CN106369838B - A kind of slot light collection solar thermal collection system design method - Google Patents
A kind of slot light collection solar thermal collection system design method Download PDFInfo
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Abstract
A kind of slot light collection solar thermal collection system design method first, according to local meteorologic parameter, collecting system fabricating yard physical dimension and system applying working condition, determines the basic geometry of collecting system and establishes the Parametric geometric model of single collection hot loop；Then, circuit three-dimensional optical computation model is established using Monte Carlo ray tracking method and carries out optical computing, obtain annual each moment circuit by when integrated optical performance；Then, using the one-dimensional photothermal conversion computation model of circuit thermal-collecting tube, calculate single collection hot loop it is annual by when integrate heat production performance and gross annual output heat；Then, according to the design requirement of system gross annual output heat, Preliminary design collecting system total loop number；Finally, calculated by assessing the annual quantity of heat production of Preliminary design collecting system and carrying out the optimization of feeder number mesh, be finally completed the design of collecting system；This method can quickly and effectively carry out slot light collection solar thermal collection system structure and be designed with comprehensive light thermal property.
Description
Technical field
The invention belongs to light-focusing type solars to utilize technical field, and in particular to a kind of slot light collection solar energy heating system
System design method.
Background technology
The environmental problem and society that the increasingly depleted of fossil energy, using energy source are brought are 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 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 obtained extensively.In solar utilization technique, slot light collection heliotechnics is a kind of has a extensive future too
Positive energy heat utilization technology.Wherein, slot type collecting system quick, efficient, High Precision Automatic design and assessment be one and important grind
Study carefully problem.
Light-concentrating solar heat-collection system mainly can simultaneously be had centainly partially by south-north direction on east-west direction on the whole by multiple
The thermal-arrest circuit composition of the U-shaped arrangement at angle, each circuit is in series by several groove type heat collectors, and each heat collector is mainly by slot
Formula speculum and thermal-collecting tube (main to include external glass tube and internal metal heat absorption tube) and corresponding tracing control machine
Structure forms.The solar energy converging complicated as one and converting system, the design of slot type collecting system are involved in complicated reality
Border geography and the complicated solar energy converging collection process in meteorologic 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.Therefore need research one kind that can quickly and effectively carry out
Slot light collection solar thermal collection system design and performance assessment, improve development efficiency, reduce development cost it is reasonable, science from
Dynamicization design method.
The content of the invention
That slot light collection solar thermal collection system can be efficiently accomplished is three-dimensional parameterized several it is an object of the invention to provide a kind of
What model, optical computing model and Calculation of Heat Transfer modelling quickly and effectively carries out slot light collection solar thermal collection system knot
Structure is designed with comprehensive light thermal property, solves the problems, such as the slot light collection solar thermal collection system design method of system Automated Design.
In order to achieve the above objectives, the technical solution adopted in the present invention is as follows：
1) the annual quantity of heat production design requirement Q of slot light collection solar thermal collection system to be designed is determineds,required, it is specific
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 of on east-west direction the thermal-arrest circuit of the U-shaped arrangement of drift angle, and each circuit is by several groove type heat collectors
In series, each heat collector is mainly made of slot type speculum 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, establish collection hot loop
3-D geometric model；
3) each component optical parameter of slot light collection solar thermal collector and thermal physical property parameter, the hot physical property of heat-transfer working medium are determined
Parameter；
4) the inlet flow rate initial setting m in slot light collection solar energy heating circuit is determinedinWith out temperature setting value；
5) to slot light collection solar energy heating circuit carry out computing unit division, i.e., in slot type collection hot loop by continuous
The structure of groove type heat collectors composition closely coupled n is computing unit, n >=1, and each computing unit after division is considered as one
A independent solar energy converging and photothermal conversion equipment；
6) solar energy converging process in computing unit is calculated：Its light is established for computing unit 3-D geometric model
Learn model, using Monte Carlo ray tracking method carry out optical computing, obtain the computing unit in whole year by when optics
The thermal power absorbed in real time in efficiency, heat absorption tube outer surface and glass tube；
7) the photothermal conversion process in computing unit is calculated：For computing unit thermal-collecting tube Parametric geometric model
Its one-dimensional photothermal conversion computation model is established, is calculated, obtained using convection current heat transfer, conduction heat transfer, radiant heat transfer computational methods
Obtain the computing unit in whole year by when photothermal conversion efficiency, working medium caloric receptivity and outlet temperature；
8) step 6) and step 7) are repeated, to all computing units for connecting in slot light collection solar energy heating circuit too
Sun can be converged to be solved step by step with photothermal conversion process, until the endothermic tube of the last one computing unit of circuit is calculated
Outlet parameter compares the circuit outlet Temperature of Working being calculated and circuit outlet design temperature, if the two difference is 0.1%
Within, then loop mass flow m at this timeinMeet design requirement；It is on the contrary then adjust minValue and calculated again, until
Until circuit outlet temperature is met the requirements；
9) by when calculate it is annual in each moment single circuit heat production power and by heat production power and the calculating moment institute
The time interval of representative is multiplied to obtain the single circuit quantity of heat production in the time interval, then by by the list in each time interval
A circuit quantity of heat production is added to obtain the annual quantity of heat production Q in single circuitl,design；
10) according to the heat collecting field whole year quantity of heat production design requirement Q in step 1)s,requiredWith the single circuit in step 9)
Annual quantity of heat production result of calculation estimates thermal-arrest circuit quantity N needed for heat collecting field to be designedl,design=Qs,required/Ql,design；It connects
It, the thermal-arrest circuit quantity of each subregion of heat collecting field is determined according to the setting in step 2)；
11) the annual production in each circuit is calculated using step 5) to step 9) for each circuit in all subregions of heat collecting field
Heat, and pass through and be added each circuit whole year quantity of heat production to obtain collecting system whole year quantity of heat production Qs,design；
12) judge whether result of calculation meets design requirement by formula (1), if the annual quantity of heat production of obtained collecting system
Qs,designMeet design requirement then to terminate；If being unsatisfactory for requiring, return to step 11 after the number of circuit is adjusted) continue to calculate, directly
Until design requirement is met；
The step 1) determines that geo-location parameter and meteorologic parameter include：
Heat collecting field local latitude to be designed, longitude and time zone data；The local annual constant duration of heat collecting field to be designed by
When meteorological data, the meteorological data include annual constant duration by when measurement obtain beam radia intensity, dry bulb
Temperature, wind speed, wind direction and atmospheric pressure.
The basic geometrical structure parameter of step 2) the slot light collection solar thermal collection system includes：Single heat collector it is anti-
Penetrate mirror Opening length L and width W, outer radius R in glass tube and endothermic tube effective length l, glass tube4,R5, endothermic tube inside and outside half
Footpath R2,R3；Heat collecting field number of partitions and each subregion arrange that thermal-arrest circuit number accounts for the ratio of total loop number；Single thermal-arrest
Spacing d of the heat collector number, each heat collector in circuit on Working fluid flow direction1ine；Spacing d between each row of heat collectorrow；
Establishing collection hot loop 3-D geometric model includes：Slot light collection solar energy heating circuit is established using mathematic(al) representation
Three-dimensional optical system three-dimensional parameterized geometrical model, the expression formula of the Parametric geometric model includes the reflection of computing unit
Mirror cylindrical equation, glass pipe outer wall cylindrical surface equation, glass inside pipe wall cylindrical surface equation and heat absorption pipe outer wall cylindrical surface equation.
Definite heat collector optical parameter and thermal physical property parameter, the thermal physical property parameter bag of heat-transfer working medium in the step 3)
It includes：
Speculum, endothermic tube, the material of glass tube, reflectance of reflector ρm, cleanliness factor ρsoil, shape surface error standard deviation sigmam,
Glass tube absorptivity αg, transmissivityτg, reflectivity ρgAnd refractive index θg, heat absorption pipe outer wall coating for selective absorption absorptivity α3, hair
Penetrate rate ε3, endothermic tube thermal conductivity factor λ23, glass tube thermal conductivity factor λ45, the thermal conductivity factor λ of heat-transfer working medium1With specific heat capacity cp。
Solar energy converging process computational methods are as follows in the step 6) computing unit：
6-1) heat collector trail angle β is calculated respectively using formula (2) and (3)cWith incidence angle θ of the sunlight on heat collector,
In formula, α, A are respectively local true solar time tsWhen sun altitude and azimuth, work as ts<A is positive value during 12h,
Work as ts>A is negative value during 12h；αc,AcThe respectively inclination angle and azimuth of heat collecting field, wherein each circuit is on the whole by the South and the North
To arranging and can have drift angle on east-west direction, the α when circuit southern side with respect to the horizontal plane upwarpscFor positive value, α on the contrarycIt is negative
Value, and the A when circuit southern side deviation eastcFor positive value, A on the contrarycFor negative value；
6-2) communication process of the solar radiation in computing unit is carried out using Monte Carlo ray tracking method to calculate
It is approximately a large amount of random light for carrying identical energy incident solar radiation；Light is on computing unit speculum
Incoming position determined by equally distributed probabilistic model, i.e., the random order per beam light on the mirror is calculated using formula (4)
Put Pm, wherein using computing unit mirror center as origin, mirror length, width and center vertical line direction are respectively X, Y, Z
Axis establishes speculum coordinate system, while the influence of the non-parallel angle of sunlight is calculated by the probabilistic model of non-uniform Distribution,
Wherein random light compared with incident beam primary optical axis radial direction drift angle δsolWith circumferential bias angle thetasolIt is calculated respectively by formula (5)；It connects
It and considers the influence of incidence angle θ of the sunlight on heat collector to get vectorial to sunlight incident direction under speculum coordinate system
Im；
Pm=[nL (ξ1-0.5) nW(ξ2-0.5) f(y)]T (4)
F (y) is groove type heat collector section type equation with parabolic form in formula；N is the heat collector number in computing unit；L and W
The length and width of respectively each heat collector speculum, m；δ be solar apparent diameter half, rad；
6-3) sunray is calculated with each component optical mechanism of computing unit
Judge whether light is blocked by adjacent groove type heat collector；Continue to calculate light and groove type heat collector if not being blocked
Speculum, glass tube, the intersection point of endothermic tube, meanwhile, judge the optics mistake of reflection, refraction and absorption of the light at each component
Journey；
6-3-1) when light reaches mirror surface, by formula (6) to determine whether reflecting, if occurring to emit
The reflective vector R of light is calculated by formula (7)m；Wherein, the actual normal vector N of mirror mirrormConsider speculum shape face mistake
Poor standard deviation sigmamInfluence to reflection process, NmCompared with the radial direction δ of preferable normal vectorRWith circumferential bias angle thetaRIt is counted using formula (8)
It calculates；
0≤ξ5＜ ρm·ρsoil, reflect (6)
Rm=2 (Im·Nm)Nm-Im (7)
ρ in formulam,ρsoilRespectively reflectance of reflector, cleanliness factor；
6-3-2) when light reaches glass tube exterior surface, the optical effect mode of light is judged by formula (9), if light
Line, which is then counted absorbed energy by absorption and records its, absorbs position；Glass is calculated using the light law of refraction if generation reflects
Vector Re is reflected in glasso；After calculating light using identical method in the refracting process of glass pipe internal surface and reflected
Vectorial Rei；After light reaches heat absorption tube outer surface, the ray optics mode of action is judged by formula (10), if light is inhaled
Receipts, which then count to absorb energy and record, absorbs position；Overflowing on endothermic tube is calculated using orchid Bei Tedinglv if light is diffusely reflected
Reflective vector Rc；
0≤ξ8＜ τg, refraction；τg≤ξ8＜ 1- ρg, absorb；1-ρg≤ξ8≤ 1, it reflects (9)
0≤ξ8＜ α3, absorb；ξ8≥α3, diffusing reflection (10)
τ in formulag,ρgRespectively glass tube transmissivity, reflectivity；α3For pipe outer wall coating for selective absorption absorptivity of absorbing heat；
It 6-3-3) next proceeds 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 use step 6-3-1)~6-3-2) described in method continue to light calculate it is single
Communication process in member calculate until light is absorbed or reflected and loses；According to above-mentioned calculating, finally statistics obtains ideal
The solar power Q that the moment absorbed each is calculated under state on endothermic tube and in glass tube3,i,Q45,i, and obtain computing unit
Perfect optics efficiency value η at this momentopt,i, it is defined as Q3,iWith institute's energy in notch type speculum opening area during the calculating
The ratio of the maximum solar power of reception；
6-4) finally, the computing unit caused by incidence angle of the sunlight in speculum plane of the opening is further considered
Final optical loss/income coefficient ηend, due to non-perpendicular transmission of the sunlight on glass tube and caused by glass tube reflected light
Learn loss coefficient, that is, incident angle modifier ηIAM, heat collector tracking error coefficient ηtrack, other composition error coefficients ηgeneralIt is right
The actual optical efficiency η of computing unit at this moment is calculated using formula (11) in the influence of computing unit optical efficiencyopt；Together
Shi Caiyong formulas (12) can be calculated computing unit heat absorption pipe outer wall actual absorption solar power Q3, glass tube actual absorption too
Positive energy power Q45；
ηopt=ηopt,i·ηend·ηIAM·ηtrack·ηgeneral (11)
Q3=Q3,i·ηend·ηIAM·ηtrack·ηgeneral,Q45=Q45,i·ηend·ηIAM·ηtrack·ηgeneral (12)
In calculating formula, each ξ represents one and obeys equally distributed random number in (0,1) section, and it is all with
Machine number is mutual indepedent；
In the calculation, the number in physical quantity subscript represents each structure and corresponds to parameter respectively, wherein 1- absorb heat intraductal working medium,
2- heat absorptions inside pipe wall, 3- heat absorptions pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding airs, 7- ambient enviroments, together
When, the subscript of physical parameter and dust suppression by spraying represents the qualitative temperature of its used structure, ε3Represent heat absorption pipe outer wall with T3
Emissivity, λ for qualitative temperature45Represent glass tube with internal and external walls mean temperature T45=(T4+T5It is led for qualitative temperature)/2
Hot coefficient.
Photothermal conversion process computational methods in the computing unit of the step 7) are as follows：
7-1) single-phase convection heat exchange power calculating formula and inlet and outlet energy conservation equation formula point in the endothermic tube of computing unit
It Wei not formula (13) and formula (14)；
q12=2 π R2nlh12(T2-T1),h12=Nu12λ1/(2R2),T1=(Tout+Tin)/2 (13)
q12=min(cp,outTout-cp,inTin) (14)
In formula, minFor tube inlet working medium mass flow of absorbing heat, kgm-1；Tin,ToutRespectively computing unit endothermic tube into
Export Temperature of Working, K；T1,T2Respectively import and export working medium mean temperature and heat absorption inside pipe wall mean temperature, K；cp,in,cp,outPoint
Not Wei computing unit endothermic tube import and export working medium specific heat capacity, J (kgK)-1；R2For the bore that absorbs heat, m；
According to different heat absorption Bottomhole pressure reynolds number Res1, Prandtl number Pr1With the draw ratio of 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：
The formula scope of application is, c=0.4 when 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 is calculated using Filonenko formula：
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 absorbed heat between pipe outer wall and inner wall
q23=2 π λ23nl(T3-T2)/ln(R3/R2) (19)
7-3) radiant heat transfer to absorb heat between pipe outer wall and glass inside pipe wall calculates
In formula σ be black body radiation constant, W (m2·K4)-1；
7-4) calculated by the heat flow of glass tube surfaces externally and internally
7-5) heat convection between glass pipe outer wall and air and the calculation of radiation heat transferring between ambient enviroment
According to different Rayleigh number Ra56, reynolds number Re56, Prandtl number Pr56It is changed Deng the outer convection current of different glass tubes is selected
Hot correlation；
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。
Solar energy converging in the step 8) to all computing units connected in slot light collection solar energy heating circuit
The method solved step by step with photothermal conversion process 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) by simultaneous equations (13)~(27), in known air temperature T6, environment temperature T7, computing unit import work
Matter temperature TinWith flow minIn the case of, computing unit outlet Temperature of Working T is obtainedout, 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) parameter in circuit between each computing unit is transferred
In one collects hot loop, comprising multiple computing units from circuit entrance to circuit outlet, list is calculated for each
Member, sender property outlet parameter are the suction parameter of next computing unit, and the suction parameter of initial unit is absorbed heat equal to circuit
The suction parameter of pipe, the outlet parameter of the last one computing unit are equal to the outlet parameter of entire circuit endothermic tube；
Adjustment feeder number purpose method such as formula (28) in the step 12)：
Circuit number after wherein adjusting is N 'l,design。
Table 1 gives the list of used parameter in the slot light collection solar thermal collection system design method.Wherein, physics
Number in amount subscript represents parameter corresponding to each structure of heat collector, i.e. 1- heat absorptions intraductal working medium, 2- heat absorptions inside pipe wall, 3- respectively
Absorb heat pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding airs, such as 7- ambient enviroments, T3It is put down for heat absorption pipe outer wall
Equal temperature.Meanwhile the subscript of physical parameter and dust suppression by spraying represents that it uses the qualitative temperature of structure, such as ε3Represent heat absorption
Pipe outer wall is with T3Emissivity, λ for qualitative temperature45Represent glass tube with internal and external walls mean temperature T45=(T4+T5)/2 are fixed
The thermal conductivity factor of warm-natured degree.
The present invention is compared to traditional design method advantage：
(1) the present invention provides a kind of multiple subjects such as meteorology, geometric optics, hydrodynamics and thermal conduction study that combine
The whole annual comprehensive solar collecting performance assessment of slot light collection solar thermal collection system and automatic design method.
(2) design method of the present invention has extremely strong versatility, suitable for global anywhere, the heat collecting field in various orientation
Arrangement, various types of slot light collection solar thermal collectors.
(3) design method computational accuracy of the present invention and computational efficiency height, intelligent and high degree of automation, can make designer
Member quickly and efficiently completes slot light collection solar energy system geometrical model, optical computing model and Calculation of Heat Transfer modelling, and
The assessment and calculating of system whole year performance are efficiently and rapidly completed based on this, so as to fulfill the automatic of slot light collection solar energy system
Design.This method has important directive significance and engineer application valency for the design and optimization of slot light collection solar energy system
Value.
Table 1 is slot light collection solar thermal collection system design method parameter list
Description of the drawings
Fig. 1 is slot light collection solar thermal collection system structure diagram.
Fig. 2 is groove type heat collector structure diagram.
Reference numeral：1st, heat-transfer working medium, 2, heat absorption inside pipe wall, 3, heat absorption pipe outer wall, 4, glass inside pipe wall, 5, outside glass tube
Wall, 8, speculum, 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 design method 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；
Heat collecting field whole year quantity of heat production design load Q is determined according to design requirements,required.It inputs heat collecting field to be designed and works as ground weft
Degree, longitude, time zone data.Input the local annual constant duration of heat collecting field to be designed by when meteorological data；The meteorological data
It is 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, establish
Loop parameter geometrical model；
The geometric parameter of each heat collector (referring to Fig. 2) is determined according to the type of groove type heat collector, including speculum opening
Outer radius R in length L and width W, glass tube and endothermic tube effective length l, glass tube4,R5, outer radius R in endothermic tube2,R3；
Arrange that orientation and actual place physical dimension determine that heat collecting field number of partitions and each subregion arrange collection according to slot type Jing Chang
Hot loop number accounts for the ratio of total loop number；The geometry of definite collection hot loop, i.e., the heat collector number in definite each circuit,
Spacing d of each heat collector on Working fluid flow direction1ine；Finally, set according to heat collector geometric parameter and safe operation requirement
Spacing parameter d between each row of heat collectorrow；Slot light collection solar energy heating circuit optics is finally established using mathematic(al) representation
The three-dimensional parameterized geometrical model of system, the expression formula of the Parametric geometric model mainly include the speculum cylinder of computing unit
Equation, glass pipe outer wall cylindrical surface equation, glass inside pipe wall cylindrical surface equation, heat absorption pipe outer wall cylindrical surface equation.In the calculation,
Number in physical quantity subscript represents each structure and corresponds to parameter respectively, and wherein 1- heat absorptions intraductal working medium, 2- heat absorptions inside pipe wall, 3- inhale
Heat pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding airs, 7- ambient enviroments.
3) slot light collection solar thermal collector optical parameter and thermal physical property parameter, the thermal physical property parameter of heat-transfer working medium are determined；
Determine the speculum, endothermic tube, the material of glass tube of groove type heat collector, reflectance of reflector ρm, cleanliness factor ρsoil、
Shape surface error standard deviation sigmam, glass tube absorptivity, transmissivity, reflectivity and refractive index αg,τg,ρg,θg, heat absorption pipe outer wall selectivity
Absorber coatings absorptivity α3, emissivity ε3, endothermic tube thermal conductivity factor λ23, glass tube thermal conductivity factor λ45, the heat conduction system of heat-transfer working medium
Number λ1With specific heat capacity cp.Wherein, the subscript of physical parameter represents the qualitative temperature of its used component, such as ε3Represent endothermic tube
Outer wall is with T3Emissivity, λ for qualitative temperature45Represent glass tube with internal and external walls mean temperature T45=(T4+T5)/2 are qualitative
The thermal conductivity factor of temperature.The ginseng of the three-dimensional geometrical structure of the three-dimensional optical system of slot type computing unit is established using mathematic(al) representation
Numberization model, the expression formula of the Parametric geometric model mainly include speculum cylindrical equation, the glass pipe outer wall of computing unit
Cylindrical surface equation, glass inside pipe wall cylindrical surface equation, heat absorption pipe outer wall cylindrical surface equation.
4) light-concentrating solar heat-collection circuit operating parameter is determined；
According to the actual use operating mode of slot type heat collecting field and groove type heat collector type, loop length etc., collection hot loop is determined
Inlet flow rate initial setting min, out temperature setting value.
5) computing unit division is carried out to light-concentrating solar heat-collection circuit；
Hot loop is integrated as computing object using slot type, to be made of in circuit continuous n closely coupled groove type heat collectors
Structure for 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；
Its three-dimensional optical model is established using Monte Carlo ray tracking method for computing unit 3-D geometric model, and
Optical computing is carried out, obtains the thermal power absorbed in real time in the optical efficiency, heat absorption tube outer surface and glass tube of the computing unit.
In calculating, each ξ represents one and equally distributed random number is obeyed in (0,1) section, and all random numbers are mutually only
It is vertical.
6-1) first, heat collector trail angle β is calculated using following formulacWith incidence angle θ of the sunlight on heat collector：
In formula, α, A are respectively local true solar time tsWhen sun altitude and azimuth, work as ts<A is positive value during 12h,
Work as ts>A is negative value during 12h；αc,AcThe respectively inclination angle of heat collecting field and azimuth (referring to Fig. 1), wherein each circuit is whole
On arranged by North and South direction and can have certain drift angle on east-west direction, therefore the α when circuit southern side with respect to the horizontal plane upwarpsc
For positive value, α on the contrarycFor negative value, and the A when east is inclined in circuit southern sidecFor positive value, A on the contrarycFor negative value.
6-2) then, carry out communication process of the solar radiation in computing unit to calculate, be approximately incident solar radiation
A large amount of random light for carrying identical energy；Incoming position of the light on computing unit speculum is by equally distributed probability mould
Type determines, i.e., the random site P per beam light on the mirror is calculated using formula (3)m, wherein with computing unit mirror center
For origin, mirror length, width and center vertical line direction are respectively X, Y, and Z axis establishes speculum coordinate system.Simultaneously by non-
Equally distributed probabilistic model calculates the influence of the non-parallel angle of sunlight, wherein random light is compared with incident beam key light
The radial direction drift angle δ of axissolWith circumferential bias angle thetasolAlso formula (4) calculating can be pressed respectively；Then sunlight entering on heat collector is considered
The influence of firing angle θ, you can obtain sunlight incident direction vector I under speculum coordinate systemm。
Pm=[nL (ξ1-0.5) nW(ξ2-0.5) f(y)]T (3)
F (y) is groove type heat collector speculum (referring to Fig. 2) section curved dies in formula, is 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 speculum, m；δ is solar apparent diameter
Half, rad；
6-3) then, judge whether light is blocked by adjacent groove type heat collector.Tracked if not being blocked calculate light with
Groove type heat collector speculum, glass tube, the intersection point of endothermic tube.Meanwhile judge reflection, refraction and absorption of the light at each component
Two-phonon process；
6-3-1) when light reaches mirror surface, by formula (5) to determine whether reflecting, if occurring to emit
The reflective vector R of light is calculated by formula (6)m.Wherein, the actual normal vector N of mirror mirrormConsider speculum shape face mistake
Poor standard deviation sigmamInfluence to reflection process, NmCompared with the radial direction δ of preferable normal vectorRWith circumferential bias angle thetaRIt is counted using formula (7)
It calculates.
0≤ξ5＜ ρm·ρsoil, reflect (5)
Rm=2 (Im·Nm)Nm-Im (6)
6-3-2) when light reaches glass tube exterior surface, the optical effect mode of light is judged by formula (8).If light
Line, which is then counted absorbed energy by absorption and records its, absorbs position；It is calculated in glass and rolled over using formula (9) if generation reflects
Directive amount Reo.After can also calculating light using identical method in the refracting process of glass pipe internal surface and reflected
Vectorial Rei。
0≤ξ8＜ τg, refraction；τg≤ξ8＜ 1- ρg, absorb；1-ρg≤ξ8≤ 1, it reflects (8)
θ in formulaiFor incidence angle of the light on air and glass tube interface, N is the surface normal at incidence point.
6-3-3) after light reaches heat absorption pipe surface, the ray optics mode of action is judged by formula (10), if light
It is absorbed, count absorption energy and records absorption position；It is calculated if light is diffusely reflected using orchid Bei Tedinglv on endothermic tube
Diffusing reflection vector Rc。
0≤ξ8＜ α3, absorb；ξ8≥α3, diffusing reflection (10)
It 6-3-4) next proceeds 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 use step 6-3-1)~6-3-3) described in method continue to light calculate it is single
Communication process in member calculate until light is absorbed or reflected and loses.It can finally be counted and be managed according to above-mentioned calculating
Think under state each to calculate the solar power Q that the moment absorbed on endothermic tube and in glass tube3,i,Q45,i, and it is single to obtain calculating
The perfect optics efficiency value η of member at this momentopt,i, it is defined as Q3,iInstitute's energy in notch type speculum opening area during with calculating
The ratio of the maximum solar power of reception；
6-4) finally, the computing unit caused by incidence angle of the sunlight in speculum plane of the opening is further considered
Final optical loss/income coefficient ηend, due to non-perpendicular transmission of the sunlight on glass tube and caused by glass tube reflected light
Learn loss coefficient, that is, incident angle modifier ηIAM, heat collector tracking error coefficient ηtrack, other composition error coefficients ηgeneralIt is right
The actual optical efficiency η of computing unit at this moment is calculated using formula (11) in the influence of computing unit optical efficiencyopt；Together
Shi Caiyong formulas (12) can be calculated computing unit heat absorption pipe outer wall actual absorption solar power Q3, glass tube actual absorption too
Positive energy power Q45；
ηopt=ηopt,i·ηend·ηIAM·ηtrack·ηgeneral (11)
Q3=Q3,i·ηend·ηIAM·ηtrack·ηgeneral,Q45=Q45,i·ηend·ηIAM·ηtrack·ηgeneral (12)
7) the photothermal conversion process in computing unit is calculated；
Its one-dimensional photothermal conversion computation model is established for computing unit thermal-collecting tube Parametric geometric model, using to spreading
Heat, conduction heat transfer, radiant heat transfer computational methods are calculated, obtain the computing unit in whole year by when photothermal conversion imitate
Rate, working medium caloric receptivity and outlet temperature etc..
7-1) single-phase convection heat exchange power calculating formula is formula (13) and the inlet and outlet conservation of energy in the endothermic tube of computing unit
Equation is formula (14).
q12=2 π R2nlh12(T2-T1),h12=Nu12λ1/(2R2),T1=(Tout+Tin)/2 (13)
q12=min(cp,outTout-cp,inTin) (14)
In formula, minFor tube inlet working medium mass flow of absorbing heat, kgm-1；Tin,ToutRespectively computing unit endothermic tube into
Export Temperature of Working, K；T1,T2Respectively import and export working medium mean temperature and heat absorption inside pipe wall mean temperature, K；cp,in,cp,outPoint
It Wei not computing unit endothermic tube inlet and outlet working medium specific heat capacity J (kgK)-1；R2For the bore that absorbs heat, m.
According to different Bottomhole pressure reynolds number Res1, Prandtl number Pr1With the choosings such as the draw ratio of 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：
The formula scope of application is, c=0.4 when 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 is calculated using Filonenko formula：
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 absorbed heat between pipe outer wall and inner wall：
q23=2 π λ23nl(T3-T2)/ln(R3/R2) (19)
7-3) radiant heat transfer to absorb heat between pipe outer wall and glass inside pipe wall calculates：
In formula σ be black body radiation constant, W (m2·K4)-1；
7-4) calculated by the heat flow of glass tube surfaces externally and internally：
7-5) heat convection between glass pipe outer wall and air and the calculation of radiation heat transferring between ambient enviroment：
According to different Rayleigh number Ra56, reynolds number Re56, Prandtl number Pr56It is changed Deng the outer convection current of different glass tubes is selected
Hot correlation；
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。
8) solar energy converging and photothermal conversion to all computing units connected in slot light collection solar energy heating circuit
The method that process is solved step by step；
Step 6), step 7) are repeated, to the solar energy converging of all computing units and photothermal conversion mistake connected in circuit
Cheng Jinhang is solved step by step, until the outlet parameter of the last one computing unit endothermic tube of circuit is calculated.By what is be calculated
Circuit outlet Temperature of Working is compared with circuit outlet design temperature, if the two is differed within 0.1%, circuit flow at this time
minMeet design requirement；It is on the contrary then adjust minValue and calculated again, until circuit outlet temperature is met the requirements.
It is wherein as follows for the specific method for solving of the middle computing unit in circuit：
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) by simultaneous equations (13)~(27), in known air temperature T6, environment temperature T7, computing unit import work
Matter temperature TinWith flow minIn the case of, computing unit outlet Temperature of Working T can be obtainedout, wall temperature T inside and outside endothermic tube2,T3、
Wall temperature T inside and outside glass tube4,T5, each heat flow value q12,q23,q34,q4,q5,q567。
8-3) parameter in circuit between each computing unit is transferred
In one collects hot loop, multiple computing units are included from circuit entrance to circuit outlet.List is calculated for each
Member, sender property outlet parameter are the suction parameter of next computing unit.The suction parameter of initial unit is inhaled equal to circuit
The suction parameter of heat pipe, the outlet parameter of the last one computing unit are equal to the outlet parameter of entire circuit endothermic tube.
9) by when calculate it is annual in each moment single circuit heat production power and by heat production power and the calculating moment institute
The time interval of representative is multiplied, then by the way that the single circuit quantity of heat production in each time interval to be added to obtain the complete of single circuit
Year quantity of heat production Ql,design。
10) the single circuit whole year heat production in the heat collecting field whole year quantity of heat production design requirement and step 9) in step 1)
Amount calculates circuit quantity N needed for resulting estimate collecting system to be designedl,design=Qs,required/Ql,design.Simultaneously according to step
2) setting in determines the circuit number of each subregion of heat collecting field.
11) each circuit whole year is calculated using step 5) to step 9) the method for each circuit in all subregions
Quantity of heat production, and pass through and be added each circuit whole year quantity of heat production to obtain collecting system whole year quantity of heat production Qs,design。
12) judge whether result of calculation meets design requirement by formula (28), if the whole year for the collecting system that design obtains
Quantity of heat production Qs,designMeet design requirement then to terminate to calculate；If being unsatisfactory for requiring, circuit number is adjusted to N 'l,designAfterwards
Return to step 11) continue to calculate, until requirement is reached.
1 slot light collection solar thermal collection system design method parameter list of table
Claims (8)
1. a kind of slot light collection solar thermal collection system design method, which is characterized in that comprise the following steps：
1) the annual quantity of heat production design requirement Q of slot light collection solar thermal collection system to be designed is determineds,required, it is 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
The thermal-arrest circuit moved towards and arranged on east-west direction by the U-shaped of drift angle forms, and each circuit is connected by several groove type heat collectors
It forms, each heat collector is mainly made of slot type speculum 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, establish the three-dimensional of collection hot loop
Geometrical model；
3) determine that each component optical parameter of slot light collection solar thermal collector and the hot physical property of thermal physical property parameter, heat-transfer working medium are joined
Number；
4) the inlet flow rate initial setting m in slot light collection solar energy heating circuit is determinedinWith out temperature setting value；
5) computing unit division is carried out to slot light collection solar energy heating circuit, i.e., with a 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 as one
Independent solar energy converging and photothermal conversion equipment；
6) solar energy converging process in computing unit is calculated：Its optical mode is established for computing unit 3-D geometric model
Type, using Monte Carlo ray tracking method carry out optical computing, obtain the computing unit in whole year by when optical efficiency,
The thermal power absorbed in real time in heat absorption tube outer surface and glass tube；
7) the photothermal conversion process in computing unit is calculated：It is established for computing unit thermal-collecting tube Parametric geometric model
Its one-dimensional photothermal conversion computation model, is calculated using convection current heat transfer, conduction heat transfer, radiant heat transfer computational methods, is somebody's turn to do
Computing unit in whole year by when photothermal conversion efficiency, working medium caloric receptivity and outlet temperature；
8) step 6) and step 7), the solar energy to all computing units connected in slot light collection solar energy heating circuit are repeated
Convergence is solved step by step with photothermal conversion process, until the outlet of the endothermic tube of the last one computing unit of circuit is calculated
Parameter compares the circuit outlet Temperature of Working being calculated and circuit outlet design temperature, if the two difference 0.1% with
It is interior, then loop mass flow m at this timeinMeet design requirement；It is on the contrary then adjust minValue and calculated again, until return
Until way outlet temperature is met the requirements；
9) by when calculate it is annual in each moment single circuit heat production power and will be representated by heat production power and the calculating moment
Time interval be multiplied to obtain single circuit quantity of heat production in the time interval, then by by single time in each time interval
Road quantity of heat production is added to obtain the annual quantity of heat production Q in single circuitl,design；
10) according to the heat collecting field whole year quantity of heat production design requirement Q in step 1)s,requiredIt is annual with the single circuit in step 9)
Quantity of heat production result of calculation estimates thermal-arrest circuit quantity N needed for heat collecting field to be designedl,design=Qs,required/Ql,design；Then, root
The thermal-arrest circuit quantity of each subregion of heat collecting field is determined according to the setting in step 2)；
11) each circuit whole year heat production is calculated using step 5) to step 9) for each circuit in all subregions of heat collecting field
Amount, and pass through and be added each circuit whole year quantity of heat production to obtain collecting system whole year quantity of heat production Qs,design；
12) judge whether result of calculation meets design requirement by formula (1), if the annual quantity of heat production of obtained collecting system
Qs,designMeet design requirement then to terminate；If being unsatisfactory for requiring, return to step 11 after the number of circuit is adjusted) continue to calculate, directly
Until design requirement is met；
2. slot light collection solar thermal collection system design method according to claim 1, it is characterised in that：The step 1)
Determine that geo-location parameter and meteorologic parameter include：
Heat collecting field local latitude to be designed, longitude and time zone data；The local annual constant duration of heat collecting field to be designed by when gas
Image data, the 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 design method according to claim 1, it is characterised in that：The step 2)
The basic geometrical structure parameter of slot light collection solar thermal collection system includes：The speculum Opening length L and width of single heat collector
Outer radius R in degree W, glass tube and endothermic tube effective length l, glass tube4,R5, outer radius R in endothermic tube2,R3；Heat collecting field subregion
Number and each subregion arrange that thermal-arrest circuit number accounts for the ratio of total loop number；The heat collector number of single collection hot loop,
Spacing d of each heat collector on Working fluid flow direction1ine；Spacing d between each row of heat collectorrow；
Establishing collection hot loop 3-D geometric model includes：The three of slot light collection solar energy heating circuit are established using mathematic(al) representation
The three-dimensional parameterized geometrical model of optical system is tieed up, the expression formula of the Parametric geometric model includes the speculum column of computing unit
Face equation, glass pipe outer wall cylindrical surface equation, glass inside pipe wall cylindrical surface equation and heat absorption pipe outer wall cylindrical surface equation.
4. slot light collection solar thermal collection system design method according to claim 1, it is characterised in that：The step 3)
In the thermal physical property parameter of definite heat collector optical parameter and thermal physical property parameter, heat-transfer working medium include：
Speculum, endothermic tube, the material of glass tube, reflectance of reflector ρm, cleanliness factor ρsoil, shape surface error standard deviation sigmam, glass
Pipe absorptivity αg, transmissivityτg, reflectivity ρgAnd refractive index θg, heat absorption pipe outer wall coating for selective absorption absorptivity α3, emissivity
ε3, endothermic tube thermal conductivity factor λ23, glass tube thermal conductivity factor λ45, the thermal conductivity factor λ of heat-transfer working medium1With specific heat capacity cp。
5. slot light collection solar thermal collection system design method according to claim 1, it is characterised in that：The step 6)
Solar energy converging process computational methods are as follows in computing unit：
6-1) heat collector trail angle β is calculated respectively using formula (2) and (3)cWith incidence angle θ of the sunlight on heat collector,
In formula, α, A are respectively local true solar time tsWhen sun altitude and azimuth, work as ts<A is positive value during 12h, works as ts>
A is negative value during 12h；αc,AcThe respectively inclination angle and azimuth of heat collecting field, wherein North and South direction cloth is pressed in each circuit on the whole
It puts and can have drift angle on east-west direction, the α when circuit southern side with respect to the horizontal plane upwarpscFor positive value, α on the contrarycFor negative value, and
The A when circuit southern side deviation eastcFor positive value, A on the contrarycFor negative value；
6-2) communication process of the solar radiation in computing unit is carried out using Monte Carlo ray tracking method to calculate
It is approximately a large amount of random light for carrying identical energy incident solar radiation；Light entering on computing unit speculum
It penetrates position to be determined by equally distributed probabilistic model, i.e., the random site P per beam light on the mirror is calculated using formula (4)m,
Wherein using computing unit mirror center as origin, mirror length, width and center vertical line direction are respectively X, Y, and Z axis is established
Speculum coordinate system, while the influence of the non-parallel angle of sunlight is calculated by the probabilistic model of non-uniform Distribution, wherein with
Machine light compared with incident beam primary optical axis radial direction drift angle δsolWith circumferential bias angle thetasolIt is calculated respectively by formula (5)；Then consider
The influence of incidence angle θ of the sunlight on heat collector is to get to sunlight incident direction vector I under speculum coordinate systemm；
Pm=[nL (ξ1-0.5) nW(ξ2-0.5) f(y)]T (4)
F (y) is groove type heat collector section type equation with parabolic form in formula；N is the heat collector number in computing unit；L and W difference
For the length and width of each heat collector speculum, m；δ be solar apparent diameter half, rad；
6-3) sunray is calculated with each component optical mechanism of computing unit
Judge whether light is blocked by adjacent groove type heat collector；Continue to calculate light and groove type heat collector reflection if not being blocked
Mirror, glass tube, the intersection point of endothermic tube, meanwhile, judge the two-phonon process of reflection, refraction and absorption of the light at each component；
6-3-1) when light reaches mirror surface, by formula (6) to determine whether reflecting, pass through if occurring to emit
Formula (7) calculates the reflective vector R of lightm；Wherein, the actual normal vector N of mirror mirrormConsider speculum shape surface error mark
Quasi- difference σmInfluence to reflection process, NmCompared with the radial direction δ of preferable normal vectorRWith circumferential bias angle thetaRIt is calculated using formula (8)；
0≤ξ5＜ ρm·ρsoil, reflect (6)
Rm=2 (Im·Nm)Nm-Im (7)
ρ in formulam,ρsoilRespectively reflectance of reflector, cleanliness factor；
6-3-2) when light reaches glass tube exterior surface, the optical effect mode of light is judged by formula (9), if light quilt
It absorbs the energy for then counting absorbed and records it and absorb position；It is calculated if generation reflects using the light law of refraction in glass
Reflect vector Reo；Light is calculated in the refracting process of glass pipe internal surface using identical method and the vector after being reflected
Rei；After light reaches heat absorption tube outer surface, the ray optics mode of action is judged by formula (10), if light is absorbed
Statistics, which absorbs energy and records, absorbs position；Using the diffusing reflection on orchid Bei Tedinglv calculating endothermic tubes if light is diffusely reflected
Vectorial Rc；
0≤ξ8＜ τg, refraction；τg≤ξ8＜ 1- ρg, absorb；1-ρg≤ξ8≤ 1, it reflects (9)
0≤ξ8＜ α3, absorb；ξ8≥α3, diffusing reflection (10)
τ in formulag,ρgRespectively glass tube transmissivity, reflectivity；α3For pipe outer wall coating for selective absorption absorptivity of absorbing heat；
It 6-3-3) next proceeds to calculate heat absorption tube outer surface to diffuse the intersection point of line and glass pipe internal surface, while using formula
(9) judge its optical effect process and use step 6-3-1)~6-3-2) and described in method continue to light in computing unit
Communication process calculate until light is absorbed or reflected and loses；According to above-mentioned calculating, finally statistics obtains perfect condition
The solar power Q that the moment absorbed each is calculated on lower endothermic tube and in glass tube3,i,Q45,i, and obtain computing unit herein
The perfect optics efficiency value η at momentopt,i, it is defined as Q3,iWith that can be received in notch type speculum opening area during the calculating
Maximum solar power ratio；
6-4) finally, the computing unit end caused by incidence angle of the sunlight in speculum plane of the opening is further considered
Optical loss/income coefficient ηend, due to non-perpendicular transmission of the sunlight on glass tube and caused by glass tube reflection optics damage
Lose coefficient, that is, incident angle modifier ηIAM, heat collector tracking error coefficient ηtrack, other composition error coefficients ηgeneralTo calculating
The actual optical efficiency η of computing unit at this moment is calculated using formula (11) in the influence of unit optical efficiencyopt；It adopts simultaneously
Computing unit heat absorption pipe outer wall actual absorption solar power Q is can be calculated with formula (12)3, glass tube actual absorption solar energy
Power Q45；
ηopt=ηopt,i·ηend·ηIAM·ηtrack·ηgeneral (11)
Q3=Q3,i·ηend·ηIAM·ηtrack·ηgeneral,Q45=Q45,i·ηend·ηIAM·ηtrack·ηgeneral (12)
In calculating formula, each ξ represents one and equally distributed random number, and all random numbers is obeyed in (0,1) section
Independently of each other；
In the calculation, the number in physical quantity subscript represents each structure and corresponds to parameter respectively, and wherein 1- heat absorptions intraductal working medium, 2- inhale
Heat pipe inner wall, 3- heat absorptions pipe outer wall, 4- glass inside pipe wall, 5- glass pipe outer wall, 6- surrounding airs, 7- ambient enviroments, meanwhile, object
Property parameter and the subscript of dust suppression by spraying represent the qualitative temperature of its used structure, ε3Represent heat absorption pipe outer wall with T3It is fixed
The emissivity of warm-natured degree, λ45Represent glass tube with internal and external walls mean temperature T45=(T4+T5)/2 are the heat conduction system of qualitative temperature
Number.
6. slot light collection solar thermal collection system design method according to claim 1, it is characterised in that：The step 7)
Computing unit in photothermal conversion process computational methods it is as follows：
7-1) single-phase convection heat exchange power calculating formula and inlet and outlet energy conservation equation formula are respectively in the endothermic tube of computing unit
Formula (13) and formula (14)；
q12=2 π R2nlh12(T2-T1),h12=Nu12λ1/(2R2),T1=(Tout+Tin)/2 (13)
q12=min(cp,outTout-cp,inTin) (14)
In formula, minFor tube inlet working medium mass flow of absorbing heat, kgm-1；Tin,ToutRespectively computing unit endothermic tube is imported and exported
Temperature of Working, K；T1,T2Respectively import and export working medium mean temperature and heat absorption inside pipe wall mean temperature, K；cp,in,cp,outRespectively
Computing unit endothermic tube imports and exports working medium specific heat capacity, J (kgK)-1；R2For the bore that absorbs heat, m；
According to different heat absorption Bottomhole pressure reynolds number Res1, Prandtl number Pr1With the draw ratio selection 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 when 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 is calculated using Filonenko formula：
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 absorbed heat between pipe outer wall and inner wall
q23=2 π λ23nl(T3-T2)/ln(R3/R2) (19)
7-3) radiant heat transfer to absorb heat between pipe outer wall and glass inside pipe wall calculates
In formula σ be black body radiation constant, W (m2·K4)-1；
7-4) calculated by the heat flow of glass tube surfaces externally and internally
7-5) heat convection between glass pipe outer wall and air and the calculation of radiation heat transferring between ambient enviroment
According to different Rayleigh number Ra56, reynolds number Re56, Prandtl number Pr56It is closed Deng the outer heat convection of different glass tubes is selected
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 design method according to claim 1, it is characterised in that：The step 8)
In the solar energy converging of all computing units connected in slot light collection solar energy heating circuit is carried out with photothermal conversion process
The method solved 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) by simultaneous equations (13)~(27), in known air temperature T6, environment temperature T7, computing unit import working medium temperature
Spend TinWith flow minIn the case of, computing unit outlet Temperature of Working T is obtainedout, wall temperature T inside and outside endothermic tube2,T3, in glass tube
Outer wall temperature T4,T5, each heat flow value q12,q23,q34,q4,q5,q567；
8-3) parameter in circuit between each computing unit is transferred
In one collects hot loop, comprising multiple computing units from circuit entrance to circuit outlet, for each computing unit,
Sender property outlet parameter is the suction parameter of next computing unit, and the suction parameter of initial unit is equal to entering for circuit endothermic tube
Mouth parameter, the outlet parameter of the last one computing unit are equal to the outlet parameter of entire circuit endothermic tube.
8. slot light collection solar thermal collection system design method according to claim 1, it is characterised in that：The step
12) the adjustment feeder number purpose method such as formula (28) in：
Circuit number after wherein adjusting is N 'l,design。
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