Compound Parabolic Concentrator Research Articles

Light-harvesting properties of photocatalyst supports—no photon left behind

AbstractIn this work, we set out to elucidate the light-harvesting properties of various random and ordered photocatalyst supports (PSs) with different macropore sizes. To accomplish this, we propose two studies of increasing relevance, enabled by computed tomography (CT) reconstructions and ray-tracing COMSOL Multiphysics simulations: (a) a 360-degree light release study approximating a PS situated within a compound parabolic concentrator (CPC) or cylindrical LED reactor with open ends; and (b) the same system as before but with closed ends. The ordered geometry is of interest, as it can be 3D printed at scale with a tailored morphology and porosity, and it can potentially be refined using machine learning models to optimize its light-harvesting properties. As will be shown, the local volumetric light absorption (LVLA) data suggests that an ordered PS with a more open pore interior and a smaller pore exterior would begin to approach the more isophotonic light-harvesting properties of random PSs.

Compound parabolic concentrator for LED-based underwater optical communication transmitter

Laser sources have been used at the transmitter unit of underwater wireless optical communication (UWOC) systems since their invention. In recent years, light-emitting diodes (LEDs) have begun to be used as UWOC transmitters due to their low cost, long lifespan, and high energy efficiency. However, data transmission distances in UWOC systems using bare LEDs and LED arrays with collimating lens are limited due to LED’s large divergence angles and insufficient gains provided by the low cost lens designs. In this paper, we propose to use a compound parabolic concentrator (CPC), whose transmission efficiency curve is very close to the ideal concentrator, as a collimator that narrows the divergence angle of LEDs to design low-cost UWOC transmitter with long communication distance. Using the Bouguer–Beer–Lambert channel model, we derived the received optical power expression at the receiver side for the LED-based UWOC system with CPC at the transmitter. Furthermore, unlike existing studies in the literature, the full spectrum of the LED has been taken into account when deriving the power expression. The results show that using the CPC collimator instead of a typical collimation lens in an LED-based UWOC system can narrow the divergence angle by approximately 10 times, resulting in a 70 dB increase in signal-to-noise ratio (SNR) at the receiver and up to a 20 times increase in the communication distance.

Spectral properties regulation for the performance improvement of solar-driven methane dry reforming reactor based on the photothermal synergistic catalysis

With the development of chemical industry, many chemical reactions are expected to be directly driven by solar energy. Among them, methane dry reforming (MDR) is a highly promising reaction system. Since all the energy required for MDR comes from solar energy, the temperature distribution and reaction characteristics in the reactor are determined by radiation transportation, and therefore regulating the optical properties according to the spectral distribution characteristics becomes necessary for improving the chemical conversion performance of the reactor. In this paper, aiming at the specific strengthening mechanism of different spectra in photothermal synergistic catalysis, the spectral response characteristics in the reactor were purposefully regulated, so as to achieve the improvement of reactor efficiency and reaction conversion performance. By adjusting the optical properties of compound parabolic concentrator (CPC) and porous catalytic absorber (PCA) in a cavity reactor, the CO2 conversion can be increased by 68.52%, the CH4 conversion can be increased by 54.48%, and the solar-fuel efficiency can be increased to 6.16%. This indicates that the selectivity of different bands of full spectrum can significantly affect the reactor performance. Through the above research, this paper aims to provide a new optimization idea for the photothermal reactor.

Low Concentrating Photovoltaic Geometry for Retrofitting Onto European Building Stock

Abstract The most appropriate low concentrating photovoltaic (LCPV) technology suitable for European buildings located in mid-high latitudes under both maritime and continental climatic conditions has been identified as the asymmetric compound parabolic concentrator (ACPC). To date, there is no published experimental data at different latitudes on the long-term performance of these systems at these latitudes nor how location would modify the optical characteristics of deployed systems. Previous theoretical research by the authors has demonstrated the superiority of the ACPC with this additional work experimentally confirming the robustness of the design. To investigate how seasonal and locational variations affect their measured technical performance two identical ACPC-LCPVs were installed, instrumented, and monitored at two different climatic locations (Uxbridge, UK, and Vevey, Switzerland) from May 2020 to September 2020. A valid comparative performance investigation characterizing two geometrically equivalent ACPC-based LCPV systems using real-life experimental data collected is presented in this paper. Locations at higher latitudes experience greater transverse angles more frequently compared to locations nearer the equator making ACPC geometries more appropriate than symmetrical concentrator configurations for building retrofit. This is shown in this paper over a latitudinal expanse of 31.35 deg for four separate locations; Tessalit (20.19 deg N, 1.00 deg E; Mali), Timimoun (28.03 deg N, 1.65 deg E; Algeria), Uxbridge (51.54 deg N, 0.48 deg E, UK), and Vevey (46.6 deg N, 6.84 deg E, Switzerland).

Concatenated backward ray mapping on the compound parabolic concentrator

Concatenated backward ray mapping is an alternative for ray tracing in 2D. It is based on the phase-space description of an optical system. Phase space is the set of position and direction coordinates of light rays intersecting a surface. The original algorithm (Filosa, ten Thije Boonkkamp and IJzerman in J Math Ind 11(1):4, 2021) is limited to optical systems consisting of only straight surfaces; we generalize it to accommodate curved surfaces. The algorithm is applied to a standard optical system, the compound parabolic concentrator. We compare the accuracy and speed of the generalized algorithm, the original algorithm and Monte Carlo ray tracing. The results show that the generalized algorithm outperforms both other methods.

Comparative energy metrics and annual efficiency analyses of CPC‐ETC integrated single slope solar desalting unit

AbstractThis paper deals with the investigation of N identical compound parabolic concentrator evacuated tubular collector included single slope solar desalting unit (N‐CPC‐ETC‐SSU) by incorporating energy metrics for solving contemporary issue of water scarcity in the society. It will contribute to the sustainable development of society and recede the dependency on fossil fuels, too. The energy metrics investigation is important for energy system because it talks about the feasibility of the system. The methodology consists of getting fundamental equations from energy balance equations. All fundamental equations with relevant data are fed to the code developed in MATLAB followed by the computation of overall energy and exergy. All types of climatic situations have been considered for the analysis. Data required for the same are accessed from IMD, Pune, India. The energy payback period, energy production factor, and life cycle conversion efficiency for N‐CPC‐ETC‐SSU have been calculated at eight number of collectors, 0.012 mass flow rate and 0.14 m water depth. Results of N‐CPC‐ETC‐SSU have been compared with results of SSU included with ETCs. Concludingly, energy payback period is lower by 6.41%, energy production factor is higher by 6.25% and exergy‐based life cycle conversion efficiency is higher by 96.39% for N‐CPC‐ETC‐SSU than N‐ETC‐SSU.

Solar Window Innovations: Enhancing Building Performance through Advanced Technologies

Building-integrated photovoltaic (BIPV) glazing systems with intelligent window technologies enhance building energy efficiency by generating electricity and managing daylighting. This study explores advanced BIPV glazing, focusing on building-integrated concentrating photovoltaic (BICPV) systems. BICPV integrates concentrating optics, such as holographic films, luminescent solar concentrators (LSC), Fresnel lenses, and compound parabolic concentrators (CPCs), with photovoltaic cells. Notable results include achieving 17.9% electrical efficiency using cylindrical holographic optical elements and crystalline silicon cells at a 3.5× concentration ratio. Dielectric CPCs showed 97.7% angular acceptance efficiency in simulations and 94.4% experimentally, increasing short-circuit current and maximum power by 87.0% and 96.6%, respectively, across 0° to 85° incidence angles. Thermochromic hydrogels and thermotropic smart glazing systems demonstrated significant HVAC energy savings. Large-area 1 m2 PNIPAm-based thermotropic window outperformed conventional double glazing in Singapore. The thermotropic parallel slat transparent insulation material (TT PS-TIM) improved energy efficiency by up to 21.5% compared to double glazing in climates like London and Rome. Emerging dynamic glazing technologies combine BIPV with smart functions, balancing transparency and efficiency. Photothermally controlled methylammonium lead iodide PV windows achieved 68% visible light transmission, 11.3% power conversion efficiency, and quick switching in under 3 min. Polymer-dispersed liquid crystal smart windows provided 41–68% visible transmission with self-powered operation.

Optimal design, construction and evaluation of symmetric compound parabolic concentrator integrated with photovoltaics system (CPC-PV)

To enhance the production and efficiency of photovoltaic systems, research has been conducted on various techniques including the use of compound parabolic reflectors (CPCs). A mathematical model is developed using the governing solar radiation and CPC geometry equations to optimize the geometrical parameters required for the experimental setup. The optimal values for the half acceptance angle and tilt angle were found to be 25° and 35°, respectively. Based on these optimal parameters, a laboratory setup was fabricated and evaluated. To compare the performance of our CPC-based system, three different panels constructed: a simple PV panel without a concentrator, a PV panel with a concentrator but without cooling (CPC-PV), and a PV panel with a concentrator and water cooling (CPC-PVT). Results showed that the use of a CPC with a concentration ratio of 1.7 in both modes, with and without cooling, led to a 10 % and 20 % increase in the output power, respectively, compared to the simple PV panel. In summary, this study demonstrates the effectiveness of using a CPC in enhancing the production and efficiency of photovoltaic systems. The mathematical model developed in this research can be utilized for optimizing the geometrical parameters required for the design of CPC-based systems. The experimental results obtained from this study indicate that the use of a CPC with water cooling can significantly improve the energy output of the photovoltaic system. These findings can aid in the design of cost-effective and efficient photovoltaic systems.

Research on the Model Construction and Characteristics of Solar Radiation Received by Solar Wing Coupled with Compound Parabolic Concentrator

Research on the Model Construction and Characteristics of Solar Radiation Received by Solar Wing Coupled with Compound Parabolic Concentrator

Effects of Outdoor Conditions on the Compound Parabolic Concentrator Performance

In this study, the effect of outdoor conditions(wind velocity and ambient temperature) on the thermalefficiency of a non-evacuated Compound ParabolicConcentrator solar collector (CPC) was investigated fortwo different flow rates. Matlab program was built, andsimulation results for different outdoor conditions werecompared with an actual outdoor data set that was takenat Misurata city, Libya. Although this study showed someeffects of outdoor conditions on the CPC collectorcomponent’s temperatures and heat losses, no importantinfluence on the collector efficiency was noticed.Therefore, even though wind velocity and ambienttemperature vary throughout the day, approximatingthem as constant values is a reasonable assumption. Massflow rate is the most important parameter that affects theCPC efficiency.

Performance modeling and cost optimization of a solar desalination system using forward osmosis with energy storage

This study presents the design and performance evaluation of a solar-driven water desalination system based on forward osmosis (FO) with thermally responsive ionic liquids (ILs). FO is a two-step process involving dilution of the ILs with water, followed by heating above a critical temperature to induce phase separation of liquid water from the IL. This regeneration step can be achieved by integrating FO with low-grade solar energy, which is abundant in regions that face severe water scarcity. A system design is presented that couples an FO membrane module with a compound parabolic concentrator solar collector and thermal energy storage to minimize solar intermittency and produce clean water at a distributed scale of 10 m3/day. To determine the optimal sizing of components in the system, a technoeconomic analysis using the TRNSYS software is performed with the goal of minimizing the levelized cost of water (LCOW). Notably, over 96 % of the energy required for regeneration comes from solar energy and/or the thermal energy storage (TES) in all cases, with auxiliary heat from electricity being used to maintain a continuous process. To evaluate the potential of solar-FO in three different locations within the United States, a case study is presented for Phoenix, AZ; San Diego, CA; and Atlanta, GA. The simulation results reveal that for a small-scale desalination system, LCOW values as low as $1.31/m3 can be attained, with the potential to approach $1/m3 by lowering the costs of the solar collector and FO module based on a sensitivity analysis.

Integration of solar thermal collectors and heat pumps with thermal energy storage systems for building energy demand reduction: A comprehensive review

Solar energy, coupled with innovative technologies, holds the promise of propelling buildings towards net-zero and carbon neutrality. In this regard, this review explores the integration of solar technologies, heat pumps, and thermal energy storage systems to reduce building energy demand. It thoroughly examines various types of solar thermal collectors (STCs), including both concentrating devices like compound parabolic concentrators and parabolic troughs, as well as non-concentrating designs such as flat plate and evacuated tube collectors. It examines innovative strategies for enhancing STC performance, such as alternative profiles for compound parabolic concentrators and the insertion of thermal fins in absorber tubes. Furthermore, the review categorizes solar-assisted heat pumps (SAHPs) into indirect expansion (IDX) and direct expansion (DX) systems, describing their advantages and limitations. It performs a comparison between IDX-SAHPs and DX-SAHPs, explaining their effectiveness and applicability. Eventually, the review explores thermal energy storage materials, categorizing them into sensible heat storage, latent heat storage, and thermochemical heat storage (TCHS). It discusses the advantages and disadvantages of each category, as well as notable materials within them. A comparative examination between open and closed systems for TCHS further enriches the discussion. Throughout the review, recent advancements and key findings from relevant studies are summarized in separate tables, offering valuable information into practical strategies for sustainable building energy systems. Regarding the provided sections, this review plays a crucial role in introducing scholars to practical methods employed in recent years to integrate the STCs with heat pumps and thermal energy storage systems.

Compact and Stable Diamond Quantum Sensors for Wide Applications

AbstractThis study proposes compact, highly sensitive, and stable diamond quantum sensors for a wide range of applications, including biomedical and energy electronics. For enhanced sensitivity and alignment precision within the objective field, a high‐quality, (111)‐oriented 12C‐enriched chemical vapor deposition (CVD) diamond, featuring a nitrogen‐vacancy (NV) axis in the (111) direction, is employed as the sensor. To increase the fluorescence collection efficiency, the laser beam is irradiated from the side surface of the CVD diamond, and fluorescence is detected using a compound parabolic concentrator (CPC) lens. The floor noise level of the magnetic field signal is 44 pT/Hz0.5. An Allan deviation of 1.2 pT over 1000 s of averaging demonstrates stability. This is attributable to the integration of a balancing circuit to cancel out laser noise, alongside mechanisms to compensate for temperature fluctuations and a copper housing to shield against electromagnetic field noise.

Full year performance analysis and steady state operation model for a stationary Shadeless solar thermal collector with a horizontal aperture for steam generation

This work documents a full-year performance of a new design of a non-tracking zero-latitude-tilt external compound parabolic concentrator (XCPC) solar thermal system called Non-tracking Asymmetric Shadeless (NASH) concentrator. The system has a horizontal-aperture design that offers several advantages in terms of land use efficiency because of zero row-to-row spacing, reduced capital costs, and improved heat management. The horizontal aperture (no tilt) design enables it to be scaled to a large area easily without lost area from row-to-row shading as experienced by a tilted design. The system was tested at the University of California Merced, Castle test facility for a full year. The data are analyzed to investigate the system efficiency and thermal energy generated during the year. The system generated 766 kWh/m2 during 2022 with annual efficiency of 41 %. A steady-state model is developed to predict the system performance based on the direct- and diffuse-light optical efficiencies, radiative and manifold heat losses, and observed soiling rate. The system efficiency decreased by up to 14 % over a month due to soiling in this test location. The model gives a good estimation of the steady-state operation during July and predicts the general annual trend of the generated thermal energy.

Experimental study on solar wall by considering parametric sensitivity analysis to enhance heat transfer and energy grade using compound parabolic concentrator and pulsating heat pipe

Enhancing high-grade and rapid thermal storage for solar energy utilization is of paramount importance in reducing building energy consumption. Therefore, this study combines the Compound Parabolic Concentrator (CPC) and Pulsating Heat Pipe (PHP) to propose an integrated CPC-PHP solar wall (CPC-PHP-SW) that can enhance solar energy grade and rapid thermal storage. The mixed working fluid for CPC-PHP-SW is developed to reduce the dependence on solar radiation intensity and facilitate PHP startup. Furthermore, the operating characteristics and heat transfer performances of the CPC-PHP-SW are studied experimentally under various factors, including solar radiation intensity, working fluid, and cooling temperature. Sensitivity analyses of these three factors on heat transfer performances are conducted using Multi-factor analysis of variance. Results highlight that solar radiation intensity is the most influential factor on heat transfer performance, followed by cooling temperature, and working fluid. Moreover, employing a CPC with a concentration ratio of 2 reduces thermal resistance by up to 56.46 %, while the maximum effective thermal conductivity increases by up to 129.65 %. A recommended methanol to water ratio is 1:3, which effectively copes with a wide range of solar radiation intensity. These findings provide valuable references for the design and application of CPC-PHP-SW in building envelopes.

A preliminary investigation of a novel solar-powered absorption-desiccant-radiant cooling system for thermally active buildings

Desiccant air-conditioning systems are considered a competitive alternative to conventional vapor compression cycles. However, the literature lacks detailed studies of such systems when coupled with thermally active buildings and powered by solar energy due to the complexity of modeling and controlling the system. In the present study, a novel hybrid desiccant-dehumidification-absorption system, driven by external compound parabolic concentrators (DDA-XCPC), is used to serve a typical office space in a hot climate zone. The entire system is modeled and simulated dynamically in the TRNSYS environment. The current study investigates the proposed system performance in terms of the achieved thermal comfort, energy consumption, solar fraction, life cycle costs, and carbon emissions. The results reveal superior thermal comfort levels with percentages of people dissatisfied below 5.6 %. The daily solar fraction ranged between 41 and 90 %, with an average of 49 %, whereas the coefficient of performance varied between 0.46 and 1.38 while having a season average of 0.86. Compared to a conventional system, driven by a gas boiler, the proposed system increased the life cycle costs by 6,824 USD due to the large capital investment of the solar thermal loop. However, each 1,000 USD of additional expenses was accompanied by a cutdown of 4,619 kg of CO2 emissions. Increments in the solar system’s capacity (i.e., solar collector area and storage tank volume) have adverse and favorable impacts on the economic and environmental performances, respectively. Therefore, the system can be a viable option whenever green energy production is prioritized and considerably incentivized.

High-Efficiency Vertical-Chip Micro-Light-Emitting Diodes via p-GaN Optimization and Surface Passivation

Micro-LEDs have found widespread applications in modular large-screen TVs, automotive displays, and high-resolution-density augmented reality glasses. However, these micron-sized LEDs experience a significant efficiency reduction due to the defects originating from the dry etching process. By controlling the current distribution via engineering the electrode size, electrons will be less concentrated in the defect region. In this work, we propose a blue InGaN/GaN compound parabolic concentrator micro-LED with a metallic sidewall to boost efficiency by combining both an optical dipole cloud model and electrical TCAD (Technology Computer-Aided Design) model. By merely modifying the p-GaN contact size, the external quantum efficiency (EQE) can be improved by 15.6%. By further optimizing the passivation layer thickness, the EQE can be boosted by 52.1%, which helps enhance the display brightness or lower power consumption.

Experimental study on a compact solar driven two-stage humidification-dehumidification desalination system with shared dehumidifier

The low-cost and low-grade solar driven humidification-dehumidification desalination is considered a promising process for small and medium capacity freshwater production. Nevertheless, the enhancement of the unit volume water production rate is hindered by the disparity in mass transfer coefficient and the incongruity between heat and mass flow rate in the humidification and dehumidification process. This paper proposes a compact solar driven two-stage humidification-dehumidification desalination system with shared dehumidifier. It contains two humidifiers and a dehumidifier, wherein the dehumidifier is stacked between the vertically placed humidifiers. The circulating air is humidified by hot seawater in the top and bottom humidifiers respectively, and then goes to the middle dehumidifier to condense via a freshwater absorption process. Its design scheme and operating principle are introduced and a mathematical model describing its internal energy and mass flow process is established. An experimental setup with compound parabolic concentrator areas of 6 m2 is developed, and a sequence of experiments is carried out. The results indicate that its freshwater productivity can reach 29.6 kg/h with a gained output ratio of 0.84 when the feed seawater temperature is 80 ℃. Due to its compact structure, the freshwater production per volume unit per day reaches up to 224.1 kg/(day⋅m3). This work may promote the development of solar humidification and dehumidification systems towards low cost and high efficiency.

Combining high power laser modules with compound parabolic concentrators to test components at high heat fluxes

Assessing the performance and lifetime of components is a key step towards deploying new technologies in the aerospace and fusion sectors. Experimental testing at representative thermal conditions is particularly important when investigating novel materials that have yet to be fully characterized. This paper presents the key features of a new high-power laser facility developed to test components destined for extreme environments.This facility, OLAHF (Oxford LAser Heating Facility), provides a maximum power of 24 kW over an area of 200 mm by 104 mm for a base intensity of 1.15 MW/m2 via a combination of laser modules. A bespoke control system manages the laser and instrumentation systems as well as supporting cooling air and water infrastructure. A numerical model of the lasers is validated against supplier data, enabling high fidelity computational representation of experimental setups.Compound parabolic concentrators (CPCs) are investigated to increase applied laser power over smaller testing surfaces. A laser module-CPC system assessed the performance of gold and aluminum coatings at a range of surfaces roughnesses. High transmission efficiencies were demonstrated when surfaces are gold coated and below 0.1μm average roughness. Future plans for OLAHF are additionally presented, including additional test campaigns using higher power CPC systems.

Optical performance investigation for spatially separated non-imaging concentrator with congruent plane concentrating surface

The thermal deformation on the concentrating surface of traditional CPC (Compound Parabolic Concentrator, CPC) is effectively addressed by SCSA-CPC (Separation of Concentrating Surface and Absorber CPC, SCSA-CPC). However, the energy flux density distribution on the absorber of SCSA-CPC is uneven and the concentrating surface is still a curved paraboloid structure, which hinders practical engineering applications and lacks significant economic benefits. In the present research, five kinds of SS-CPCs (Spatially Separated CPC, SS-CPC) with different numbers of congruent plane concentrating surfaces, namely SS-CPC2, SS-CPC3, SS-CPC4, SS-CPC5 and SS-CPC6 were constructed based on non-imaging optics principles. The optical performances of the SS-CPCs were investigated and compared to SCSA-CPC with the same specification. It is found that SS-CPC allows for an increased acceptance angle of up to 41° while effectively improving the uniformity of energy flux density distribution on the absorber. The results also showed that the annual beam radiation collection time can be extended by 43.11 % and SS-CPC has a particular advantage in collecting diffuse radiation, indicating its high adaptability to weather changes. Moreover, due to the congruent planar structure of the concentrating surface, SS-CPC holds promising prospects for practical engineering applications.