The concentrated photovoltaic/thermal system (CPVT) adopting spectral beam splitting is a promising field of solar energy research. However, the thermo-electric properties of fluid-based CPVT collectors, which depend strongly on the non-uniform concentrated energy flux, remain unclear. This study aims to fill the gap and explore the thermo-electric properties of fluid-based CPVT collectors under non-uniform energy flux based on the finite volume method (FVM) with the Monte Carlo Ray-Trace (MCRT) method. The actual solar flux distribution on the receiver surface is obtained using Tracepro software. Then, the realistic non-uniform energy flux was employed in ANSYS Workbench 2022R1 software as a boundary condition to increase the accuracy of the CFD modeling of the system. The model is validated by comparing the results of the reference data. Moreover, the impact of uniform and non-uniform energy flux on the PV cell temperature is analyzed. In addition, the effects of mass flow rate on the electrical and thermal performance of the system are investigated. The results show that the PVT hybrid system has high conversion efficiency, with a total efficiency of more than 50%. Notably, the extreme non-uniformity of the solar-concentrated energy flux can result in local overheating of the PV cell, which may lead to irreversible damage.

Renewable energy represented by solar energy has played an important role in the transformation of the energy consumption structure of the world. This study describes and studies a hybrid photovoltaic/thermal (HPVT) system using a linear Fresnel reflector concentrator (LFRC) and nano-fluid spectrum filter (NFSF). The method of designing the HPVT system is provided. Ag/water and Ag-CoSO₄/water NFSFs used for this HPVT system were prepared and experimentally tested. Optical analysing results indicate that the optical efficiencies of the PV cell module (PVCM) and NFSF are 0.7556 and 0.9053 under the condition of 0.3° solar tracking error (STE), demonstrating good adaptable capacity to the STE. Moreover, the operating performances of the HPVT system using different NFSFs are compared. The comparison results demonstrate that compared with the Ag/water NFSF, the introduction of CoSO₄ can enhance the thermal performance but decrease the photovoltaic efficiency of the HPVT system. When the Ag-CoSO₄/water (1.2 mg–3 g/130 mL) NFSF is used, the photovoltaic and thermal efficiencies of the whole HPVT system are 0.1366 and 0.4259, and the overall exergy efficiency is 0.209. The exergy efficiency of the HPVT system will be improved if the NFSF temperature is increased appropriately or if the external convection heat transfer coefficient and environment temperature are reduced.

The central shaft is an important and indispensable part of a small scale urban vertical axis wind turbines (VAWTs). Normally, it is often operated at the same angular velocity as the wind turbine. The shedding vortices released by the rotating shaft have a negative effect on the blades passing the wake of the wind shaft. The objective of this study is to explore the influence of the wake of rotating shaft on the performance of the VAWT under different operational and physical parameters. The results show that when the ratio of the shaft diameter to the wind turbine diameter (α) is 9%, the power loss of the wind turbine in one revolution increases from 0% to 25% relative to that of no-shaft wind turbine (this is a numerical experiment for which the shaft of the VAWT is removed in order to study the interactions between the shaft and blade). When the downstream blades pass through the wake of the shaft, the pressure gradient of the suction side and pressure side is changed, and an adverse effect is also exerted on the lift generation in the blades. In addition, α = 5% is a critical value for the rotating shaft wind turbine (the lift-drag ratio trend of the shaft changes differently). In order to figure out the impacts of four factors; namely, tip speed ratios (TSRs), α, turbulence intensity (TI), and the relative surface roughness value (k_s/d_s) on the performance of a VAWT system, the Taguchi method is employed in this study. The influence strength order of these factors is featured by TSRs > k_s/d_s > α > TI. Furthermore, within the range we have analyzed in this study, the optimal power coefficient (C_p) occurred under the condition of TSR = 4, α = 5%, k_s/d_s = 1 × 10⁻², and TI = 8%.

This study aims to elucidate the mechanisms by which tip seal leakage flow induces steam excitation, thereby enhancing the operational safety of steam turbines. Using numerical simulations, it investigates the detailed characteristics of the flow field in the turbine tip seal cavity. By introducing Boundary Vorticity Flux (BVF) into the tip seal flow field, this research explores the relationship between leakage vortex structures in non-uniform flow fields at the blade tip and the resulting steam excitation forces. The results demonstrate that, during eccentric rotor operation, the extent and intensity of vortices within the seal cavity vary, lead to changes in the BVF distribution along the shroud surface, which in turn alter the tangential forces and induce variations in lateral excitation force at the blade tip. Additionally, the non-uniform flow in the tip seal clearance induces circumferential pressure variations across the shroud, leading to adjustments in radial excitation force at the blade tip.

Jiang, T.; Du, L.; Zhang, L., and Cao, L., 2018. Effect of circulating water temperature change on the dynamic characteristics of ocean ship thermal-system heater. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 81–85. Coconut Creek (Florida), ISSN 0749-0208. In this paper, the sections of superheating, condensate and sub-cooling of drain water in a ocean ship thermal-system heater are set as a unit. The heat storage capacity of the heater itself is considered and the sudden change of the circulating water temperature was set as turbulence. A mathematical model was conducted to calculate the outlet temperature of circulating water, the flow rate of extraction steam and the saturation temperature in the ocean ship thermal-system heater. And the changed trends of these parameters are analyzed under the turbulence. Then the dynamic process of heater from the state with turbulence to a new stable state was obtained. Finally, the balancing speed of the other parameters of ocean ship thermal-system heater was analyzed according to the time that the dynamic process took to reach a new stable state.

Mining, mineral processing, and power generation are just a few of the industries that have made extensive use of pneumatic conveying systems in recent years. The market for pneumatic conveying is anticipated to grow to a value of $30 billion by 2025. However, problems with the pneumatic conveying process are common and include coal particle damage, pipe wall wear, and excessive system energy consumption. A new systematic framework for decision-making is created by combining the Theory of Inventive Problem Solving (TRIZ) with the Decision-Making Trial and Evaluation Laboratory (DEMATEL). This methodology employs TRIZ-Ishikawa to determine the underlying causes of issues from six different perspectives. It then suggests remedies based on TRIZ technical contradictions and uses DEMATEL to examine how the solutions interact to determine the best course of action. This study confirms the viability of this approach in recognizing fundamental contradictions, producing workable solutions, and reaching scientific conclusions in challenging issues by using instances such as wear and tear, obstructions, and low conveying efficiency in pneumatic conveying system elbows. It offers particular references for real engineering projects and suggests practical solutions like employing quick-release flanges and installing multiple sets of airflow regulators.