Linear Fresnel Collector Receiver: Heat Loss and Temperatures

Heimsath, Anna; Cuevas, F; Hofer, A.; Nitz, Peter; Platzer, Werner

doi:10.1016/j.egypro.2014.03.042

Cited by 40 publications

(18 citation statements)

References 3 publications

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“…Like previous researchers, who mostly considered a constant temperature on the HTF pipes' outer walls, the effect of solar irradiation on the pipe outer surfaces is modeled by a constant temperature on the pipes' outer surface. This assumption has been widely used by previous researchers for a single-pipe (Haberle et al, 2002, Heimsath et al, 2014 or a multi-pipe (Pye, 2008;Facão and Oliveira, 2011;Sahoo et al, 2012;Sahoo et al, 2013a;Sahoo et al 2013b;Lai et al, 2013) LFR receiver. The resulting thermal re-radiation and natural convection (collectively called conjugate heat transfer) is, however, calculated by the CFD model.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a trapezoidal cavity absorber for the Linear Fresnel Reflector

2015

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To increase the efficiency of Concentrated Solar Power (CSP) plants, the use of optimization methods is a current topic of research. This paper focuses on applying an integrated optimization technology to a solar thermal application, more specifically for the optimization of a trapezoidal cavity absorber of an LFR (Linear Fresnel Reflector), also called a Linear Fresnel Collector (LFC), CSP plant. LFR technology has been developed since the 1960s, and while large improvements in efficiencies have been made, there is still room for improvement. Once such area is in the receiver design where the optimal cavity shape, coatings, insulation thickness, absorber pipe selection, layout and spacing always need to be determined for a specific application. This paper uses a commercial tool to find an optimal design for a set of operating conditions. The objective functions that are used to judge the performance of a 2-D cavity are the combined heat loss through convection, conduction and radiation, as well as a wind resistance area. In this paper the effect of absorbed irradiation is introduced in the form of an outer surface of pipe temperature. Seven geometrical parameters are used as design variables. Based on a sample set requiring 79 CFD simulations, a global utopia point is found that minimizes both objectives. The most sensitive parameters were found to be the top insulation thickness and the cavity depth. Based on the results, the Multi-Objective Genetic Algorithm (MOGA) as contained in ANSYS DesignXplorer is shown to be effective in finding candidate optimal designs as well as the utopia point.

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Section: Introductionmentioning

confidence: 99%

Optimization of a trapezoidal cavity absorber for the Linear Fresnel Reflector

2015

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“…This standard draft was proposed by the Spanish standardization Committee AEN/CTN 206/SC 117 "Thermoelectric solar energy systems" in AENOR and is based on the UNE standard draft under preparation for reflectors. For heat loss and temperatures of receivers with a secondary reflector and non-evacuated absorber (Cavity-Receiver) the thermal interaction between mirror and receiver has to be taken into account (Heimsath et al 2014b).…”

Section: Discussionmentioning

confidence: 99%

IEA SHC Task 49/IV - Deliverable A3.1 - Guideline on testing procedures for collectors used in solar process heat

Fahr¹,

Krämer²

2015

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IEA Solar Heating and Cooling ProgrammeThe Solar Heating and Cooling Technology Collaboration Programme was founded in 1977 as one of the first multilateral technology initiatives ("Implementing Agreements") of the International Energy Agency. Its mission is "to enhance collective knowledge and application of solar heating and cooling through international collaboration to reach the goal set in the vision of solar thermal energy meeting 50% of low temperature heating and cooling demand by 2050.The members of the IEA SHC collaborate on projects (referred to as "Tasks") in the field of research, development, demonstration (RD&D), and test methods for solar thermal energy and solar buildings.A total of 57 such projects have been initiated, 47 of which have been completed. Research topics include:

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“…To make sure to be able to compare both methods on the very same reproducible basis, and to avoid a potential error in the conclusions for the comparison of the two methods, heat loss coefficients are not determined in the subsequent parameter identifications. They are set constant to characteristic values of an evacuated glass envelope receiver ( = 0,0399 W/(mK) and = 0,0011 W/(mK²) ), which were obtained by simplified heat loss simulations with a thermal resistance model [14].…”

Section: Boundary Conditions Of Heat Loss Parametersmentioning

confidence: 99%

Comparison of Two Different (Quasi-) Dynamic Testing Methods for the Performance Evaluation of a Linear Fresnel Process Heat Collector

et al. 2015

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A small-scale Linear Fresnel Collector (LFC) for the generation of process heat has been tested by Fraunhofer ISE; its performance was evaluated by means of two different methods. The first is a quasi-dynamic testing method performed according to the testing standard ISO 9806:2013, with modifications in the model to accurately describe LFCs. Due to the two-dimensional Incidence Angle Modifier (IAM) of an LFC, an iterative multi-linear regression (MLR) approach has been developed to be able to comprehensively evaluate the optical performance. The second method is a dynamic testing method based on a parameter identification incorporating a multi-node/plug-flow collector model without strict restraints on mass flow and inlet temperature stability. Both methods are briefly described in their conceptual design and their basic requirements, revealing their similarities and differences. Each method is then applied to real measurement data from an LFC, assessing practicability and identification accuracy. For both methods, the mean absolute difference between identified IAM values and results from ray tracing fell in a range of 0.013-0.017, leading to a similar accuracy in LFC performance evaluation. Differences in optical efficiency between the two methods are smaller, with an average absolute difference below 0.0098, even when using different measurement data and simulation models. Thus the dynamic method represents a good starting point for the further development of an alternative dynamic testing and evaluation method with more flexibility than the current testing standard. This will be significant when evaluating large-scale concentrating collectors and collectors with direct steam generation.

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Linear Fresnel Collector Receiver: Heat Loss and Temperatures

Cited by 40 publications

References 3 publications

Optimization of a trapezoidal cavity absorber for the Linear Fresnel Reflector

Optimization of a trapezoidal cavity absorber for the Linear Fresnel Reflector

IEA SHC Task 49/IV - Deliverable A3.1 - Guideline on testing procedures for collectors used in solar process heat

Comparison of Two Different (Quasi-) Dynamic Testing Methods for the Performance Evaluation of a Linear Fresnel Process Heat Collector

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