Optimization of Design and Process Parameters for Maximized and Stable Solar Receiver Efficiency

Ophoff, Cédric; Korotunov, S. Yu.; Özalp, Nesrin

doi:10.1615/tfec2017.emi.018225

Cited by 7 publications

(7 citation statements)

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“…Aforementioned constraints listed circularity as a primary requirement. This follows from the heat flux characterization of the 7 kW solar simulator, used in the experimental setup, which showed strong resemblance of the obtained flux map with a Gaussian distribution [10,11]. Similarly, this approximation of the acquired flux density map also applies at larger scale solar concentrator facilities [12][13][14].…”

Section: Evolution Of the Aperture Areasupporting

confidence: 53%

“…The 3 mm thick disc is aligned flush with the reactor front flange such that reradiative losses through the aperture are significantly diminished. The rotary aperture and iris mechanism had previously been benchmarked against each other [10]. Results of this study showed that overall higher reactor temperatures were achieved with the rotary aperture for equivalent aperture sizes.…”

Section: Aperture Conceptsmentioning

confidence: 95%

“…The optical model was obtained from fitting numerical and experimental flux data [10]. TracePro ® optical software, which adopts the Monte Carlo ray tracing algorithm, was used for this optical analysis [15].…”

Section: Optical Performance Analysismentioning

confidence: 99%

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An Overview of Variable Aperture Mechanisms in Attempt to Control Temperature Inside Solar Cavity Receivers

Ophoff

Najafabadi

Bogaerts

et al. 2018

Proceeding of 3rd Thermal and Fluids Engineering Conference (TFEC)

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In solar thermal research, there is a lot of attention has been paid on optimal design of solar reactors and cavity receivers in order to overcome inherent technical challenges. While many of these studies focus on the geometry and flow optimization of the reactor/receiver, few have focused on control of light entry into the cavity via auxiliary embedded mechanisms. Because the natural fluctuation of solar radiation affecting the thermal behavior of these reactor/receivers during daytime, it is important to address this challenge. In order to cope with transient nature of solar energy, several modular devices have been conceived. They are designed based upon concepts featuring control of set of blades or interchanging apertures to adjust light entry. These techniques yield promising performance on maintaining the desired reactor temperature and solar to fuel efficiencies. Towards that effort, an extensive fundamental background in designing, manufacturing, and testing of such mechanisms has been accumulated by our research group. This paper provides an overview of three successful mechanical apertures developed by our group to regulate flux entry into solar thermal receivers. The overview covers methodological aspects commonly encountered during the design process. A thorough comparison of performance records of these mechanisms are given per their actuation methods. Effect of each aperture mechanism and their individual change of cross-sectional shape is being evaluated through extensive optical simulation. The simulation results give insights on their respective optical performance by quantifying their radiative energy gain and losses. The paper also presents a numerical method coupling optical model to a thermodynamic analysis yielding accurate estimation of reactor temperature per experimental validation. Finally, numerical simulation showed that closed loop control of aperture size can efficiently regulate the temperature throughout a sunny day. Results of this research highlight the advantage of adopting variable apertures in solar cavity receivers.

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Section: Evolution Of the Aperture Areasupporting

confidence: 53%

Section: Aperture Conceptsmentioning

confidence: 95%

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An Overview of Variable Aperture Mechanisms in Attempt to Control Temperature Inside Solar Cavity Receivers

Ophoff

Najafabadi

Bogaerts

et al. 2018

Proceeding of 3rd Thermal and Fluids Engineering Conference (TFEC)

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“…2. Further details about the geometric constraints, torque calculation, and other aspects of the design methodology can be found elsewhere [26].…”

Section: Variable Aperturementioning

confidence: 99%

“…Also, an XYZ slider is used to accurately control the position of the target at the focal plane, with steps of 0.08 lm in three different axes. Further details of this setup and methodology can be found elsewhere [26].…”

Section: Optical Characterization Of the Solar Simulatormentioning

confidence: 99%

Numerical and experimental investigation of heat transfer in a solar receiver with a variable aperture

Abuseada

Özalp

Ophoff

2019

International Journal of Heat and Mass Transfer

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Variable aperture can assist in maintaining semi-constant temperatures within a receiver's cavity under transient solar loading. An in-house code has been developed to model a receiver and effectively control its components to achieve semi-constant temperatures under transients. The code consists of a full optical analysis performed via the Monte Carlo ray tracing method in addition to a transient two-dimensional heat transfer analysis. The system studied consists of a cavity type solar receiver with 60 mm radius fixed aperture on the cavity body, a variable aperture mechanism mounted on the receiver's flange, and a 7 kW Xenon arc solar simulator. A composite shape consisting of a hemisphere attached to a cylinder is proposed to model the Xenon arc. The in-house code has been experimentally validated through experimental tests for different input currents to the solar simulator, volumetric flow rates, and aperture's radii. The optical analysis was validated based on heat flux measurements, where it had percentage errors of 0.8, 0.5, 1.1, and 3.2% for the peak power, total power, half width, and half power. For the heat transfer model, percentage errors of 3.2, 2.9, and 5.3% at the inlet, center, and outlet sections of the receiver were determined for different flow rates using maximum input current and opening radius. The aperture mechanism was capable of maintaining an exhaust temperature of 250°C based on actual Direct Normal Irradiance data. Results showed that the variable aperture is a promising apparatus even in applications where the maximum temperatures are desired based on an observed optimum radius of 57.5 mm.

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Design and characterization of linear shape memory alloy actuator with modular stroke

Costanza

Radwan

Tata

et al. 2019

Procedia Structural Integrity

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Optimization of Design and Process Parameters for Maximized and Stable Solar Receiver Efficiency

Cited by 7 publications

References 0 publications

An Overview of Variable Aperture Mechanisms in Attempt to Control Temperature Inside Solar Cavity Receivers

An Overview of Variable Aperture Mechanisms in Attempt to Control Temperature Inside Solar Cavity Receivers

Numerical and experimental investigation of heat transfer in a solar receiver with a variable aperture

Design and characterization of linear shape memory alloy actuator with modular stroke

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