CN102542164A - Reinforced system thermal-hydraulic behavior simulation method - Google Patents

Abstract

The invention relates to a reinforced system thermal-hydraulic behavior simulation method. In the method, the equation for solving the total heat-transfer coefficient K is added on the basis of three thermal load equations for solving existing simulation software, and variables q, tto, tso and K in the four equations are solved according to the determined information of type of heat exchangers and operating conditions thereof. The reinforced system thermal-hydraulic behavior simulation method overcomes the defect that solving precision is weakened or workload of users is increased when in use of the like software simulating heat exchange behavior of the heat exchangers, improves simulation accuracy and expands the simulation range and function of the like system thermal-hydraulic software.

Description

Enhanced system thermal-hydraulic Behavior modeling method

Technical field

The present invention relates to a kind of thermal-hydraulic Behavior modeling method.

Background technology

The software of existing simulation system thermal-hydraulic behavior has AFT Fathon and the Pipenet etc. of Flowmaster, the U.S. of Britain.These softwares are to simulate flow in the large-scale pipe network, pressure, Temperature Distribution and be celebrated.Flowmaster and AFT widely apply in the nuclear power field and promote at present, and the AP1000 power station of US Westinghouse company's exploitation also more adopts AFT that flow, the pressure distribution of system are predicted.Yet these softwares defective to some extent aspect simulation heat interchanger heat exchange behavior.Usually simulation heat interchanger heat exchange behavior comes down to find the solution following three equations:

q＝M _t·(C _p，ti·t _ti-C _p，to·t _to) (1)

q＝M _s·(C _p，so·t _so-C _p，si·t _si) (2)

$q=K\·(F\·\frac{(t_{\mathrm{ti}}-t_{\mathrm{so}})-(t_{\mathrm{to}}-t_{\mathrm{si}})}{\ln \frac{t_{\mathrm{ti}}-t_{\mathrm{so}}}{t_{\mathrm{to}}-t_{\mathrm{si}}}})\·A---\left(3\right)$

Wherein, q is a thermal load, kW; M is a mass rate, kg/s; T is a temperature, ℃; c _pBe specific heat at constant pressure, kJ/kg; F is the logarithm temperature difference correction factor of heat interchanger; K representes the overall heat transfer coefficient of heat interchanger; A representes total heat interchanging area, m ²Subscript: ti representes to manage side-entrance; To representes to manage side outlet; Si representes shell-side inlet; So representes the shell-side outlet; S representes shell-side; T representes to manage side.

In the above-mentioned parameter, relevant with heat transfer equipment body structure, pattern have a K, F, and A, relevant with the heat interchanger operating mode have q, M, a t _Ti, t _To, t _Si, t _So

Wherein, the overall heat transfer COEFFICIENT K is not only relevant with heat exchanger construction but also relevant with the heat interchanger operating mode.Usually finding the solution all is that the parameter relevant with heat exchanger construction obtains through consulting the design of heat exchanger drawing, the relevant parameter of given heat interchanger operating mode, and only remaining three variablees are found the solution.Below with q, t _To, t _SoFor being solved to example, known variables describes:

Because three unknown numbers and three nonlinear equations exist usually and confirm to separate, through the method acquisition numerical solution of tentative calculation and iteration.Because K is promptly relevant with heat exchanger construction relevant with the heat interchanger operating mode again, is not obtaining q, t _To, t _SoUnder the situation of these known variables, business software needs the given voluntarily K value of user usually or finds the K value to fit to funtcional relationship with the relation of operating mode, and then row is found the solution.Such solution has perhaps been lost the precision of finding the solution or has been increased user's workload.

Summary of the invention

The objective of the invention is to defective, a kind of enhanced system thermal-hydraulic Behavior modeling method is provided to prior art, with the accuracy of raising simulation, and the simulation context and the function of expansion similar system thermal-hydraulic software.

Technical scheme of the present invention is following: a kind of enhanced system thermal-hydraulic Behavior modeling method comprises following four simulation equations:

q＝M _t·(C _p，ti·t _ti-C _p，to·t _to) (1)

q＝M _s·(C _p，so·t _so-C _p，si·t _si) (2)

$q=K\·(F\·\frac{(t_{\mathrm{ti}}-t_{\mathrm{so}})-(t_{\mathrm{to}}-t_{\mathrm{si}})}{\ln \frac{t_{\mathrm{ti}}-t_{\mathrm{so}}}{t_{\mathrm{to}}-t_{\mathrm{si}}}})\·A---\left(3\right)$

$K=\frac{1}{[\frac{1}{h_s}+R_{\mathrm{fo}}+\frac{L_{\mathrm{tw}}{A}_o}{{\mathrm{\λ}}_w{A}_m}+(R_{\mathrm{fi}}+\frac{1}{h_t})\frac{A_o}{A_i}]}---\left(4\right)$

Wherein, q is a thermal load;

M is a mass rate;

T is a temperature;

c _pBe specific heat at constant pressure;

F is the logarithm temperature difference correction factor of heat interchanger;

K representes the overall heat transfer coefficient of heat interchanger;

A representes total heat interchanging area;

L _TwBe pipe thickness;

R _FoBe the heat-transfer pipe internal thermal resistance;

R _FiBe the heat-transfer pipe external thermal resistance;

H is a convection transfer rate;

λ _wBe the tube wall heat conduction coefficient;

A ₀For managing outer total heat conduction area, A _o=π Lr _o, L is a pipe range, r _oBe ips;

A _iFor managing interior total heat conduction area, A _i=π Lr _i, L is a pipe range, r _iBe ips;

A _mBe effective average heat transfer area;

Subscript: ti representes to manage side-entrance; To representes to manage side outlet; Si representes shell-side inlet; So representes the shell-side outlet; S representes shell-side; T representes to manage side;

Through heat interchanger pattern and the heat interchanger work information of confirming, find the solution the variable q in the above-mentioned equation, t _To, t _So

Further, aforesaid enhanced system thermal-hydraulic Behavior modeling method, wherein, described variable q, the t of finding the solution _To, t _SoProcess following:

(S1) confirm the pattern of heat interchanger;

(S2) confirm the heat interchanger work information;

(S3) give two and wait to separate variable t _ToOr t _SoOne of them initialize;

(S4) utilize equation (1-3) to calculate K, q simultaneously, and another variable t _SoOr t _To, the K that obtains is designated as K ₁

(S5) according to t _SoAnd t _To, try to achieve K through equation (4), be designated as K ₂

(S6) compare K ₂And K ₁If, | K ₂-K ₁|/K ₂Less than per mille, then finish to calculate, this calculates corresponding q, t _To, t _SoBe result of calculation; Otherwise, adjustment t _ToOr t _So, repeating step (S4).

Further, aforesaid enhanced system thermal-hydraulic Behavior modeling method wherein, in step (S6), needs adjustment t _ToThe time, if K ₂/ K ₁Greater than 1, then reduce t _To, if K ₂/ K ₁Less than 1, then increase t _ToNeed adjustment t _SoThe time, if K ₂/ K ₁Less than 1, then reduce t _So, if K ₂/ K ₁Greater than 1, then increase t _So

Beneficial effect of the present invention is following: the present invention is in order to improve system's thermal-hydraulic simulation softward in the accuracy aspect the temperature simulation; Finding the solution on original three equations based; Increase solving equation (4) (being the K equation); Overcome the deficiency of this type of software, improved the accuracy of simulation, expanded the simulation context and the function of similar system thermal-hydraulic software in simulation heat interchanger heat exchange behavior.

Description of drawings

Fig. 1 finds the solution variable q in the simulation equation, t for the present invention _To, t _So, the method flow diagram of K.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is carried out detailed explanation.

Aspect the heat interchanger simulation, popular in the world design of heat exchanger software has two kinds of HTRI and HTFS.These heat transmission equipment special softwares need be imported detailed heat exchanger structure parameter, and the system designer need consult the large number quipments Engineering Documents and accomplish the parameter input service.Key is can't be coupled into line data with the thermal-hydraulic software for calculation to exchange the simulation of accomplishing the heat interchanger exchange capability of heat.And system's thermal-hydraulic software such as technical background are said, and the overall coefficient of heat transfer K of heat exchanging device needs hypothesis in the calculating, and can't carry out Solving Coupled with result of calculation.

For addressing the above problem, enhanced system thermal-hydraulic Behavior modeling method provided by the present invention comprises following four simulation equations:

q＝M _t·(C _p，ti·t _ti-C _p，to·t _to) (1)

q＝M _s·(C _p，so·t _so-C _p，si·t _si) (2)

$q=K\·(F\·\frac{(t_{\mathrm{ti}}-t_{\mathrm{so}})-(t_{\mathrm{to}}-t_{\mathrm{si}})}{\ln \frac{t_{\mathrm{ti}}-t_{\mathrm{so}}}{t_{\mathrm{to}}-t_{\mathrm{si}}}})\·A---\left(3\right)$

$K=\frac{1}{[\frac{1}{h_s}+R_{\mathrm{fo}}+\frac{L_{\mathrm{tw}}{A}_o}{{\mathrm{\λ}}_w{A}_m}+(R_{\mathrm{fi}}+\frac{1}{h_t})\frac{A_o}{A_i}]}---\left(4\right)$

Wherein, q is a thermal load, kW;

M is a mass rate, kg/s;

T is a temperature, ℃;

c _pBe specific heat at constant pressure, kJ/kg;

F is the logarithm temperature difference correction factor of heat interchanger;

K representes the overall heat transfer coefficient of heat interchanger;

A representes total heat interchanging area, m ²

L _TwBe pipe thickness, m;

R _FoBe heat-transfer pipe internal thermal resistance, m ²℃/W;

R _FiBe heat-transfer pipe external thermal resistance, m ²℃/W;

H is a convection transfer rate, W/m ²℃;

λ _wBe the tube wall heat conduction coefficient;

A ₀For managing outer total heat conduction area, m ²A _o=π Lr _o(L is a pipe range, r _oBe ips)

A _iFor managing interior total heat conduction area, m ²A _i=π Lr _i(L is a pipe range, r _iBe ips)

A _mBe effective average heat transfer area, m ²

Be heat-transfer pipe thermal resistance, m ²℃/W;

Subscript: ti representes to manage side-entrance; To representes to manage side outlet; Si representes shell-side inlet; So representes the shell-side outlet; S representes shell-side; T representes to manage side.

The present invention is finding the solution on original three equations based in order to improve system's thermal-hydraulic simulation softward in the accuracy aspect the temperature simulation, increases solving equation (4) (hereinafter referred K equation), has overcome the deficiency of this type of software in simulation heat interchanger heat exchange behavior.The user only needs input heat exchanger structural parameters, the parameter relevant with operating mode all to have computer self to find the solution when calculating beginning.Perhaps user for ease, program pin is to different user, and with required heat exchanger structure parameter in advance and programmatic binding, the user only needs heat exchanging device model to select, and configuring working condition can calculate voluntarily.With the pressurized-water reactor nuclear power plant is example: 50 heat interchanger are arranged in the nuclear island approximately, contact complicated heat exchanger for fear of the user, can be earlier the structural information of these 50 heat interchanger be solidificated in the K equation.The user is selecting heat interchanger, and actual is at the K equation of selecting the different heat exchangers of representative.Import some working conditions during calculating again, like high temperature side flow and temperature in, low temperature side flow and temperature in can accurately be calculated the outlet temperature of high low temperature side, realize the accurate prediction of heat exchanging device heat exchange behavior.

Describe below and find the solution variable q in the above-mentioned equation, t _To, t _SoProcess, as shown in Figure 1.

The first step, when beginning to calculate, the user can confirm voluntarily that selecting the heat interchanger pattern still is to define heat interchanger voluntarily, thereby confirms parameter F, A.

In second step, confirm the back input or transmit the heat interchanger work information, like the flow of cold and hot side and inlet temperature information etc., M, t by system's thermal-hydraulic software _Ti, t _SiShell-side is a cold side, and the pipe side is hot side.

In the 3rd step, give t _To(or t _So, two wait to separate variable one of them) initialize, in the present embodiment, t _ToInitial value equal t _Ti, t _SoInitial value equal t _Si, certainly, t _ToOr t _SoInitial value also can be at t _Ti, t _SiThe basis on do slightly and to transfer;

In the 4th step, utilize equation (1-3) to calculate K, q, t _So(or t _To), K is designated as K ₁

Need to prove the R that comprises in the equation (4) _Fo, R _Fi, h _s, h _tDeng being temperature t all _To, t _SoFunction, those skilled in the art can be referring to T.Kuppan work, money panegyric etc. is translated " design of heat exchanger handbook 220-223 page or leaf.Can confirm each parameter in the equation (4) through the reference device design data.

The 5th step is according to t _SoAnd t _To, try to achieve K through equation (4), be designated as K ₂

The 6th step, relatively K ₂And K ₁If, | K ₂-K ₁|/K ₂Less than per mille, then finish to calculate, this calculates corresponding q, t _To, t _SoBe result of calculation; Otherwise, adjustment t _To(or t _So), repeated for the 4th step.

Adjustment t _ToOr t _SoMethod following: need adjustment t _ToThe time, if K ₂/ K ₁Greater than 1, then reduce t _ToIf K ₂/ K ₁Less than 1, then increase t _ToNeed adjustment t _SoThe time, if K ₂/ K ₁Less than 1, then reduce t _SoIf K ₂/ K ₁Greater than 1, then increase t _So

Reduce or increase t _To(or t _So) amplitude can confirm that it is that unit adjusts t gradually that present embodiment is recommended the per mille with current temperature value according to actual conditions _To(or t _So), those skilled in the art also can set adjusting range as the case may be, to satisfy actual needs.

The present invention has increased and has found the solution overall heat transfer coefficient equation on three equations based of system's thermal-hydraulic software solving heat exchange device, has improved the accuracy of simulation, has expanded the simulation context and the function of similar system thermal-hydraulic software.

Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, belong within the scope of claim of the present invention and equivalent technology thereof if of the present invention these are revised with modification, then the present invention also is intended to comprise these changes and modification interior.

Claims (7)

1. enhanced system thermal-hydraulic Behavior modeling method comprises following four simulation equations:

q＝M _t·(C _p，ti·t _ti-C _p，to·t _to) (1)

q＝M _s·(C _p，so·t _so-C _p，si·t _si) (2)

$q=K\·(F\·\frac{(t_{\mathrm{ti}}-t_{\mathrm{so}})-(t_{\mathrm{to}}-t_{\mathrm{si}})}{\ln \frac{t_{\mathrm{ti}}-t_{\mathrm{so}}}{t_{\mathrm{to}}-t_{\mathrm{si}}}})\·A---\left(3\right)$

$K=\frac{1}{[\frac{1}{h_s}+R_{\mathrm{fo}}+\frac{L_{\mathrm{tw}}{A}_o}{{\mathrm{\λ}}_w{A}_m}+(R_{\mathrm{fi}}+\frac{1}{h_t})\frac{A_o}{A_i}]}---\left(4\right)$

Wherein, q is a thermal load;

M is a mass rate;

T is a temperature;

c _pBe specific heat at constant pressure;

F is the logarithm temperature difference correction factor of heat interchanger;

K representes the overall heat transfer coefficient of heat interchanger;

A representes total heat interchanging area;

L _TwBe pipe thickness;

R _FoBe the heat-transfer pipe internal thermal resistance;

R _FiBe the heat-transfer pipe external thermal resistance;

H is a convection transfer rate;

λ _wBe the tube wall heat conduction coefficient;

A _oFor managing outer total heat conduction area, A _o=π Lr _o, L is a pipe range, r _oBe ips;

A _iFor managing interior total heat conduction area, A _i=π Lr _i, L is a pipe range, r _iBe ips;

A _mBe effective average heat transfer area;

Subscript: ti representes to manage side-entrance; To representes to manage side outlet; Si representes shell-side inlet; So representes the shell-side outlet; S representes shell-side; T representes to manage side;

Through heat interchanger pattern and the heat interchanger work information of confirming, find the solution the variable q in the above-mentioned equation, t _To, t _So

2. enhanced system thermal-hydraulic Behavior modeling method as claimed in claim 1 is characterized in that: described variable q, the t of finding the solution _To, t _SoProcess following:

(S1) confirm the pattern of heat interchanger;

(S2) confirm the heat interchanger work information;

(S3) give two and wait to separate variable t _ToOr t _SoOne of them initialize;

(S4) utilize equation (1-3) to calculate K, q simultaneously, and another variable t _SoOr t _To, the K that obtains is designated as K ₁

(S5) according to t _SoAnd t _To, try to achieve K through equation (4), be designated as K ₂

(S6) compare K ₂And K ₁If, | K ₂-K ₁|/K ₂Less than per mille, then finish to calculate, this calculates corresponding q, t _To, t _SoBe result of calculation; Otherwise, adjustment t _ToOr t _So, repeating step (S4).

3. enhanced system thermal-hydraulic Behavior modeling method as claimed in claim 2 is characterized in that: in step (S1), confirm parameter F, A according to the pattern of heat interchanger.

4. enhanced system thermal-hydraulic Behavior modeling method as claimed in claim 2 is characterized in that: in step (S2), confirm parameter M, t according to the heat interchanger work information _Ti, t _Si

5. enhanced system thermal-hydraulic Behavior modeling method as claimed in claim 4 is characterized in that: in step (S3), if give t _ToInitialize, its initial value equals t _TiIf give t _SoInitialize, its initial value equals t _Si

6. enhanced system thermal-hydraulic Behavior modeling method as claimed in claim 2 is characterized in that: in step (S6), need adjustment t _ToThe time, if K ₂/ K ₁Greater than 1, then reduce t _ToIf K ₂/ K ₁Less than 1, then increase t _To

7. enhanced system thermal-hydraulic Behavior modeling method as claimed in claim 2 is characterized in that: in step (S6), need adjustment t _SoThe time, if K ₂/ K ₁Less than 1, then reduce t _SoIf K ₂/ K ₁Greater than 1, then increase t _So

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