查看更多>>摘要：Solar photovoltaic (PV) building integration is a key means of achieving the goal of zero-carbon buildings. Differences in morphology parameters of urban block lead to significant variations in PV power generation potentials (PVGP). Therefore, this paper aims to develop a five-levels PVGP assessment methodology, including radiation potential (RP), installation potential (IP), technical potential (TP), economic potential (EP) and carbon reduction potential (CRP), and quantify the comprehensive impact of morphology indicators on the PVGP of office blocks, using Wuhan as an example. Firstly, this paper proposed an innovative five-levels PVGP assessment method based on Rhino&Grasshopper platform; Then, architectural typology approach was adopted to classify the morphological typologies of real office block samples; Afterwards, the comprehensive impact of morphological indicators on PVGP was quantified; Finally, solar energy utilisation strategies applicable to office block renovation and new construction scenarios were proposed. The findings indicated that multi-storey slab office blocks had the best TP, EP and CRP, with 47.11 kWh/m2/y, 14.28 years, 0.218 RMB/kWh, and 482.22 kg CO2/ m2, respectively. The building roofs area to fa & ccedil;ades ratio and building shape factor were the key morphological parameter combinations affecting TP and CRP. The building roofs area to fa & ccedil;ades ratio, envelope to site area ratio, building length to depth ratio and sky view factor were the key morphological parameter combinations affecting the economic payback period and PV power generation cost. The PVGP assessment model constructed in this paper can be extended globally, and the findings provide a design baseline for for the integration of PV modules and buildings suitable for office blocks renewal and solar planning in new blocks to build carbon- -neutral blocks.
查看更多>>摘要：Analytical models are commonly used for simulating radiative flux density distributions (RFDD) on the receiver in the design, optimization and operation of solar power tower systems. However, existing analytical model simulation methods typically accumulate the simulation results of individual heliostats sequentially, leading to inefficiencies, high computational costs and loss of the efficiency advantage of the analytical model, especially for large-scale heliostat fields. In this paper, a novel real-time and accurate RFDD simulation method for large-scale fields based on an analytical model is proposed, namely fast-NEG (Neural Elliptical Gaussian). The proposed simulation method re-frames the slow sequential accumulation process into highly parallelized computation on a graphics processing unit (GPU), where each thread computes the radiative flux density mapping from a receiver pixel to a visible heliostat. The efficient parallel simulation process is applicable to all Gaussian or elliptical Gaussian analytical models. The accurate NEG model is adopted and accelerated by tensor product decomposition and precomputation to describe the RFDD of the individual heliostat. The FastNEG simulation is compared with the state-of-the-art method Quasi-Monte Carlo Ray Tracing (QMCRT) on a large-scale field with 6282 heliostats at different times of one year, resulting in simulation speed improvement by two orders of magnitude, and a mean relative error of total energy, peak value and Root Mean Square Error (RMSE) are 0.40%, 0.25% and 0.0068%, respectively. Compared with the prevalent analytical model simulations, the Fast-NEG approach significantly enhances the simulation accuracy and boosts the efficiency by 1-7 orders of magnitude.
Hossain, SalmanArika, All MumtahinaFahim, Iffat NowshinUddin, Jamal...
1.1-1.16页
查看更多>>摘要：The efficiency of photovoltaic (PV) modules significantly reduces due to accumulation of dust. To minimize the dust effect on PV in a cost-effective manner, optimal cleaning interval need to be decided. To accomplish this objective, machine learning(ML) models can be utilized to detect dust level on PV beyond predefined threshold which would then aid in deciding whether or not to clean the panels without on-site human intervention. With this goal, this study analyzes the detrimental impact of dust on PV systems in Bangladesh and proposes a novel ML classification based dust detection method followed by development of a cleaning system. Several ML classifiers have been implemented and their performance are evaluated, with the best performing model Artificial Neural Network (ANN) achieving the highest accuracy of 98.11%. Upon dust detection by the ML model, the water sprinkler cleaning system gets wirelessly activated by the user, which effectively removes dust by spraying pressurized water onto the panel. The proposed cleaning system restores dusty PV module efficiency to match to that of the clean module (14.87%). Moreover, an economic study has been done by quantifying the decrease inefficiency as a financial loss to assess the viability of the cleaning system. The result shows that the proposed cleaning system is economically viable for PV systems having capacities above 2.89 kWp.
查看更多>>摘要：For high-pressure applications, like direct steam generation or hydrothermal liquefaction, homogenizing the radiative flux on the tubular receiver of the parabolic trough concentrators can help avoid thermal stresses and potential material degradation. In the present study Monte Carlo ray tracing is used to analyze different secondary mirrors to enhance the flux uniformity level over the receiver tube of four parabolic troughs with different rim angles. Elliptical, V-shaped, Lambda-shaped (inverted V), and Compound Elliptical Concentrator (CEC) mirrors are considered. The design of these mirrors is optimized for each case using a Differential Evolution Algorithm. Solutions are sought with the maximum possible uniformity while keeping high optical efficiency. Results of the optical modeling show reductions in peak flux over the tube wall by approximately 60% when secondary mirrors are implemented with PTC systems. Furthermore, optical efficiencies of 90% and flux uniformity levels of 86.6% can be achieved by integrating the Elliptical and Lambda-shaped geometries as secondary mirrors. The effect of the secondary mirrors on the PTC efficiency for off-normal incidence was also studied. CECs are very good at increasing off-normal rays' acceptance, followed by V-shaped mirrors, but at the cost of a worsened overall performance.
查看更多>>摘要：This study explores the effect of an external magnetic field on the performance of a PV/T spectral splitting system employing Fe3O4@SiO2 nanofluid. The distribution characteristics of magnetic nanoparticles were manipulated to modify their optical properties and thermal conductivity. As a result, the photothermal and photovoltaic conversion efficiencies, along with the merit function (MF value) of the PV/T system, were enhanced. First, the experiment tested different magnetic pole orientations. Results demonstrated that the solar energy utilization rate was highest under the S-S pole orientation. Second, the influence of the magnetic field height ratio on system performance was investigated. The results indicated that changes in the height ratio altered the direction of the magnetic force on nanoparticles. The system achieved optimal performance at a height ratio of 0.5, with thermal and electrical efficiencies of 73.5% and 11.9%, respectively. Third, the study of different magnetic field width ratios revealed that at a width ratio of 1.5, the system's thermal efficiency reached 75.2%, and the electrical efficiency was 12.0%, with the highest MF of 2.12, significantly outperforming the system under no magnetic field. Magnetic recovery experiments assessed the recyclability of Fe3O4@SiO2 nanofluid. Under a magnetic field strength of 150 mT, a recovery rate of 92.3% was achieved. These findings offer valuable insights for applying magnetic nanofluids in PV/T spectral splitting systems.
查看更多>>摘要：In the quest for more efficient solar thermal systems, accurately determining the thermal emittance of low- emissive materials is crucial in determining the power losses. This paper describes the calorimetric method designed to precisely measure the thermal emittance of Selective Solar Absorbers (SSAs) to be used in High Vacuum Flat Plate Collectors (HVFPCs). The method's capability is demonstrated through the successful correction of thermal emittance values for copper samples of varying sizes, including dimensions down to 49 cm2. Results highlight the method's potential to significantly reduce measurement errors associated with small- size and/or low-emittance samples, providing a path forward to improve the design and efficiency of SSAs. This research marks a significant step in advancing solar thermal technology by enabling emittance measurements with a precision better than 0.003, which is essential for the development of high-performance solar thermal absorbers. The method has also been applied to correct the thermal emittance value of SSA measured in previous measurement campaigns, and it allows a better estimation of the SSA efficiency conversion curve.
查看更多>>摘要：The agricultural industry is a vital sector in many countries, significantly contributing to employment through both direct and indirect links with food processing and distribution. This research is a sustainable and ecofriendly solution, to conserve two apricot varieties, Carmen and Aurora, in Morocco's agri-food industry. Utilizing an indirect convective solar dryer under various aero-thermal conditions, the study demonstrates a notable decrease in moisture content for Carmen and Aurora apricots, from initial values of 86.38 % and 82.75 % respectively, to 26.78 +/- 3 % (wet.basis). By examining the drying kinetics of apricot slices, the research establishes diffusion coefficients ranging from 4.65 10-10 to 24.40 10-10 m2/s for Carmen and from 3.24 10-10 to 14.16 10-10 m2/s for Aurora, with the coefficients varying as temperature increases. The Arrhenius equation, indicating an activation energy of 5434.87 kJ/kg, effectively describes the temperature dependency of the diffusion coefficient. Notably, the conductive drying kinetics of apricot slices were found to be best described by the Midilli-Kucuk model. The overall energy consumption exhibited a downward trend as temperatures increased and an upward trend with higher airflow rates. Additionally, the findings showed that higher air temperatures led to better energy efficiency. To assess the performance of the solar dryer being studied, an exergy analysis was conducted. The exergy efficiency of the convective dryer varied between 22.24 % and 54.12 % for Aurora, and between 31.6 % and 57.32 % for Carmen. This innovative approach highlights the potential of green energy in enhancing agricultural practices and product preservation.
查看更多>>摘要：Japan's commitment to achieving net-zero emissions by 2050 includes a target for solar photovoltaic (PV) to generate 14%-16% of the nation's electricity by 2030, as outlined in the Sixth Strategic Energy Plan. To support the potential contributions of ordinary citizens, this research analyzes the factors influencing the deployment of residential and small-scale solar PV systems in Japanese municipalities, providing local government units with data-driven insights to formulate strategies for expanding solar energy. A Random Forest Regression model assesses each factor's impact on municipal solar PV capacity share. SHAP values highlight feature importance and visualize the most influential independent variables. Results indicate that local energy demand is the primary driver of solar PV installations. For residential systems, economic factors such as taxable income serve as secondary drivers, while high land values impede growth. In the case of small-scale installations, land availability becomes a critical limiting factor, particularly in regions with limited land, even when energy demand remains high. The study demonstrates that proactive local governments can overcome economic and land-use challenges through targeted subsidies, strategic partnerships, innovative use of public spaces, and strict enforcement of land-use regulations. By highlighting the significance of local energy demand and citizen involvement, this study offers valuable insights for policymakers to prioritize areas with lower energy demand and implement targeted supportive policies, thereby fostering amore balanced distribution of solar PV installations. Japan's case may serve as a reference for optimizing solar PV deployment strategies globally, contributing to the broader discourse on small-scale renewable energy expansion.
查看更多>>摘要：We report on the design, commissioning, validation, and operation of a highly adjustable, fully automatic miniaturized multi-row high-alpine photovoltaic array, installed at an altitude of around 2'500 m. asl. in Davos, Switzerland. The 1:12-scaled field consists of three rows of seven back-to-back monofacial panels each (virtually bifacial), capable of independently and quickly varying row spacing, module angle, and ground slope angle within considerable boundaries. This allows to simultaneously record the real-world performance of a wide range of plant configurations at decently short intervals. A co-located full-size static PV installation featuring mono- and bifacial modules at differing inclinations is used to validate the measurement accuracy. The results are compared to state-of-the-art yield estimate simulations using the commercial software PVsyst. During the first experimental campaign in the winter half-year 2023/24, we observed higher than expected real-world yields (by 7 to 16%), likely caused by an underestimation of the Albedo in snow-covered surrounding.
NETL
NSTL
Elsevier