Receiver Geometry Research Articles

Optical and Thermal Modeling of a Cylindrical– Hemispherical Receiver

Receiver geometry optimization is a crucial domain in enhancing the efficiency of parabolic dish concentrators. This optimization necessitates thoroughly scrutinizing the receiver's optical and thermal characteristics. The present study engages in a cylindrical-hemispherical receiver's optical and thermal modeling. Set at an aperture of 0.150m, the receiver's height varies between 0.150m to 0.160m. Sol-Trace software is employed for the optical modeling to analyse the total amount of heat flux absorbed by the receiver that has been concentrated using parabolic dish. The diameter of the is taken as 3m, and the receivers placement is varied between 1.55m and 2.05m from the dish concentrator to obtain the optimal distance for absorbing maximum heat flux. From the results optimal distance has been observed as 1.8m from the dish concentrator. Maximum heat flux of 6664.56W has been absorbed by the receiver surface at this position. Additionally, thermal modeling using CFD has been conducted to calculate convective heat losses from the receiver under different wind conditions, such as varying wind direction and wind velocity. The maximum convective heat loss observed under head-on wind conditions is 772.73W, while under back-on wind conditions, it is 606.84W

A comprehensive review on integration of receiver geometries, nanofluids, and efficient thermal energy storage for solar parabolic dish collectors

A comprehensive review on integration of receiver geometries, nanofluids, and efficient thermal energy storage for solar parabolic dish collectors

Impact of different receiver geometries on a reconfigurable intelligent surface assisted multi-cell VLC system in the presence of light path blockage.

We report the effect of integrating metasurface-aided reconfigurable intelligent surfaces (RISs) on the signal-to-interference-plus-noise ratio (SINR) and data rate of a multi-cell visible light communication (VLC) system. RIS has been deployed in the channel between transmitter and receiver to redirect the reflected light in the desired directions, even in the absence of line-of-sight (LoS) links. Results show that the introduction of RIS has improved average SINR but reduced average illumination level compared to a no-RIS system. As the quantity of RIS increases, a discernible improvement in the maximum SINR value is observed. Here, three different receiver geometries, namely, a photodiode (PD), freeform diversity receiver (FDR), and modified FDR (MFDR), have been adopted. The impact of individual receivers has been reported in the presence of light path blockage. MFDR geometry is found to be most suitable with more coverage probability compared to the other two receivers. With (40c m×24c m) RIS area, during blockage, MFDR maintains an average SINR of 21.95dB, which is 97.29% and 14.24% greater than PD and FDR, respectively.

Energy density source levels of underwater explosive charges

This paper presents experimental measurements of energy density source levels of small explosive charges for high frequencies to 18 kHz. The experiments were carried out using Signals Underwater Sound (SUS) charges deployed at a deep water site in a coastal fiord north of Vancouver BC. The waveform of an underwater explosion is characterized by a high intensity shock wave signal followed by a series of bubble pulses of decreasing intensity. The bubble pulses dominate the SUS energy density spectrum at frequencies below 1 kHz, but at higher frequencies the spectrum is dominated by the characteristics of the decay envelope of the shock wave signal. The explosive material in SUS charges is packed in a thin cylindrical cavity, resulting in a non-uniform decay envelope with secondary pulses when detonated, and a non-spherical distribution of the radiated sound. The impact of the cylindrical charge shape on energy density source level was investigated experimentally. Data were recorded for SUS deployments that generated in-line and broadside sound propagation to the receiver with respect to the axis of the cylindrical charge. Experimental measurements indicate significant differences in the high frequency SUS energy density spectrum depending upon the SUS and receiver geometry.

Target-oriented acquisition geometry design based on full-wavefield migration

The ultimate goal of survey design is to find the acquisition parameters that enable acquiring high-quality data suitable for optimal imaging, while fulfilling budget, health, safety, and environmental constraints. We develop a target-oriented acquisition design algorithm based on full-wavefield migration. The algorithm optimizes a receiver density function that indicates the number of receivers per unit area required for obtaining the best possible image quality. The method makes use of available seismic data to create a reference model that is included in our objective function. To make the design target oriented, the objective function is multiplied with a mask that gives more weight to the target areas of interest. The results of the 2D and 3D implementations indicate an optimized receiver density function with higher values at the zones where more data are needed for improving image quality. The corresponding receiver geometries have more receivers placed in these areas. We validate the results by computing the images of the target zone using uniform and optimized geometries. The use of the latter indicates an improvement in the image quality at the target zone. In addition, we compute the number of receivers required for achieving a certain signal-to-noise ratio after imaging based on the optimized receiver density function.

Numerical investigation to optimize the modified cavity receiver for enhancement of thermal performance of solar parabolic dish collector system

The concentrated parabolic dish collector (PDC) systems are widely utilized for the purpose of generating high-temperature heat by receiving and converting solar energy efficiently into thermal energy. Cavity receivers including spiral coils have a common use in PDC system for optimal thermal performance. Therefore, to enhance the thermal performance of a PDC system, the present study investigates different cavity receiver configurations, such as cylinder and conical shaped receivers with flat and spherical absorber surface as well as the effect of spiral coil arrangement. To identify the most optimal spirally coiled cavity receiver, the comparison is conducted based on outlet temperature, heat exchange rate, thermal efficiency, effectiveness, and thermal performance capability (TPC). The investigations were conducted using the ANSYS Fluent CFD simulation software package. The SolTrace software package was utilized to compute the maximum heat flux incident on the absorber surface of the receiver, and peak heat flux data was used as input parameter at the absorber surface of the receiver. Furthermore, to select the suitable working fluid in PDC system, different heat transfer fluids, such as Syltherm 800, Xceltherm 600, ParathermHR™ and water, respectively were studied. From the thermal analysis of various proposed receiver geometries, the receiver with conical shape and spherical absorber surface is more efficient over other configurations. It provides 50 % higher heat transfer rate thancylindrical receiver with flat absorber surface. Moreover, receiver's thermal performance could modestly be improved by modifying the spiral coil pitch (variable pitch). In terms of pumping power consumption, readily availability, low viscosity, and high specific heat, water is suggested as working fluid for receiver of PDC system.

Optical and thermal investigation of hyperbolic cavity receiver with secondary reflector for solar parabolic dish collector

A hyperbolic-shaped cavity-type receiver with a second stage reflection for a 40 m2 solar parabolic dish concentrator (PDC) is presented in this paper,along with optical and thermal modeling. The receiver geometry and the secondary reflector complete the hyperbolic geometrical shape of the present receiver. This study aims to estimate heat losses owing to natural convection and radiation under influential parameters associated with solar parabolic dish system. Optical modeling has been performed with verified model using ASAP® 2013 V1R1. The optical simulations have been carried out for varying receiver height (h1), height of the secondary (h2) and diameter-to-total height ratios (d/h) of 0.5, 1, and 1.5 while keeping the diameter of the plane aperture of the receiver (d) constant. The optimum receiver geometry has been selected based on the performance in terms of optical efficiency. The maximum efficiency found is 91.72% for h1 = 0.75 m and d/h = 0.5 for the mounting distance of 4.21 m. The optimized shape is further studied to determine how the receiver absorptivity and the secondary reflector's reflectivity affect the optical performance. The absorptivity and reflectivity range from 0.86 to 0.94. Obtained optimum receiver geometry from the optical investigation is further analyzed to estimate the heat transfer rate. The thermal modeling is performed for 0°, 30°, 60°, and 90° orientations of the receiver in ANSYS Fluent 2020 R1. A comprehensive comparison among the available models has been reported and validated with well-established experimental data. This work has developed free convective Nusselt number correlation. It can be a valuable addition to the existing literature.

Investigation of the Influence of Inner Geometries of the Receiver Tube of a Parabolic Trough Collector System Used for Water Heating

Solar collectors are devices that help to harvest solar thermal radiation and convert into other forms of energy. Because of its low fabrication cost and simple design, the Parabolic Trough Collector (PTC) is one of the finest alternatives for medium-temperature (i.e., in 80°𝐶𝐶-250°𝐶𝐶 range) needs among all types of concentrated solar collectors. The absorber tube or the receiver tube is one of the main critical components of a PTC. Thermal radiation of the sun falling onto a parabolic reflector is reflected to its focal line where the receiver tube is placed. Therefore, the performance of a PTC system significantly depends on Receiver Geometries (RGs). A locally developed PTC system with a new and accurate tracking system was designed and fabricated in the current study and steam generation inside the receiver was considered in the performance analysis. The experimental analysis was performed using seven different RGs. The experiments were carried out by measuring generated steam every 10 minutes for all the RGs, and simultaneously, solar insolation data was taken by a domestic solar Photovoltaic (PV) system with a capacity of 5 kW. The steam generation data was taken only when the power output of the reference solar PV system was ≥ 4kW. Having tested seven different RGs, the researchers were able to improve the steam generation to a maximum of 10.0% compared to the reference geometry using direct experimental data. This was 8.1% in accordance with the statistical approach via multiple linear regression model. A three-dimensional mathematical model for two-phase flow was formulated for a closed domain. Restricting this model into twodimensional geometry, the steam generation process was simulated as a TPF problem using ANSYS Fluent software. The volume fraction profiles clearly show the phase transition, which leads to evaporation and condensation inside the tube.

Construction of pseudo-Hessian for vertical seismic profile full waveform inversion

The pseudo-Hessian matrix has been widely developed and applied to full waveform inversion to reduce the computational cost of obtaining the Hessian and its inverse matrix. Because the conventional pseudo-Hessian matrix assumes a surface seismic profiling geometry, this conventional method is compatible only with horizontally deployed sources and receiver geometries and cannot reflect the geometrical spreading effect of vertically deployed receivers. To enable the pseudo-Hessian to properly consider vertically deployed receiver locations and the geometrical spreading inherent in vertical seismic profiling data, we re-formulate part of the pseudo-Hessian matrix formulation. We verify our new scheme by directly calculating the Hessian matrices for a simple 1D model and conducting inversion tests with synthetic data sets. A comparison to the approximated Hessian matrix confirms that the vertical seismic profiling pseudo-Hessian provides better agreement with the approximated Hessian than the conventional pseudo-Hessian. In addition, we describe two numerical tests using multi-offset synthetic vertical seismic profiling data sets. When we apply the conventional pseudo-Hessian matrix to invert the synthetic data, we find that the inversion process cannot properly invert far offset data. However, we find that the pseudo-Hessian regarding vertical seismic profiling geometry allows the inversion process to invert far offset data and produces fewer artifacts than the conventional method. This study demonstrates that the vertical seismic profiling pseudo-Hessian matrix represents an alternative method that is necessary for the calculation of the pseudo-Hessian matrix for full waveform inversion with vertical seismic profiling using the Gauss–Newton method.

Modeling a solar pressurized volumetric receiver integrated in a parabolic dish: Off-design heat transfers, temperatures, and efficiencies

Concentrated solar power plants are commonly recognized as one of the most attractive options within carbon-free power generation technologies because of their high efficiency and feasible hybridization and/or storage implementation. In this work, a complete heat transfer analysis for an air volumetric receiver coupled to a parabolic dish focused on distributed generation (in the range of kWe) is carried out. It includes most relevant heat losses. Dish collector optical efficiency is computed by means of a ray-tracing software while the thermal performance of the solar receiver is modeled under steady-state conditions using a comprehensive set of equations with a clear physical origin and meaning. Detailed information on the temperatures and heat transfers along the different inner and outer receiver zones are computed with a built from scratch in-house code programmed in Mathematica®. The model considers the main losses from convection, conduction and radiation and through the surrounding insulator. The resulting thermal efficiency mainly depends on the incoming solar irradiance at the glass window, the receiver geometry and the type of materials considered, as well as on the ambient temperature. Explicit numerical results are given at two locations under different meteorological conditions. Optical efficiencies reach values of about 84%. For irradiance values around 800–900 W/m2, at the receiver outlet, air can reach temperatures of about 1200K and receiver thermal efficiency is over 80%. It is expected that this model (precise but not too expensive from the computational viewpoint) could help to identify the main efficiency bottlenecks, paving the way for optimization when designing this type of concentrated solar plants through further coupling with a power block, as Brayton or other cycles.

An information theoretic Bayesian uncertainty analysis of AEM systems over Menindee Lake, Australia

SUMMARY Long-range, active-source airborne electromagnetic (AEM) systems for near-surface conductivity imaging fall into two categories: helicopter (rotary-wing) borne or fixed-wing aircraft borne. A multitude of factors such as flying height, transmitter loop area and current, source waveforms, aerodynamic stability and data stacking times contribute to the geological resolvability of the subsurface. A comprehensive comparison of the relative merits of each system considering all such factors is difficult, but test flights over well-constrained subsurface geology with downhole induction logs are extremely useful for resolution studies. However, given the non-linear nature of the electromagnetic inverse problem, handling transmitter–receiver geometries in fixed-wing aircraft is especially challenging. As a consequence of this non-linearity, inspecting the closeness of downhole conductivities to deterministic inversion results is not sufficient for studying resolvability. A more comprehensive picture is provided by examining the variation in probability mass of the depth-wise Bayesian posterior conductivity distributions for each kind of AEM system within an information theoretic framework. For this purpose, probabilistic inversions of data must be carried out. Each acquiring system should fly over the same geology, survey noise levels must be measured and the same prior probabilities on conductivity must be used. With both synthetic models as well as real data from over the Menindee calibration range in New South Wales, Australia, we shed new light on the matter of AEM inverse model uncertainty. We do this using two information theoretic attributes derived from different Kullback–Leibler divergences—Bayesian information gain, and a strictly proper scoring rule, to assess posterior probabilities estimated by a novel Bayesian inversion scheme. The inversion marginalizes fixed-wing geometry attributes as generic nuisance parameters during Markov chain sampling. This is the first time-domain AEM study we know of, that compares nuisance marginalized subsurface posterior conductivities from a fixed-wing system, with rotary-wing derived posterior conductivities. We also compare field results with induction log data where available. Finally, we estimate the information gain in each case via a covariate shift adaptation technique that has not been used before in geophysical work. Our findings have useful implications in AEM system selection, as well as in the design of better deterministic AEM inversion algorithms.

Evaluating imaging uncertainty associated with the near surface and added value of vertical arrays using Bayesian seismic refraction tomography

AbstractTraditional tomographic methods do not consider the uncertainties associated with near-surface velocities and static corrections and provide a deterministic solution to the estimation problem. However, these uncertainties significantly affect structural mapping and interpretation of seismic imaging results. On the other hand, Bayesian first-arrival tomography provides multiple near-surface models that fit observed traveltimes equally well and enable the study of potential solution distributions. We demonstrate this approach on a complex synthetic near-surface model, representative of arid environments, to quantify associated velocity and statics uncertainties. We evaluate two different parameterizations for subsurface velocities in the context of near-surface Bayesian tomography: Voronoi tessellation with natural neighbor interpolation and the more conventional Delaunay triangulation with linear interpolation. Our analysis shows that the Voronoi cell parameterization with natural neighbor interpolation is more appropriate for this problem. Finally, the new approach is applied to compare two alternative acquisition geometries comprising conventional surface receivers and surface receivers augmented with vertical receiver arrays. The results demonstrate that adding vertical receiver arrays to conventional surface receivers can significantly reduce the near-surface velocity uncertainty and thus increases the accuracy of the seismic imaging results. Furthermore, the study shows that Bayesian tomography can be used as a tool for evaluating different source and receiver geometries during the acquisition design stage.

Optimizing Semi-Airborne Electromagnetic Survey Design for Mineral Exploration

As semi-airborne mineral exploration has a limited budget, it is critical to design experimental procedures that generate data to maximize desired information. We investigated the effects of transmitter–receiver geometries for a variety of anomalies and semi-airborne layouts. Our simulations indicated that flight line spacing of 200 m and a point distance of 100 m provides the optimal trade-off between coverage and survey progress for various targets. Based on the target size and distance between the transmitter and the target, the transmitter length should be at least equal to the length of the target. However, where the distance between the transmitter and the target is more than 1 km, the transmitter length should be at least two or three times the target size. Of similar importance are the location and direction of the transmitter cables, which can have a significant impact on the result of inversion and should be parallel to the target strike. By using more than one transmitter, better results can be obtained. If the strike of the target is known, transmitters should be parallel to each other, and if not, it is better to use perpendicular transmitters. The results of this study showed that the optimal distance between transmitters is 3 km. Our simulations showed that it is even possible to recover targets just below the transmitter in corresponding areas of masked data.

Instantaneous GNSS Ambiguity Resolution and Attitude Determination via Riemannian Manifold Optimization

We consider the problem of Global Navigation Satellite System (GNSS)-based attitude determination. A GNSS attitude model with nonlinear orthonormality constraints is used to rigorously incorporate the a-priori knowledge of the receiver geometry. Given the characteristics of the employed nonlinear constraints, we formulate GNSS attitude determination as an optimization problem on a Riemannian manifold. We design a Riemannian algorithm to deliver the constrained float attitude matrix solution. Subsequently, the constrained float solution, combined with a proposed decomposition of the objective function, is utilized to enhance the efficiency of the integer ambiguity search. Both simulation and experimental evidences demonstrate the superiority of the proposed method. The results reveal that the proposed method can maintain the high probability of resolving the integer ambiguities correctly while enjoying the low computational complexity compared with the state-of-the-art techniques.

Experimental investigation of improved parabolic trough solar collector thermal efficiency using novel receiver geometry design

Experimental investigation of improved parabolic trough solar collector thermal efficiency using novel receiver geometry design

Seismic acquisition design based on full-wavefield migration

The ultimate goal in survey design is to obtain the acquisition parameters that enable acquiring the most affordable data that fulfill certain image quality requirements. A method that allows optimization of the receiver geometry for a fixed source distribution is proposed. The former is parameterized with a receiver density function that determines the number of receivers per unit area. We optimize this receiver density function through an iterative gradient descent scheme that minimizes the difference between the image obtained with the current acquisition geometry and a reference image. The reference image is obtained from prior subsurface information that is assumed to be available. We tested the method with different subsurface models. The results indicate that the acquisition geometry is optimized according to the complexity of each subsurface model. The receivers are moved toward the areas where more data are needed for obtaining better imaging.

Optimization of corrugated-receiver solar collector's geometry using LBM analysis based on curved boundary scheme

BackgroundDue to growing demand of renewable energy for reducing the air pollution and costs, the optimization of the thermal systems using the renewable energy are attractive for the researchers. At this end, a parabolic trough solar collector, which converts the solar radiation to consumable heat energy for the daily use, is studied by numerical approach. This solar collector is consisted by a reflector gathering the solar radiation, corrugated solar receiver and inner tubes. MethodsThe lattice Boltzmann method (LBM) is utilized to solve the governing equations, and the curved boundary approach is taken into account to treat with the curved boundaries. With this combination, the accuracy and reliability of the results may be guaranteed. Using Koo-Kleinstreuer-Li (KKL) correlations, the Al2O3-water nanofluid's thermal/physical parameters, such as thermal conductivity and dynamic viscosity, are predicted before being inserted into the collector. Significant FindingsRayleigh number (103<Ra<106), nanoparticle concentration (0<φ<0.04), and receiver geometry were all examined variables. In addition, the main goal of the present work is to find an optimized geometry for the receiver of a solar collector. The hydrothermal efficiency and the second law analysis are the basis of the optimization.

Boiling sodium and melting salt: Evaluation and optimisation of a novel solar–thermal system concept

The phase-change phenomenon facilitates efficient heat transfer and the storage of a large amount of heat close to an upper-bound temperature limit. In this paper, a novel solar-thermal system configuration is evaluated and optimised, where liquid sodium is boiled in a receiver and energy is stored through the melting and freezing of NaCl salt. Polar and surround field configurations of a 1 MWe sodium-boiler plant were investigated where co-optimisation of solar multiple, field parameters, receiver geometry and storage parameters was performed to obtain lowest possible levelised cost of electricity (LCOE); this compared to a 100 MWe two-tank molten salt plant optimised via the same method. The LCOE values obtained for the 1 MWe sodium-boiler plant was 128.3 USD/MWh for a polar field configuration and 144.9 USD/MWh for a surround field configuration, compared to 107.1 USD/MWh for the 100 MWe two-tank molten salt system. Whilst promising for smaller-scale systems, the analysis identifies limitations and challenges associated with high operating temperatures and low receiver flux limits, which opens the possibilities for the investigation of lower-temperature phase change materials (PCMs) and alternative PCM geometries. • Phase change thermal energy storage is coupled with a boiling sodium solar receiver. • A detailed physical model is used to optimise the design for lowest energy cost. • The system achieves 128 USD/MWhe at 1 MWe scale with 14 h of storage.

Gradient-based optimization of micro-scale pressurized volumetric receiver geometry and flow rate

This study focuses on the design optimization of a micro-scale pressurized volumetric receiver by changing geometry and flow rate constrained by the volume, outlet air temperature, and outer surface temperature. The pressurized volumetric receiver model is replicated from an existing model, which assumes constant air pressure and neglects the convection loss from the cavity. The existing model is revised from a solver to a design optimizer.The replicated model is restructured using OpenMDAO (Open-source MultiDisciplinary Analysis and Optimization) framework, and analytical derivatives are implemented for efficient derivative calculation to increase optimization performance. The replicated model is verified, and the maximum outlet air temperature difference is less than 0.05%. Optimization performance, selection of optimizers, the effect of the domain size, and radiative methods are discussed. The combined impact of the design variables is observed by selecting SLSQP (Sequential Least SQuares Programming) and trust-region optimizers. Optimization performance is tested in different domain sizes and compared with a design of experiments analysis. For testing the impact of radiative heat transfer methods to design optimization, the Rosseland approximation, and P1 method are selected. Depending on the design domain, a solution methodology is suggested for future receiver design optimizations applicable for macro-scale pressurized volumetric receivers.

Natural Ground Information Detection Method Based on GNSS Ground Reflection Delay Signal

For natural surface disasters in key areas, if small deformations such as surface subsidence and displacement can be continuously monitored, it can provide early warning and effectively protect people's lives. In the past, small deformations were mainly measured by using GNSS direct signal to calculate displacement changes or by using SAR information, which can only measure one point. To monitor the deformation of an area, multiple monitoring points need to be deployed. Based on this, this paper mainly adopts GNSS ground reflection delay signal, and according to the different information of direct and reflection signal paths, combined with the geometry of receiver and ground reflection point and satellite, it can solve the small deformation of the ground surface, and realize the original point measurement to surface measurement while maintaining the original measurement accuracy, so as to improve the high-precision monitoring range and reduce the number of monitoring points.