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This study presents the optical improvement of a high flux solar simulator (HFSS) with controllable flux-spot capabilities developed for researching solar thermal and thermochemical processes. The HFSS is comprised of seven Xenon arc lamps coupled with ellipsoidal reflectors, a servo-controlled attenuator curtain, and three-axes linear test bench....
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... The performance of these simulators was evaluated based on the radiation flux distribution, peak flux, the power intercepted on a target plane, and transfer efficiency. Moreover, numerical models based on the Monte-Carlo Ray Tracing (MCRT) method were employed for the design and configuration improvement of HFSSs, including Tracepro [36], FRED [37], VeGas [38], and Opsira [39]. The geometry and spatial spectrum distribution of emitting arc within the lamp greatly impact the ray reflection and collection on the target plane, which was usually simplified as uniform emitting in the existing studies [40][41][42]. ...
Utilizing highly concentrated solar power for thermochemical processing as one of the extraterrestrial In-Situ Resource Utilization (ISRU) applications has been highlighted as an essential technique to support deep-space exploration in the future. Multi-source High-Flux Solar Simulators (HFSSs) are widely employed to provide stable irradiance for indoor solar thermal experiments. Meanwhile, numerical modeling that can characterize the radiation transport mechanisms within the solar thermal system has been developed for performance evaluation before field trials. However, significant differences between simulated and measured flux distributions were shown for existing models developed based on the Monte-Carlo Ray-tracing (MCRT) method, which have been attributed to only one or two specific reasons. In this paper, we proposed a comprehensive analysis of the concentration characteristics of a 42kW metal-halide lamp HFSS, developed at Swinburne University of Technology, considering the effect of five aspects. The flux distribution, uniformity, and vector distribution under different configurations were compared to quantify the influence of these factors on receiving irradiance. The suitable arc size, reflector shape, and reflector surface properties of the existing HFSS have also been numerically determined to improve the model and reduce the Root Mean Square Error (RMSE) for the lamp array from 38.2% to 8.3%. This research provides a potential pathway to numerically predict the radiation transfer performance of HFSSs and determine the suitable configuration for desired solar thermochemical applications.
... MCRT codes have been created for modeling and enhancing the optical performance of solar simulators such as the free and open-source MCRT code VEGAS, which has been widely implemented for the development of multilamp HFSSs [3,8,12]. In addition, commercially available ray-tracing software such as TracePro has been extensively employed for designing improved solar simulators [9,13,26]. In this study, TracePro is utilized for the optical modeling of HFSSs. ...
... This geometry provides the highest source-to-target radiative transfer efficiency. The radiative transfer efficiency η rad is the rate at which the light power emitted from the arc light source, P rad , placed at focus F 1 of the ellipse, is redirected toward a receiver, P rec , placed at focus F 2 [26], as shown in Fig. 2. From Fig. 2, a and b are the semimajor and minor axes, and the distance between the foci F 1 and F 2 is the focal length. The equation for estimating the radiative transfer efficiency in this study is described as ...
... In this work, the commercially available MCRT software TracePro (Lambda Research) is employed for evaluating the optical performance of different ellipsoidal reflectors for HFSSs [30]. TracePro has been widely implemented in the development of HFSS applications [7,9,13,16,26]. For instance, TracePro [18]. Units in millimeters. ...
High flux solar simulators are artificial solar facilities developed to imitate the on-sun operations of concentrating solar power technologies but under a well-controlled lab-scale environment. We report the optical enhancement of different high flux solar simulators for solar thermal and thermochemical applications. The solar simulator enhancement is numerically conducted by optimizing the geometry of ellipsoidal reflectors at focal lengths of 1600, 1800, and 2000 mm. The Monte Carlo ray-tracing technique is employed to evaluate the optical performance of different reflector designs. The typical seven-lamp solar simulator arrangement in hexagonal configuration is modeled to analyze the optical performance at different focal lengths. In addition, different xenon arc lamps are modeled with rated powers of 3000, 4000, 4500, and 5000 W for assessing the radiative flux characteristics of the proposed solar simulators. After the optimization, theoretical results show that peak fluxes and radiative powers of and 5.06–10.4 kW, respectively, can be achieved with the proposed designs of solar simulators for the different rated powers. Compared with a commercial reflector, theoretical peak flux and power can be improved up to 36% and 17.9%, respectively, with the proper combination of lamp-reflector units. We provide design alternatives to select a more suitable light source at low-rated powers ( ) and different focal lengths of the reflector, which simplifies the complexity of the design and improves the performance of solar simulators.
... The HFSS implemented in this study is comprised of seven 2.5 kW e xenon arc lamps coupled with 2000 mm focal length ellipsoidal reflectors, a servo-controlled shutter curtain and three-axes linear test bench. Detailed technical information about this facility can be found in (Martínez-Manuel et al., 2019). The HFSS xenon lamp array provides artificial concentrated solar radiation with a suitably scaled blackbody spectrum of about 6000 K, similar to that of the solar spectrum (5777 K) (Bader et al., 2015). ...
... Furthermore, the emission spectrum of xenon lamps resembles that of the sunlight with an air mass of 1.5 owing to their blackbody color temperature, as discussed in (Gallo et al., 2017). These types of xenon lamps (2.5 kW e ) have already been characterized and implemented for conducting solar thermal and thermochemical research (Martínez-Manuel et al., 2019;Levêque et al., 2016). ...
Solar Absorber Coatings (SACs) are widely used materials for improving thermal efficiencies of solar receivers. Traditionally, these SACs are investigated using heat treatments to test their optical-thermal properties; however, tests under concentrated flux conditions are still required. In this work, the thermal efficiency of different SACs is experimentally evaluated and compared. The analyzed SACs are: (1) Pyromark®2500, (2) Solkote®, (3) Thurmalox®250, (4) Comex® and (5) a new Soot from Forest Biomass (SFB) based coating. To assess the SACs performance, a High Flux Solar Simulator along with a calorimetric test bench are implemented under a well-controlled indoor environment applying two levels of concentrated irradiance of 100 ± 3 kW/m2 and 415 ± 12 kW/m2 named low and high flux level, respectively. Results show that, for a low flux level, the analyzed coatings present thermal efficiencies in a range from 91.74% to 83.24%, exhibiting a slightly close performance in most of the cases. Correspondingly, for a high flux level, the efficiencies range from 88.69% to 72.69%, with Pyromark®2500 being the most efficient in both cases. In addition, variations in the optical properties are reported for the experimental campaign with the high flux level, observing slight changes in the spectral absorptance and emittance. From these results, Pyromark presents the highest drop in solar absorptance of 1.22%, which is attributed to microcracks observed through the Scanning Electron Microscope (SEM). Thus, the presented approach can provide valuable information about the effects that concentrated flux levels can have in the optical-thermal performance of the analyzed samples.
... By comparing simulations against experimental results, the relative deviation of total radiative power was reported in 4.9%. Furthermore, TracePro® was utilized as the main tool in author's previous work for the optical improvement of a HFSS providing excellent agreement between simulated and experimental results within the 4.6% of relative error [39]. Therefore, theoretical results predicted from the optical design of the multi-lamp LFSS in this study are considered highly reliable. ...
... Consequently, the parabolic reflector surface was configured with a specular reflectance coefficient of 94.86%, absorptance of 5% and BRDF of 0.14%. The surface properties of the shutter curtain were considered as perfect absorbers, because the objective is to analyze the light beams behavior (non-uniformity) on the target plane after passing through an obstructing element, the shutter [39]. Correspondingly, the target is optically configured as perfect absorber in order to estimate the total radiative flux distribution on it. ...
Solar simulators are key facilities for conducting solar research and certification tests under a well-controlled environment. This study presents the optical design optimization of a modular low flux solar simulator to improve solar technology qualification testing. The optical system was designed as a multi-lamp array of 26 subunits. Each subunit consists of a 575 We metal halide lamp and a parabolic reflector. The Monte Carlo ray tracing technique was used for analyzing the optical performances of the proposed design. Reflector design parameters were analyzed in detail for optimizing the uniformity of the flux distribution on the target. Results show that an average flux of 1198 W/m2 over a target area of 2000 mm × 1000 mm, with a conversion efficiency of 25.7% and a sustained non-uniformity of only 1.4% was numerically achieved, predicting a Class A solar simulator for large target areas. A shutter curtain was modeled and introduced between the light source and the target for flux regulation, achieving average flux levels ranging from 1162 to 105 W/m2 with a resolution of approximately 100 W/m2. The modular nature of this design has the great advantage that it could be easily scaled according to the test requirements of potential solar systems.
... The peak flux values vary between 0.9 and 21.7 MW/m 2 . Most of these devices have a modular design and use elliptic reflectors and xenon lamps [9,[40][41][42]. However, one solar simulator is equipped with Fresnel concentrators (Fig. 2) instead of reflectors, reaching 20 kW rad with twelve 7 kW el xenon lamps [43]. ...
... The variation of the distance between reflector and target has an impact on the peak flux and the projection size [87]. For this method, the target can be moved as well as single reflector modules [42,88]. This is suitable for larger target areas, because in this case the spillage level is relatively low. ...
... By combining this method with the reflector defocus, the uniformity can be increased. For this strategy, ray tracing algorithms can be used to predict the flux distribution and to compute the positions of each simulator unit [42,43]. ...
High-flux solar simulators are research-grade sources of artificial radiation mimicking optical characteristics of concentrating solar systems. They allow for experimental evaluation of high-temperature solar thermal devices and materials under controlled and reproducible conditions. In this study, we demonstrate the application of close-range photogrammetry in tandem with radiometry to optically align radiation modules of a multi-source high-flux solar simulator and to characterize its radiative output. The photogrammetric setup consists of photogrammetry targets, a digital camera and photogrammetry software. The radiometric measurements are conducted using mobile Lambertian targets, a heat flux gauge, and a complementary metal-oxide semi-conductor camera equipped with neutral density filters. An iterative procedure for adjusting lamp positions allows obtaining optical configurations of radiative modules meeting experimental requirements of high and ultra-high temperature solar thermal and thermochemical research. Close-range photogrammetry is demonstrated to be a convenient and effective method to obtain the as-built geometric configuration of the solar simulator setup. We report characteristics of an example radiative module configuration for a subset of six radiation modules. The peak and mean radiative fluxes over a 60-mm diameter flat target located in the focal plane are 3080 kW m⁻² and 1135 kW m⁻², respectively. The mean aiming error, defined as the average distance between theoretical and actual aiming points in the focal plane, is reduced from 37.20 mm to 4.50 mm for the pre- and post-alignment configurations, respectively.
This chapter describes the basic relations, components, classifications, and applications of concentrating optical collector systems for solar thermal and thermochemical applications. Selected optical studies of laboratory-scale and full-scale concentrating collector systems are presented, in particular for high-temperature solar thermochemical processing.
The indoor solar simulator is an excellent supply device for high solar flux applications, but usually suffers from the low flux under a large light area and unadjustable light distribution. In this work, a 130 kWe indoor solar simulator with tunable ultra-high flux in a projection area of 200 mm diameter is designed and established. 13 of 10 kWe xenon short-arc lamps and reflectors are coupled to make the flux be concentrated to a spot. Besides, a direct measure system consisting of a Gardon gauge and a two-dimensional moving unit is proposed to map the flux distribution. The expanded uncertainty is 7.46% with a converge factor of 2, compared with the conventional indirect camera-based method with an error up to 50%. Up to 7 lamps are simultaneously measured. The Monte Carlo method is adopted to analyze flux distributions of individual lamps as well as the whole lamp group, which coincides well with the experimental data. When the input electric power is 11.12 kW, the electric-to-light conversion efficiency is 31.60% ± 2.36% on the focus plane. The peak flux reaches 11.267 ± 1.571 MW/m² and a mean flux amounts to 1.054 ± 0.079 MW/m² in a projection area of 200 mm diameter. Both the distribution and non-uniformity of irradiation flux are tunable. By reducing the power of the central lamp to the half and defocusing the target, the distribution non-uniformity of the light intensity can be remarkably reduced from 68.87% to 18.59% in a projection area of 60 mm diameter. The developed device will provide a reliable source for indoor experiments.
