of the spiral wound tube type heat exchanger, J (kg. K)-1；FiIs a winding angle correction factor; fnArranging correction coefficients for the tube rows;
Figure RE-GDA0003007909520000043
arranging correction factors for the effective tubes of the wound tube bundle; heat transfer coefficient h of shell side boiling sectionTPThe calculation method comprises the following steps:
Figure RE-GDA0003007909520000044
hLOthe heat exchange coefficient when the boiling section is pure liquid phase flow,
Figure RE-GDA0003007909520000045
the method for calculating the Reynolds number of the pure liquid phase flow comprises the following steps:
Figure RE-GDA0003007909520000046
x is Martinelli number, and X is dryness; when the gas phase flows in the boiling section, the heat exchange coefficient is calculated when the gas phase flows as the pure liquid phase, and the Reynolds number of the gas phase flow in the boiling section is calculated by the following method:
Figure RE-GDA0003007909520000051
and calculating gas-liquid phase balance at the corresponding sub-segment temperature according to the mixture phase separation model and the Claberon equation, calculating to obtain the dryness value of each sub-segment, and judging which calculation formula is selected by each sub-segment.
Further, the air conditioner is provided with a fan,
ReLO＜1000，ReVOwhen the Martinelli number is less than 1000, the calculation method of the Martinelli number comprises the following steps:
Figure RE-GDA0003007909520000052
ReLO＜1000，ReVOwhen the Martinelli count is more than 2000, the calculation method of the Martinelli count is as follows:
Figure RE-GDA0003007909520000053
ReLO＞2000，ReVOwhen the Martinelli number is less than 1000, the calculation method of the Martinelli number comprises the following steps:
Figure RE-GDA0003007909520000054
ReLO＞2000，ReVOwhen the Martinelli count is more than 2000, the calculation method of the Martinelli count is as follows:
Figure RE-GDA0003007909520000055
and x is dryness.
In the formula, ρVOShell-side gas phase density; rhoLOShell side liquid phase density; mu.sVOShell-side gas phase dynamic viscosity; mu.sLOShell side liquid phase dynamic viscosity;
and calculating gas-liquid phase balance at the corresponding sub-segment temperature according to the mixture phase separation model and the Claberon equation, calculating to obtain the dryness value of each sub-segment, and judging which calculation formula is selected by each sub-segment.
In accordance with the design of the shell-side boiling tube-side condensing wound tube heat exchanger of the present invention, it is preferred,
phase change exists in the winding pipe, a sectional calculation mode is adopted, and a Boyko's correlation formula is selected for calculating the pipe pass condensation heat exchange coefficient of the winding pipe type heat exchanger:
hTP,tube＝hL,tubeψL,tube
wherein h isL,tubeWhen the flowing liquid is all liquid phase, the tube pass heat exchange coefficient is obtained by calculation. PsiL,tubeThe heat exchange proportionality coefficient of pure liquid phase and two-phase flow;
the Re flowing inside the winding tube is divided into three regions. In the three regions, the relationship of single-phase convection for enhanced heat transfer is as follows:
(1)100≤Re≤Recr
Figure RE-GDA0003007909520000061
(2)Recr＜Re≤22 000
Figure RE-GDA0003007909520000062
(3)20 000＜Re≤150 000
Figure RE-GDA0003007909520000063
ψL,tubethe mathematical expression of the function defined as the tube pass dryness of the winding tube type heat exchanger is as follows:
Figure RE-GDA0003007909520000064
wherein x istubeThe dryness of the winding tube pass is adopted; rhoL,tubeDensity in the liquid phase; rhoV,tubeIs the density of the gas phase.
And (3) determining the calculation method of the heat exchange quantity of the shell pass liquid phase section and the shell pass gas phase section of the wound tube type heat exchanger according to the enthalpy value change and the heat balance of each temperature boundary point (dew point, bubble point and each temperature boundary point of the boiling section) of the shell pass and the gas phase section.
According to the design method of the shell-side boiling tube-side condensed wound tube type heat exchanger, preferably, the boiling section is divided into a plurality of subsections according to the change of temperature and dryness according to the physical property of the shell side, and the mathematical expression of the total heat exchange quantity of the tube-side condensing section is as follows: Δ Htube,TP＝Htube,D-Htube,B＝∑ΔHtube,TP(j)；
The mathematical expression of the sub-section heat exchange quantity of the tube side condensation section is as follows: Δ Htube,TP(j)＝Htube,TP(j+1)-Htube,TP(j)；
The calculation methods of the total heat exchange coefficients of the shell-side liquid phase section, the boiling section and the gas phase section are different; the shell pass liquid phase section and the gas phase section do not have phase change, so the calculation methods of the heat exchange coefficients of the shell pass liquid phase section and the shell pass gas phase section are all Gilli correlation formulas which are respectively equal to the sum. The shell side is in liquid state, and the total heat exchange coefficient of the subsections of the tube side condensation is as follows:
Figure RE-GDA0003007909520000065
the shell side is gaseous, and the total heat exchange coefficient of the subsections of the tube side condensation is as follows:
Figure RE-GDA0003007909520000071
and determining the heat exchange quantity of the liquid phase section and the gas phase section of the shell side according to the enthalpy change of each temperature dividing point (dew point, bubble point, inlet temperature and outlet temperature of the shell side). The mathematical expression of the heat exchange quantity of the shell pass liquid phase section is as follows:
ΔHshell,L＝Hshell,B-Hshell,in＝mcshell,LΔTshell,L＝∑ΔHtube,L(j)＝∑KL(j)AL(j)ΔTln,L(j)
the mathematical expression of the heat exchange quantity of the shell pass gas phase section is as follows:
ΔHshell,G＝Hshell,out-Hshell,D＝mcshell,GΔTshell,G＝∑ΔHtube,G(j)＝∑KG(j)AG(j)ΔlTn,G(j)
the shell pass boiling section has phase change, the boiling section adopts a sectional design calculation method, the boiling section is divided into a plurality of subsections according to the change of temperature and enthalpy, and the mathematical expression of the total heat exchange quantity of the boiling section is as follows:
ΔHshell,TP＝Hshell,D-Hshell,B＝∑ΔHTP,shell(j)
the mathematical expression for each sub-segment in the boiling segment is:
ΔHshell,TP(j)＝Hshell,TP(j+1)-Hshell,TP(j)
according to the law of conservation of energy, the method comprises the following steps:
ΔHshell,TP＝ΔHtube,TP＝∑ΔHTP,shell(j)＝∑ΔHtube,TP(j)
ΔHTP,shell(j)＝ΔHtube,TP(j)＝KTP(j)ATP(j)ΔTln,TP(j)
each sub-segment of the shell side boiling section has a convective heat transfer coefficient (h)TP,shell(j) Calculating the Barbe correlation, convective heat transfer coefficient (h) of the tube pass sub-sectionco,weight,L) And (4) weighting and averaging the heat exchange coefficients of the tube passes. The mathematical expression for the total heat transfer coefficient of each sub-section of the boiling section is:
Figure RE-GDA0003007909520000072
wherein Hshell,BEnthalpy corresponding to the shell-side bubble point temperature, Hshell,DEnthalpy corresponding to shell side dew point temperature, Hshell,inEnthalpy corresponding to the shell side inlet temperature, Hshell,outEnthalpy corresponding to outlet temperature, Δ Hshell,LChange in enthalpy, Δ H, corresponding to the shell-side liquid phase segmentshell,GChange in enthalpy, Δ H, corresponding to the shell-side gas phase sectionshell,TPChange in enthalpy, Δ H, corresponding to the shell boiling stageshell,TP(j) For each sub-segment of the enthalpy change, H, in the shell-side boiling segmentshell,TP(j) Boiling in shell sideEnthalpy values of temperature dividing points of all subsections in the Teng section; htube,BEnthalpy value corresponding to the tube pass bubble point temperature, Htube,DEnthalpy corresponding to shell side dew point temperature, Δ Htube,TPChange in enthalpy, Δ H, corresponding to the shell boiling stagetube,TP(j) For each sub-segment of the enthalpy change, H, in the shell-side boiling segmenttubeTP(j) The enthalpy value of each subsection temperature dividing point in the tube side condensation section is shown.
According to the design method of the shell-side boiling tube-side condensing wound tube type heat exchanger, preferably, the heat exchange amount and the total heat transfer coefficient are known, and then the calculation method of the heat exchange area is as follows:
AL＝ΔHshell,L/(KL·ΔTln,L)
AG＝ΔHshell,G/(KG·ΔTln,G)
ATP,tot＝∑ATP(j)＝ΔHshell,TP(j)/[KTP(j)·ΔTln,TP(j)]
wherein A isLIs the heat exchange area of the liquid phase section; a. theGIs the heat exchange area of the gas phase section; a. theTP,totIs the total heat transfer area of the boiling section; a. theTP(j) Is the heat exchange area of each sub-section in the boiling section.
The invention has the beneficial effects that:
the design method provides an arrangement method of the winding pipe, and can utilize the shell pass space to the maximum extent; secondly, according to the bubble point and the dew point of the working medium, the design method divides the shell side into a liquid phase section and a boiling section (or three parts of the liquid phase section, the boiling section and the gas phase section), and respectively carries out design calculation on the liquid phase section and the boiling section (or three parts of the liquid phase section, the boiling section and the gas phase section); the liquid phase section adopts a single-phase convection heat transfer calculation method to determine the heat exchange area, the heat exchange quantity, the effective length and the like of the liquid phase section; the design method of the boiling section adopts a finite subsection calculation method, the boiling section is divided into a plurality of sections according to the gas-liquid phase equilibrium principle of working medium from a bubble point to a dew point, and the corresponding dryness in each section is calculated respectively; calculating the length of each sub-segment according to the heat balance principle in each segment, and determining the heat exchange area, the heat exchange quantity, the effective length and the like of the boiling segment; the gas phase section adopts a single-phase convection heat transfer calculation method to determine the heat exchange area, the heat exchange quantity, the effective length and the like of the gas phase section; the design method of the winding tube type heat exchanger has the characteristics of high calculation precision, complete design method, high calculation efficiency and the like, and has high commercial value and market popularization value.
Drawings
FIG. 1 is a schematic view of a wound tube heat exchanger (two layers of wound tubes);
FIG. 2 is a view from the direction of FIG. 1A-A;
FIG. 3 is a view from the direction of FIG. 1B-B;
FIG. 4 is a schematic view of a spiral wound tube configuration;
FIG. 5 is a side view of FIG. 4;
FIG. 6 is a schematic diagram showing shell side boiling and tube side condensing wound tube heat exchanger with shell side divided into three parts, namely a liquid phase section, a boiling section and a gas phase section, and a tube side having phase change;
FIG. 7 is a schematic view of a sub-segment calculation region of the boiling segment;
fig. 8 is a flow diagram of a design of a shell-side boiling tube-side condensing wound tube heat exchanger.
In the figure, 1-inner diameter of barrel, DB; 2-core barrel outside diameter, DC; 3-the outer diameter of the spirally wound tube, do; 4-tube spacing, SL, of the same layer of wound tubes; 5-wrap angle, ε; 6-total length of wound section, E; 7-inner layer winding diameter, Dco, 1; 8-outer layer winding diameter, Dco, 2; 9-helical winding pipe layer spacing, ST; 21-the outer diameter of the spirally wound tube, do; 22-inner diameter of the helically wound tube, di; 23-winding lead of the spiral winding tube, Pm; 31-tube pass outlet; 32-a partition between the tube side and the shell side; 33-shell side inlet; 34-shell side liquid phase section; 35-bubble point temperature location point; 36-shell side boiling section; 37-dew point temperature location point; 38-shell side gas phase section; 39-shell side outlet; 40-tube pass inlet; 41-tube pass gas phase section; 42-tube pass liquid phase section.
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.
Embodiment 1, referring to fig. 1 to 8, a method for designing a shell-side boiling tube-side condensing wound tube heat exchanger, in which a wound tube and a tube bundle thereof have a certain geometric constraint relationship according to structural characteristics of the wound tube, and the design method provides a method for arranging the wound tubes of the wound tube heat exchanger based on the geometric constraint relationship, wherein the wound tubes of the same specification are selected, the wound tubes of different layers have the same winding angle epsilon, and the radial layer spacing H is the sameTSame, different layer winding pipe axial pipe spacing HL,mThe same, the winding diameter of each layer of winding pipe in the winding pipe bundle follows an arithmetic progression; winding diameter Dco,mLayer gap BTThe number of layers m and the outer diameter D of the core tubeCThe geometric constraint relation of (A) is shown as formula (1); radial layer spacing HTAnd radial layer gap BTAxial tube spacing S of the mth layerL,mAnd axial tube clearance BL,mThe mathematical expression of (a) is shown as formula (2); in each layer of winding pipe, the number of winding pipes is nmWinding angle epsilon and winding diameter D of winding pipe of mth layerco,mWinding lead PmAnd axial tube spacing SL,mThe geometric constraint condition of (2) is shown as formula (3); axial effective heat exchange length E of winding section and total length L of winding section of m-th layer of winding pipeco,mThe mathematical expression of (a) is shown as formula (4); wherein D isBIs the inner diameter of the cylinder DCIs the outer diameter of the core barrel, doIs the outside diameter of the tube, BLIs the gap between every two winding pipes of the same layer, STThe distance between the mth layer of winding pipe and the (m + 1) th layer of winding pipe is at least 1.25 times of the pipe diameter according to GB/T151; pmThe lead of the winding pipe of the mth layer is adopted; n ismThe number of winding pipes for the mth layer; doIs the outer diameter of the winding pipe; epsilon is the winding angle of the winding pipe; n is a radical ofmThe number of winding turns of the m-th layer of winding pipe is set; pmA lead for the mth layer of wound tubing; dco,mWinding diameter of the m-th layer of winding pipe.
Dco,m＝DC+2mBT+(2m-1)do，m≤(DB-DC)/2ST (1)
ST＝do+BT，SL,m＝(do+BL,m)/cos(ε) (2)
Figure RE-RE-GDA0003007909520000101
Figure RE-RE-GDA0003007909520000102
In the design method of the wound tube type heat exchanger for shell side boiling tube side condensation, the dew point temperature and the bubble point temperature of a shell side working medium are calculated according to a mixture phase separation model, a Clarbelon equation and the like, the shell side is divided into two three parts according to the bubble point temperature, the dew point temperature, the outlet dryness, the outlet temperature and the like, and if the dryness of an outlet section is less than 1, the whole wound tube type heat exchanger is divided into two parts, namely a liquid phase section and a boiling section; if the dryness of the outlet is equal to 1, the whole wound tube type heat exchanger is divided into a liquid phase section, a boiling section and a gas phase section; the bubble point temperature from the shell side inlet to the fluid working medium is a liquid phase section, the bubble point temperature from the fluid working medium to the dew point temperature is a boiling section, and the bubble point temperature from the dew point temperature to the shell side outlet is a gas phase section; the shell pass Gilli formula of the single-phase spiral wound tube type heat exchanger is adopted as the calculation method of the heat exchange coefficients of the shell pass liquid phase section and the gas phase section, the calculation method of the heat exchange coefficient of the liquid phase section is shown as the formula (5), and the calculation method of the heat exchange coefficient of the gas phase section is shown as the formula (7); the application range of the shell pass single-phase heat exchange formula of the spiral wound tube type heat exchanger is ReL,eff(ReG,eff)＝2000～106，PrL(PrG)＝0.1～10；doIs the outer diameter of the winding pipe; lambda [ alpha ]LIs the heat conductivity coefficient of the shell side liquid phase section of the winding tube type heat exchanger, W (m.K)-1；λGIs the heat conductivity coefficient of the shell side gas phase section of the winding tube type heat exchanger, W (m.K)-1； uL,effIs the effective flow rate of the liquid phase section; u. ofG,effIs the effective flow rate of the gas phase section; mu.sLFor winding the tubular heat exchange shellViscosity of the liquid phase of the process, Pa.s-1；μGIs the viscosity of a gas phase section of a winding tube type heat exchange shell pass, Pa.s-1；cLIs the specific heat of the liquid phase section of the winding tube type heat exchange shell side, J (kg. K)-1；cGIs the specific heat of the gas phase section of the shell side of the spiral wound tube type heat exchanger, J (kg. K)-1；FiThe winding angle correction coefficient; fnArranging correction coefficients for the tube rows;
Figure RE-GDA0003007909520000111
the correction factor is arranged for the effective tubes of the wound tube bundle.
Figure RE-GDA0003007909520000112
ReL,eff＝(uL,effdo)/μL,Pr＝(cLμL)/λL (6)
Figure RE-GDA0003007909520000113
ReG,eff＝(uG,effdo)/μG,Pr＝(cGμG)/λG (8)
A design method of a wound tube type heat exchanger with shell side boiling tube side condensation is characterized in that a core design calculation method is a calculation method of a heat exchange coefficient, a heat exchange area, a heat exchange amount, a pressure drop and the like of a shell side boiling section. Wherein h is the heat exchange coefficient of the shell side boiling sectionTPThe calculation method is shown as formula (9).
Figure RE-GDA0003007909520000114
In a design method of a wound tube type heat exchanger with shell side boiling tube side condensation, hLThe calculation method is the same as the formula (5) for the heat exchange coefficient when the boiling section is pure liquid phase flow; however, the Reynolds number is calculated differently,the calculation method of the Reynolds number of the pure liquid phase flow is shown as the formula (11).
Figure RE-GDA0003007909520000115
Figure RE-GDA0003007909520000116
In a design method of a winding tube type heat exchanger with shell side boiling tube side condensation, X is Martinelli number. Firstly, calculating the Reynolds numbers of a gas phase and a liquid phase in a mixed phase, wherein the Reynolds number of the liquid phase flowing in a boiling section is calculated by the method shown in an equation (11); the calculation method of the Reynolds number of the gas phase flow in the boiling section is shown as the formula (10); second, the Reynolds number Re according to the flow of the liquid phaseLOReynolds number Re of gas flowVOThe range of (1), the Martinelli number calculation method has a corresponding formula, ReLO＜1000，ReVOWhen the Martinelli count is less than 1000, the calculation method of the Martinelli count is shown as a formula (12); reLO＜1000，ReVOWhen the Martinelli count is more than 2000, the calculation method of the Martinelli count is shown as a formula (13); reLO＞2000， ReVOWhen the Martinelli number is less than 1000, the calculation method of the Martinelli number is shown as a formula (14); reLO＞2000，ReVOWhen the Martinelli count is more than 2000, the calculation method of the Martinelli count is shown as a formula (15); in the formulas (12) to (15), x is the dryness, the gas-liquid phase balance at the corresponding sub-segment temperature is calculated according to the mixture phase separation model and the Clarbelon equation, the dryness value of each sub-segment is obtained through calculation, and which calculation formula is selected by each sub-segment is judged.
Figure RE-GDA0003007909520000117
Figure RE-GDA0003007909520000118
Figure RE-GDA0003007909520000121
Figure RE-GDA0003007909520000122
In a design method of a winding tube type heat exchanger with shell side boiling tube side condensation, a fluid working medium of a tube side is high-temperature high-pressure liquid, and the tube side has phase change; critical Reynolds number, Re, defining the boundary between laminar and turbulent flow in the winding tubecrIs calculated as shown in formula (16), δ ═ di/Dco，diTo wind the inner diameter of the tube, DcoIs the winding diameter of the winding tube. The calculation of the Reynolds number of the tube side is shown in equation (17).
Recr＝2300(1+8.6δ0.45) (16)
Figure RE-GDA0003007909520000123
In a design method of a winding tube type heat exchanger with shell side boiling tube side condensation, the flow state of a tube side is divided into three calculation intervals according to a critical Reynolds number, and each interval is provided with a corresponding calculation formula; when Re is more than or equal to 100co≤RecrMeanwhile, the calculation method of the tube pass heat exchange coefficient is shown as the formula (18); when Recr＜RecoWhen the heat exchange coefficient of the tube pass is less than or equal to 22000, the calculation method of the heat exchange coefficient of the tube pass is shown as the formula (19); when Re is more than 20000 and less than or equal to 150000, the calculation method of the tube pass heat exchange coefficient is shown as the formula (20).
Figure RE-GDA0003007909520000124
Figure RE-GDA0003007909520000125
Figure RE-GDA0003007909520000126
In a design method of a shell side boiling tube side condensation wound tube type heat exchanger, the calculation methods of the total heat exchange coefficients of a liquid phase section, a boiling section and a gas phase section are different; the heat exchange coefficients of the winding pipes of the winding pipe type heat exchanger from the inner layer to the outer layer are different, and the number of the winding pipes on different layers is also different; phase change exists in the winding pipe, and a Boyko's correlation formula is selected for calculating the pipe pass condensation heat exchange coefficient of the winding pipe type heat exchanger:
hTP,tube＝hL,tubeψL,tube (21)
wherein h isL,tubeWhen the flowing liquid is all liquid phase, the tube pass heat exchange coefficient is obtained by calculation. PsiL,tubeThe heat exchange proportionality coefficient of pure liquid phase and two-phase flow;
the Re flowing inside the winding tube is divided into three regions. The three regions are expressed by single-phase convection correlations (22) to (24) for enhancing heat transfer:
(1)100≤Re≤Recr
Figure RE-GDA0003007909520000127
Figure RE-GDA0003007909520000128
(2)Recr＜Re≤22 000
Figure RE-GDA0003007909520000131
(3)20 000＜Re≤150 000
Figure RE-GDA0003007909520000132
Figure RE-GDA0003007909520000135
ψL,tubethe mathematical expression of the function defined as the tube pass dryness of the winding tube type heat exchanger is shown as the formula (25):
Figure RE-GDA0003007909520000133
wherein x istubeThe dryness of the winding tube pass is adopted; rhoL,tubeDensity in the liquid phase; rhoV,tubeIs the density of the gas phase.
In a design method of a wound tube type heat exchanger with shell pass boiling tube pass condensation, a boiling section is divided into a plurality of subsections according to the change of temperature and dryness according to the physical property of a shell pass, and the mathematical expression of the total heat exchange quantity of a tube pass condensation section is shown as a formula (26); the mathematical expression of the sub-section heat exchange quantity of the tube side condensation section is shown as the formula (27):
ΔHtube,TP＝Htube,D-Htube,B＝∑ΔHtube,TP(j) (26)
ΔHtube,TP(j)＝Htube,TP(j+1)-Htube,TP(j) (27)
in a design method of a shell side boiling tube side condensation wound tube type heat exchanger, the calculation methods of the total heat exchange coefficients of a shell side liquid phase section, a boiling section and a gas phase section are different; the shell pass liquid phase section and the gas phase section do not have phase change, so the calculation methods of the heat exchange coefficients of the shell pass liquid phase section and the shell pass gas phase section are all Gilli correlation formulas which are h respectivelyshell,LAnd hshell,G. The total heat exchange coefficient of the shell side liquid state and the sub-section of the tube side condensation is shown as the formula (28); the total heat transfer coefficient of the shell side gas state and the sub-section of the tube side condensation is shown as the formula (29). And determining the heat exchange quantity of the liquid phase section and the gas phase section of the shell side according to the enthalpy change of each temperature dividing point (dew point, bubble point, inlet temperature and outlet temperature of the shell side). The mathematical expression of the heat exchange quantity of the shell pass liquid phase section is shown as a formula (30); the mathematical expression of the heat exchange quantity of the shell-side gas phase section is shown as the formula (31). The shell side boiling section has phase change, the boiling section adopts a sectional design calculation method, the boiling section is divided into a plurality of subsections according to the change of temperature and enthalpy value, and the mathematical expression of the total heat exchange quantity of the boiling section is shown as a formula (32); the mathematical expression for each sub-segment in a Teng segment is shown as equation (33). Equations (34) to (35) can be obtained from the law of conservation of energy. Each sub-segment of the shell side boiling section has a convective heat transfer coefficient (h)TP,shell(j) Calculating the Barbe correlation, convective heat transfer coefficient (h) of the tube pass sub-segmentsco,weight,L) And (4) weighting and averaging the heat exchange coefficients of the tube passes. The mathematical expression of the total heat transfer coefficient of each sub-segment of the boiling segment is shown as equation (36):
Figure RE-GDA0003007909520000134
Figure RE-GDA0003007909520000141
ΔHshell,L＝Hshell,B-Hshell,in＝mcshell,LΔTshell,L＝∑ΔHtube,L(j)＝∑KL(j)AL(j)ΔTln,L(j) (30)
ΔHshell,G＝Hshell,out-HshellD＝mcshell,GΔTshell,G＝∑ΔHtube,G(j)＝∑KG(j)AG(j)ΔTln,G(j) (31)
ΔHshell,TP＝Hshell,D-Hshell,B＝∑ΔHTP,shell(j) (32)
ΔHshell,TP(j)＝Hshell,TP(j+1)-Hshell,TP(j) (33)
ΔHshell,TP＝ΔHtube,TP＝∑ΔHTP,shell(j)＝∑ΔHtube,TP(j) (34)
ΔHTP,shell(j)＝ΔHtube,TP(j)＝KTP(j)ATP(j)ΔTln,TP(j) (35)
Figure RE-GDA0003007909520000142
in the above formulas (28) to (36), Hshell,BEnthalpy corresponding to the shell-side bubble point temperature, Hshell,DEnthalpy corresponding to the shell side dew point temperature, Hshell,inEnthalpy corresponding to the shell side inlet temperature, Hshell,outEnthalpy corresponding to outlet temperature, Δ Hshell,LChange in enthalpy, Δ H, corresponding to the shell-side liquid phase segmentshell,GChange in enthalpy, Δ H, corresponding to the shell-side gas phase sectionshell,TPChange in enthalpy, Δ H, corresponding to the shell-side boiling segmentshell,TP(j) For each sub-segment of the enthalpy change, H, in the shell-side boiling segmentshell,TP(j) The enthalpy value of each subsection temperature demarcation point in the shell side boiling section; htube,BEnthalpy value corresponding to the tube pass bubble point temperature, Htube,DEnthalpy corresponding to shell side dew point temperature, Δ Htube,TPChange in enthalpy, Δ H, corresponding to the shell boiling stagetube,TP(j) For each sub-segment of the enthalpy change, H, in the shell-side boiling segmenttube,TP(j) The enthalpy value of each subsection temperature dividing point in the tube side condensation section is shown.
In a design method of a winding tube type heat exchanger with shell side boiling tube side condensation, a calculation method of heat exchange areas of a liquid phase section, a boiling section and a gas phase section is as shown in the formula-I; a. theLIs the heat exchange area of the liquid phase section; a. theGIs the heat exchange area of the gas phase section; a. theTP,totIs the total heat exchange area of the boiling section; a. theTP(j) Is the heat exchange area of each sub-section in the boiling section.
AL＝ΔHshell,L/(KL·ΔTln,L) (37)
AG＝ΔHshell,G/(KG·ΔTln,G) (38)
ATP,tot＝∑ATP(j)＝ΔHshell,TP(j)/[KTP(j)·ΔTln,TP(j)] (39)
In a design method of a wound tube heat exchanger with shell side boiling tube side condensation, the flow of shell side fluid is divided into a liquid phase section, a boiling section and a gas phase section, and the calculation formula of single-phase flow pressure drop of the liquid phase section and the gas phase section is shown as the formula and; wherein, the application range is as follows: re is 2000 to 106,Pr＝0.1～10；UL,eff(UG,eff) Is the shell pass effective flow rate; gL,eff(GG,eff) Effective mass flow rate; ci: a winding angle correction factor; cn: pipe row arrangement repairA positive coefficient;
Figure RE-GDA0003007909520000151
arranging correction coefficients for the effective pipes; n is a radical ofaThe number of tube rows in the flow direction; n is the number of winding pipes in the flow direction; n is a radical ofnThe number of tube windings for winding the tube).
Figure RE-GDA0003007909520000152
Figure RE-GDA0003007909520000153
Figure RE-GDA0003007909520000154
In the design method of the shell side boiling tube side condensation wound tube type heat exchanger, the mathematical expression of the total pressure drop of two-phase flow (liquid phase and gas phase exist simultaneously) is shown as the formula; pressure head delta P of water purificationsThe calculation of (A) is shown in the formula; dynamic head delta PmThe calculation of (A) is shown as the formula; wherein θ is an inclination angle; x is dryness; rhoVOIs the gas phase density; rhoLOIs a liquid phase density; gtIs the total area mass flow of the fluid; u. ofLOThe velocity in the liquid phase; u. ofVOIs the gas phase velocity.
ΔPtp＝ΔPtp,s+ΔPtp,m+ΔPtp,f (43)
ΔPtp,s＝ρtpgΔL(sinθ) (44)
ΔPtp,m＝Gt{[(1-x)uLO+xuVO]out-[(1-x)uLO+xuVO]in} (45)
ρtp＝xρVO+(1-x)ρLO，uLO＝(1-x)Gt/ρLO，uVO＝xGt/ρLO (46)
Shell side boiling pipeIn the design method of the winding tube type heat exchanger of process condensation, the friction pressure drop delta PfThe calculation method of (A) is shown in formula (II); wherein w is an index in the resistance coefficient calculation formula, and is taken as 0.25. B is an empirical coefficient, the value of which is equal to the area mass flow GtAnd the coefficient Y.
Figure RE-GDA0003007909520000158
Figure RE-GDA0003007909520000155
Figure RE-GDA0003007909520000156
Figure RE-GDA0003007909520000157
In a design method of a wound tube type heat exchanger with shell side boiling tube side condensation, total shell side pressure drop delta Pshell,totThe calculation method of (2) is shown as the formula.
ΔPshell,tot＝ΔPL+ΔPG+ΔPTP (51)
In a design method of a wound tube type heat exchanger with shell side boiling tube side condensation, phase change of tube side fluid exists, Fuchs correlation is selected for calculation of gas-liquid two-phase flow resistance in a wound tube, and a mathematical expression of the Fuchs correlation is shown as a formula (52):
Figure RE-GDA0003007909520000161
wherein dptp,tubeIs a gas-liquid two-phase flow pressure drop; dpL,tubePressure drop in the pure liquid phase; dpV,tubePressure drop in the pure vapor phase;
Figure RE-GDA0003007909520000162
calculating the coefficient for the resistance of the gas-liquid two-phase flow in the winding pipe;
Figure RE-GDA0003007909520000163
dpL,tubeand dpV,tubeIs represented by the following formulas (53) to (55):
Figure RE-GDA0003007909520000164
Figure RE-GDA0003007909520000165
Figure RE-GDA0003007909520000166
in formulae 53) to 55, FrL,tubeFroud number of liquid phase in tube pass; rhoL,tubeThe density of the tube pass working medium liquid phase; rhoV,tubeThe density of tube pass working medium gas phase; x is the number oftubeThe dryness of the tube pass working medium; a isi，b，ciThe coefficients were calculated for the tube side resistance of the wound tube heat exchanger and are shown in table 1.
TABLE 1 calculation of tube pass resistance coefficient of wound tube heat exchanger
Figure RE-GDA0003007909520000167
FrL,tubeA dimensionless parameter, which is a Froud number, that characterizes the relative magnitudes of the inertial force and the gravitational force of a fluid, and whose mathematical expression is shown in equation (56):
Figure RE-GDA0003007909520000168
where ρ isL,tubeThe density of the tube pass working medium liquid phase; g is the acceleration of gravity; m isL,tubeIs prepared from liquidThe mass flow of the phases; m isL,tubeMass flow of tube pass working medium liquid phase, mL,tube＝mtube(1-xtube)；diIs the inner diameter of the tube pass of the winding tube type heat exchanger.
Iterative calculation is required, and the design method of the wound tube heat exchanger with shell pass boiling and tube pass condensation is programmed by means of a programming tool to realize the iterative calculation.
A design method of a wound tube heat exchanger with shell pass boiling and tube pass condensation mainly comprises the design calculation of heat exchange coefficients, heat exchange amount, heat exchange area and pressure drop of a liquid phase section, a boiling section and a gas phase section of the wound tube heat exchanger with shell pass boiling and tube pass condensation; programming the design method of the wound tube type heat exchanger with shell side boiling and tube side condensation by means of a programming tool to realize the design calculation of the wound tube type heat exchanger with shell side boiling and tube side condensation.
A design flow chart of a design method of a shell-side boiling and tube-side condensing wound tube heat exchanger related to the invention is shown in fig. 8; starting design calculation, firstly, inputting physical parameters of the working medium, including specific heat, thermal conductivity, density, dew point temperature, bubble point temperature and the like of the working medium; secondly, inputting the designed rated working condition, comprising: the heat load Qload, shell-side allowable pressure drop delta Pload, tube, heat exchange allowance, area allowance and the like; thirdly, according to the design requirement, according to the geometric constraint relationship of the formulas (1) to (4), giving a preliminary structure, which comprises: 1-barrel inside diameter, DB; 2-core barrel outside diameter, DC; 3-the outer diameter of the spirally wound tube, do; 4-tube spacing, SL, of the same layer of wound tubes; 5-wrap angle, ε; 6-total length of wound section, E; 7-inner layer winding diameter, Dco, 1; 8-outer layer winding diameter, Dco, 2; 9-helical winding pipe layer spacing, ST; 21-the outer diameter of the spirally wound tube, do; 22-inner diameter of the helically wound tube, di; 23-winding lead of the spiral winding tube, Pm; fourthly, dividing the shell side into a liquid phase section, a boiling section and a gas phase section according to the dew point temperature and the bubble point temperature of the working medium, and respectively calculating heat exchange coefficients (hL, hTP (j) and hG) corresponding to the three sections; fifthly, calculating the heat exchange coefficient of the tube pass in sections; sixthly, calculating the heat exchange area, the heat exchange quantity and the bubble point temperature position of the liquid phase section according to the heat balance; seventhly, calculating the heat exchange area, the heat exchange quantity and the dew point temperature position of the boiling section according to the heat balance; eighthly, calculating the heat exchange area and the heat exchange quantity of the gas phase section according to the heat balance; adding the heat exchange quantities of the liquid phase section, the gas phase section and the boiling section, and calculating the total heat exchange area Atot, the total heat exchange quantity Qdesign, the total length E of the winding section, the bubble point temperature position and the dew point temperature position; tenthly, judging whether Qdesign is greater than or equal to Qload or not according to design calculation, if the relational expression is not established, rearranging the structure, and if the relational expression is established, carrying out the next step; eleventh, calculating the tube side pressure drop and the shell side pressure drop of the wound tube heat exchanger comprises: tube side pressure drop, shell side total pressure drop delta Pdesign, shell, tot, shell side liquid phase section pressure drop delta Pdesign, L, shell side boiling phase section pressure drop delta Pdesign, TP, shell side gas phase section pressure drop delta Pdesign, G; twelfth, whether the conditions of delta Pload, shell, tot which is more than or equal to delta Pdesign, shell, tot and delta Pload, tube which are more than or equal to two conditions are simultaneously satisfied is judged according to design calculation, if the relation is not satisfied, the structure is rearranged, and if the relation is satisfied, the result is output.
The following table shows an example of the refrigerant R-134a heated to boiling by hot water in the winding pipe, wherein R-134a flows in the shell side, hot water flows in the pipe, the design conditions and physical properties are shown in table 2, and the calculation results by the design method and formula of the present invention are shown in table 3.
TABLE 2 physical properties and working medium design conditions in the coiled heat exchanger
Figure RE-GDA0003007909520000181
TABLE 3 calculation of wound tube Heat exchangers
Figure RE-GDA0003007909520000182
According to the design method of the shell side boiling tube side condensed wound tube type heat exchanger, a boiling section is divided into a plurality of sections according to the gas-liquid phase balance principle of a working medium from a bubble point to a dew point, and corresponding dryness in each section is calculated respectively; calculating the length of each sub-segment according to the heat balance principle in each segment, and determining the heat exchange area, the heat exchange amount, the effective length and the like of the boiling segment; the gas phase section adopts a single-phase convection heat transfer calculation method to determine the heat exchange area, the heat exchange quantity, the effective length and the like of the gas phase section; the design method of the winding tube type heat exchanger has the characteristics of high calculation precision, complete design method, high calculation efficiency and the like, and has high commercial value and market popularization value.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (9)

1. A design method of a wound tube heat exchanger with shell side boiling tube side condensation is characterized in that according to the bubble point and the dew point of a working medium, the shell side is divided into a liquid phase section and a boiling section, or the shell side is divided into a liquid phase section, a boiling section and a gas phase section, and corresponding sections are respectively designed and calculated to determine the heat exchange coefficient, the pressure drop, the heat exchange quantity, the heat exchange area and the axial effective heat exchange length of the winding section of each section; if the dryness of the outlet of the wound tube type heat exchanger is less than 1, the whole wound tube type heat exchanger is divided into two parts, namely a liquid phase section and a boiling section; if the dryness of the outlet of the winding pipe type heat exchanger is equal to 1, the whole winding pipe type heat exchanger is divided into a liquid phase section, a boiling section and a gas phase section; phase change exists in the tube side condensation section, and design calculation is carried out on the tube side condensation section in a sectional mode.
2. The design method of a shell side boiling tube side condensed wound tube heat exchanger as claimed in claim 1, comprising the steps of:
s1: inputting physical parameters of a working medium;
s2: inputting a designed rated working condition;
s3: according to design requirements, setting structural parameters;
s4: dividing a shell pass into a liquid phase section, a condensation section and a gas phase section according to the dew point temperature and the bubble point temperature of a working medium, and respectively calculating heat exchange coefficients hL, hTP (j) and hG corresponding to the three sections;
s5: calculating the heat exchange coefficient of the tube pass in a segmented manner;
s6: calculating the heat exchange area, the heat exchange quantity and the bubble point temperature position of the liquid phase section according to the heat balance;
s7: calculating the heat exchange area, the heat exchange quantity and the dew point temperature position of the boiling section according to the heat balance;
s8: calculating the heat exchange area and the heat exchange quantity of the gas phase section according to the heat balance;
s9: adding the heat exchange quantity and the heat exchange area of the liquid phase section, the gas phase section and the boiling section, and calculating the total heat exchange area Atot, the total heat exchange quantity Qdesign, the total length E of the winding section, the bubble point temperature position and the dew point temperature position;
s10: judging whether Qdesign is more than or equal to Qload or not according to design calculation, if the relational expression is not established, rearranging the structure, and if the relational expression is established, carrying out the next step;
s11: calculating the tube side pressure drop and the shell side pressure drop of the wound tube type heat exchanger, comprising the following steps of: tube side pressure drop | delta P | design, tube, shell total pressure drop | delta P | design, shell, tot, shell liquid phase section pressure drop | delta P | design, L, shell boiling phase section pressure drop | delta P | design, TP, shell gas phase section pressure drop | delta P | design, G;
s12: and judging whether the two conditions of | delta P | load, shell, tot ≧ Δ P | design, shell, tot and | delta P | load, tube ≧ Δ P | design and tube are simultaneously satisfied according to design calculation, if the relation is not satisfied, rearranging the structure, and if the relation is satisfied, outputting the result.
3. The design method of the shell side boiling tube side condensed wound tube type heat exchanger as claimed in claim 2, wherein the physical parameters of the working medium comprise specific heat, thermal conductivity, density, dew point temperature and bubble point temperature of the working medium; the designed rated working conditions comprise: the method comprises the following steps of carrying out heat load Qload, shell side allowable pressure drop | delta P | load, shell side and tube side allowable pressure drop | delta P | load, tube, heat exchange allowance and area allowance; the structural parameters comprise: 1-barrel inside diameter, DB; 2-core barrel outside diameter, DC; 3-the outer diameter of the spirally wound tube, do; 4-tube spacing, SL, of the same layer of wound tubes; 5-wrap angle, ε; 6-total length of wound section, E; 7-inner layer winding diameter, Dco, 1; 8-outer layer winding diameter, Dco, 2; 9-helical winding pipe layer spacing, ST; 21-the outer diameter of the spirally wound tube, do; 22-inner diameter of the helically wound tube, di; 23-winding lead of spiral winding tube, Pm.
4. The design method of the shell side boiling tube side condensed wound tube heat exchanger as claimed in claim 2, wherein the design method comprises a method for arranging wound tubes, and the method for arranging wound tubes of the wound tube heat exchanger is as follows: winding pipes with the same specification are selected, the winding angles epsilon of the winding pipes in different layers are the same, and the radial layer spacing H isTSame, axial tube spacing H of different layers of wound tubesL,mThe same, the winding diameter of each layer of winding pipe in the winding pipe bundle follows an arithmetic progression; winding diameter DcoLayer gap BTNumber of layers m and core barrel diameter DCThe geometrical constraint relationship of (1) is as follows: dco,m＝DC+2mBT+(2m-1)do，m≤(DB-DC)/2ST(ii) a Radial layer spacing HTAnd radial layer gap BTAxial tube spacing S of the mth layerL,mAnd axial tube clearance BL,mThe mathematical expression of (a) is: sT＝do+BT，SL,m＝(do+BL,m) (ii)/cos (. epsilon.); in each layer of winding pipe, the number of winding pipes is nmAngle of winding epsilon, diameter of winding Dco,mWinding lead PmAnd axial tube spacing SL,mThe geometrical constraint conditions of (1) are as follows:
Figure FDA0002905380050000021
axial effective length E of the winding section and total length L of the winding section of the winding tubecoThe mathematical expression of (a) is: e is N.Pm,
Figure FDA0002905380050000031
Wherein D isBTo a winding diameter, DCIs the diameter of the core barrel, doIs the outside diameter of the tube, BLIs the gap between every two winding pipes of the same layer, STThe distance between the mth layer of winding pipe and the (m + 1) th layer of winding pipe is at least 1.25 times of the pipe diameter according to GB/T151; pmThe lead of the winding pipe of the mth layer is adopted; n ismThe number of winding pipes for the mth layer; doIs the outer diameter of the winding pipe; epsilon is the winding angle of the winding pipe; n is a radical ofmThe number of winding turns of the m-th layer of winding pipe is set; pmThe lead of the winding pipe of the mth layer; dco,mWinding diameter of the m-th layer of winding pipe.
5. The design method of the shell side boiling tube side condensed wound tube type heat exchanger as claimed in claim 2, wherein the calculation methods of the heat exchange coefficients of the shell side liquid phase section and the gas phase section both adopt the gili formula of the shell side of the single-phase spiral wound tube type heat exchanger, and the calculation method of the heat exchange coefficient of the liquid phase section is as follows:
Figure FDA0002905380050000032
wherein ReL,eff＝(uL,effdo)/μL,PrL＝(cLμL)/λL(ii) a Wherein, ReL,eff: the Reynolds number of the shell-side liquid-phase single-phase flow; pr (Pr) ofL: the method for calculating the prandtl number of the shell pass liquid phase and the heat exchange coefficient of the gas phase section comprises the following steps:
Figure FDA0002905380050000033
wherein ReG,eff＝(uG,effdo)/μG,PrG＝(cGμG)/λG(ii) a Wherein, ReG,eff: the Reynolds number of the shell-side gas-phase single-phase flow; pr (Pr) ofG: the application range of the shell-side single-phase heat exchange formula of the shell-side gas phase and the spiral wound tube type heat exchanger is ReL,eff(ReG,eff)＝2000～106，PrL(PrG)＝0.1～10；doIs the outer diameter of the winding pipe; lambda [ alpha ]LIs the heat conductivity coefficient of the shell side liquid phase section of the winding tube type heat exchanger, W (m.K)-1；λGIs the heat conductivity coefficient of the shell side gas phase section of the winding tube type heat exchanger, W (m.K)-1；uL,effIs the effective flow rate of the liquid phase section; u. ofG,effIs the effective flow rate of the gas phase section; mu.sLIs the viscosity of a liquid phase section of a winding tube type heat exchange shell pass, Pa.s-1；μGIs the viscosity of a gas phase section of a winding tube type heat exchange shell pass, Pa.s-1；cLSpecific heat of the liquid phase section of the winding tube type heat exchange shell side, J (kg. K)-1；cGIs the specific heat of the gas phase section of the shell side of the spiral wound tube type heat exchanger, J (kg. K)-1；FiIs a winding angle correction factor; fnArranging correction coefficients for the tube rows;
Figure FDA0002905380050000034
arranging correction factors for the effective tubes of the wound tube bundle; heat transfer coefficient h of shell side boiling sectionTPThe calculation method comprises the following steps:
Figure FDA0002905380050000035
hLthe heat exchange coefficient when the boiling section is pure liquid phase flow,
Figure FDA0002905380050000036
the method for calculating the Reynolds number of the pure liquid phase flow comprises the following steps:
Figure FDA0002905380050000041
x is Martinelli number, and X is dryness; when the gas phase flows in the boiling zone, hLOThe Reynolds number of the gas phase flow in the boiling section is calculated by the following method in the same time of pure liquid phase flow:
Figure FDA0002905380050000042
6. the design method of the shell side boiling tube side condensed wound tube type heat exchanger as claimed in claim 2, wherein the Martinelli number calculation method is adopted during boiling
ReLO＜1000，ReVOWhen the Martinelli number is less than 1000, the calculation method of the Martinelli number comprises the following steps:
Figure FDA0002905380050000043
ReLO＜1000，ReVOwhen the Martinelli count is more than 2000, the calculation method of the Martinelli count is as follows:
Figure FDA0002905380050000044
ReLO＞2000，ReVOwhen the Martinelli number is less than 1000, the calculation method of the Martinelli number comprises the following steps:
Figure FDA0002905380050000045
ReLO＞2000，ReVOwhen the Martinelli count is more than 2000, the calculation method of the Martinelli count is as follows:
Figure FDA0002905380050000046
in the formula, ρVOShell-side gas phase density; rhoLOShell side liquid phase density; mu.sVOShell-side gas phase dynamic viscosity; mu.sLOShell side liquid phase dynamic viscosity; and x is dryness.
7. The design method of the shell side boiling tube side condensed wound tube type heat exchanger according to claim 2, characterized in that phase change exists in the wound tube, a sectional calculation mode is adopted, and the calculation of the tube side condensation heat exchange coefficient of the wound tube type heat exchanger adopts a Boyko's correlation formula: h isTP,tube＝hL,tubeψL,tubeWherein h isL,tubeIs in a flowing liquid phaseThen, the tube pass heat exchange coefficient psi obtained by calculationL,tubeThe heat exchange proportionality coefficient of pure liquid phase and two-phase flow;
the flow inside the winding pipe is divided into three areas, and the single-phase convection correlation for enhancing heat transfer in the three areas is as follows:
(1)100≤Re≤Recr
Figure FDA0002905380050000051
(2)Recr＜Re≤22 000
Figure FDA0002905380050000052
(3)20 000＜Re≤150 000
Figure FDA0002905380050000053
ψL,tubethe mathematical expression of the function defined as the tube pass dryness of the winding tube type heat exchanger is as follows:
Figure FDA0002905380050000054
wherein x istubeThe dryness of the winding tube pass is adopted; rhoL,tubeDensity in the liquid phase; rhoV,tubeIs the density of the gas phase.
8. The design method of the shell side boiling tube side condensed wound tube type heat exchanger as claimed in claim 2, wherein the boiling section is divided into a plurality of sub-sections according to the change of temperature and dryness according to the physical property of the shell side, and the mathematical expression of the total heat exchange quantity of the tube side condensation section is as follows: Δ Htube,TP＝Htube,D-Htube,B＝∑ΔHtube,TP(j)；
The mathematical expression of the sub-section heat exchange quantity of the tube side condensation section is as follows: Δ Htube,TP(j)＝Htube,TP(j+1)-Htube,TP(j)；
The calculation methods of the total heat exchange coefficients of the shell-side liquid phase section, the boiling section and the gas phase section are different; the shell pass liquid phase section and the gas phase section do not have phase change, so the calculation methods of the heat exchange coefficients of the shell pass liquid phase section and the shell pass gas phase section are all Gilli correlation formulas, and h is respectivelyshell,LIs a sum of hshell,G(ii) a The shell side is in liquid state, and the total heat exchange coefficient of the subsections of the tube side condensation is as follows:
Figure FDA0002905380050000055
the shell side is gaseous, and the total heat exchange coefficient of the subsections of the tube side condensation is as follows:
Figure FDA0002905380050000056
determining the heat exchange quantity of the shell pass liquid phase section and the gas phase section according to the enthalpy change of each temperature demarcation point (dew point, bubble point, inlet temperature and outlet temperature of the shell pass), wherein the mathematical expression of the heat exchange quantity of the shell pass liquid phase section is as follows:
ΔHshell,L＝Hshell,B-Hshell,in＝mcshell,LΔTshell,L＝∑ΔHtube,L(j)＝∑KL(j)AL(j)ΔTln,L(j)
the mathematical expression of the heat exchange quantity of the shell pass gas phase section is as follows:
Figure FDA0002905380050000062
the shell side boiling section has phase change, the boiling section adopts a sectional design calculation method to divide the boiling section into a plurality of subsections according to the change of temperature and enthalpy, and the mathematical expression of the total heat exchange quantity of the boiling section is as follows:
ΔHshell,TP＝Hshell,D-Hshell,B＝∑ΔHTP,shell(j)
the mathematical expression for each sub-segment in the boiling segment is:
ΔHshell,TP(j)＝Hshell,TP(j+1)-Hshell,TP(j)
according to the law of conservation of energy, the method comprises the following steps:
ΔHshell,TP＝ΔHtube,TP＝∑ΔHTP,shell(j)＝∑ΔHtube,TP(j)
ΔHTP,shell(j)＝ΔHtube,TP(j)＝KTP(j)ATP(j)ΔTln,TP(j)
each sub-segment of the shell side boiling section has a convective heat transfer coefficient (h)TP,shell(j) Calculating the Barbe correlation, convective heat transfer coefficient (h) of the tube pass sub-segmentsco,weight,L) And (3) for the tube side weighted average heat exchange coefficient, the mathematical expression of the total heat exchange coefficient of each sub-segment of the boiling section is as follows:
Figure FDA0002905380050000061
wherein Hshell,BEnthalpy corresponding to the shell-side bubble point temperature, Hshell,DEnthalpy corresponding to shell side dew point temperature, Hshell,inEnthalpy corresponding to the shell side inlet temperature, Hshell,outEnthalpy corresponding to outlet temperature, Δ Hshell,LChange in enthalpy, Δ H, corresponding to the shell-side liquid phase segmentshell,GChange in enthalpy, Δ H, corresponding to the shell-side gas phase sectionshell,TPChange in enthalpy, Δ H, corresponding to the shell boiling stageshell,TP(j) For each sub-segment of the enthalpy change, H, in the shell-side boiling segmentshell,TP(j) The enthalpy value of each subsection temperature demarcation point in the shell side boiling section; htube,BEnthalpy value corresponding to the tube pass bubble point temperature, Htube,DEnthalpy corresponding to shell side dew point temperature, Δ Htube,TPChange in enthalpy, Δ H, corresponding to the shell boiling stagetube,TP(j) For each sub-segment of the enthalpy change, H, in the shell-side boiling segmenttube,TP(j) Temperature demarcation for each subsection in tube side condensation sectionThe enthalpy of the spot.
9. The design method of a shell side boiling tube side condensing wound tube heat exchanger according to claim 2, wherein the heat exchange amount and the total heat transfer coefficient are known, and the calculation method of the heat exchange area is as follows:
AL＝ΔHshell,L/(KL·ΔTln,L)
AG＝ΔHshell,G/(KG·ΔTln,G)
ATP,tot＝∑ATP(j)＝ΔHshell,TP(j)/[KTP(j)·ΔTln,TP(j)]
wherein A isLIs the heat exchange area of the liquid phase section; a. theGIs the heat exchange area of the gas phase section; a. theTP,totIs the total heat exchange area of the boiling section; a. theTP(j) Is the heat exchange area of each sub-section in the boiling section. Before calculating the heat exchange area, a function between the heat exchange area and the geometric parameters is established according to the mathematical relationship between the geometric structure parameters of the wound tube type heat exchanger, and a functional relationship between the heat exchange area A and the length E is established: a ═ f (e), dA ═ f (de); and initializing the calculation of the heat exchange area.
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CN107992662A (en) * 2017-11-27 2018-05-04 郑州云海信息技术有限公司 The backwards calculation method of gravity assisted heat pipe air-conditioning system optimization design and variable working condition parameter
CN112052550A (en) * 2019-06-05 2020-12-08 无锡化工装备股份有限公司 Design method of shell side boiling spiral wound tube type heat exchanger
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CN107992662A (en) * 2017-11-27 2018-05-04 郑州云海信息技术有限公司 The backwards calculation method of gravity assisted heat pipe air-conditioning system optimization design and variable working condition parameter
CN112052550A (en) * 2019-06-05 2020-12-08 无锡化工装备股份有限公司 Design method of shell side boiling spiral wound tube type heat exchanger
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