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Solar−coal hybrid power generation (SCHPG) system is one of the interesting solutions for solar power generation. This research aims to find a more viable integration mechanism of solar energy into a coal‐fired thermal power plant in terms of techno‐economic and ecology perspective. Performance of the 300 MW SCHPG system in the nominal and part‐load condition is analyzed under three different integration mechanisms. Numerical simulation of 300 MW SCHPG system is investigated under four different cases using a thermal balance approach. Operation modes of fuel‐saving (FS) and power‐boosting (PB) are considered for each case. Among the proposed cases, Case 4 is obtained as a good operation performance, which is recommended as the main case. The solar energy in Case 4 is used for evaporating feedwater and steam superheating, and steam reheating. Results show that the optimal aperture area of the heliostat solar field is 330 330 m2, and the minimum levelized cost of electricity is 0.1847 USD kWh−1. In Case 4, thermal efficiency is increased by 7.19% with standard coal consumption reduced by 45.3 g kWh−1 compared to a reference power plant. In the SCHPG system, coal consumption is reduced by 26.8 tons h−1 in FS mode, whereas power output is increased 30 MW h−1 in PB mode. [ABSTRACT FROM AUTHOR]

Temperature and thermal stress analyses of receiver can provide theoretical guidance to the suppressing of thermal stress. Coupled-field element method is adopted to conduct temperature and thermal stress field analyses of tube receiver under non-uniform and intermittent concentrated solar irradiation. During the temperature analyses of tube receiver, angle relationships between incident direction of solar rays and surface elements of tube receiver are calculated, and the relationships multiplied by magnitude of concentrated solar irradiation are used as the secondary boundary condition of temperature analyses. The secondary derivative of temperature field along length direction of tube receiver is also investigated to clarify the thermal stress distribution along length direction. The numerical results indicate that axial stress and tangential stress have much higher influence on thermal stress field than radial stress, and the inflexion of secondary derivative of temperature distribution will induce an inflexion of thermal stress distribution. [ABSTRACT FROM AUTHOR]

Abstract: With the aim to increase incoming solar intensity and decrease focus spot radius, a new type of solar surface cladding reactor with concentration quartz window is put forward in this paper. The comparisons of dimensionless heat flux distribution on working surface between the solar surface cladding reactor with concentration quartz window and the cladding reactor with plane quartz window are investigated by Monte Carlo ray tracing method. Besides, the impacts of refractivity and characteristic parameter of concentration quartz window on focus spot radius and peak solar intensity are also studied. [Copyright &y& Elsevier]

Abstract: The distribution of concentrated solar irradiation has a significantly impact on the temperature distribution of porous media receiver. The thermal performance of porous media receiver is investigated by combining the Monte Carlo Ray Tracing (MCRT) method and FLUENT software with user defined functions (UDFs). The MCRT method is used to obtain the heat flux distribution on the fluid inlet surface of porous media receiver. The calculated heat flux distribution is treated as the wall heat flux boundary condition of thermal performance analysis. The local non-equilibrium thermal equation (LNTE) model with Rosseland approximation is used to investigate the temperature distributions. Typical influences of the heat flux boundary condition, radiation heat loss, porosity, emissivity, flow mass and average particle diameter on the temperature distributions are investigated. [Copyright &y& Elsevier]

Accurately forecasting solar radiation is of great significance to solar energy utilization. To forecast the spatial and temporal distributions of solar radiation simultaneously, a deep neural network model named MRE-UNet is proposed, the solar radiation data in Heilongjiang province is taken as an example to test the forecasting performance in different periods ahead forecasting cases. According to the evaluation results, an 16 h historical solar radiation data was determined to be the best choice for input, and the minimum of MSE can reach 6.47 × 10−4, 1.38 × 10−3 and 2.69 × 10−3 for 1 h, 3 h and 6 h ahead forecasting cases, respectively. The transferability of the MRE-UNet is tested by performing the solar radiation nowcasting in Hubei province, China using the pre-trained MRE-UNet trained by the solar radiation data in Heilongjiang province. The robustness of MRE-UNet is tested by monitoring the effects of adding different level of noise, and MSE keeps to be 6.27 × 10−4 even though the measuring noise increase to be 50%. For further demonstration on the effectiveness of MRE-UNet in spatiotemporal forecasting, the performance in total cloud cover forecasting is also tested, and satisfactory forecasting results are obtained. Finally, spatiotemporal correlation analysis on solar radiation and total cloud cover data is carried out, a potential reason for satisfying forecasting performance of MRE-UNet is given. From this work, MRE-UNet proposed can be provided as an efficient tool for dealing with further solar radiation spatiotemporal forecasting problem, and the spatiotemporal correlation characteristics can be employed as the basis for further developing effective solar radiation forecasting approach to a degree. • The novel MRE-UNet model is proposed for solar radiation spatiotemporal forecasting. • The MRE-UNet proposed is characterized to be of very high transferability and robustness. • The MRE-UNet is demonstrated to be of high accuracies in total cloud cover forecasting. • Spatiotemporal correlation analysis is used to illustrate on the reason for satisfactory performance. [ABSTRACT FROM AUTHOR]

Abstract: The bottom surface of conventional cavity receiver cannot be fully covered by coiled metal tube during fabrication, which would induce a dead space of solar energy absorption. The dead space of solar energy absorption can severely decrease the optical efficiency of cavity receiver. Two new types of cavity receiver with bottom surface convex are put forward with the objective to solve the problem of dead space of solar energy absorption and improve the optical efficiency of cavity receiver. The optical efficiency and heat flux distribution of the two new types of cavity receiver are analyzed by Monte Carlo ray tracing method. Besides, the optical efficiency comparisons between conventional cavity receiver and the two new types of cavity receiver are conducted at different characteristic parameter conditions. [Copyright &y& Elsevier]

The hybridization of solar energy with a coal-fired power plant is a promising way to reduce the numerous environmental issues related to a coal-based power generation sector. This paper examines a novel integration mechanism of solar energy into a 300 MW coal-fired power plant to improve the performance and techno-economic feasibility of the proposed system while decreasing pollutant emissions by coal consumption reduction. The concept of a novel integration mechanism includes replacing a part of the steam being used in the steam turbine of the proposed system with steam produced using the solar field installed near the power plant. The performance and techno-economic analysis of a 300 MW solar coal hybrid power generation (SCHPG) system were investigated under four different reference days (i.e. 22nd of March, 22nd of June, 22nd of September, and 22nd of December). Although the results revealed that the SCHPG system can operate well over the year, it exhibited the highest performance and techno-economic feasibility for the 22nd of June due to the higher direct normal irradiance and small incidence angle. In contrast, the lowest performance and techno-economic feasibility occurred on the 22nd of December. Besides, the performance and techno-economic feasibility for the 22nd of March and 22nd of September are almost similar. • New integration mechanism of solar energy into a coal-fired power plant is proposed. • Power load and DNI are significant effects on techno-economic performance of SCHPG system. • Fuel-saving mode can significantly contribute to pollutant emission reduction. • Part-load conditions can be reduced more coal and CO 2 emission than nominal load. [ABSTRACT FROM AUTHOR]

Spectral beam splitting (SBS) hybrid PV/T system was a promising path for utilizing the full spectrum solar energy to cogenerate electricity and high-grade heat, with high conversion efficiency. To settle the balance between photoelectric and photothermal conversion performance for full spectrum solar energy utilization, the sunlight based on wavelength matching was divided into two or more parts at band-gap wavelength by a spectral beam splitter: sunlight with wavelength at and close to the band-gap of PV cell was directed to generate electricity, while the sunlight with rest wavelength was used for thermal output. SBS hybrid PV/T system can not only increase the overall efficiency, but can also decouple the photoelectric and photothermal conversion process in separated operation temperatures. The current state-of the-art review on the advancements of SBS hybrid PV/T system performed with the aid of nanofluids, nano-film and semitransparent PV cells was presented in this work, with emphasis on the latest developments during the last decade. Mechanisms of different SBS techniques, progress in system, thermodynamic and cost analyses of nanofluids, nano-film and semitransparent PV cell based SBS hybrid PV/T system were discussed in detail to give a comprehensive understanding of the nature of the full spectrum solar energy utilization and the factors impacting on the system efficiency. Though the cost increase can be offset by extra energy efficiency gain, the wavelength matching, optical losses and stability of SBS hybrid PV/T system needs to be solved for future industrial application. • Advancements of spectral beam splitting PV/T system was reviewed comprehensively. • Mechanisms of spectral beam splitting techniques was reviewed comprehensively. • Progress in system, thermodynamic and cost analyses were discussed in detail. • Problems of system needs to be solved for future application were discussed. [ABSTRACT FROM AUTHOR]

• SAPG system exhibited higher operating performance with many ecological advantages. • Higher techno-economic indices can be obtained when the high potential steam extraction system is replaced by solar energy. • SAPG system is strongly affected by the variation of DNI compared to the power output. • The off-design regime can be reduced more fuel and CO 2 emission compared to the design regime. • SAPG system can significantly contribute to environmental pollution reduction. Integrating solar energy into conventional thermal power plant is one of the most efficient approaches of solar energy utilization for power generation purposes with minimum pollutants in near and midterm. In this paper, we have investigated the integration of solar energy with 300 MW coal-fired thermal power plant by replacing the first high-pressure heater (HPH#1) with parabolic trough collector type solar field. Our study aims to analyze the performance of 300 MW solar-assisted power generation (SAPG) system at different operation conditions in terms of techno-economic and ecological indices. The SAPG system is investigated for both fuel-saving (FS) and power-boosting (PB) operation modes. We have observed the reduction of 0.19 kg/kWh and 391 kJ/kWh in specific steam consumption and specific heat consumption, respectively in SAPG system. Moreover, the specific equivalent fuel consumption is decreased by 14.92 g/kWh. In SAPG system with FS mode, coal consumption is reduced by 8.82 tons per hour compared to the base case whereas, for PB mode, power output is increased by 20 MW per hour compared to the base case. The possibility of an annual reduction of coal and CO 2 emission is calculated as 32,150 tons and 47,030 tons respectively when SAPG system operates at nominal load. Considering the annual amount of reduced coal and pollutant emissions in the total system, SAPG system can significantly contribute to the reduction of pollutant emissions. Furthermore, the economic analysis estimates that the simple payback period and the LCOE are approximately 5.91 years and 0.13 USD/kWh respectively in design condition. [ABSTRACT FROM AUTHOR]