Summary
The energy conservation equations are solved to determine the transient behaviour of a solar power plant, made of linear concentrators. The equations are solved by the finite-difference method, assuming typical project parameters and the available experimental data. Different physical and geometrical configurations are considered; the results are shown and discussed in order to supply useful indications for the design of a solar power plant.
Riassunto
Si risolvono le equazioni di conservazione dell'energia per determinare il comportamento in regime transitorio di una centrale solare, costituita da concentratori parabolici lineari. Le equazioni sono risolte con il metodo delle differenze finite assumendo tipici parametri di progetto e i dati sperimentali disponibili. Si considerano differenti situazioni fisiche e geometriche; si analizzano e discutono i risultati, al, fine di fornire indicazioni sul progetto di una centrale solare.
Резюме
Решаются стационарные уравнения переноса тепла для определения профилей темиературы в диатермическом масле, протекающем через линейный бойлер, расположенный в фокальной линии цилиндрических параболических солнечных концентраторов. Для решения уравнения используется метод конечных разностей, предполагая профили скоростей Никурадзе и используя имеющиеся экспериментальные данные для определения граничных условий и оценки параметров уравнения. Рассматривается система решений для некоторых физических и геометрических ситуаций. Проводится обсуждение пректа солнечной силовой установки.
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Abbreviations
- R i :
-
is the internal radius of the tubular boiler
- h i :
-
the fluid boiler thermal-exchange coefficient
- T M i (x,t) :
-
the boiler temperature
- T F i (x,t) :
-
the fluid temperature in the boiler
- m :
-
the fluid mass flow
- C F :
-
the fluid specific heat
- ϱF :
-
the fluid density
- S F i :
-
the fluid section area in the boiler
- α:
-
the collector equivalent absorbitivity
- ω:
-
the collector equivalent emissivity
- P o(t):
-
the solar-flux intensity (direct only)
- cosi :
-
the cosine of the solar-ray incident angle on the boiler
- P L(T M i ):
-
the thermal losses of the boiler unit length
- ϱ M i ,C M i ):
-
the density and the specific heat of the boiler
- S F i :
-
the boiler section area
- R F0 :
-
the radius at the inside of the external pipe
- R M0 :
-
the radius at the outside of the external pipe
- h 0 :
-
the thermal-exchange coefficient between the fluid and the external pipe
- T M0 (x,t):
-
the external-pipe temperature
- T F0 (x,t):
-
the fluid temperature in the external pipe
- S F0 :
-
the fluid section area in the external pipe
- ϱ M0 , C M0 :
-
the density and the specific heat of the external pipe
- S M0 :
-
the section area of the external pipe
- k v :
-
the thermal conductivity of the heat insulator
- T v(r, t):
-
the heat insulator temperature
- ϱ v ,C v :
-
the density and the specific heat of the heat insulator
Literatur
A. B. Meinel andM. P. Meinel:Energy transfer in a large scale thermal solar power farm, inProceedings of the I Course in Solar Energy Conversion, Procida, September 1974.
O. Barra, M. Conti, E. Santamato, R. Scarmozzino andR. Visentin:Simulazione delle prestazioni di una centrale solare costituita da collettori parabolici uniassici, dotati di un sistema di orientamento ad 1 grado di libertà, a differenti latitudini, inRassegna Italiana di Eliotecnica (Settembre 1976).
O. Barra, M. Conti, L. Di Stefano, E. Santamato, R. Scarmozzino andR. Visentin:Efficiency tests on a prototype of linear parabolic concentrator for the conversion of the solar energy into heat at medium and high temperatures, inProceedings of the COMPLES International Meeting, U.P.M. Dhahran, Saudi Arabia, November, 2–6, 1975.
O. Barra, M. Conti, L. Correra andR. Visentin:Calcolo delle efficienze di collettori lineari nella conversione termica della radiazione solare, to be published onRassegna Italiana di Eliotecnica.
F. Kreith:Principles of Heat Transfer, 3rd edition (New York, N. Y., 1973).
W. M. Kays andH. C. Perkins:Forced convection, internal flow in ducts, inHandbook, of Heat Transfer, edited byW. M. Rohsenow andJ. P. Harnett (New York, N. Y., 1973).
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Barra, O., Conti, M., Correra, L. et al. Transient temperature variations in the primary network of a solar power plant. Il Nuovo Cimento C 1, 185–195 (1978). https://doi.org/10.1007/BF02524838
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DOI: https://doi.org/10.1007/BF02524838