CN105425584A - Pressure loss detection method of heat collection pipe network - Google Patents

Abstract

The present invention discloses a pressure loss detection method of a heat collection pipe network, belonging to the technical field of solar thermal power generation. The method comprises a step of simplifying a solar thermal power generation system heat collection field pipe network as a resistance network, a step of allowing the resistance factors of two solar heat collection array loops in the mother pipe in the heat collection field pipe network to be equivalent to R2, allowing the pipe on-way resistance factors between a cold oil mother pipe and a hot coil mother pipe as R1 and R3, and forming an infinite network by an infinite pipeline loop, a step of calculating the on-way pressure drop in the pipeline, calculating the friction resistance factor of each segment of the pipeline, and obtaining the resistance value in the resistance network, a step of obtaining the pressure loss value of the heat collection pipe network in the solar thermal power generation heat collection field pipe network according to the resistance value in the resistance network. Through the pressure loss equivalent calculation of a solar thermal power generation infinite pipe network, the accuracy of solar thermal power generation system modeling data is greatly improved, the data bias is reduced, and the control stability of the solar thermal power generation system is ensured.

Description

A kind of crushing detection method of thermal-arrest pipe network

Technical field

The present invention relates to photo-thermal power generation technical field, particularly relate to a kind of crushing detection method of thermal-arrest pipe network.

Background technology

Serious along with environmental pollution, the energy day by day exhausted, the developed countries such as generation of electricity by new energy market starts to come into one's own in countries in the world and widespread use, especially American-European.Along with the development of new forms of energy, photo-thermal power generation also starts day by day to emerge, and especially in photo-thermal energy developed countries such as Germany, Spain, China also starts progressively to develop photo-thermal power generation industry than more rich country as the solar illuminating energy.But due to the impact of environmental factor, also there is an a lot of difficult problem in solar-thermal generating system, especially calculate in data at some, computational accuracy is poor, can not reach accurate impression, thus causing control effects deviation comparatively large, system cloud gray model can be greatly affected, less stable.

Publication number is CN103439084A, publication date is that the Chinese patent literature on Dec 11st, 2013 discloses a kind of groove type solar condensing thermal power generation station condenser collecting efficiency test analysis algorithm, this test analysis algorithm is according to test data, by least square fitting curve, draw the collecting efficiency of condenser and the relational expression of condenser import and export oil temperature, thus condenser collecting efficiency and curve map in whole service temperature range can be drawn.

Condenser collecting efficiency test analysis algorithm in groove type solar condensing thermal power generation station disclosed in this patent documentation, by test data in conjunction with least square fitting curve, can finally obtain condenser collecting efficiency and curve map, but, accurately cannot test and draw photo-thermal power generation infinite pipe network crushing data, in the control of solar-thermal generating system, effect deviation is larger, system cloud gray model can be greatly affected, and causes Systematical control less stable.

Summary of the invention

The present invention is in order to overcome the defect of above-mentioned prior art, a kind of crushing detection method of thermal-arrest pipe network is provided, the present invention passes through photo-thermal power generation infinite pipe network crushing Equivalent Calculation, greatly improve the precision of solar-thermal generating system modeling data, decrease data deviation, ensure that solar-thermal generating system control stiffness.

The present invention is achieved through the following technical solutions:

A crushing detection method for thermal-arrest pipe network, is characterized in that, comprise the steps:

A, by solar-thermal generating system heat collecting field pipe network simplify equivalence become resistance network;

B, the resistance factor in two solar energy heating array loops on pipe female in heat collecting field pipe network is equivalent to R2, the pipeline on-way resistance factor between cold oil mother pipe and upper two branch roads of deep fat mother pipe is respectively R1 and R3, and infinite conduit forms infinite network;

C, calculate in pipeline along journey pressure drop, and calculate the friction resistance factor of every section of pipeline, obtain the resistance value in resistance network;

D, draw the value of pressure loss of thermal-arrest pipe network in solar-thermal generating system heat collecting field pipe network according to the resistance value equivalence in resistance network.

Calculating formula is passed through along journey pressure drop in described step C in pipeline calculate, in formula, L is the length of pipeline, and D is internal diameter of the pipeline, and u is liquid stream average velocity, and ρ is oil density, and λ is frictional resistant coefficient.

In described step C, the friction resistance factor of every section of pipeline passes through calculating formula calculate.

In described step D, value of pressure loss Δ P passes through calculating formula $R_{ab}=\frac{1}{2}\[\sqrt{(r_1+r_3)(r_1+r_3+4r_2)}-r_1-r_2\]$ With Δ P=RQ ⁿcalculate, wherein, R, λ and n in each pipeline are constants, and R is an attribute of pipeline, and n value, Q is fluid flow.

Principle of the present invention is as follows:

The infinite conduit of heat collecting field pipe network forms an infinite network, is similar to the infinite networking in circuit, in circuit, $R_{ab}=\frac{1}{2}\[\sqrt{(r_1+r_3)(r_1+r_3+4r_2)}-r_1-r_2\]$ (formula 1)

In solar-thermal generating system heat collecting field pipe network thermal-arrest pipe network crushing computation process in, flow the basic continous that all must meet below and energy relationship:

A, the current entering any node must equal the current of this node;

B, each ducted flowing must meet the law of friction of single pipe;

The algebraic sum of the loss in head of c, any closed-loop path is necessary for zero.

Can listing condition 2 for every bar pipeline:

Δ P=RQ ⁿ(formula 2)

Here R and n in each pipeline is constant, and wherein R is an attribute of pipeline, and it is fluid flow that n generally gets 2, Q; When λ is constant, can calculate by formula (3) along journey pressure drop in circular pipe

$\mathrm{\Δ}P=\mathrm{\λ}\frac{L}{D}\frac{u^2}{2}\mathrm{\ρ}$ (formula 3)

The length (m) of L-pipeline in formula; D-internal diameter of the pipeline (m); U-liquid stream average velocity (m/s); ρ-oil density (kg/m ³); λ-frictional resistant coefficient;

And will bring in formula (2) can draw with formula (3):

$R=\frac{8\mathrm{\λ}L}{{\mathrm{\π}}^2{D}^5}\·\mathrm{\ρ}$ (formula 4)

The friction resistance factor of every section of pipeline just can be calculated by formula (4).

The Reynolds number formula of pipe flow is: $\mathrm{Re}=\frac{ud}{v}$ (formula 5)

U-liquid stream average velocity (m/s); ν-liquid kinematic viscosity (m ²/ s); D-pipe diameter (m smooth pipe turbulent region experimental formula:

As 4000 < Re < 108, $\frac{1}{\sqrt{\mathrm{\&lambda;}}}=1.8\lg \left(\frac{\mathrm{Re}}{6.9}\right)$ (formula 6)

Coefficient of frictional resistance λ > 0 in pipeline, can rewrite formula (6) like this:

$\mathrm{\&lambda;}=\frac{1}{3.24{\lg }^2\left(\frac{\mathrm{Re}}{6.9}\right)}$ (formula 7)

The R drawn according to formula (4) is equivalent to the resistance in resistance network, then calculates the value of pressure loss at thermal-arrest networking by formula (1), (2).

Beneficial effect main manifestations of the present invention is in the following areas:

One, the present invention, " simplifies equivalence by solar-thermal generating system heat collecting field pipe network and becomes resistance network; The resistance factor in two solar energy heating array loops on pipe female in heat collecting field pipe network is equivalent to R2, and the pipeline on-way resistance factor between cold oil mother pipe and upper two branch roads of deep fat mother pipe is respectively R1 and R3, and infinite conduit forms infinite network; Calculate in pipeline along journey pressure drop, and calculate the friction resistance factor of every section of pipeline, obtain the resistance value in resistance network; The value of pressure loss of thermal-arrest pipe network in solar-thermal generating system heat collecting field pipe network is drawn according to the resistance value equivalence in resistance network "; by photo-thermal power generation infinite pipe network crushing Equivalent Calculation; greatly improve the precision of solar-thermal generating system modeling data; decrease data deviation; thus for selecting fluid power system to provide optimum Data support; ensure that the energy loss of system circuit is reduced to minimum, on this basis, just can ignore thermal-arrest pipe network crushing to the impact of Systematical control, ensure that solar-thermal generating system control stiffness.

Two, the present invention, the value of pressure loss at the thermal-arrest networking drawn by seven formula, simplify a lot of unnecessary intermediate variable, greatly reduce operand, compared with the computing networking value of pressure loss of routine, decrease the deviation accumulation caused due to too much intermediate operations link, thus make the present invention and test figure quite close, precision greatly improves, and is beneficial to and ensures solar-thermal generating system control stiffness.

Accompanying drawing explanation

Below in conjunction with specification drawings and specific embodiments, the present invention is described in further detail, wherein:

Fig. 1 is solar-thermal generating system heat collecting field pipe net arrangement structural representation of the present invention;

Fig. 2 is that thermal-arrest pipe network of the present invention simplifies isoboles;

Fig. 3 is the infinite resistance network figure of the present invention.

Embodiment

See Fig. 1-Fig. 3, a kind of crushing detection method of thermal-arrest pipe network, comprises the steps:

A, by solar-thermal generating system heat collecting field pipe network simplify equivalence become resistance network;

B, the resistance factor in two solar energy heating permutation loops on pipe female in heat collecting field pipe network is equivalent to R2, the pipeline on-way resistance factor between cold oil mother pipe and upper two branch roads of deep fat mother pipe is respectively R1 and R3, and infinite conduit forms infinite network;

C, calculate in pipeline along journey pressure drop, and calculate the friction resistance factor of every section of pipeline, obtain the resistance value in resistance network;

D, draw the value of pressure loss of thermal-arrest pipe network in solar-thermal generating system heat collecting field pipe network according to the resistance value equivalence in resistance network.

Calculating formula is passed through along journey pressure drop in described step C in pipeline calculate, in formula, L is the length of pipeline, and D is internal diameter of the pipeline, and u is liquid stream average velocity, and ρ is oil density, and λ is frictional resistant coefficient.

In described step C, the friction resistance factor of every section of pipeline passes through calculating formula calculate.

In described step D, value of pressure loss Δ P passes through calculating formula $R_{ab}=\frac{1}{2}\&lsqb;\sqrt{(r_1+r_3)(r_1+r_3+4r_2)}-r_1-r_2\&rsqb;$ With Δ P=RQ ⁿcalculate, wherein, R, λ and n in each pipeline are constants, and R is an attribute of pipeline, and n value gets 2.

The infinite conduit of heat collecting field pipe network forms an infinite network, is similar to the infinite networking in circuit, in circuit, $R_{ab}=\frac{1}{2}\&lsqb;\sqrt{(r_1+r_3)(r_1+r_3+4r_2)}-r_1-r_2\&rsqb;$ (formula 1)

In solar-thermal generating system heat collecting field pipe network thermal-arrest pipe network crushing computation process in, flow the basic continous that all must meet below and energy relationship:

A, the current entering any node must equal the current of this node;

B, each ducted flowing must meet the law of friction of single pipe;

The algebraic sum of the loss in head of c, any closed-loop path is necessary for zero.

Can listing condition 2 for every bar pipeline:

Δ P=RQ ⁿ(formula 2)

Here R and n in each pipeline is constant, and wherein R is an attribute of pipeline, and n generally gets 2, and wherein Q is fluid flow; When λ is constant, can calculate by formula (3) along journey pressure drop in circular pipe

$\mathrm{\&Delta;}P=\mathrm{\&lambda;}\frac{L}{D}\frac{u^2}{2}\mathrm{\&rho;}$ (formula 3)

The length (m) of L-pipeline in formula; D-internal diameter of the pipeline (m); U-liquid stream average velocity (m/s); ρ-oil density (kg/m ³); λ-frictional resistant coefficient;

And will bring in formula (2) can draw with formula (3):

$R=\frac{8\mathrm{\&lambda;}L}{{\mathrm{\&pi;}}^2{D}^5}\&CenterDot;\mathrm{\&rho;}$ (formula 4)

The friction resistance factor of every section of pipeline just can be calculated by formula (4).

The Reynolds number formula of pipe flow is: $\mathrm{Re}=\frac{ud}{v}$ (formula 5)

U-liquid stream average velocity (m/s); ν-liquid kinematic viscosity (m ²/ s); D-pipe diameter (m smooth pipe turbulent region experimental formula:

As 4000 < Re < 108, $\frac{1}{\sqrt{\mathrm{\&lambda;}}}=1.8lg\left(\frac{\mathrm{Re}}{6.9}\right)$ (formula 6)

Coefficient of frictional resistance λ > 0 in pipeline, can rewrite formula (6) like this:

$\mathrm{\&lambda;}=\frac{1}{3.24{\lg }^2\left(\frac{\mathrm{Re}}{6.9}\right)}$ (formula 7)

Pipeline parameter: according to the specification of heat collecting field design pipeline, the female pipe latus rectum of fuel feeding: 428.6mm; Conduction oil heat pipe latus rectum: 477.8mm; The thermal-collecting tube length in every bar loop is 576m, thermal-collecting tube latus rectum: 67mm; Thermal-collecting tube and cold and hotly have the duct length between female pipe to be about 60m, latus rectum 52.5mm.Every bar loop has two row's collector brackets to be formed by connecting, and the spacing between two row's heat collectors is 17m, and heat collector self A/F is 5.76m, and the oil pipe spacing between such two loops is 45.52m.

Oil parameter: when 290 DEG C, density is 828kg/m3, and viscosity is 0.281cst; When 390 DEG C, density is 709kg/m3, and viscosity is 0.214cst.

Flow parameter: the mass rate of pipeline is 426.5t/h.

Tubing material: 20#, weldless steel tube.

Loop parameter: infinite loop, every bar loop 576m thermal-collecting tube.

The Reynolds number of conduction oil in each pipeline is calculated according to formula (5):

1) the conduction oil Reynolds number in cold oil pipeline: Re ₁=1.5 × 106 (flow velocity is about 1m/s)

2) the conduction oil Reynolds number in hot oil pipeline: Re ₂=2.1 × 106 (flow velocity is about 0.9m/s)

3) the conduction oil Reynolds number in thermal-arrest pipeline: Re ₃=3.0 × 105 (mean flow rate is about 1.1m/s)

4) the ducted conduction oil Reynolds number between thermal-collecting tube and the female pipe of cold and hot oil: Re ₄=3.8 × 105 (mean flow rate is about 1.8m/s)

The frictional resistant coefficient in each section of pipe can be calculated respectively according to formula (7):

1) the conduction oil resistance coefficient in cold oil pipeline: λ ₁=0.0108

2) the conduction oil resistance coefficient in hot oil pipeline: λ ₂=0.0102

3) the conduction oil resistance coefficient in thermal-arrest pipeline: λ ₃=0.0143

4) thermal-collecting tube and the cold and hot ducted conduction oil resistance coefficient had between female pipe: λ ₄=0.0137 so far, and the parameter according to formula (4) and each pipeline section calculates corresponding frictional resistance factor.

Pipeline section	L(m)	Dg(m)	λ	R	u(m/s)
						Cold pipe between two loops	45.52	0.4286	0.0108	28.4ρ	1
Heat pipe between two loops	45.52	0.4778	0.0102	15.0ρ	0.9
						Thermal-collecting tube	576	0.067	0.0143	4.8×106ρ	1.1
Pipeline between thermal-collecting tube and hot and cold tube	60	0.0525	0.0137	1.7×106ρ	1.8

Here the density p in R is variable, the unified conduction oil density (828kg/m getting 290 DEG C ³)

Calculating to infinite loop:

Bring the conduction oil friction resistance factor of each pipeline section into frictional resistance factor Rab that formula (1) can calculate whole pipe network, wherein on each female pipe fulcrum, have two loops to be connected in parallel, such resistance factor $R_2=\frac{1}{2}(4.8+1.7)\&times;{10}^6\mathrm{\&rho;}=3.25\&times;106\mathrm{\&rho;}$ $R_{ab}=\frac{1}{2}\&lsqb;\sqrt{(28.4+15)(28.4+15+4\&times;3.25\&times;{10}^6)}-28.4-15\&rsqb;\mathrm{\&rho;}\&ap;1.2\&times;104\mathrm{\&rho;}$

According to the principle of mass conservation, cold oil mother manages and in the female pipe of deep fat, conduction oil mass rate is equal is 426.5t/h; The average density of front and back is 0.7685t/m ³; Calculate average volumetric flow rate thus and be about 555m ³/ h=0.154m ³/ s.

Bring the average external volume flow of pipe network and resistance factor into crushing that formula (2) can calculate pipe network:

ΔP＝1.2×10 ⁴×0.154 ²ρ≈285×828Pa＝235980Pa。

Claims (4)

1. a crushing detection method for thermal-arrest pipe network, is characterized in that, comprise the steps:

A, by solar-thermal generating system heat collecting field pipe network simplify equivalence become resistance network;

B, the resistance factor in two solar energy heating array loops on pipe female in heat collecting field pipe network is equivalent to R2, the pipeline on-way resistance factor between cold oil mother pipe and upper two branch roads of deep fat mother pipe is respectively R1 and R3, and infinite conduit forms infinite network;

C, calculate in pipeline along journey pressure drop, and calculate the friction resistance factor of every section of pipeline, obtain the resistance value in resistance network;

D, draw the value of pressure loss of thermal-arrest pipe network in solar-thermal generating system heat collecting field pipe network according to the resistance value equivalence in resistance network.

2. the crushing detection method of a kind of thermal-arrest pipe network according to claim 1, is characterized in that: pass through calculating formula along journey pressure drop in described step C in pipeline calculate, in formula, L is the length of pipeline, and D is internal diameter of the pipeline, and u is liquid stream average velocity, and ρ is oil density, and λ is frictional resistant coefficient.

3. the crushing detection method of a kind of thermal-arrest pipe network according to claim 1, is characterized in that: in described step C, the friction resistance factor of every section of pipeline passes through calculating formula calculate.

4. the crushing detection method of a kind of thermal-arrest pipe network according to claim 1, is characterized in that: in described step D, value of pressure loss Δ P passes through calculating formula $R_{ab}=\frac{1}{2}\&lsqb;\sqrt{(r_1+r_3)(r_1+r_3+4r_2)}-r_1-r_2\&rsqb;$ With Δ P=RQ ⁿcalculate, wherein, R, λ and n in each pipeline are constants, and R is an attribute of pipeline, and it is fluid flow that n value gets 2, Q.