The primary issues in the Himalayan Rivers are sediment and cavitation degradation of the hydroelectric power turbine components. During the monsoon season, heavy material is transported by streams in hilly areas like the Himalayas through regular rainfalls, glacial and sub-glacial hydrological activity, and other factors. The severe erosion of hydraulic turbines caused by silt abrasion in these areas requires hydropower facilities to be regularly shut down for maintenance, affecting the plant's overall efficiency. This article provides an in-depth examination of the challenges that can lead to cavitation, silt erosion, and a decrease in the efficiency of various hydroelectric turbines, and it demands attention on the design, manufacture, operation, and maintenance of the turbines. This study's main objective is to critically evaluate earlier theoretical, experimental, and numerical evaluation-based studies (on cavitation and silt erosion) that are provided and addressed throughout the study. As a part of this study, various strategies for mitigating the effects of these problems and elongating the time that turbine may be utilized before they must be replaced have been provided.

This review paper serves as a critical study on various techniques used to cool photovoltaic thermal (PV/T) systems and to improve their efficiency. The growing concern about generating clean energy has led people to develop PV/T systems, which can produce electricity and thermal energy simultaneously. The paper discusses the latest cooling arrangements employed in PV/T systems, including air cooling, water cooling, bi-fluid cooling, heat pipe cooling, and phase change material-assisted cooling. The study also discusses thermal, electrical, and exergy analyses, as well as maintenance optimization methods reported in previous publications, to better understand the benefits and constraints of various PV/T technologies. Additionally, a brief introduction to recent trends, such as artificial intelligence (AI)-based optimization of PV/T cooling systems, is provided. Several research gaps have been identified, including the long-term stability of nanofluids, the optimization of hybrid cooling technology, thermal management, exergy performance, maintenance, and AI-assisted aspects of the technology. Instead of presenting an innovative cooling technique, the current study aims to conduct an extensive literature review and comparative analysis on PV/T cooling technology.