Environmental Engineering Reference
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to determine the thermal performance of parabolic trough collectors under different
operating conditions.
Garcia-Valladares and Velasquez (2009) developed a detailed numerical model for
a single pass and double pass solar receiver and validated it. The governing equations
inside the receiver tube, together with the energy equation in the tube walls and cover
wall and the thermal analysis in the solar concentrator were solved iteratively in a
segregated manner. The single-pass solar device numerical model has been carefully
validated with experimental data obtained by Sandia National Laboratories (SNL).
The effects of recycling at the ends on the heat transfer are studied numerically and
show that the double-pass arrangement can enhance the thermal efficiency compared
with the single-pass.
Cheng et al. (2010) in their contribution examined the solar energy flux distri-
bution on the outer wall of the inner absorber tube of a parabolic solar collector
receiver by adopting the Monte Carlo Ray-Trace Method (MCRT Method). They
found that the non-uniformity of the solar energy flux distribution is very large.
Three-dimensional numerical simulation of coupled heat transfer characteristics in the
receiver tube is calculated and analyzed by combining the MCRT Method and FLU-
ENT software, in which the heat transfer fluid was the Syltherm 800 liquid oil and the
physical model was the LS2 parabolic solar collector from the testing experiment of
Dudley et al. (1994). Temperature-dependent properties of the oil and thermal radia-
tion between the inner absorber tube and the outer glass cover tube are also taken into
account. Compared with test results from three typical testing conditions, the average
difference is within 2%.
Gong et al. (2010) presented an optimised model and tested China's first high tem-
perature parabolic trough receiver. The model is written in Matlab and computes the
receiver's major heat loss through the glass envelope, and then systematically analyzes
the major influence factors of heat loss in both 1-D and 3-D. Comparison shows the
original 1-D model agrees with the 'ends of the receiver covered test' while remarkably
deviating from the 'ends exposed' test. For the purpose of identifying the influence of
the receiver end on total heat loss, an additional 3-D model was built using a CFD
software to further investigate the different heat transfer processes of receiver's end
components. The 3-D end model is verified by heating power and IR temperature
distribution images in the test. Combining the optimized 1-D model with the new
3-D end model, the comparison with test data shows a good agreement.
He et al. (2011) used a coupled simulation method based on Monte Carlo Ray
Trace (MCRT) and Finite Volume Method (FVM) to solve the complex coupled heat
transfer problem of radiation, heat conduction and convection in a parabolic trough
solar collector system. A coupled grid checking method is established to guarantee
the consistency between the two methods and the validations to the coupled simula-
tion model were performed. The heat flux distribution curve could be divided into
4 parts: shadow effect area, heat flux increasing area, heat flux reducing area and
direct radiation area. The heat flux distribution on the outer surface of absorber tube
was heterogeneous in the circumferential direction but uniform in the axial direction.
Finally, the concentrating characteristics of the parabolic trough collectors (PTCs) were
analyzed by the coupled method, the effects of different geometric concentration ratios
(GCs) and different rim angles were examined. The results show that both variables
affect the heat flux distribution.
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