Off-design Operating Conditions Research Articles

Development and assessment of a low-emissions gas turbine system for power utilities incorporating intercooling and solar preheating

• 1. Two novel solar-hybrid gas turbines with high compression ratios are proposed. • 2. The novel cycles use PTCs to preheat the compressed air before their combustors. • 3. A high solar share of 24.3% and lower CO2 emissions of 28.14 can be achieved. • 4. The novel cycles have high efficiencies and low electricity costs. • 5. The novel cycles have low fuel consumption rates with short payback periods. Literature shows that using medium-temperature solar collectors, such as parabolic trough collectors (PTCs), to heat the gas turbine's compressed air before it enters the combustion chamber is unfeasible with high-pressure ratio gas turbines. This is because the compressor's outlet air temperature exceeds the solar field's maximum operating temperature. In this study, PTCs technology was integrated into intercooled gas turbine cycles to solve this problem. Intercooling a gas turbine improves its performance and allows for solar energy integration of PTCs. Two inventive solar preheated intercooled gas turbine power plants with a high-pressure ratio of 37 have been proposed and investigated: solar preheated single-intercooled gas turbines (SP-IcGT single ) and solar preheated double-intercooled gas turbines (SP-IcGT double) . Under design and off-design operation conditions, the plants' performance and optimal solar field area were evaluated. A comprehensive economic and environmental analysis of the novel cycles was also conducted and reported. The study shows that the solar integration of PTCs with intercooled gas turbines is a promising technique, providing a fuel-based efficiency of 54% for the SP-IcGT double and 51.3% for the SP-IcGT single . In addition, the analysis shows that the novel cycles have a high solar share, save more fuel, and are more environmentally friendly than solar-preheated conventional gas turbines. SP-IcGT double saves 28.2% and SP-IcGT single saves 19.3%. The SP-IcGT double and SP-IcGT single consume 6675 and 7017 kJ/kWh, respectively, compared to 9500 kJ/kWh for solar preheated conventional gas turbines in the previous literature. Furthermore, the economic analysis shows positive prospects for solar preheated intercooled gas turbine projects. The SP-IcGT double has a payback period of 6.409 years and the SP-IcGT single has 5.545 years. Overall, the solar integration of PTCs with intercooled gas turbines is an attractive technology in Sunbelt countries.

Small-scale ORC-based unit for domestic micro-cogeneration operating in the temperature range of the solar thermal flat panels

CO2 emissions related to the energy demand in commercial and residential buildings account for over 15% of worldwide greenhouse gases emissions. This issue requires the development of new solutions, technologies, and energy management strategies to reduce the environmental impact of this sector. Simultaneous heat and power production, namely cogeneration, is a proven method for this purpose. Among the different power systems, Organic Rankine Cycle (ORC) plants allow the production of mechanical and electric energy using hot sources at low temperature levels. This feature allows to combine this technology with solar collectors, making it possible to exploit the thermal energy exceeding the thermal needs when the solar irradiation is high. In this paper, an experimental characterization of a Solar Organic Rankine Cycle (SORC) is presented. The hot source of the power plant is reproduced by water heated up to 120 °C by two 12 kW electric resistances and stored in a buffer tank with a capacity of 200 L. The 1 kW ORC unit is equipped with a scroll volumetric expander operating off-grid. The main control variable of the unit is the pump speed which is varied in each operating condition to guarantee a superheating degree at the expander inlet. Since the variability of the solar source is a critical issue in these applications, off-design operating conditions have been tested, showing the capability of the plant to be also operated far from the design point. The maximum efficiency of the unit reached 4.7 % while the highest net power was 400 W. A further test conducted to evaluate the transient performances of the unit demonstrated its small inertia and the capability of the expander to produce power right after the unit activation.

Control law synthetizing for an innovative indirect precooled airbreathing engine under off-design operation conditions

Indirect precooled engine (IPE) is a promising power for single-stage-to-orbit (SSTO) and the booster stage of a two-stage-to-orbit (TSTO) vehicles. Thrust of IPE is realized the most decisive factor that affects vehicle mission performance; therefore it is particularly critical to ensure that the engine can fully exert its thrust performance through active control since the flight parameters will change substantially alongside the trajectory. On account of this, control law of maximizing thrust for a single branch IPE is developed in current study. To this end, a high-fidelity off-design model of IPE is constructed to evaluate how engine performance is regulated by the various changeable parameters. The results indicate that engine thrust and specific impulse are functions of total fuel mass flow, nozzle throat area and the temperatures of preburner and main combustor, which can be conveniently controlled in real engines by actuators or changing the related fuel mass flow through fuel valves. Based on the influence characteristics revealed, the maximum thrust control law of the engine is synthetized, with the range of engine thrust can be regulated along a representative flying trajectory is evaluated. The results may provide some useful guidance about performance control of IPE with complex multi-branch intermediate cycles.

Numerical Investigation of Near-Tip Modifications for a Highly Loaded Low-Speed Rotor Under the Influence of Double Leakage

Abstract This paper numerically investigates the flow field in the tip region of a highly loaded axial low-speed compressor rotor. The rotor in focus is of a hybrid blade configuration, featuring a tandem profile in the mid-span region and single blade profiles near the endwalls. The simulated 1.5-stage configuration also consists of a single row inlet guide vane (IGV) and a tandem stator. Due to high loading coefficients (Ψ = 0.58) in combination with moderate flow coefficients (ϕ = 0.58), double leakage of the tip leakage vortex plays a major role at all operating conditions. As already shown in the past, double leakage is a stability influencing dominant flow phenomenon in compressor rotors and influencing that can be the key to an efficient working range enhancement on compressor stages. This work introduces a simple and powerful method of enhancing the working range for low-speed rotors under the influence of double leakage. It is shown, that modifications to the pressure side (ps) shape of rotor tip profiles can influence the interaction of the tip leakage vortex with the adjacent blade, comparable to the effects of casing treatments. These unconventional blade shapes result from the transformations from tandem blade configurations to hybrid blades near the endwalls. The resulting single blade profile close to the tip features a convex profile element (an increase in local thickness, called the “belly”), which significantly influences the local static pressure gradients. This unusual pressure-side profiling can change mass flow over the tip and, by correct positioning, may reduce the amount of double leakage and, consequently, increase the rotor’s efficient working range. This work presents the geometry definitions for the hybrid blade single-segments, a detailed analysis of the impact on design and off-design operating conditions together with their underlying flow phenomena, and finally proposes design guidelines for the blade-tip geometries of highly loaded rotors under the influence of double leakage.

Performance Analysis of Heat Exchangers and Integrated Supercritical CO2 Brayton Cycle for Varying Heat Carrier, Cooling and Working Fluid Flow Rates

Supercritical CO2 power systems offer the potential of reduced system footprint and improved thermal efficiency, through the development and adoption of compact heat exchangers. Among these heat exchangers, the microtube, printed circuit, and plate heat exchangers are emerging as the most promising technologies for heat addition to the cycle, heat recuperation and heat rejection, respectively. To investigate the performance of supercritical CO2 recuperated Brayton cycle for heat to power conversion, simulation models of the heater, recuperator and cooler were developed using the distributed modeling approach and the ε-NTU method and then integrated with turbomachinery models to form the cycle model. The influences of flow rates of the heat carrier, cooling and working fluids on the heat exchanger performance and the integrated system were investigated. For the studied power system and under the off-design operating conditions, the net thermal efficiency of the cycle varies between 14.1% and 16.8%. Results show that increasing in the working fluid flow rate remains the net power output of the cycle but decreases the net cycle thermal efficiency, while increasing in the heat carrier fluid increases both, and the increase of cooling fluid increases the net power output but maintains the net thermal efficiency.

Estimation of the Induced Incidence of a High Reaction Axial Turbine Bucket

This paper describes the effect of the incidence angle of the bucket on the performance of the axial turbine stage. The off-design operating conditions of the turbine stage result in a change in the velocity diagrams. This results in a positive or negative incidence. One of the basic objectives in turbine stage design is to estimate the flow behaviour of the turbine stage during off-design operation as accurately as possible and to quantify the corresponding decrease in efficiency. The available loss prediction models allow the estimation of the loss distribution when the incidence angle changes in the preliminary design phase. However, the incidence angle is actually affected by the velocity of circulation, which changes the input velocity vector (induced incidence). Thus, the blade row angle of attack is different from the angle based on the velocity diagram calculations. The result of our paper is a relation for estimating the angular difference of the input flow angle to the bucket defined as a function of the turbine operation mode.

Characterization of the Fluid Damping in Simplified Models of Pump-Turbines and High Head Francis Runners

In order to satisfy the power demand in the electrical grid, hydraulic turbine units frequently work under off-design operation conditions and pass through transient events. These operation conditions can lead to high vibration amplitudes in the turbine runners, decreasing their useful life, and in some cases to premature failures. To determine and to understand the behaviour of the fluid damping is a relevant topic, because this parameter limits the maximum amplitude in resonance conditions. The runner of some types of turbines, such as reversible pump-turbine and high head Francis turbine, can be modelled as a disk-like structure, due to their similar mode shapes. Because of this, in this work, the fluid damping of a vibrating disk was studied. The disk was submerged in water and was put in a resonant state at different vibration amplitudes. Moreover, this structure was excited at different distances to a rigid surface, in order to analyse the effects of the distance between the runner and the casing. The main effects on the fluid damping were determined and characterized, showing a dependency of the fluid damping ratio on the different parameters.

Sensitivity analysis of a swirling flow to the GEKO model

Accurate numerical models for hydraulic turbine applications are highly coveted. They must be able to correctly capture the swirling flow found at off-design operating conditions in the turbine draft tube. The GEKO model is a relatively fast and flexible eddy viscosity turbulence model with adjustable coefficients to tune the model to different flow scenarios. In this study, the GEKO model is tested on a swirling flow inside a diffusor similar to the flow conditions found at part-load operation of a propeller turbine. The diffusor investigated corresponds to the Porjus U9 draft tube cone section, including the runner cone. Results showed that the near-wall coefficient, with a value of 2, increased the wall shear stress and moved the separation point from the runner cone further downstream. Moreover, with a value of 0.7, the separation coefficient increased the eddy viscosity, which also moved the separation point from the runner cone further downstream. Both coefficients gave velocity profiles closer to experimental values and increased the swirl number at the outlet of the diffusor by up to 36.9 % compared to the GEKO default model. Overall, the near-wall coefficient with a value of 2 gave the best results. The GEKO model provides an opportunity to tweak numerical models to swirling flow.

Experimental study of the flow of the Tr-Francis turbine along the no-load curve

Emergence of new renewable energies, such as solar or wind power, has introduced intermittency on the grid. Hydraulic turbines, initially designed to perform close to their best efficiency point, are more and more at off-design operating conditions, such as no-load regimes, when the runner rotates without energy extraction. These no-load regimes are characterized by complex flow phenomena inducing fluctuations of the blade loading and resulting in a reduced lifetime of the runner. Understanding the origins of pressure fluctuations in no-load conditions is consequently essential to prevent fatigue damage to the turbine. This paper presents the study, with experimental flow visualization, pressure measurements and numerical simulations, of the flow behavior at speed no-load in a medium head Francis turbine model. Evolution of the different flow structures along the no-load curve is then assessed. At speed-no-load, flow visualizations show the presence of a cavitating zone at the blade trailing edge. According to the results of the numerical simulations, this zone seems to correspond to the region where a backflow in the draft tube enters the runner. This interaction results in a backflow inside the runner and in a blockage of the upper part of the inter-blade channel. Sensitivity of this cavitating region to test parameters (discharge and rotation speed) is investigated for different no-load operating points with high-speed visualization at a constant cavitation number. Decrease of the energy coefficient tends to intensify the phenomena and increase the volume of cavitation.

A novel and optimized operation strategy map for CCHP systems considering optimal thermal energy utilization

Load mismatch between consumer's demand and CCHP system's supply under frequent varying off-design operation conditions has been a lingering problem for the last twenty years. Existing operating maps for CCHP systems have failed to provide optimal operating strategies since they are simply derived based on the Following Thermal/Electricity Load methods. In addition, these maps only consider one performance curve of gas turbines, and these maps' boundaries are not rigorously derived. Severe energy waste issues may occur if the existing maps of CCHP systems are employed in practical applications. This study proposes a novel operating strategy map for CCHP systems, providing optimal load matching solutions with improved energy-saving performance. The typical operating methods of a gas turbine, for example, the reducing turbine inlet temperature method and the compressor inlet air throttling method, are also considered in the analysis. Accordingly, the derived map is divided into seven optimal operating areas. Each area has a specific optimal solution. In addition, a case study is conducted to validate the energy-saving performance of the proposed strategy under practical applications. Results have revealed that the primary energy saving ratio is markedly improved by 11.7% by employing the proposed novel strategy when compared with a hybrid method.

Convolutional Neural Network Identification of Stall Flow Patterns in Pump–Turbine Runners

Stall flow patterns occur frequently in pump turbines under off-design operating conditions. These flow patterns may cause intensive pressure pulsations, sudden increases in the hydraulic forces of the runner, or other adverse consequences, and are some of the most notable subjects in the study of pump turbines. Existing methods for identifying stall flow patterns are not, however, sufficiently objective and accurate. In this study, a convolutional neural network (CNN) is built to identify and analyze stall flow patterns. The CNN consists of input, convolutional, downsampling, fully connected, and output layers. The runner flow field data from a model pump–turbine are simulated with three-dimensional computational fluid dynamics and part of the classifiable data are used to train and test the CNN. The testing results show that the CNN can predict whether or not a blade channel is stalled with an accuracy of 100%. Finally, the CNN is used to predict the flow status of the unclassifiable part of the simulated data, and the correlation between the flow status and the relative flow rate in the runner blade channel is analyzed and discussed. The results show that the CNN is more reliable in identifying stall flow patterns than using the existing methods.

Performance Assessment of Low-Temperature A-CAES (Adiabatic Compressed Air Energy Storage) Plants

The widespread diffusion of renewable energy sources calls for the development of high-capacity energy storage systems as the A-CAES (Adiabatic Compressed Air Energy Storage) systems. In this framework, low temperature (100°C–200°C) A-CAES (LT-ACAES) systems can assume a key role, avoiding some critical issues connected to the operation of high temperature ones.In this paper, two different LT-ACAES configurations are proposed. The two configurations are characterized by the same turbomachines and compressed air storage section, while differ in the TES section and its integration with the turbomachinery. In particular, the first configuration includes two separated cycles: the working fluid (air) cycle and the heat transfer fluid (HTF) cycle. Several heat exchangers connect the two cycles allowing to recover thermal energy from the compressors and to heat the compressed air at the turbine inlet. Two different HTFs were considered: air (case A) and thermal oil (case B). The second configuration is composed of only one cycle, where the operating fluid and the HTF are the same (air) and the TES section is composed of three different packed-bed thermal storage tanks (case C). The tanks directly recover the heat from the compressors and heat the air at each turbine inlet, avoiding the use of heat exchangers.The LT-ACAES systems were modelled and simulated using the ASPEN-Plus and the MATLAB-Simulink environments. The main aim of this study was the detailed analysis of the reciprocal influence between the turbomachinery and the TES system; furthermore, the performance evaluation of each plant was carried out assuming both on-design and off-design operating conditions. Finally, the different configurations were compared through the main performance parameters, such as the round-trip efficiency.A total power output of around 10 MW was set, leading to a TES tank volume ranging between 500 and 700 m3. The second configuration with three TES systems appears to be the most promising in terms of round-trip efficiency since the energy produced during the discharging phase is greater. In particular, the round-trip efficiency of the LT-ACAES ranges between 0.566 (case A) to 0.674 (case C). Although the second configuration assures the highest performance, the effect of operating at very high pressures inside the tanks should be carefully evaluated in terms of overall costs.

마이크로 수력 발전을 위한 프로펠러형 림구동 축류 터빈 설계

A design method for a propeller type rim-driven axial-flow turbine for a micro-hydropower system is presented. The turbine consists of pre-stator, impeller and post-stator, where the pre-stator plays a role as a guide vane to provide circumferential velocity to the on-coming flow, and the impeller as a rotational power generator by absorbing angular momentum of the flow. BEM(Blade Element Method), which is based on the turbine Euler equation, is employed to design the pre-stator and impeller blades. NACA 66 thickness form and a=0.8 mean camber line, which is widely accepted as a marine propeller blade section, is used for the pre-stator and turbine blade section. A CFD method, derived from the discretization of the RANS equations, is applied for the analysis of the designed turbine system. The design conditions of the turbine is confirmed by the CFD calculation. Turbine characteristic curve is calculated by the CFD method, in order to provide the performance characteristics at off-design operation conditions. The proposed procedures for the design of a propeller type rim-driven axial-flow turbine are established and confirmed by the CFD analysis.

Design and operation of organic Rankine cycles for varied power load

ABSTRACT The organic Rankine cycles (ORC) always operate under off-design conditions due fluctuations in renewable energy access and actual user demand. Therefore, this study considered geothermal ORC as the research object to obtain the optimal design. The off-design performance was investigated under varied load curves by selecting different design loads. First, the optimal ORC system with a constant-rate load was obtained through minimizing the specific investment cost. For this optimal system, the exergy efficiency initially increased and then decreased under off-design operation conditions. Moreover, the peak efficiency was improved by increasing the design pressure. Second, the load curves of different users were considered, including industry, business, and residents. To achieve the best operational performance of the ORC for these varied load curves, different rate loads and pressures were selected, and then the off-design performance was studied. The results demonstrate that the rate load and maximum demand load are not optimal and that the optimal load ratio (rate load divided by the highest demand load) is 60%. The operating evaporation pressure obtained through the design is 1.9 MPa. For the optimal ORC, compared with a system with a load ratio of 1.0 (rate load is equal to the highest demand load), the total investment cost decreased by approximately 30.7%, and the average exergy efficiency increased by 19.2%.

Time series aggregation-based design and operation optimization of a solar-driven organic Rankine cycle incorporating variation of environmental temperature and solar radiation

The efficient utilization of renewable energy, e.g., solar energy, has become a major requirement to build a clean and efficient energy system and achieve the goal of carbon neutrality. Organic Rankine cycle (ORC) is one of the most promising technologies for converting solar energy into power. However, life-span low operation performance is still a barrier to the wide-spread application of ORC. Design and off-design operation optimization is significant in improving the life-span performance of ORC. In the routine methods, the ORC system is usually designed under a specific rated condition. However, the ORC mostly operates under off-design conditions. The conventional method separates the off-design operation process from the design process and typically loses solution optimality. In the present study, the off-design operation conditions are incorporated into the design process. A time series aggregation-based method for design and operation optimization of a solar driven ORC is proposed. K-means algorithm is applied to achieve the optimal aggregation operating points for the environmental temperature and solar radiation. The design and operation optimization model incorporating the off-design component performance is developed. The optimal design and operating schemes are achieved based on the aggregated operating points, and the effectiveness of the proposed method is validated. The results indicate that the ORC obtained by the proposed method features a 37.37% lower electricity production cost compared with the conventional method.

Computational Prediction of the Performance Map of a Transonic Axial Flow Compressor

Aviation fuel efficiency is an important target for aviation industry. Aircraft engine compression ratio is a key factor to improve fuel consumption. Compression ratio can be increased using transonic compressor. In this study, performance prediction of a transonic axial compressor at design and off-design operating conditions is investigated numerically using ANSYS-CFX software. The compressor is NASA Rotor 37. Firstly, the performance at design point is predicted, where mesh independence study is performed to determine suitable mesh size. Three-dimensional flow details for meridional plane, blade-to-blade plane and airfoil surface are explored. The design point study successfully captured flow features such as shock waves and flow separation regions. When compared with experimental data, the predicted compressor pressure ratio deviation error is less than 5%. 3D flow details show that shock wave strength increases from hub to tip. The shock wave moves backward as we move from hub to tip indicating that the flow separation covers lesser portion of the blade. Secondly, off-design performance is predicted for various rotational speeds. A simple procedure is utilized to predict surge and choke limits. The predicted compressor map is compared with experimental data and it shows overall root mean square error less than 5%. The success of the method developed in this research make it a viable method to be used in the design phase of transonic compressors to evaluate the effect of design modifications for both design and off-design operating conditions.

Off-design modeling of a microturbine combined heat & power system

There is increasing interest in decision support software tools that evaluate the techno-economic potential of distributed energy system technologies for deployment in combined heat and power (CHP) applications, such as commercial buildings, microgrids, and connected communities. This trend is particularly evident among end-users looking to integrate renewable resources with more traditional CHP technologies for on-site generation and enhanced resiliency. However, many of these software tools do not account for part-load and off-design characteristics of prime mover and heat recovery equipment, resulting in lower accuracy for both the optimal selection and sizing and the economic value proposition of integrated hybrid renewable energy-CHP systems. Microturbine technology is an attractive distributed energy resource whose performance is sensitive to both part-load and off-design (i.e., excursions of ambient conditions away from the design point temperature and pressure) operating conditions but is widely unreported. In the present work, we address this deficiency by developing a detailed, thermodynamic model of a commercial 200 kW microturbine CHP system and paramaterizing results for incorporation into the Renewable Energy Optimization (REopt) tool developed by the National Renewable Energy Laboratory. The details of the microturbine model, including model benchmarking and validation, are presented. Microturbine off-design modeling includes part-load analysis, assessment of ambient sensitivities, and mapping heat recovery heat exchanger response to hot water grade requirements. The model is then exercised in several illustrative examples to depict the numerous factors which alter electric power, electric efficiency, and hot water recovery. Model results show, for example, predictions of a 4 percentage point electric efficiency range occurring between intake air temperatures of -18 to 50 °C. Likewise, the model closely predicts the 25 % loss in heat recovery while at -18 °C and the 8 % gain in heat recovery while at 35 °C. An additional case shows how heat recovery may increase or decrease by 9.5 % of the design value when changing the return water temperature plus-or-minus 22 °C. In particular, the impact of ambient conditions on best-possible microturbine performance is conveyed through hourly simulations of the system subjected to the weather of different geographic locations within the United States. • A model of a 200 kW microturbine configured for hot water recovery is developed. • Part-load modeling approach and simulation results for both electric efficiency and waste heat recovery are detailed. • Off-design performance as functions of ambient temperature and pressure is explored. • Heat recovery performance maps as functions of return and supply hot water temperatures are developed.

Performance and Unsteady Pressure Pulsation Analysis for a Double Suction Centrifugal Pump at Off-Design Operating Conditions

Performance and Unsteady Pressure Pulsation Analysis for a Double Suction Centrifugal Pump at Off-Design Operating Conditions

Centralized power generation with carbon capture on decommissioned offshore petroleum platforms

The existing cogeneration systems on offshore petroleum platforms face clashing targets intrinsic to offshore applications, namely, weight, area, cost and efficiency. Moreover, the prolonged offdesign operating conditions during their lifetime further increase the inefficiencies, leading to increased environmental impact. Thus, in this work, centralized power stations are designed for supplying the electricity required by various identical floating production, storage and offloading units (FPSOs) in the offshore oil and gas sector. This approach aims to increase the performance and alleviate the environmental burden that the conventional utility systems are responsible for by integrating carbon abatement technologies. Since these modifications bring about an increase in the initial investment cost and the financial feasibility of the system, a techno-economic assessment and optimization process is necessary in order to determine the optimal configuration of the power hubs. To this end, a combined thermodynamic, environmental and economic analysis, together with space and weight allowance quantification is performed. The use of adapted and decommissioned FPSOs for installing the power hub is a novel proposal that reduces the initial investment cost. As a result, the advanced utility systems provide higher overall power generation efficiencies (above 10 percentage points) compared to existing simple cycle gas turbine systems, even at fourfold lower emissions. The incremental economic analysis has found that, for moderate carbon taxations (> 40 USD/tCO2), the advanced power generation systems may economically outperform the conventional offshore power plants. Lastly, a delay in entry of operation between FPSOs of up to 4 years may reduce the investment cost by 50%, while maintains the same thermodynamic performance.

Machine learning and CFD for mapping and optimization of CO2 ejectors

In this study, a novel simulation-based algorithm for CO2 ejector design and performance evaluation is presented. The algorithm is based on an automated Computational Fluid Dynamics (CFD) workflow that can account for different ejector geometries and operating conditions. The CFD data points are used to train a Gaussian Process Regression (GPR) machine learning model to predict the ejector performance indicators; efficiency, mass flow rates, outflow uniformity, and entropy generation. Three use cases are investigated using this methodology: 1) performance mapping for off-design operating conditions of a given ejector, 2) design mapping of ejector performance with 5 geometry variables investigated, and 3) flow structure prediction between different ejector mixing chamber geometries. The results show that this algorithm can be used to efficiently explore ejector designs with mean average errors between 0.07 and 0.1 [–] in entrainment ratio. Furthermore, the method can to look for optimized geometries using gradient descent methods, as well as produce ejector performance maps. Additionally, the method is able to predict local flow structures of velocity and pressure inside the ejector with varied ejector geometries. The databases and GPR method implementation from this work is made available open-source for further development and research.