CN106369838A - Design method for parabolic trough solar heat collecting system - Google Patents

Abstract

The invention discloses a design method for a parabolic trough solar heat collecting system, comprising the steps of firstly, confirming the basic geometric structure of the heat collecting system and establishing a parameterized geometric model of a single heat collecting loop according to a local meteorological parameter, the geometric size of a heat collecting system mounting place and a system use condition; next, establishing a three-dimensional optical calculation model of the loop by using a Monte Carlo ray tracing method, and carrying out optical calculation to obtain the annual any-moment time-by-time comprehensive optical property of the loop; then, calculating the annual time-by-time comprehensive heat production property and annual total heat production of the single heat collecting loop by using a one-dimensional photothermal conversion calculation model for a loop heat collecting pipe; next, initially designing the total loop amount of the heat collecting system according to the design requirement for the annual total heat production of the system; and finally, initially designing the annual heat production of the heat collecting system through evaluating, and carrying out optimization calculation on the loop amount to finish the design of the heat collecting system. By using the design method, the structure and comprehensive photothermal property of the parabolic trough solar heat collecting system can be rapidly and effectively designed.

Description

A kind of slot light collection solar thermal collection system method for designing

Technical field

The invention belongs to light-focusing type solar utilizes technical field and in particular to a kind of slot light collection solar energy heating system System method for designing.

Background technology

Environmental problem that the increasingly depleted of fossil energy, utilization of energy bring and society fast-developing to energy demand Increase, require that renewable energy utilization technology is accelerated development in the whole world.In recent years, main energy sources big country has all put into effect a series of methods Laws ＆ Regulations and policies and measures, take action and accelerate the development and utilization of regenerative resource.Solar energy is rich reserves, cleans and can The regenerative resource extensively obtaining.In solar utilization technique, slot light collection heliotechnics is a kind of having a extensive future too Sun can heat utilization technology.Wherein, quick, efficient, the High Precision Automatic design of slot type collecting system and assessment are one and important grind Study carefully problem.

Light-concentrating solar heat-collection system mainly by multiple on the whole have can necessarily inclined by south-north direction and on east-west direction The thermal-arrest loop composition of the u shape arrangement at angle, each loop is in series by some groove type heat collectors, and each heat collector is mainly by groove Formula reflecting mirror and thermal-collecting tube (glass tubing outside main inclusion and internal metal heat absorption tube) and corresponding tracing control machine Structure forms.As a complicated solar energy converging and converting system, the design of slot type collecting system is involved in the reality of complexity Complicated solar energy converging collection process in border geography and meteorological factor, collecting system, the photo-thermal Coupled Heat Transfer Process in thermal-collecting tube, Efficiently and easily designing and assess its performance exactly will be very difficult.It is thus desirable to research one kind can quickly and effectively be carried out Slot light collection solar thermal collection system design and performance assessment, improve development efficiency, reduce development cost reasonable, science from Dynamicization method for designing.

Content of the invention

It is an object of the invention to provide one kind to efficiently accomplish slot light collection solar thermal collection system three-dimensional parameterized several What model, optical computing model and Calculation of Heat Transfer modelling, quickly and effectively carry out slot light collection solar thermal collection system knot Structure and comprehensive light thermal property design, solve the problems, such as the slot light collection solar thermal collection system method for designing of system Automated Design.

For reaching above-mentioned purpose, the technical solution adopted in the present invention is as follows:

1) determine annual quantity of heat production design requirement q of slot light collection solar thermal collection system to be designed_s,required, concrete Geo-location parameter and meteorological parameter information；Wherein, slot light collection solar thermal collection system to be designed is pressed on the whole by multiple South-north direction is simultaneously made up of the thermal-arrest loop of the u shape arrangement of drift angle on east-west direction, and each loop is by some groove type heat collectors In series, each heat collector is mainly made up of slot type reflecting mirror and thermal-collecting tube and tracing control mechanism；

2) determine the basic geometrical structure parameter of slot light collection solar thermal collection system to be designed, set up collection hot loop 3-D geometric model；

3) slot light collection solar thermal collector each component optical parameter and thermal physical property parameter, the hot physical property of heat-transfer working medium are determined Parameter；

4) determine inlet flow rate initial setting m in slot light collection solar energy heating loop_inWith out temperature setting value；

5) computing unit division is carried out to slot light collection solar energy heating loop, that is, with slot type collection hot loop by continuous The structure of n closely coupled groove type heat collector composition is computing unit, n >=1, and each computing unit after division is considered one Individual independent solar energy converging and photothermal deformation equipment；

6) solar energy converging process in computing unit is calculated: set up its light for computing unit 3-D geometric model Learn model, optical computing is carried out using Monte Carlo ray tracking method, obtain this computing unit in whole year by when optics The thermal power absorbing in real time in efficiency, heat absorption tube outer surface and glass tubing；

7) the photothermal deformation process in computing unit is calculated: for computing unit thermal-collecting tube Parametric geometric model Set up its one-dimensional photothermal deformation computation model, calculated using convection heat transfer' heat-transfer by convection, conduction heat transfer, radiant heat transfer computational methods, obtain Obtain this computing unit in whole year by when photo-thermal conversion efficiency, working medium caloric receptivity and outlet temperature；

8) repeat step 6) and step 7), to all computing units connected in slot light collection solar energy heating loop too Sun can converge and be solved step by step with photothermal deformation process, until be calculated the endothermic tube of last computing unit of loop Outlet parameter, calculated circuit outlet Temperature of Working is contrasted with circuit outlet design temperature, if the two differs 0.1% Within, then loop mass flow m now_inMeet design requirement；Otherwise then adjust m_inValue and calculated again, until Till circuit outlet temperature meets requirement；

9) by when calculate in whole year the single loop heat production power in each moment and by heat production power and this institute in calculating moment The single loop quantity of heat production that the time interval multiplication representing obtains in this time interval, then passes through the list in each time interval Individual loop quantity of heat production is added the annual quantity of heat production q obtaining single loop_l,design；

10) according to step 1) in heat collecting field whole year quantity of heat production design requirement q_s,requiredWith step 9) in single loop Annual quantity of heat production result of calculation estimates thermal-arrest loop quantity n needed for heat collecting field to be designed_l,design=q_s,required/q_l,design；Connect , according to step 2) in setting determine the thermal-arrest loop quantity of each subregion of heat collecting field；

11) it is directed to each of all subregions of heat collecting field loop and adopt step 5) to step 9) calculate the annual product in each loop Heat, and obtain collecting system whole year quantity of heat production q by being added each loop whole year quantity of heat production_s,design；

12) judge whether result of calculation meets design requirement by formula (1), if the annual quantity of heat production of the collecting system obtaining q_s,designMeet design requirement then to terminate；If being unsatisfactory for requiring, return to step 11 after the number of adjustment loop) continue to calculate, directly To meeting design requirement；

Described step 1) determine that geo-location parameter and meteorologic parameter include:

Heat collecting field local latitude to be designed, longitude and time zone data；Heat collecting field to be designed constant duration of local whole year by When meteorological data, described meteorological data include annual constant duration by when measurement obtain beam radia intensity, dry bulb Temperature, wind speed, wind direction and atmospheric pressure.

Described step 2) the basic geometrical structure parameter of slot light collection solar thermal collection system includes: single heat collector anti- Penetrate outer radius r in mirror Opening length l and width w, glass tubing and endothermic tube effective length l, glass tubing₄,r₅, endothermic tube inside and outside half Footpath r₂,r₃；Heat collecting field number of partitions and each subregion arranged thermal-arrest loop number account for the ratio of total loop number；Single thermal-arrest The heat collector number in loop, spacing d on Working fluid flow direction for each heat collector_1ine；Spacing d between each row of heat collector_row；

Set up collection hot loop 3-D geometric model to include: set up slot light collection solar energy heating loop using mathematic(al) representation Three-dimensional optical system three-dimensional parameterized geometric model, the expression formula of this Parametric geometric model includes the reflection of computing unit Mirror cylindrical equation, glass pipe outer wall face of cylinder equation, glass inside pipe wall face of cylinder equation and heat absorption pipe outer wall face of cylinder equation.

Described step 3) in determination heat collector optical parametric and thermal physical property parameter, the thermal physical property parameter bag of heat-transfer working medium Include:

Reflecting mirror, endothermic tube, the material of glass tubing, reflectance of reflector ρ_m, cleanliness factor ρ_soil, shape surface error standard deviation sigma_m, Glass tubing absorbance α_g, transmissivityτ_g, reflectivity ρ_gAnd refractive index θ_g, absorb heat pipe outer wall coating for selective absorption absorbance α₃, send out Penetrate rate ε₃, endothermic tube heat conductivity λ₂₃, glass tubing heat conductivity λ₄₅, the heat conductivity λ of heat-transfer working medium₁With specific heat capacity c_p.

Described step 6) solar energy converging process computational methods are as follows in computing unit:

Formula (2) and (3) 6-1) are adopted to calculate heat collector respectively and follow the tracks of angle beta_cWith incidence angle θ on heat collector for the sunlight,

${\mathrm{\β}}_c={\tan }^{-1}\left(\frac{cos\mathrm{\α}sin(a-a_c)}{sin(\mathrm{\α}-{\mathrm{\α}}_c)+{\mathrm{sin\α}}_{c}cos\mathrm{\α}(1-cos(a-a_c\left)\right)}\right)---\left(2\right)$

$\mathrm{\θ}={\cos }^{-1}\sqrt{1-{\[cos(\mathrm{\α}-{\mathrm{\α}}_c)-{\mathrm{cos\α}}_{c}cos\mathrm{\α}(1-cos(a-a_c\left)\right)\]}^2}---\left(3\right)$

In formula, α, a are respectively local true solar time t_sWhen sun altitude and azimuth, work as t_s< during 12h a be on the occasion of, Work as t_s> 12h when a be negative value；α_c,a_cIt is respectively inclination angle and the azimuth of heat collecting field, the South and the North is pressed in wherein each loop on the whole To arrangement and drift angle, α when with respect to the horizontal plane upwarping when loop southern side can be had on east-west direction_cBe on the occasion of, otherwise α_cIt is negative Value, and when loop southern side deflection east a_cBe on the occasion of, otherwise a_cFor negative value；

6-2) carry out communication process in computing unit for the solar radiation using Monte Carlo ray tracking method to calculate

Incident solar radiation is approximately the random light carrying identical energy in a large number；Light is on computing unit reflecting mirror Incoming position determined by equally distributed probabilistic model, that is, adopt formula (4) calculate often restraint light random order on the mirror Put p_m, wherein with computing unit mirror center as initial point, mirror length, width and center vertical line direction are respectively x, y, z Axle sets up reflecting mirror coordinate system, calculates the impact of the non-parallel angle of sunlight by the probabilistic model of non-uniform Distribution simultaneously, Wherein random ray relative is in the radial direction drift angle δ of incident beam primary optical axis_solWith circumferential bias angle theta_solPress formula (5) respectively to calculate；Connect The impact considering incidence angle θ on heat collector for the sunlight, that is, obtain sunlight incident direction vector under reflecting mirror coordinate system i_m；

p_m=[nl (ξ₁-0.5) nw(ξ₂-0.5) f(y)]^t(4)

${\mathrm{\&delta;}}_{sol}={\sin }^{-1}\left(\sqrt{{\mathrm{\&xi;}}_3{\sin }^2\mathrm{\&delta;}}\right),{\mathrm{\&theta;}}_{sol}=2{\mathrm{\&pi;\&xi;}}_4---\left(5\right)$

In formula, f (y) is groove type heat collector section type equation with parabolic form；N is the heat collector number in computing unit；L and w It is respectively the length and width of each heat collector reflecting mirror, m；δ is 1/2nd, rad of solar apparent diameter；

6-3) sunray and computing unit each component optical mechanism calculate

Judge whether light is blocked by adjacent groove type heat collector；If not being blocked, continue to calculate light and groove type heat collector Reflecting mirror, glass tubing, the intersection point of endothermic tube, judge the optics mistake of reflection at each part for the light, refraction and absorption meanwhile Journey；

6-3-1) when light reaches mirror surface, to judge whether to reflect by formula (6), if there is transmitting, To calculate the reflective vector r of light by formula (7)_m；Wherein, mirror mirror actual normal vector n_mConsider reflecting mirror shape face by mistake Difference standard deviation sigma_mImpact to reflection process, n_mRadial direction δ with respect to preferable normal vector_rWith circumferential bias angle theta_rUsing formula (8) meter Calculate；

0≤ξ₅＜ ρ_m·ρ_soil, reflect (6)

r_m=2 (i_m·n_m)n_m-i_m(7)

${\mathrm{\&delta;}}_r={\sin }^{-1}\left(\sqrt{{\mathrm{\&xi;}}_6{\sin }^2{\mathrm{\&sigma;}}_m}\right),{\mathrm{\&theta;}}_r=2{\mathrm{\&pi;\&xi;}}_7---\left(8\right)$

ρ in formula_m,ρ_soilIt is respectively reflectance of reflector, cleanliness factor；

6-3-2) when light reaches glass tube exterior surface, to judge the optical effect mode of light by formula (9), if light Absorbed, count absorbed energy and record its absorption position；If there is refraction, calculated in glass using the light law of refraction The vectorial re of refraction_o；Vectorial re in the refracting process of glass pipe internal surface and after being reflected for the light is calculated using identical method_i； After light reaches heat absorption tube outer surface, ray optics model of action is judged by formula (10), if light is absorbed, statistics is inhaled Receive energy and record absorption position；If light is diffusely reflected, calculate the diffuse-reflectance vector r on endothermic tube using blue Bei Tedinglv_c；

0≤ξ₈＜ τ_g, refraction；τ_g≤ξ₈＜ 1- ρ_g, absorb；1-ρ_g≤ξ₈≤ 1, reflect (9)

0≤ξ₈＜ α₃, absorb；ξ₈≥α₃, diffuse-reflectance (10)

τ in formula_g,ρ_gIt is respectively glass tubing absorbance, reflectance；α₃For the pipe outer wall coating for selective absorption absorbance that absorbs heat；

6-3-3) next proceed to calculate heat absorption tube outer surface to diffuse the intersection point of line and glass pipe internal surface, adopt simultaneously Judge its optical effect process with formula (9) and adopt step 6-3-1)～6-3-2) described in method continue to light calculate single Communication process in unit carries out calculating until light is absorbed or reflected and loses；Ideal is obtained according to the final statistics of above-mentioned calculating Solar power q being absorbed with each calculating moment in glass tubing on endothermic tube under state_3,i,q_45,i, and obtain computing unit Perfect optics efficiency value η at this moment_opt,i, it is defined as q_3,iWith institute's energy in notch type reflecting mirror aperture area during this calculating The ratio of the maximum solar power receiving；

6-4) last, consider further due to sunlight in the angle of incidence of reflecting mirror plane of the opening caused by computing unit end End optical loss/income coefficient η_end, the glass tubing reflection optics that caused due to non-perpendicular transmission on glass tubing for the sunlight damaged Losing coefficient is incident angle modifier η_iam, heat collector tracking error coefficient η_track, other synthetic error coefficient η_generalTo computing unit The impact of optical efficiency, is calculated computing unit actual optical efficiency η at this moment using formula (11)_opt；Adopt formula (12) simultaneously Can be calculated computing unit heat absorption pipe outer wall actual absorption solar power q₃, glass tubing actual absorption solar power q₄₅；

η_opt=η_opt,i·η_end·η_iam·η_track·η_general(11)

q₃=q_3,i·η_end·η_iam·η_track·η_general,q₄₅=q_45,i·η_end·η_iam·η_track·η_general(12)

In calculating formula, each ξ all represents one and obeys equally distributed random number in (0,1) is interval, and all with Machine number is separate；

In the calculation, the numeral in physical quantity subscript represents each structure respectively and corresponds to parameter, wherein 1- heat absorption intraductal working medium, 2- heat absorption inside pipe wall, 3- heat absorption pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding air, 7- surrounding, meanwhile, The subscript of physical parameter and dust suppression by spraying represents the qualitative temperature of its structure being adopted, ε₃Represent heat absorption pipe outer wall with t₃It is fixed The emissivity of degree warm in nature, λ₄₅Represent glass tubing with internal and external walls mean temperature t₄₅=(t₄+t₅)/2 are the heat conductivity of qualitative temperature.

Described step 7) computing unit in photothermal deformation process computational methods as follows:

7-1) in the endothermic tube of computing unit, single-phase convection heat exchange power calculating formula and import and export energy conservation equation formula are divided Wei not formula (13) and formula (14)；

q₁₂=2 π r₂nlh₁₂(t₂-t₁),h₁₂=nu₁₂λ₁/(2r₂),t₁=(t_out+t_in)/2 (13)

q₁₂=m_in(c_p,outt_out-c_p,int_in) (14)

In formula, m_inFor tube inlet working medium mass flow of absorbing heat, kg m^-1；t_in,t_outIt is respectively computing unit endothermic tube to enter Outlet Temperature of Working, k；t₁,t₂It is respectively and import and export working medium mean temperature and heat absorption inside pipe wall mean temperature, k；c_p,in,c_p,outPoint Do not import and export working medium specific heat capacity, j (kg k) for computing unit endothermic tube^-1；r₂For the bore that absorbs heat, m；

According to different heat absorption Bottomhole pressure Reynolds number re₁, Prandtl number pr₁Draw ratio with endothermic tube in computing unit Select heat convection correlation in different endothermic tubes；

Laminar convection Heat transfer corelation:

nu₁₂=4.3636 (15)

The formula scope of application is re₁<2300；

Dittus-boelter formula:

${\mathrm{nu}}_{12}=0.023{\mathrm{re}}_1^{0.8}{\mathrm{pr}}_1^c---\left(16\right)$

The formula scope of application is, c=0.4 during heating fluid, c=0.3, re during cooling fluid₁=10⁴～1.2 × 10⁵, pr₁=0.7～120, draw ratio nl/ (2r₂)≥60；L is the length of every endothermic tube, m；

Gnielinski formula:

${\mathrm{nu}}_{12}=\frac{(f/8)({\mathrm{re}}_1-1000){\mathrm{pr}}_1}{1+12.7\sqrt{f/8}({\mathrm{pr}}_1^{2/3}-1)}\&lsqb;1+{\left(\frac{2r_2}{nl}\right)}^{2/3}\&rsqb;\&centerdot;{\left(\frac{{\mathrm{pr}}_1}{{\mathrm{pr}}_2}\right)}^{0.01}---\left(17\right)$

The formula scope of application is pr₁/pr₂=0.05～20, re₁=2300～10⁶,pr₁=0.6～10⁵；

Resistance coefficient in gnielinski formula adopts filonenko formula to calculate:

F=(1.82lgre₁-1.64)^-2(18)

The formula scope of application is re₁=2300～10⁶, pr₁=0.6～10⁵；

7-2) the heat conduction power calculation between heat absorption pipe outer wall and inwall

q₂₃=2 π λ₂₃nl(t₃-t₂)/ln(r₃/r₂) (19)

7-3) radiant heat transfer between heat absorption pipe outer wall and glass inside pipe wall calculates

$q_{34}=2{\mathrm{\&pi;r}}_{3}nl\mathrm{\&sigma;}(t_3^4-t_4^4)/\&lsqb;\frac{1}{{\mathrm{\&epsiv;}}_3}+\frac{r_3}{r_4}(\frac{1}{{\mathrm{\&epsiv;}}_4}-1)\&rsqb;---\left(20\right)$

In formula, σ is black body radiation constant, w (m²·k⁴)^-1；

7-4) calculated by the heat flow of glass tubing surfaces externally and internally

$q_4=\frac{2{\mathrm{\&pi;\&lambda;}}_{45}nl}{ln(r_5/r_4)}(t_4-t_5)+q_{45}(\frac{r_4^2}{r_5^2-r_4^2}-\frac{1}{2ln(r_5/r_4)})---\left(21\right)$

$q_5=\frac{2{\mathrm{\&pi;\&lambda;}}_{45}nl}{ln(r_5/r_4)}(t_4-t_5)+q_{45}(\frac{r_5^2}{r_5^2-r_4^2}-\frac{1}{2ln(r_5/r_4)})---\left(22\right)$

7-5) the heat convection between glass pipe outer wall and air, and the calculation of radiation heat transferring and surrounding between

$q_{567}=2{\mathrm{\&pi;r}}_5{\mathrm{nlh}}_{56}(t_5-t_6)+2{\mathrm{\&pi;r}}_5{\mathrm{nl\&sigma;\&epsiv;}}_5(t_5^4-t_7^4),h_{56}={\mathrm{nu}}_{56}{\mathrm{\&lambda;}}_{56}/\left(2r_5\right)---\left(23\right)$

According to different Rayleigh numbers ra₅₆, Reynolds number re₅₆, Prandtl number pr₅₆Change Deng selecting the outer convection current of different glass tubings Hot correlation；

Calm free convection churchill-chu formula:

${\mathrm{nu}}_{56}=0.68+0.67{\mathrm{ra}}_{56}^{0.25}/{\&lsqb;1+{(0.492/{\mathrm{pr}}_{56})}^{9/16}\&rsqb;}^{4/9}---\left(24\right)$

The formula scope of application is ra₅₆＜ 10⁹,re₅₆≤1；

Eckert-drake formula:

${\mathrm{nu}}_{56}=(0.43+0.5{\mathrm{re}}_{56}^{0.5}){\mathrm{pr}}_{56}^{0.38}{\left(\frac{{\mathrm{pr}}_6}{{\mathrm{pr}}_5}\right)}^{0.25}---\left(25\right)$

The formula scope of application is re₅₆=1～10³；

Churchill-bernstein formula:

${\mathrm{nu}}_{56}=0.3+\frac{0.62{\mathrm{re}}_{56}^{0.5}{\mathrm{pr}}_{56}^{1/3}}{{\&lsqb;1+{(0.4/{\mathrm{pr}}_{56})}^{2/3}\&rsqb;}^{1/4}}{\&lsqb;1+{\left(\frac{{\mathrm{re}}_{56}}{282000}\right)}^{5/8}\&rsqb;}^{0.8}---\left(26\right)$

The formula scope of application is re₅₆=10³～10⁷,pe₅₆>0.2.

Described step 8) in in slot light collection solar energy heating loop series connection all computing units solar energy converging As follows with the method that photothermal deformation process is solved step by step:

8-1) according to law of conservation of energy, establishment step 7) in each heat flow between equilibrium equation:

q₂₃=q₁₂,q₃₄=q₃-q₂₃,q₄=q₃₄,q₅=q₅₆₇(27)

8-2) pass through simultaneous equations (13)～(27), in known air temperature t₆, ambient temperature t₇, computing unit import work Matter temperature t_inWith flow m_inIn the case of, obtain computing unit outlet Temperature of Working t_out, wall temperature t inside and outside endothermic tube₂,t₃, glass Wall temperature t inside and outside pipe₄,t₅, each heat flow value q₁₂,q₂₃,q₃₄,q₄,q₅,q₅₆₇；

8-3) the parameter transmission between each computing unit in loop

In the hot loop of a collection, comprise multiple computing units from circuit entrance to circuit outlet, each is calculated single Unit, its sender property outlet parameter is the suction parameter of next computing unit, and the suction parameter of initial unit is equal to loop and absorbs heat The suction parameter of pipe, the outlet parameter of last computing unit is equal to the outlet parameter of whole loop endothermic tube；

Described step 12) in adjustment feeder number purpose method such as formula (28):

$n_{l,design}^{\&prime;}=\left\{\begin{array}{c}{n}_{l,design}-1,(q_{s,design}-q_{s,required})>q_{s,design}/n_{l,design}\\ n_{l,design}+1,(q_{s,design}-q_{s,required})<-q_{s,design}/n_{l,design}\end{array}\right.---\left(28\right)$

Loop number after wherein adjusting is n '_l,design.

Table 1 gives the list of used parameter in this slot light collection solar thermal collection system method for designing.Wherein, physics Numeral in amount subscript represents parameter corresponding to each structure of heat collector respectively, i.e. 1- heat absorption intraductal working medium, 2- heat absorption inside pipe wall, 3- Heat absorption pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding air, 7- surrounding, such as t₃Put down for heat absorption pipe outer wall All temperature.Meanwhile, the subscript of physical parameter and dust suppression by spraying represents the qualitative temperature of its adopted structure, such as ε₃Represent heat absorption Pipe outer wall is with t₃For the emissivity of qualitative temperature, λ₄₅Represent glass tubing with internal and external walls mean temperature t₄₅=(t₄+t₅)/2 are fixed The heat conductivity of degree warm in nature.

The present invention compares traditional method for designing advantage and is:

(1) the invention provides a kind of multiple subject such as meteorology, geometric optics, hydrodynamics and thermal conduction study that combines The overall annual synthesis solar collecting performance assessment of slot light collection solar thermal collection system and automatic design method.

(2) method for designing of the present invention has extremely strong versatility it is adaptable to global anywhere, the heat collecting field in various orientation Arrangement, various types of slot light collection solar thermal collector.

(3) method for designing computational accuracy of the present invention and computational efficiency height, intelligent and high degree of automation, can make designer Quickly and efficiently complete slot light collection solar energy system geometric model, optical computing model and Calculation of Heat Transfer modelling, and base In this efficiently and rapidly assessment of completion system whole year performance and calculating, thus realizing automatically setting of slot light collection solar energy system Meter.The method has important directive significance and engineering application value for the design of slot light collection solar energy system and optimization.

Table 1 is slot light collection solar thermal collection system method for designing parameter list.

Brief description

Fig. 1 is slot light collection solar thermal collection system structural representation.

Fig. 2 is groove type heat collector structural representation.

Reference: 1, heat-transfer working medium, 2, heat absorption inside pipe wall, 3, heat absorption pipe outer wall, 4, glass inside pipe wall, 5, outside glass tubing Wall, 8, reflecting mirror, 11, groove type heat collector, 12, u-shaped collection hot loop, 13, thermal energy storage and modular converter, 14, heat collecting field subregion

Specific embodiment

The method for designing step of the present invention is as follows:

1) annual quantity of heat production design requirement, the particular geographic location of slot light collection solar thermal collection system to be designed are determined Parameter and meteorological parameter information；

Determine heat collecting field whole year quantity of heat production design load q according to design requirement_s,required.Input heat collecting field to be designed and work as ground weft Degree, longitude, time zone data.Input heat collecting field to be designed constant duration of local whole year by when meteorological data；Described meteorological data Main include annual constant duration by when measurement obtain beam radia intensity, dry-bulb temperature, wind speed, wind direction, air Pressure etc..

2) determine the basic geometrical structure parameter of slot light collection solar thermal collection system (referring to Fig. 1) to be designed, set up Loop parameter geometric model；

Determine the geometric parameter of each heat collector (referring to Fig. 2) according to the type of groove type heat collector, including reflecting mirror opening Outer radius r in length l and width w, glass tubing and endothermic tube effective length l, glass tubing₄,r₅, outer radius r in endothermic tube₂,r₃； Arrange that orientation and actual place physical dimension determine heat collecting field number of partitions and the arranged collection of each subregion according to slot type Jing Chang Hot loop number accounts for the ratio of total loop number；Determine collection hot loop geometry, that is, determine each loop heat collector number, Spacing d on Working fluid flow direction for each heat collector_1ine；Finally, setting is required according to heat collector geometric parameter and safe operation Spacing parameter d between each row of heat collector_row；Finally slot light collection solar energy heating loop optics is set up using mathematic(al) representation The three-dimensional parameterized geometric model of system, the expression formula of this Parametric geometric model mainly includes the reflecting mirror cylinder of computing unit Equation, glass pipe outer wall face of cylinder equation, glass inside pipe wall face of cylinder equation, heat absorption pipe outer wall face of cylinder equation.In the calculation, Numeral in physical quantity subscript represents each structure respectively and corresponds to parameter, and wherein 1- heat absorption intraductal working medium, 2- heat absorption inside pipe wall, 3- inhale Heat pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding air, 7- surrounding.

3) slot light collection solar thermal collector optical parametric and thermal physical property parameter, the thermal physical property parameter of heat-transfer working medium are determined；

Determine the reflecting mirror of groove type heat collector, endothermic tube, the material of glass tubing, reflectance of reflector ρ_m, cleanliness factor ρ_soil、 Shape surface error standard deviation sigma_m, glass tubing absorbance, absorbance, reflectance and refractive index α_g,τ_g,ρ_g,θ_g, absorb heat pipe outer wall selectivity Absorber coatings absorbance α₃, emissivity ε₃, endothermic tube heat conductivity λ₂₃, glass tubing heat conductivity λ₄₅, the heat conduction system of heat-transfer working medium Number λ₁With specific heat capacity c_p.Wherein, the subscript of physical parameter represents the qualitative temperature of its part being adopted, such as ε₃Represent endothermic tube Outer wall is with t₃For the emissivity of qualitative temperature, λ₄₅Represent glass tubing with internal and external walls mean temperature t₄₅=(t₄+t₅)/2 are qualitative The heat conductivity of temperature.Set up the ginseng of the three-dimensional geometrical structure of the three-dimensional optical system of slot type computing unit using mathematic(al) representation Numberization model, the expression formula of this Parametric geometric model mainly includes the reflecting mirror cylindrical equation of computing unit, glass pipe outer wall Face of cylinder equation, glass inside pipe wall face of cylinder equation, heat absorption pipe outer wall face of cylinder equation.

4) determine light-concentrating solar heat-collection loop operational factor；

Actually used operating mode according to slot type heat collecting field and groove type heat collector type, loop length etc., determine collection hot loop Inlet flow rate initial setting m_in, out temperature setting value.

5) computing unit division is carried out to light-concentrating solar heat-collection loop；

With slot type collection hot loop for calculating object, to be made up of continuous n closely coupled groove type heat collector in loop Structure be computing unit (n >=1), each computing unit after division can be considered as an independent solar energy converging and photo-thermal Conversion equipment.

6) solar energy converging process in computing unit is calculated；

For computing unit 3-D geometric model, its three-dimensional optical model is set up using Monte Carlo ray tracking method, and Carry out optical computing, obtain the thermal power absorbing in real time in optical efficiency, heat absorption tube outer surface and the glass tubing of this computing unit.Meter In calculation, each ξ all represents one and obeys equally distributed random number in (0,1) is interval, and all randoms number are separate.

6-1) first, heat collector is calculated using following formula and follow the tracks of angle beta_cWith incidence angle θ on heat collector for the sunlight:

${\mathrm{\&beta;}}_c={\tan }^{-1}\left(\frac{cos\mathrm{\&alpha;}\sin (a-a_c)}{\sin (\mathrm{\&alpha;}-{\mathrm{\&alpha;}}_c)+{\mathrm{sin\&alpha;}}_{c}cos\mathrm{\&alpha;}(1-cos(a-a_c\left)\right)}\right)---\left(1\right)$

$\mathrm{\&theta;}={\cos }^{-1}\sqrt{1-{\&lsqb;cos(\mathrm{\&alpha;}-{\mathrm{\&alpha;}}_c)-{\mathrm{cos\&alpha;}}_{c}cos\mathrm{\&alpha;}(1-cos(a-a_c\left)\right)\&rsqb;}^2}---\left(2\right)$

In formula, α, a are respectively local true solar time t_sWhen sun altitude and azimuth, work as t_s< during 12h a be on the occasion of, Work as t_s> 12h when a be negative value；α_c,a_cIt is respectively inclination angle and azimuth (referring to Fig. 1) of heat collecting field, wherein each loop is overall On by North and South direction arrangement and certain drift angle, α when therefore with respect to the horizontal plane upwarping when loop southern side can be had on east-west direction_c Be on the occasion of, otherwise α_cFor negative value, and a when loop southern side deflection east_cBe on the occasion of, otherwise a_cFor negative value.

6-2) then, carry out communication process in computing unit for the solar radiation to calculate, incident solar radiation is approximately Carry the random light of identical energy in a large number；Incoming position on computing unit reflecting mirror for the light is by equally distributed probability mould Type determines, that is, adopt formula (3) to calculate often and restraint light random site p on the mirror_m, wherein with computing unit mirror center For initial point, mirror length, width and center vertical line direction are respectively x, y, and z-axis sets up reflecting mirror coordinate system.Pass through non-simultaneously Calculating the impact of the non-parallel angle of sunlight, wherein random ray relative is in incident beam key light for equally distributed probabilistic model The radial direction drift angle δ of axle_solWith circumferential bias angle theta_solAlso formula (4) can be pressed respectively calculate；Then consider sunlight entering on heat collector The impact of firing angle θ, you can obtain sunlight incident direction vector i under reflecting mirror coordinate system_m.

p_m=[nl (ξ₁-0.5) nw(ξ₂-0.5) f(y)]^t(3)

${\mathrm{\&delta;}}_{sol}={\sin }^{-1}\left(\sqrt{{\mathrm{\&xi;}}_3{\sin }^2\mathrm{\&delta;}}\right),{\mathrm{\&theta;}}_{sol}=2{\mathrm{\&pi;\&xi;}}_4---\left(4\right)$

In formula, f (y) is groove type heat collector reflecting mirror (referring to Fig. 2) section curved dies, preferably parabolic type；N is meter Calculate the heat collector number in unit；L and w is respectively the length and width of each heat collector reflecting mirror, m；δ is solar apparent diameter 1/2nd, rad；

6-3) and then, judge whether light is blocked by adjacent groove type heat collector.If not being blocked, following calculation light with Groove type heat collector reflecting mirror, glass tubing, the intersection point of endothermic tube.Meanwhile, reflection at each part for the light, refraction and absorption are judged Two-phonon process；

6-3-1) when light reaches mirror surface, judging whether to reflect by formula (5), if there is transmitting, leading to Cross formula (6) to calculate the reflective vector r of light_m.Wherein, mirror mirror actual normal vector n_mConsider reflecting mirror shape surface error Standard deviation sigma_mImpact to reflection process, n_mRadial direction δ with respect to preferable normal vector_rWith circumferential bias angle theta_rCalculated using formula (7).

0≤ξ₅＜ ρ_m·ρ_soil, reflect (5)

r_m=2 (i_m·n_m)n_m-i_m(6)

${\mathrm{\&delta;}}_r={\sin }^{-1}\left(\sqrt{{\mathrm{\&xi;}}_6{\sin }^2{\mathrm{\&sigma;}}_m}\right),{\mathrm{\&theta;}}_r=2{\mathrm{\&pi;\&xi;}}_7---\left(7\right)$

6-3-2) when light reaches glass tube exterior surface, to judge the optical effect mode of light by formula (8).If light Line is then counted absorbed energy by absorption and records its absorption position；If there is refraction, being calculated in glass using formula (9) and rolling over Directive amount re_o.Light can also be calculated in the refracting process of glass pipe internal surface and after being reflected using identical method Vectorial re_i.

0≤ξ₈＜ τ_g, refraction；τ_g≤ξ₈＜ 1- ρ_g, absorb；1-ρ_g≤ξ₈≤ 1, reflect (8)

${\mathrm{re}}_o=k_{1}i+k_{2}n,k_1=1/n_g,k_2=k_1{\mathrm{cos\&theta;}}_i-\sqrt{1-k_1^2{\sin }^2{\mathrm{\&theta;}}_i}---\left(9\right)$

θ in formula_iFor angle of incidence on air and glass tubing interface for the light, n is the surface normal at incidence point.

6-3-3) after light reaches heat absorption pipe surface, ray optics model of action is judged by formula (10), if light Absorbed, statistics energy absorption simultaneously records absorption position；If light is diffusely reflected, calculated on endothermic tube using blue Bei Tedinglv Diffuse-reflectance vector r_c.

0≤ξ₈＜ α₃, absorb；ξ₈≥α₃, diffuse-reflectance (10)

6-3-4) next proceed to calculate heat absorption tube outer surface to diffuse the intersection point of line and glass pipe internal surface, adopt simultaneously Judge its optical effect process with formula (8) and adopt step 6-3-1)～6-3-3) described in method continue to light calculate single Communication process in unit carries out calculating until light is absorbed or reflected and loses.Finally can be counted according to above-mentioned calculating and be managed Solar power q being absorbed with each calculating moment in glass tubing is thought on endothermic tube under state_3,i,q_45,i, and it is single to obtain calculating Unit perfect optics efficiency value η at this moment_opt,i, it is defined as q_3,iWith institute's energy in notch type reflecting mirror aperture area when calculating The ratio of the solar power of maximum receiving；

6-4) last, consider further due to sunlight in the angle of incidence of reflecting mirror plane of the opening caused by computing unit Final optical loss/income coefficient η_end, the glass tubing reflected light that caused due to non-perpendicular transmission on glass tubing for the sunlight Learning loss coefficient is incident angle modifier η_iam, heat collector tracking error coefficient η_track, other synthetic error coefficient η_generalRight The impact of computing unit optical efficiency, is calculated computing unit actual optical efficiency η at this moment using formula (11)_opt；With Shi Caiyong formula (12) can be calculated computing unit heat absorption pipe outer wall actual absorption solar power q₃, glass tubing actual absorption too Sun can power q₄₅；

η_opt=η_opt,i·η_end·η_iam·η_track·η_general(11)

q₃=q_3,i·η_end·η_iam·η_track·η_general,q₄₅=q_45,i·η_end·η_iam·η_track·η_general(12)

7) the photothermal deformation process in computing unit is calculated；

Set up its one-dimensional photothermal deformation computation model for computing unit thermal-collecting tube Parametric geometric model, using to spreading Heat, conduction heat transfer, radiant heat transfer computational methods are calculated, obtain this computing unit in whole year by when photothermal deformation effect Rate, working medium caloric receptivity and outlet temperature etc..

7-1) in the endothermic tube of computing unit, single-phase convection heat exchange power calculating formula is formula (13) and imports and exports preservation of energy Equation is formula (14).

q₁₂=2 π r₂nlh₁₂(t₂-t₁),h₁₂=nu₁₂λ₁/(2r₂),t₁=(t_out+t_in)/2 (13)

q₁₂=m_in(c_p,outt_out-c_p,int_in) (14)

In formula, m_inFor tube inlet working medium mass flow of absorbing heat, kg m^-1；t_in,t_outIt is respectively computing unit endothermic tube to enter Outlet Temperature of Working, k；t₁,t₂It is respectively and import and export working medium mean temperature and heat absorption inside pipe wall mean temperature, k；c_p,in,c_p,outPoint Do not import and export working medium specific heat capacity j (kg k) for computing unit endothermic tube^-1；r₂For the bore that absorbs heat, m.

According to different Bottomhole pressure Reynolds number re₁, Prandtl number pr₁Select with the draw ratio of endothermic tube in computing unit etc. Select heat convection correlation in different endothermic tubes.

Laminar convection Heat transfer corelation:

nu₁₂=4.3636 (15)

The formula scope of application is re₁<2300；

Dittus-boelter formula:

${\mathrm{nu}}_{12}=0.023{\mathrm{re}}_1^{0.8}{\mathrm{pr}}_1^c---\left(16\right)$

The formula scope of application is, c=0.4 during heating fluid, c=0.3, re during cooling fluid₁=10⁴～1.2 × 10⁵, pr₁=0.7～120, draw ratio nl/ (2r₂)≥60；L is the length of every endothermic tube, m；

Gnielinski formula:

${\mathrm{nu}}_{12}=\frac{(f/8)({\mathrm{re}}_1-1000){\mathrm{pr}}_1}{1+12.7\sqrt{f/8}({\mathrm{pr}}_1^{2/3}-1)}\&lsqb;1+{\left(\frac{2r_2}{nl}\right)}^{2/3}\&rsqb;\&centerdot;{\left(\frac{{\mathrm{pr}}_1}{{\mathrm{pr}}_2}\right)}^{0.01}---\left(17\right)$

The formula scope of application is pr₁/pr₂=0.05～20, re₁=2300～10⁶,pr₁=0.6～10⁵；

Resistance coefficient in gnielinski formula adopts filonenko formula to calculate:

F=(1.82lgre₁-1.64)^-2(18)

The formula scope of application is re₁=2300～10⁶, pr₁=0.6～10⁵；

7-2) the heat conduction power calculation between heat absorption pipe outer wall and inwall:

q₂₃=2 π λ₂₃nl(t₃-t₂)/ln(r₃/r₂) (19)

7-3) radiant heat transfer between heat absorption pipe outer wall and glass inside pipe wall calculates:

$q_{34}=2{\mathrm{\&pi;r}}_{3}nl\mathrm{\&sigma;}(t_3^4-t_4^4)/\&lsqb;\frac{1}{{\mathrm{\&epsiv;}}_3}+\frac{r_3}{r_4}(\frac{1}{{\mathrm{\&epsiv;}}_4}-1)\&rsqb;---\left(20\right)$

In formula, σ is black body radiation constant, w (m²·k⁴)^-1；

7-4) calculated by the heat flow of glass tubing surfaces externally and internally:

$q_4=\frac{2{\mathrm{\&pi;\&lambda;}}_{45}nl}{ln(r_5/r_4)}(t_4-t_5)+q_{45}(\frac{r_4^2}{r_5^2-r_4^2}-\frac{1}{2ln(r_5/r_4)})---\left(21\right)$

$q_5=\frac{2{\mathrm{\&pi;\&lambda;}}_{45}nl}{ln(r_5/r_4)}(t_4-t_5)+q_{45}(\frac{r_5^2}{r_5^2-r_4^2}-\frac{1}{2ln(r_5/r_4)})---\left(22\right)$

7-5) the heat convection between glass pipe outer wall and air, and the calculation of radiation heat transferring and surrounding between:

$q_{567}=2{\mathrm{\&pi;r}}_5{\mathrm{nlh}}_{56}(t_5-t_6)+2{\mathrm{\&pi;r}}_5{\mathrm{nl\&sigma;\&epsiv;}}_5(t_5^4-t_7^4),h_{56}={\mathrm{nu}}_{56}{\mathrm{\&lambda;}}_{56}/\left(2r_5\right)---\left(23\right)$

According to different Rayleigh numbers ra₅₆, Reynolds number re₅₆, Prandtl number pr₅₆Change Deng selecting the outer convection current of different glass tubings Hot correlation；

Calm free convection churchill-chu formula:

${\mathrm{nu}}_{56}=0.68+0.67{\mathrm{ra}}_{56}^{0.25}/{\&lsqb;1+{(0.492/{\mathrm{pr}}_{56})}^{9/16}\&rsqb;}^{4/9}---\left(24\right)$

The formula scope of application is ra₅₆＜ 10⁹,re₅₆≤1；

Eckert-drake formula:

${\mathrm{nu}}_{56}=(0.43+0.5{\mathrm{re}}_{56}^{0.5}){\mathrm{pr}}_{56}^{0.38}{\left(\frac{{\mathrm{pr}}_6}{{\mathrm{pr}}_5}\right)}^{0.25}---\left(25\right)$

The formula scope of application is re₅₆=1～10³；

Churchill-bernstein formula:

${\mathrm{nu}}_{56}=0.3+\frac{0.62{\mathrm{re}}_{56}^{0.5}{\mathrm{pr}}_{56}^{1/3}}{{\&lsqb;1+{(0.4/{\mathrm{pr}}_{56})}^{2/3}\&rsqb;}^{1/4}}{\&lsqb;1+{\left(\frac{{\mathrm{re}}_{56}}{282000}\right)}^{5/8}\&rsqb;}^{0.8}---\left(26\right)$

The formula scope of application is re₅₆=10³～10⁷,pe₅₆>0.2.

8) to the solar energy converging of all computing units of series connection and photothermal deformation in slot light collection solar energy heating loop The method that process is solved step by step；

Repeat step 6), step 7), solar energy converging and the photothermal deformation mistake to all computing units of series connection in loop Cheng Jinhang solves step by step, until being calculated the outlet parameter of last computing unit endothermic tube of loop.Will be calculated Circuit outlet Temperature of Working and circuit outlet design temperature contrast, if the two difference is within 0.1%, loop flow now m_inMeet design requirement；Otherwise then adjust m_inValue and calculated again, until circuit outlet temperature meet require till. The concrete method for solving being wherein directed to the middle computing unit in loop is as follows:

8-1) according to law of conservation of energy, establishment step 7) in each heat flow between equilibrium equation:

q₂₃=q₁₂,q₃₄=q₃-q₂₃,q₄=q₃₄,q₅=q₅₆₇(27)

8-2) pass through simultaneous equations (13)～(27), in known air temperature t₆, ambient temperature t₇, computing unit import work Matter temperature t_inWith flow m_inIn the case of, computing unit outlet Temperature of Working t can be obtained_out, wall temperature t inside and outside endothermic tube₂,t₃、 Wall temperature t inside and outside glass tubing₄,t₅, each heat flow value q₁₂,q₂₃,q₃₄,q₄,q₅,q₅₆₇.

8-3) the parameter transmission between each computing unit in loop

In the hot loop of a collection, comprise multiple computing units from circuit entrance to circuit outlet.Each is calculated single Unit, its sender property outlet parameter is the suction parameter of next computing unit.The suction parameter of initial unit is equal to loop and inhales The suction parameter of heat pipe, the outlet parameter of last computing unit is equal to the outlet parameter of whole loop endothermic tube.

9) by when calculate in whole year the single loop heat production power in each moment and by heat production power and this institute in calculating moment The time interval representing is multiplied, and then passes through and for the single loop quantity of heat production addition in each time interval to obtain the complete of single loop Year quantity of heat production q_l,design.

10) according to step 1) in heat collecting field whole year quantity of heat production design requirement and step 9) in the whole year heat production of single loop Amount calculates loop quantity n needed for resulting estimate collecting system to be designed_l,design=q_s,required/q_l,design.Simultaneously according to step 2) setting in determines the loop number of each subregion of heat collecting field.

11) it is directed to each of all subregions loop and adopt step 5) to step 9) methods described calculating each loop whole year Quantity of heat production, and obtain collecting system whole year quantity of heat production q by being added each loop whole year quantity of heat production_s,design.

12) judge whether result of calculation meets design requirement by formula (28), if designing the whole year of the collecting system obtaining Quantity of heat production q_s,designMeet design requirement then to terminate to calculate；If being unsatisfactory for requiring, loop number is adjusted to n '_l,designAfterwards Return to step 11) continue to calculate, until it reaches till requirement.

Table 1 slot light collection solar thermal collection system method for designing parameter list

Claims (8)

1. a kind of slot light collection solar thermal collection system method for designing is it is characterised in that comprise the following steps:

1) determine annual quantity of heat production design requirement q of slot light collection solar thermal collection system to be designed_s,required, specific geographic Location parameter and meteorological parameter information；Wherein, slot light collection solar thermal collection system to be designed presses north and south on the whole by multiple Trend is simultaneously made up of the thermal-arrest loop of the u shape arrangement of drift angle on east-west direction, is connected by some groove type heat collectors in each loop Constitute, each heat collector is mainly made up of slot type reflecting mirror and thermal-collecting tube and tracing control mechanism；

2) determine the basic geometrical structure parameter of slot light collection solar thermal collection system to be designed, set up the three-dimensional of collection hot loop Geometric model；

3) determine the hot physical property ginseng of slot light collection solar thermal collector each component optical parameter and thermal physical property parameter, heat-transfer working medium Number；

4) determine inlet flow rate initial setting m in slot light collection solar energy heating loop_inWith out temperature setting value；

5) computing unit division is carried out to slot light collection solar energy heating loop, that is, with individual by continuous n in slot type collection hot loop The structure of closely coupled groove type heat collector composition is computing unit, n >=1, and each computing unit after division is considered one Independent solar energy converging and photothermal deformation equipment；

6) solar energy converging process in computing unit is calculated: set up its optical mode for computing unit 3-D geometric model Type, carries out optical computing using Monte Carlo ray tracking method, obtain this computing unit in whole year by when optical efficiency, The thermal power absorbing in real time in heat absorption tube outer surface and glass tubing；

7) the photothermal deformation process in computing unit is calculated: set up for computing unit thermal-collecting tube Parametric geometric model Its one-dimensional photothermal deformation computation model, is calculated using convection heat transfer' heat-transfer by convection, conduction heat transfer, radiant heat transfer computational methods, and obtaining should Computing unit in whole year by when photo-thermal conversion efficiency, working medium caloric receptivity and outlet temperature；

8) repeat step 6) and step 7), the solar energy to all computing units of series connection in slot light collection solar energy heating loop Converge and solved step by step with photothermal deformation process, until being calculated the outlet of the endothermic tube of last computing unit of loop Parameter, calculated circuit outlet Temperature of Working and circuit outlet design temperature are contrasted, if the two difference 0.1% with Interior, then loop mass flow m now_inMeet design requirement；Otherwise then adjust m_inValue and calculated again, until return Till way outlet temperature meets requirement；

9) by when calculate in whole year the single loop heat production power in each moment and by representated by heat production power and this calculating moment Time interval be multiplied the single loop quantity of heat production obtaining in this time interval, then pass through single time in each time interval Road quantity of heat production is added the annual quantity of heat production q obtaining single loop_l,design；

10) according to step 1) in heat collecting field whole year quantity of heat production design requirement q_s,requiredWith step 9) in single loop annual Quantity of heat production result of calculation estimates thermal-arrest loop quantity n needed for heat collecting field to be designed_l,design=q_s,required/q_l,design；Then, root According to step 2) in setting determine the thermal-arrest loop quantity of each subregion of heat collecting field；

11) it is directed to each of all subregions of heat collecting field loop and adopt step 5) to step 9) calculate the whole year heat production of each loop Amount, and obtain collecting system whole year quantity of heat production q by being added each loop whole year quantity of heat production_s,design；

12) judge whether result of calculation meets design requirement by formula (1), if the annual quantity of heat production of the collecting system obtaining q_s,designMeet design requirement then to terminate；If being unsatisfactory for requiring, return to step 11 after the number of adjustment loop) continue to calculate, directly To meeting design requirement；

2. slot light collection solar thermal collection system method for designing according to claim 1 it is characterised in that: described step 1) Determine that geo-location parameter and meteorologic parameter include:

Heat collecting field local latitude to be designed, longitude and time zone data；Heat collecting field to be designed constant duration of local whole year is by seasonal epidemic pathogens Image data, described meteorological data include annual constant duration by when measurement obtain beam radia intensity, dry-bulb temperature, Wind speed, wind direction and atmospheric pressure.

3. slot light collection solar thermal collection system method for designing according to claim 1 it is characterised in that: described step 2) The basic geometrical structure parameter of slot light collection solar thermal collection system includes: the reflecting mirror Opening length l of single heat collector and width Outer radius r in degree w, glass tubing and endothermic tube effective length l, glass tubing₄,r₅, outer radius r in endothermic tube₂,r₃；Heat collecting field subregion Number and each subregion arranged thermal-arrest loop number account for the ratio of total loop number；The heat collector number of single collection hot loop, Spacing d on Working fluid flow direction for each heat collector_1ine；Spacing d between each row of heat collector_row；

Set up collection hot loop 3-D geometric model to include: set up the three of slot light collection solar energy heating loop using mathematic(al) representation The three-dimensional parameterized geometric model of dimension optical system, the expression formula of this Parametric geometric model includes the reflecting mirror post of computing unit Face equation, glass pipe outer wall face of cylinder equation, glass inside pipe wall face of cylinder equation and heat absorption pipe outer wall face of cylinder equation.

4. slot light collection solar thermal collection system method for designing according to claim 1 it is characterised in that: described step 3) In determination heat collector optical parametric include with the thermal physical property parameter of thermal physical property parameter, heat-transfer working medium:

Reflecting mirror, endothermic tube, the material of glass tubing, reflectance of reflector ρ_m, cleanliness factor ρ_soil, shape surface error standard deviation sigma_m, glass Pipe absorbance α_g, transmissivityτ_g, reflectivity ρ_gAnd refractive index θ_g, absorb heat pipe outer wall coating for selective absorption absorbance α₃, emissivity ε₃, endothermic tube heat conductivity λ₂₃, glass tubing heat conductivity λ₄₅, the heat conductivity λ of heat-transfer working medium₁With specific heat capacity c_p.

5. slot light collection solar thermal collection system method for designing according to claim 1 it is characterised in that: described step 6) In computing unit, solar energy converging process computational methods are as follows:

Formula (2) and (3) 6-1) are adopted to calculate heat collector respectively and follow the tracks of angle beta_cWith incidence angle θ on heat collector for the sunlight,

In formula, α, a are respectively local true solar time t_sWhen sun altitude and azimuth, work as t_s< during 12h, a is on the occasion of working as t_s> During 12h, a is negative value；α_c,a_cIt is respectively inclination angle and the azimuth of heat collecting field, North and South direction cloth is pressed in wherein each loop on the whole Put and drift angle, α when with respect to the horizontal plane upwarping when loop southern side can be had on east-west direction_cBe on the occasion of, otherwise α_cFor negative value, and The a when loop southern side deflection east_cBe on the occasion of, otherwise a_cFor negative value；

6-2) carry out communication process in computing unit for the solar radiation using Monte Carlo ray tracking method to calculate

Incident solar radiation is approximately the random light carrying identical energy in a large number；Light entering on computing unit reflecting mirror Penetrate position to be determined by equally distributed probabilistic model, that is, adopt formula (4) to calculate often and restraint light random site p on the mirror_m, Wherein with computing unit mirror center as initial point, mirror length, width and center vertical line direction are respectively x, y, and z-axis is set up Reflecting mirror coordinate system, calculates the impact of the non-parallel angle of sunlight simultaneously by the probabilistic model of non-uniform Distribution, wherein with Machine ray relative is in the radial direction drift angle δ of incident beam primary optical axis_solWith circumferential bias angle theta_solPress formula (5) respectively to calculate；Then consider The impact of incidence angle θ on heat collector for the sunlight, that is, obtain sunlight incident direction vector i under reflecting mirror coordinate system_m；

p_m=[nl (ξ₁-0.5) nw(ξ₂-0.5) f(y)]^t(4)

In formula, f (y) is groove type heat collector section type equation with parabolic form；N is the heat collector number in computing unit；L and w is respectively For the length and width of each heat collector reflecting mirror, m；δ is 1/2nd, rad of solar apparent diameter；

6-3) sunray and computing unit each component optical mechanism calculate

Judge whether light is blocked by adjacent groove type heat collector；If not being blocked, continue to calculate light and groove type heat collector reflection Mirror, glass tubing, the intersection point of endothermic tube, judge the two-phonon process of reflection at each part for the light, refraction and absorption meanwhile；

6-3-1) when light reaches mirror surface, judging whether to reflect by formula (6), if there is transmitting, passing through Formula (7) is calculating the reflective vector r of light_m；Wherein, mirror mirror actual normal vector n_mConsider reflecting mirror shape surface error mark Quasi- difference σ_mImpact to reflection process, n_mRadial direction δ with respect to preferable normal vector_rWith circumferential bias angle theta_rCalculated using formula (8)；

0≤ξ₅<ρ_m·ρ_soil, reflect (6)

r_m=2 (i_m·n_m)n_m-i_m(7)

ρ in formula_m,ρ_soilIt is respectively reflectance of reflector, cleanliness factor；

6-3-2) when light reaches glass tube exterior surface, to judge the optical effect mode of light by formula (9), if light quilt Absorb then to count absorbed energy and record it and absorb position；If there is refraction, calculated in glass using the light law of refraction The vectorial re of refraction_o；Vector in the refracting process of glass pipe internal surface and after being reflected for the light is calculated using identical method re_i；After light reaches heat absorption tube outer surface, ray optics model of action is judged by formula (10), if light is absorbed, Statistics energy absorption simultaneously records absorption position；If light is diffusely reflected, calculate the diffuse-reflectance on endothermic tube using blue Bei Tedinglv Vectorial r_c；

0≤ξ₈<τ_g, refraction；τ_g≤ξ₈<1-ρ_g, absorb；1-ρ_g≤ξ₈≤ 1, reflect (9)

0≤ξ₈<α₃, absorb；ξ₈≥α₃, diffuse-reflectance (10)

τ in formula_g,ρ_gIt is respectively glass tubing absorbance, reflectance；α₃For the pipe outer wall coating for selective absorption absorbance that absorbs heat；

6-3-3) next proceed to calculate heat absorption tube outer surface to diffuse the intersection point of line and glass pipe internal surface, adopt formula simultaneously (9) judge its optical effect process and adopt step 6-3-1)～6-3-2) and described in method continue to light in computing unit Communication process carry out calculating until light is absorbed or reflected and loses；Preferable shape is obtained according to the final statistics of above-mentioned calculating Solar power q being absorbed with each calculating moment in glass tubing on endothermic tube under state_3,i,q_45,i, and obtain computing unit and exist The perfect optics efficiency value η in this moment_opt,i, it is defined as q_3,iCan connect in notch type reflecting mirror aperture area with during this calculating The ratio of the maximum solar power received；

6-4) last, consider further due to sunlight in the angle of incidence of reflecting mirror plane of the opening caused by computing unit end Optical loss/income coefficient η_end, the glass tubing reflection optics that caused due to non-perpendicular transmission on glass tubing for the sunlight damaged Losing coefficient is incident angle modifier η_iam, heat collector tracking error coefficient η_track, other synthetic error coefficient η_generalTo calculating The impact of unit optical efficiency, is calculated computing unit actual optical efficiency η at this moment using formula (11)_opt；Adopt simultaneously Can be calculated computing unit heat absorption pipe outer wall actual absorption solar power q with formula (12)₃, glass tubing actual absorption solar energy Power q₄₅；

η_opt=η_opt,i·η_end·η_iam·η_track·η_general(11)

q₃=q_3,i·η_end·η_iam·η_track·η_general,q₄₅=q_45,i·η_end·η_iam·η_track·η_general(12)

In calculating formula, each ξ all represents one and obeys equally distributed random number in (0,1) is interval, and all randoms number Separate；

In the calculation, the numeral in physical quantity subscript represents each structure respectively and corresponds to parameter, wherein 1- heat absorption intraductal working medium, 2- heat absorption Inside pipe wall, 3- heat absorption pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding air, 7- surrounding, meanwhile, physical property The subscript of parameter and dust suppression by spraying represents the qualitative temperature of its structure being adopted, ε₃Represent heat absorption pipe outer wall with t₃For qualitative The emissivity of temperature, λ₄₅Represent glass tubing with internal and external walls mean temperature t₄₅=(t₄+t₅)/2 are the heat conductivity of qualitative temperature.

6. slot light collection solar thermal collection system method for designing according to claim 1 it is characterised in that: described step 7) Computing unit in photothermal deformation process computational methods as follows:

7-1) in the endothermic tube of computing unit, single-phase convection heat exchange power calculating formula and import and export energy conservation equation formula are respectively Formula (13) and formula (14)；

q₁₂=2 π r₂nlh₁₂(t₂-t₁),h₁₂=nu₁₂λ₁/(2r₂),t₁=(t_out+t_in)/2 (13)

q₁₂=m_in(c_p,outt_out-c_p,int_in) (14)

In formula, m_inFor tube inlet working medium mass flow of absorbing heat, kg m^-1；t_in,t_outIt is respectively computing unit endothermic tube to import and export Temperature of Working, k；t₁,t₂It is respectively and import and export working medium mean temperature and heat absorption inside pipe wall mean temperature, k；c_p,in,c_p,outIt is respectively Computing unit endothermic tube imports and exports working medium specific heat capacity, j (kg k)^-1；r₂For the bore that absorbs heat, m；

According to different heat absorption Bottomhole pressure Reynolds number re₁, Prandtl number pr₁Select with the draw ratio of endothermic tube in computing unit Heat convection correlation in different endothermic tubes；

Laminar convection Heat transfer corelation:

nu₁₂=4.3636 (15)

The formula scope of application is re₁<2300；

Dittus-boelter formula:

The formula scope of application is, c=0.4 during heating fluid, c=0.3, re during cooling fluid₁=10⁴～1.2 × 10⁵, pr₁= 0.7～120, draw ratio nl/ (2r₂)≥60；L is the length of every endothermic tube, m；

Gnielinski formula:

The formula scope of application is pr₁/pr₂=0.05～20, re₁=2300～10⁶,pr₁=0.6～10⁵；

Resistance coefficient in gnielinski formula adopts filonenko formula to calculate:

F=(1.82lgre₁-1.64)^-2(18)

The formula scope of application is re₁=2300～10⁶, pr₁=0.6～10⁵；

7-2) the heat conduction power calculation between heat absorption pipe outer wall and inwall

q₂₃=2 π λ₂₃nl(t₃-t₂)/ln(r₃/r₂) (19)

7-3) radiant heat transfer between heat absorption pipe outer wall and glass inside pipe wall calculates

In formula, σ is black body radiation constant, w (m²·k⁴)^-1；

7-4) calculated by the heat flow of glass tubing surfaces externally and internally

7-5) the heat convection between glass pipe outer wall and air, and the calculation of radiation heat transferring and surrounding between

According to different Rayleigh numbers ra₅₆, Reynolds number re₅₆, Prandtl number pr₅₆Close Deng selecting the outer heat convection of different glass tubings Connection formula；

Calm free convection churchill-chu formula:

The formula scope of application is ra₅₆<10⁹,re₅₆≤1；

Eckert-drake formula:

The formula scope of application is re₅₆=1～10³；

Churchill-bernstein formula:

The formula scope of application is re₅₆=10³～10⁷,pe₅₆>0.2.

7. slot light collection solar thermal collection system method for designing according to claim 1 it is characterised in that: described step 8) In the solar energy converging of all computing units of series connection in slot light collection solar energy heating loop is carried out with photothermal deformation process The method solving step by step is as follows:

8-1) according to law of conservation of energy, establishment step 7) in each heat flow between equilibrium equation:

q₂₃=q₁₂,q₃₄=q₃-q₂₃,q₄=q₃₄,q₅=q₅₆₇(27)

8-2) pass through simultaneous equations (13)～(27), in known air temperature t₆, ambient temperature t₇, computing unit import working medium temperature Degree t_inWith flow m_inIn the case of, obtain computing unit outlet Temperature of Working t_out, wall temperature t inside and outside endothermic tube₂,t₃, in glass tubing Outer wall temperature t₄,t₅, each heat flow value q₁₂,q₂₃,q₃₄,q₄,q₅,q₅₆₇；

8-3) the parameter transmission between each computing unit in loop

In the hot loop of a collection, comprise multiple computing units from circuit entrance to circuit outlet, for each computing unit, its Sender property outlet parameter is the suction parameter of next computing unit, and the suction parameter of initial unit is equal to entering of loop endothermic tube Mouth parameter, the outlet parameter of last computing unit is equal to the outlet parameter of whole loop endothermic tube.

8. slot light collection solar thermal collection system method for designing according to claim 1 it is characterised in that: described step 12) the adjustment feeder number purpose method such as formula (28) in:

Loop number after wherein adjusting is n '_l,design.