Due to the dust deposition on the surface of photovoltaic modules and the air pollution, the power generation performance of photovoltaic modules will be significantly affected. In order to quantitatively estimate the effect of air quality and dust deposition on the power generation performance of photovoltaic modules, a distributed photovoltaic system on a building roof in Shanghai is studied in this paper. Both artificial and natural dust deposition conditions are tested in terms of the influence of these factors on the power generation efficiency of photovoltaic modules. The variation of solar radiation intensity with PM2.5 concentration in Shanghai and the variation of photovoltaic module power generation capacity with PM2.5 concentration are tested and analyzed. The experimental results show that the surface dust of photovoltaic module reduces the power and efficiency of photovoltaic module. Experimental comparison between the dusty photovoltaic module and clean photovoltaic module shows that the dust on photovoltaic modules can reduce the power and efficiency significantly, where the highest power generation decrease is 35.226% and the highest power generation efficiency decrease is 5.546% as indicated in the experiments. Result shows that the amount of solar radiation is exponentially correlated to the PM2.5 concentration. Practical application: The influence of air quality and dust deposition on the performance of distributed PV modules is of vital importance under severe particulate pollution in Shanghai. This research helps predict the degradation of the photovoltaic system power generation efficiency, and determine whether to clean up the dust on the photovoltaic system according to accumulated PM concentration. This reduces the cost of cleaning of the dust on photovoltaic system. This study provides theoretical and experimental basis for the design of the building roof mounted solar photovoltaic system according to the local haze condition.

In Northwest China, the concentration of sediment in the Yellow River is high. The flow patterns in the forebay and inlet tank of a pumping station on the river are disordered, and sediment deposition endangers the normal operation and safety of the pumping station. To address this problem, the three-dimensional two-phase water–sediment flow in the forebay of the pumping station is modeled using fluid simulation software, and diagrams of the sediment content and velocity streamline in the flow layers of different sections are obtained. Combined with the multiphase flow theory of mixtures and the realizable $k–\epsilon$ turbulent kinetic energy equation, the location and formation mechanism of each vortex, as well as the area and degree of sediment deposition in the forebay, are analyzed. The actual engineering and numerical simulation results are compared to verify the accuracy of the simulation, and the operating conditions of each pump port under different unit operating conditions are proposed. The results show that the deposition of sediment has different effects on the outlets of the pumps, but its impact on pump Nos. 4, 5, and 6 is small. After desilting, the velocity uniformity and deflection angle of pumps 4, 5, and 6 are improved to a certain extent. This study provides specific guidance for the construction and reconstruction of a pumping station forebay to avoid the impacts of backflow areas and sediment deposition to a certain extent.